ID: 15733083
Title: Zinc accumulation after target loss: an early event in retrograde degeneration of thalamic neurons.
Abstract: Accumulation of cytoplasmic zinc is linked with a cascade of events leading to neuronal death. In many in vivo models of zinc-induced cell death, toxic concentrations of synaptically released zinc enter vulnerable neurons via neurotransmitter- or voltage-gated ion channels. In vitro studies demonstrate, in addition, that zinc can be liberated from intracellular stores following oxidative stress and contribute to cell death processes, including apoptosis. Here we describe accumulation of intracellular zinc in an in vivo model of cell death in the absence of presynaptic zinc release. We focused on the lateral geniculate nucleus (LGN) because LGN neurons undergo apoptosis when separated from their target, the primary visual cortex (V1), and the LGN is mostly devoid of zinc-containing presynaptic terminals. Infant and adult rats and adult mice received unilateral ablation of V1, either by aspiration or kainate injection. One to 14 days later, brain sections were stained with selenium autometallography or fluorescently labeled to localize zinc, or stained immunochemically for activated caspase-3. V1 lesions led to zinc accumulation in LGN neurons in infant and adult subjects. Zinc-containing neurons were evident 1-3 days after aspiration lesions, depending on age, but not until 14 days after kainate injection. Zinc accumulation was followed rapidly by immunostaining for activated caspase-3. Our data indicate that like neurotrauma and excitotoxicity, target deprivation leads to accumulation of zinc in apoptotic neurons. Moreover, zinc accumulation in vivo can occur in the absence of presynaptic zinc release. Together these findings suggest that accumulation of intracellular zinc is a ubiquitous component of the cell death cascade in neurons.

ID: 25284286
Title: Zinc transporters ZnT3 and ZnT6 are downregulated in the spinal cords of patients with sporadic amyotrophic lateral sclerosis.
Abstract: The loss of homeostasis of essential metals is associated with various diseases, including neurodegenerative diseases. Previous studies have shown that the levels of zinc (Zn) are significantly higher in the cerebrospinal fluid of patients with amyotrophic lateral sclerosis (ALS). Zn transporters and metallothioneins tightly control intracellular and extracellular Zn levels. This study investigated the protein levels of ZnT, a Zn transporter family, in ALS patients and model mice. The mRNA expression of ZnT1, -3, -4, -5, -6, -7, and -10 was assessed in the spinal cords of human control subjects. ZnT3 and ZnT6 protein levels were significantly diminished in the spinal cords of sporadic ALS patients compared with controls. Furthermore, immunohistochemical staining demonstrated decreased ZnT3 and ZnT6 immunoreactivity in the ventral horn of the spinal cords in ALS patients. Moreover, immunohistochemical analysis revealed that all ZnTs expressed in the spinal cords were localized in a distinct subset of motor neurons. In addition, ZnT3 and ZnT6 protein levels were not altered in SOD1 (G93A) mutant transgenic mice before or after the onset of ALS symptoms compared with controls. These results suggest that ZnT3 and ZnT6 protein levels are decreased in the spinal cords of sporadic ALS patients; however, this did not occur merely via loss of motor neurons.

ID: 25659970
Title: Zinc: indications in brain disorders.
Abstract: Zinc is the authoritative metal which is present in our body, and reactive zinc metal is crucial for neuronal signaling and is largely distributed within presynaptic vesicles. Zinc also plays an important role in synaptic function. At cellular level, zinc is a modulator of synaptic activity and neuronal plasticity in both development and adulthood. Different importers and transporters are involved in zinc homeostasis. ZnT-3 is a main transporter involved in zinc homeostasis in the brain. It has been found that alterations in brain zinc status have been implicated in a wide range of neurological disorders including impaired brain development and many neurodegenerative disorders such as Alzheimer's disease, and mood disorders including depression, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and prion disease. Furthermore, zinc has also been implicated in neuronal damage associated with traumatic brain injury, stroke, and seizure. Understanding the mechanisms that control brain zinc homeostasis is thus critical to the development of preventive and treatment strategies for these and other neurological disorders.

ID: 25917047
Title: A truncating SOD1 mutation, p.Gly141X, is associated with clinical and pathologic heterogeneity, including frontotemporal lobar degeneration.
Abstract: Amyotrophic lateral sclerosis (ALS) is a degenerative disorder affecting upper and lower motor neurons, but it is increasingly recognized to affect other systems, with cognitive impairment resembling frontotemporal dementia (FTD) in some patients. We report clinical and pathologic findings of a family with ALS due to a truncating mutation, p.Gly141X, in copper/zinc superoxide dismutase (SOD1). The proband presented clinically with FTD and later showed progressive motor neuron disease, while all other family members had early-onset and rapidly progressive ALS without significant cognitive deficits. Pathologic examination of both the proband and her daughter revealed degeneration of corticospinal tracts and motor neurons in brain and spinal cord compatible with ALS. On the other hand, the proband also had neocortical and limbic system degeneration with pleomorphic neuronal cytoplasmic inclusions. Extramotor pathology in her daughter was relatively restricted to the hypothalamus and extrapyramidal system, but not the neocortex. The inclusions in the proband and her daughter were immunoreactive for SOD1, but negative for TAR DNA-binding protein of 43 kDa (TDP-43). In the proband, a number of the neocortical inclusions were immunopositive for α-internexin, initially suggesting a diagnosis of atypical FTLD, but there was no evidence of fused in sarcoma (FUS) immunoreactivity, which is often detected in atypical FTLD. Analogous to atypical FTLD, neuronal inclusions had variable co-localization of SOD1 and α-internexin. The current classification of FTLD is based on the major constituent protein: FTLD-tau, FTLD-TDP-43, and FTLD-FUS. The proband in this family indicates that SOD1, while rare, can also be the substrate of FTLD, in addition to the more common presentation of ALS. The explanation for clinical and pathologic heterogeneity of SOD1 mutations, including the p.Gly141X mutation, remains unresolved.

ID: 28049831
Title: Mobile zinc increases rapidly in the retina after optic nerve injury and regulates ganglion cell survival and optic nerve regeneration.
Abstract: Retinal ganglion cells (RGCs), the projection neurons of the eye, cannot regenerate their axons once the optic nerve has been injured and soon begin to die. Whereas RGC death and regenerative failure are widely viewed as being cell-autonomous or influenced by various types of glia, we report here that the dysregulation of mobile zinc (Zn2+) in retinal interneurons is a primary factor. Within an hour after the optic nerve is injured, Zn2+ increases several-fold in retinal amacrine cell processes and continues to rise over the first day, then transfers slowly to RGCs via vesicular release. Zn2+ accumulation in amacrine cell processes involves the Zn2+ transporter protein ZnT-3, and deletion of slc30a3, the gene encoding ZnT-3, promotes RGC survival and axon regeneration. Intravitreal injection of Zn2+ chelators enables many RGCs to survive for months after nerve injury and regenerate axons, and enhances the prosurvival and regenerative effects of deleting the gene for phosphatase and tensin homolog (pten). Importantly, the therapeutic window for Zn2+ chelation extends for several days after nerve injury. These results show that retinal Zn2+ dysregulation is a major factor limiting the survival and regenerative capacity of injured RGCs, and point to Zn2+ chelation as a strategy to promote long-term RGC protection and enhance axon regeneration.

ID: 28754988
Title: Zinc binding to RNA recognition motif of TDP-43 induces the formation of amyloid-like aggregates.
Abstract: Aggregation of TDP-43 (transactive response DNA binding protein 43 kDa) is a hallmark of certain forms of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Moreover, intracellular TDP-43-positive inclusions are often found in other neurodegenerative diseases. Recently it was shown that zinc ions can provoke the aggregation of endogenous TDP-43 in cells, allowing to assume a direct interaction of TDP-43 with zinc ions. In this work, we investigated zinc binding to the 102-269 TDP-43 fragment, which comprise the two RNA recognition motifs. Using isothermal titration calorimetry, mass spectrometry, and differential scanning fluorimetry, we showed that zinc binds to this TDP-43 domain with a dissociation constant in the micromolar range and modifies its tertiary structure leading to a decrease of its thermostability. Moreover, the study by dynamic light scattering and negative stain electron microscopy demonstrated that zinc ions induce auto-association process of this TDP-43 fragment into rope-like structures. These structures are thioflavin-T-positive allowing to hypothesize the direct implication of zinc ions in pathological aggregation of TDP-43.

ID: 29299811
Title: Impaired Cu-Zn Superoxide Dismutase (SOD1) and Calcineurin (Cn) Interaction in ALS: A Presumed Consequence for TDP-43 and Zinc Aggregation in Tg SOD1G93A Rodent Spinal Cord Tissue.
Abstract: Impaired interactions between Calcineurin (Cn) and (Cu/Zn) superoxide dismutase (SOD1) are suspected to be responsible for the formation of hyperphosphorylated protein aggregation in amyotrophic lateral sclerosis (ALS). Serine (Ser)- enriched phosphorylated TDP-43 protein aggregation appears in the spinal cord of ALS animal models, and may be linked to the reduced phosphatase activity of Cn. The mutant overexpressed SOD1G93A protein does not properly bind zinc (Zn) in animal models; hence, mutant SOD1G93A-Cn interaction weakens. Consequently, unstable Cn fails to dephosphorylate TDP-43 that yields hyperphosphorylated TDP-43 aggregates. Our previous studies had suggested that Cn and SOD1 interaction was necessary to keep Cn enzyme functional. We have observed low Cn level, increased Zn concentrations, and increased TDP-43 protein levels in cervical, thoracic, lumbar, and sacral regions of the spinal cord tissue homogenates. This study further supports our previously published work indicating that Cn stability depends on functional Cn-SOD1 interaction because Zn is crucial for maintaining the Cn stability. Less active Cn did not efficiently dephosphorylate TDP-43; hence TDP-43 aggregations appeared in the spinal cord tissue.

ID: 29354481
Title: Disorders of metal metabolism.
Abstract: Trace elements are chemical elements needed in minute amounts for normal physiology. Some of the physiologically relevant trace elements include iodine, copper, iron, manganese, zinc, selenium, cobalt and molybdenum. Of these, some are metals, and in particular, transition metals. The different electron shells of an atom carry different energy levels, with those closest to the nucleus being lowest in energy. The number of electrons in the outermost shell determines the reactivity of such an atom. The electron shells are divided in sub-shells, and in particular the third shell has s, p and d sub-shells. Transition metals are strictly defined as elements whose atom has an incomplete d sub-shell. This incomplete d sub-shell makes them prone to chemical reactions, particularly redox reactions. Transition metals of biologic importance include copper, iron, manganese, cobalt and molybdenum. Zinc is not a transition metal, since it has a complete d sub-shell. Selenium, on the other hand, is strictly speaking a nonmetal, although given its chemical properties between those of metals and nonmetals, it is sometimes considered a metalloid. In this review, we summarize the current knowledge on the inborn errors of metal and metalloid metabolism.

ID: 29358575
Title: Pathological hydrogen peroxide triggers the fibrillization of wild-type SOD1 via sulfenic acid modification of Cys-111.
Abstract: Amyotrophic lateral sclerosis (ALS) involves the abnormal posttranslational modifications and fibrillization of copper, zinc superoxide dismutase (SOD1) and TDP-43. However, how SOD1-catalyzed reaction product hydrogen peroxide affects amyloid formation of SOD1 and TDP-43 remains elusory. 90% of ALS cases are sporadic and the remaining cases are familial ALS. In this paper, we demonstrate that H2O2 at pathological concentrations triggers the fibrillization of wild-type SOD1 both in vitro and in SH-SY5Y cells. Using an anti-dimedone antibody that detects sulfenic acid modification of proteins, we found that Cys-111 in wild-type SOD1 is oxidized to C-SOH by pathological concentration of H2O2, followed by the formation of sulfenic acid modified SOD1 oligomers. Furthermore, we show that such SOD1 oligomers propagate in a prion-like manner, and not only drive wild-type SOD1 to form fibrils in the cytoplasm but also induce cytoplasm mislocalization and the subsequent fibrillization of wild-type TDP-43, thereby inducing apoptosis of living cells. Thus, we propose that H2O2 at pathological concentrations triggers the fibrillization of wild-type SOD1 and subsequently induces SOD1 toxicity and TDP-43 toxicity in neuronal cells via sulfenic acid modification of Cys-111 in SOD1. Our Western blot and ELISA data demonstrate that sulfenic acid modified wild-type SOD1 level in cerebrospinal fluid of 15 sporadic ALS patients is significantly increased compared with 6 age-matched control patients. These findings can explain how H2O2 at pathologic concentrations regulates the misfolding and toxicity of SOD1 and TDP-43 associated with ALS, and suggest that sulfenic acid modification of wild-type SOD1 should play pivotal roles in the pathogenesis of sporadic ALS.

ID: 30559290
Title: SLC30A10 transporter in the digestive system regulates brain manganese under basal conditions while brain SLC30A10 protects against neurotoxicity.
Abstract: The essential metal manganese becomes neurotoxic at elevated levels. Yet, the mechanisms by which brain manganese homeostasis is regulated are unclear. Loss-of-function mutations in SLC30A10, a cell surface-localized manganese efflux transporter in the brain and liver, induce familial manganese neurotoxicity. To elucidate the role of SLC30A10 in regulating brain manganese, we compared the phenotypes of whole-body and tissue-specific Slc30a10 knockout mice. Surprisingly, unlike whole-body knockouts, brain manganese levels were unaltered in pan-neuronal/glial Slc30a10 knockouts under basal physiological conditions. Further, although transport into bile is a major route of manganese excretion, manganese levels in the brain, blood, and liver of liver-specific Slc30a10 knockouts were only minimally elevated, suggesting that another organ compensated for loss-of-function in the liver. Additional assays revealed that SLC30A10 was also expressed in the gastrointestinal tract. In differentiated enterocytes, SLC30A10 localized to the apical/luminal domain and transported intracellular manganese to the lumen. Importantly, endoderm-specific knockouts, lacking SLC30A10 in the liver and gastrointestinal tract, had markedly elevated manganese levels in the brain, blood, and liver. Thus, under basal physiological conditions, brain manganese is regulated by activity of SLC30A10 in the liver and gastrointestinal tract, and not the brain or just the liver. Notably, however, brain manganese levels of endoderm-specific knockouts were lower than whole-body knockouts, and only whole-body knockouts exhibited manganese-induced neurobehavioral defects. Moreover, after elevated exposure, pan-neuronal/glial knockouts had higher manganese levels in the basal ganglia and thalamus than controls. Therefore, when manganese levels increase, activity of SLC30A10 in the brain protects against neurotoxicity.

ID: 30714133
Title: Involvement of the synapse-specific zinc transporter ZnT3 in cadmium-induced hippocampal neurotoxicity.
Abstract: The present study examined the involvement of zinc (Zn)-transporters (ZnT3) in cadmium (Cd)-induced alterations of Zn homeostasis in rat hippocampal neurons. We treated primary rat hippocampal neurons for 24 or 48 hr with various concentrations of CdCl2 (0, 0.5, 5, 10, 25, or 50 μM) and/or ZnCl 2 (0, 10, 30, 50, 70, or 90 μM), using normal neuronal medium as control. By The CellTiter 96 ® Aqueous One Solution Cell Proliferation Assay (MTS; Promega, Madison, WI) assay and immunohistochemistry for cell death markers, 10 and 25 μM of Cd were found to be noncytotoxic doses, and both 30 and 90 μM of Zn as the best concentrations for cell proliferation. We tested these selected doses. Cd, at concentrations of 10 or 25 μM (and depending on the absence or presence of Zn), decreased the percentage of surviving cells. Cd-induced neuronal death was either apoptotic or necrotic depending on dose, as indicated by 7-AAD and/or annexin V labeling. At the molecular level, Cd exposure induced a decrease in hippocampal brain-derived neurotrophic factor-tropomyosin receptor kinase B (BDNF-TrkB) and Erk1/2 signaling, a significant downregulation of the expression of learning- and memory-related receptors and synaptic proteins such as the NMDAR NR2A subunit and PSD-95, as well as the expression of the synapse-specific vesicular Zn transporter ZnT3 in cultured hippocampal neurons. Zn supplementation, especially at the 30 μM concentration, led to partial or total protection against Cd neurotoxicity both with respect to the number of apoptotic cells and the expression of several genes. Interestingly, after knockdown of ZnT3 by small interfering RNA transfection, we did not find the restoration of the expression of this gene following Zn supplementation at 30 μM concentration. These data indicate the involvement of ZnT3 in the mechanism of Cd-induced hippocampal neurotoxicity.

ID: 31089831
Title: Genetic Disorders of Manganese Metabolism.
Abstract: This article provides an overview of the pathogenesis, clinical presentation and treatment of inherited manganese transporter defects. Identification of a new group of manganese transportopathies has greatly advanced our understanding of how manganese homeostasis is regulated in vivo. While the manganese efflux transporter SLC30A10 and the uptake transporter SLC39A14 work synergistically to reduce the manganese load, SLC39A8 has an opposing function facilitating manganese uptake into the organism. Bi-allelic mutations in any of these transporter proteins disrupt the manganese equilibrium and lead to neurological disease: Hypermanganesaemia with dystonia 1 (SLC30A10 deficiency) and hypermanganesaemia with dystonia 2 (SLC39A14 deficiency) are characterised by manganese neurotoxicity while SLC39A8 mutations cause a congenital disorder of glycosylation type IIn due to Mn deficiency. Inherited manganese transporter defects are an important differential diagnosis of paediatric movement disorders. Manganese blood levels and MRI brain are diagnostic and allow early diagnosis to avoid treatment delay.

ID: 31759136
Title: Synaptic zinc contributes to motor and cognitive deficits in 6-hydroxydopamine mouse models of Parkinson's disease.
Abstract: Hyperactivity of glutamatergic corticostrial pathways is recognized as a key pathophysiological mechanism contributing to development of PD symptoms and dopaminergic neurotoxicity. Subset of corticostriatal projection neurons uses Zn2+ as a co-transmitter alongside glutamate, but the role of synaptically released Zn2+ in PD remains unexplored. We used genetically modified mice and pharmacological tools in combination with 6-hydroxydopamine (6-OHDA) lesion models of PD to investigate the contribution of synaptic zinc to disease associated behavioral deficits and neurodegeneration. Vesicular zinc transporter-3 (ZnT3) knockout mice lacking releasable Zn2+ were more resistant to locomotor deficit and memory impairment of nigrostriatal dopamine (DA) denervation compared to wildtype littermates. The loss of striatal dopaminergic fibers was comparable between genotypes, indicating that synaptically released Zn2+ contributes to behavioral deficits but not neurotoxic effects of 6-OHDA. To gain further insight into the mechanisms of Zn2+ actions, we used the extracellular Zn2+ chelator CaEDTA and knock-in mice lacking the high affinity Zn2+ inhibition of GluN2A-containing NMDA receptors (GluN2A-NMDARs). Acute chelation of extracellular Zn2+ in the striatum restored locomotor deficit of 6-OHDA lesion, confirming that synaptic Zn2+ suppresses locomotor behavior. Disruption of the Zn2+-GluN2A interaction had, on the other hand, no impact on locomotor deficit or neurotoxic effect of 6-OHDA. Collectively, these findings provide clear evidence for the implication of striatal synaptic Zn2+ in the pathophysiology of PD. They unveil that synaptic Zn2+ plays predominantly a detrimental role by promoting motor and cognitive deficits caused by nigrostriatal DA denervation, pointing towards new therapeutic interventions.

ID: 32599739
Title: MicroRNA-5572 Is a Novel MicroRNA-Regulating SLC30A3 in Sporadic Amyotrophic Lateral Sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disease caused by the loss of motor neurons. Although the pathogenesis of sporadic ALS (sALS) remains unclear, it has recently been suggested that disorders of microRNA (miRNA) may be involved in neurodegenerative conditions. The purpose of this study was to investigate miRNA levels in sALS and the target genes of miRNA. Microarray and real-time RT-PCR analyses revealed significantly-decreased levels of miR-139-5p and significantly increased levels of miR-5572 in the spinal cords of sALS patients compared with those in controls. We then focused on miR-5572, which has not been reported in ALS, and determined its target gene. By using TargetScan, we predicted SLC30A3 as the candidate target gene of miR-5572. In a previous study, we found decreased SLC30A3 levels in the spinal cords of sALS patients. We revealed that SLC30A3 was regulated by miR-5572. Taken together, these results demonstrate that the level of novel miRNA miR-5572 is increased in sALS and that SLC30A3 is one of the target genes regulated by miR-5572.

ID: 33260324
Title: Zinc Binds to RRM2 Peptide of TDP-43.
Abstract: Transactive response DNA and RNA binding protein 43 kDa (TDP-43) is a highly conserved heterogeneous nuclear ribonucleoprotein (hnRNP), which is involved in several steps of protein production including transcription and splicing. Its aggregates are frequently observed in motor neurons from amyotrophic lateral sclerosis patients and in the most common variant of frontotemporal lobar degeneration. Recently it was shown that TDP-43 is able to bind Zn2+ by its RRM domain. In this work, we have investigated Zn2+ binding to a short peptide 256-264 from C-terminus of RRM2 domain using isothermal titration calorimetry, electrospray ionization mass spectrometry, QM/MM simulations, and NMR spectroscopy. We have found that this peptide is able to bind zinc ions with a Ka equal to 1.6 × 105 M-1. Our findings suggest the existence of a zinc binding site in the C-terminal region of RRM2 domain. Together with the existing structure of the RRM2 domain of TDP-43 we propose a model of its complex with Zn2+ which illustrates how zinc might regulate DNA/RNA binding.

ID: 33297139
Title: In-vitro and in-vivo evaluation of the molecular mechanisms involved in the toxicity associated to CdSe/ZnS quantum dots exposure.
Abstract: The use of different types of quantum dots is growing in recent times in both the technology and biomedical industries. Such is the extension of the use of these quantum dots that they have become potential emerging contaminants, which makes it necessary to evaluate their potential toxicity and the impact they may have on both health and the environment. Although studies already exist in this regard, the molecular mechanisms by which CdSe/ZnS quantum dots exert their toxic effects are still unknown. For this reason, in this study, a comprehensive proteomic approach has been designed, applying the SILAC strategy to an in-vitro model (hepatic cells) and the super-SILAC alternative to an in-vivo model, specifically zebrafish larvae. This integral approach, together with additional bioanalytical assays, has made it possible for the identification of proteins, molecular mechanisms and, therefore, biological processes that are altered as a consequence of exposure to CdSe/ZnS quantum dots. It has been demonstrated, on the one hand, that these quantum dots induce hypoxia and ROS generation in hepatic cells, which leads to apoptosis, specifically through the TDP-43 pathway. On the other hand, it has been shown that exposure to CdSe/ZnS quantum dots has a high impact on developing organisms, inducing serious neural and developmental problems in the locomotor system.

ID: 33723228
Title: The E50K optineurin mutation impacts autophagy-mediated degradation of TDP-43 and leads to RGC apoptosis in vivo and in vitro.
Abstract: The glaucoma-associated E50K mutation in optineurin (OPTN) is known to affect autophagy and cause the apoptosis of retinal ganglion cells (RGCs), but the pathogenic mechanism remains unclear. In this study, we investigated whether the OPTN (E50K) mutation caused TDP-43 aggregation by disrupting autophagy in vivo and in vitro. OPTN (E50K) mutant mice were generated and analysed for genotype and phenotype. Adeno-associated virus type 2 vectors containing either GFP only, GFP-tagged wild-type OPTN or GFP-tagged E50K-mutated OPTN were used to transfect R28 cells. Loss of RGCs decreased retinal thickness and visual impairment were observed in OPTN (E50K) mice compared with WT mice. Moreover, overexpression of E50K OPTN induced R28 cell apoptosis. Increased p62/SQSTM1 and LC3-II levels indicated that autophagic flux was inhibited and contributed to TDP-43 aggregation in vivo and in vitro. We found that rapamycin effectively reduced the aggregation of TDP-43 in OPTN (E50K) mice and decreased the protein levels of p62/SQSTM1 and the autophagic marker LC3-II. Moreover, rapamycin increased the RGC number and visual function of E50K mice. In addition, we also observed increased cytoplasmic TDP-43 in the spinal cord and motor dysfunction in 24-month-old OPTN (E50K) mice, indicating that TDP-43 accumulation may be the common pathological mechanism of glaucoma and amyotrophic lateral sclerosis (ALS). In conclusion, the disruption of autophagy by OPTN (E50K) affected the degradation of TDP-43 and may play an important role in OPTN (E50K)-mediated glaucomatous retinal neurodegeneration.

ID: 33946908
Title: Synaptic Zinc: An Emerging Player in Parkinson's Disease.
Abstract: Alterations of zinc homeostasis have long been implicated in Parkinson's disease (PD). Zinc plays a complex role as both deficiency and excess of intracellular zinc levels have been incriminated in the pathophysiology of the disease. Besides its role in multiple cellular functions, Zn2+ also acts as a synaptic transmitter in the brain. In the forebrain, subset of glutamatergic neurons, namely cortical neurons projecting to the striatum, use Zn2+ as a messenger alongside glutamate. Overactivation of the cortico-striatal glutamatergic system is a key feature contributing to the development of PD symptoms and dopaminergic neurotoxicity. Here, we will cover recent evidence implicating synaptic Zn2+ in the pathophysiology of PD and discuss its potential mechanisms of actions. Emphasis will be placed on the functional interaction between Zn2+ and glutamatergic NMDA receptors, the most extensively studied synaptic target of Zn2+.

ID: 34380651
Title: Critical Role of Zinc Transporter (ZIP8) in Myeloid Innate Immune Cell Function and the Host Response against Bacterial Pneumonia.
Abstract: Zinc (Zn) is required for proper immune function and host defense. Zn homeostasis is tightly regulated by Zn transporters that coordinate biological processes through Zn mobilization. Zn deficiency is associated with increased susceptibility to bacterial infections, including Streptococcus pneumoniae, the most commonly identified cause of community-acquired pneumonia. Myeloid cells, including macrophages and dendritic cells (DCs), are at the front line of host defense against invading bacterial pathogens in the lung and play a critical role early on in shaping the immune response. Expression of the Zn transporter ZIP8 is rapidly induced following bacterial infection and regulates myeloid cell function in a Zn-dependent manner. To what extent ZIP8 is instrumental in myeloid cell function requires further study. Using a novel, myeloid-specific, Zip8 knockout model, we identified vital roles of ZIP8 in macrophage and DC function upon pneumococcal infection. Administration of S. pneumoniae into the lung resulted in increased inflammation, morbidity, and mortality in Zip8 knockout mice compared with wild-type counterparts. This was associated with increased numbers of myeloid cells, cytokine production, and cell death. In vitro analysis of macrophage and DC function revealed deficits in phagocytosis and increased cytokine production upon bacterial stimulation that was, in part, due to increased NF-κB signaling. Strikingly, alteration of myeloid cell function resulted in an imbalance of Th17/Th2 responses, which is potentially detrimental to host defense. These results (for the first time, to our knowledge) reveal a vital ZIP8- and Zn-mediated axis that alters the lung myeloid cell landscape and the host response against pneumococcus.

ID: 35389887
Title: The ZIP8/SIRT1 axis regulates alveolar progenitor cell renewal in aging and idiopathic pulmonary fibrosis.
Abstract: Type 2 alveolar epithelial cells (AEC2s) function as progenitor cells in the lung. We have shown previously that failure of AEC2 regeneration results in progressive lung fibrosis in mice and is a cardinal feature of idiopathic pulmonary fibrosis (IPF). In this study, we identified deficiency of a specific zinc transporter, SLC39A8 (ZIP8), in AEC2s from both IPF lungs and lungs of old mice. Loss of ZIP8 expression was associated with impaired renewal capacity of AEC2s and enhanced lung fibrosis. ZIP8 regulation of AEC2 progenitor function was dependent on SIRT1. Replenishment with exogenous zinc and SIRT1 activation promoted self-renewal and differentiation of AEC2s from lung tissues of IPF patients and old mice. Deletion of Zip8 in AEC2s in mice resulted in impaired AEC2 renewal, increased susceptibility to bleomycin injury, and development of spontaneous lung fibrosis. Therapeutic strategies to restore zinc metabolism and appropriate SIRT1 signaling could improve AEC2 progenitor function and mitigate ongoing fibrogenesis.

ID: 39153533
Title: TDP-43 ameliorates aging-related cartilage degradation through preventing chondrocyte senescence.
Abstract: Senescent chondrocytes or signaling mechanisms leading to senescence are promising new therapeutic approaches for ameliorating cartilage degradation. Herein, we show that the transactive response DNA/RNA-binding protein (TDP-43) regulates chondrocyte senescence and ameliorates cartilage degradation. First, a significant decrease in TDP-43 was observed in 16-month-old mice compared with younger mice. Immunohistochemistry (IHC) analysis of mouse articular cartilage showed that p21, p16, p53, and matrix metalloprotein-13 (MMP13) were increased, but laminB1 and Collagen type II alpha1 1 chain (Col2a1) were decreased in 16-month-old mice. Furthermore, TDP-43 levels were decreased in vivo following D-galactose (D-gal) induction. Therefore, we investigated the role of TDP-43 in the senescent chondrocytes. ATDC5 cells were induced to overexpress TDP-43. Western blot analysis showed increased expression of laminB1, Ki67, and PCNA but decreased expression of p21, p16, p53, and MMP13. Senescence-associated-β-galactosidase (SA-β-Gal) assay, γH2AX staining, and EdU were performed to assess changes in chondrocytes, showing weaker SA-β-Gal and γH2AX staining but stronger EdU and Alican Blue staining. However, TDP-43 deficiency had opposing effects, and similar to D-gal stimulation results. Taken together, our data verified that TDP-43 negatively correlated with senescence markers, positively correlated with cell proliferation markers, and could alleviate cartilage degradation induced by D-gal. This may be an essential mechanism of cellular senescence and cartilage degradation.

ID: 40392845
Title: Stathmin-2 enhances motor axon regeneration after injury independent of its binding to tubulin.
Abstract: Stathmin-2 (also known as SCG10) is encoded by the STMN2 gene, whose mRNA is one of the most abundantly expressed in human motor neurons. In almost all instances of ALS and other TDP-43 proteinopathies, stathmin-2 encoding mRNAs are cryptically spliced and polyadenylated in motor neurons, a pathogenic consequence of nuclear loss of function of the RNA binding protein TDP-43. While stathmin-2 has been shown to enhance regeneration after axonal injury to axons of cultured motor neurons, here, we show that after crush injury within the adult murine nervous system of wild-type or stathmin-2-null mice, the presence of stathmin-2 reduces axonal and neuromuscular junction degeneration and stimulates reinnervation and functional recovery. Mechanistically, although stathmin-2 has been proposed to function through direct binding to α/β tubulin heterodimers and correspondingly to affect microtubule assembly and dynamics, stathmin-2's role in axon regeneration after axotomy is shown to be independent of its tubulin binding abilities.

ID: 40717725
Title: Thalamic nuclei volumes are related to disease stage in patients with amyotrophic lateral sclerosis.
Abstract: To explore atrophy patterns in thalamic nuclei at different phases of amyotrophic lateral sclerosis (ALS) and determine any correlations between thalamic nucleus volume and either cognitive impairments or motor disabilities. We used the King's clinical staging system for ALS to divide 76 consecutive patients with ALS by disease stage. We investigated patterns of thalamic atrophy in the patients and in 94 healthy controls (HCs). Cognitive functions were evaluated with the Mini-Mental State Examination (MMSE), Frontal Assessment Battery, Boston Naming Test, and Auditory Verbal Learning Test. Considering all ALS patients, no significant differences were observed in the volume of any thalamic nuclei between the ALS group and HCs. Thalamic nucleus volumes remained normal in ALS patients at King's Stage 2 and Stage 3. However, atrophy was detected in the bilateral anteroventral nucleus, bilateral pulvinar-limitans, bilateral mediodorsal-paratenial-reuniens, bilateral motor hub, bilateral sensory hub, and bilateral intralaminar nucleus in patients who had reached King's Stage 3. In these patients, the volume of the bilateral motor nuclei was associated with the revised ALS Functional Rating Scale scores, and that of the right pulvinar-limitans independently correlated with MMSE scores. Our study provides a comprehensive profile of thalamic atrophy in ALS patients. The thalamic atrophy patterns in these patients extremely differs at different King's Stages, and we suggest that these alterations might result largely from sequential, regional patterns of TDP-43 pathology in ALS. Furthermore, thalamic atrophy might play important roles in motor disability and global cognitive impairments observed in patients with ALS.

ID: 40949955
Title: Cryptic splicing in synaptic and membrane excitability genes links TDP-43 loss to neuronal dysfunction.
Abstract: TDP-43 pathology is a defining pathological hallmark of multiple neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A major feature of TDP-43 pathology is its nuclear depletion, leading to the aberrant inclusion of cryptic exons during RNA splicing. STMN2 and UNC13A have emerged as prominent TDP-43 splicing targets, but the broader impact of TDP-43-dependent cryptic splicing on neuronal function remains unclear. Here, we report new TDP-43 splicing targets critical for membrane excitability and synaptic function, including KALRN, RAP1GAP, SYT7 and KCNQ2. Using human stem cell-derived neurons, we show that TDP-43 reduction induces cryptic splicing and downregulation of these genes, resulting in impaired excitability and synaptic transmission. In postmortem brains from patients with FTD, these cryptic splicing events occur selectively in neurons with TDP-43 pathology. Importantly, suppressing individual cryptic splicing events using antisense oligonucleotides partially restores neuronal function, and combined targeting almost fully rescues the synaptic deficit caused by TDP-43 loss. Together, our findings provide evidence that cryptic splicing in these synaptic and membrane excitability genes is not only a downstream marker but instead a direct driver of neuronal dysfunction, establishing a mechanistic link between TDP-43 pathology and neurodegeneration in ALS and FTD.

ID: 41121980
Title: Quantifying subpercent nuclear TDP-43 loss in cells and ALS cortex using junction-specific cryptic exon RT-qPCR.
Abstract: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are progressive neurodegenerative diseases characterised by nuclear TDP-43 loss. Its hallmark, cryptic exon (CE) splicing, is often masked in bulk tissue analyses by the low abundance of affected neurons. We developed an ultrasensitive RT-qPCR assay targeting STMN2 CE using one exon-CE junction-spanning primer and the other within the CE. The design expands the dynamic range sevenfold: TDP-43 knockdown boosted STMN2 CE levels 1395-fold in differentiated SH-SY5Y neurons. Spike-in tests set detection at 0.16% deficient cells. Crucially, the assay revealed a 42-fold CE increase in ALS motor cortex, previously missed by conventional primers. This streamlined tool enables precise quantification of TDP-43 dysfunction and sensitive pharmacodynamic monitoring for future ALS-FTD therapeutic studies. Impact statement Because cryptic-exon signals are diluted in bulk tissue, we developed a junction-spanning STMN2 RT-qPCR with sub-percent sensitivity. This deployable biomarker will aid ALS/FTD researchers and drug developers by standardizing measurements and enabling sensitive pharmacodynamic monitoring of therapies targeting nuclear TDP-43 dysfunction.

ID: 41180957
Title: Vitreous STMN2 levels reflect TDP-43-associated neurodegeneration in postmortem eyes and brains.
Abstract: Stathmin-2 (STMN2) levels decline in brains with transactive response DNA binding protein-43 (TDP-43) inclusions. TDP-43-related changes could extend to ocular structures, although vitreous STMN2 levels remain uncharacterized. This exploratory study analyzed 72 post-mortem brains and eyes depending on the presence or absence of TDP-43 inclusions in the brain and across neuropathological diagnostic groups (Alzheimer's disease [AD], chronic traumatic encephalopathy [CTE], AD and CTE, or neither). Results showed decreased vitreous STMN2 levels in TDP-43-positive cases but no association with diagnostic groups. Vitreous STMN2 was correlated with vitreous neurofilament light chain. Diminished vitreous STMN2 levels might indicate TDP-43-associated neurodegeneration.

ID: 41256495
Title: Skin TDP-43 pathology as a candidate biomarker for predicting amyotrophic lateral sclerosis decades prior to motor symptom onset.
Abstract: The recognition that disease-associated proteinopathies can manifest in peripheral organs outside the central nervous system preceding the onset of neurological symptoms, has transformed our understanding of Parkinson's disease, in wide terms of pathogenesis, detection and diagnosis. For amyotrophic lateral sclerosis, non-motor symptoms, and non-central nervous system pathologies are gaining increased recognition but remain incompletely understood. Here, using a TDP-43 RNA aptamer and a Stathmin-2 cryptic exon transcript BaseScope™ ISH probe, we identify widespread peripheral organ TDP-43 pathology prior to motor symptom onset in a discovery cohort of ante-mortem tissues from people who went on to develop ALS. Peripheral organs exhibiting both TDP-43 toxic gain- and loss-of function include muscle, lymph node, gallbladder, colon and with notably high incidence, skin. Given the accessibility of skin as a readily biopsiable tissue, representing a promising substrate for the detection of disease-associated proteinopathies and the development of minimally invasive biomarkers, we established an extended cohort of ante-mortem skin samples for TDP-43 pathology validation and further investigation. In skin biopsies taken during life from 17 individuals who went on to develop ALS we identify TDP-43 pathology from all 17 individuals in a wide distribution of anatomical sites, up to 26.5 years before ALS diagnosis - a presymptomatic period comparable to that observed for skin α-synucleinopathy in Parkinson's disease. TDP-43 pathology was most abundant in skin biopsies from the back and shoulder, with sweat and sebaceous glands showing the highest involvement. TDP-43 pathology was also associated with structural changes. As skin α-synucleinopathy has been established as a biomarker for both the detection of Parkinson's disease and the differentiation of Parkinson's disease from multiple system atrophy, we propose that skin TDP-43 likewise holds diagnostic and discrimination potential for diseases characterised by TDP-43 proteinopathy.

ID: 41300833
Title: SLC30A3 as a Zinc Transporter-Related Biomarker and Potential Therapeutic Target in Alzheimer's Disease.
Abstract: Alzheimer's disease (AD) is a progressive neurodegenerative disorder with unclear pathogenic mechanisms. Dysregulated zinc metabolism contributes to AD pathology. This study aimed to identify zinc metabolism-related hub genes to provide potential biomarkers and therapeutic targets for AD. We performed an integrative analysis of multiple transcriptomic datasets from AD patients and normal controls. Differentially expressed genes and weighted gene co-expression network analysis (WGCNA) were combined to identify hub genes. We then conducted Gene Set Enrichment Analysis (GSEA), immune cell infiltration analysis (CIBERSORT), and receiver operating characteristic (ROC) curve analysis to assess the hub gene's biological function, immune context, and diagnostic performance. Drug-gene interactions were predicted using the DrugBank database. We identified a single key zinc transporter-related hub gene, SLC30A3, which was significantly downregulated in AD and demonstrated potential diagnostic value (AUC 0.70-0.80). Lower SLC30A3 expression was strongly associated with impaired synaptic plasticity (long-term potentiation, long-term depression, calcium signaling pathway, and axon guidance), mitochondrial dysfunction (the citrate cycle and oxidative phosphorylation), and pathways common to major neurodegenerative diseases (Parkinson's disease, AD, Huntington's disease, and amyotrophic lateral sclerosis). Furthermore, SLC30A3 expression correlated with specific immune infiltrates, particularly the microglia-related chemokine CX3CL1. Zinc chloride and zinc sulfate were identified as potential pharmacological modulators. Our study systematically identifies SLC30A3 as a novel biomarker in AD, linking zinc dyshomeostasis to synaptic failure, metabolic impairment, and neuroimmune dysregulation. These findings offer a new basis for developing targeted diagnostic and therapeutic strategies for AD.

ID: 41379352
Title: Distinct cerebrovascular pathways underlying Alzheimer's disease-related neurodegeneration.
Abstract: The etiology of cerebrovascular pathology is heterogeneous. Independent or synergistic role of this pathology relative to Alzheimer's disease (AD) pathology is necessary to clarify distinct neurodegenerative pathways. We evaluated the interplay of various cerebrovascular markers postmortem and their in vivo neuroimaging, clinical and neuropathologic correlates using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI). In 109 individuals, postmortem cerebrovascular pathology (atherosclerosis of the circle of Willis, cerebral amyloid angiopathy [CAA], arteriolosclerosis, white matter rarefaction, old infarcts, microinfarcts, hemorrhages, other ischemic/vascular changes) was characterized. Additionally, we assessed in vivo neuroimaging (cortical thickness, subcortical volume, white matter lesion burden, glucose standardized uptake value ratio, fractional anisotropy of white matter tracts, cerebral blood flow), cognitive, and neuropathologic measures (atrophy, AD pathology and copathologies including Lewy body, TDP-43, hippocampal sclerosis). The study sample had mean (standard deviation) age of 82.9 (7.2) years and included 29 women (27%) and 84 (77%) with intermediate/high AD neuropathologic change. Arteriolosclerosis and CAA emerged as dominant cerebrovascular markers using multiple correspondence analysis. More severe arteriolosclerosis was explained by higher white matter lesion burden and greater postmortem hippocampal atrophy (β = 143.2, 95% CI 63.9 to 230.1, p = 0.0003), but not AD pathology. More severe CAA was explained by fractional anisotropy (β = - 20, 95% CI - 41.5 to -3.1, p = 0.02) adjusted for AD pathology and reduced integrity of superior cerebellar peduncle, posterior thalamic radiation, and sagittal stratum tracts (rho < - 0.6, false discovery rate corrected p < 0.05). More severe CAA was also explained by cortical atrophy and AD pathology (β = 0.6, 95% CI 0.2 to 1.2, p = 0.007), and associated with poorer memory (β = - 0.2, 95% CI - 0.3 to -0.09, p = 0.0009). Results demonstrate two dominant cerebrovascular pathways. An arteriolosclerosis-driven pathway is unspecific to AD pathology, whereas a CAA-driven pathway is specific to AD pathology. Cerebrovascular pathology is associated with AD pathology in an etiology-dependent manner which may influence eligibility for treatment or treatment-emergent adverse events in disease-modifying therapies for AD.

ID: 41426430
Title: The role of disease-associated short tandem repeats in amyotrophic lateral sclerosis.
Abstract: Short tandem repeats (STRs) are recognized contributors to various neurodegenerative disorders, with evidence supporting genetic pleiotropy among these STRs. Multiple STRs have been associated with amyotrophic lateral sclerosis (ALS), although the strength of evidence supporting each association varies. To establish the role of disease-associated repeat expansions as pleiotropic risk factors in ALS susceptibility and progression, we genotyped a panel of 39 STRs, known to cause neurological diseases, within Project MinE in 6519 patients and 2412 controls, utilizing 100 and 150 bp short-read sequencing technology. Pathogenic allele frequencies were compared to those in a control cohort comprising 4930 Genome Aggregation Database (gnomAD) genomes. Repeat sizes and motif changes were detected using ExpansionHunter and ExpansionHunter Denovo. We developed a model to predict genotyping failures in STRs and established a best-practice protocol for assessing the accuracy of STR genotyping in short-read sequencing data. Following our genotyping assessment, 11 out of the 39 STRs exhibited insufficient genotyping accuracy, warranting caution in studying these STRs using these tools in combination with short-read sequencing. Furthermore, the observed differences in STR genotyping accuracy across studies applying different sequencing technologies and genotyping tools in control cohorts highlight the importance of a carefully designed experimental setup when interpreting potential disease-associated STR findings. Pathogenic C9orf72 and premutated ATXN2 expansions were confirmed to be significantly associated with ALS susceptibility. Additionally, pathogenic C9orf72 expansions were significantly associated with reduced mean ALS survival by 11.5 months and an earlier mean age at onset by 2.4 years. Premutation expansions in ATXN1 showed a nominally significant association with ALS susceptibility, while pathogenic expansions in NIPA1 displayed a nominally significant association with ALS survival. Previously reported ALS-associated pleiotropy in HTT and STMN2 could not be confirmed. Motif changes were identified in BEAN1, RFC1, ATXN8, C9orf72, DAB1, FXN and SAMD12; however, none of the motif changes were linked to ALS. Re-evaluation of clinical data from patients with ALS and a repeat expansion typically associated with another disease revealed that 7% of these patients' diagnoses had to be reclassified to the disease associated with the repeat expansion (e.g. Kennedy's disease or spinocerebellar ataxia). This underscores the value of broad STR screening in neurodegenerative cases. Pathogenic and premutation STRs were also found in controls in unexpected high frequencies, suggesting reduced penetrance or underdiagnosis, and highlighting the need for caution when interpreting genetic associations with disease without a proper control cohort.

ID: 41490046
Title: TDP-43-mediated alternative polyadenylation is associated with a reduction in VPS35 and VPS29 expression in frontotemporal dementia.
Abstract: TAR DNA-binding protein 43 (TDP-43) dysfunction is a hallmark of several neurodegenerative diseases, including frontotemporal dementia, amyotrophic lateral sclerosis, and Alzheimer's disease. Although cryptic exon inclusion is a well-characterized consequence of TDP-43 loss of function, emerging evidence reveals broader roles in RNA metabolism, notably in the regulation of alternative polyadenylation (APA) of disease-relevant transcripts. In the present study, we examined 3' untranslated region lengthening events in the brains of individuals with frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP), focusing on the functional impact of APA dysregulation. To investigate whether TDP-43-mediated APA events occur in the postmortem brain, we measured the 3' untranslated region length of the retromer component vacuolar protein sorting 35 (VPS35) and the ETS transcription factor (ELK1) in the frontal cortex of a large cohort of FTLD-TDP patients and of healthy controls, and evaluated if these APA events are associated with FTLD-TDP clinical characteristic, markers of TDP-43 pathology [e.g., hyperphosphorylated TDP-43 and cryptic stathmin-2 RNA], or the expression of VPS35 and VPS29 proteins, the latter being essential to the retromer complex. We identified robust 3' untranslated region lengthening of VPS35 and ELK1 in FTLD-TDP, which strongly associated with markers of TDP-43 pathology, and ELK1 APA also associated with an earlier age of disease onset. Functionally, VPS35 APA was associated with reduced VPS35 and VPS29 protein expression, and lower VPS35 levels were associated with increased hyperphosphorylated TDP-43 and cryptic stathmin-2 RNA. Together, these data implicate APA dysregulation as a critical downstream consequence of TDP-43 dysfunction and suggest that TDP-43 loss may contribute to retromer impairment through APA-mediated repression of retromer subunits.

ID: 41509294
Title: Postmortem brain MRI reveals differential associations of subcortical and limbic volumes with cortical thinning and neuropathology patterns.
Abstract: The impact of different neuropathologies on deep brain structures remains to be understood. Here, we distinguish subcortical and limbic volumetry in neurodegenerative diseases involving p-tau, α-synuclein and TDP-43. We acquired neuropathological measures and brain segmentations from postmortem analysis of 132 donors with Alzheimer's disease (AD; n=60), Lewy body disease (LBD; n=26), Frontotemporal Lobar Degeneration with TDP-43 (FTLD-TDP; n=21) and FTLD-Tau (n=25). In FTLD-TDP and FTLD-Tau, thalamus and striatum volumes were lower than in AD or LBD. While AD had diffuse cortico-subcortical and cortico-limbic morphometric associations, LBD had more limited parieto-occipital cortico-limbic associations. FTLD-TDP had cortico-subcortical associations while FTLD-Tau had cortico-limbic associations. In AD and FTLD-Tau, hippocampal volumes correlated with p-tau burden, neuron loss and gliosis. In LBD, thalamic α-synuclein severity was associated with subcortical and limbic volumes. In FTLD-TDP, TDP-43 load had no such significant associations. Postmortem neuroimaging reveals unique structure-structure and structure-pathology relationships across regions and diseases.

ID: 41547996
Title: γ-Radiation induces region-specific subcellular alterations of amyotrophic lateral sclerosis and frontotemporal dementia markers in swine brain.
Abstract: Low-dose radiation (LDR) effects on the brain have been poorly investigated. Studies have also questioned whether radiation increases ALS risk. We assessed the expression levels of a series of proteins associated with ALS and ALS-FTD in the brains of swine exposed to low-dose radiation to explore this notion. Male Gottingen minipigs were exposed to a single total-body γ-radiation (1.79 Gy). After 28 days, brains from 9 RAD to 6 SH animals were collected. Using neuroanatomically based dissection and Western Blotting, we compared levels of ALS/ALS-FTD markers (SOD1, FUS/TLS, C9orf72, STMN2, ubiquitin, TDP43 (N and C terminal), and pTDP43) in RAD vs. SH animals in frontal cortex (FCtx), striatum (Str), hippocampus (Hip), thalamus/hypothalamus (Thal/Hyp), and cerebellum (Cere). Cytosolic FUS/TLS decreased in the Thal/Hyp and remained unchanged in all other regions; nuclear levels increased in the FCtx and decreased in the Hip of RAD vs. SH. Cytosolic C9orf72 remained unchanged across all brain regions; nuclear levels decreased in the Hip of RAD vs. SH. Cytosolic STMN2 remained unchanged in all brain regions and decreased in the nuclear fraction of the Hip of RAD vs. SH. Cytosolic and nuclear ubiquitin remained unchanged across brain regions, except for an increase in the FCtx. TDP-43 (N and C terminal) levels remained unchanged in cytosolic and nuclear fractions across all brain regions; finally, cytosolic pTDP43 (S403/404) increased in the FCtx, Str and Thal/Hyp of RAD vs. SH. LDR-induced ALS/ALS-FTD-marker changes differ across brain regions and subcellular compartments. These changes are not necessarily associated with increased activation or potentiation of the main molecular processes associated with ALS pathogenesis; surprisingly, they may produce beneficial effects.

ID: 41573891
Title: Dual-targeting snRNA gene therapy rescues STMN2 and UNC13A splicing in TDP-43 proteinopathies.
Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder caused by the selective deterioration of motor neurons in the central nervous system (CNS). A key driver of this pathogenesis is nuclear loss of ALS-associated protein TDP-43, leading to mis-splicing of TDP-43 targets including important neuronal genes STMN2 and UNC13A . Here, we have developed a gene therapy strategy for ALS and related TDP-43 proteinopathies, to correct mis-splicing of both STMN2 and UNC13A cryptic exons using small nuclear RNAs (snRNAs) encoded from a single vector. We identified promoter sequence elements to increase therapeutic snRNA expression by 10-fold, then further optimized the expression cassette with combinatorial snRNA targeting to rescue multiple cryptic splicing targets. The engineered snRNAs restored normal pre-mRNA processing of both STMN2 and UNC13A transcripts despite TDP-43 loss of function, rescuing stathmin-2 protein levels in iPSC derived motor neurons, restoring their axonal regeneration capacity to wild-type levels. In addition, adeno-associated virus (AAV) delivery of the snRNAs to the murine central nervous system in the constitutive cryptic splicing model Stmn2 HumΔGU fully restored cortical Stmn2 pre-mRNA processing, highlighting the utility of snRNAs as a therapeutic modality in vivo . Together, this study demonstrates that snRNAs are a promising and versatile therapeutic strategy for the simultaneous correction of multiple aberrant transcripts affected by cryptic splicing in TDP-43 proteinopathies.

ID: 41741685
Title: PML targets and resolves structured protein inclusions to mitigate neurodegeneration.
Abstract: Intranuclear inclusions are defining features of many neurodegenerative diseases, yet their assembly mechanisms and pathological roles remain poorly understood. Here, we investigate polyglycine (polyG) inclusions in neuronal intranuclear inclusion disease (NIID) and show that they recruit intrinsically disordered proteins to form stratified, immobile condensates that disrupt nuclear protein quality control and DNA damage repair. Leveraging their ordered and stepwise assembly, we identify promyelocytic leukaemia protein (PML) as a key factor that actively recognizes and eliminates polyG inclusions through chaperone-mediated disaggregation and proteasome-dependent degradation. Engineered PML variants selectively clear both nuclear and cytoplasmic aggregates, including polyG, polyGA, polyQ, TDP-43 and SOD1. Systemic PML delivery alleviates cognitive and motor deficits in mouse models of NIID and TDP-43 proteinopathy. These findings uncover a conserved spatial organization of nuclear inclusions and establish PML as a therapeutic effector for neurodegenerative diseases linked to protein aggregation.

ID: 41820797
Title: In vitro, cellular and in vivo studies of amyloid oligomers structure and toxicity: Challenges and advances.
Abstract: Oligomeric assemblies of amyloidogenic proteins, such as Aβ, tau, α-synuclein, amylin, transthyretin, and TDP-43, are increasingly recognized as key drivers of cellular dysfunction across a range of neurodegenerative and systemic disorders. However, their molecular properties remain poorly understood due to their low abundance, structural heterogeneity, and transient nature. This review outlines current methods for studying amyloid oligomers, including biophysical (NMR, cryo-EM, HS-AFM, mass spectrometry), computational (molecular dynamics simulations), and biological (cellular assays, organoids, and animal models) approaches. This review also covers emerging methods for detecting misfolded proteins within complex biological environments and live-cell systems. Furthermore, we discuss recent advances that specifically address the challenges of studying oligomers, which are yielding crucial data on how these pathogenic species impair cellular homeostasis. Given the heterogeneity and transient nature of the oligomers, it is essential to utilize findings across diverse experimental platforms that yield complementary data and apply methods that also ensure reproducibility and mechanistic clarity with the goal of translating these findings into effective therapeutic strategies.

ID: 41875078
Title: A quantitative cell-based reporter links TDP-43 aggregation and dysfunction to define pathogenic mechanisms.
Abstract: TDP-43 pathology is a hallmark of fatal neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and limbic-predominant age-related TDP-43-encephalopathy (LATE). In affected patients, cytoplasmic TDP-43 aggregates are accompanied by disruption of its normal nuclear localization and function. Because TDP-43 is an RNA binding protein that controls transcript processing, including repression of cryptic exon splicing, its loss leads to dysregulation of gene expression. Despite its central significance in disease, the connection between TDP-43 aggregation and dysfunction remains poorly understood, and models to study the underlying mechanisms are limited. Here, we characterize a robust and quantitative cell-based reporter that captures both aggregation and the resulting loss of function. Using this human biosensor cell line, we show that aggregation initiated by prion-like seeding drives progressive depletion of nuclear TDP-43 and induces signature features of diminished TDP-43 activity, such as increased DNA damage and activation of cryptic exon splicing. We find that aggregate seeding also induces cryptic exon splicing in human neurons implying that this pathological link extends to disease-relevant models. The seeding model provides a platform for dissecting mechanisms that underlie TDP-43 pathology and for identifying factors that modulate the aggregation-to-dysfunction transition. Our data shows that aggregate seeding impacts TDP-43 autoregulation, initiating a toxic feed-forward mechanism that disrupts TDP-43 homeostasis. Furthermore, reducing ataxin-2 levels decreases aggregation and restores TDP-43 activity. Together, these findings reveal a molecularly guided strategy to directly impact TDP-43 activity by decreasing its misfolding and aggregation, highlighting approaches to prevent TDP-43 dysfunction and mitigate toxicity under pathological conditions.

ID: 42015737
Title: Glutaredoxin-1 attenuates transactive response DNA-binding protein 43-induced neurotoxicity by suppressing oxidative stress and transactive response DNA-binding protein 43 aggregation.
Abstract: Cytoplasmic aggregation of transactive response DNA-binding protein 43 (TDP-43) represents pathological hallmarks of TDP-43 proteinopathies. Accumulating evidence indicates that oxidative stress plays a pivotal role in these disorders by promoting TDP-43 aggregation and subsequent neurotoxicity. Glutaredoxin-1 (Grx1) is a key antioxidant enzyme that maintains cellular redox homeostasis. In this study, we investigated the role of Grx1 in TDP-43 proteinopathy. We examined the effects of Grx1 in neuro-2a cells expressing human wild-type TDP-43 (N2a-hTDP-43), a cellular model of TDP-43 proteinopathy characterized by increased oxidative stress, TDP-43 aggregation, and neurotoxicity. In N2a-hTDP-43 cells, Grx1 expression was increased in parallel with elevated oxidative stress. Increasing Grx1 significantly suppresses intracellular oxidative stress and cytoplasmic TDP-43 aggregation in N2a-hTDP-43 cells. Notably, increasing Grx1 significantly reduces cleaved caspase-3 levels in N2a-hTDP-43 cells, indicating reduced neurotoxicity. Collectively, our findings demonstrate that Grx1 attenuates neurotoxicity by suppressing oxidative stress and TDP-43 aggregation, highlighting its potential as a therapeutic target for TDP-43 proteinopathies.

ID: 42051315
Title: Statins and genetic inhibition of the mevalonate pathway activate an ATF3-STMN2 regenerative program.
Abstract: Loss of neuronal regenerative capacity is a common feature of neurodegenerative disease and axonal injury, yet the transcriptional programs governing this state remain poorly defined. Stathmin-2 (STMN2), a tubulin-binding protein essential for axon maintenance and repair, is profoundly depleted following loss of nuclear TDP-43 in neurodegenerative disease. Here, we identify statins as potent inducers of STMN2 expression. Pharmacological and genetic suppression of the mevalonate pathway, and subsequent prevention of protein geranylgeranylation, restored STMN2 levels in TDP-43 deficient cells and promoted neurite growth. STMN2 induction was abrogated when using a statin analogue unable to interact with HMG-CoA reductase, and through co-administration of mevalonate or geranylgeranyl diphosphate substrates. RNA-seq revealed that statins induce a coordinated pro-regenerative transcriptional response, including activation of the AP-1 transcription factor complex gene, ATF3. Loss of ATF3 attenuated STMN2 induction in vitro, and diminished injury-induced Stmn2 upregulation in spinal motor neurons in vivo. These results demonstrate statins as modulators of ATF3 and STMN2 expression and highlight their therapeutic potential in neurodegenerative disease.

ID: 42171508
Title: Kinetics and Spatial Distribution of β-Sheet Development in TDP-43CTD Condensate Maturation.
Abstract: Cytosolic inclusions of aggregated TAR DNA-binding protein 43 (TDP-43) are hallmarks of neurodegenerative disorders such as amyotrophic lateral sclerosis and frontotemporal lobar dementia. A prevailing hypothesis suggests that TDP-43 condensates undergo a liquid-to-solid transition during maturation, involving the formation of β-sheet-rich, amyloid-like aggregates. To test this hypothesis, we sought to study the temporal and spatial evolution of protein secondary structure within individual condensates by Raman spectroscopy. We measured in vitro β-sheet development of the C-terminal domain of TDP-43 (TDP-43CTD) at the single-condensate level under physiological solution conditions. All condensates showed apparent single-exponential kinetics (k = 1.6 × 10-5 s-1) for the disordered-to-β-sheet transformation, as indicated by increased amide-I intensity and a shift of the amide-III band to lower energy. Interestingly, the water bend-libration band exhibited a slower rate (k = 4.0 × 10-6 s-1), suggesting that changes in the water environment lag behind protein conformational rearrangement. Further, Raman maps revealed that protein density is highest near the condensate center, whereas β-sheet content is mostly uniform in the interior of the condensate. The unexpected difference between the spatial distributions of β-sheet content and protein density challenges the typical concentration-dependent model of protein aggregation. Importantly, rare events were captured where condensates exhibited spatially asymmetric β-sheet development, revealing localized structural heterogeneity not detectable by ensemble measurements. Collectively, these results provide insight into the temporal and spatial dynamics of protein structure within TDP-43CTD condensates and demonstrate the utility of Raman spectral imaging for tracking condensate maturation.

ID: 42178983
Title: Protein Disulfide Isomerase Disassembles TDP-43/G3BP1 Condensates and Antagonizes TDP-43 Pathological Aggregates.
Abstract: Cytoplasmic mislocalization and aggregation of transactive response DNA-binding protein-43 (TDP-43) is a common pathological feature of amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration, and Alzheimer's disease with TDP-43 pathology (AD-TDP); the exact role of protein disulfide isomerase (PDI), an enzyme with chaperone activity, in modulating the pathological behavior of TDP-43 is unknown. In this study, we report that wild-type PDI, through its specific interaction with TDP-43, markedly attenuates phase separation of TDP-43, competitively displaces G3BP1 to disassemble TDP-43/G3BP1 condensates, and further counteracts the pathological mislocalization, abnormal phosphorylation, and pathological aggregation of TDP-43 through the b' domain of the enzyme. Ultimately, this alleviates mitochondrial damage and neuronal toxicity caused by TDP-43 aggregation and suppresses UNC13A cryptic splicing in stressed cells. In the presence of abnormal forms of PDI, however, PDI loses its activity, and stress granules containing TDP-43 are assembled into amyloid fibrils, resulting in mitochondrial impairment and neuronal cell death in ALS and AD-TDP patients. These findings not only provide new insights into the pathogenic mechanisms of TDP-43 in neurodegenerative diseases such as ALS and AD-TDP, but also propose PDI as a potential therapeutic target.

ID: 42206050
Title: AI-driven insights into protein misfolding and innate immunity in neurodegenerative diseases.
Abstract: Neurodegenerative diseases encompass a diverse group of disorders ranging from adult-onset conditions such as Alzheimer's and Parkinson's disease to pediatric forms including neuronal ceroid lipofuscinoses (NCLs), Niemann-Pick type C (NPC), and infantile neuroaxonal dystrophy (INAD), all of which are characterized by protein misfolding and chronic neuroinflammation. During their occurrence and development, the innate immune system, especially the immune responses mediated by microglia in the central nervous system, plays a crucial regulatory role. Increasing evidence indicates that misfolded and abnormally aggregated proteins, such as β-amyloid (Aβ), Tau, α-synuclein, and TDP-43, are not only neurotoxic factors but can also act as damage-associated molecular patterns (DAMPs) recognized by innate immune receptors, thereby triggering persistent neuroinflammatory responses. However, traditional experimental and computational methods still have significant limitations in systematically analyzing the "protein misfolding-innate immune activation" mechanism. In recent years, artificial intelligence has made breakthrough progress in protein structure prediction, multi-conformation modeling, and integration of multi-omics data, providing a new research paradigm for revealing the intrinsic relationship between protein misfolding and innate immunity across the spectrum of neurodegenerative diseases. This article systematically reviews the latest applications of artificial intelligence in predicting the conformational characteristics of misfolded proteins, simulating the protein aggregation process, revealing the mechanism of innate immune perception, and reconstructing the regulatory network of neuroinflammation. It focuses on discussing the significance of deep learning models such as AlphaFold, I-TASSER, RoseTTAFold, Phyre2, and ESMFold in the field of protein structure prediction, as well as the related research on multi-modal AI technology in revealing the complex molecular mechanisms behind neurodegenerative diseases, such as combining AI with mathematical models to simulate the spread of misfolded proteins and further exploring the association with disease progression. The review also highlights the potential of AI to address the diagnostic challenges unique to pediatric neurodegenerative disorders, which, despite their rarity, collectively impose devastating lifelong burdens. In summary, AI tools not only deepen our understanding of the molecular mechanisms underlying both adult and childhood neurodegenerative diseases but also open up new avenues for developing innovative diagnostic tools and treatment methods.

ID: 42219390
Title: A Conjugate of Aminoadamantane and Tetrahydro-γ-Carboline Inhibits Accumulation of Mutant α-Synuclein A53T in the Cellular Model of Proteinopathy.
Abstract: Pathological aggregation of α-synuclein is a key event in the development of synucleinopathies, such as Parkinson's disease and Lewy body dementia. Currently, no effective disease-modifying therapy is available, necessitating the search for new therapeutic agents. One promising strategy involves the use of low-molecular-weight compounds capable of inhibiting the formation of toxic protein aggregates. This study evaluates the anti-aggregation properties of EC3222x, a conjugate of pharmacophoric fragments of amantadine and a fluorinated derivative of tetrahydro-γ-carboline. α-Synucleinopathy was modeled in the SH-SY5Y neuroblastoma cell line by transfection with a plasmid vector encoding the mutant human α-synuclein A53T protein. EC3222x at a concentration of 1 µM reduced the number of cells with α-synuclein A53T aggregates. Its efficacy was comparable to that of SynuClean-D and Buntanetap, known inhibitors of α-synuclein aggregation. Treatment with EC3222x reduced both the level of diffusely distributed intracellular α-synuclein and the formation of mature fibrillar aggregates and large aggresomes. Importantly, EC3222x did not affect the accumulation of another aggregation-prone protein, TDP-43, in a similar cellular model, indicating its specificity for α-synuclein. These findings suggest that EC3222x may represent a promising candidate for the development of therapeutic agents targeting synucleinopathies.

ID: 42239172
Title: The retroelement-derived human protein PEG10 is a regulator of mRNA splicing in neurons.
Abstract: Retroelements, including retrotransposons, endogenous retroviruses, and their fragments, as well as rare co-opted or domesticated retroelements, can contribute to neurodegenerative disorders and aging through modulation of gene expression and induction of neuroinflammation. Paternally Expressed Gene 10 (PEG10) is a retroelement-derived human gene that has recently been identified as a putative driver of Amyotrophic Lateral Sclerosis (ALS) and Angelman's Syndrome. PEG10 has been reported to bind nucleic acid and undergoes a complex self-processing pathway that results in gene expression changes when the protein accumulates in cells. Here, we report that PEG10 has selectivity for binding U/G-rich RNAs and influences widespread gene expression changes. PEG10 overexpression mimics the loss of TDP-43 in broad changes to gene expression, including dysregulation of mRNA splicing pathways. Specific changes to mRNA splicing were largely unique between TDP-43 knockdown and PEG10 overexpression, as classic TDP-43 targets including STMN2 were not altered by PEG10. Instead, we identified a unique role for PEG10 in regulating splicing of neuregulin 3 (NRG3), a ligand for the neuronal receptor ERBB4. In SH-SY5Y cells and in human neurons overexpressing PEG10, NRG3 protein levels were decreased along cellular processes, suggesting that these cells are less competent at signaling through the NRG3/ERBB4 axis. Using human patient data, we observed similar changes to NRG3 splicing in UBQLN2-mediated ALS, where PEG10 is accumulated, as well as in some cases of sporadic ALS. In conclusion, the retroelement-derived gene PEG10 plays an unexpected role in regulating splicing of neuronal transcripts, which mimics some of the transcript changes observed in human ALS patient samples. Ultimately, this work has implications for the study of PEG10, and mRNA splicing in neurological diseases associated with elevated PEG10 abundance.

ID: 42244557
Title: Thalamus-derived glutamate is required for early specification of layer 4 neurons in the sensory cortex.
Abstract: Elucidating the mechanisms that control the formation of the mammalian neocortex is crucial for understanding brain functions. Synaptic activity of thalamocortical axons (TCAs), mediated by glutamate, exerts a major extrinsic influence on the maturation of their target layer 4 neurons in postnatal primary sensory cortex. However, TCAs reach the sensory cortex during mid-embryonic stages in mice, when neurons of future superficial layers, including layer 4, are still being generated from radial glia (RGs) or intermediate progenitor cells (IPCs), well before the formation of direct synapses. We previously showed that TCAs are required for the production and specification of the proper number of layer 4 neurons in sensory areas, and that part of these area-specific roles is played by the thalamus-derived molecule VGF. However, the role of TCA-derived glutamate prior to synapse formation has remained unclear. In this study, we used mutant mice lacking vGluT2 , a vesicular glutamate transporter expressed in the embryonic thalamus, and found that vesicular release of thalamus-derived glutamate is required for the proper production and specification of layer 4 neurons in the sensory cortex by the neonatal stage, through mechanism distinct from those involving VGF. Our findings reveal that multiple molecular cues produced by incoming TCAs play distinct roles in the production and specification of layer 4 neurons in the sensory cortex.

ID: 42276614
Title: Glutamate and glutamine metabolism in neurodegenerative diseases.
Abstract: Glutamate is known as the most important excitatory neurotransmitter in brain. Glutamate and glutamine recycling is very essential to maintain the nitrogen metabolism. Despite of its major functions, its dysregulation is a basic pathology which is common to neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), and Amyotrophic lateral sclerosis (ALS). Amyloid-β and Tau in AD disrupt glutamate uptake and the glutamate-glutamine cycle, accelerating synaptic failure, whereas loss of astrocytic EAAT2 in ALS generates unrelenting excitotoxicity and motor neuron demise. Toxic α-synuclein aggregation in PD exacerbates dopamine-glutamate imbalance through destabilizing corticostriatal transmission. This review explores on the key mechanisms by which glutamate impairment leads to the pathogenies of neurogenerative disorders and also about current medications like amantadine, memantine, and riluzole which are glutamate antagonists, are shown to partially alleviative but cannot halt the advancement of the disease. One of the potential targets for disease-modifying treatments could be the receptor modulation, astrocytic function, and elimination of excess glutamate.

ID: 42323448
Title: Single-cell reconstruction of whole-brain efferent projections from mouse ventral posteromedial thalamus.
Abstract: The ventral posteromedial thalamic nucleus (VPM) relays orofacial somatosensory signals to the primary somatosensory cortex (SSp), yet its functional heterogeneity remains poorly defined at single-cell resolution. We combined fluorescence micro-optical sectioning tomography (fMOST) with single-neuron whole-brain reconstruction to map projections of vesicular glutamate transporter 2-positive (VGluT2⁺) excitatory neurons in the ventrolateral subdivision of VPM (vlVPM). Using 88 high-quality neurons with validated completeness, we identified pronounced structural heterogeneity and classified two clusters with distinct axonal profiles. Notably, we report two key findings that challenge the classical view: vlVPM neurons preferentially target superficial SSp layers (L1-3) rather than layer 4 (L4), and a multi-target subpopulation simultaneously innervates the motor cortex and basal ganglia via collaterals, establishing direct anatomical links to motor regulatory networks. These anatomical findings demonstrate that vlVPM establishes diverse projection pathways beyond canonical sensory relays, enabling direct structural crosstalk between sensory and motor circuits. This work provides a single-cell resolution framework for interpreting the anatomical basis of thalamic involvement in sensorimotor coordination.

ID: 42324254
Title: Direct evidence of upper motor neuron excitability changes in a patient with ALS.
Abstract: A key feature of amyotrophic lateral sclerosis (ALS) pathophysiology is motor neuron hyperexcitability. However, the mechanisms of hyperexcitability are not well understood. Prior studies have used transcranial magnetic stimulation (TMS) to demonstrate increased motor cortex excitability and reduced intracortical inhibition in human ALS. Yet, interpretation of these findings is limited because measurement of muscle responses cannot disentangle the specific contribution of upper and lower motor neurons and of cortical interneurons to excitability changes. We had the rare opportunity to record directly the corticospinal output evoked by TMS upstream of the spinal circuitry in a patient with ALS who had undergone epidural electrode implantation for intractable pain. Single-pulse stimulation was performed both with a coil orientation inducing a current that activates corticospinal neurons directly, and with a coil orientation inducing a current that activates corticospinal neurons trans-synaptically. Short-interval intracortical inhibition (SICI) was also studied using paired-pulse stimulation. Data obtained from the patient were compared with those recorded in 10 conscious control subjects. Compared with control subjects, patient showed a reduced amplitude in response to direct corticospinal neuron activation, yet an enhanced amplitude of corticospinal output after trans-synaptic corticospinal neuron activation, together with a SICI reduction. Present findings provide direct evidence of hyperexcitability of monosynaptic glutamatergic inputs to corticospinal neurons that, in association with reduced intracortical inhibition, can trigger neurodegeneration. Taken together with the extensive body of evidence generated by noninvasive TMS studies, the findings from this single-case study may provide valuable insights into the pathophysiological mechanisms of the disease.NEW & NOTEWORTHY The response evoked by direct activation of corticospinal neurons is reduced in human amyotrophic lateral sclerosis (ALS). In contrast, the response evoked by trans-synaptic activation of these cells is enhanced. The activity of inhibitory inputs to corticospinal neurons is reduced. These abnormalities related to abnormal excitatory and inhibitory input processing by corticospinal neurons may trigger neurodegeneration.

ID: 42340705
Title: Neurometabolites and Antipsychotic Response in Psychosis: A Mega-Analysis.
Abstract: Revealing neurobiological markers of antipsychotic nonresponse in psychosis may aid outcome prediction and inform novel treatment targets. To examine differences in neurometabolites in antipsychotic nonresponsive compared to antipsychotic-responsive psychosis using individual participant data and meta-analysis. Web of Science was searched for studies published between January 1, 1980, and November 1, 2025. Authors of 21 eligible studies identified before August 2024 were invited to contribute individual participant data. Eighteen studies examining neurometabolites by treatment response in psychosis contributed individual participant data for the mega-analysis. These studies plus a further 5 studies were included in the meta-analyses of standardized mean differences and variability. Individual participant data were analyzed using linear mixed models with study as a random effect. Subgroup analyses examined prospective designs and treatment-resistant samples. Published group means and standard deviations were extracted for meta-analyses. Group differences in glutamate, glutamate plus glutamine, choline, myo-inositol, N-acetylaspartate, γ-aminobutyric acid, and glutathione in the medial frontal cortex, dorsolateral prefrontal cortex, thalamus, and basal ganglia. The mega-analysis included 1189 participants from 18 studies; of these, 476 were treatment nonresponders (mean [SD] age, 33.0 [12.5] years; 340 male), 427 were treatment responders (mean [SD] age, 30.3 [11.5] years; 299 male), and 286 were healthy control individuals (mean [SD] age, 31.0 [12.5] years; 170 male). Compared with the antipsychotic response group, nonresponders showed elevations in medial frontal glutamate (Glass Δ = 0.21; P = .02), glutamate plus glutamine (Glass Δ = 0.29; P = .002), choline (Glass Δ = 0.22; P = .03), and myo-inositol (Glass Δ = 0.35; P = .001); similar elevations were observed relative to control individuals. Elevated medial frontal glutamate plus glutamine in antipsychotic nonresponders compared with responders was also observed prospectively in first-episode psychosis (Glass Δ = 0.41; P = .002), whereas myo-inositol elevations were greatest in individuals meeting criteria for treatment-resistance (Glass Δ = 0.64; P = .001). The meta-analysis of 23 studies (1844 participants) also showed elevated medial frontal choline and myo-inositol in antipsychotic nonresponse compared with response. These findings provide evidence of an association between antipsychotic nonresponse in psychosis with elevations in medial frontal glutamate, choline, and myo-inositol. The presence of elevations in these markers supports the continued investigation of glutamate-acting and inflammatory pathway-associated interventions for psychosis and schizophrenia.

ID: 42343570
Title: STMN2 protein depletion via translation deficits and stress granules in amyotrophic lateral sclerosis.
Abstract: STMN2 is an abundant neurospecific protein dysregulated in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). We previously reported that cellular stress can lead to STMN2 loss due to TDP-43 nuclear condensation. Here, using human and murine neuronal cell models, multiple pharmacological tools, in situ single-molecule analysis of translation and RNA localisation, and longitudinal analysis of neuronal fitness/survival, we establish TDP-43-independent mechanisms of STMN2 depletion under stress. We find that human STMN2 protein level is extremely labile under acute high-magnitude stress. Early in stress, STMN2 is suppressed via activated proteasomal degradation, phosphorylation and translation repression by stress granules, independently of TDP-43 loss of function in splicing. We further show that STMN2 protein level is highly sensitive to chronic translation deficits, such as those elicited by prolonged low-grade stress. We find that low pre-stress STMN2 sensitises neuronal cells to stress-induced apoptosis, whereas moderately increased STMN2 is protective under stress. Finally, we demonstrate that STMN2 mRNA is upregulated in non-TDP ALS (ALS-FUS) models, which may compensate for translation/stress granule defects in this disease subtype. Consistent with the compensation hypothesis, STMN2 mRNA is also upregulated in the relatively spared (cortex), but not severely affected (spinal cord), CNS regions in ALS-TDP. In conclusion, our study implicates two common denominators in neurodegeneration - dysregulation of translation and stress granules - in STMN2 depletion, independent of TDP-43 loss of function. It also describes an RNA-based compensatory mechanism in ALS underling the unique vulnerability of neurons with developing TDP-43 pathology.

ID: 42365211
Title: A new paradigm in Parkinson's disease: kidney-origin α-synuclein pathology driven by PKC signaling and aurothioglucose.
Abstract: Protein Kinase C (PKC), a zinc-dependent signaling enzyme essential for cellular homeostasis, has recently emerged as a critical regulator of α-synuclein (α-Syn) dynamics beyond the central nervous system. Growing evidence suggests that PKC may contribute to α-Syn accumulation in kidney cells through multiple converging mechanisms, including direct phosphorylation of α-Syn, which promotes its aggregation, disruption of the autophagy-lysosome pathway leading to impaired protein clearance, and amplification of oxidative stress and inflammatory responses that enhance α-Syn toxicity. In a paradigm-shifting discovery, recent findings from Wuhan University indicate that Parkinson's disease (PD) pathology may originate in peripheral organs such as the kidneys rather than the brain. Abnormal α-Syn aggregates have been identified in renal tissues of affected individuals, and experimental models demonstrate that compromised kidney function facilitates the systemic spread of these toxic proteins to the brain, potentially initiating neurodegeneration. Notably, α-Syn accumulation has also been observed in patients with chronic kidney disease in the absence of neurological symptoms, suggesting a potential early reservoir function of the kidneys. In this context, aurothioglucose (ATG), a gold-based anti-inflammatory agent, emerges as a promising therapeutic candidate due to its ability to modulate PKC signaling, attenuate inflammation, and restore proteostatic balance. This review highlights a novel kidney-brain axis in PD pathogenesis and proposes PKC-targeted interventions, including ATG, as potential strategies for early disease modification.

ID: 42365390
Title: Lysophagy protects against ANXA11 amyloid fibril toxicity and propagation in FTLD.
Abstract: Accumulation of Annexin A11 (ANXA11) aggregates is a distinct pathological hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). While genetic studies have linked ANXA11 mutations (e.g., D40G) to disease, the precise molecular events converting aggregation into neurotoxicity and intercellular propagation remain elusive. We hypothesize that lysosomal integrity serves as a critical checkpoint in ANXA11 proteinopathy and that its failure drives disease progression. To model the human pathology of ANXA11, we generated pre-formed fibrils (PFFs) of wild-type and FTLD/ALS-linked D40G mutant ANXA11. Human iPSC-derived neurons, 3D cerebral organoids, and bulk RNA-sequencing were employed to investigate neurotoxicity. High-resolution imaging, lentiviral knockdown, and biochemical assays were performed to delineate the lysosomal damage response and the subsequent "prion-like" spreading of aggregates. The internalized ANXA11 fibrils accumulated in lysosomes, triggering lysosomal membrane permeabilization (LMP). The D40G mutation exacerbated this toxicity, leading to severe LMP, mitochondrial depolarization, and specific transcriptional downregulation of the dynactin subunit ACTR10. Mechanistically, we identified a protective signaling axis involving p38 MAPK, MK2, and HSP27 that senses ANXA11-induced lysosomal damage and initiates lysophagy. Notably, in human cerebral organoids, failure of this lysophagic clearance facilitated the cytoplasmic escape of ANXA11, thereby accelerating its seeding activity and propagation to neighboring cells. Pharmacological or genetic modulation of this pathway significantly altered neuronal survival. Our study established lysosomal rupture as a primary driver of ANXA11-associated neurodegeneration and validated the p38/MK2/HSP27 axis as a crucial defense mechanism in human neural tissue. These findings provide a novel mechanistic link between lysosomal quality control and ANXA11 propagation, highlighting that enhancing lysophagic flux represents a promising translational strategy to halt the progression of FTLD and ALS.

ID: 42386071
Title: Amylin at the crossroads of type 2 diabetes and neurodegenerative diseases.
Abstract: Type 2 diabetes (T2D) is traditionally viewed as a metabolic disease centered on insulin resistance and β-cell failure. However, growing evidence supports its reclassification as a systemic proteinopathy, in which the aggregation of amylin (islet amyloid polypeptide, IAPP) emerges as a key pathogenic event. In this review, we examine the shift toward an IAPP-centric model of disease, highlighting how IAPP misfolding and aggregation drive β-cell dysfunction independently of, and in parallel with, metabolic stress. We integrate recent advances in the structural biology of IAPP to provide a mechanistic framework for its cytotoxicity. IAPP aggregation disrupts cellular homeostasis through membrane damage, proteostasis imbalance, mitochondrial dysfunction, oxidative and ER stress, and inflammation, ultimately leading to progressive β-cell loss. Beyond the pancreas, we position IAPP as a molecular bridge between peripheral metabolic stress and neurodegeneration. Through prion-like cross-seeding, IAPP interacts with Aβ, tau, α-synuclein, and PrP, linking T2D as a major risk factor for neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. We review emerging therapeutic strategies, including long-acting non-fibrillating analogues that suppress endogenous secretion, cross-amyloid inhibitors, conformation-specific immunotherapies, and synthetic chaperones. Finally, we discuss structure-based and AI-driven diffusion models as tools to design binders that selectively mask the amyloidogenic core while preserving the homeostatic function of IAPP. Given the projected magnitude of T2D, targeting the IAPP-neurodegeneration axis through early detection and midlife intervention is essential to mitigating the impending socioeconomic impact of combined metabolic and cognitive decline.