The Fragile X Messenger Ribonucleoprotein (FMRP) is a selective RNA-binding protein that localizes to the cytoplasm and the nucleus. The loss of FMRP results in Fragile X Syndrome (FXS), an autism spectrum disorder. FMRP interacts with ribosomes and regulates the translation of mRNAs essential for neuronal development and synaptic plasticity. However, the biochemical nature of this translation regulation is unknown. Here, we report that a potential feature of FMRP-mediated translation regulation during neuronal differentiation is the modulation of 2'-O-methylation of ribosomal RNA. 2'O-methylation, facilitated by C/D box snoRNAs in the nucleus, is a major epitranscriptome mark on rRNA, essential for ribosome assembly and function. We found that FMRP influences a distinct rRNA 2'O-Methylation pattern across neuronal differentiation. We show that in H9 ESCs, FMRP interacts with a selected set of C/D box snoRNA in the nucleus, resulting in the generation of ribosomes with a distinct pattern of rRNA 2'O-Methylation. This epitranscriptome pattern on rRNA undergoes a significant change during the differentiation of ESCs to neuronal precursors and cortical neurons. ESCs exhibit substantial levels of hypomethylated residues on rRNA, which progressively decrease in neuronal precursors and post-mitotic cortical neurons. This reduction correlates with changes in global protein synthesis across different stages of differentiation. Importantly, this stepwise change in the 2'O-methylation pattern during neuronal differentiation is altered in the absence of FMRP, which could impact neuronal development and contribute to dysregulated protein synthesis observed in Fragile X Syndrome.

Epitranscriptomic modification of RNA is an important layer of regulation for gene expression. RNA modifications come in many flavors and generate a complex tapestry of a regulatory network. Here, we focus on two major RNA modifications, one on rRNA (2'O Methylation) and another on mRNA (N6-Methyladenosine [m6A]) and their impact on translation. The 2'O methyl group addition on the ribose sugar of rRNA plays a critical role in RNA folding, ribosome assembly, and its interaction with many RNA binding proteins. Differential methylation of these sites contributes to ribosome heterogeneity and generates potential "specialized ribosomes." Specialized ribosomes are proposed to play a variety of important roles in maintaining pluripotency, lineage specification, and compartmentalized and activity-mediated translation in neurons. The m6A modification, on the other hand, determines the stability, transport, and translation of subclasses of mRNA. The dynamic nature of m6A owing to the localization and activity of its writers, readers, and erasers makes it a powerful tool for spatiotemporal regulation of translation. While substantial information has accumulated on the nature and abundance of these modifications, their functional consequences are still understudied. In this article, we review the literature constructing the body of our understanding of these two modifications and their outcome on the regulation of translation in general and their impact on the nervous system in particular. We also explore the possibility of how these modifications may collaborate in modulating translation and provoke the thought to integrate the functions of multiple epitranscriptome modifications.

Astroglia play crucial neuroprotective roles by internalizing pathogenic aggregates and facilitating their degradation. Here, we show that α-SYN protofibril-induced organelle toxicities and reactive oxygen species (ROS) cause premature cellular senescence in astrocytes and astrocyte-derived cancer cells, resulting in a transient increase in the biogenesis of tunneling nanotubes (TNTs). TNT-biogenesis and TNT-mediated cell-to-cell transfer lead to clearance of α-SYN-induced organelle toxicities, reduction in cellular ROS levels, and reversal of cellular senescence. Enhanced cell proliferation is seen in the post-recovered cells after recovering from α-SYN-induced organelle toxicities. Further, we show that α-SYN-induced senescence promotes the transient localization of focal adhesion kinase (FAK) in the nucleus. FAK-mediated regulation of Rho-associated kinases plays a significant role in the biogenesis of TNTs and their subsequent proliferation. Our study emphasizes that TNT biogenesis has a potential role in the clearance of α-SYN-induced cellular toxicities, the consequences of which cause enhanced proliferation in the post-recovered astroglia cells.

Fragile X Messenger Ribonucleoprotein 1 (FMRP) is a multifunctional, multidomain RNA-binding protein whose loss causes Fragile X syndrome. It is also known to associate with ribosomes and modulate translation. In human embryonic stem cells (hESCs), knockout (KO) of the FMR1 gene results in significantly increased protein translation rates and alterations in the 2′-O-methylation patterns of rRNA. To understand the structural underpinnings of the process, we performed electron cryomicroscopy analysis of ribosomes isolated from both the wild-type (WT) and FMR1 KO hESCs that revealed a subpopulation of dormant ribosomes in the FMR1 KO cells, in addition to ribosomes with tRNAs. This dormant subpopulation, absent in the WT hESCs, is characterized by the binding of SERPINE-mRNA binding protein 1 in the mRNA tunnel and eukaryotic elongation factor 2 near the A-site, preventing translation. The presence of elevated protein translation in FMR1 KO cells, alongside a subpopulation of inactive ribosomes, suggests that FMRP can function as a translational brake. However, due to the high cost of ribosome recycling, the cell appears to adopt a strategy of maintaining a subset of dormant ribosomes. Additionally, we analysed the 2′-O-methylation patterns in the 28S rRNA, in both the WT and FMR1 KO hESCs, identifying few potential differentially methylated sites. Thus, these findings provide insights into the mechanisms of ribosome dormancy in the absence of FMRP and lay the groundwork for understanding the role of rRNA methylation in translational regulation. ### Competing Interest Statement The authors have declared no competing interest.

Calcium signaling is integral for neuronal activity and synaptic plasticity. We demonstrate that the calcium response generated by different sources modulates neuronal activity-mediated protein synthesis, another process essential for synaptic plasticity. Stimulation of NMDARs generates a protein synthesis response involving three phases-increased translation inhibition, followed by a decrease in translation inhibition, and increased translation activation. We show that these phases are linked to NMDAR-mediated calcium response. Calcium influx through NMDARs elicits increased translation inhibition, which is necessary for the successive phases. Calcium through L-VGCCs acts as a switch from translation inhibition to the activation phase. NMDAR-mediated translation activation requires the contribution of L-VGCCs, RyRs, and SOCE. Furthermore, we show that IP3-mediated calcium release and SOCE are essential for mGluR-mediated translation up-regulation. Finally, we signify the relevance of our findings in the context of Alzheimer's disease. Using neurons derived from human fAD iPSCs and transgenic AD mice, we demonstrate the dysregulation of NMDAR-mediated calcium and translation response. Our study highlights the complex interplay between calcium signaling and protein synthesis, and its implications in neurodegeneration.

ABSTRACT ApoE4 isoform contributes to increased risk for Alzheimer’s Disease (AD) over the life course of individuals. Much remains unknown about the biological pathways that connect APOE4 genotype with the development of pathology that eventually leads to AD, nor do we know how early in life these cellular alterations begin. To answer these questions, we derived neural precursor cells (NPCs) from induced pluripotent stem cells (IPSCs) that were CRISPR-edited at the APOE locus. We intended to characterize the protein expression landscape in the NPCs subsequent to targeted deletion of E4 from a parent IPSC line of APOE3/4 genotype. Differentially expressed proteins (DEPs) following mass spectrometric analysis were determined from the protein abundance fold change values obtained for each protein. Proteins which showed >1.5-fold difference with FDR adjusted P-value < 0.05 were considered differentially expressed. DEPs were mapped to the STRING database (v11.5) for retrieval of interacting proteins and functional enrichment. CRISPR-editing of E4 from the parent line revealed 98 differential expressed proteins. Of these, 54 were upregulated, and 44 were downregulated. Further analysis of the DEPs via STRING database showed that these changes primarily affect pathways linked to RNA processing, plasma membrane repair, and cytoskeleton organization. Indeed, we find the effects of E4 extend beyond proteins considered central to AD pathology. Knowing more about the protein interactions regulated by ApoE, in an isoform-specific manner, can reveal new mechanistic insights into development of AD.

Alzheimer’s disease (AD) is the most common cause of dementia, with no current cure. Consequently, alternative approaches focusing on early pathological events in specific neuronal populations, besides targeting the well-studied amyloid beta (Aβ) accumulations and Tau tangles, are needed. In this study, we have investigated disease phenotypes specific to glutamatergic forebrain neurons and mapped the timeline of their occurrence, by implementing familial and sporadic human induced pluripotent stem cell models as well as the 5xFAD mouse model. We recapitulated characteristic late AD phenotypes, such as increased Aβ secretion and Tau hyperphosphorylation, as well as previously well documented mitochondrial and synaptic deficits. Intriguingly, we identified Golgi fragmentation as one of the earliest AD phenotypes, indicating potential impairments in protein processing and post-translational modifications. Computational analysis of RNA sequencing data revealed differentially expressed genes involved in glycosylation and glycan patterns, whilst total glycan profiling revealed minor glycosylation differences. This indicates general robustness of glycosylation besides the observed fragmented morphology. Importantly, we identified that genetic variants in Sortilin-related receptor 1 (SORL1) associated with AD could aggravate the Golgi fragmentation and subsequent glycosylation changes. In summary, we identified Golgi fragmentation as one of the earliest disease phenotypes in AD neurons in various in vivo and in vitro complementary disease models, which can be exacerbated via additional risk variants in SORL1.

Astrocytic cells are a subtype of glial cells that engulf pathogenic aggregates derived from degenerative neurons to facilitate its degradation. Here, we show that exposure to α-SYN protofibrils caused a transient increase in biogenesis of tunneling nanotubes (TNTs) in primary astrocytes and astrocyte-origin cancer cell-lines (U-87 MG, U251). Biogenesis of nascent TNTs corresponds to α-SYN protofibril-induced organelle toxicities, increased reactive oxygen species (ROS), and oxidative stress-induced premature cellular senescence. These TNTs mediate cell-to-cell transfer of α-SYN protofibrils, toxic lysosomes and mitochondria. Biogenesis of TNTs precedes clearance of α-SYN-induced organelle toxicities, cellular ROS levels and reversal of cellular senescence. Consequences of cellular clearance results in enhanced cell proliferation. Further, we have shown α-SYN-induced senescence promotes transient localization of focal adhesion kinase (FAK) in the nucleus. FAK mediated regulation of Rho-associated kinases may have a role in the biogenesis of TNTs, successively proliferation. Our study emphasizes that TNT biogenesis may have a potential role in the clearance of α-SYN toxicities and reversal of stress-induced cellular senescence, consequences of which cause enhanced proliferation in the post-recovered astroglia cells. Highlights α-SYN protofibrils treated astroglia cells proliferate upon transient biogenesis of TNTs. Transient TNT biogenesis precedes clearance of α-SYN toxicities and reversal of senescence. Stress-induced senescence results in nuclear localization of FAK and ROCK mediated TNT biogenesis. The rescued cells enhance proliferation through ROCK mediated ERK1/2 and NFκB signalling cascades. Synopsis Graphical Abstract: α-SYN protofibrils-induced biogenesis of tunneling nanotubes (TNTs) aids to enhance cellular clearance of toxic burdens as a cellular survival strategy. α-SYN protofibrils treated toxic senescence cells regulate FAK mediated modulation of ROCK signalling cascades to promote TNT biogenesis and rescue the cellular toxicities. The rescued cells eventually enhance cell proliferation.

Intellectual disability (ID) and autism spectrum disorder (ASD) are neurodevelopmental disorders that have become a primary clinical and social concern, with a prevalence of 2-3% in the population. Neuronal function and behaviour undergo significant malleability during the critical period of development that is found to be impaired in ID/ASD. Human genome sequencing studies have revealed many genetic variations associated with ASD/ID that are further verified by many approaches, including many mouse and other models. These models have facilitated the identification of fundamental mechanisms underlying the pathogenesis of ASD/ID, and several studies have proposed converging molecular pathways in ASD/ID. However, linking the mechanisms of the pathogenic genes and their molecular characteristics that lead to ID/ASD has progressed slowly, hampering the development of potential therapeutic strategies. This review discusses the possibility of recognising the common molecular causes for most ASD/ID based on studies from the available models that may enable a better therapeutic strategy to treat ID/ASD. We also reviewed the potential biomarkers to detect ASD/ID at early stages that may aid in diagnosis and initiating medical treatment, the concerns with drug failure in clinical trials, and developing therapeutic strategies that can be applied beyond a particular mutation associated with ASD/ID.

Epitranscriptome modifications are crucial in translation regulation and essential for maintaining cellular homeostasis. N6 methyladenosine (m6A) is one of the most abundant and well-conserved epitranscriptome modifications, which is known to play a pivotal role in diverse aspects of neuronal functions. However, the role of m6A modifications with respect to activity-mediated translation regulation and synaptic plasticity has not been studied. Here, we investigated the role of m6A modification in response to NMDAR stimulation. We have consistently observed that 5 min NMDAR stimulation causes an increase in eEF2 phosphorylation. Correspondingly, NMDAR stimulation caused a significant increase in the m6A signal at 5 min time point, correlating with the global translation inhibition. The NMDAR induced increase in the m6A signal is accompanied by the redistribution of the m6A marked RNAs from translating to the non-translating pool of ribosomes. The increased m6A levels are well correlated with the reduced FTO levels observed on NMDAR stimulation. Additionally, we show that inhibition of FTO prevents NMDAR mediated changes in m6A levels. Overall, our results establish RNA-based molecular readout which corelates with the NMDAR-dependent translation regulation which helps in understanding changes in protein synthesis.

The Fragile-X Mental Retardation Protein (FMRP) is an RNA binding protein that regulates translation of mRNAs essential for synaptic development and plasticity. FMRP interacts with a specific set of mRNAs, aids in their microtubule-dependent transport and regulates their translation through its association with ribosomes. However, the biochemical role of FMRP’s domains in forming neuronal granules and associating with microtubules and ribosomes is currently undefined. We report that the C-terminus domain of FMRP is sufficient to bind to ribosomes akin to the full-length protein. Furthermore, the C-terminus domain alone is essential and responsible for FMRP-mediated neuronal translation repression. However, dendritic distribution of FMRP and its microtubule association is favored by the synergistic combination of FMRP domains rather than individual domains. Interestingly, we show that the phosphorylation of hFMRP at Serine-500 is important in modulating the dynamics of translation by controlling ribosome association. This is a fundamental mechanism governing the size and number of FMRP puncta that contain actively translating ribosomes. Finally through the use of pathogenic mutations, we emphasize the hierarchical contribution of FMRP’s domains in translation regulation.

It is increasingly becoming evident that ApoE4 isoform contributes to AD risk over the life course of individuals. Much remains unknown about the biological pathways that connect APOE4 genotype with the development of pathology that eventually leads to AD, nor do we know how early in life these cellular alterations begin. To answer these questions, we derived neural precursor cells (NPCs) from induced pluripotent stem cells (IPSCs) that were CRISPR‐edited at APOE locus (Ramakrishna et al. 2021; Schmid et al. 2019). We intended to characterize the protein expression landscape in the NPCs subsequent to targeted deletion of E4 from a parent IPSC line of APOE3/4 genotype.

Stress response pathways protect the lung from the damaging effects of environmental toxicants. Here we investigate the role of the fragile X mental retardation protein (FMRP), a multifunctional protein implicated in stress responses, in the lung. We report that FMRP is expressed in murine and human lungs, in the airways and more broadly. Analysis of airway stress responses in mice and in a murine cell line ex vivo, using the well-established naphthalene injury model, reveals that FMRP-deficient cells exhibit increased expression of markers of oxidative and genotoxic stress and increased cell death. Further inquiry shows that FMRP-deficient cells fail to actuate the integrated stress response pathway (ISR) and upregulate the transcription factor ATF4. Knockdown of ATF4 expression phenocopies the loss of FMRP. We extend our analysis of the role of FMRP to human bronchial BEAS-2B cells, using a 9,10-phenanthrenequinone air pollutant model, to find that FMRP-deficient BEAS-2B cells also fail to actuate the ISR and exhibit greater susceptibility. Taken together, our data suggest that FMRP has a conserved role in protecting the airways by facilitating the ISR. This article has an associated First Person interview with the first author of the paper.

Apolipoprotein E (APOE), one of the primary lipoproteins in the brain has three isoforms in humans, APOE2, APOE3, and APOE4. APOE4 is the most well-established risk factor increasing the predisposition for Alzheimer's disease (AD). The presence of the APOE4 allele alone is shown to cause synaptic defects in neurons and recent studies have identified multiple pathways directly influenced by APOE4. However, the mechanisms underlying APOE4-induced synaptic dysfunction remain elusive. Here, we report that the acute exposure of primary cortical neurons or synaptoneurosomes to APOE4 leads to a significant decrease in global protein synthesis. Primary cortical neurons were derived from male and female embryos of Sprague Dawley (SD) rats or C57BL/6J mice. Synaptoneurosomes were prepared from P30 male SD rats. APOE4 treatment also abrogates the NMDA-mediated translation response indicating an alteration of synaptic signaling. Importantly, we demonstrate that both APOE3 and APOE4 generate a distinct translation response which is closely linked to their respective calcium signature. Acute exposure of neurons to APOE3 causes a short burst of calcium through NMDA receptors (NMDARs) leading to an initial decrease in protein synthesis which quickly recovers. Contrarily, APOE4 leads to a sustained increase in calcium levels by activating both NMDARs and L-type voltage-gated calcium channels (L-VGCCs), thereby causing sustained translation inhibition through eukaryotic translation elongation factor 2 (eEF2) phosphorylation, which in turn disrupts the NMDAR response. Thus, we show that APOE4 affects basal and activity-mediated protein synthesis responses in neurons by affecting calcium homeostasis. SIGNIFICANCE STATEMENT Defective protein synthesis has been shown as an early defect in familial Alzheimer's disease (AD). However, this has not been studied in the context of sporadic AD, which constitutes the majority of cases. In our study, we show that Apolipoprotein E4 (APOE4), the predominant risk factor for AD, inhibits global protein synthesis in neurons. APOE4 also affects NMDA activity-mediated protein synthesis response, thus inhibiting synaptic translation. We also show that the defective protein synthesis mediated by APOE4 is closely linked to the perturbation of calcium homeostasis caused by APOE4 in neurons. Thus, we propose the dysregulation of protein synthesis as one of the possible molecular mechanisms to explain APOE4-mediated synaptic and cognitive defects. Hence, the study not only suggests an explanation for the APOE4-mediated predisposition to AD, it also bridges the gap in understanding APOE4-mediated pathology.

Haploinsufficiency in SYNGAP1 is implicated in Intellectual Disability (ID) and Autism Spectrum disorder (ASD) and affects the maturation of dendritic spines. The abnormal spine development has been suggested to cause disbalance of excitatory and inhibitory (E/I) neurotransmission at distinct developmental periods. In addition, E/I imbalances in Syngap1 +/- mice might be due to abnormalities in K + -Cl - co-transporter function (NKCC1, KCC2), in a similar manner as in the murine models of Fragile-X and Rett syndromes. To study whether an altered intracellular chloride ion concentration represents an underlying mechanism of altered function of GABAergic synapses in Dentate Gyrus Granule Cells of Syngap1 +/- recordings were performed at different developmental stages of the mice. We observed that neurons at P14-15 of Syngap1 +/- mice had depolarised membrane potential and a decreased Cl - reversal potential. The KCC2 expression was decreased compared to Wild-type (WT) mice at P14-15. Furtherly, the small molecule GSK-3β inhibitor, 6-bromoindirubin-3`-oxime (6BIO), was tested in an attempt to restore the function of GABAergic synapses. We discovered that intraperitoneal administration of 6BIO during the critical period or young adolescents normalized an altered E/I balance, the deficits of synaptic transmission, and behavioral performance like social novelty, anxiety, and memory of the Syngap1 +/- mice. In summary, altered functionality of GABAergic synapses in Syngap1 +/- mice is based on a reduced KCC2 expression and a subsequent increase in the intracellular chloride concentration that can be counteracted by the small molecule 6BIO. The 6BIO sufficiently restored cognitive, emotional, and social symptoms by pharmacological intervention, particularly, in adulthood.

ABSTRACT Precise development of the dendritic architecture is a critical determinant of mature neuronal circuitry. MicroRNA (miRNA)-mediated regulation of protein synthesis plays a crucial role in dendritic morphogenesis, but the role of miRNA-induced silencing complex (miRISC) protein components in this process is less studied. Here, we show an important role of a key miRISC protein, the GW182 paralog TNRC6A, in the regulation of dendritic growth. We identified a distinct brain region-specific spatiotemporal expression pattern of GW182 during rat postnatal development. We found that the window of peak GW182 expression coincides with the period of extensive dendritic growth, both in the hippocampus and cerebellum. Perturbation of GW182 function during a specific temporal window resulted in reduced dendritic growth of cultured hippocampal neurons. Mechanistically, we show that GW182 modulates dendritic growth by regulating global somatodendritic translation and actin cytoskeletal dynamics of developing neurons. Furthermore, we found that GW182 affects dendritic architecture by regulating the expression of actin modulator LIMK1. Taken together, our data reveal a previously undescribed neurodevelopmental expression pattern of GW182 and its role in dendritic morphogenesis, which involves both translational control and actin cytoskeletal rearrangement. This article has an associated First Person interview with the first author of the paper.

Background : Frontotemporal dementia type 3 (FTD3) caused by a point mutation in the charged multivesicular body protein 2B (CHMP2B), affects mitochondrial ultrastructure and function as well as endosomal-lysosomal fusion in neurons. However, there is a critical knowledge gap in understanding how mutations in CHMP2B affect astrocytes. Hence, we investigated the disease mechanisms in astrocytes derived from hiPSC with mutations in CHMP2B and their impact on neurons. Methods : To dissect the astrocyte-specific impact of mutant CHMP2B expression, we generated astrocytes from human induced pluripotent stem cells (hiPSCs) from FTD3 patients and their CRISPR/Cas 9 gene edited isogenic controls and produced heterozygous and homozygous CHMP2B-mutant hiPSC via CRISPR/Cas 9 knock-in gene editing. Additionally, we confirmed our findings in CHMP2B mutant mice. The hiPSC were subjected to astrocyte differentiation and the mutation dependent effects were investigated using immunocytochemistry, western blot, cytokine assays, transmission electron microscopy, RNA-sequencing and gas chromatography-mass spectrometry. Finally, neurons were exposed to conditioned media of mutant astrocytes and viability, growth and motility were measured. Results : To dissect the astrocyte-specific impact of mutant CHMP2B expression, we generated astrocytes from human induced pluripotent stem cells (hiPSCs) and confirmed our findings in CHMP2B mutant mice. Our findings include perturbed mitochondrial dynamics with impaired glycolysis, increased reactive oxygen species and elongated mitochondrial morphology, indicating increased mitochondrial fusion in FTD3 astrocytes. Furthermore, we identified a shift in astrocyte homeostasis triggering a reactive astrocyte phenotype and increased release of toxic cytokines. This cumulates in NF-kB pathway activation with increased production of CHF, LCN2 and C3, which cause neurodegeneration. The neurotoxic effect was investigated by exposing hiPSC-derived neurons to astrocyte-conditioned media, which severely reduced neurite outgrowth capacities. Rescue experiments targeting ROS could restore ROS levels back to normal levels, indicating that the impaired removal of abnormal mitochondria triggers the pathological cascade in CHMP2B mutant astrocytes culminating in the formation of neurotoxic reactive astrocytes. Conclusion :Our data provide mechanistic insights into how defective mitophagy causes impaired mitochondrial fission, leading to the adoption of reactive astrocyte properties with increased cytokine release, NFkB activation and elevated expression of neurotoxic proteins in FTD3.

We aimed to gauge the burden of epilepsy in China from a societal perspective by estimating the direct, indirect and intangible costs.Patients with epilepsy and controls were enrolled from two tertiary hospitals in China. Patients were asked to complete a Cost-of-Illness (COI), Willingness-to-Pay (WTP) questionnaires, two utility elicitation instruments and Mini Mental State Examination (MMSE). Healthy controls only completed WTP questionnaire, and utility instruments. Univariate analyses were performed to investigate the differences in cost on the basis of different variables, while multivariate analysis was undertaken to explore the predictors of cost/cost component.In total, 141 epilepsy patients and 323 healthy controls were recruited. The median total cost, direct cost and indirect cost due to epilepsy were US$949.29, 501.34 and 276.72, respectively. Particularly, cost of anti-epileptic drugs (AEDs) (US$394.53) followed by cost of investigations (US$59.34), cost of inpatient and outpatient care (US$9.62) accounted for the majority of the direct medical costs. While patients' (US$103.77) and caregivers' productivity costs (US$103.77) constituted the major component of indirect cost. The intangible costs in terms of WTP value (US$266.07 vs. 88.22) and utility (EQ-5D, 0.828 vs. 0.923; QWB-SA, 0.657 vs. 0.802) were both substantially higher compared to the healthy subjects.Epilepsy is a cost intensive disease in China. According to the prognostic groups, drug-resistant epilepsy generated the highest total cost whereas patients in seizure remission had the lowest cost. AED is the most costly component of direct medical cost probably due to 83% of patients being treated by new generation of AEDs.

Frontotemporal dementia type 3 (FTD3), caused by a point mutation in the charged multivesicular body protein 2B (CHMP2B), affects mitochondrial ultrastructure and the endolysosomal pathway in neurons. To dissect the astrocyte-specific impact of mutant CHMP2B expression, we generated astrocytes from human induced pluripotent stem cells (hiPSCs) and confirmed our findings in CHMP2B mutant mice. Our data provide mechanistic insights into how defective autophagy causes perturbed mitochondrial dynamics with impaired glycolysis, increased reactive oxygen species, and elongated mitochondrial morphology, indicating increased mitochondrial fusion in FTD3 astrocytes. This shift in astrocyte homeostasis triggers a reactive astrocyte phenotype and increased release of toxic cytokines, which accumulate in nuclear factor kappa b (NF-κB) pathway activation with increased production of CHF, LCN2, and C3 causing neurodegeneration.