RESUMO
BACKGROUND: TAR DNA-Binding Protein 43 (TDP-43) pathological inclusions are a distinctive feature in dozens of neurodegenerative pathologies, including limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC). Prior investigations identified vascular-associated TDP-43-positive micro-lesions, known as "Lin bodies," located on or near the brain capillaries of some individuals with LATE-NC. This study aimed to investigate the relationship between the accumulation of Lin bodies and glial cells in LATE-NC and the potential co-localization with ferritin, a protein associated with iron storage. Using multiplexed immunohistochemistry and digital pathology tools, we conducted pathological analyses to investigate the relationship between Lin bodies and glial markers (GFAP for astrocytes, IBA1 for microglia) and ferritin. Analyses were conducted on post-mortem brain tissues collected from individuals with pathologically confirmed Alzheimer's disease neuropathological changes (ADNC) and LATE-NC. RESULTS: As shown previously, there was a robust association between Lin bodies and GFAP-positive astrocyte processes. Moreover, we also observed Lin bodies frequently co-localizing with ferritin, suggesting a potential link to compromised vascular integrity. Subsequent analyses demonstrated increased astrocytosis near Lin body-positive vessels compared to those without Lin bodies, particularly in ADNC cases. These results suggest that the accumulation of Lin bodies may elicit an increased glial response, particularly among astrocytes, possibly related to impaired vascular integrity. CONCLUSIONS: Lin bodies are associated with a local reactive glial response. The strong association of Lin bodies with ferritin suggests that the loss of vascular integrity may be either a cause or a consequence of the pTDP-43 pathology. The reactive glia surrounding the affected vessels could further compromise vascular function.
Assuntos
Encéfalo , Proteínas de Ligação a DNA , Ferritinas , Humanos , Masculino , Feminino , Proteínas de Ligação a DNA/metabolismo , Idoso , Idoso de 80 Anos ou mais , Encéfalo/patologia , Encéfalo/metabolismo , Ferritinas/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Corpos de Inclusão/patologia , Corpos de Inclusão/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/metabolismo , Astrócitos/patologia , Astrócitos/metabolismo , Proteinopatias TDP-43/patologia , Proteinopatias TDP-43/metabolismo , Neuroglia/patologia , Neuroglia/metabolismo , Pessoa de Meia-Idade , DemênciaRESUMO
BACKGROUND: Cytoplasmic inclusions and loss of nuclear TDP-43 are key pathological features found in several neurodegenerative disorders, suggesting both gain- and loss-of-function mechanisms of disease. To study gain-of-function, TDP-43 overexpression has been used to generate in vitro and in vivo model systems. METHODS: We analyzed RNA-seq datasets from mouse and human neurons overexpressing TDP-43 to explore species specific splicing patterns. We explored the dynamics between TDP-43 levels and exon repression in vitro. Furthermore we analyzed human brain samples and publicly available RNA datasets to explore the relationship between exon repression and disease. RESULTS: Our study shows that excessive levels of nuclear TDP-43 protein lead to constitutive exon skipping that is largely species-specific. Furthermore, while aberrant exon skipping is detected in some human brains, it is not correlated with disease, unlike the incorporation of cryptic exons that occurs after loss of TDP-43. CONCLUSIONS: Our findings emphasize the need for caution in interpreting TDP-43 overexpression data and stress the importance of controlling for exon skipping when generating models of TDP-43 proteinopathy.
Assuntos
Proteínas de Ligação a DNA , Éxons , Humanos , Éxons/genética , Animais , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Camundongos , Neurônios/metabolismo , Encéfalo/metabolismo , Splicing de RNA/genética , Núcleo Celular/metabolismo , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologiaRESUMO
TDP-43 proteinopathies are a heterogeneous group of neurodegenerative disorders that share the presence of aberrant, misfolded and mislocalized deposits of the protein TDP-43, as in the case of amyotrophic lateral sclerosis and some, but not all, pathological variants of frontotemporal dementia. In recent years, many other diseases have been reported to have primary or secondary TDP-43 proteinopathy, such as Alzheimer's disease, Huntington's disease or the recently described limbic-predominant age-related TDP-43 encephalopathy, highlighting the need for new and accurate methods for the early detection of TDP-43 proteinopathy to help on the stratification of patients with overlapping clinical diagnosis. Currently, TDP-43 proteinopathy remains a post-mortem pathologic diagnosis. Although the main aim is to determine the pathologic TDP-43 proteinopathy in the central nervous system (CNS), the ubiquitous expression of TDP-43 in biofluids and cells outside the CNS facilitates the use of other accessible target tissues that might reflect the potential TDP-43 alterations in the brain. In this review, we describe the main developments in the early detection of TDP-43 proteinopathies, and their potential implications on diagnosis and future treatments.
Assuntos
Biomarcadores , Proteínas de Ligação a DNA , Proteinopatias TDP-43 , Humanos , Proteinopatias TDP-43/diagnóstico , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/genética , Biomarcadores/análise , Biomarcadores/metabolismo , Proteínas de Ligação a DNA/metabolismo , Encéfalo/metabolismo , Encéfalo/patologiaAssuntos
Processamento Alternativo , Esclerose Lateral Amiotrófica , Regulação para Baixo , Éxons , Humanos , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Esclerose Lateral Amiotrófica/metabolismo , Processamento Alternativo/genética , Éxons/genética , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/patologia , Proteinopatias TDP-43/metabolismo , Masculino , Feminino , Pessoa de Meia-Idade , Proteínas de Ligação a DNARESUMO
Pathogenic variants in valosin-containing protein (VCP) cause multisystem proteinopathy (MSP), a disease characterized by multiple clinical phenotypes including inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (FTD). How such diverse phenotypes are driven by pathogenic VCP variants is not known. We found that these diseases exhibit a common pathologic feature: ubiquitinated intranuclear inclusions affecting myocytes, osteoclasts, and neurons. Moreover, knock-in cell lines harboring MSP variants show a reduction in nuclear VCP. Given that MSP is associated with neuronal intranuclear inclusions comprised of TDP-43 protein, we developed a cellular model whereby proteostatic stress results in the formation of insoluble intranuclear TDP-43 aggregates. Consistent with a loss of nuclear VCP function, cells harboring MSP variants or cells treated with VCP inhibitor exhibited decreased clearance of insoluble intranuclear TDP-43 aggregates. Moreover, we identified 4 compounds that activate VCP primarily by increasing D2 ATPase activity, where pharmacologic VCP activation appears to enhance clearance of insoluble intranuclear TDP-43 aggregate. Our findings suggest that VCP function is important for nuclear protein homeostasis, that impaired nuclear proteostasis may contribute to MSP, and that VCP activation may be a potential therapeutic by virtue of enhancing the clearance of intranuclear protein aggregates.
Assuntos
Proteínas de Ligação a DNA , Miosite de Corpos de Inclusão , Proteostase , Proteína com Valosina , Animais , Humanos , Camundongos , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Demência Frontotemporal/patologia , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Demência Frontotemporal/tratamento farmacológico , Corpos de Inclusão Intranuclear/metabolismo , Corpos de Inclusão Intranuclear/patologia , Corpos de Inclusão Intranuclear/genética , Miosite de Corpos de Inclusão/metabolismo , Miosite de Corpos de Inclusão/patologia , Miosite de Corpos de Inclusão/genética , Miosite de Corpos de Inclusão/tratamento farmacológico , Osteíte Deformante/metabolismo , Osteíte Deformante/genética , Osteíte Deformante/patologia , Osteíte Deformante/tratamento farmacológico , Agregados Proteicos/efeitos dos fármacos , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologia , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/tratamento farmacológico , Proteína com Valosina/metabolismo , Proteína com Valosina/genéticaRESUMO
TAR DNA-binding protein 43 (TDP-43) proteinopathy in brain cells is the hallmark of amyotrophic lateral sclerosis (ALS) but its cause remains elusive. Asparaginase-like-1 protein (ASRGL1) cleaves isoaspartates, which alter protein folding and susceptibility to proteolysis. ASRGL1 gene harbors a copy of the human endogenous retrovirus HML-2, whose overexpression contributes to ALS pathogenesis. Here we show that ASRGL1 expression was diminished in ALS brain samples by RNA sequencing, immunohistochemistry, and western blotting. TDP-43 and ASRGL1 colocalized in neurons but, in the absence of ASRGL1, TDP-43 aggregated in the cytoplasm. TDP-43 was found to be prone to isoaspartate formation and a substrate for ASRGL1. ASRGL1 silencing triggered accumulation of misfolded, fragmented, phosphorylated and mislocalized TDP-43 in cultured neurons and motor cortex of female mice. Overexpression of ASRGL1 restored neuronal viability. Overexpression of HML-2 led to ASRGL1 silencing. Loss of ASRGL1 leading to TDP-43 aggregation may be a critical mechanism in ALS pathophysiology.
Assuntos
Esclerose Lateral Amiotrófica , Asparaginase , Proteínas de Ligação a DNA , Neurônios , Proteinopatias TDP-43 , Animais , Feminino , Humanos , Masculino , Camundongos , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Asparaginase/genética , Asparaginase/metabolismo , Autoantígenos/genética , Autoantígenos/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Córtex Motor/metabolismo , Córtex Motor/patologia , Neurônios/metabolismo , Neurônios/patologia , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologia , Proteinopatias TDP-43/genética , Retrovirus Endógenos/genética , Retrovirus Endógenos/metabolismoRESUMO
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are clinically linked major neurodegenerative diseases. Notably, TAR DNA-binding protein-43 (TDP43) accumulations are hallmark pathologies of FTD/ALS and mutations in the gene encoding TDP43 cause familial FTD/ALS. There are no cures for FTD/ALS. FTD/ALS display damage to a broad range of physiological functions, many of which are regulated by signaling between the endoplasmic reticulum (ER) and mitochondria. This signaling is mediated by the VAPB-PTPIP51 tethering proteins that serve to recruit regions of ER to the mitochondrial surface so as to facilitate inter-organelle communications. Several studies have now shown that disrupted ER-mitochondria signaling including breaking of the VAPB-PTPIP51 tethers are features of FTD/ALS and that for TDP43 and other familial genetic FTD/ALS insults, this involves activation of glycogen kinase-3ß (GSK3ß). Such findings have prompted suggestions that correcting damage to ER-mitochondria signaling and the VAPB-PTPIP51 interaction may be broadly therapeutic. Here we provide evidence to support this notion. We show that overexpression of VAPB or PTPIP51 to enhance ER-mitochondria signaling corrects mutant TDP43 induced damage to inositol 1,4,5-trisphosphate (IP3) receptor delivery of Ca2+ to mitochondria which is a primary function of the VAPB-PTPIP51 tethers, and to synaptic function. Moreover, we show that ursodeoxycholic acid (UDCA), an FDA approved drug linked to FTD/ALS and other neurodegenerative diseases therapy and whose precise therapeutic target is unclear, corrects TDP43 linked damage to the VAPB-PTPIP51 interaction. We also show that this effect involves inhibition of TDP43 mediated activation of GSK3ß. Thus, correcting damage to the VAPB-PTPIP51 tethers may have therapeutic value for FTD/ALS and other age-related neurodegenerative diseases.
Assuntos
Esclerose Lateral Amiotrófica , Demência Frontotemporal , Doenças Neurodegenerativas , Proteínas de Transporte Vesicular , Humanos , Esclerose Lateral Amiotrófica/patologia , Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Glicogênio Sintase Quinase 3 beta/metabolismo , Mitocôndrias/metabolismo , Doenças Neurodegenerativas/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Sinapses/patologia , Proteinopatias TDP-43/metabolismo , Proteínas de Transporte Vesicular/genéticaRESUMO
TDP-43 is an essential RNA-binding protein strongly implicated in the pathogenesis of neurodegenerative disorders characterized by cytoplasmic aggregates and loss of nuclear TDP-43. The protein shuttles between nucleus and cytoplasm, yet maintaining predominantly nuclear TDP-43 localization is important for TDP-43 function and for inhibiting cytoplasmic aggregation. We previously demonstrated that specific RNA binding mediates TDP-43 self-assembly and biomolecular condensation, requiring multivalent interactions via N- and C-terminal domains. Here, we show that these complexes play a key role in TDP-43 nuclear retention. TDP-43 forms macromolecular complexes with a wide range of size distribution in cells and we find that defects in RNA binding or inter-domain interactions, including phase separation, impair the assembly of the largest species. Our findings suggest that recruitment into these macromolecular complexes prevents cytoplasmic egress of TDP-43 in a size-dependent manner. Our observations uncover fundamental mechanisms controlling TDP-43 cellular homeostasis, whereby regulation of RNA-mediated self-assembly modulates TDP-43 nucleocytoplasmic distribution. Moreover, these findings highlight pathways that may be implicated in TDP-43 proteinopathies and identify potential therapeutic targets.
Assuntos
Proteínas de Ligação a DNA , Ribonucleoproteínas , Proteinopatias TDP-43 , Humanos , Esclerose Lateral Amiotrófica/genética , Proteínas de Ligação a DNA/metabolismo , Substâncias Macromoleculares/metabolismo , Ribonucleoproteínas/metabolismo , RNA , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismoRESUMO
Understanding the mechanisms that drive TDP-43 pathology is integral to combating amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD) and other neurodegenerative diseases. Here we generated a longitudinal quantitative proteomic map of the cortex from the cytoplasmic TDP-43 rNLS8 mouse model of ALS and FTLD, and developed a complementary open-access webtool, TDP-map ( https://shiny.rcc.uq.edu.au/TDP-map/ ). We identified distinct protein subsets enriched for diverse biological pathways with temporal alterations in protein abundance, including increases in protein folding factors prior to disease onset. This included increased levels of DnaJ homolog subfamily B member 5, DNAJB5, which also co-localized with TDP-43 pathology in diseased human motor cortex. DNAJB5 over-expression decreased TDP-43 aggregation in cell and cortical neuron cultures, and knockout of Dnajb5 exacerbated motor impairments caused by AAV-mediated cytoplasmic TDP-43 expression in mice. Together, these findings reveal molecular mechanisms at distinct stages of ALS and FTLD progression and suggest that protein folding factors could be protective in neurodegenerative diseases.
Assuntos
Esclerose Lateral Amiotrófica , Demência Frontotemporal , Degeneração Lobar Frontotemporal , Agregados Proteicos , Proteinopatias TDP-43 , Animais , Humanos , Camundongos , Esclerose Lateral Amiotrófica/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Demência Frontotemporal/metabolismo , Degeneração Lobar Frontotemporal/metabolismo , Neurônios/metabolismo , Proteômica , Proteinopatias TDP-43/metabolismoRESUMO
Preventing the misfolding or aggregation of transactive response DNA binding protein with 43â kDa (TDP-43) is the most actively pursued disease-modifying strategy to treat amyotrophic lateral sclerosis and other neurodegenerative diseases. In this work, we provide proof of concept that native state stabilization of TDP-43 is a viable and effective strategy for treating TDP-43 proteinopathies. Firstly, we leveraged the Cryo-EM structures of TDP-43 fibrils to design C-terminal substitutions that disrupt TDP-43 aggregation. Secondly, we showed that these substitutions (S333D/S342D) stabilize monomeric TDP-43 without altering its physiological properties. Thirdly, we demonstrated that binding native oligonucleotide ligands stabilized monomeric TDP-43 and prevented its fibrillization and phase separation in the absence of direct binding to the aggregation-prone C-terminal domain. Fourthly, we showed that the monomeric TDP-43 variant could be induced to aggregate in a controlled manner, which enabled the design and implementation of a high-throughput screening assay to identify native state stabilizers of TDP-43. Altogether, our findings demonstrate that different structural domains in TDP-43 could be exploited and targeted to develop drugs that stabilize the native state of TDP-43 and provide a platform to discover novel drugs to treat TDP-43 proteinopathies.
Assuntos
Esclerose Lateral Amiotrófica , Doenças Neurodegenerativas , Proteinopatias TDP-43 , Humanos , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo , Esclerose Lateral Amiotrófica/metabolismo , Proteínas de Ligação a DNA/químicaRESUMO
Though TDP-43 protein can be translocated into mitochondria and causes mitochondrial damage in TDP-43 proteinopathy, little is known about how TDP-43 is imported into mitochondria. In addition, whether mitochondrial damage is caused by mitochondrial mislocalization of TDP-43 or a side effect of mitochondria-mediated TDP-43 degradation remains to be investigated. Here, our bioinformatical analyses reveal that mitophagy receptor gene FUNDC1 is co-expressed with TDP-43, and both TDP-43 and FUNDC1 expression is correlated with genes associated with mitochondrial protein import pathway in brain samples of patients diagnosed with TDP-43 proteinopathy. FUNDC1 promotes mitochondrial translocation of TDP-43 possibly by promoting TDP-43-TOM70 and DNAJA2-TOM70 interactions, which is independent of the LC3 interacting region of FUNDC1 in cellular experiments. In the transgenic fly model of TDP-43 proteinopathy, overexpressing FUNDC1 enhances TDP-43 induced mitochondrial damage, whereas down-regulating FUNDC1 reverses TDP-43 induced mitochondrial damage. FUNDC1 regulates mitochondria-mediated TDP-43 degradation not only by regulating mitochondrial TDP-43 import, but also by increasing LONP1 level and by activating mitophagy, which plays important roles in cytosolic TDP-43 clearance. Together, this study not only uncovers the mechanism of mitochondrial TDP-43 import, but also unravels the active role played by mitochondria in regulating TDP-43 homeostasis.
Assuntos
Proteínas Mitocondriais , Proteinopatias TDP-43 , Humanos , Proteases Dependentes de ATP/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Mitofagia , Proteinopatias TDP-43/metabolismoRESUMO
The TDP-43 proteinopathies, which include amyotrophic lateral sclerosis and frontotemporal dementia, are a devastating group of neurodegenerative disorders that are characterized by the mislocalization and aggregation of TDP-43. Here we demonstrate that RNA-targeting CRISPR effector proteins, a programmable class of gene silencing agents that includes the Cas13 family of enzymes and Cas7-11, can be used to mitigate TDP-43 pathology when programmed to target ataxin-2, a modifier of TDP-43-associated toxicity. In addition to inhibiting the aggregation and transit of TDP-43 to stress granules, we find that the in vivo delivery of an ataxin-2-targeting Cas13 system to a mouse model of TDP-43 proteinopathy improved functional deficits, extended survival, and reduced the severity of neuropathological hallmarks. Further, we benchmark RNA-targeting CRISPR platforms against ataxin-2 and find that high-fidelity forms of Cas13 possess improved transcriptome-wide specificity compared to Cas7-11 and a first-generation effector. Our results demonstrate the potential of CRISPR technology for TDP-43 proteinopathies.
Assuntos
Esclerose Lateral Amiotrófica , Proteinopatias TDP-43 , Camundongos , Animais , Ataxina-2/genética , RNA/metabolismo , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologia , Esclerose Lateral Amiotrófica/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismoRESUMO
TDP-43 proteinopathies including frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders characterized by aggregation and mislocalization of the nucleic acid-binding protein TDP-43 and subsequent neuronal dysfunction. Here, we developed endogenous models of sporadic TDP-43 proteinopathy based on the principle that disease-associated TDP-43 acetylation at lysine 145 (K145) alters TDP-43 conformation, impairs RNA-binding capacity, and induces downstream mis-regulation of target genes. Expression of acetylation-mimic TDP-43K145Q resulted in stress-induced nuclear TDP-43 foci and loss of TDP-43 function in primary mouse and human-induced pluripotent stem cell (hiPSC)-derived cortical neurons. Mice harboring the TDP-43K145Q mutation recapitulated key hallmarks of FTLD, including progressive TDP-43 phosphorylation and insolubility, TDP-43 mis-localization, transcriptomic and splicing alterations, and cognitive dysfunction. Our study supports a model in which TDP-43 acetylation drives neuronal dysfunction and cognitive decline through aberrant splicing and transcription of critical genes that regulate synaptic plasticity and stress response signaling. The neurodegenerative cascade initiated by TDP-43 acetylation recapitulates many aspects of human FTLD and provides a new paradigm to further interrogate TDP-43 proteinopathies.
Assuntos
Esclerose Lateral Amiotrófica , Disfunção Cognitiva , Demência Frontotemporal , Degeneração Lobar Frontotemporal , Proteinopatias TDP-43 , Humanos , Animais , Camundongos , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Degeneração Lobar Frontotemporal/genética , Degeneração Lobar Frontotemporal/metabolismo , Esclerose Lateral Amiotrófica/genética , Demência Frontotemporal/genética , Modelos Animais de Doenças , RNARESUMO
BACKGROUND: Most Alzheimer's Disease (AD) cases also exhibit limbic predominant age-related TDP-43 encephalopathy neuropathological changes (LATE-NC), besides amyloid-ß plaques and neurofibrillary tangles (NFTs) containing hyperphosphorylated tau (p-tau). LATE-NC is characterized by cytoplasmic aggregates positive for pathological TDP-43 and is associated with more severe clinical outcomes in AD, compared to AD cases lacking TDP-43 pathology TDP-43: AD(LATE-NC-). Accumulating evidence suggests that TDP-43 and p-tau interact and exhibit pathological synergy during AD pathogenesis. However, it is not yet fully understood how the presence of TDP-43 affects p-tau aggregation in symptomatic AD. METHODS: In this study, we investigated the impact of TDP-43 proteinopathy on p-tau pathology with different approaches: histologically, in a human post-mortem cohort (n = 98), as well as functionally using a tau biosensor cell line and TDP-43A315T transgenic mice. RESULTS: We found that AD cases with comorbid LATE-NC, AD(LATE-NC+), have increased burdens of pretangles and/or NFTs as well as increased brain levels of p-tau199, compared to AD(LATE-NC-) cases and controls. The burden of TDP-43 pathology was also correlated with the Braak NFT stages. A tau biosensor cell line treated with sarkosyl-insoluble, brain-derived homogenates from AD(LATE-NC+) cases displayed exacerbated p-tau seeding, compared to control and AD(LATE-NC-)-treated cells. Consistently, TDP-43A315T mice injected with AD(LATE-NC+)-derived extracts also exhibited a more severe hippocampal seeding, compared to the remaining experimental groups, albeit no TDP-43 aggregation was observed. CONCLUSIONS: Our findings extend the current knowledge by supporting a functional synergy between TDP-43 and p-tau. We further demonstrate that TDP-43 pathology worsens p-tau aggregation in an indirect manner and increases its seeding potential, probably by increasing p-tau levels. This may ultimately contribute to tau-driven neurotoxicity and cell death. Because most AD cases present with comorbid LATE-NC, this study has an impact on the understanding of TDP-43 and tau pathogenesis in AD and LATE, which account for the majority of dementia cases worldwide. Moreover, it highlights the need for the development of a biomarker that detects TDP-43 during life, in order to properly stratify AD and LATE patients.
Assuntos
Doença de Alzheimer , Proteinopatias TDP-43 , Humanos , Animais , Camundongos , Proteínas tau/metabolismo , Doença de Alzheimer/metabolismo , Emaranhados Neurofibrilares/metabolismo , Proteinopatias TDP-43/metabolismo , Proteínas de Ligação a DNA/metabolismoRESUMO
Transactive response DNA binding protein of 43 kDa (TDP-43) pathology is a common proteinopathy observed among a broad spectrum of patients with neurodegenerative disease, regardless of the mutation. This suggests that protein-protein interactions of TDP-43 with other proteins may in part be responsible for the pathology. To gain better insights, we investigated TDP-43-binding proteins in each domain and correlated these interactions with canonical pathways. These investigations revealed key cellular events that are involved and are important at each domain and suggested previously identified compounds to modulate key aspects of these canonical pathways. Our approach proposes that personalized medicine approaches, which focus on perturbed cellular mechanisms would be feasible in the near future.
Assuntos
Esclerose Lateral Amiotrófica , Doenças Neurodegenerativas , Proteinopatias TDP-43 , Humanos , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologia , Medicina de Precisão , Proteínas de Ligação a DNA/metabolismo , MutaçãoRESUMO
The TAR-DNA binding protein (TDP43) is a nuclear protein whose cytoplasmic inclusions are hallmarks of Amyotrophic Lateral Sclerosis (ALS). Acute stress in cells causes TDP43 mobilization to the cytoplasm and its aggregation through different routes. Although acute stress elicits a strong phenotype, is far from recapitulating the years-long aggregation process. We applied different chronic stress protocols and described TDP43 aggregation in a human neuroblastoma cell line by combining solubility assays, thioflavin-based microscopy and flow cytometry. This approach allowed us to detect, for the first time to our knowledge in vitro, the formation of 25 kDa C-terminal fragment of TDP43, a pathogenic hallmark of ALS. Our results indicate that chronic stress, compared to the more common acute stress paradigm, better recapitulates the cell biology of TDP43 proteinopathies. Moreover, we optimized a protocol for the detection of bona fide prions in living cells, suggesting that TDP43 may form amyloids as a stress response.
Assuntos
Esclerose Lateral Amiotrófica , Proteínas de Ligação a DNA , Humanos , Esclerose Lateral Amiotrófica/genética , Linhagem Celular , Citoplasma/metabolismo , Proteínas de Ligação a DNA/metabolismo , Neuroblastoma/metabolismo , Proteinopatias TDP-43/metabolismoRESUMO
TDP-43 is an RNA-binding protein with a crucial nuclear role in splicing, and mislocalises from the nucleus to the cytoplasm in a range of neurodegenerative disorders. TDP-43 proteinopathy spans a spectrum of incurable, heterogeneous, and increasingly prevalent neurodegenerative diseases, including the amyotrophic lateral sclerosis and frontotemporal dementia disease spectrum and a significant fraction of Alzheimer's disease. There are currently no directed disease-modifying therapies for TDP-43 proteinopathies, and no way to distinguish who is affected before death. It is now clear that TDP-43 proteinopathy leads to a number of molecular changes, including the de-repression and inclusion of cryptic exons. Importantly, some of these cryptic exons lead to the loss of crucial neuronal proteins and have been shown to be key pathogenic players in disease pathogenesis (e.g., STMN2), as well as being able to modify disease progression (e.g., UNC13A). Thus, these aberrant splicing events make promising novel therapeutic targets to restore functional gene expression. Moreover, presence of these cryptic exons is highly specific to patients and areas of the brain affected by TDP-43 proteinopathy, offering the potential to develop biomarkers for early detection and stratification of patients. In summary, the discovery of cryptic exons gives hope for novel diagnostics and therapeutics on the horizon for TDP-43 proteinopathies.
Assuntos
Esclerose Lateral Amiotrófica , Demência Frontotemporal , Doenças Neurodegenerativas , Proteinopatias TDP-43 , Humanos , Demência Frontotemporal/metabolismo , Esclerose Lateral Amiotrófica/metabolismo , Proteinopatias TDP-43/metabolismo , Neurônios/metabolismo , Éxons/genética , Doenças Neurodegenerativas/metabolismoRESUMO
Inter-cellular movement of "prion-like" proteins is thought to explain propagation of neurodegeneration between cells. For example, propagation of abnormally phosphorylated cytoplasmic inclusions of TAR-DNA-Binding protein (TDP-43) is proposed to underlie progression of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). But unlike transmissible prion diseases, ALS and FTD are not infectious and injection of aggregated TDP-43 is not sufficient to cause disease. This suggests a missing component of a positive feedback necessary to sustain disease progression. We demonstrate that endogenous retrovirus (ERV) expression and TDP-43 proteinopathy are mutually reinforcing. Expression of either Drosophila mdg4-ERV (gypsy) or the human ERV, HERV-K (HML-2) are each sufficient to stimulate cytoplasmic aggregation of human TDP-43. Viral ERV transmission also triggers TDP-43 pathology in recipient cells that express physiological levels of TDP-43, whether they are in contact or at a distance. This mechanism potentially underlies the TDP-43 proteinopathy-caused neurodegenerative propagation through neuronal tissue.
Assuntos
Esclerose Lateral Amiotrófica , Retrovirus Endógenos , Demência Frontotemporal , Proteinopatias TDP-43 , Animais , Humanos , Retrovirus Endógenos/metabolismo , Esclerose Lateral Amiotrófica/genética , Demência Frontotemporal/genética , Drosophila/metabolismo , Retroalimentação , Proteinopatias TDP-43/metabolismo , Proteínas de Ligação a DNA/metabolismoRESUMO
Transactive response DNA binding protein 43 kDa (TDP-43) was discovered in 2001 as a cellular factor capable to inhibit HIV-1 gene expression. Successively, it was brought to new life as the most prevalent RNA-binding protein involved in several neurological disorders, such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Despite the fact that these two research areas could be considered very distant from each other, in recent years an increasing number of publications pointed out the existence of a potentially important connection. Indeed, the ability of TDP-43 to act as an important regulator of all aspects of RNA metabolism makes this protein also a critical factor during expression of viral RNAs. Here, we summarize all recent observations regarding the involvement of TDP-43 in viral entry, replication and latency in several viruses that include enteroviruses (EVs), Theiler's murine encephalomyelitis virus (TMEV), human immunodeficiency virus (HIV), human endogenous retroviruses (HERVs), hepatitis B virus (HBV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), West Nile virus (WNV), and herpes simplex virus-2 (HSV). In particular, in this work, we aimed to highlight the presence of similarities with the most commonly studied TDP-43 related neuronal dysfunctions.
Assuntos
Proteinopatias TDP-43 , Viroses , Animais , Humanos , Camundongos , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/metabolismo , COVID-19/genética , COVID-19/metabolismo , Proteínas de Ligação a DNA/metabolismo , Degeneração Lobar Frontotemporal/genética , Degeneração Lobar Frontotemporal/metabolismo , SARS-CoV-2/metabolismo , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo , Viroses/genética , Viroses/metabolismoRESUMO
Transactivation response DNA binding protein 43 kDa (TDP-43) and tau are major pathological proteins of neurodegenerative disorders, of which neuronal and glial aggregates are pathological hallmarks. Interestingly, accumulating evidence from neuropathological studies has shown that comorbid TDP-43 pathology is observed in a subset of patients with tauopathies, and vice versa. The concomitant pathology often spreads in a disease-specific manner and has morphological characteristics in each primary disorder. The findings from translational studies have suggested that comorbid TDP-43 or tau pathology has clinical impacts and that the comorbid pathology is not a bystander, but a part of the disease process. Shared genetic risk factors or molecular abnormalities between TDP-43 proteinopathies and tauopathies, and direct interactions between TDP-43 and tau aggregates, have been reported. Further investigations to clarify the pathogenetic factors that are shared by a broad spectrum of neurodegenerative disorders will establish key therapeutic targets.