Retromer regulates the lysosomal clearance of MAPT/tau.
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ABSTRACT:
SUBMITTER: Carosi JM
PROVIDER: S-EPMC8496733 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Defects of autophagy-lysosomal protein degradation are thought to contribute to the pathogenesis of several neurodegenerative diseases, and the accumulation of aggregation prone proteins such as MAPT/Tau in Alzheimer disease (AD). We previously showed the localization of the immunophilin FKBP4/FKBP52 in the lysosomal system of healthy human neurons suggesting its possible role in lysosome function. We also showed that decreased FKBP4 levels in AD brain neurons correlate with abnormal MAPT accumulation and aggregation. In this study, we demonstrate that FKBP4 decrease in a human neuronal cell line (SH-SY5Y) and in dorsal root ganglion (DRG) neurons from human MAPTP301S transgenic mice affected the function of the autophagy-lysosomal system under MAPT induced proteotoxic stress conditions. We show that acute MAPT accumulation in SH-SY5Y cells induced perinuclear clustering of lysosomes, triggered FKBP4 localization around the clusters and its colocalization with MAPT and MAP1LC3/LC3-positive autophagic vesicles; a similar FKBP4 localization was detected in some AD brain neurons. We demonstrate that FKBP4 decrease altered lysosomal clustering along with MAPT and MAP1LC3 secretion increase. Although ectopic FKBP4 expression could not induce autophagy under our experimental conditions, it prevented MAPT secretion after MAPT accumulation in SH-SY5Y cells implying a regulatory role of FKBP4 on MAPT secretion. Finally, we observe that FKBP4 deficiency decreased MAP1LC3-II expression and provoked MAPT accumulation during long-term stress in mouse DRG neurons. We hypothesize that the abnormal FKBP4 decrease observed in AD brain neurons might hinder autophagy efficiency and contribute to the progression of the tauopathy by modulating MAPT secretion and accumulation during MAPT pathogenesis.Abbreviations: AD: Alzheimer disease; AKT/protein kinase B: AKT serine/threonine kinase; ALP: Autophagy-lysosomal pathway; ATG: autophagy-related; BafA1: bafilomycin A1; CQ: chloroquine; CTSD: cathepsin D; DIV: days in vitro; DRG: dorsal root ganglion neurons; Dox: doxycycline; DNAJC5: DnaJ heat shock protein family (Hsp40) member C5; EL: empty lentiviral vectors; ENO2/NSE: enolase 2, gamma neuronal; FKBP4/FKBP52: FKBP prolyl isomerase 4; FTLD-Tau: frontotemporal lobar degeneration with Tau pathology; GFP: green fluorescent protein; LAMP1: lysosomal associated membrane protein 1; LDH: lactate dehydrogenase; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAPT/Tau: microtubule associated protein tau; MTT: tetrazolium salt; NFTs: neurofibrillary tangles; RPE-1: retinal pigment epithelial cells; shRNA: small-hairpin ribonucleic acid; SQSTM1/p62: sequestosome 1; SD: standard deviation; SEM: standard error of the mean; SH-SY5Y: human neuroblastoma cells; Sh1 or Sh2: Lentiviral shRNA vectors inducing FKBP4 decrease; SH-52GFP: MAPT/Tau-inducible SH-SY5Y cell line constitutively expressing FKBP4-GFP; TUBB3/βIII tubulin: tubulin beta 3 class III; UPS: ubiquitin-proteasome system.
| S-EPMC8632305 | biostudies-literature
Project description:Accumulation of toxic protein assemblies and damaged mitochondria are key features of neurodegenerative diseases, which arise in large part from clearance defects in the Macroautophagy/autophagy-lysosome system. The autophagy cargo receptor SQSTM1/p62 plays a major role in the clearance of ubiquitinated cargo through Ser403 phosphorylation by multiple kinases. However, no phosphatase is known to physiologically dephosphorylate SQSTM1 on this activating residue. RNAi-mediated knockdown and overexpression experiments using genetically encoded fluorescent reporters and defined mutant constructs in cell lines, primary neurons, and brains show that SSH1, the canonical CFL (cofilin) phosphatase, mediates the dephosphorylation of phospho-Ser403-SQSTM1, thereby impairing SQSTM1 flux and phospho-MAPT/tau clearance. The inhibitory action of SSH1 on SQSTM1 is fully dependent on SQSTM1 Ser403 phosphorylation status and is separable from SSH1-mediated CFL activation. These findings reveal a unique action of SSH1 on SQSTM1 independent of CFL and implicate an inhibitory role of SSH1 in SQSTM1-mediated clearance of autophagic cargo, including phospho-MAPT/tau. Abbreviations: AAV: adeno-associated virus; Aβ42O: amyloid β1-42 oligomers; AD: Alzheimer disease; CA3: cornu Ammonis 3; CSNK2/CK2: casein kinase 2; FCCP: 2-[2-[4-(trifluoromethoxy)phenyl]hydrazinylidene]-propanedinitrile; FTLD: frontotemporal lobar degeneration; GFP: green fluorescent protein; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; SQSTM1/p62: sequestosome-1; PLA: proximity ligation assay; RFP: red fluorescent protein; RIPA: radioimmunoprecipitation assay; shRNA: short hairpin RNA; siRNA: small interfering RNA; Ser403: Serine403; SSH1: slingshot protein phosphatase 1; TBK1: TANK-binding kinase 1; ULK: unc-51 like kinase 1.
| S-EPMC8496729 | biostudies-literature
Project description:Aggregation and cleavage are two hallmarks of Tau pathology in Alzheimer disease (AD), and abnormal fragmentation of Tau is thought to contribute to the nucleation of Tau paired helical filaments. Clearance of the abnormally modified protein could occur by the ubiquitin-proteasome and autophagy-lysosomal pathways, the two major routes for protein degradation in cells. There is a debate on which of these pathways contributes to clearance of Tau protein and of the abnormal Tau aggregates formed in AD. Here, we demonstrate in an inducible neuronal cell model of tauopathy that the autophagy-lysosomal system contributes to both Tau fragmentation into pro-aggregating forms and to clearance of Tau aggregates. Inhibition of macroautophagy enhances Tau aggregation and cytotoxicity. The Tau repeat domain can be cleaved near the N terminus by a cytosolic protease to generate the fragment F1. Additional cleavage near the C terminus by the lysosomal protease cathepsin L is required to generate Tau fragments F2 and F3 that are highly amyloidogenic and capable of seeding the aggregation of Tau. We identify in this work that components of a selective form of autophagy, chaperone-mediated autophagy, are involved in the delivery of cytosolic Tau to lysosomes for this limited cleavage. However, F1 does not fully enter the lysosome but remains associated with the lysosomal membrane. Inefficient translocation of the Tau fragments across the lysosomal membrane seems to promote formation of Tau oligomers at the surface of these organelles which may act as precursors of aggregation and interfere with lysosomal functioning.
| S-EPMC2758146 | biostudies-literature
Project description:Neurofibrillary tangles (NFTs) composed of hyperphosphorylated and misfolded tau protein are a pathological hallmark of Alzheimer's disease and other tauopathy conditions. Tau is predominantly an intraneuronal protein but is also secreted in physiological and pathological conditions. The extracellular tau has been implicated in the seeding and propagation of tau pathology and is the prime target of the current tau immunotherapy. However, truncated tau species lacking the microtubule-binding repeat (MTBR) domains essential for seeding have been shown to undergo active secretion and the mechanisms and functional consequences of the various extracellular tau are poorly understood. We report here that the transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, plays an essential role in the lysosomal exocytosis of selected tau species. TFEB loss of function significantly reduced the levels of interstitial fluid (ISF) tau in PS19 mice expressing P301S mutant tau and in conditioned media of mutant tau expressing primary neurons, while the secretion of endogenous wild-type tau was not affected. Mechanistically we found that TFEB regulates the secretion of truncated mutant tau lacking MTBR and this process is dependent on the lysosomal calcium channel TRPML1. Consistent with the seeding-incompetent nature of the truncated tau and supporting the concept that TFEB-mediated lysosomal exocytosis promotes cellular clearance, we show that reduced ISF tau in the absence of TFEB is associated with enhanced intraneuronal pathology and accelerated spreading. Our results support the idea that TFEB-mediated tau exocytosis serves as a clearance mechanism to reduce intracellular tau under pathological conditions and that effective tau immunotherapy should devoid targeting these extracellular tau species.
| S-EPMC7609570 | biostudies-literature
Project description:Vacuolar protein sorting-associated protein 35 (VPS35) is involved in retrograde transport of proteins from endosomes to trans-Golgi network. Gene mutations in VPS35 are linked to autosomal dominant late-onset Parkinson's disease (PD). Although the identification of VPS35 mutations has provided novel insight about its interactions with several PD-associated genes including leucine-rich repeat kinase 2 (LRRK2) and ?-synuclein, little information is available about the molecular mechanisms of cell death downstream of VPS35 dysfunction. In this study, we showed that VPS35 has a role in the lysosomal degradation of parkin substrate aminoacyl tRNA synthetase complex-interacting multifunctional protein 2 (AIMP2), of which accumulation leads to poly(ADP-ribose) polymerase-1 (PARP1)-dependent cell death. VPS35 was co-immunoprecipitated with AIMP2, as well as lysosome-associated membrane protein-2a (Lamp2a). Interestingly, this association was disrupted by PD-associated VPS35 mutant D620N. VPS35 overexpression prevented AIMP2-potentiated cell death and PARP1 activation in SH-SY5Y cells. More importantly, knockdown of VPS35 led to PARP1 activation and cell death, which was AIMP2 dependent. These findings provide new mechanistic insights into the role of VPS35 in the regulation of AIMP2 levels and cell death. As AIMP2 accumulation was reported in PD patient's brains and involved in dopaminergic cell death, identification of VPS35 as a novel regulator of AIMP2 clearance via lysosomal pathway provides alternative venue to control dopaminergic cell death in PD.
| S-EPMC5477581 | biostudies-literature
Project description:Tau microtubule-associated proteins, encoded by the MAPT gene, are mainly expressed in neurons participating in axonal transport and synaptic plasticity. Six major isoforms differentially expressed during cell development and differentiation are translated by alternative splicing of MAPT transcripts. Alterations in the expression of human Tau isoforms and their aggregation have been linked to several neurodegenerative diseases called tauopathies, including Alzheimer’s disease, progressive supranuclear palsy, Pick’s disease, and frontotemporal dementia with parkinsonism linked to chromosome 17. Great efforts have been dedicated in recent years to shed light on the complex regulatory mechanism of Tau splicing, with a perspective to developing new RNA-based therapies. This review summarizes the most recent contributions to the knowledge of Tau isoform expression and experimental models, highlighting the role of cis-elements and ribonucleoproteins that regulate the alternative splicing of Tau exons.
| S-EPMC9735940 | biostudies-literature
Project description:MAPT encodes the microtubule-associated protein tau, which is the main component of neurofibrillary tangles (NFTs) and found in other protein aggregates. These aggregates are among the pathological hallmarks of primary tauopathies such as frontotemporal dementia (FTD). Abnormal tau can also be observed in secondary tauopathies such as Alzheimer's disease (AD) and synucleinopathies such as Parkinson's disease (PD). On top of pathological findings, genetic data also links MAPT to these disorders. MAPT variations are a cause or risk factors for many tauopathies and synucleinopathies and are associated with certain clinical and pathological features in affected individuals. In addition to clinical, pathological, and genetic overlap, evidence also suggests that tau and alpha-synuclein may interact on the molecular level, and thus might collaborate in the neurodegenerative process. Understanding the role of MAPT variations in tauopathies and synucleinopathies is therefore essential to elucidate the role of tau in the pathogenesis and phenotype of those disorders, and ultimately to develop targeted therapies. In this review, we describe the role of MAPT genetic variations in tauopathies and synucleinopathies, several genotype-phenotype and pathological features, and discuss their implications for the classification and treatment of those disorders.
| S-EPMC9310195 | biostudies-literature
Project description:Retromer controls cellular homeostasis through regulating integral membrane protein sorting and transport and by controlling maturation of the endo-lysosomal network. Retromer dysfunction, which is linked to neurodegenerative disorders including Parkinson’s and Alzheimer’s diseases, manifests in complex cellular phenotypes, though the precise nature of this dysfunction, and its relation to neurodegeneration, remain unclear. Here, we perform the first integrated multiomics approach to provide precise insight into the impact of Retromer dysfunction on endo-lysosomal health and homeostasis within a human neuroglioma cell model. We quantify profound changes to the lysosomal proteome, indicative of broad lysosomal dysfunction and inefficient autophagic lysosome reformation, coupled with a reconfigured cell surface proteome and secretome reflective of increased lysosomal exocytosis. Through this global proteomic approach and parallel transcriptomic analysis, we provide an unprecedented integrated view of Retromer function in regulating lysosomal homeostasis and emphasise its role in neuroprotection.
2023-04-17 | GSE223292 | GEO
Project description:Tau positron emission tomography ligands provide the novel possibility to image tau pathology in vivo However, little is known about how in vivo brain uptake of tau positron emission tomography ligands relates to tau aggregates observed post-mortem. We performed tau positron emission tomography imaging with (18)F-AV-1451 in three patients harbouring a p.R406W mutation in the MAPT gene, encoding tau. This mutation results in 3- and 4-repeat tau aggregates similar to those in Alzheimer's disease, and many of the mutation carriers initially suffer from memory impairment and temporal lobe atrophy. Two patients with short disease duration and isolated memory impairment exhibited (18)F-AV-1451 uptake mainly in the hippocampus and adjacent temporal lobe regions, correlating with glucose hypometabolism in corresponding regions. One patient died after 26 years of disease duration with dementia and behavioural deficits. Pre-mortem, there was (18)F-AV-1451 uptake in the temporal and frontal lobes, as well as in the basal ganglia, which strongly correlated with the regional extent and amount of tau pathology in post-mortem brain sections. Amyloid-? ((18)F-flutemetamol) positron emission tomography scans were negative in all cases, as were stainings of brain sections for amyloid. This provides strong evidence that (18)F-AV-1451 positron emission tomography can be used to accurately quantify in vivo the regional distribution of hyperphosphorylated tau protein.
| S-EPMC4995360 | biostudies-literature
Project description:Mutations in the microtubule-associated protein tau (MAPT) underlie multiple neurodegenerative disorders, yet the pathophysiological mechanisms are unclear. A novel variant in MAPT resulting in an alanine to threonine substitution at position 152 (A152T tau) has recently been described as a significant risk factor for both frontotemporal lobar degeneration and Alzheimer's disease. Here we use complementary computational, biochemical, molecular, genetic and imaging approaches in Caenorhabditis elegans and mouse models to interrogate the effects of the A152T variant on tau function. In silico analysis suggests that a threonine at position 152 of tau confers a new phosphorylation site. This finding is borne out by mass spectrometric survey of A152T tau phosphorylation in C. elegans and mouse. Optical pulse-chase experiments of Dendra2-tau demonstrate that A152T tau and phosphomimetic A152E tau exhibit increased diffusion kinetics and the ability to traverse across the axon initial segment more efficiently than wild-type (WT) tau. A C. elegans model of tauopathy reveals that A152T and A152E tau confer patterns of developmental toxicity distinct from WT tau, likely due to differential effects on retrograde axonal transport. These data support a role for phosphorylation of the variant threonine in A152T tau toxicity and suggest a mechanism involving impaired retrograde axonal transport contributing to human neurodegenerative disease.
| S-EPMC6489414 | biostudies-literature