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Almeida LM, Oliveira Â, Oliveira JMA, Pinho BR. Stress response mechanisms in protein misfolding diseases: Profiling a cellular model of Huntington's disease. Arch Biochem Biophys 2023; 745:109711. [PMID: 37541563 DOI: 10.1016/j.abb.2023.109711] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/14/2023] [Accepted: 08/01/2023] [Indexed: 08/06/2023]
Abstract
Stress response pathways like the integrated stress response (ISR), the mitochondrial unfolded protein response (UPRmt) and the heat shock response (HSR) have emerged as part of the pathophysiology of neurodegenerative diseases, including Huntington's disease (HD) - a currently incurable disease caused by the production of mutant huntingtin (mut-Htt). Previous data from HD patients suggest that ISR is activated while UPRmt and HSR are impaired in HD. The study of these stress response pathways as potential therapeutic targets in HD requires cellular models that mimic the activation status found in HD patients of such pathways. PC12 cells with inducible expression of the N-terminal fragment of mut-Htt are among the most used cell lines to model HD, however the activation of stress responses remains unclear in this model. The goal of this study is to characterize the activation of ISR, UPRmt and HSR in this HD cell model and evaluate if it mimics the activation status found in HD patients. We show that PC12 HD cell model presents reduced levels of Hsp90 and mitochondrial chaperones, suggesting an impaired activation or function of HSR and UPRmt. This HD model also presents increased levels of phosphorylated eIF2α, the master regulator of the ISR, but overall similar levels of ATF4 and decreased levels of CHOP - transcription factors downstream to eIF2α - in comparison to control, suggesting an initial activation of ISR. These results show that this model mimics the ISR activation and the impaired UPRmt and HSR found in HD patients. This work suggests that the PC12 N-terminal HD model is suitable for studying the role of stress response pathways in the pathophysiology of HD and for exploratory studies investigating the therapeutic potential of drugs targeting stress responses.
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Affiliation(s)
- Liliana M Almeida
- UCIBIO-REQUIMTE - Applied Molecular Biosciences Unit, Mitochondria and Neurobiology Lab, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, Department of Drug Sciences, Pharmacology Lab, University of Porto, 4050-313 Porto, Portugal
| | - Ângela Oliveira
- UCIBIO-REQUIMTE - Applied Molecular Biosciences Unit, Mitochondria and Neurobiology Lab, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, Department of Drug Sciences, Pharmacology Lab, University of Porto, 4050-313 Porto, Portugal
| | - Jorge M A Oliveira
- UCIBIO-REQUIMTE - Applied Molecular Biosciences Unit, Mitochondria and Neurobiology Lab, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, Department of Drug Sciences, Pharmacology Lab, University of Porto, 4050-313 Porto, Portugal.
| | - Brígida R Pinho
- UCIBIO-REQUIMTE - Applied Molecular Biosciences Unit, Mitochondria and Neurobiology Lab, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, Department of Drug Sciences, Pharmacology Lab, University of Porto, 4050-313 Porto, Portugal.
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2
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Liu T, Woo JAA, Bukhari MZ, Wang X, Yan Y, Buosi SC, Ermekbaeva A, Sista A, Kotsiviras P, LePochat P, Chacko A, Zhao X, Kang DE. Modulation of synaptic plasticity, motor unit physiology, and TDP-43 pathology by CHCHD10. Acta Neuropathol Commun 2022; 10:95. [PMID: 35787294 PMCID: PMC9254494 DOI: 10.1186/s40478-022-01386-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/19/2022] [Indexed: 02/04/2023] Open
Abstract
Mutations in CHCHD10, a gene coding for a mitochondrial intermembrane space protein, are associated with Frontotemporal dementia (FTD)-Amyotrophic lateral sclerosis (ALS) spectrum disorders, which are pathologically characterized by cytoplasmic inclusions containing TDP-43. FTD/ALS-linked CHCHD10 mutations and TDP-43 inclusions similarly induce mitochondrial defects in respiration, fusion/fission, mtDNA stability, and cristae structure, while sizeable amounts of cytoplasmic TDP-43 aggregates are found in mitochondria. However, the mechanistic link between CHCHD10 and TDP-43 pathogenesis remains unclear. In this study, we present immunohistochemical and biochemical evidence demonstrating that insoluble CHCHD10 aggregates accumulate and colocalize with phospho-TDP-43 inclusions in brains of FTLD-TDP and AD patients, and that insoluble CHCHD10 levels tightly correlate with insoluble TDP-43 levels in control and FTLD-TDP brains. In an experimental exploration of this pathological phenotype, transgenic mice neuronally expressing FTD/ALS-linked CHCHD10R15L or CHCHDS59L mutations but not CHCHD10WT transgenic mice exhibit significantly increased CHCHD10 aggregation and phospho-TDP-43 pathology, which often colocalize within the same inclusions. Such pathologies are reflected in poor functional outcomes in long-term synaptic plasticity, motor unit physiology, and behavior in CHCHD10R15L and CHCHDS59L transgenic mice. In contrast, expression of CHCHD10WT in hTDP-43 transgenic mice (TAR4;CHCHD10WT) significantly mitigates phospho-TDP-43 pathology and rescues TDP-43-induced impairments in synaptic integrity and long-term synaptic plasticity. In isolated mitochondria, the S59L mutation induces the aggregation of resident CHCHD10S59L protein as well as the aggregation and slower turnover of recombinant TDP-43 imported into mitochondria. Likewise, in an in vitro cell-free system, the S59L mutation induces the aggregation of CHCHD10S59L protein while simultaneously enhancing the aggregation of recombinant TDP-43, as evidenced by filter trap assays and atomic force microscopy. In contrast, recombinant CHCHD10WT inhibits the growth of TDP-43 aggregates. These results in human brains, transgenic mice, and in vitro systems substantiate the role of wild type and mutant CHCHD10 in modulating mitochondrial CHCHD10 and TDP-43 pathogenesis together with associated phenotypes in long-term synaptic plasticity and motor unit physiology in mice and humans.
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Affiliation(s)
- Tian Liu
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
| | - Jung-A A Woo
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Mohammed Zaheen Bukhari
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Xinming Wang
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yan Yan
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Sara Cazzaro Buosi
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Aizara Ermekbaeva
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Apoorva Sista
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Peter Kotsiviras
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Patrick LePochat
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Ann Chacko
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - Xingyu Zhao
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA
| | - David E Kang
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
- Louis Strokes Cleveland VA Medical Center, Cleveland, OH, USA.
- Department of Molecular Medicine, Byrd Alzheimer's Center & Research Institute, USF Health Morsani College of Medicine, Tampa, FL, 33613, USA.
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3
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Tomoda T, Sumitomo A, Newton D, Sibille E. Molecular origin of somatostatin-positive neuron vulnerability. Mol Psychiatry 2022; 27:2304-2314. [PMID: 35145229 PMCID: PMC9133093 DOI: 10.1038/s41380-022-01463-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 01/11/2022] [Accepted: 01/26/2022] [Indexed: 01/27/2023]
Abstract
Reduced somatostatin (SST) and dysfunction of SST-positive (SST+) neurons are hallmarks of neurological disorders and associated with mood disturbances, but the molecular origin of SST+ neuron vulnerability is unknown. Using chronic psychosocial stress as a paradigm to induce elevated behavioral emotionality in rodents, we report a selective vulnerability of SST+ neurons through exacerbated unfolded protein response (UPR) of the endoplasmic reticulum (ER), or ER stress, in the prefrontal cortex. We next show that genetically suppressing ER stress in SST+ neurons, but not in pyramidal neurons, normalized behavioral emotionality induced by psychosocial stress. In search for intrinsic factors mediating SST+ neuron vulnerability, we found that the forced expression of the SST precursor protein (preproSST) in SST+ neurons, mimicking psychosocial stress-induced early proteomic changes, induces ER stress, whereas mature SST or processing-incompetent preproSST does not. Biochemical analyses further show that psychosocial stress induces SST protein aggregation under elevated ER stress conditions. These results demonstrate that SST processing in the ER is a SST+ neuron-intrinsic vulnerability factor under conditions of sustained or over-activated UPR, hence negatively impacting SST+ neuron functions. Combined with observations in major medical illness, such as diabetes, where excess ER processing of preproinsulin similarly causes ER stress and β cell dysfunction, this suggests a universal mechanism for proteinopathy that is induced by excess processing of native endogenous proteins, playing critical pathophysiological roles that extend to neuropsychiatric disorders.
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Affiliation(s)
- Toshifumi Tomoda
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, M5T 1R8, Canada.
| | - Akiko Sumitomo
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, M5T 1R8, Canada
| | - Dwight Newton
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, M5T 1R8, Canada
| | - Etienne Sibille
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, M5T 1R8, Canada.
- Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, M5T 1R8, Canada.
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Herrmann F, Hessmann M, Schaertl S, Berg-Rosseburg K, Brown CJ, Bursow G, Chiki A, Ebneth A, Gehrmann M, Hoeschen N, Hotze M, Jahn S, Johnson PD, Khetarpal V, Kiselyov A, Kottig K, Ladewig S, Lashuel H, Letschert S, Mills MR, Petersen K, Prime ME, Scheich C, Schmiedel G, Wityak J, Liu L, Dominguez C, Muñoz-Sanjuán I, Bard JA. Pharmacological characterization of mutant huntingtin aggregate-directed PET imaging tracer candidates. Sci Rep 2021; 11:17977. [PMID: 34504195 PMCID: PMC8429736 DOI: 10.1038/s41598-021-97334-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/24/2021] [Indexed: 12/14/2022] Open
Abstract
Huntington’s disease (HD) is caused by a CAG trinucleotide repeat expansion in the first exon of the huntingtin (HTT) gene coding for the huntingtin (HTT) protein. The misfolding and consequential aggregation of CAG-expanded mutant HTT (mHTT) underpin HD pathology. Our interest in the life cycle of HTT led us to consider the development of high-affinity small-molecule binders of HTT oligomerized/amyloid-containing species that could serve as either cellular and in vivo imaging tools or potential therapeutic agents. We recently reported the development of PET tracers CHDI-180 and CHDI-626 as suitable for imaging mHTT aggregates, and here we present an in-depth pharmacological investigation of their binding characteristics. We have implemented an array of in vitro and ex vivo radiometric binding assays using recombinant HTT, brain homogenate-derived HTT aggregates, and brain sections from mouse HD models and humans post-mortem to investigate binding affinities and selectivity against other pathological proteins from indications such as Alzheimer’s disease and spinocerebellar ataxia 1. Radioligand binding assays and autoradiography studies using brain homogenates and tissue sections from HD mouse models showed that CHDI-180 and CHDI-626 specifically bind mHTT aggregates that accumulate with age and disease progression. Finally, we characterized CHDI-180 and CHDI-626 regarding their off-target selectivity and binding affinity to beta amyloid plaques in brain sections and homogenates from Alzheimer’s disease patients.
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Affiliation(s)
| | | | | | | | - Christopher J Brown
- Evotec (U.K.) Ltd., 114 Innovation Drive, Milton Park, Abingdon, OX14 4RZ, UK
| | | | - Anass Chiki
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | | | | | | | - Madlen Hotze
- Evotec SE, Essener Bogen 7, 22419, Hamburg, Germany
| | | | - Peter D Johnson
- Evotec (U.K.) Ltd., 114 Innovation Drive, Milton Park, Abingdon, OX14 4RZ, UK
| | - Vinod Khetarpal
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA
| | - Alex Kiselyov
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA
| | | | | | - Hilal Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | | | - Matthew R Mills
- Evotec (U.K.) Ltd., 114 Innovation Drive, Milton Park, Abingdon, OX14 4RZ, UK
| | | | - Michael E Prime
- Evotec (U.K.) Ltd., 114 Innovation Drive, Milton Park, Abingdon, OX14 4RZ, UK
| | | | | | - John Wityak
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA
| | - Longbin Liu
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA
| | - Celia Dominguez
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA
| | - Ignacio Muñoz-Sanjuán
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA
| | - Jonathan A Bard
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, CA, 90045, USA.
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5
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Furtado GV, Yang J, Wu D, Papagiannopoulos CI, Terpstra HM, Kuiper EFE, Krauss S, Zhu WG, Kampinga HH, Bergink S. FOXO1 controls protein synthesis and transcript abundance of mutant polyglutamine proteins, preventing protein aggregation. Hum Mol Genet 2021; 30:996-1005. [PMID: 33822053 PMCID: PMC8170844 DOI: 10.1093/hmg/ddab095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/03/2021] [Accepted: 03/29/2021] [Indexed: 11/14/2022] Open
Abstract
FOXO1, a transcription factor downstream of the insulin/insulin like growth factor axis, has been linked to protein degradation. Elevated expression of FOXO orthologs can also prevent the aggregation of cytosine adenine guanine (CAG)-repeat disease causing polyglutamine (polyQ) proteins but whether FOXO1 targets mutant proteins for degradation is unclear. Here, we show that increased expression of FOXO1 prevents toxic polyQ aggregation in human cells while reducing FOXO1 levels has the opposite effect and accelerates it. Although FOXO1 indeed stimulates autophagy, its effect on polyQ aggregation is independent of autophagy, ubiquitin-proteasome system (UPS) mediated protein degradation and is not due to a change in mutant polyQ protein turnover. Instead, FOXO1 specifically downregulates protein synthesis rates from expanded pathogenic CAG repeat transcripts. FOXO1 orchestrates a change in the composition of proteins that occupy mutant expanded CAG transcripts, including the recruitment of IGF2BP3. This mRNA binding protein enables a FOXO1 driven decrease in pathogenic expanded CAG transcript- and protein levels, thereby reducing the initiation of amyloidogenesis. Our data thus demonstrate that FOXO1 not only preserves protein homeostasis at multiple levels, but also reduces the accumulation of aberrant RNA species that may co-contribute to the toxicity in CAG-repeat diseases.
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Affiliation(s)
- Gabriel Vasata Furtado
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Jing Yang
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Di Wu
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Christos I Papagiannopoulos
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Hanna M Terpstra
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - E F Elsiena Kuiper
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Sybille Krauss
- Faculty IV: School of Science and Technology, Institute of Biology, Human Biology / Neurobiology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Wei-Guo Zhu
- Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Nanshan District, 1066 Xueyuan Avenue, Shenzhen 508055, China
| | - Harm H Kampinga
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Steven Bergink
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
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Sarraf SA, Shah HV, Kanfer G, Pickrell AM, Holtzclaw LA, Ward ME, Youle RJ. Loss of TAX1BP1-Directed Autophagy Results in Protein Aggregate Accumulation in the Brain. Mol Cell 2020; 80:779-795.e10. [PMID: 33207181 DOI: 10.1016/j.molcel.2020.10.041] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 09/02/2020] [Accepted: 10/27/2020] [Indexed: 12/18/2022]
Abstract
Protein aggregates disrupt cellular homeostasis, causing toxicity linked to neurodegeneration. Selective autophagic elimination of aggregates is critical to protein quality control, but how aggregates are selectively targeted for degradation is unclear. We compared the requirements for autophagy receptor proteins: OPTN, NBR1, p62, NDP52, and TAX1BP1 in clearance of proteotoxic aggregates. Endogenous TAX1BP1 is recruited to and required for the clearance of stress-induced aggregates, whereas ectopic expression of TAX1BP1 increases clearance through autophagy, promoting viability of human induced pluripotent stem cell-derived neurons. In contrast, TAX1BP1 depletion sensitizes cells to several forms of aggregate-induced proteotoxicity. Furthermore, TAX1BP1 is more specifically expressed in the brain compared to other autophagy receptor proteins. In vivo, loss of TAX1BP1 results in accumulation of high molecular weight ubiquitin conjugates and premature lipofuscin accumulation in brains of young TAX1BP1 knockout mice. TAX1BP1 mediates clearance of a broad range of cytotoxic proteins indicating therapeutic potential in neurodegenerative diseases.
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Affiliation(s)
- Shireen A Sarraf
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Hetal V Shah
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD 20742, USA
| | - Gil Kanfer
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alicia M Pickrell
- School of Neuroscience, College of Science, Virginia Tech, Blacksburg, VA 24061, USA
| | - Lynne A Holtzclaw
- Microscopy and Imaging Core, Office of the Scientific Director, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Michael E Ward
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD 20742, USA.
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7
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Han J, Goldstein LA, Hou W, Watkins SC, Rabinowich H. Involvement of CASP9 (caspase 9) in IGF2R/CI-MPR endosomal transport. Autophagy 2020; 17:1393-1409. [PMID: 32397873 DOI: 10.1080/15548627.2020.1761742] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Recently, we reported that increased expression of CASP9 pro-domain, at the endosomal membrane in response to HSP90 inhibition, mediates a cell-protective effect that does not involve CASP9 apoptotic activity. We report here that a non-apoptotic activity of endosomal membrane CASP9 facilitates the retrograde transport of IGF2R/CI-MPR from the endosomes to the trans-Golgi network, indicating the involvement of CASP9 in endosomal sorting and lysosomal biogenesis. CASP9-deficient cells demonstrate the missorting of CTSD (cathepsin D) and other acid hydrolases, accumulation of late endosomes, and reduced degradation of bafilomycin A1-sensitive proteins. In the absence of CASP9, IGF2R undergoes significant degradation, and its rescue is achieved by the re-expression of a non-catalytic CASP9 mutant. This endosomal activity of CASP9 is potentially mediated by herein newly identified interactions of CASP9 with the components of the endosomal membrane transport complexes. These endosomal complexes include the retromer VPS35 and the SNX dimers, SNX1-SNX5 and SNX2-SNX6, which are involved in the IGF2R retrieval mechanism. Additionally, CASP9 interacts with HGS/HRS/ESCRT-0 and the CLTC (clathrin heavy chain) that participate in the initiation of the endosomal ESCRT degradation pathway. We propose that endosomal CASP9 inhibits the endosomal membrane degradative subdomain(s) from initiating the ESCRT-mediated degradation of IGF2R, allowing its retrieval to transport-designated endosomal membrane subdomain(s). These findings are the first to identify a cell survival, non-apoptotic function for CASP9 at the endosomal membrane, a site distinctly removed from the cytoplasmic apoptosome. Via its non-apoptotic endosomal function, CASP9 impacts the retrograde transport of IGF2R and, consequently, lysosomal biogenesis.Abbreviations: ACTB: actin beta; ATG7: autophagy related 7; BafA1: bafilomycin A1; CASP: caspase; CLTC/CHC: clathrin, heavy chain; CTSD: cathepsin D; ESCRT: endosomal sorting complexes required for transport; HEXB: hexosaminidase subunit beta; HGS/HRS/ESCRT-0: hepatocyte growth factor-regulated tyrosine kinase substrate; IGF2R/CI-MPR: insulin like growth factor 2 receptor; ILV: intraluminal vesicles; KD: knockdown; KO: knockout; M6PR/CD-MPR: mannose-6-phosphate receptor, cation dependent; MEF: murine embryonic fibroblasts; MWU: Mann-Whitney U test; PepA: pepstatin A; RAB7A: RAB7, member RAS oncogene family; SNX-BAR: sorting nexin dimers with a Bin/Amphiphysin/Rvs (BAR) domain each; TGN: trans-Golgi network; TUBB: tubulin beta; VPS26: VPS26 retromer complex component; VPS29: VPS29 retromer complex component; VPS35: VPS35 retromer complex component.
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Affiliation(s)
- Jie Han
- Departments of Pathology, University of Pittsburgh School of Medicine and the University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Leslie A Goldstein
- Departments of Pathology, University of Pittsburgh School of Medicine and the University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Wen Hou
- Departments of Pathology, University of Pittsburgh School of Medicine and the University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Simon C Watkins
- Cell Biology, University of Pittsburgh School of Medicine and the University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Hannah Rabinowich
- Departments of Pathology, University of Pittsburgh School of Medicine and the University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
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8
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Co-chaperones DNAJA1 and DNAJB6 are critical for regulation of polyglutamine aggregation. Sci Rep 2020; 10:8130. [PMID: 32424160 PMCID: PMC7235262 DOI: 10.1038/s41598-020-65046-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 04/20/2020] [Indexed: 12/23/2022] Open
Abstract
Huntington’s disease (HD) is caused by CAG repeat expansion in the huntingtin gene. The expanded polyglutamine (polyQ) repeat of the encoded protein leads to protein misfolding and aggregation, resulting in increased neuronal cell death. DNAJ co-chaperones play a crucial role in transferring misfolded/unfolded proteins to HSP70 chaperones, which play an essential role for protein folding. Here, we investigated the effect of knock out (KO) of three individual DNAJ genes in HEK293 cells expressing polyglutamine74exon1 huntingtin (polyQ74htt). Flourescence microscopy analysis revealed that KO of DNAJB6 resulted in a 5-fold increase in polyQ74htt aggregation and that DNAJA1 KO resulted in a 4-fold decrease of polyQ74htt aggregation. KO of DNAJB1 did not change the propensity of polyQ74htt to aggregate in cells. These findings where confirmed both by fluorescence microscopy analysis and filter trap assay (FTA). DNAJB6 KO cells displayed an increased rate of cell death as assessed by trypan blue exclusion and propidium iodide (PI) uptake assays. These results demonstrate that the DNAJ proteins DNAJA1 and DNAJB6 can modulate polyQ aggregation in opposite manners, and thus that fine-tuning the cellular levels of DNAJ proteins is critical for suppression of polyQ aggregation and cell survival.
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9
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Egorova PA, Bezprozvanny IB. Molecular Mechanisms and Therapeutics for Spinocerebellar Ataxia Type 2. Neurotherapeutics 2019; 16:1050-1073. [PMID: 31435879 PMCID: PMC6985344 DOI: 10.1007/s13311-019-00777-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The effective therapeutic treatment and the disease-modifying therapy for spinocerebellar ataxia type 2 (SCA2) (a progressive hereditary disease caused by an expansion of polyglutamine in the ataxin-2 protein) is not available yet. At present, only symptomatic treatment and methods of palliative care are prescribed to the patients. Many attempts were made to study the physiological, molecular, and biochemical changes in SCA2 patients and in a variety of the model systems to find new therapeutic targets for SCA2 treatment. A better understanding of the uncovered molecular mechanisms of the disease allowed the scientific community to develop strategies of potential therapy and helped to create some promising therapeutic approaches for SCA2 treatment. Recent progress in this field will be discussed in this review article.
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Affiliation(s)
- Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia.
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, ND12.200, Dallas, Texas, 75390, USA.
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