151
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Yamashita T, Kwak S. Cell death cascade and molecular therapy in ADAR2-deficient motor neurons of ALS. Neurosci Res 2018; 144:4-13. [PMID: 29944911 DOI: 10.1016/j.neures.2018.06.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/19/2018] [Accepted: 06/14/2018] [Indexed: 02/06/2023]
Abstract
TAR DNA-binding protein (TDP-43) pathology in the motor neurons is the most reliable pathological hallmark of amyotrophic lateral sclerosis (ALS), and motor neurons bearing TDP-43 pathology invariably exhibit failure in RNA editing at the GluA2 glutamine/arginine (Q/R) site due to down-regulation of adenosine deaminase acting on RNA 2 (ADAR2). Conditional ADAR2 knockout (AR2) mice display ALS-like phenotype, including progressive motor dysfunction due to loss of motor neurons. Motor neurons devoid of ADAR2 express Q/R site-unedited GluA2, and AMPA receptors with unedited GluA2 in their subunit assembly are abnormally permeable to Ca2+, which results in progressive neuronal death. Moreover, analysis of AR2 mice has demonstrated that exaggerated Ca2+ influx through the abnormal AMPA receptors overactivates calpain, a Ca2+-dependent protease, that cleaves TDP-43 into aggregation-prone fragments, which serve as seeds for TDP-43 pathology. Activated calpain also disrupts nucleo-cytoplasmic transport and gene expression by cleaving molecules involved in nucleocytoplasmic transport, including nucleoporins. These lines of evidence prompted us to develop molecular targeting therapy for ALS by normalization of disrupted intracellular environment due to ADAR2 down-regulation. In this review, we have summarized the work from our group on the cell death cascade in sporadic ALS and discussed a potential therapeutic strategy for ALS.
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Affiliation(s)
- Takenari Yamashita
- Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Shin Kwak
- Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; Department of Neurology, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
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152
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Ito D, Hatano M, Suzuki N. RNA binding proteins and the pathological cascade in ALS/FTD neurodegeneration. Sci Transl Med 2018; 9:9/415/eaah5436. [PMID: 29118263 DOI: 10.1126/scitranslmed.aah5436] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 10/13/2016] [Accepted: 04/13/2017] [Indexed: 12/12/2022]
Abstract
Advanced genetic approaches have accelerated the identification of causative genes linked to the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Most of the disease-related proteins encoded by these genes form aggregates in the cellular machineries that regulate RNA and protein quality control in cells. Cross-talk among the signaling pathways governing these machineries leads to pathological cascades mediated by the accumulation of mutant RNA binding proteins. We outline the molecular basis of ALS and FTD pathogenesis and discuss the prospects for therapeutic strategies to treat these diseases.
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Affiliation(s)
- Daisuke Ito
- Department of Neurology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
| | - Mami Hatano
- Department of Pathology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Norihiro Suzuki
- Department of Neurology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan
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153
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Abstract
Aging-related neurodegenerative diseases are progressive and fatal neurological diseases that are characterized by irreversible neuron loss and gliosis. With a growing population of aging individuals, there is a pressing need to better understand the basic biology underlying these diseases. Although diverse disease mechanisms have been implicated in neurodegeneration, a common theme of altered RNA processing has emerged as a unifying contributing factor to neurodegenerative disease. RNA processing includes a series of distinct processes, including RNA splicing, transport and stability, as well as the biogenesis of non-coding RNAs. Here, we highlight how some of these mechanisms are altered in neurodegenerative disease, including the mislocalization of RNA-binding proteins and their sequestration induced by microsatellite repeats, microRNA biogenesis alterations and defective tRNA biogenesis, as well as changes to long-intergenic non-coding RNAs. We also highlight potential therapeutic interventions for each of these mechanisms. Summary: In this At a Glance review, Edward Lee and co-authors provide an overview of RNA metabolism defects, including mislocalization of RNA-binding proteins and microRNA biogenesis alterations, that contribute to neurodegenerative disease pathology.
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Affiliation(s)
- Elaine Y Liu
- Translational Neuropathology Research Laboratories, Perelman School of Med. Univ. of Pennsylvania, 613A Stellar Chance Laboratories, Philadelphia, PA 19104, USA
| | - Christopher P Cali
- Translational Neuropathology Research Laboratories, Perelman School of Med. Univ. of Pennsylvania, 613A Stellar Chance Laboratories, Philadelphia, PA 19104, USA
| | - Edward B Lee
- Translational Neuropathology Research Laboratories, Perelman School of Med. Univ. of Pennsylvania, 613A Stellar Chance Laboratories, Philadelphia, PA 19104, USA
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154
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Nicholson AM, Zhou X, Perkerson RB, Parsons TM, Chew J, Brooks M, DeJesus-Hernandez M, Finch NA, Matchett BJ, Kurti A, Jansen-West KR, Perkerson E, Daughrity L, Castanedes-Casey M, Rousseau L, Phillips V, Hu F, Gendron TF, Murray ME, Dickson DW, Fryer JD, Petrucelli L, Rademakers R. Loss of Tmem106b is unable to ameliorate frontotemporal dementia-like phenotypes in an AAV mouse model of C9ORF72-repeat induced toxicity. Acta Neuropathol Commun 2018; 6:42. [PMID: 29855382 PMCID: PMC5984311 DOI: 10.1186/s40478-018-0545-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 12/12/2022] Open
Abstract
Loss-of-function mutations in progranulin (GRN) and a non-coding (GGGGCC)n hexanucleotide repeat expansions in C9ORF72 are the two most common genetic causes of frontotemporal lobar degeneration with aggregates of TAR DNA binding protein 43 (FTLD-TDP). TMEM106B encodes a type II transmembrane protein with unknown function. Genetic variants in TMEM106B associated with reduced TMEM106B levels have been identified as disease modifiers in individuals with GRN mutations and C9ORF72 expansions. Recently, loss of Tmem106b has been reported to protect the FTLD-like phenotypes in Grn-/- mice. Here, we generated Tmem106b-/- mice and examined whether loss of Tmem106b could rescue FTLD-like phenotypes in an AAV mouse model of C9ORF72-repeat induced toxicity. Our results showed that neither partial nor complete loss of Tmem106b was able to rescue behavioral deficits induced by the expression of (GGGGCC)66 repeats (66R). Loss of Tmem106b also failed to ameliorate 66R-induced RNA foci, dipeptide repeat protein formation and pTDP-43 pathological burden. We further found that complete loss of Tmem106b increased astrogliosis, even in the absence of 66R, and failed to rescue 66R-induced neuronal cell loss, whereas partial loss of Tmem106b significantly rescued the neuronal cell loss but not neuroinflammation induced by 66R. Finally, we showed that overexpression of 66R did not alter expression of Tmem106b and other lysosomal genes in vivo, and subsequent analyses in vitro found that transiently knocking down C9ORF72, but not overexpression of 66R, significantly increased TMEM106B and other lysosomal proteins. In summary, reducing Tmem106b levels failed to rescue FTLD-like phenotypes in a mouse model mimicking the toxic gain-of-functions associated with overexpression of 66R. Combined with the observation that loss of C9ORF72 and not 66R overexpression was associated with increased levels of TMEM106B, this work suggests that the protective TMEM106B haplotype may exert its effect in expansion carriers by counteracting lysosomal dysfunction resulting from a loss of C9ORF72.
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Affiliation(s)
- Alexandra M. Nicholson
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Xiaolai Zhou
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Ralph B. Perkerson
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Tammee M. Parsons
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Jeannie Chew
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Mieu Brooks
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Mariely DeJesus-Hernandez
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - NiCole A. Finch
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Billie J. Matchett
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Aishe Kurti
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Karen R. Jansen-West
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Emilie Perkerson
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Lillian Daughrity
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Monica Castanedes-Casey
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Linda Rousseau
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Virginia Phillips
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY 14853 USA
| | - Tania F. Gendron
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Melissa E. Murray
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Dennis W. Dickson
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - John D. Fryer
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
| | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224 USA
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155
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Cortes CJ, La Spada AR. TFEB dysregulation as a driver of autophagy dysfunction in neurodegenerative disease: Molecular mechanisms, cellular processes, and emerging therapeutic opportunities. Neurobiol Dis 2018; 122:83-93. [PMID: 29852219 DOI: 10.1016/j.nbd.2018.05.012] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 04/25/2018] [Accepted: 05/25/2018] [Indexed: 02/08/2023] Open
Abstract
Two decades ago, the recognition of protein misfolding and aggregate accumulation as defining features of neurodegenerative disease set the stage for a thorough examination of how protein quality control is maintained in neurons and in other non-neuronal cells in the central nervous system (CNS). Autophagy, a pathway of cellular self-digestion, has emerged as especially important for CNS proteostasis, and autophagy dysregulation has been documented as a defining feature of neurodegeneration in Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Transcription factor EB (TFEB) is one of the main transcriptional regulators of autophagy, as it promotes the expression of genes required for autophagosome formation, lysosome biogenesis, and lysosome function, and it is highly expressed in CNS. Over the last 7 years, TFEB has received considerable attention and TFEB dysfunction has been implicated in the pathogenesis of numerous neurodegenerative disorders. In this review, we delineate the current understanding of how TFEB dysregulation is involved in neurodegeneration, highlighting work done on AD, PD, HD, X-linked spinal & bulbar muscular atrophy, and amyotrophic lateral sclerosis. Because TFEB is a central node in defining autophagy activation status, efforts at understanding the basis for TFEB dysfunction are yielding insights into how TFEB might be targeted for therapeutic application, which may represent an exciting opportunity for the development of a treatment modality with broad application to neurodegeneration.
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Affiliation(s)
- Constanza J Cortes
- Departments of Neurology, Neurobiology, and Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA; Duke Center for Neurodegeneration & Neurotherapeutics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Albert R La Spada
- Departments of Neurology, Neurobiology, and Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA; Duke Center for Neurodegeneration & Neurotherapeutics, Duke University School of Medicine, Durham, NC 27710, USA.
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156
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Tang BL. Patient-Derived iPSCs and iNs-Shedding New Light on the Cellular Etiology of Neurodegenerative Diseases. Cells 2018; 7:38. [PMID: 29738460 PMCID: PMC5981262 DOI: 10.3390/cells7050038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/07/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) and induced neuronal (iN) cells are very much touted in terms of their potential promises in therapeutics. However, from a more fundamental perspective, iPSCs and iNs are invaluable tools for the postnatal generation of specific diseased cell types from patients, which may offer insights into disease etiology that are otherwise unobtainable with available animal or human proxies. There are two good recent examples of such important insights with diseased neurons derived via either the iPSC or iN approaches. In one, induced motor neurons (iMNs) derived from iPSCs of Amyotrophic lateral sclerosis/Frontotemporal dementia (ALS/FTD) patients with a C9orf72 repeat expansion revealed a haploinsufficiency of protein function resulting from the intronic expansion and deficiencies in motor neuron vesicular trafficking and lysosomal biogenesis that were not previously obvious in knockout mouse models. In another, striatal medium spinal neurons (MSNs) derived directly from fibroblasts of Huntington’s disease (HD) patients recapitulated age-associated disease signatures of mutant Huntingtin (mHTT) aggregation and neurodegeneration that were not prominent in neurons differentiated indirectly via iPSCs from HD patients. These results attest to the tremendous potential for pathologically accurate and mechanistically revealing disease modelling with advances in the derivation of iPSCs and iNs.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117597, Singapore.
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157
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Bingol B. Autophagy and lysosomal pathways in nervous system disorders. Mol Cell Neurosci 2018; 91:167-208. [PMID: 29729319 DOI: 10.1016/j.mcn.2018.04.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 04/26/2018] [Accepted: 04/28/2018] [Indexed: 12/12/2022] Open
Abstract
Autophagy is an evolutionarily conserved pathway for delivering cytoplasmic cargo to lysosomes for degradation. In its classically studied form, autophagy is a stress response induced by starvation to recycle building blocks for essential cellular processes. In addition, autophagy maintains basal cellular homeostasis by degrading endogenous substrates such as cytoplasmic proteins, protein aggregates, damaged organelles, as well as exogenous substrates such as bacteria and viruses. Given their important role in homeostasis, autophagy and lysosomal machinery are genetically linked to multiple human disorders such as chronic inflammatory diseases, cardiomyopathies, cancer, and neurodegenerative diseases. Multiple targets within the autophagy and lysosomal pathways offer therapeutic opportunities to benefit patients with these disorders. Here, I will summarize the mechanisms of autophagy pathways, the evidence supporting a pathogenic role for disturbed autophagy and lysosomal degradation in nervous system disorders, and the therapeutic potential of autophagy modulators in the clinic.
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Affiliation(s)
- Baris Bingol
- Genentech, Inc., Department of Neuroscience, 1 DNA Way, South San Francisco 94080, United States.
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158
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A C9orf72 ALS/FTD Ortholog Acts in Endolysosomal Degradation and Lysosomal Homeostasis. Curr Biol 2018; 28:1522-1535.e5. [PMID: 29731301 DOI: 10.1016/j.cub.2018.03.063] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 02/18/2018] [Accepted: 03/27/2018] [Indexed: 12/11/2022]
Abstract
The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is the expansion of a hexanucleotide repeat in a non-coding region of the gene C9orf72. We report that loss-of-function mutations in alfa-1, the Caenorhabditis elegans ortholog of C9orf72, cause a novel phenotypic defect: endocytosed yolk is abnormally released into the extra-embryonic space, resulting in refractile "blobs." The alfa-1 blob phenotype is partially rescued by the expression of the human C9orf72 protein, demonstrating that C9orf72 and alfa-1 function similarly. We show that alfa-1 and R144.5, which we identified from a genetic screen for mutants with the blob phenotype and renamed smcr-8, act in the degradation of endolysosomal content and subsequent lysosome reformation. The alfa-1 abnormality in lysosomal reformation results in a general dysregulation in lysosomal homeostasis, leading to defective degradation of phagosomal and autophagosomal contents. We suggest that, like alfa-1, C9orf72 functions in the degradation of endocytosed material and in the maintenance of lysosomal homeostasis. This previously undescribed function of C9orf72 explains a variety of disparate observations concerning the effects of mutations in C9orf72 and its homologs, including the abnormal accumulation of lysosomes and defective fusion of lysosomes to phagosomes. We suggest that aspects of the pathogenic and clinical features of ALS/FTD caused by C9orf72 mutations, such as altered immune responses, aggregation of autophagy targets, and excessive neuronal excitation, result from a reduction in C9orf72 gene function and consequent abnormalities in lysosomal degradation.
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159
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Walker C, El-Khamisy SF. Perturbed autophagy and DNA repair converge to promote neurodegeneration in amyotrophic lateral sclerosis and dementia. Brain 2018; 141:1247-1262. [PMID: 29584802 PMCID: PMC5917746 DOI: 10.1093/brain/awy076] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 01/16/2018] [Accepted: 02/09/2018] [Indexed: 12/13/2022] Open
Abstract
Maintaining genomic stability constitutes a major challenge facing cells. DNA breaks can arise from direct oxidative damage to the DNA backbone, the inappropriate activities of endogenous enzymes such as DNA topoisomerases, or due to transcriptionally-derived RNA/DNA hybrids (R-loops). The progressive accumulation of DNA breaks has been linked to several neurological disorders. Recently, however, several independent studies have implicated nuclear and mitochondrial genomic instability, perturbed co-transcriptional processing, and impaired cellular clearance pathways as causal and intertwined mechanisms underpinning neurodegeneration. Here, we discuss this emerging paradigm in the context of amyotrophic lateral sclerosis and frontotemporal dementia, and outline how this knowledge paves the way to novel therapeutic interventions.
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Affiliation(s)
- Callum Walker
- Krebs Institute, Department of Molecular biology and biotechnology, University of Sheffield, UK
- The Institute of Cancer Research, London, UK
| | - Sherif F El-Khamisy
- Krebs Institute, Department of Molecular biology and biotechnology, University of Sheffield, UK
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
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160
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Abstract
Autophagy is a highly conserved process and is essential for the maintenance of cellular homeostasis. Autophagy occurs at a basal level in all cells, but it can be up-regulated during stress, starvation, or infection. Misregulation of autophagy has been linked to various disorders, including cancer, neurodegeneration, and immune diseases. Here, we discuss the essential proteins acting in the formation of an autophagosome, with a focus on the ULK and VPS34 kinase complexes, phosphatidylinositol 3-phosphate effector proteins, and the transmembrane autophagy-related protein ATG9. The function and regulation of these and other autophagy-related proteins acting during formation will be addressed, in particular during amino acid starvation.
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Affiliation(s)
- Thomas J Mercer
- From the Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, United Kingdom
| | - Andrea Gubas
- From the Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, United Kingdom
| | - Sharon A Tooze
- From the Molecular Cell Biology of Autophagy Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, United Kingdom
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161
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Zhang L, Ouyang L, Guo Y, Zhang J, Liu B. UNC-51-like Kinase 1: From an Autophagic Initiator to Multifunctional Drug Target. J Med Chem 2018; 61:6491-6500. [PMID: 29509411 DOI: 10.1021/acs.jmedchem.7b01684] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
UNC-51-like kinase 1 (ULK1), known as an ortholog of the yeast Atg1, is the serine-threonine kinase and the autophagic initiator in mammals. Accumulating evidence has recently revealed the kinase domain structure of ULK1 and its post-translational modifications, as well as further elucidated its regulatory autophagic pathways and associations with diverse human diseases. Interestingly, a series of small molecules have been recently reported to target ULK1 or ULK1-modulating autophagy, which may provide a clue on exploiting them as novel candidate drugs. Taken together, this review discusses how ULK1 acts as an autophagic initiator for modulation of its intricate mechanisms, as well as how ULK1 becomes a multifunctional target for potential therapeutic applications.
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Affiliation(s)
- Lan Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital , Sichuan University and Collaborative Innovation Center of Biotherapy , Chengdu 610041 , China
| | - Liang Ouyang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital , Sichuan University and Collaborative Innovation Center of Biotherapy , Chengdu 610041 , China
| | - Yongzhi Guo
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital , Sichuan University and Collaborative Innovation Center of Biotherapy , Chengdu 610041 , China
| | - Jin Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital , Sichuan University and Collaborative Innovation Center of Biotherapy , Chengdu 610041 , China
| | - Bo Liu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital , Sichuan University and Collaborative Innovation Center of Biotherapy , Chengdu 610041 , China
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162
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Yeh TH, Liu HF, Li YW, Lu CS, Shih HY, Chiu CC, Lin SJ, Huang YC, Cheng YC. C9orf72 is essential for neurodevelopment and motility mediated by Cyclin G1. Exp Neurol 2018. [PMID: 29522758 DOI: 10.1016/j.expneurol.2018.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hexanucleotide repeat expansions in the C9orf72 gene are a common genetic cause of familial and sporadic amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the function of C9orf72 in neural development and the pathogenic mechanism underlying neurodegeneration are unknown. We found that disrupting C9orf72 expression by using C9orf72 constructs that lack the complete DENN domain result in reduced GTPase activity in zebrafish embryos, demonstrating the indispensability of the complete DENN domain. This effect was phenocopied by knocking down endogenous C9orf72 expression by using morpholinos. C9orf72-deficient zebrafish embryos exhibited impaired axonogenesis and motility defects. The C9orf72 deficiency upregulated the expression of tp53 and caused neuronal apoptosis. Knockdown Tp53 in the C9orf72-deficient embryos rescued only the apoptotic phenotype but not the phenotype with axonal and motility defects. The C9orf72 deficiency also induced ccng1 (encodes Cyclin G1) mRNA expression, and injection of a dominant-negative Cyclin G1 construct rescued the axonal impairment, apoptosis, and motility defects in the C9orf72-deficient embryos. Our results revealed the GTPase activity of C9orf72 and demonstrated that Cyclin G1 is an essential downstream mediator for C9orf72 in neural development and motility. Furthermore, downregulating Cyclin G1 was sufficient to rescue all the defects caused by C9orf72 deficiency. In summary, we revealed a novel regulatory mechanism underlying the role of C9orf72 in neurological and motility defects. This result facilitates understanding the function of the C9orf72 gene in the developing nervous system and provides a potential mechanism underlying the pathogenesis of ALS-FTD.
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Affiliation(s)
- Tu-Hsueh Yeh
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan; Section of Movement Disorders, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center, Taoyuan, Taiwan; Department of Neurology, Taipei Medical University Hospital, Taipei, Taiwan; School of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Han-Fang Liu
- College of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Wen Li
- College of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chin-Song Lu
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan; Section of Movement Disorders, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center, Taoyuan, Taiwan
| | - Hung-Yu Shih
- College of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ching-Chi Chiu
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
| | - Sheng-Jia Lin
- College of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yin-Cheng Huang
- College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Neurosurgery, Chang Gung Memorial Hospital at Linkou Medical Center, Taoyuan, Taiwan.
| | - Yi-Chuan Cheng
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
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163
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Deng Z, Sheehan P, Chen S, Yue Z. Is amyotrophic lateral sclerosis/frontotemporal dementia an autophagy disease? Mol Neurodegener 2017; 12:90. [PMID: 29282133 PMCID: PMC5746010 DOI: 10.1186/s13024-017-0232-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 12/07/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative disorders that share genetic risk factors and pathological hallmarks. Intriguingly, these shared factors result in a high rate of comorbidity of these diseases in patients. Intracellular protein aggregates are a common pathological hallmark of both diseases. Emerging evidence suggests that impaired RNA processing and disrupted protein homeostasis are two major pathogenic pathways for these diseases. Indeed, recent evidence from genetic and cellular studies of the etiology and pathogenesis of ALS-FTD has suggested that defects in autophagy may underlie various aspects of these diseases. In this review, we discuss the link between genetic mutations, autophagy dysfunction, and the pathogenesis of ALS-FTD. Although dysfunction in a variety of cellular pathways can lead to these diseases, we provide evidence that ALS-FTD is, in many cases, an autophagy disease.
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Affiliation(s)
- Zhiqiang Deng
- Brain center, Zhongnan Hospital, Wuhan University, Wuhan, Hubei, 430071, China.,Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.,Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, 10029, USA
| | - Patricia Sheehan
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, 10029, USA
| | - Shi Chen
- Brain center, Zhongnan Hospital, Wuhan University, Wuhan, Hubei, 430071, China. .,Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
| | - Zhenyu Yue
- Department of Neurology, The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, 10029, USA.
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164
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McGoldrick P, Zhang M, van Blitterswijk M, Sato C, Moreno D, Xiao S, Zhang AB, McKeever PM, Weichert A, Schneider R, Keith J, Petrucelli L, Rademakers R, Zinman L, Robertson J, Rogaeva E. Unaffected mosaic C9orf72 case: RNA foci, dipeptide proteins, but upregulated C9orf72 expression. Neurology 2017; 90:e323-e331. [PMID: 29282338 PMCID: PMC5798652 DOI: 10.1212/wnl.0000000000004865] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 10/16/2017] [Indexed: 12/11/2022] Open
Abstract
Objective Suggested C9orf72 disease mechanisms for amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration include C9orf72 haploinsufficiency, G4C2/C4G2 RNA foci, and dipeptide repeat (DPR) proteins translated from the G4C2 expansion; however, the role of small expansions (e.g., 30–90 repeats) is unknown and was investigated here. Methods We conducted a molecular and pathology study of a family in which the father (unaffected at age 90) carried a 70-repeat allele in blood DNA that expanded to ≈1,750 repeats in his children, causing ALS. Results Southern blotting revealed different degrees of mosaicism of small and large expansions in the father's tissues from the CNS. Surprisingly, in each mosaic tissue, C9orf72 mRNA levels were significantly increased compared to an ALS-affected daughter with a large expansion. Increased expression correlated with higher levels of the 70-repeat allele (the upregulation was also evident at the protein level). Remarkably, RNA foci and DPR burdens were similar or even significantly increased (in cerebellum) in the unaffected father compared to the daughter with ALS. However, the father did not display TDP-43 pathology and signs of neurodegeneration. Conclusion The presence of RNA foci and DPR pathology was insufficient for disease manifestation and TDP-43 pathology in the mosaic C9orf72 carrier with upregulated C9orf72 expression. It is important to conduct an investigation of similar cases, which could be found among unaffected parents of sporadic C9orf72 patients (e.g., 21% among Finnish patients with ALS). Caution should be taken when consulting carriers of small expansions because disease manifestation could be dependent on the extent of the somatic instability in disease-relevant tissues.
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Affiliation(s)
- Philip McGoldrick
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Ming Zhang
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Marka van Blitterswijk
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Christine Sato
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Danielle Moreno
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Shangxi Xiao
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Ashley B Zhang
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Paul M McKeever
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Anna Weichert
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Raphael Schneider
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Julia Keith
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Leonard Petrucelli
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Rosa Rademakers
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Lorne Zinman
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada
| | - Janice Robertson
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada.
| | - Ekaterina Rogaeva
- From the Tanz Centre for Research in Neurodegenerative Diseases (P.M., M.Z., C.S., D.M., S.X., A.B.Z., P.M.M., A.W., R.S., J.R., E.R.), Department of Medicine (L.Z., E.R.), Division of Neurology, and Department of Laboratory Medicine and Pathobiology (J.R.), University of Toronto, Ontario, Canada; Department of Neuroscience (M.v.B., L.P., R.R.), Mayo Clinic, Jacksonville, FL; and Sunnybrook Health Sciences Centre (J.K., L.Z.), Toronto, Ontario, Canada.
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165
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High frequency of C9orf72 hexanucleotide repeat expansion in amyotrophic lateral sclerosis patients from two founder populations sharing the same risk haplotype. Neurobiol Aging 2017; 64:160.e1-160.e7. [PMID: 29352617 DOI: 10.1016/j.neurobiolaging.2017.12.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/17/2017] [Indexed: 01/07/2023]
Abstract
We characterized the C9orf72 hexanucleotide repeat expansion (RE) mutation in amyotrophic lateral sclerosis (ALS) patients of 2 distinct origins, Ashkenazi and North Africa Jews (AJ, NAJ), its frequency, and genotype-phenotype correlations. In AJ, 80% of familial ALS (fALS) and 11% of sporadic ALS carried the RE, a total of 12.9% of all AJ-ALS compared to 0.3% in AJ controls (odds ratio [OR] = 44.3, p < 0.0001). In NAJ, 10% of fALS and 9% of sporadic ALS carried the RE, a total of 9.1% of all NAJ-ALS compared to 1% in controls (OR = 9.9, p = 0.0006). We identified a risk haplotype shared among all ALS patients, although an association with age at disease onset, fALS, and dementia were observed only in AJ. Variations were identified downstream the repeats. The risk haplotype and these polymorphisms were at high frequencies in alleles with 8 repeats or more, suggesting sequence instability. The different genotype-phenotype correlations and OR, together with the large range in age at onset, suggest that other modifiers and risk factors may affect penetrance and phenotype in ALS.
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166
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Guo W, Fumagalli L, Prior R, Van Den Bosch L. Current Advances and Limitations in Modeling ALS/FTD in a Dish Using Induced Pluripotent Stem Cells. Front Neurosci 2017; 11:671. [PMID: 29326542 PMCID: PMC5733489 DOI: 10.3389/fnins.2017.00671] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 11/20/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two age-dependent multifactorial neurodegenerative disorders, which are typically characterized by the selective death of motor neurons and cerebral cortex neurons, respectively. These two diseases share many clinical, genetic and pathological aspects. During the past decade, cell reprogramming technologies enabled researchers to generate human induced pluripotent stem cells (iPSCs) from somatic cells. This resulted in the unique opportunity to obtain specific neuronal and non-neuronal cell types from patients which could be used for basic research. Moreover, these in vitro models can mimic not only the familial forms of ALS/FTD, but also sporadic cases without known genetic cause. At present, there have been extensive technical advances in the generation of iPSCs, as well as in the differentiation procedures to obtain iPSC-derived motor neurons, cortical neurons and non-neuronal cells. The major challenge at this moment is to determine whether these iPSC-derived cells show relevant phenotypes that recapitulate complex diseases. In this review, we will summarize the work related to iPSC models of ALS and FTD. In addition, we will discuss potential drawbacks and solutions for establishing more trustworthy iPSC models for both ALS and FTD.
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Affiliation(s)
- Wenting Guo
- KU Leuven-Department of Neurosciences, Experimental Neurology and Leuven Institute for Neuroscience and Disease, Leuven, Belgium.,Laboratory of Neurobiology, VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Laura Fumagalli
- KU Leuven-Department of Neurosciences, Experimental Neurology and Leuven Institute for Neuroscience and Disease, Leuven, Belgium.,Laboratory of Neurobiology, VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Robert Prior
- KU Leuven-Department of Neurosciences, Experimental Neurology and Leuven Institute for Neuroscience and Disease, Leuven, Belgium.,Laboratory of Neurobiology, VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Ludo Van Den Bosch
- KU Leuven-Department of Neurosciences, Experimental Neurology and Leuven Institute for Neuroscience and Disease, Leuven, Belgium.,Laboratory of Neurobiology, VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium
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167
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The mammalian ULK1 complex and autophagy initiation. Essays Biochem 2017; 61:585-596. [PMID: 29233870 PMCID: PMC5869855 DOI: 10.1042/ebc20170021] [Citation(s) in RCA: 554] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/03/2017] [Accepted: 11/06/2017] [Indexed: 02/07/2023]
Abstract
Autophagy is a vital lysosomal degradation pathway that serves as a quality control mechanism. It rids the cell of damaged, toxic or excess cellular components, which if left to persist could be detrimental to the cell. It also serves as a recycling pathway to maintain protein synthesis under starvation conditions. A key initial event in autophagy is formation of the autophagosome, a unique double-membrane organelle that engulfs the cytosolic cargo destined for degradation. This step is mediated by the serine/threonine protein kinase ULK1 (unc-51-like kinase 1), which functions in a complex with at least three protein partners: FIP200 (focal adhesion kinase family interacting protein of 200 kDa), ATG (autophagy-related protein) 13 (ATG13), and ATG101. In this artcile, we focus on the regulation of the ULK1 complex during autophagy initiation. The complex pattern of upstream pathways that converge on ULK1 suggests that this complex acts as a node, converting multiple signals into autophagosome formation. Here, we review our current understanding of this regulation and in turn discuss what happens downstream, once the ULK1 complex becomes activated.
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168
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Abstract
Through autophagy intracellular material is engulfed by double membrane vesicles and delivered to lysosomes for degradation. This process requires Rab GTPases, Rab GAPs and Rab GEFs for proper membrane trafficking, since they control vesicle budding, targeting and fusion. Deregulation of autophagy contributes to several human diseases including cancer, bacterial or viral infections and neurodegeneration. This review focuses on the complex roles of the newly identified protein SMCR8 and its interaction partners during formation and maturation of autophagosomes as well as regulation of lysosomal function and further discusses their implication in neurodegenerative diseases such as ALS and FTD.
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Affiliation(s)
- Jennifer Jung
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany
| | - Christian Behrends
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany.,Munich Cluster for Systems Neurology (SyNergy), Ludwig-Maximilians-Universität München, Munich, Germany
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169
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Tang BL. Could Sirtuin Activities Modify ALS Onset and Progression? Cell Mol Neurobiol 2017; 37:1147-1160. [PMID: 27942908 PMCID: PMC11482121 DOI: 10.1007/s10571-016-0452-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/30/2016] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a complex etiology. Sirtuins have been implicated as disease-modifying factors in several neurological disorders, and in the past decade, attempts have been made to check if manipulating Sirtuin activities and levels could confer benefit in terms of neuroprotection and survival in ALS models. The efforts have largely focused on mutant SOD1, and while limited in scope, the results were largely positive. Here, the body of work linking Sirtuins with ALS is reviewed, with discussions on how Sirtuins and their activities may impact on the major etiological mechanisms of ALS. Moving forward, it is important that the potentially beneficial effect of Sirtuins in ALS disease onset and progression are assessed in ALS models with TDP-43, FUS, and C9orf72 mutations.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD7, 8 Medical Drive, Singapore, 117597, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore, 117456, Singapore.
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170
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Gao FB, Almeida S, Lopez-Gonzalez R. Dysregulated molecular pathways in amyotrophic lateral sclerosis-frontotemporal dementia spectrum disorder. EMBO J 2017; 36:2931-2950. [PMID: 28916614 DOI: 10.15252/embj.201797568] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/15/2017] [Accepted: 08/30/2017] [Indexed: 12/11/2022] Open
Abstract
Frontotemporal dementia (FTD), the second most common form of dementia in people under 65 years of age, is characterized by progressive atrophy of the frontal and/or temporal lobes. FTD overlaps extensively with the motor neuron disease amyotrophic lateral sclerosis (ALS), especially at the genetic level. Both FTD and ALS can be caused by many mutations in the same set of genes; the most prevalent of these mutations is a GGGGCC repeat expansion in the first intron of C9ORF72 As shown by recent intensive studies, some key cellular pathways are dysregulated in the ALS-FTD spectrum disorder, including autophagy, nucleocytoplasmic transport, DNA damage repair, pre-mRNA splicing, stress granule dynamics, and others. These exciting advances reveal the complexity of the pathogenic mechanisms of FTD and ALS and suggest promising molecular targets for future therapeutic interventions in these devastating disorders.
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Affiliation(s)
- Fen-Biao Gao
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Sandra Almeida
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
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171
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De Vos KJ, Hafezparast M. Neurobiology of axonal transport defects in motor neuron diseases: Opportunities for translational research? Neurobiol Dis 2017; 105:283-299. [PMID: 28235672 PMCID: PMC5536153 DOI: 10.1016/j.nbd.2017.02.004] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/26/2017] [Accepted: 02/20/2017] [Indexed: 12/12/2022] Open
Abstract
Intracellular trafficking of cargoes is an essential process to maintain the structure and function of all mammalian cell types, but especially of neurons because of their extreme axon/dendrite polarisation. Axonal transport mediates the movement of cargoes such as proteins, mRNA, lipids, membrane-bound vesicles and organelles that are mostly synthesised in the cell body and in doing so is responsible for their correct spatiotemporal distribution in the axon, for example at specialised sites such as nodes of Ranvier and synaptic terminals. In addition, axonal transport maintains the essential long-distance communication between the cell body and synaptic terminals that allows neurons to react to their surroundings via trafficking of for example signalling endosomes. Axonal transport defects are a common observation in a variety of neurodegenerative diseases, and mutations in components of the axonal transport machinery have unequivocally shown that impaired axonal transport can cause neurodegeneration (reviewed in El-Kadi et al., 2007, De Vos et al., 2008; Millecamps and Julien, 2013). Here we review our current understanding of axonal transport defects and the role they play in motor neuron diseases (MNDs) with a specific focus on the most common form of MND, amyotrophic lateral sclerosis (ALS).
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Affiliation(s)
- Kurt J De Vos
- Sheffield Institute for Translational Neuroscience, Department of Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK.
| | - Majid Hafezparast
- Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
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172
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Nassif M, Woehlbier U, Manque PA. The Enigmatic Role of C9ORF72 in Autophagy. Front Neurosci 2017; 11:442. [PMID: 28824365 PMCID: PMC5541066 DOI: 10.3389/fnins.2017.00442] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/19/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the loss of motor neurons resulting in a progressive and irreversible muscular paralysis. Advances in large-scale genetics and genomics have revealed intronic hexanucleotide repeat expansions in the gene encoding C9ORF72 as a main genetic cause of ALS and frontotemporal dementia (FTD), the second most common cause of early-onset dementia after Alzheimer's disease. Novel insights regarding the underlying pathogenic mechanisms of C9ORF72 seem to suggest a synergy of loss and gain of toxic function during disease. C9ORF72, thus far, has been found to be involved in homeostatic cellular pathways, such as actin dynamics, regulation of membrane trafficking, and macroautophagy. All these pathways have been found compromised in the pathogenesis of ALS. In this review, we aim to summarize recent findings on the function of C9ORF72, particularly in the macroautophagy pathway, hinting at a requirement to maintain the fine balance of macroautophagy to prevent neurodegeneration.
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Affiliation(s)
- Melissa Nassif
- Faculty of Science, Center for Integrative Biology, Universidad MayorSantiago, Chile.,Faculty of Science, Center for Genomics and Bioinformatics, Universidad MayorSantiago, Chile
| | - Ute Woehlbier
- Faculty of Science, Center for Integrative Biology, Universidad MayorSantiago, Chile.,Faculty of Science, Center for Genomics and Bioinformatics, Universidad MayorSantiago, Chile
| | - Patricio A Manque
- Faculty of Science, Center for Integrative Biology, Universidad MayorSantiago, Chile.,Faculty of Science, Center for Genomics and Bioinformatics, Universidad MayorSantiago, Chile
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173
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Batra R, Lee CW. Mouse Models of C9orf72 Hexanucleotide Repeat Expansion in Amyotrophic Lateral Sclerosis/ Frontotemporal Dementia. Front Cell Neurosci 2017; 11:196. [PMID: 28729824 PMCID: PMC5498553 DOI: 10.3389/fncel.2017.00196] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 06/22/2017] [Indexed: 12/13/2022] Open
Abstract
The presence of hexanucleotide repeat expansion (HRE) in the first intron of the human C9orf72 gene is the most common genetic cause underlying both familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Studies aimed at elucidating the pathogenic mechanisms associated of C9orf72 FTD and ALS (C9FTD/ALS) have focused on the hypothesis of RNA and protein toxic gain-of-function models, including formation of nuclear RNA foci containing GGGGCC (G4C2) HRE, inclusions containing dipeptide repeat proteins through a non-canonical repeat associated non-ATG (RAN) translation mechanism, and on loss-of-function of the C9orf72 protein. Immense effort to elucidate these mechanisms has been put forth and toxic gain-of-function models have especially gained attention. Various mouse models that recapitulate distinct disease-related pathological, functional, and behavioral phenotypes have been generated and characterized. Although these models express the C9orf72 HRE mutation, there are numerous differences among them, including the transgenesis approach to introduce G4C2-repeat DNA, genomic coverage of C9orf72 features in the transgene, G4C2-repeat length after genomic stabilization, spatiotemporal expression profiles of RNA foci and RAN protein aggregates, neuropathological features, and neurodegeneration-related clinical symptoms. This review aims to (1) provide an overview of the key characteristics; (2) provide insights into potential pathological factors contributing to neurotoxicity and clinical phenotypes through systematic comparison of these models.
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Affiliation(s)
- Ranjan Batra
- Department of Cellular and Molecular Medicine, University of California, San Diego, La JollaCA, United States.,Institute for Genomic Medicine, University of California, San Diego, La JollaCA, United States
| | - Chris W Lee
- Atlantic Health System, MorristownNJ, United States.,Biomedical Research Institute of New Jersey, Cedar KnollsNJ, United States
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174
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Smith EF, Shaw PJ, De Vos KJ. The role of mitochondria in amyotrophic lateral sclerosis. Neurosci Lett 2017; 710:132933. [PMID: 28669745 DOI: 10.1016/j.neulet.2017.06.052] [Citation(s) in RCA: 366] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022]
Abstract
Mitochondria are unique organelles that are essential for a variety of cellular processes including energy metabolism, calcium homeostasis, lipid biosynthesis, and apoptosis. Mitochondrial dysfunction is a prevalent feature of many neurodegenerative diseases including motor neuron disorders such as amyotrophic lateral sclerosis (ALS). Disruption of mitochondrial structure, dynamics, bioenergetics and calcium buffering has been extensively reported in ALS patients and model systems and has been suggested to be directly involved in disease pathogenesis. Here we review the alterations in mitochondrial parameters in ALS and examine the common pathways to dysfunction.
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Affiliation(s)
- Emma F Smith
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, Sheffield, S10 2HQ, UK
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, Sheffield, S10 2HQ, UK
| | - Kurt J De Vos
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, Sheffield, S10 2HQ, UK.
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175
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Madill M, McDonagh K, Ma J, Vajda A, McLoughlin P, O'Brien T, Hardiman O, Shen S. Amyotrophic lateral sclerosis patient iPSC-derived astrocytes impair autophagy via non-cell autonomous mechanisms. Mol Brain 2017; 10:22. [PMID: 28610619 PMCID: PMC5470320 DOI: 10.1186/s13041-017-0300-4] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 05/19/2017] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis, a devastating neurodegenerative disease, is characterized by the progressive loss of motor neurons and the accumulation of misfolded protein aggregates. The latter suggests impaired proteostasis may be a key factor in disease pathogenesis, though the underlying mechanisms leading to the accumulation of aggregates is unclear. Further, recent studies have indicated that motor neuron cell death may be mediated by astrocytes. Herein we demonstrate that ALS patient iPSC-derived astrocytes modulate the autophagy pathway in a non-cell autonomous manner. We demonstrate cells treated with patient derived astrocyte conditioned medium demonstrate decreased expression of LC3-II, a key adapter protein required for the selective degradation of p62 and ubiquitinated proteins targeted for degradation. We observed an increased accumulation of p62 in cells treated with patient conditioned medium, with a concomitant increase in the expression of SOD1, a protein associated with the development of ALS. Activation of autophagic mechanisms with Rapamycin reduces the accumulation of p62 puncta in cells treated with patient conditioned medium. These data suggest that patient astrocytes may modulate motor neuron cell death by impairing autophagic mechanisms, and the autophagy pathway may be a useful target in the development of novel therapeutics.
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Affiliation(s)
- Martin Madill
- Regenerative Medicine Institute (REMEDI), School of Medicine, National University of Ireland Galway, Galway, Ireland
| | - Katya McDonagh
- Regenerative Medicine Institute (REMEDI), School of Medicine, National University of Ireland Galway, Galway, Ireland
| | - Jun Ma
- Regenerative Medicine Institute (REMEDI), School of Medicine, National University of Ireland Galway, Galway, Ireland.,Anatomy Department, Hebei Medical University, Shijiazhuang, Hebei Province, People's Republic of China
| | - Alice Vajda
- Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, 152-160 Pearse Street, Dublin 2, Ireland
| | - Paul McLoughlin
- Regenerative Medicine Institute (REMEDI), School of Medicine, National University of Ireland Galway, Galway, Ireland
| | - Timothy O'Brien
- Regenerative Medicine Institute (REMEDI), School of Medicine, National University of Ireland Galway, Galway, Ireland
| | - Orla Hardiman
- Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, 152-160 Pearse Street, Dublin 2, Ireland.
| | - Sanbing Shen
- Regenerative Medicine Institute (REMEDI), School of Medicine, National University of Ireland Galway, Galway, Ireland.
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176
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Budini M, Buratti E, Morselli E, Criollo A. Autophagy and Its Impact on Neurodegenerative Diseases: New Roles for TDP-43 and C9orf72. Front Mol Neurosci 2017; 10:170. [PMID: 28611593 PMCID: PMC5447761 DOI: 10.3389/fnmol.2017.00170] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/15/2017] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a catabolic mechanism where intracellular material is degraded by vesicular structures called autophagolysosomes. Autophagy is necessary to maintain the normal function of the central nervous system (CNS), avoiding the accumulation of misfolded and aggregated proteins. Consistently, impaired autophagy has been associated with the pathogenesis of various neurodegenerative diseases. The proteins TAR DNA-binding protein-43 (TDP-43), which regulates RNA processing at different levels, and chromosome 9 open reading frame 72 (C9orf72), probably involved in membrane trafficking, are crucial in the development of neurodegenerative diseases such as Amyotrophic lateral sclerosis (ALS) and Frontotemporal Lobar Degeneration (FTLD). Additionally, recent studies have identified a role for these proteins in the control of autophagy. In this manuscript, we review what is known regarding the autophagic mechanism and discuss the involvement of TDP-43 and C9orf72 in autophagy and their impact on neurodegenerative diseases.
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Affiliation(s)
- Mauricio Budini
- Dentistry Faculty, Institute in Dentistry Sciences, University of ChileSantiago, Chile
| | - Emanuele Buratti
- International Centre for Genetic Engineering and BiotechnologyTrieste, Italy
| | - Eugenia Morselli
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de ChileSantiago, Chile
| | - Alfredo Criollo
- Dentistry Faculty, Institute in Dentistry Sciences, University of ChileSantiago, Chile.,Advanced Center for Chronic DiseasesSantiago, Chile
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177
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Webster CP, Smith EF, Shaw PJ, De Vos KJ. Protein Homeostasis in Amyotrophic Lateral Sclerosis: Therapeutic Opportunities? Front Mol Neurosci 2017; 10:123. [PMID: 28512398 PMCID: PMC5411428 DOI: 10.3389/fnmol.2017.00123] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 04/11/2017] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis (proteostasis), the correct balance between production and degradation of proteins, is essential for the health and survival of cells. Proteostasis requires an intricate network of protein quality control pathways (the proteostasis network) that work to prevent protein aggregation and maintain proteome health throughout the lifespan of the cell. Collapse of proteostasis has been implicated in the etiology of a number of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), the most common adult onset motor neuron disorder. Here, we review the evidence linking dysfunctional proteostasis to the etiology of ALS and discuss how ALS-associated insults affect the proteostasis network. Finally, we discuss the potential therapeutic benefit of proteostasis network modulation in ALS.
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Affiliation(s)
- Christopher P Webster
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - Emma F Smith
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - Kurt J De Vos
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
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178
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Moens TG, Partridge L, Isaacs AM. Genetic models of C9orf72: what is toxic? Curr Opin Genet Dev 2017; 44:92-101. [PMID: 28364657 DOI: 10.1016/j.gde.2017.01.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 01/13/2017] [Accepted: 01/18/2017] [Indexed: 12/11/2022]
Abstract
A hexanucleotide repeat expansion in the gene C9orf72 is the most common genetic cause of both amyotrophic lateral sclerosis and frontotemporal dementia. Pathogenesis may occur either due to loss of function of the C9orf72 gene, or a toxic gain of function, via the production of repetitive sense and antisense RNA and/or repetitive dipeptide repeat proteins. Recently, mouse knockouts have suggested that a loss of function of C9orf72 alone is insufficient to lead to neurodegeneration, whilst overexpression of hexanucleotide DNA is sufficient in a wide range of model systems. Additionally, models have now been created to attempt to study the effects of repetitive RNA and dipeptide proteins in isolation and thus determine their relevance to disease.
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Affiliation(s)
- Thomas G Moens
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London WC1N 3BG, UK; Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Linda Partridge
- Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College London, London WC1E 6BT, UK; Max Planck Institute for Biology of Ageing, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Adrian M Isaacs
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London WC1N 3BG, UK.
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179
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Amick J, Ferguson SM. C9orf72: At the intersection of lysosome cell biology and neurodegenerative disease. Traffic 2017; 18:267-276. [PMID: 28266105 DOI: 10.1111/tra.12477] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/02/2017] [Accepted: 03/02/2017] [Indexed: 12/13/2022]
Abstract
The discovery that expansion of a hexanucleotide repeat within a noncoding region of the C9orf72 gene causes amyotrophic lateral sclerosis and frontotemporal dementia raised questions about C9orf72 protein function and potential disease relevance. The major predicted structural feature of the C9orf72 protein is a DENN (differentially expressed in normal and neoplastic cells) domain. As DENN domains are best characterized for regulation of specific Rab GTPases, it has been proposed that C9orf72 may also act through regulation of a GTPase target. Recent genetic and cell biological studies furthermore indicate that the C9orf72 protein functions at lysosomes as part of a larger complex that also contains the Smith-Magenis chromosome region 8 (SMCR8) and WD repeat-containing protein 41 (WDR41) proteins. An important role for C9orf72 at lysosomes is supported by defects in lysosome morphology and mTOR complex 1 (mTORC1) signaling arising from C9orf72 KO in diverse model systems. Collectively, these new findings define a C9orf72-containing protein complex and a lysosomal site of action as central to C9orf72 function and provide a foundation for the elucidation of direct physiological targets for C9orf72. Further elucidation of mechanisms whereby C9orf72 regulates lysosome function will help to determine how the reductions in C9orf72 expression levels that accompany hexanucleotide repeat expansions contribute to disease pathology.
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Affiliation(s)
- Joseph Amick
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, Connecticut
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, Connecticut
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180
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Stopford MJ, Higginbottom A, Hautbergue GM, Cooper-Knock J, Mulcahy PJ, De Vos KJ, Renton AE, Pliner H, Calvo A, Chio A, Traynor BJ, Azzouz M, Heath PR, ITALSGEN Consortium, NeuroX Consortium, Kirby J, Shaw PJ. C9ORF72 hexanucleotide repeat exerts toxicity in a stable, inducible motor neuronal cell model, which is rescued by partial depletion of Pten. Hum Mol Genet 2017; 26:1133-1145. [PMID: 28158451 PMCID: PMC5409131 DOI: 10.1093/hmg/ddx022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 01/02/2017] [Accepted: 01/10/2017] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating and incurable neurodegenerative disease, characterised by progressive failure of the neuromuscular system. A (G4C2)n repeat expansion in C9ORF72 is the most common genetic cause of ALS and frontotemporal dementia (FTD). To date, the balance of evidence indicates that the (G4C2)n repeat causes toxicity and neurodegeneration via a gain-of-toxic function mechanism; either through direct RNA toxicity or through the production of toxic aggregating dipeptide repeat proteins. Here, we have generated a stable and isogenic motor neuronal NSC34 cell model with inducible expression of a (G4C2)102 repeat, to investigate the gain-of-toxic function mechanisms. The expression of the (G4C2)102 repeat produces RNA foci and also undergoes RAN translation. In addition, the expression of the (G4C2)102 repeat shows cellular toxicity. Through comparison of transcriptomic data from the cellular model with laser-captured spinal motor neurons from C9ORF72-ALS cases, we also demonstrate that the PI3K/Akt cell survival signalling pathway is dysregulated in both systems. Furthermore, partial knockdown of Pten rescues the toxicity observed in the NSC34 (G4C2)102 cellular gain-of-toxic function model of C9ORF72-ALS. Our data indicate that PTEN may provide a potential therapeutic target to ameliorate toxic effects of the (G4C2)n repeat.
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Affiliation(s)
- Matthew J. Stopford
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Adrian Higginbottom
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Guillaume M. Hautbergue
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Johnathan Cooper-Knock
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Padraig J. Mulcahy
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Kurt J. De Vos
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Alan E. Renton
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hannah Pliner
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrea Calvo
- Department of Neuroscience, University of Turin, Turin, Italy
| | - Adriano Chio
- Department of Neuroscience, University of Turin, Turin, Italy
| | - Bryan J. Traynor
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mimoun Azzouz
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Paul R. Heath
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | | | - Janine Kirby
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Pamela J. Shaw
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
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181
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Jung J, Nayak A, Schaeffer V, Starzetz T, Kirsch AK, Müller S, Dikic I, Mittelbronn M, Behrends C. Multiplex image-based autophagy RNAi screening identifies SMCR8 as ULK1 kinase activity and gene expression regulator. eLife 2017; 6. [PMID: 28195531 PMCID: PMC5323046 DOI: 10.7554/elife.23063] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 02/13/2017] [Indexed: 11/13/2022] Open
Abstract
Autophagy is an intracellular recycling and degradation pathway that depends on membrane trafficking. Rab GTPases are central for autophagy but their regulation especially through the activity of Rab GEFs remains largely elusive. We employed a RNAi screen simultaneously monitoring different populations of autophagosomes and identified 34 out of 186 Rab GTPase, GAP and GEF family members as potential autophagy regulators, amongst them SMCR8. SMCR8 uses overlapping binding regions to associate with C9ORF72 or with a C9ORF72-ULK1 kinase complex holo-assembly, which function in maturation and formation of autophagosomes, respectively. While focusing on the role of SMCR8 during autophagy initiation, we found that kinase activity and gene expression of ULK1 are increased upon SMCR8 depletion. The latter phenotype involved association of SMCR8 with the ULK1 gene locus. Global mRNA expression analysis revealed that SMCR8 regulates transcription of several other autophagy genes including WIPI2. Collectively, we established SMCR8 as multifaceted negative autophagy regulator. DOI:http://dx.doi.org/10.7554/eLife.23063.001
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Affiliation(s)
- Jennifer Jung
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany
| | - Arnab Nayak
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany
| | - Véronique Schaeffer
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany
| | | | | | - Stefan Müller
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany
| | - Ivan Dikic
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany.,Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany.,Department of Immunology and Medical Genetics, School of Medicine, University of Split, Split, Croatia
| | - Michel Mittelbronn
- Neurological Institute, Goethe University, Frankfurt, Germany.,German Cancer Consortium, Heidelberg, Germany.,German Cancer Research Center, Heidelberg, Germany
| | - Christian Behrends
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt, Germany.,Munich Cluster for Systems Neurology, Ludwig-Maximilians-University Munich, Munich, Germany
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182
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Sakkas LI, Bogdanos DP, Kousvelari EE. Loss of C9orf72 function leads to autoimmunity. ANNALS OF TRANSLATIONAL MEDICINE 2017; 5:60. [PMID: 28251139 PMCID: PMC5326657 DOI: 10.21037/atm.2017.01.33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 11/28/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Lazaros I. Sakkas
- Department of Rheumatology and clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Dimitrios P. Bogdanos
- Department of Rheumatology and clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Eleni E. Kousvelari
- Dental School, National and Kapodistrian University of Athens, Athens, Greece
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183
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Elevated TMEM106B levels exaggerate lipofuscin accumulation and lysosomal dysfunction in aged mice with progranulin deficiency. Acta Neuropathol Commun 2017; 5:9. [PMID: 28126008 PMCID: PMC5270347 DOI: 10.1186/s40478-017-0412-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/14/2017] [Indexed: 12/12/2022] Open
Abstract
Mutations resulting in haploinsufficiency of progranulin (PGRN) cause frontotemporal lobar degeneration with TDP-43-positive inclusions (FTLD-TDP), a devastating neurodegenerative disease. Accumulating evidence suggest a crucial role of progranulin in maintaining proper lysosomal function during aging. TMEM106B has been identified as a risk factor for frontotemporal lobar degeneration with progranulin mutations and elevated mRNA and protein levels of TMEM106B are associated with increased risk for frontotemporal lobar degeneration. Increased levels of TMEM106B alter lysosomal morphology and interfere with lysosomal degradation. However, how progranulin and TMEM106B interact to regulate lysosomal function and frontotemporal lobar degeneration (FTLD) disease progression is still unclear. Here we report that progranulin deficiency leads to increased TMEM106B protein levels in the mouse cortex with aging. To mimic elevated levels of TMEM106B in frontotemporal lobar degeneration (FTLD) cases, we generated transgenic mice expressing TMEM106B under the neuronal specific promoter, CamKII. Surprisingly, we found that the total protein levels of TMEM106B are not altered despite the expression of the TMEM106B transgene at mRNA and protein levels, suggesting a tight regulation of TMEM106B protein levels in the mouse brain. However, progranulin deficiency results in accumulation of TMEM106B protein from the transgene expression during aging, which is accompanied by exaggerated lysosomal abnormalities and increased lipofuscin accumulation. In summary, our mouse model nicely recapitulates the interaction between progranulin and TMEM106B in human patients and supports a critical role of lysosomal dysfunction in the frontotemporal lobar degeneration (FTLD) disease progression.
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184
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Tang BL. Rabs, Membrane Dynamics, and Parkinson's Disease. J Cell Physiol 2016; 232:1626-1633. [DOI: 10.1002/jcp.25713] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine; National University of Singapore; Singapore 117597
- NUS Graduate School for Integrative Sciences and Engineering; National University of Singapore; Singapore 117456
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185
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Ugolino J, Ji YJ, Conchina K, Chu J, Nirujogi RS, Pandey A, Brady NR, Hamacher-Brady A, Wang J. Loss of C9orf72 Enhances Autophagic Activity via Deregulated mTOR and TFEB Signaling. PLoS Genet 2016; 12:e1006443. [PMID: 27875531 PMCID: PMC5119725 DOI: 10.1371/journal.pgen.1006443] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 10/21/2016] [Indexed: 12/13/2022] Open
Abstract
The most common cause of the neurodegenerative diseases amyotrophic lateral sclerosis and frontotemporal dementia is a hexanucleotide repeat expansion in C9orf72. Here we report a study of the C9orf72 protein by examining the consequences of loss of C9orf72 functions. Deletion of one or both alleles of the C9orf72 gene in mice causes age-dependent lethality phenotypes. We demonstrate that C9orf72 regulates nutrient sensing as the loss of C9orf72 decreases phosphorylation of the mTOR substrate S6K1. The transcription factor EB (TFEB), a master regulator of lysosomal and autophagy genes, which is negatively regulated by mTOR, is substantially up-regulated in C9orf72 loss-of-function animal and cellular models. Consistent with reduced mTOR activity and increased TFEB levels, loss of C9orf72 enhances autophagic flux, suggesting that C9orf72 is a negative regulator of autophagy. We identified a protein complex consisting of C9orf72 and SMCR8, both of which are homologous to DENN-like proteins. The depletion of C9orf72 or SMCR8 leads to significant down-regulation of each other’s protein level. Loss of SMCR8 alters mTOR signaling and autophagy. These results demonstrate that the C9orf72-SMCR8 protein complex functions in the regulation of metabolism and provide evidence that loss of C9orf72 function may contribute to the pathogenesis of relevant diseases. C9orf72 is one of many uncharacterized genes in the human genome. The presence of repeated nucleotides in the non-coding region of the C9orf72 gene (GGGGCC) has been linked to the neurodegenerative diseases Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal dementia (FTD). However, how the presence of these repeats in the gene leads to neurodegeneration is unknown. One possible explanation is that the repeats lead to a reduced expression of the C9orf72 gene and loss of function of the C9orf72 protein. Although C9orf72 is well-conserved among multi-cellular organisms, its protein function remains to be determined. In this study, we demonstrated that loss of C9orf72 reduces mTOR signaling and enhances autophagy. mTOR signaling and autophagy are important for the cellular maintenance of metabolic balances, especially under stress conditions. C9orf72 protein exists in a complex with another DENN-like protein, SMCR8, which also regulates mTOR signaling and autophagy. We generated mice lacking C9orf72, which died prematurely and showed dramatic upregulation of TFEB, a crucial transcriptional regulator of autophagy and lysosomal genes, that integrates mTOR activity state and autophagic capacity. We propose that C9orf72 function is important for metabolic control and its deficiency can contribute to the development of neurodegenerative diseases.
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Affiliation(s)
- Janet Ugolino
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, and Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Yon Ju Ji
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, and Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Karen Conchina
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, and Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Justin Chu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, and Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Raja Sekhar Nirujogi
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Akhilesh Pandey
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Nathan R. Brady
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Maryland, United States of America
| | - Anne Hamacher-Brady
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Maryland, United States of America
| | - Jiou Wang
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, and Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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186
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Webster CP, Smith EF, Grierson AJ, De Vos KJ. C9orf72 plays a central role in Rab GTPase-dependent regulation of autophagy. Small GTPases 2016; 9:399-408. [PMID: 27768524 PMCID: PMC5997165 DOI: 10.1080/21541248.2016.1240495] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A GGGGCC hexanucleotide repeat expansion in the first intron of the C9orf72 gene is the most common genetic defect associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9ALS/FTD). Haploinsufficiency and a resulting loss of C9orf72 protein function has been suggested as a possible pathogenic mechanism in C9ALS/FTD. C9ALS/FTD patients exhibit specific ubiquitin and p62/sequestosome-1 positive but TDP-43 negative inclusions in the cerebellum and hippocampus, indicating possible autophagy deficits in these patients. In a recent study, we investigated this possibility by reducing expression of C9orf72 in cell lines and primary neurons and found that C9orf72 regulates the initiation of autophagy. C9orf72 interacts with Rab1a, preferentially in its GTP-bound state, as well as the ULK1 autophagy initiation complex. As an effector of Rab1a, C9orf72 controls the Rab1a-dependent trafficking of the ULK1 initiation complex prior to autophagosome formation. In line with this function, C9orf72 depletion in cell lines and primary neurons caused the accumulation of p62/sequestosome-1-positive inclusions. In support of a role in disease pathogenesis, C9ALS/FTD patient-derived iNeurons showed markedly reduced levels of autophagy. In this Commentary we summarise recent findings supporting the key role of C9orf72 in Rab GTPase-dependent regulation of autophagy and discuss autophagy dysregulation as a pathogenic mechanism in ALS/FTD.
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Affiliation(s)
- Christopher P Webster
- a Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience , University of Sheffield , Sheffield , UK
| | - Emma F Smith
- a Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience , University of Sheffield , Sheffield , UK
| | - Andrew J Grierson
- a Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience , University of Sheffield , Sheffield , UK
| | - Kurt J De Vos
- a Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience , University of Sheffield , Sheffield , UK
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