1
|
Palumbo RJ, Yang Y, Feigon J, Hanes SD. Catalytic activity of the Bin3/MePCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. Genetics 2024; 226:iyad203. [PMID: 37982586 PMCID: PMC10763541 DOI: 10.1093/genetics/iyad203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/27/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023] Open
Abstract
Methylphosphate Capping Enzyme (MePCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MePCE in vitro, little is known about its functions in vivo, or what roles-if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MePCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MePCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MePCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
Collapse
Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Yuan Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| |
Collapse
|
2
|
Palumbo RJ, Hanes SD. Catalytic activity of the Bin3/MEPCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543302. [PMID: 37333392 PMCID: PMC10274667 DOI: 10.1101/2023.06.01.543302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Methylphosphate Capping Enzyme (MEPCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MEPCE in vitro, little is known about its functions in vivo, or what roles- if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MEPCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MEPCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MEPCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
Collapse
Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
| |
Collapse
|
3
|
Gomes NA, Lima e Silva FDC, de Oliveira Volpe CM, Villar-Delfino PH, de Sousa CF, Rocha-Silva F, Nogueira-Machado JA. Overexpression of mTOR in Leukocytes from ALS8 Patients. Curr Neuropharmacol 2023; 21:482-490. [PMID: 36722478 PMCID: PMC10207909 DOI: 10.2174/1570159x21666230201151016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 12/08/2022] [Accepted: 12/15/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND The mutated VAPBP56S (vesicle B associated membrane protein - P56S) protein has been described in a Brazilian family and classified as Amyotrophic Lateral Sclerosis type 8 (ALS8). OBJECTIVE We aimed to study altered biochemical and immunological parameters in cells from ALS8 patients to identify possible biomarkers or therapeutic targets. METHODS Wild-type VAPB, VAPBP56S, mTOR, proinflammatory cytokines, and oxidant/reducing levels in serum, leucocytes, and cellular lysate from ALS8 patients and health Controls were performed by ELISA, fluorimetry, and spectrophotometry. RESULTS Our results showed similar levels of mutant and wild-type VAPB in serum and intracellular lysate (p > 0.05) when ALS8 patients and Controls were compared. IL-1β, IL-6, and IL-18 levels in patients and Controls showed no difference, suggesting an absence of peripheral inflammation (p > 0.05). Oxidative metabolic response, assessed by mitochondrial ROS production, and reductive response by MTT reduction, were higher in the ALS8 group compared to Controls (p < 0.05), although not characterizing typical oxidative stress in ALS8 patients. Total mTOR levels (phosphorylated or non-phosphorylated) of ALS8 patients were significantly lower in serum and higher in intracellular lysate than the mean equivalents in Controls (p < 0.05). A similar result was observed when we quantified the phosphorylated protein (p < 0.05). CONCLUSION We demonstrate the possibility of using these biochemical and immunological parameters as potential therapeutic targets or biomarkers. Furthermore, by hypothesis, we suggest a hormetic response in which both VAPB forms could coexist in different proportions throughout life. The mutated VAPBP56S production would increase with aging and predominate over the wild-type VAPB levels, determining the onset of symptoms and aggravating the disease.
Collapse
Affiliation(s)
- Nathália Augusta Gomes
- Programa de Pós-Graduação Stricto Sensu em Medicina/Biomedicina, Faculdade Santa Casa de BH, Belo Horizonte, Minas Gerais, Brazil
| | | | - Caroline Maria de Oliveira Volpe
- Programa de Pós-Graduação Stricto Sensu em Medicina/Biomedicina, Faculdade Santa Casa de BH, Belo Horizonte, Minas Gerais, Brazil
| | - Pedro Henrique Villar-Delfino
- Programa de Pós-Graduação Stricto Sensu em Medicina/Biomedicina, Faculdade Santa Casa de BH, Belo Horizonte, Minas Gerais, Brazil
| | - Camila Ferreira de Sousa
- Programa de Pós-Graduação Stricto Sensu em Medicina/Biomedicina, Faculdade Santa Casa de BH, Belo Horizonte, Minas Gerais, Brazil
| | - Fabiana Rocha-Silva
- Programa de Pós-Graduação Stricto Sensu em Medicina/Biomedicina, Faculdade Santa Casa de BH, Belo Horizonte, Minas Gerais, Brazil
| | - José Augusto Nogueira-Machado
- Programa de Pós-Graduação Stricto Sensu em Medicina/Biomedicina, Faculdade Santa Casa de BH, Belo Horizonte, Minas Gerais, Brazil
| |
Collapse
|
4
|
Karagas NE, Gupta R, Rastegari E, Tan KL, Leung HH, Bellen HJ, Venkatachalam K, Wong CO. Loss of Activity-Induced Mitochondrial ATP Production Underlies the Synaptic Defects in a Drosophila Model of ALS. J Neurosci 2022; 42:8019-8037. [PMID: 36261266 PMCID: PMC9617612 DOI: 10.1523/jneurosci.2456-21.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 08/23/2022] [Accepted: 08/27/2022] [Indexed: 11/21/2022] Open
Abstract
Mutations in the gene encoding vesicle-associated membrane protein B (VAPB) cause a familial form of amyotrophic lateral sclerosis (ALS). Expression of an ALS-related variant of vapb (vapbP58S ) in Drosophila motor neurons results in morphologic changes at the larval neuromuscular junction (NMJ) characterized by the appearance of fewer, but larger, presynaptic boutons. Although diminished microtubule stability is known to underlie these morphologic changes, a mechanism for the loss of presynaptic microtubules has been lacking. By studying flies of both sexes, we demonstrate the suppression of vapbP58S -induced changes in NMJ morphology by either a loss of endoplasmic reticulum (ER) Ca2+ release channels or the inhibition Ca2+/calmodulin (CaM)-activated kinase II (CaMKII). These data suggest that decreased stability of presynaptic microtubules at vapbP58S NMJs results from hyperactivation of CaMKII because of elevated cytosolic [Ca2+]. We attribute the Ca2+ dyshomeostasis to delayed extrusion of cytosolic Ca2+ Suggesting that this defect in Ca2+ extrusion arose from an insufficient response to the bioenergetic demand of neural activity, depolarization-induced mitochondrial ATP production was diminished in vapbP58S neurons. These findings point to bioenergetic dysfunction as a potential cause for the synaptic defects in vapbP58S -expressing motor neurons.SIGNIFICANCE STATEMENT Whether the synchrony between the rates of ATP production and demand is lost in degenerating neurons remains poorly understood. We report that expression of a gene equivalent to an amyotrophic lateral sclerosis (ALS)-causing variant of vesicle-associated membrane protein B (VAPB) in fly neurons decouples mitochondrial ATP production from neuronal activity. Consequently, levels of ATP in mutant neurons are unable to keep up with the bioenergetic burden of neuronal activity. Reduced rate of Ca2+ extrusion, which could result from insufficient energy to power Ca2+ ATPases, results in the accumulation of residual Ca2+ in mutant neurons and leads to alterations in synaptic vesicle (SV) release and synapse development. These findings suggest that synaptic defects in a model of ALS arise from the loss of activity-induced ATP production.
Collapse
Affiliation(s)
- Nicholas E Karagas
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Sciences Center, Houston, Texas 77030
- Graduate Program in Biochemistry and Cell Biology, MD Anderson Cancer Center and University of Texas Health Sciences Center Graduate School of Biomedical Sciences, Houston, TX, 77030
| | - Richa Gupta
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Sciences Center, Houston, Texas 77030
| | - Elham Rastegari
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Sciences Center, Houston, Texas 77030
| | - Kai Li Tan
- Departments of Molecular and Human Genetics and Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Graduate Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
- Duncan Neurological Research Institute, Texas Children Hospital, Houston, Texas 77030
| | - Ho Hang Leung
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| | - Hugo J Bellen
- Departments of Molecular and Human Genetics and Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Graduate Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
- Duncan Neurological Research Institute, Texas Children Hospital, Houston, Texas 77030
| | - Kartik Venkatachalam
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Sciences Center, Houston, Texas 77030
- Graduate Program in Biochemistry and Cell Biology, MD Anderson Cancer Center and University of Texas Health Sciences Center Graduate School of Biomedical Sciences, Houston, TX, 77030
- Graduate Program in Neuroscience, MD Anderson Cancer Center and University of Texas Health Sciences Center Graduate School of Biomedical Sciences, Houston, TX, 77030
| | - Ching-On Wong
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| |
Collapse
|
5
|
Cozzi M, Ferrari V. Autophagy Dysfunction in ALS: from Transport to Protein Degradation. J Mol Neurosci 2022; 72:1456-1481. [PMID: 35708843 PMCID: PMC9293831 DOI: 10.1007/s12031-022-02029-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/17/2022] [Indexed: 01/18/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting upper and lower motor neurons (MNs). Since the identification of the first ALS mutation in 1993, more than 40 genes have been associated with the disorder. The most frequent genetic causes of ALS are represented by mutated genes whose products challenge proteostasis, becoming unable to properly fold and consequently aggregating into inclusions that impose proteotoxic stress on affected cells. In this context, increasing evidence supports the central role played by autophagy dysfunctions in the pathogenesis of ALS. Indeed, in early stages of disease, high levels of proteins involved in autophagy are present in ALS MNs; but at the same time, with neurodegeneration progression, autophagy-mediated degradation decreases, often as a result of the accumulation of toxic protein aggregates in affected cells. Autophagy is a complex multistep pathway that has a central role in maintaining cellular homeostasis. Several proteins are involved in its tight regulation, and importantly a relevant fraction of ALS-related genes encodes products that directly take part in autophagy, further underlining the relevance of this key protein degradation system in disease onset and progression. In this review, we report the most relevant findings concerning ALS genes whose products are involved in the several steps of the autophagic pathway, from phagophore formation to autophagosome maturation and transport and finally to substrate degradation.
Collapse
Affiliation(s)
- Marta Cozzi
- Dipartimento Di Scienze Farmacologiche E Biomolecolari, Università Degli Studi Di Milano, 20133, Milan, Italy.
| | - Veronica Ferrari
- Dipartimento Di Scienze Farmacologiche E Biomolecolari, Università Degli Studi Di Milano, 20133, Milan, Italy.
| |
Collapse
|
6
|
Fenckova M, Muha V, Mariappa D, Catinozzi M, Czajewski I, Blok LER, Ferenbach AT, Storkebaum E, Schenck A, van Aalten DMF. Intellectual disability-associated disruption of O-GlcNAc cycling impairs habituation learning in Drosophila. PLoS Genet 2022; 18:e1010159. [PMID: 35500025 PMCID: PMC9140282 DOI: 10.1371/journal.pgen.1010159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 05/27/2022] [Accepted: 03/21/2022] [Indexed: 11/19/2022] Open
Abstract
O-GlcNAcylation is a reversible co-/post-translational modification involved in a multitude of cellular processes. The addition and removal of the O-GlcNAc modification is controlled by two conserved enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (OGA). Mutations in OGT have recently been discovered to cause a novel Congenital Disorder of Glycosylation (OGT-CDG) that is characterized by intellectual disability. The mechanisms by which OGT-CDG mutations affect cognition remain unclear. We manipulated O-GlcNAc transferase and O-GlcNAc hydrolase activity in Drosophila and demonstrate an important role of O-GlcNAcylation in habituation learning and synaptic development at the larval neuromuscular junction. Introduction of patient-specific missense mutations into Drosophila O-GlcNAc transferase using CRISPR/Cas9 gene editing leads to deficits in locomotor function and habituation learning. The habituation deficit can be corrected by blocking O-GlcNAc hydrolysis, indicating that OGT-CDG mutations affect cognition-relevant habituation via reduced protein O-GlcNAcylation. This study establishes a critical role for O-GlcNAc cycling and disrupted O-GlcNAc transferase activity in cognitive dysfunction, and suggests that blocking O-GlcNAc hydrolysis is a potential strategy to treat OGT-CDG.
Collapse
Affiliation(s)
- Michaela Fenckova
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Villo Muha
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Daniel Mariappa
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Marica Catinozzi
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Ignacy Czajewski
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Laura E. R. Blok
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Andrew T. Ferenbach
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Erik Storkebaum
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Daan M. F. van Aalten
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| |
Collapse
|
7
|
Kors S, Costello JL, Schrader M. VAP Proteins - From Organelle Tethers to Pathogenic Host Interactors and Their Role in Neuronal Disease. Front Cell Dev Biol 2022; 10:895856. [PMID: 35756994 PMCID: PMC9213790 DOI: 10.3389/fcell.2022.895856] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 04/25/2022] [Indexed: 12/26/2022] Open
Abstract
Vesicle-associated membrane protein (VAMP)-associated proteins (VAPs) are ubiquitous ER-resident tail-anchored membrane proteins in eukaryotic cells. Their N-terminal major sperm protein (MSP) domain faces the cytosol and allows them to interact with a wide variety of cellular proteins. Therefore, VAP proteins are vital to many cellular processes, including organelle membrane tethering, lipid transfer, autophagy, ion homeostasis and viral defence. Here, we provide a timely overview of the increasing number of VAPA/B binding partners and discuss the role of VAPA/B in maintaining organelle-ER interactions and cooperation. Furthermore, we address how viruses and intracellular bacteria hijack VAPs and their binding partners to induce interactions between the host ER and pathogen-containing compartments and support pathogen replication. Finally, we focus on the role of VAP in human disease and discuss how mutated VAPB leads to the disruption of cellular homeostasis and causes amyotrophic lateral sclerosis.
Collapse
Affiliation(s)
- Suzan Kors
- *Correspondence: Suzan Kors, ; Michael Schrader,
| | | | | |
Collapse
|
8
|
Borgese N, Iacomino N, Colombo SF, Navone F. The Link between VAPB Loss of Function and Amyotrophic Lateral Sclerosis. Cells 2021; 10:1865. [PMID: 34440634 PMCID: PMC8392409 DOI: 10.3390/cells10081865] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 02/06/2023] Open
Abstract
The VAP proteins are integral adaptor proteins of the endoplasmic reticulum (ER) membrane that recruit a myriad of interacting partners to the ER surface. Through these interactions, the VAPs mediate a large number of processes, notably the generation of membrane contact sites between the ER and essentially all other cellular membranes. In 2004, it was discovered that a mutation (p.P56S) in the VAPB paralogue causes a rare form of dominantly inherited familial amyotrophic lateral sclerosis (ALS8). The mutant protein is aggregation-prone, non-functional and unstable, and its expression from a single allele appears to be insufficient to support toxic gain-of-function effects within motor neurons. Instead, loss-of-function of the single wild-type allele is required for pathological effects, and VAPB haploinsufficiency may be the main driver of the disease. In this article, we review the studies on the effects of VAPB deficit in cellular and animal models. Several basic cell physiological processes are affected by downregulation or complete depletion of VAPB, impinging on phosphoinositide homeostasis, Ca2+ signalling, ion transport, neurite extension, and ER stress. In the future, the distinction between the roles of the two VAP paralogues (A and B), as well as studies on motor neurons generated from induced pluripotent stem cells (iPSC) of ALS8 patients will further elucidate the pathogenic basis of p.P56S familial ALS, as well as of other more common forms of the disease.
Collapse
Affiliation(s)
- Nica Borgese
- CNR Institute of Neuroscience, Via Follereau 3, Bldg U28, 20854 Vedano al Lambro, Italy; (N.I.); (S.F.C.)
| | | | | | - Francesca Navone
- CNR Institute of Neuroscience, Via Follereau 3, Bldg U28, 20854 Vedano al Lambro, Italy; (N.I.); (S.F.C.)
| |
Collapse
|
9
|
Borgese N, Navone F, Nukina N, Yamanaka T. Mutant VAPB: Culprit or Innocent Bystander of Amyotrophic Lateral Sclerosis? CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:25152564211022515. [PMID: 37366377 PMCID: PMC10243577 DOI: 10.1177/25152564211022515] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/08/2021] [Accepted: 05/12/2021] [Indexed: 06/28/2023]
Abstract
Nearly twenty years ago a mutation in the VAPB gene, resulting in a proline to serine substitution (p.P56S), was identified as the cause of a rare, slowly progressing, familial form of the motor neuron degenerative disease Amyotrophic Lateral Sclerosis (ALS). Since then, progress in unravelling the mechanistic basis of this mutation has proceeded in parallel with research on the VAP proteins and on their role in establishing membrane contact sites between the ER and other organelles. Analysis of the literature on cellular and animal models reviewed here supports the conclusion that P56S-VAPB, which is aggregation-prone, non-functional and unstable, is expressed at levels that are insufficient to support toxic gain-of-function or dominant negative effects within motor neurons. Instead, insufficient levels of the product of the single wild-type allele appear to be required for pathological effects, and may be the main driver of the disease. In light of the multiple interactions of the VAP proteins, we address the consequences of specific VAPB depletion and highlight various affected processes that could contribute to motor neuron degeneration. In the future, distinction of specific roles of each of the two VAP paralogues should help to further elucidate the basis of p.P56S familial ALS, as well as of other more common forms of the disease.
Collapse
Affiliation(s)
- Nica Borgese
- CNR Institute of
Neuroscience, Vedano al Lambro (MB), Italy
| | | | - Nobuyuki Nukina
- Laboratory of Structural
Neuropathology, Doshisha University Graduate School of Brain Science,
Kyoto, Japan
| | - Tomoyuki Yamanaka
- Laboratory of Structural
Neuropathology, Doshisha University Graduate School of Brain Science,
Kyoto, Japan
| |
Collapse
|
10
|
Beaver M, Bhatnagar A, Panikker P, Zhang H, Snook R, Parmar V, Vijayakumar G, Betini N, Akhter S, Elefant F. Disruption of Tip60 HAT mediated neural histone acetylation homeostasis is an early common event in neurodegenerative diseases. Sci Rep 2020; 10:18265. [PMID: 33106538 PMCID: PMC7588445 DOI: 10.1038/s41598-020-75035-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 10/05/2020] [Indexed: 12/12/2022] Open
Abstract
Epigenetic dysregulation is a common mechanism shared by molecularly and clinically heterogenous neurodegenerative diseases (NDs). Histone acetylation homeostasis, maintained by the antagonistic activity of histone acetyltransferases (HATs) and histone deacetylases (HDACs), is necessary for appropriate gene expression and neuronal function. Disruption of neural acetylation homeostasis has been implicated in multiple types of NDs including Alzheimer's disease (AD), yet mechanisms underlying alterations remain unclear. We show that like AD, disruption of Tip60 HAT/HDAC2 balance with concomitant epigenetic repression of common Tip60 target neuroplasticity genes occurs early in multiple types of Drosophila ND models such as Parkinson's Disease (PD), Huntington's Disease (HD) and Amyotrophic Lateral Sclerosis (ALS). Repressed neuroplasticity genes show reduced enrichment of Tip60 and epigentic acetylation signatures at all gene loci examined with certain genes showing inappropriate HDAC2 repressor enrichment. Functional neuronal consequences for these disease conditions are reminiscent of human pathology and include locomotion, synapse morphology, and short-term memory deficits. Increasing Tip60 HAT levels specifically in the mushroom body learning and memory center in the Drosophila brain protects against locomotion and short-term memory function deficits in multiple NDs. Together, our results support a model by which Tip60 protects against neurological impairments in different NDs via similar modes of action.
Collapse
Affiliation(s)
- Mariah Beaver
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Akanksha Bhatnagar
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Priyalakshmi Panikker
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Haolin Zhang
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Renee Snook
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Visha Parmar
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Gayathri Vijayakumar
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Niteesha Betini
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Sunya Akhter
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA
| | - Felice Elefant
- Department of Biology, Drexel University, 3245 Chestnut Street, PISB 312, Philadelphia, PA, 19104, USA.
| |
Collapse
|
11
|
Teixeira V, Maciel P, Costa V. Leading the way in the nervous system: Lipid Droplets as new players in health and disease. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1866:158820. [PMID: 33010453 DOI: 10.1016/j.bbalip.2020.158820] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/01/2020] [Accepted: 09/21/2020] [Indexed: 12/28/2022]
Abstract
Lipid droplets (LDs) are ubiquitous fat storage organelles composed of a neutral lipid core, comprising triacylglycerols (TAG) and sterol esters (SEs), surrounded by a phospholipid monolayer membrane with several decorating proteins. Recently, LD biology has come to the foreground of research due to their importance for energy homeostasis and cellular stress response. As aberrant LD accumulation and lipid depletion are hallmarks of numerous diseases, addressing LD biogenesis and turnover provides a new framework for understanding disease-related mechanisms. Here we discuss the potential role of LDs in neurodegeneration, while making some predictions on how LD imbalance can contribute to pathophysiology in the brain.
Collapse
Affiliation(s)
- Vitor Teixeira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Vítor Costa
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| |
Collapse
|
12
|
Mejzini R, Flynn LL, Pitout IL, Fletcher S, Wilton SD, Akkari PA. ALS Genetics, Mechanisms, and Therapeutics: Where Are We Now? Front Neurosci 2019; 13:1310. [PMID: 31866818 PMCID: PMC6909825 DOI: 10.3389/fnins.2019.01310] [Citation(s) in RCA: 435] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/22/2019] [Indexed: 12/11/2022] Open
Abstract
The scientific landscape surrounding amyotrophic lateral sclerosis (ALS) continues to shift as the number of genes associated with the disease risk and pathogenesis, and the cellular processes involved, continues to grow. Despite decades of intense research and over 50 potentially causative or disease-modifying genes identified, etiology remains unexplained and treatment options remain limited for the majority of ALS patients. Various factors have contributed to the slow progress in understanding and developing therapeutics for this disease. Here, we review the genetic basis of ALS, highlighting factors that have contributed to the elusiveness of genetic heritability. The most commonly mutated ALS-linked genes are reviewed with an emphasis on disease-causing mechanisms. The cellular processes involved in ALS pathogenesis are discussed, with evidence implicating their involvement in ALS summarized. Past and present therapeutic strategies and the benefits and limitations of the model systems available to ALS researchers are discussed with future directions for research that may lead to effective treatment strategies outlined.
Collapse
Affiliation(s)
- Rita Mejzini
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
| | - Loren L. Flynn
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - Ianthe L. Pitout
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - P. Anthony Akkari
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| |
Collapse
|
13
|
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating, uniformly lethal degenerative disorder of motor neurons that overlaps clinically with frontotemporal dementia (FTD). Investigations of the 10% of ALS cases that are transmitted as dominant traits have revealed numerous gene mutations and variants that either cause these disorders or influence their clinical phenotype. The evolving understanding of the genetic architecture of ALS has illuminated broad themes in the molecular pathophysiology of both familial and sporadic ALS and FTD. These central themes encompass disturbances of protein homeostasis, alterations in the biology of RNA binding proteins, and defects in cytoskeletal dynamics, as well as numerous downstream pathophysiological events. Together, these findings from ALS genetics provide new insight into therapies that target genetically distinct subsets of ALS and FTD.
Collapse
Affiliation(s)
- Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| |
Collapse
|
14
|
Hauswirth AG, Ford KJ, Wang T, Fetter RD, Tong A, Davis GW. A postsynaptic PI3K-cII dependent signaling controller for presynaptic homeostatic plasticity. eLife 2018; 7:31535. [PMID: 29303480 PMCID: PMC5773188 DOI: 10.7554/elife.31535] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/04/2018] [Indexed: 01/29/2023] Open
Abstract
Presynaptic homeostatic plasticity stabilizes information transfer at synaptic connections in organisms ranging from insect to human. By analogy with principles of engineering and control theory, the molecular implementation of PHP is thought to require postsynaptic signaling modules that encode homeostatic sensors, a set point, and a controller that regulates transsynaptic negative feedback. The molecular basis for these postsynaptic, homeostatic signaling elements remains unknown. Here, an electrophysiology-based screen of the Drosophila kinome and phosphatome defines a postsynaptic signaling platform that includes a required function for PI3K-cII, PI3K-cIII and the small GTPase Rab11 during the rapid and sustained expression of PHP. We present evidence that PI3K-cII localizes to Golgi-derived, clathrin-positive vesicles and is necessary to generate an endosomal pool of PI(3)P that recruits Rab11 to recycling endosomal membranes. A morphologically distinct subdivision of this platform concentrates postsynaptically where we propose it functions as a homeostatic controller for retrograde, trans-synaptic signaling.
Collapse
Affiliation(s)
- Anna G Hauswirth
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Kevin J Ford
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Tingting Wang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Richard D Fetter
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Amy Tong
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Graeme W Davis
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| |
Collapse
|
15
|
Azuma Y, Mizuta I, Tokuda T, Mizuno T. Amyotrophic Lateral Sclerosis Model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1076:79-95. [PMID: 29951816 DOI: 10.1007/978-981-13-0529-0_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects upper and lower motor neurons in the brain and the spinal cord. Due to the progressive neurodegeneration, ALS leads to paralysis and death caused by respiratory failure 2-5 years after the onset of symptoms. There is no effective cure available. Most ALS cases are sporadic, without family history, whereas 10% of the cases are familial. Identification of variants in more than 30 different loci has provided insight into the pathogenic molecular mechanisms mediating disease pathogenesis. Studies of a Drosophila melanogaster model for each of the ALS genes can contribute to uncovering pathophysiological mechanism of ALS and finding targets of the disease-modifying therapy. In this review, we focus on three ALS-causing genes: TAR DNA-binding protein (TDP-43), fused in sarcoma/translocated in liposarcoma (FUS/TLS), and chromosome 9 open reading frame 72 (C9orf72).
Collapse
Affiliation(s)
- Yumiko Azuma
- Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
| | - Ikuko Mizuta
- Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Takahiko Tokuda
- Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Molecular Pathobiology of Brain Diseases, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Toshiki Mizuno
- Department of Neurology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| |
Collapse
|
16
|
Shahheydari H, Ragagnin A, Walker AK, Toth RP, Vidal M, Jagaraj CJ, Perri ER, Konopka A, Sultana JM, Atkin JD. Protein Quality Control and the Amyotrophic Lateral Sclerosis/Frontotemporal Dementia Continuum. Front Mol Neurosci 2017; 10:119. [PMID: 28539871 PMCID: PMC5423993 DOI: 10.3389/fnmol.2017.00119] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis, or proteostasis, has an important regulatory role in cellular function. Protein quality control mechanisms, including protein folding and protein degradation processes, have a crucial function in post-mitotic neurons. Cellular protein quality control relies on multiple strategies, including molecular chaperones, autophagy, the ubiquitin proteasome system, endoplasmic reticulum (ER)-associated degradation (ERAD) and the formation of stress granules (SGs), to regulate proteostasis. Neurodegenerative diseases are characterized by the presence of misfolded protein aggregates, implying that protein quality control mechanisms are dysfunctional in these conditions. Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that are now recognized to overlap clinically and pathologically, forming a continuous disease spectrum. In this review article, we detail the evidence for dysregulation of protein quality control mechanisms across the whole ALS-FTD continuum, by discussing the major proteins implicated in ALS and/or FTD. We also discuss possible ways in which protein quality mechanisms could be targeted therapeutically in these disorders and highlight promising protein quality control-based therapeutics for clinical trials.
Collapse
Affiliation(s)
- Hamideh Shahheydari
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Audrey Ragagnin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Adam K Walker
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Reka P Toth
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Marta Vidal
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Cyril J Jagaraj
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Emma R Perri
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Anna Konopka
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Jessica M Sultana
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Julie D Atkin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia.,Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe UniversityMelbourne, VIC, Australia
| |
Collapse
|
17
|
Kudo A, Shigenobu S, Kadota K, Nozawa M, Shibata TF, Ishikawa Y, Matsuo T. Comparative analysis of the brain transcriptome in a hyper-aggressive fruit fly, Drosophila prolongata. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 82:11-20. [PMID: 28115271 DOI: 10.1016/j.ibmb.2017.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 01/16/2017] [Accepted: 01/17/2017] [Indexed: 06/06/2023]
Abstract
Aggressive behavior is observed in many animals, but its intensity differs between species. In a model animal of genetics, Drosophila melanogaster, genetic basis of aggressive behavior has been studied intensively, including transcriptome analyses to identify genes whose expression level was associated with intra-species variation in aggressiveness. However, whether these genes are also involved in the evolution of aggressiveness among different species has not been examined. In this study, we performed de novo transcriptome analysis in the brain of Drosophila prolongata to identify genes associated with the evolution of aggressiveness. Males of D. prolongata were hyper-aggressive compared with closely related species. Comparison of the brain transcriptomes identified 21 differentially expressed genes in males of D. prolongata. They did not overlap with the list of aggression-related genes identified in D. melanogaster, suggesting that genes involved in the evolution of aggressiveness were independent of those associated with the intra-species variation in aggressiveness in Drosophila. Although females of D. prolongata were not aggressive as the males, expression levels of the 21 genes identified in this study were more similar between sexes than between species.
Collapse
Affiliation(s)
- Ayumi Kudo
- Department of Agricultural and Environmental Biology, The University of Tokyo, Tokyo, Japan
| | - Shuji Shigenobu
- National Institute for Basic Biology, Okazaki, Japan; Department of Basic Biology, Faculty of Life Science, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Koji Kadota
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | | | | | - Yukio Ishikawa
- Department of Agricultural and Environmental Biology, The University of Tokyo, Tokyo, Japan
| | - Takashi Matsuo
- Department of Agricultural and Environmental Biology, The University of Tokyo, Tokyo, Japan.
| |
Collapse
|
18
|
Jesse CM, Bushuven E, Tripathi P, Chandrasekar A, Simon CM, Drepper C, Yamoah A, Dreser A, Katona I, Johann S, Beyer C, Wagner S, Grond M, Nikolin S, Anink J, Troost D, Sendtner M, Goswami A, Weis J. ALS-Associated Endoplasmic Reticulum Proteins in Denervated Skeletal Muscle: Implications for Motor Neuron Disease Pathology. Brain Pathol 2017; 27:781-794. [PMID: 27790792 DOI: 10.1111/bpa.12453] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 10/25/2016] [Indexed: 12/14/2022] Open
Abstract
Alpha-motoneurons and muscle fibres are structurally and functionally interdependent. Both cell types particularly rely on endoplasmic reticulum (ER/SR) functions. Mutations of the ER proteins VAPB, SigR1 and HSP27 lead to hereditary motor neuron diseases (MNDs). Here, we determined the expression profile and localization of these ER proteins/chaperons by immunohistochemistry and immunoblotting in biopsy and autopsy muscle tissue of patients with amyotrophic lateral sclerosis (ALS) and other neurogenic muscular atrophies (NMAs) and compared these patterns to mouse models of neurogenic muscular atrophy. Postsynaptic neuromuscular junction staining for VAPB was intense in normal human and mouse muscle and decreased in denervated Nmd2J mouse muscle fibres. In contrast, VAPB levels together with other chaperones and autophagy markers were increased in extrasynaptic regions of denervated muscle fibres of patients with MNDs and other NMAs, especially at sites of focal myofibrillar disintegration (targets). These findings did not differ between NMAs due to ALS and other causes. G93A-SOD1 mouse muscle fibres showed a similar pattern of protein level increases in denervated muscle fibres. In addition, they showed globular VAPB-immunoreactive structures together with misfolded SOD1 protein accumulations, suggesting a primary myopathic change. Our findings indicate that altered expression and localization of these ER proteins and autophagy markers are part of the dynamic response of muscle fibres to denervation. The ER is particularly prominent and vulnerable in both muscle fibres and alpha-motoneurons. Thus, ER pathology could contribute to the selective build-up of degenerative changes in the neuromuscular axis in MNDs.
Collapse
Affiliation(s)
- C M Jesse
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany.,Department of Neurosurgery, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - E Bushuven
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - P Tripathi
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - A Chandrasekar
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany.,Department of Neurology, Ulm University, Helmholtzstr 8/2, Ulm, 89081, Germany
| | - C M Simon
- Institute of Clinical Neurobiology, University of Würzburg, Versbacherstr. 5, Würzburg, 97078, Germany.,Columbia University Medical Center, Center for Motor Neuron Biology and Disease, 630 West 168th Street, New York, NY, 10032
| | - C Drepper
- Institute of Clinical Neurobiology, University of Würzburg, Versbacherstr. 5, Würzburg, 97078, Germany.,Department of Child and Adolescent Psychiatry, University Hospital Würzburg, Füchsleinstr. 15, Würzburg, 97080, Germany
| | - A Yamoah
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - A Dreser
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - I Katona
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - S Johann
- Institute of Neuroanatomy, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - C Beyer
- Institute of Neuroanatomy, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - S Wagner
- Department of Neurology, District Hospital Siegen, Siegen, 57076, Germany
| | - M Grond
- Department of Neurology, District Hospital Siegen, Siegen, 57076, Germany
| | - S Nikolin
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - J Anink
- Academic Medical Centre, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands
| | - D Troost
- Academic Medical Centre, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands
| | - M Sendtner
- Institute of Clinical Neurobiology, University of Würzburg, Versbacherstr. 5, Würzburg, 97078, Germany
| | - A Goswami
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| | - J Weis
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074 Aachen, Germany
| |
Collapse
|
19
|
Amyotrophic Lateral Sclerosis Pathogenesis Converges on Defects in Protein Homeostasis Associated with TDP-43 Mislocalization and Proteasome-Mediated Degradation Overload. Curr Top Dev Biol 2017; 121:111-171. [DOI: 10.1016/bs.ctdb.2016.07.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
20
|
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease causing the death of motor neurons with consequent muscle atrophy and paralysis. Several neurodegenerative diseases have been modeled in Drosophila and genetic studies on this model organism led to the elucidation of crucial aspects of disease mechanisms. ALS, however, has lagged somewhat behind possibly because of the lack of a suitable genetic model. We were the first to develop a fly model for ALS and over the last few years, we have implemented and used this model for a large scale, unbiased modifier screen. We also report an extensive bioinformatic analysis of the genetic modifiers and we show that most of them are associated in a network of interacting genes controlling known as well as novel cellular processes involved in ALS pathogenesis. A similar analysis for the human homologues of the Drosophila modifiers and the validation of a subset of them in human tissues confirm and expand the significance of the data for the human disease. Finally, we analyze a possible application of the model in the process of therapeutic discovery in ALS and we discuss the importance of novel “non-obvious” models for the disease.
Collapse
Affiliation(s)
- Andrea Chai
- a Euan McDonald Center for Motor Neurone Disease Research.,b Centre for Integrative Physiology; University of Edinburgh ; Edinburgh ; UK
| | - Giuseppa Pennetta
- a Euan McDonald Center for Motor Neurone Disease Research.,b Centre for Integrative Physiology; University of Edinburgh ; Edinburgh ; UK
| |
Collapse
|
21
|
Sanhueza M, Kubasik-Thayil A, Pennetta G. Why Quantification Matters: Characterization of Phenotypes at the Drosophila Larval Neuromuscular Junction. J Vis Exp 2016. [PMID: 27213489 PMCID: PMC4942095 DOI: 10.3791/53821] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Most studies on morphogenesis rely on qualitative descriptions of how anatomical traits are affected by the disruption of specific genes and genetic pathways. Quantitative descriptions are rarely performed, although genetic manipulations produce a range of phenotypic effects and variations are observed even among individuals within control groups. Emerging evidence shows that morphology, size and location of organelles play a previously underappreciated, yet fundamental role in cell function and survival. Here we provide step-by-step instructions for performing quantitative analyses of phenotypes at the Drosophila larval neuromuscular junction (NMJ). We use several reliable immuno-histochemical markers combined with bio-imaging techniques and morphometric analyses to examine the effects of genetic mutations on specific cellular processes. In particular, we focus on the quantitative analysis of phenotypes affecting morphology, size and position of nuclei within the striated muscles of Drosophila larvae. The Drosophila larval NMJ is a valuable experimental model to investigate the molecular mechanisms underlying the structure and the function of the neuromuscular system, both in health and disease. However, the methodologies we describe here can be extended to other systems as well.
Collapse
Affiliation(s)
- Mario Sanhueza
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh
| | | | - Giuseppa Pennetta
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh;
| |
Collapse
|
22
|
Krieger C, Wang SJH, Yoo SH, Harden N. Adducin at the Neuromuscular Junction in Amyotrophic Lateral Sclerosis: Hanging on for Dear Life. Front Cell Neurosci 2016; 10:11. [PMID: 26858605 PMCID: PMC4731495 DOI: 10.3389/fncel.2016.00011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 01/13/2016] [Indexed: 12/11/2022] Open
Abstract
The neurological dysfunction in amyotrophic lateral sclerosis (ALS)/motor neurone disease (MND) is associated with defective nerve-muscle contacts early in the disease suggesting that perturbations of cell adhesion molecules (CAMs) linking the pre- and post-synaptic components of the neuromuscular junction (NMJ) are involved. To search for candidate proteins implicated in this degenerative process, researchers have studied the Drosophila larval NMJ and find that the cytoskeleton-associated protein, adducin, is ideally placed to regulate synaptic contacts. By controlling the levels of synaptic proteins, adducin can de-stabilize synaptic contacts. Interestingly, elevated levels of phosphorylated adducin have been reported in ALS patients and in a mouse model of the disease. Adducin is regulated by phosphorylation through protein kinase C (PKC), some isoforms of which exhibit Ca2+-dependence, raising the possibility that changes in intracellular Ca2+ might alter PKC activation and secondarily influence adducin phosphorylation. Furthermore, adducin has interactions with the alpha subunit of the Na+/K+-ATPase. Thus, the phosphorylation of adducin may secondarily influence synaptic stability at the NMJ and so influence pre- and post-synaptic integrity at the NMJ in ALS.
Collapse
Affiliation(s)
- Charles Krieger
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University Burnaby, BC, Canada
| | - Simon Ji Hau Wang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser UniversityBurnaby, BC, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser UniversityBurnaby, BC, Canada
| | - Soo Hyun Yoo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser UniversityBurnaby, BC, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser UniversityBurnaby, BC, Canada
| | - Nicholas Harden
- Department of Molecular Biology and Biochemistry, Simon Fraser University Burnaby, BC, Canada
| |
Collapse
|
23
|
Ernst WL, Shome K, Wu CC, Gong X, Frizzell RA, Aridor M. VAMP-associated Proteins (VAP) as Receptors That Couple Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Proteostasis with Lipid Homeostasis. J Biol Chem 2016; 291:5206-20. [PMID: 26740627 DOI: 10.1074/jbc.m115.692749] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Indexed: 12/27/2022] Open
Abstract
Unesterified cholesterol accumulates in late endosomes in cells expressing the misfolded cystic fibrosis transmembrane conductance regulator (CFTR). CFTR misfolding in the endoplasmic reticulum (ER) or general activation of ER stress led to dynein-mediated clustering of cholesterol-loaded late endosomes at the Golgi region, a process regulated by ER-localized VAMP-associated proteins (VAPs). We hypothesized that VAPs serve as intracellular receptors that couple lipid homeostasis through interactions with two phenylalanines in an acidic track (FFAT) binding signals (found in lipid sorting and sensing proteins, LSS) with proteostasis regulation. VAPB inhibited the degradation of ΔF508-CFTR. The activity was mapped to the ligand-binding major sperm protein (MSP) domain, which was sufficient in regulating CFTR biogenesis. We identified mutations in an unstructured loop within the MSP that uncoupled VAPB-regulated CFTR biogenesis from basic interactions with FFAT. Using this information, we defined functional and physical interactions between VAPB and proteostasis regulators (ligands), including the unfolded protein response sensor ATF6 and the ER degradation cluster that included FAF1, VCP, BAP31, and Derlin-1. VAPB inhibited the degradation of ΔF508-CFTR in the ER through interactions with the RMA1-Derlin-BAP31-VCP pathway. Analysis of pseudoligands containing tandem FFAT signals supports a competitive model for VAP interactions that direct CFTR biogenesis. The results suggest a model in which VAP-ligand binding couples proteostasis and lipid homeostasis leading to observed phenotypes of lipid abnormalities in protein folding diseases.
Collapse
Affiliation(s)
- Wayne L Ernst
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Kuntala Shome
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Christine C Wu
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Xiaoyan Gong
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Raymond A Frizzell
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Meir Aridor
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| |
Collapse
|
24
|
Kun-Rodrigues C, Ganos C, Guerreiro R, Schneider SA, Schulte C, Lesage S, Darwent L, Holmans P, Singleton A, Bhatia K, Bras J. A systematic screening to identify de novo mutations causing sporadic early-onset Parkinson's disease. Hum Mol Genet 2015; 24:6711-20. [PMID: 26362251 PMCID: PMC4634375 DOI: 10.1093/hmg/ddv376] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/08/2015] [Indexed: 12/13/2022] Open
Abstract
Despite the many advances in our understanding of the genetic basis of Mendelian forms of Parkinson's disease (PD), a large number of early-onset cases still remain to be explained. Many of these cases, present with a form of disease that is identical to that underlined by genetic causes, but do not have mutations in any of the currently known disease-causing genes. Here, we hypothesized that de novo mutations may account for a proportion of these early-onset, sporadic cases. We performed exome sequencing in full parent–child trios where the proband presents with typical PD to unequivocally identify de novo mutations. This approach allows us to test all genes in the genome in an unbiased manner. We have identified and confirmed 20 coding de novo mutations in 21 trios. We have used publicly available population genetic data to compare variant frequencies and our independent in-house dataset of exome sequencing in PD (with over 1200 cases) to identify additional variants in the same genes. Of the genes identified to carry de novo mutations, PTEN, VAPB and ASNA1 are supported by various sources of data to be involved in PD. We show that these genes are reported to be within a protein–protein interaction network with PD genes and that they contain additional rare, case-specific, mutations in our independent cohort of PD cases. Our results support the involvement of these three genes in PD and suggest that testing for de novo mutations in sporadic disease may aid in the identification of novel disease-causing genes.
Collapse
Affiliation(s)
- Celia Kun-Rodrigues
- Department of Molecular Neuroscience, UCL Institute of Neurology, London WC1N 3AR, UK
| | - Christos Ganos
- Department of Neurology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg 20246, Germany, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Rita Guerreiro
- Department of Molecular Neuroscience, UCL Institute of Neurology, London WC1N 3AR, UK
| | - Susanne A Schneider
- Department of Neurology, University Hospital Schleswig Holstein, Campus Kiel 24105, Germany
| | - Claudia Schulte
- German Center for Neurodegenerative Diseases, Tübingen, Germany, Department of Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen 72076, Germany
| | - Suzanne Lesage
- INSERM U M27, Pitié-Salpêtrière Hospital, Brain and Spinal Cord Institute (ICM), Paris 75013, France
| | - Lee Darwent
- Department of Molecular Neuroscience, UCL Institute of Neurology, London WC1N 3AR, UK
| | - Peter Holmans
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF24 4HQ, UK and
| | - Andrew Singleton
- Laboratory of Neurogenetics, National Institutes on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kailash Bhatia
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Jose Bras
- Department of Molecular Neuroscience, UCL Institute of Neurology, London WC1N 3AR, UK,
| |
Collapse
|
25
|
Autophagy and Neurodegeneration: Insights from a Cultured Cell Model of ALS. Cells 2015; 4:354-86. [PMID: 26287246 PMCID: PMC4588041 DOI: 10.3390/cells4030354] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 07/07/2015] [Accepted: 07/27/2015] [Indexed: 12/11/2022] Open
Abstract
Autophagy plays a major role in the elimination of cellular waste components, the renewal of intracellular proteins and the prevention of the build-up of redundant or defective material. It is fundamental for the maintenance of homeostasis and especially important in post-mitotic neuronal cells, which, without competent autophagy, accumulate protein aggregates and degenerate. Many neurodegenerative diseases are associated with defective autophagy; however, whether altered protein turnover or accumulation of misfolded, aggregate-prone proteins is the primary insult in neurodegeneration has long been a matter of debate. Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by selective degeneration of motor neurons. Most of the ALS cases occur in sporadic forms (SALS), while 10%–15% of the cases have a positive familial history (FALS). The accumulation in the cell of misfolded/abnormal proteins is a hallmark of both SALS and FALS, and altered protein degradation due to autophagy dysregulation has been proposed to contribute to ALS pathogenesis. In this review, we focus on the main molecular features of autophagy to provide a framework for discussion of our recent findings about the role in disease pathogenesis of the ALS-linked form of the VAPB gene product, a mutant protein that drives the generation of unusual cytoplasmic inclusions.
Collapse
|
26
|
Sanhueza M, Chai A, Smith C, McCray BA, Simpson TI, Taylor JP, Pennetta G. Network analyses reveal novel aspects of ALS pathogenesis. PLoS Genet 2015; 11:e1005107. [PMID: 25826266 PMCID: PMC4380362 DOI: 10.1371/journal.pgen.1005107] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 02/27/2015] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by selective loss of motor neurons, muscle atrophy and paralysis. Mutations in the human VAMP-associated protein B (hVAPB) cause a heterogeneous group of motor neuron diseases including ALS8. Despite extensive research, the molecular mechanisms underlying ALS pathogenesis remain largely unknown. Genetic screens for key interactors of hVAPB activity in the intact nervous system, however, represent a fundamental approach towards understanding the in vivo function of hVAPB and its role in ALS pathogenesis. Targeted expression of the disease-causing allele leads to neurodegeneration and progressive decline in motor performance when expressed in the adult Drosophila, eye or in its entire nervous system, respectively. By using these two phenotypic readouts, we carried out a systematic survey of the Drosophila genome to identify modifiers of hVAPB-induced neurotoxicity. Modifiers cluster in a diverse array of biological functions including processes and genes that have been previously linked to hVAPB function, such as proteolysis and vesicular trafficking. In addition to established mechanisms, the screen identified endocytic trafficking and genes controlling proliferation and apoptosis as potent modifiers of ALS8-mediated defects. Surprisingly, the list of modifiers was mostly enriched for proteins linked to lipid droplet biogenesis and dynamics. Computational analysis reveals that most modifiers can be linked into a complex network of interacting genes, and that the human genes homologous to the Drosophila modifiers can be assembled into an interacting network largely overlapping with that in flies. Identity markers of the endocytic process were also found to abnormally accumulate in ALS patients, further supporting the relevance of the fly data for human biology. Collectively, these results not only lead to a better understanding of hVAPB function but also point to potentially relevant targets for therapeutic intervention. Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease causing loss of motor neurons and consequently a progressive deterioration of motor functions. ALS is uniformly fatal with death occurring 5 years after onset of symptoms. There is currently no effective treatment for ALS. Several mutations in a gene called hVAPB have shown that this gene is causative of a type of ALS known as ALS8. In this study we sought to identify genes and cellular processes that are involved in the toxicity conferred by the defective ALS8 allele. By using the power of Drosophila genetics, we performed a large scale genomic screen and identified a number of genes that can affect hVAPB-mediated toxicity. These modifiers cluster into functional pathways known to be involved in ALS as well as novel ones. The relevance of these modifiers and mechanisms for the human disease was confirmed by showing that the human homologues of the fly modifiers can be organized into a network that closely resembles that of the Drosophila genes. Identifying cellular processes and proteins that modulate hVAPB pathological activity can facilitate the discovery of an effective treatment for ALS.
Collapse
Affiliation(s)
- Mario Sanhueza
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrea Chai
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Houston, Texas, United States of America
| | - Colin Smith
- Academic Department of Neuropathology, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Brett A. McCray
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Cambridge, Massachusetts, United States of America
| | - T. Ian Simpson
- Biomathematics and Statistics Scotland, University of Edinburgh, United Kingdom
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, United Kingdom
| | - J. Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Giuseppa Pennetta
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
| |
Collapse
|
27
|
Lattante S, de Calbiac H, Le Ber I, Brice A, Ciura S, Kabashi E. Sqstm1 knock-down causes a locomotor phenotype ameliorated by rapamycin in a zebrafish model of ALS/FTLD. Hum Mol Genet 2014; 24:1682-90. [PMID: 25410659 DOI: 10.1093/hmg/ddu580] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mutations in SQSTM1, encoding for the protein SQSTM1/p62, have been recently reported in 1-3.5% of patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration (ALS/FTLD). Inclusions positive for SQSTM1/p62 have been detected in patients with neurodegenerative disorders, including ALS/FTLD. In order to investigate the pathogenic mechanisms induced by SQSTM1 mutations in ALS/FTLD, we developed a zebrafish model. Knock-down of the sqstm1 zebrafish ortholog, as well as impairment of its splicing, led to a specific phenotype, consisting of behavioral and axonal anomalies. Here, we report swimming deficits associated with shorter motor neuronal axons that could be rescued by the overexpression of wild-type human SQSTM1. Interestingly, no rescue of the loss-of-function phenotype was observed when overexpressing human SQSTM1 constructs carrying ALS/FTLD-related mutations. Consistent with its role in autophagy regulation, we found increased mTOR levels upon knock-down of sqstm1. Furthermore, treatment of zebrafish embryos with rapamycin, a known inhibitor of the mTOR pathway, yielded an amelioration of the locomotor phenotype in the sqstm1 knock-down model. Our results suggest that loss-of-function of SQSTM1 causes phenotypic features characterized by locomotor deficits and motor neuron axonal defects that are associated with a misregulation of autophagic processes.
Collapse
Affiliation(s)
- Serena Lattante
- Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM; Inserm, U 1127, ICM; Cnrs, UMR 7225, ICM; ICM, Paris, F-75013 Paris, France
| | - Hortense de Calbiac
- Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM; Inserm, U 1127, ICM; Cnrs, UMR 7225, ICM; ICM, Paris, F-75013 Paris, France
| | - Isabelle Le Ber
- Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM; Inserm, U 1127, ICM; Cnrs, UMR 7225, ICM; ICM, Paris, F-75013 Paris, France, AP-HP, Hôpital de la Salpêtrière, Centre de Référence Démences Rares, F-75013, Paris, France
| | - Alexis Brice
- Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM; Inserm, U 1127, ICM; Cnrs, UMR 7225, ICM; ICM, Paris, F-75013 Paris, France, AP-HP, Hôpital de la Salpêtrière, Département de Génétique et Cytogénétique, F-75013, Paris, France
| | - Sorana Ciura
- Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM; Inserm, U 1127, ICM; Cnrs, UMR 7225, ICM; ICM, Paris, F-75013 Paris, France,
| | - Edor Kabashi
- Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM; Inserm, U 1127, ICM; Cnrs, UMR 7225, ICM; ICM, Paris, F-75013 Paris, France,
| |
Collapse
|
28
|
Casci I, Pandey UB. A fruitful endeavor: modeling ALS in the fruit fly. Brain Res 2014; 1607:47-74. [PMID: 25289585 DOI: 10.1016/j.brainres.2014.09.064] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 09/26/2014] [Accepted: 09/27/2014] [Indexed: 12/11/2022]
Abstract
For over a century Drosophila melanogaster, commonly known as the fruit fly, has been instrumental in genetics research and disease modeling. In more recent years, it has been a powerful tool for modeling and studying neurodegenerative diseases, including the devastating and fatal amyotrophic lateral sclerosis (ALS). The success of this model organism in ALS research comes from the availability of tools to manipulate gene/protein expression in a number of desired cell-types, and the subsequent recapitulation of cellular and molecular phenotypic features of the disease. Several Drosophila models have now been developed for studying the roles of ALS-associated genes in disease pathogenesis that allowed us to understand the molecular pathways that lead to motor neuron degeneration in ALS patients. Our primary goal in this review is to highlight the lessons we have learned using Drosophila models pertaining to ALS research. This article is part of a Special Issue entitled ALS complex pathogenesis.
Collapse
Affiliation(s)
- Ian Casci
- Department of Pediatrics, Child Neurology and Neurobiology, Children׳s Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA; Human Genetics Graduate Program, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
| | - Udai Bhan Pandey
- Department of Pediatrics, Child Neurology and Neurobiology, Children׳s Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA.
| |
Collapse
|
29
|
Chattopadhyay D, Sengupta S. First evidence of pathogenicity of V234I mutation of hVAPB found in Amyotrophic Lateral Sclerosis. Biochem Biophys Res Commun 2014; 448:108-13. [PMID: 24792378 DOI: 10.1016/j.bbrc.2014.04.102] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/16/2014] [Indexed: 10/25/2022]
Abstract
Amyotrophic Lateral Sclerosis is a motor neurodegenerative disease which is characterized by progressive loss of motor neurons followed by paralysis and eventually death. In human, VAMP-associated protein B (VAPB) is the causative gene of the familial form of ALS8. Previous studies have shown that P56S and T46I point mutations of hVAPB are present in this form of ALS. Recently, another mutation, V234I of hVAPB was found in one familial case of ALS. This is the first study where we have shown that V234I-VAPB does not form aggregate like other two mutants of VAPB and localizes differently than the wild type VAPB. It induces Ubiquitin aggregation followed by cell death. We propose that V234I-VAPB exhibits the characteristics of ALS in spite of not having the typical aggregation property of different mutations in various neurodegenerative diseases.
Collapse
Affiliation(s)
| | - Soma Sengupta
- Department of Biochemistry, University of Calcutta, India.
| |
Collapse
|