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Bertin F, Jara-Wilde J, Auer B, Köhler-Solís A, González-Silva C, Thomas U, Sierralta J. Drosophila Atlastin regulates synaptic vesicle mobilization independent of bone morphogenetic protein signaling. Biol Res 2023; 56:49. [PMID: 37710314 PMCID: PMC10503011 DOI: 10.1186/s40659-023-00462-1] [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: 06/08/2023] [Accepted: 09/01/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND The endoplasmic reticulum (ER) contacts endosomes in all parts of a motor neuron, including the axon and presynaptic terminal, to move structural proteins, proteins that send signals, and lipids over long distances. Atlastin (Atl), a large GTPase, is required for membrane fusion and the structural dynamics of the ER tubules. Atl mutations are the second most common cause of Hereditary Spastic Paraplegia (HSP), which causes spasticity in both sexes' lower extremities. Through an unknown mechanism, Atl mutations stimulate the BMP (bone morphogenetic protein) pathway in vertebrates and Drosophila. Synaptic defects are caused by atl mutations, which affect the abundance and distribution of synaptic vesicles (SV) in the bouton. We hypothesize that BMP signaling, does not cause Atl-dependent SV abnormalities in Drosophila. RESULTS We show that atl knockdown in motor neurons (Atl-KD) increases synaptic and satellite boutons in the same way that constitutively activating the BMP-receptor Tkv (thick veins) (Tkv-CA) increases the bouton number. The SV proteins Cysteine string protein (CSP) and glutamate vesicular transporter are reduced in Atl-KD and Tkv-CA larvae. Reducing the activity of the BMP receptor Wishful thinking (wit) can rescue both phenotypes. Unlike Tkv-CA larvae, Atl-KD larvae display altered activity-dependent distributions of CSP staining. Furthermore, Atl-KD larvae display an increased FM 1-43 unload than Control and Tkv-CA larvae. As decreasing wit function does not reduce the phenotype, our hypothesis that BMP signaling is not involved is supported. We also found that Rab11/CSP colocalization increased in Atl-KD larvae, which supports the concept that late recycling endosomes regulate SV movements. CONCLUSIONS Our findings reveal that Atl modulates neurotransmitter release in motor neurons via SV distribution independently of BMP signaling, which could explain the observed SV accumulation and synaptic dysfunction. Our data suggest that Atl is involved in membrane traffic as well as formation and/or recycling of the late endosome.
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Affiliation(s)
- Francisca Bertin
- Biomedical Neuroscience Institute (BNI), Santiago, Chile
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Jorge Jara-Wilde
- SCIAN-Lab, Biomedical Neuroscience Institute (BNI), Santiago, Chile
- Department of Computational Sciences, Faculty of Physical and Mathematical Sciences, Universidad de Chile, Santiago, Chile
| | - Benedikt Auer
- Laboratory of Neuronal and Synaptic Signals, Department of Cellular Neuroscience, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Andrés Köhler-Solís
- Biomedical Neuroscience Institute (BNI), Santiago, Chile
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Carolina González-Silva
- Biomedical Neuroscience Institute (BNI), Santiago, Chile
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Ulrich Thomas
- Functional Genetics of the Synapse, Department of Cellular Neuroscience, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany
| | - Jimena Sierralta
- Biomedical Neuroscience Institute (BNI), Santiago, Chile.
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
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Chu S, Xie X, Payan C, Stochaj U. Valosin containing protein (VCP): initiator, modifier, and potential drug target for neurodegenerative diseases. Mol Neurodegener 2023; 18:52. [PMID: 37545006 PMCID: PMC10405438 DOI: 10.1186/s13024-023-00639-y] [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: 02/20/2023] [Accepted: 06/27/2023] [Indexed: 08/08/2023] Open
Abstract
The AAA+ ATPase valosin containing protein (VCP) is essential for cell and organ homeostasis, especially in cells of the nervous system. As part of a large network, VCP collaborates with many cofactors to ensure proteostasis under normal, stress, and disease conditions. A large number of mutations have revealed the importance of VCP for human health. In particular, VCP facilitates the dismantling of protein aggregates and the removal of dysfunctional organelles. These are critical events to prevent malfunction of the brain and other parts of the nervous system. In line with this idea, VCP mutants are linked to the onset and progression of neurodegeneration and other diseases. The intricate molecular mechanisms that connect VCP mutations to distinct brain pathologies continue to be uncovered. Emerging evidence supports the model that VCP controls cellular functions on multiple levels and in a cell type specific fashion. Accordingly, VCP mutants derail cellular homeostasis through several mechanisms that can instigate disease. Our review focuses on the association between VCP malfunction and neurodegeneration. We discuss the latest insights in the field, emphasize open questions, and speculate on the potential of VCP as a drug target for some of the most devastating forms of neurodegeneration.
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Affiliation(s)
- Siwei Chu
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada
| | - Xinyi Xie
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada
| | - Carla Payan
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada
| | - Ursula Stochaj
- Department of Physiology, McGill University, Montreal, HG3 1Y6, Canada.
- Quantitative Life Sciences Program, McGill University, Montreal, Canada.
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Candia N, Ibacache A, Medina-Yáñez I, Olivares GH, Ramírez M, Vega-Macaya F, Couve A, Sierralta J, Olguín P. Identification of atlastin genetic modifiers in a model of hereditary spastic paraplegia in Drosophila. Hum Genet 2023; 142:1303-1315. [PMID: 37368047 DOI: 10.1007/s00439-023-02577-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 05/30/2023] [Indexed: 06/28/2023]
Abstract
Hereditary spastic paraplegias (HSPs) are a group of neurodegenerative disorders characterized by progressive dysfunction of corticospinal motor neurons. Mutations in Atlastin1/Spg3, a small GTPase required for membrane fusion in the endoplasmic reticulum, are responsible for 10% of HSPs. Patients with the same Atlastin1/Spg3 mutation present high variability in age at onset and severity, suggesting a fundamental role of the environment and genetic background. Here, we used a Drosophila model of HSPs to identify genetic modifiers of decreased locomotion associated with atlastin knockdown in motor neurons. First, we screened for genomic regions that modify the climbing performance or viability of flies expressing atl RNAi in motor neurons. We tested 364 deficiencies spanning chromosomes two and three and found 35 enhancer and four suppressor regions of the climbing phenotype. We found that candidate genomic regions can also rescue atlastin effects at synapse morphology, suggesting a role in developing or maintaining the neuromuscular junction. Motor neuron-specific knockdown of 84 genes spanning candidate regions of the second chromosome identified 48 genes required for climbing behavior in motor neurons and 7 for viability, mapping to 11 modifier regions. We found that atl interacts genetically with Su(z)2, a component of the Polycomb repressive complex 1, suggesting that epigenetic regulation plays a role in the variability of HSP-like phenotypes caused by atl alleles. Our results identify new candidate genes and epigenetic regulation as a mechanism modifying neuronal atl pathogenic phenotypes, providing new targets for clinical studies.
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Affiliation(s)
- Noemi Candia
- Programa de Genética Humana, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Andrés Ibacache
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Ignacio Medina-Yáñez
- Programa de Genética Humana, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Gonzalo H Olivares
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
- Escuela de Kinesiología, Facultad de Medicina y Ciencias de la Salud, Center for Integrative Biology (CIB), Universidad Mayor, Santiago, Chile
| | - Mauricio Ramírez
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Franco Vega-Macaya
- Programa de Genética Humana, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Andrés Couve
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Jimena Sierralta
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile
| | - Patricio Olguín
- Programa de Genética Humana, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile.
- Departamento de Neurociencia, Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453, Santiago, Chile.
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Xue Y, Jia PF, Li HJ. SUN3/4/5 proteins regulate endoplasmic reticulum tubule formation and luminal spacing in Arabidopsis. J Genet Genomics 2022; 50:370-373. [PMID: 36402306 DOI: 10.1016/j.jgg.2022.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/13/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022]
Affiliation(s)
- Yong Xue
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Peng-Fei Jia
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hong-Ju Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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Fowler PC, Byrne DJ, Blackstone C, O’Sullivan NC. Loss of the Mitochondrial Fission GTPase Drp1 Contributes to Neurodegeneration in a Drosophila Model of Hereditary Spastic Paraplegia. Brain Sci 2020; 10:brainsci10090646. [PMID: 32957716 PMCID: PMC7564485 DOI: 10.3390/brainsci10090646] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 09/10/2020] [Accepted: 09/15/2020] [Indexed: 02/03/2023] Open
Abstract
Mitochondrial morphology, distribution and function are maintained by the opposing forces of mitochondrial fission and fusion, the perturbation of which gives rise to several neurodegenerative disorders. The large guanosine triphosphate (GTP)ase dynamin-related protein 1 (Drp1) is a critical regulator of mitochondrial fission by mediating membrane scission, often at points of mitochondrial constriction at endoplasmic reticulum (ER)-mitochondrial contacts. Hereditary spastic paraplegia (HSP) subtype SPG61 is a rare neurodegenerative disorder caused by mutations in the ER-shaping protein Arl6IP1. We have previously reported defects in both the ER and mitochondrial networks in a Drosophila model of SPG61. In this study, we report that knockdown of Arl6IP1 lowers Drp1 protein levels, resulting in reduced ER–mitochondrial contacts and impaired mitochondrial load at the distal ends of long motor neurons. Increasing mitochondrial fission, by overexpression of wild-type Drp1 but not a dominant negative Drp1, increases ER–mitochondrial contacts, restores mitochondrial load within axons and partially rescues locomotor deficits. Arl6IP1 knockdown Drosophila also demonstrate impaired autophagic flux and an accumulation of ubiquitinated proteins, which occur independent of Drp1-mediated mitochondrial fission defects. Together, these findings provide evidence that impaired mitochondrial fission contributes to neurodegeneration in this in vivo model of HSP.
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Affiliation(s)
- Philippa C. Fowler
- UCD School of Biomolecular and Biomedical Sciences, UCD Conway Institute, University College Dublin, Dublin 4, Ireland; (P.C.F.); (D.J.B.)
| | - Dwayne J. Byrne
- UCD School of Biomolecular and Biomedical Sciences, UCD Conway Institute, University College Dublin, Dublin 4, Ireland; (P.C.F.); (D.J.B.)
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Craig Blackstone
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Niamh C. O’Sullivan
- UCD School of Biomolecular and Biomedical Sciences, UCD Conway Institute, University College Dublin, Dublin 4, Ireland; (P.C.F.); (D.J.B.)
- Correspondence: ; Tel.: +353-1-7166762
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Shih YT, Hsueh YP. The involvement of endoplasmic reticulum formation and protein synthesis efficiency in VCP- and ATL1-related neurological disorders. J Biomed Sci 2018; 25:2. [PMID: 29310658 PMCID: PMC5757295 DOI: 10.1186/s12929-017-0403-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/26/2017] [Indexed: 12/13/2022] Open
Abstract
The endoplasmic reticulum (ER) is the biggest organelle in cells and is involved in versatile cellular processes. Formation and maintenance of ER morphology are regulated by a series of proteins controlling membrane fusion and curvature. At least six different ER morphology regulators have been demonstrated to be involved in neurological disorders-including Valosin-containing protein (VCP), Atlastin-1 (ATL1), Spastin (SPAST), Reticulon 2 (RTN2), Receptor expression enhancing protein 1 (REEP1) and RAB10-suggesting a critical role of ER formation in neuronal activity and function. Among these genes, mutations in VCP gene involve in inclusion body myopathy with Paget disease of bone and frontotemporal dementia (IBMPFD), familial amyotrophic lateral sclerosis (ALS), autism spectrum disorders (ASD), and hereditary spastic paraplegia (HSP). ATL1 is also one of causative genes of HSP. RAB10 is associated with Parkinson's disease (PD). A recent study showed that VCP and ATL1 work together to regulate dendritic spine formation by controlling ER formation and consequent protein synthesis efficiency. RAB10 shares the same function with VCP and ATL1 to control ER formation and protein synthesis efficiency but acts independently. Increased protein synthesis by adding extra leucine to cultured neurons ameliorated dendritic spine deficits caused by VCP and ATL1 deficiencies, strengthening the significance of protein synthesis in VCP- and ATL1-regulated dendritic spine formation. These findings provide new insight into the roles of ER and protein synthesis in controlling dendritic spine formation and suggest a potential etiology of neurodegenerative disorders caused by mutations in VCP, ATL1 and other genes encoding proteins regulating ER formation and morphogenesis.
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Affiliation(s)
- Yu-Tzu Shih
- Institute of Molecular Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Taipei, 11529, Taiwan
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, 128, Academia Rd., Sec. 2, Taipei, 11529, Taiwan.
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Byrne DJ, Harmon MJ, Simpson JC, Blackstone C, O'Sullivan NC. Roles for the VCP co-factors Npl4 and Ufd1 in neuronal function in Drosophila melanogaster. J Genet Genomics 2017; 44:493-501. [PMID: 29037990 PMCID: PMC5666124 DOI: 10.1016/j.jgg.2017.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/02/2017] [Accepted: 06/19/2017] [Indexed: 12/18/2022]
Abstract
The VCP-Ufd1-Npl4 complex regulates proteasomal processing within cells by delivering ubiquitinated proteins to the proteasome for degradation. Mutations in VCP are associated with two neurodegenerative diseases, amyotrophic lateral sclerosis (ALS) and inclusion body myopathy with Paget's disease of the bone and frontotemporal dementia (IBMPFD), and extensive study has revealed crucial functions of VCP within neurons. By contrast, little is known about the functions of Npl4 or Ufd1 in vivo. Using neuronal-specific knockdown of Npl4 or Ufd1 in Drosophila melanogaster, we infer that Npl4 contributes to microtubule organization within developing motor neurons. Moreover, Npl4 RNAi flies present with neurodegenerative phenotypes including progressive locomotor deficits, reduced lifespan and increased accumulation of TAR DNA-binding protein-43 homolog (TBPH). Knockdown, but not overexpression, of TBPH also exacerbates Npl4 RNAi-associated adult-onset neurodegenerative phenotypes. In contrast, we find that neuronal knockdown of Ufd1 has little effect on neuromuscular junction (NMJ) organization, TBPH accumulation or adult behaviour. These findings suggest the differing neuronal functions of Npl4 and Ufd1 in vivo.
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Affiliation(s)
- Dwayne J Byrne
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Mark J Harmon
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jeremy C Simpson
- UCD School of Biology and Environmental Science, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
| | - Craig Blackstone
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Niamh C O'Sullivan
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
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VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation. Nat Commun 2016; 7:11020. [PMID: 26984393 PMCID: PMC4800434 DOI: 10.1038/ncomms11020] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 02/12/2016] [Indexed: 12/29/2022] Open
Abstract
Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders. Protein homeostasis is crucial for maintaining a variety of cellular functions. Here the authors show that valosin-containing protein and its cofactors regulate tubular ER formation and protein synthesis efficiency, thereby control dendritic spine formation in neurons.
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