1
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Peters B, Dattner T, Schlieben LD, Sun T, Staufner C, Lenz D. Disorders of vesicular trafficking presenting with recurrent acute liver failure: NBAS, RINT1, and SCYL1 deficiency. J Inherit Metab Dis 2024. [PMID: 38279772 DOI: 10.1002/jimd.12707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/11/2023] [Accepted: 12/13/2023] [Indexed: 01/28/2024]
Abstract
Among genetic disorders of vesicular trafficking, there are three causing recurrent acute liver failure (RALF): NBAS, RINT1, and SCYL1-associated disease. These three disorders are characterized by liver crises triggered by febrile infections and account for a relevant proportion of RALF causes. While the frequency and severity of liver crises in NBAS and RINT1-associated disease decrease with age, patients with SCYL1 variants present with a progressive, cholestatic course. In all three diseases, there is a multisystemic, partially overlapping phenotype with variable expression, including liver, skeletal, and nervous systems, all organ systems with high secretory activity. There are no specific biomarkers for these diseases, and whole exome sequencing should be performed in patients with RALF of unknown etiology. NBAS, SCYL1, and RINT1 are involved in antegrade and retrograde vesicular trafficking. Pathomechanisms remain unclarified, but there is evidence of a decrease in concentration and stability of the protein primarily affected by the respective gene defect and its interaction partners, potentially causing impairment of vesicular transport. The impairment of protein secretion by compromised antegrade transport provides a possible explanation for different organ manifestations such as bone alteration due to lack of collagens or diabetes mellitus when insulin secretion is affected. Dysfunction of retrograde transport impairs membrane recycling and autophagy. The impairment of vesicular trafficking results in increased endoplasmic reticulum stress, which, in hepatocytes, can progress to hepatocytolysis. While there is no curative therapy, an early and consequent implementation of an emergency protocol seems crucial for optimal therapeutic management.
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Affiliation(s)
- Bianca Peters
- Medical Faculty Heidelberg, Center for Paediatric and Adolescent Medicine, Department I, Division of Paediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Tal Dattner
- Medical Faculty Heidelberg, Center for Paediatric and Adolescent Medicine, Department I, Division of Paediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Lea D Schlieben
- School of Medicine, Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Computational Health Centre, Helmholtz Zentrum München, Neuherberg, Germany
| | - Tian Sun
- Medical Faculty Heidelberg, Center for Paediatric and Adolescent Medicine, Department I, Division of Paediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Christian Staufner
- Medical Faculty Heidelberg, Center for Paediatric and Adolescent Medicine, Department I, Division of Paediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Dominic Lenz
- Medical Faculty Heidelberg, Center for Paediatric and Adolescent Medicine, Department I, Division of Paediatric Neurology and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
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2
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Chen M, Xu L, Wu Y, Soba P, Hu C. The organization and function of the Golgi apparatus in dendrite development and neurological disorders. Genes Dis 2023; 10:2425-2442. [PMID: 37554209 PMCID: PMC10404969 DOI: 10.1016/j.gendis.2022.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/13/2022] [Accepted: 11/05/2022] [Indexed: 12/24/2022] Open
Abstract
Dendrites are specialized neuronal compartments that sense, integrate and transfer information in the neural network. Their development is tightly controlled and abnormal dendrite morphogenesis is strongly linked to neurological disorders. While dendritic morphology ranges from relatively simple to extremely complex for a specified neuron, either requires a functional secretory pathway to continually replenish proteins and lipids to meet dendritic growth demands. The Golgi apparatus occupies the center of the secretory pathway and is regulating posttranslational modifications, sorting, transport, and signal transduction, as well as acting as a non-centrosomal microtubule organization center. The neuronal Golgi apparatus shares common features with Golgi in other eukaryotic cell types but also forms distinct structures known as Golgi outposts that specifically localize in dendrites. However, the organization and function of Golgi in dendrite development and its impact on neurological disorders is just emerging and so far lacks a systematic summary. We describe the organization of the Golgi apparatus in neurons, review the current understanding of Golgi function in dendritic morphogenesis, and discuss the current challenges and future directions.
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Affiliation(s)
- Meilan Chen
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
- Department of Ophthalmology, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510320, China
| | - Lu Xu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
| | - Yi Wu
- Department of Ophthalmology, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510320, China
| | - Peter Soba
- LIMES Institute, Department of Molecular Brain Physiology and Behavior, University of Bonn, Bonn 53115, Germany
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91054, Germany
| | - Chun Hu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
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3
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Vitali T, Sanchez-Alvarez R, Witkos TM, Bantounas I, Cutiongco MFA, Dudek M, Yan G, Mironov AA, Swift J, Lowe M. Vimentin intermediate filaments provide structural stability to the mammalian Golgi complex. J Cell Sci 2023; 136:jcs260577. [PMID: 37732478 PMCID: PMC10617613 DOI: 10.1242/jcs.260577] [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: 08/25/2022] [Accepted: 09/18/2023] [Indexed: 09/22/2023] Open
Abstract
The Golgi complex comprises a connected ribbon of stacked cisternal membranes localized to the perinuclear region in most vertebrate cells. The position and morphology of this organelle depends upon interactions with microtubules and the actin cytoskeleton. In contrast, we know relatively little about the relationship of the Golgi complex with intermediate filaments (IFs). In this study, we show that the Golgi is in close physical proximity to vimentin IFs in cultured mouse and human cells. We also show that the trans-Golgi network coiled-coil protein GORAB can physically associate with vimentin IFs. Loss of vimentin and/or GORAB had a modest effect upon Golgi structure at the steady state. The Golgi underwent more rapid disassembly upon chemical disruption with brefeldin A or nocodazole, and slower reassembly upon drug washout, in vimentin knockout cells. Moreover, loss of vimentin caused reduced Golgi ribbon integrity when cells were cultured on high-stiffness hydrogels, which was exacerbated by loss of GORAB. These results indicate that vimentin IFs contribute to the structural stability of the Golgi complex and suggest a role for GORAB in this process.
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Affiliation(s)
- Teresa Vitali
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Rosa Sanchez-Alvarez
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Tomasz M. Witkos
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Ioannis Bantounas
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Marie F. A. Cutiongco
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
| | - Michal Dudek
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
| | - Guanhua Yan
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Alexander A. Mironov
- Electron Microscopy Core Facility, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Joe Swift
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
| | - Martin Lowe
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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4
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Mann JP, Lenz D, Stamataki Z, Kelly D. Common mechanisms in pediatric acute liver failure. Trends Mol Med 2023; 29:228-240. [PMID: 36496278 DOI: 10.1016/j.molmed.2022.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/06/2022] [Accepted: 11/14/2022] [Indexed: 12/12/2022]
Abstract
Acute liver failure (ALF) is a rare but potentially fatal disease in children. The etiology is multifactorial, including infection, autoimmune, and genetic disorders, as well as indeterminate hepatitis, which has a higher requirement for liver transplantation. Activation of the innate and adaptive immune systems leads to hepatocyte-specific injury which is mitigated by T regulatory cell activation. Recovery of the native liver depends on activation of apoptotic and regenerative pathways, including the integrated stress response (ISR; e.g., PERK), p53, and HNF4α. Loss-of-function mutations in these pathways cause recurrent ALF in response to non-hepatotropic viruses. Deeper understanding of these mechanisms will lead to improved diagnosis, management, and outcomes for pediatric ALF.
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Affiliation(s)
- Jake P Mann
- Liver Unit, Birmingham Women's and Children's Hospital, and University of Birmingham, Birmingham, UK
| | - Dominic Lenz
- Division of Neuropediatrics and Pediatric Metabolic Medicine, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Zania Stamataki
- Centre for Liver and Gastrointestinal Research, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
| | - Deirdre Kelly
- Liver Unit, Birmingham Women's and Children's Hospital, and University of Birmingham, Birmingham, UK; Centre for Liver and Gastrointestinal Research, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK.
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5
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Coexistence of spinocerebellar ataxia autosomal recessive type 21 and Ehlers-Danlos syndrome spondylodysplastic type 3 in a patient. Clin Dysmorphol 2023; 32:25-28. [PMID: 36503921 DOI: 10.1097/mcd.0000000000000435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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6
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Sun A, Tian X, Yang W, Lin Q. Overexpression of SCYL1 Is Associated with Progression of Breast Cancer. Curr Oncol 2022; 29:6922-6932. [PMID: 36290821 PMCID: PMC9600755 DOI: 10.3390/curroncol29100544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/15/2022] [Accepted: 09/21/2022] [Indexed: 01/13/2023] Open
Abstract
SCYL1 is a pseudokinase and plays roles in cell division and gene transcription, nuclear/cytoplasmic shuttling of tRNA, protein glycosylation, and Golgi morphology. However, the role of SCYL1 in human breast cancer progression remains largely unknown. In this study, we determined expression of SCYL1 in breast cancer by searching the Cancer Genome Atlas (TCGA) and Tumor Immunoassay Resource (TIMER) databases. Meanwhile, we collected breast tumor tissue samples from 247 cases and detected expression of SCYL1 in the tumors using the tissue microarray assay (TMA). Association of SCYL1 with prognosis of breast cancer was determined based on the PrognoScan database. The results have shown that SCYL1 is overexpressed in breast cancer, and the expression of SCYL1 is associated with poor clinical outcomes of breast cancer patients. Furthermore, knockdown of SCYL1 by shRNAs significantly inhibited the proliferation and migration of breast cancer cells. Taken together, our data suggest that SCYL1 is a biomarker for poor prognosis of breast cancer, has a promoting role in breast cancer progression, and is a potential target for breast cancer therapy.
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7
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mTORC1 controls Golgi architecture and vesicle secretion by phosphorylation of SCYL1. Nat Commun 2022; 13:4685. [PMID: 35948564 PMCID: PMC9365812 DOI: 10.1038/s41467-022-32487-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 07/30/2022] [Indexed: 12/04/2022] Open
Abstract
The protein kinase mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth and proliferation, supporting anabolic reactions and inhibiting catabolic pathways like autophagy. Its hyperactivation is a frequent event in cancer promoting tumor cell proliferation. Several intracellular membrane-associated mTORC1 pools have been identified, linking its function to distinct subcellular localizations. Here, we characterize the N-terminal kinase-like protein SCYL1 as a Golgi-localized target through which mTORC1 controls organelle distribution and extracellular vesicle secretion in breast cancer cells. Under growth conditions, SCYL1 is phosphorylated by mTORC1 on Ser754, supporting Golgi localization. Upon mTORC1 inhibition, Ser754 dephosphorylation leads to SCYL1 displacement to endosomes. Peripheral, dephosphorylated SCYL1 causes Golgi enlargement, redistribution of early and late endosomes and increased extracellular vesicle release. Thus, the mTORC1-controlled phosphorylation status of SCYL1 is an important determinant regulating subcellular distribution and function of endolysosomal compartments. It may also explain the pathophysiology underlying human genetic diseases such as CALFAN syndrome, which is caused by loss-of-function of SCYL1. mTORC1 is a master regulator of cell growth with well-known functions in inhibiting autophagic vesicle formation. Here, the authors show that mTORC1 also affects Golgi architecture and vesicle secretion by phosphorylating the scaffold protein SCYL1.
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8
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Pennauer M, Buczak K, Prescianotto-Baschong C, Spiess M. Shared and specific functions of Arfs 1-5 at the Golgi revealed by systematic knockouts. J Cell Biol 2022; 221:212750. [PMID: 34749397 PMCID: PMC8579194 DOI: 10.1083/jcb.202106100] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 09/14/2021] [Accepted: 10/04/2021] [Indexed: 12/22/2022] Open
Abstract
ADP-ribosylation factors (Arfs) are small GTPases regulating membrane traffic in the secretory pathway. They are closely related and appear to have overlapping functions, regulators, and effectors. The functional specificity of individual Arfs and the extent of redundancy are still largely unknown. We addressed these questions by CRISPR/Cas9-mediated genomic deletion of the human class I (Arf1/3) and class II (Arf4/5) Arfs, either individually or in combination. Most knockout cell lines were viable with slight growth defects only when lacking Arf1 or Arf4. However, Arf1+4 and Arf4+5 could not be deleted simultaneously. Class I Arfs are nonessential, and Arf4 alone is sufficient for viability. Upon Arf1 deletion, the Golgi was enlarged, and recruitment of vesicle coats decreased, confirming a major role of Arf1 in vesicle formation at the Golgi. Knockout of Arf4 caused secretion of ER-resident proteins, indicating specific defects in coatomer-dependent ER protein retrieval by KDEL receptors. The knockout cell lines will be useful tools to study other Arf-dependent processes.
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9
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Saito M, Nakayama M, Fujita K, Uchida A, Yano H, Goto S, Okazawa H, Sone M. Role of the Drosophila YATA protein in the proper subcellular localization of COPI revealed by in vivo analysis. Genes Genet Syst 2021; 95:303-314. [PMID: 33583916 DOI: 10.1266/ggs.20-00027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
yata mutants of Drosophila melanogaster exhibit phenotypes including progressive brain shrinkage, developmental abnormalities and shortened lifespan, whereas in mammals, null mutations of the yata ortholog Scyl1 result in motor neuron degeneration. yata mutation also causes defects in the anterograde intracellular trafficking of a subset of proteins including APPL, which is the Drosophila ortholog of mammalian APP, a causative molecule in Alzheimer's disease. SCYL1 binds and regulates the function of coat protein complex I (COPI) in secretory vesicles. Here, we reveal a role for the Drosophila YATA protein in the proper localization of COPI. Immunohistochemical analyses performed using confocal microscopy and structured illumination microscopy showed that YATA colocalizes with COPI and GM130, a cis-Golgi marker. Analyses using transgenically expressed YATA with a modified N-terminal sequence revealed that the N-terminal portion of YATA is required for the proper subcellular localization of YATA. Analysis using transgenically expressed YATA proteins in which the C-terminal sequence was modified revealed a function for the C-terminal portion of YATA in the subcellular localization of COPI. Notably, when YATA was mislocalized, it also caused the mislocalization of COPI, indicating that YATA plays a role in directing COPI to the proper subcellular site. Moreover, when both YATA and COPI were mislocalized, the staining pattern of GM130 revealed Golgi with abnormal elongated shapes. Thus, our in vivo data indicate that YATA plays a role in the proper subcellular localization of COPI.
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Affiliation(s)
- Maiko Saito
- Department of Biomolecular Science, Faculty of Science, Toho University
| | - Minoru Nakayama
- Department of Biomolecular Science, Faculty of Science, Toho University
| | - Kyota Fujita
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University
| | - Atsuko Uchida
- Department of Neuroscience, The Ohio State University
| | | | - Satoshi Goto
- Department of Life Science, College of Science, Rikkyo University
| | - Hitoshi Okazawa
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University
| | - Masaki Sone
- Department of Biomolecular Science, Faculty of Science, Toho University
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10
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Enkler L, Rinaldi B, de Craene JO, Hammann P, Nureki O, Senger B, Friant S, Becker HD. Cex1 is a component of the COPI intracellular trafficking machinery. Biol Open 2021; 10:bio.058528. [PMID: 33753324 PMCID: PMC8015235 DOI: 10.1242/bio.058528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
COPI (coatomer complex I) coated vesicles are involved in Golgi-to-ER and intra-Golgi trafficking pathways, and mediate retrieval of ER resident proteins. Functions and components of the COPI-mediated trafficking pathways, beyond the canonical set of Sec/Arf proteins, are constantly increasing in number and complexity. In mammalian cells, GORAB, SCYL1 and SCYL3 proteins regulate Golgi morphology and protein glycosylation in concert with the COPI machinery. Here, we show that Cex1, homologous to the mammalian SCYL proteins, is a component of the yeast COPI machinery, by interacting with Sec27, Sec28 and Sec33 (Ret1/Cop1) proteins of the COPI coat. Cex1 was initially reported to mediate channeling of aminoacylated tRNA outside of the nucleus. Our data show that Cex1 localizes at membrane compartments, on structures positive for the Sec33 α-COP subunit. Moreover, the Wbp1 protein required for N-glycosylation and interacting via its di-lysine motif with the Sec27 β′-COP subunit is mis-targeted in cex1Δ deletion mutant cells. Our data point to the possibility of developing Cex1 yeast-based models to study neurodegenerative disorders linked to pathogenic mutations of its human homologue SCYL1. Summary: Cex1, the yeast homologue of mammalian SCYL1, interacts with COPI coat components and is recruited to the Golgi to regulate retrograde vesicular trafficking and sorting
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Affiliation(s)
- Ludovic Enkler
- Génétique Moléculaire et Cellulaire, Université de Strasbourg, CNRS, GMGM UMR7156, F-67000 Strasbourg, France
| | - Bruno Rinaldi
- Génétique Moléculaire et Cellulaire, Université de Strasbourg, CNRS, GMGM UMR7156, F-67000 Strasbourg, France
| | - Johan Owen de Craene
- Génétique Moléculaire et Cellulaire, Université de Strasbourg, CNRS, GMGM UMR7156, F-67000 Strasbourg, France
| | - Philippe Hammann
- 'Architecture et Réactivité de l'ARN', Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, F-67000 Strasbourg, France
| | - Osamu Nureki
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan
| | - Bruno Senger
- Génétique Moléculaire et Cellulaire, Université de Strasbourg, CNRS, GMGM UMR7156, F-67000 Strasbourg, France
| | - Sylvie Friant
- Génétique Moléculaire et Cellulaire, Université de Strasbourg, CNRS, GMGM UMR7156, F-67000 Strasbourg, France
| | - Hubert D Becker
- Génétique Moléculaire et Cellulaire, Université de Strasbourg, CNRS, GMGM UMR7156, F-67000 Strasbourg, France
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11
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Fatalska A, Stepinac E, Richter M, Kovacs L, Pietras Z, Puchinger M, Dong G, Dadlez M, Glover DM. The dimeric Golgi protein Gorab binds to Sas6 as a monomer to mediate centriole duplication. eLife 2021; 10:e57241. [PMID: 33704067 PMCID: PMC8009671 DOI: 10.7554/elife.57241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/11/2021] [Indexed: 12/30/2022] Open
Abstract
The duplication and ninefold symmetry of the Drosophila centriole requires that the cartwheel molecule, Sas6, physically associates with Gorab, a trans-Golgi component. How Gorab achieves these disparate associations is unclear. Here, we use hydrogen-deuterium exchange mass spectrometry to define Gorab's interacting surfaces that mediate its subcellular localization. We identify a core stabilization sequence within Gorab's C-terminal coiled-coil domain that enables homodimerization, binding to Rab6, and thereby trans-Golgi localization. By contrast, part of the Gorab monomer's coiled-coil domain undergoes an antiparallel interaction with a segment of the parallel coiled-coil dimer of Sas6. This stable heterotrimeric complex can be visualized by electron microscopy. Mutation of a single leucine residue in Sas6's Gorab-binding domain generates a Sas6 variant with a sixteenfold reduced binding affinity for Gorab that cannot support centriole duplication. Thus, Gorab dimers at the Golgi exist in equilibrium with Sas6-associated monomers at the centriole to balance Gorab's dual role.
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Affiliation(s)
- Agnieszka Fatalska
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
| | - Emma Stepinac
- Department of Medical Biochemistry, Max Perutz Labs, Medical University of ViennaViennaAustria
| | - Magdalena Richter
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
| | - Levente Kovacs
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Zbigniew Pietras
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
| | - Martin Puchinger
- Department of Structural and Computational Biology, Max Perutz Labs, University of ViennaViennaAustria
| | - Gang Dong
- Department of Medical Biochemistry, Max Perutz Labs, Medical University of ViennaViennaAustria
| | - Michal Dadlez
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
| | - David M Glover
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
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12
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Fatalska A, Dzhindzhev NS, Dadlez M, Glover DM. Interaction interface in the C-terminal parts of centriole proteins Sas6 and Ana2. Open Biol 2020; 10:200221. [PMID: 33171067 PMCID: PMC7729032 DOI: 10.1098/rsob.200221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/20/2020] [Indexed: 12/14/2022] Open
Abstract
The centriole is a ninefold symmetrical structure found at the core of centrosomes and, as a basal body, at the base of cilia, whose conserved duplication is regulated by Plk4 kinase. Plk4 phosphorylates a single serine residue at the N-terminus of Ana2 to promote Ana2's loading to the site of procentriole formation. Four conserved serines in Ana2's STAN motif are then phosphorylated by Plk4, enabling Sas6 recruitment. Crystallographic data indicate that the coiled-coil domain of Ana2 forms a tetramer but the structure of full-length Ana2 has not been solved. Here, we have employed hydrogen-deuterium exchange coupled with mass spectrometry (HDX-MS) to uncover the conformational dynamics of Ana2, revealing the high flexibility of this protein with one rigid region. To determine the elusive nature of the interaction surfaces between Ana2 and Sas6, we have confirmed complex formation between the phosphomimetic form of Ana2 (Ana2-4D) and Sas6 in vitro and in vivo. Analysis of this complex by HDX-MS identifies short critical regions required for this interaction, which lie in the C-terminal parts of both proteins. Mutational studies confirmed the relevance of these regions for the Ana2-Sas6 interaction. The Sas6 site required for Ana2 binding is distinct from the site required for Sas6 to bind Gorab and Sas6 is able to bind both these protein partners simultaneously.
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Affiliation(s)
- Agnieszka Fatalska
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | | | - Michal Dadlez
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - David M. Glover
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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13
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Amano G, Matsuzaki S, Mori Y, Miyoshi K, Han S, Shikada S, Takamura H, Yoshimura T, Katayama T. SCYL1 arginine methylation by PRMT1 is essential for neurite outgrowth via Golgi morphogenesis. Mol Biol Cell 2020; 31:1963-1973. [PMID: 32583741 PMCID: PMC7543066 DOI: 10.1091/mbc.e20-02-0100] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Arginine methylation is a common posttranslational modification that modulates protein function. SCY1-like pseudokinase 1 (SCYL1) is crucial for neuronal functions and interacts with γ2-COP to form coat protein complex I (COPI) vesicles that regulate Golgi morphology. However, the molecular mechanism by which SCYL1 is regulated remains unclear. Here, we report that the γ2-COP-binding site of SCYL1 is arginine-methylated by protein arginine methyltransferase 1 (PRMT1) and that SCYL1 arginine methylation is important for the interaction of SCYL1 with γ2-COP. PRMT1 was colocalized with SCYL1 in the Golgi fraction. Inhibition of PRMT1 suppressed axon outgrowth and dendrite complexity via abnormal Golgi morphology. Knockdown of SCYL1 by small interfering RNA (siRNA) inhibited axon outgrowth, and the inhibitory effect was rescued by siRNA-resistant SCYL1, but not SCYL1 mutant, in which the arginine methylation site was replaced. Thus, PRMT1 regulates Golgi morphogenesis via SCYL1 arginine methylation. We propose that SCYL1 arginine methylation by PRMT1 contributes to axon and dendrite morphogenesis in neurons.
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Affiliation(s)
- Genki Amano
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shinsuke Matsuzaki
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Pharmacology, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-0012, Japan
| | - Yasutake Mori
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Anatomy, International University of Health and Welfare, 4-3 Kozunomori, Narita, Chiba, 286-8686, Japan
| | - Ko Miyoshi
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Sarina Han
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Sho Shikada
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hironori Takamura
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takeshi Yoshimura
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Taiichi Katayama
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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14
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Niu LG, Liu P, Wang ZW, Chen B. Slo2 potassium channel function depends on RNA editing-regulated expression of a SCYL1 protein. eLife 2020; 9:53986. [PMID: 32314960 PMCID: PMC7195191 DOI: 10.7554/elife.53986] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/20/2020] [Indexed: 12/28/2022] Open
Abstract
Slo2 potassium channels play important roles in neuronal function, and their mutations in humans may cause epilepsies and cognitive defects. However, it is largely unknown how Slo2 is regulated by other proteins. Here we show that the function of C. elegans Slo2 (SLO-2) depends on adr-1, a gene important to RNA editing. ADR-1 promotes SLO-2 function not by editing the transcripts of slo-2 but those of scyl-1, which encodes an orthologue of mammalian SCYL1. Transcripts of scyl-1 are greatly decreased in adr-1 mutants due to deficient RNA editing at a single adenosine in their 3’-UTR. SCYL-1 physically interacts with SLO-2 in neurons. Single-channel open probability (Po) of neuronal SLO-2 is ~50% lower in scyl-1 knockout mutant than wild type. Moreover, human Slo2.2/Slack Po is doubled by SCYL1 in a heterologous expression system. These results suggest that SCYL-1/SCYL1 is an evolutionarily conserved regulator of Slo2 channels.
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Affiliation(s)
- Long-Gang Niu
- Department of Neuroscience, University of Connecticut Health Center, Farmington, United States
| | - Ping Liu
- Department of Neuroscience, University of Connecticut Health Center, Farmington, United States
| | - Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut Health Center, Farmington, United States
| | - Bojun Chen
- Department of Neuroscience, University of Connecticut Health Center, Farmington, United States
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15
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Sánchez-Simarro J, Bernat-Silvestre C, Gimeno-Ferrer F, Selvi-Martínez P, Montero-Pau J, Aniento F, Marcote MJ. Loss of Arabidopsis β-COP Function Affects Golgi Structure, Plant Growth and Tolerance to Salt Stress. FRONTIERS IN PLANT SCIENCE 2020; 11:430. [PMID: 32351533 PMCID: PMC7175232 DOI: 10.3389/fpls.2020.00430] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 03/24/2020] [Indexed: 05/20/2023]
Abstract
The early secretory pathway involves bidirectional transport between the endoplasmic reticulum (ER) and the Golgi apparatus and is mediated by coat protein complex I (COPI)-coated and coat protein complex II (COPII)-coated vesicles. COPII vesicles are involved in ER to Golgi transport meanwhile COPI vesicles mediate intra-Golgi transport and retrograde transport from the Golgi apparatus to the ER. The key component of COPI vesicles is the coatomer complex, that is composed of seven subunits (α/β/β'/γ/δ/ε/ζ). In Arabidopsis two genes coding for the β-COP subunit have been identified, which are the result of recent tandem duplication. Here we have used a loss-of-function approach to study the function of β-COP. The results we have obtained suggest that β-COP is required for plant growth and salt tolerance. In addition, β-COP function seems to be required for maintaining the structure of the Golgi apparatus.
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16
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US3 Kinase-Mediated Phosphorylation of Tegument Protein VP8 Plays a Critical Role in the Cellular Localization of VP8 and Its Effect on the Lipid Metabolism of Bovine Herpesvirus 1-Infected Cells. J Virol 2019; 93:JVI.02151-18. [PMID: 30626671 DOI: 10.1128/jvi.02151-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 12/11/2018] [Indexed: 02/04/2023] Open
Abstract
Bovine herpesvirus 1 (BoHV-1) infects bovine species, causing respiratory infections, genital disorders and abortions. VP8 is the most abundant tegument protein of BoHV-1 and is critical for virus replication in cattle. In this study, the cellular transport of VP8 in BoHV-1-infected cells and its ability to alter the cellular lipid metabolism were investigated. A viral kinase, US3, was found to be involved in regulating these processes. In the early stages of infection VP8 was localized in the nucleus. Subsequently, presumably after completion of its role in the nucleus, VP8 was translocated to the cytoplasm. When US3 was deleted or the essential US3 phosphorylation site of VP8 was mutated in BoHV-1, the majority of VP8 was localized in the nuclei of infected cells. This suggests that phosphorylation by US3 may be critical for cytoplasmic localization of VP8. Eventually, the cytoplasmic VP8 was accumulated in the cis-Golgi apparatus but not in the trans-Golgi network, implying that VP8 was not involved in virion transport toward and budding from the cell membrane. VP8 caused lipid droplet (LD) formation in the nuclei of transfected cells and increased cellular cholesterol levels. Lipid droplets were not found in the nuclei of BoHV-1-infected cells when VP8 was cytoplasmic in the presence of US3. However, when US3 was deleted or phosphorylation residues in VP8 were mutated, nuclear VP8 and LDs appeared in BoHV-1-infected cells. The total cholesterol level was increased in BoHV-1-infected cells but not in ΔUL47-BoHV-1-infected cells, further supporting a role for VP8 in altering the cellular lipid metabolism during infection.IMPORTANCE Nuclear localization signals (NLSs) and nuclear export signals (NESs) are important elements directing VP8 to the desired locations in the BoHV-1-infected cell. In this study, a critical regulator that switches the nuclear and cytoplasmic localization of VP8 in BoHV-1-infected cells was identified. BoHV-1 used viral kinase US3 to regulate the cellular localization of VP8. Early during BoHV-1 infection VP8 was localized in the nucleus, where it performs various functions; once US3 was expressed, phosphorylated VP8 was cytoplasmic and ultimately accumulated in the cis-Golgi apparatus, presumably to be incorporated into virions. The Golgi localization of VP8 was only observed in virus-infected cells and not in US3-cotransfected cells, suggesting that this is mediated by other viral factors. Interestingly, VP8 was shown to cause increased cholesterol levels, which is a novel function for VP8 and a potential strategy to supply lipid for viral replication.
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17
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Li JQ, Gong JY, Knisely AS, Zhang MH, Wang JS. Recurrent acute liver failure associated with novel SCYL1 mutation: A case report. World J Clin Cases 2019; 7:494-499. [PMID: 30842961 PMCID: PMC6397814 DOI: 10.12998/wjcc.v7.i4.494] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/16/2019] [Accepted: 01/30/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Pediatric recurrent acute liver failure (RALF) with recovery between episodes is rare. Causes include autoimmune disease, which may flare and subside; intermittent exposure to toxins, as with ingestions; and metabolic disorders, among them the fever-associated crises ascribed to biallelic mutations in SCYL1, with RALF beginning in infancy. SCYL1 disease manifest with RALF, as known to date, includes central and peripheral neurologic and muscular morbidity (hepatocerebellar neuropathy syndrome). Primary ventilatory and skeletal diseases also have been noted in some reports.
CASE SUMMARY We describe a Han Chinese boy in whom fever-associated RALF began at age 14 mo. Bilateral femoral head abnormalities and mild impairment of neurologic function were first noted aged 8 years 6 mo. Liver biopsy after the third RALF episode (7 years) and during resolution of the fourth RALF episode (8 years 6 mo) found abnormal architecture and hepatic fibrosis, respectively. Whole-exome sequencing revealed homozygosity for the novel frameshift mutation c.92_93insGGGCCCT, p.(H32Gfs*20) in SCYL1 (parental heterozygosity confirmed).
CONCLUSION Our findings expand the mutational and clinical spectrum of SCYL1 disease. In our patient a substantial neurologic component was lacking and skeletal disease was identified relatively late.
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Affiliation(s)
- Jia-Qi Li
- Department of Pediatrics, Jinshan Hospital of Fudan University, Shanghai 201508, China
| | - Jing-Yu Gong
- Department of Pediatrics, Jinshan Hospital of Fudan University, Shanghai 201508, China
| | - A S Knisely
- Institut für Pathologie, Medizinische Universität Graz, Neue Stiftingtalstraße 6, Graz 8010, Austria
| | - Mei-Hong Zhang
- Department of Pediatrics, Jinshan Hospital of Fudan University, Shanghai 201508, China
| | - Jian-She Wang
- The Center for Pediatric Liver Diseases, Children’s Hospital of Fudan University, Shanghai 201102, China
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18
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Witkos TM, Chan WL, Joensuu M, Rhiel M, Pallister E, Thomas-Oates J, Mould AP, Mironov AA, Biot C, Guerardel Y, Morelle W, Ungar D, Wieland FT, Jokitalo E, Tassabehji M, Kornak U, Lowe M. GORAB scaffolds COPI at the trans-Golgi for efficient enzyme recycling and correct protein glycosylation. Nat Commun 2019; 10:127. [PMID: 30631079 PMCID: PMC6328613 DOI: 10.1038/s41467-018-08044-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 12/06/2018] [Indexed: 01/08/2023] Open
Abstract
COPI is a key mediator of protein trafficking within the secretory pathway. COPI is recruited to the membrane primarily through binding to Arf GTPases, upon which it undergoes assembly to form coated transport intermediates responsible for trafficking numerous proteins, including Golgi-resident enzymes. Here, we identify GORAB, the protein mutated in the skin and bone disorder gerodermia osteodysplastica, as a component of the COPI machinery. GORAB forms stable domains at the trans-Golgi that, via interactions with the COPI-binding protein Scyl1, promote COPI recruitment to these domains. Pathogenic GORAB mutations perturb Scyl1 binding or GORAB assembly into domains, indicating the importance of these interactions. Loss of GORAB causes impairment of COPI-mediated retrieval of trans-Golgi enzymes, resulting in a deficit in glycosylation of secretory cargo proteins. Our results therefore identify GORAB as a COPI scaffolding factor, and support the view that defective protein glycosylation is a major disease mechanism in gerodermia osteodysplastica.
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Affiliation(s)
- Tomasz M Witkos
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Wing Lee Chan
- Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Institut fuer Medizinische Genetik und Humangenetik, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, 13353, Germany
- FG Development & Disease, Max Planck Institut fuer Molekulare Genetik, Berlin, 14195, Germany
| | - Merja Joensuu
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
- Clem Jones Centre of Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Brisbane, QLD 4072, Australia
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland
| | - Manuel Rhiel
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, 69120, Germany
| | - Ed Pallister
- Department of Chemistry, University of York, York, YO10 5DG, UK
| | | | - A Paul Mould
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Alex A Mironov
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Christophe Biot
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Yann Guerardel
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Willy Morelle
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Daniel Ungar
- Department of Biology, University of York, York, YO10 5DD, UK
| | - Felix T Wieland
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, 69120, Germany
| | - Eija Jokitalo
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - May Tassabehji
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre (MAHSC), Manchester, M13 9WL, UK
| | - Uwe Kornak
- Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Institut fuer Medizinische Genetik und Humangenetik, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, 13353, Germany
- FG Development & Disease, Max Planck Institut fuer Molekulare Genetik, Berlin, 14195, Germany
| | - Martin Lowe
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.
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19
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Ferreira CR, Xia ZJ, Clément A, Parry DA, Davids M, Taylan F, Sharma P, Turgeon CT, Blanco-Sánchez B, Ng BG, Logan CV, Wolfe LA, Solomon BD, Cho MT, Douglas G, Carvalho DR, Bratke H, Haug MG, Phillips JB, Wegner J, Tiemeyer M, Aoki K, Nordgren A, Hammarsjö A, Duker AL, Rohena L, Hove HB, Ek J, Adams D, Tifft CJ, Onyekweli T, Weixel T, Macnamara E, Radtke K, Powis Z, Earl D, Gabriel M, Russi AHS, Brick L, Kozenko M, Tham E, Raymond KM, Phillips JA, Tiller GE, Wilson WG, Hamid R, Malicdan MC, Nishimura G, Grigelioniene G, Jackson A, Westerfield M, Bober MB, Gahl WA, Freeze HH, Gahl WA, Freeze HH. A Recurrent De Novo Heterozygous COG4 Substitution Leads to Saul-Wilson Syndrome, Disrupted Vesicular Trafficking, and Altered Proteoglycan Glycosylation. Am J Hum Genet 2018; 103:553-567. [PMID: 30290151 DOI: 10.1016/j.ajhg.2018.09.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 08/31/2018] [Indexed: 12/18/2022] Open
Abstract
The conserved oligomeric Golgi (COG) complex is involved in intracellular vesicular transport, and is composed of eight subunits distributed in two lobes, lobe A (COG1-4) and lobe B (COG5-8). We describe fourteen individuals with Saul-Wilson syndrome, a rare form of primordial dwarfism with characteristic facial and radiographic features. All affected subjects harbored heterozygous de novo variants in COG4, giving rise to the same recurrent amino acid substitution (p.Gly516Arg). Affected individuals' fibroblasts, whose COG4 mRNA and protein were not decreased, exhibited delayed anterograde vesicular trafficking from the ER to the Golgi and accelerated retrograde vesicular recycling from the Golgi to the ER. This altered steady-state equilibrium led to a decrease in Golgi volume, as well as morphologic abnormalities with collapse of the Golgi stacks. Despite these abnormalities of the Golgi apparatus, protein glycosylation in sera and fibroblasts from affected subjects was not notably altered, but decorin, a proteoglycan secreted into the extracellular matrix, showed altered Golgi-dependent glycosylation. In summary, we define a specific heterozygous COG4 substitution as the molecular basis of Saul-Wilson syndrome, a rare skeletal dysplasia distinct from biallelic COG4-CDG.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - William A Gahl
- Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hudson H Freeze
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
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20
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Variant in SCYL1 gene causes aberrant splicing in a family with cerebellar ataxia, recurrent episodes of liver failure, and growth retardation. Eur J Hum Genet 2018; 27:263-268. [PMID: 30258122 DOI: 10.1038/s41431-018-0268-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 08/01/2018] [Accepted: 08/28/2018] [Indexed: 12/12/2022] Open
Abstract
Herein, we describe two members of one family who presented with recurrent episodes of hepatic failure, cerebellar ataxia, peripheral neuropathy, and short stature. Liver transplantation was considered. Whole-exome sequencing (Trio) revealed a synonymous variant in exon 4 of SCYL1:c.459C>T p. (Gly153Gly), which did not appear to affect the protein sequence. Computational prediction analysis suggested that this modification could alter the SCYL1 mRNA splicing processing to create a premature termination codon. The SCYL1 mRNAs in our patient's lymphocytes were analyzed and aberrant splicing was found. Molecular analysis of family members identified the parents as heterozygous recessive carriers and the proband as well as an affected aunt as homozygous. Evidently, harmless synonymous variants in the SCYL1 gene can damage gene splicing and hence the expression. We confirmed that the pathogenicity of this variant in the SCYL1 gene was associated with spinocerebellar ataxia, autosomal recessive 21 (SCAR21). Other reported cases (accept one) of liver failure found in the SCYL1 variants resolved during childhood, therefore orthotropic liver transplantation was no longer appropriate.
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21
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Kovacs L, Chao-Chu J, Schneider S, Gottardo M, Tzolovsky G, Dzhindzhev NS, Riparbelli MG, Callaini G, Glover DM. Gorab is a Golgi protein required for structure and duplication of Drosophila centrioles. Nat Genet 2018; 50:1021-1031. [PMID: 29892014 PMCID: PMC6097609 DOI: 10.1038/s41588-018-0149-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 04/17/2018] [Indexed: 11/09/2022]
Abstract
We demonstrate that a Drosophila Golgi protein, Gorab, is present not only in the trans-Golgi but also in the centriole cartwheel where, complexed to Sas6, it is required for centriole duplication. In addition to centriole defects, flies lacking Gorab are uncoordinated due to defects in sensory cilia, which lose their nine-fold symmetry. We demonstrate the separation of centriole and Golgi functions of Drosophila Gorab in two ways: first, we have created Gorab variants that are unable to localize to trans-Golgi but can still rescue the centriole and cilia defects of gorab null flies; second, we show that expression of C-terminally tagged Gorab disrupts Golgi functions in cytokinesis of male meiosis, a dominant phenotype overcome by mutations preventing Golgi targeting. Our findings suggest that during animal evolution, a Golgi protein has arisen with a second, apparently independent, role in centriole duplication.
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Affiliation(s)
| | - Jennifer Chao-Chu
- University of Cambridge, Cambridge, UK
- The University of Hong Kong, Hong Kong, China
| | | | - Marco Gottardo
- University of Siena, Siena, Italy
- Alexander von Humboldt Foundation Fellow, Center for Molecular Medicine and Institute for Biochemistry of the University of Cologne, Cologne, Germany
| | - George Tzolovsky
- University of Cambridge, Cambridge, UK
- Carl Zeiss Microscopy Ltd, ZEISS Group, Cambridge, UK
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22
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Abstract
The coat protein complex I (COPI) allows the precise sorting of lipids and proteins between Golgi cisternae and retrieval from the Golgi to the ER. This essential role maintains the identity of the early secretory pathway and impinges on key cellular processes, such as protein quality control. In this Cell Science at a Glance and accompanying poster, we illustrate the different stages of COPI-coated vesicle formation and revisit decades of research in the context of recent advances in the elucidation of COPI coat structure. By calling attention to an array of questions that have remained unresolved, this review attempts to refocus the perspectives of the field.
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Affiliation(s)
- Eric C Arakel
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany .,Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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23
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SCYL1 variants cause a syndrome with low γ-glutamyl-transferase cholestasis, acute liver failure, and neurodegeneration (CALFAN). Genet Med 2018; 20:1255-1265. [PMID: 29419818 PMCID: PMC5989927 DOI: 10.1038/gim.2017.260] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/27/2017] [Indexed: 02/07/2023] Open
Abstract
Purpose Biallelic mutations in SCYL1 were
recently identified as causing a syndromal disorder characterized by peripheral
neuropathy, cerebellar atrophy, ataxia, and recurrent episodes of liver failure.
The occurrence of SCYL1 deficiency among patients with previously undetermined
infantile cholestasis or acute liver failure has not been studied; furthermore,
little is known regarding the hepatic phenotype. Methods We aimed to identify patients with SCYL1 variants within an exome-sequencing study of individuals
with infantile cholestasis or acute liver failure of unknown etiology. Deep
clinical and biochemical phenotyping plus analysis of liver biopsies and
functional studies on fibroblasts were performed. Results Seven patients from five families with biallelic SCYL1 variants were identified. The main clinical
phenotype was recurrent low γ-glutamyl-transferase (GGT) cholestasis or acute
liver failure with onset in infancy and a variable neurological phenotype of
later onset (CALFAN syndrome). Liver crises were triggered by febrile infections
and were transient, but fibrosis developed. Functional studies emphasize that
SCYL1 deficiency is linked to impaired intracellular trafficking. Conclusion SCYL1 deficiency can cause recurrent low-GGT cholestatic liver
dysfunction in conjunction with a variable neurological phenotype. Like NBAS
deficiency, it is a member of the emerging group of congenital disorders of
intracellular trafficking causing hepatopathy.
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Overlapping Role of SCYL1 and SCYL3 in Maintaining Motor Neuron Viability. J Neurosci 2018; 38:2615-2630. [PMID: 29437892 DOI: 10.1523/jneurosci.2282-17.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/23/2017] [Accepted: 01/31/2018] [Indexed: 11/21/2022] Open
Abstract
Members of the SCY1-like (SCYL) family of protein kinases are evolutionarily conserved and ubiquitously expressed proteins characterized by an N-terminal pseudokinase domain, centrally located Huntingtin, elongation factor 3, protein phosphatase 2A, yeast kinase TOR1 repeats, and an overall disorganized C-terminal segment. In mammals, three family members encoded by genes Scyl1, Scyl2, and Scyl3 have been described. Studies have pointed to a role for SCYL1 and SCYL2 in regulating neuronal function and viability in mice and humans, but little is known about the biological function of SCYL3. Here, we show that the biochemical and cell biological properties of SCYL3 are similar to those of SCYL1 and both proteins work in conjunction to maintain motor neuron viability. Specifically, although lack of Scyl3 in mice has no apparent effect on embryogenesis and postnatal life, it accelerates the onset of the motor neuron disorder caused by Scyl1 deficiency. Growth abnormalities, motor dysfunction, hindlimb paralysis, muscle wasting, neurogenic atrophy, motor neuron degeneration, and loss of large-caliber axons in peripheral nerves occurred at an earlier age in Scyl1/Scyl3 double-deficient mice than in Scyl1-deficient mice. Disease onset also correlated with the mislocalization of TDP-43 in spinal motor neurons, suggesting that SCYL1 and SCYL3 regulate TDP-43 proteostasis. Together, our results demonstrate an overlapping role for SCYL1 and SCYL3 in vivo and highlight the importance the SCYL family of proteins in regulating neuronal function and survival. Only male mice were used in this study.SIGNIFICANCE STATEMENT SCYL1 and SCYL2, members of the SCY1-like family of pseudokinases, have well established roles in neuronal function. Herein, we uncover the role of SCYL3 in maintaining motor neuron viability. Although targeted disruption of Scyl3 in mice had little or no effect on embryonic development and postnatal life, it accelerated disease onset associated with the loss of Scyl1, a novel motor neuron disease gene in humans. Scyl1 and Scyl3 double-deficient mice had neuronal defects characteristic of amyotrophic lateral sclerosis, including TDP-43 pathology, at an earlier age than did Scyl1-deficient mice. Thus, we show that SCYL1 and SCYL3 play overlapping roles in maintaining motor neuronal viability in vivo and confirm that SCYL family members are critical regulators of neuronal function and survival.
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25
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Incecik F, Herguner OM, Willems P, Mungan NO. Spinocerebellar Ataxia-21 in a Turkish Child. Ann Indian Acad Neurol 2018; 21:68-70. [PMID: 29720801 PMCID: PMC5909149 DOI: 10.4103/aian.aian_415_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Hereditary cerebellar ataxias are genetically heterogeneous disorders. Autosomal recessive spinocerebellar ataxia-21 (SCAR21) is a neurologic disorder characterized by the onset of cerebellar ataxia, recurrent episodes of liver failure, peripheral neuropathy, and learning disabilities. Herein, we reported a case presented with gait and balance problems, swallowing difficulties, mild delayed motor development, and mild learning disability with SCAR21 that confirmed by mutation analysis in a Turkish child. To the best of our knowledge, this is the first case of SCAR21 from Turkey.
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Affiliation(s)
- Faruk Incecik
- Department of Pediatric Neurology, Medical Faculty, Cukurova University, Adana, Turkey,Address for correspondence: Dr. Faruk Incecik, Toros Mah., Baris Manço Bul. 78178 Sok., Yesilpark Evleri, Kat: 7, No: 13, Çukurova, Adana, Turkey. E-mail:
| | - Ozlem M. Herguner
- Department of Pediatric Neurology, Medical Faculty, Cukurova University, Adana, Turkey
| | | | - Neslihan O. Mungan
- Department of Pediatric Neurology, Medical Faculty, Cukurova University, Adana, Turkey
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Jung JY, Lee DW, Ryu SB, Hwang I, Schachtman DP. SCYL2 Genes Are Involved in Clathrin-Mediated Vesicle Trafficking and Essential for Plant Growth. PLANT PHYSIOLOGY 2017; 175:194-209. [PMID: 28751315 PMCID: PMC5580775 DOI: 10.1104/pp.17.00824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 07/24/2017] [Indexed: 05/10/2023]
Abstract
Protein transport between organelles is an essential process in all eukaryotic cells and is mediated by the regulation of processes such as vesicle formation, transport, docking, and fusion. In animals, SCY1-LIKE2 (SCYL2) binds to clathrin and has been shown to play roles in trans-Golgi network-mediated clathrin-coated vesicle trafficking. Here, we demonstrate that SCYL2A and SCYL2B, which are Arabidopsis (Arabidopsis thaliana) homologs of animal SCYL2, are vital for plant cell growth and root hair development. Studies of the SCYL2 isoforms using multiple single or double loss-of-function alleles show that SCYL2B is involved in root hair development and that SCYL2A and SCYL2B are essential for plant growth and development and act redundantly in those processes. Quantitative reverse transcription-polymerase chain reaction and a β-glucuronidase-aided promoter assay show that SCYL2A and SCYL2B are differentially expressed in various tissues. We also show that SCYL2 proteins localize to the Golgi, trans-Golgi network, and prevacuolar compartment and colocalize with Clathrin Heavy Chain1 (CHC1). Furthermore, bimolecular fluorescence complementation and coimmunoprecipitation data show that SCYL2B interacts with CHC1 and two Soluble NSF Attachment Protein Receptors (SNAREs): Vesicle Transport through t-SNARE Interaction11 (VTI11) and VTI12. Finally, we present evidence that the root hair tip localization of Cellulose Synthase-Like D3 is dependent on SCYL2B. These findings suggest the role of SCYL2 genes in plant cell developmental processes via clathrin-mediated vesicle membrane trafficking.
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Affiliation(s)
- Ji-Yul Jung
- Department of Plant Molecular Biology, University of Lausanne, Lausanne 1015, Switzerland
| | - Dong Wook Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Stephen Beungtae Ryu
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Korea
| | - Inhwan Hwang
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Daniel P Schachtman
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68588
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Kowalczyk KM, Petersen J. Fission Yeast SCYL1/2 Homologue Ppk32: A Novel Regulator of TOR Signalling That Governs Survival during Brefeldin A Induced Stress to Protein Trafficking. PLoS Genet 2016; 12:e1006041. [PMID: 27191590 PMCID: PMC4871519 DOI: 10.1371/journal.pgen.1006041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 04/19/2016] [Indexed: 12/02/2022] Open
Abstract
Target of Rapamycin (TOR) signalling allows eukaryotic cells to adjust cell growth in response to changes in their nutritional and environmental context. The two distinct TOR complexes (TORC1/2) localise to the cell’s internal membrane compartments; the endoplasmic reticulum (ER), Golgi apparatus and lysosomes/vacuoles. Here, we show that Ppk32, a SCYL family pseudo-kinase, is a novel regulator of TOR signalling. The absence of ppk32 expression confers resistance to TOR inhibition. Ppk32 inhibition of TORC1 is critical for cell survival following Brefeldin A (BFA) induced stress. Treatment of wild type cells with either the TORC1 specific inhibitor rapamycin or the general TOR inhibitor Torin1 confirmed that a reduction in TORC1 activity promoted recovery from BFA induced stress. Phosphorylation of Ppk32 on two residues that are conserved within the SCYL pseudo-kinase family are required for this TOR inhibition. Phosphorylation on these sites controls Ppk32 protein levels and sensitivity to BFA. BFA induced ER stress does not account for the response to BFA that we report here, however BFA is also known to induce Golgi stress and impair traffic to lysosomes. In summary, Ppk32 reduce TOR signalling in response to BFA induced stress to support cell survival. The Target of Rapamycin (TOR) pathway plays a central role coordinating cell growth and cell division in response to the different cellular environments. This is achieved by TOR controlling various metabolic processes, cell growth and cell division, and in part by the localisation of TOR protein complexes to specific internal endomembranes and compartments. Here, we report a novel role for the SCYL family pseudo-kinase, Ppk32 in restraining TOR signalling when cells experience stresses, which specifically affect endomembranes and compartments where TOR complexes are localised. Cells exposed to endomembrane stress (induced by Brefeldin A), displayed increased cell survival when simultaneously treated with the TOR complex 1 (TORC1) inhibitor, rapamycin, presumably because the reduction in TORC1 signalling slows cellular processes to allow cells sufficient time to recover and adapt to this stress. Importantly cancer, neuro-degeneration and neurological diseases are all associated with stress to the endomembrane protein trafficking system. Our findings suggest that therapeutic rapamycin treatment to reduce TOR signalling and block proliferation of cancer cells, which are inherently experiencing such stress, may have the unintended consequence of enhancing cell survival. It is notable, therefore, that our reported mechanisms to reduce Ppk32 protein levels, likely to be conserved in humans, may represent a way to increase TOR signalling and thus increase cell death of cancer types with inherent stress to these internal membrane systems.
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Affiliation(s)
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, Australia
- South Australia Health and Medical Research Institute, Adelaide, Australia
- * E-mail:
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Abstract
The generation of mice lacking SCYL1 or SCYL2 and the identification of Scyl1 as the causative gene in the motor neuron disease mouse model muscle deficient (Scyl1mdf/mdf) demonstrated the importance of the SCY1-like family of protein pseudokinases in neuronal function and survival. Several essential cellular processes such as intracellular trafficking and nuclear tRNA export are thought to be regulated by SCYL proteins. However, whether deregulation of these processes contributes to the neurodegenerative processes associated with the loss of SCYL proteins is still unclear. Here, I briefly review the evidence supporting that SCYL proteins play a role in these processes and discuss their possible involvement in the neuronal functions of SCYL proteins. I also propose ways to determine the importance of these pathways for the functions of SCYL proteins in vivo.
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Affiliation(s)
- Stephane Pelletier
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
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Ghanem E, Al-Balushi M. Adopting the rapamycin trapping assay to track the trafficking of murine MHC class I alleles, H-2K(b). BMC Cell Biol 2015; 16:30. [PMID: 26714929 PMCID: PMC4696223 DOI: 10.1186/s12860-015-0077-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 12/14/2015] [Indexed: 11/22/2022] Open
Abstract
Background In mammalian cells, the quality control (QC) of properly folded proteins is monitored in the early secretory pathway, particularly in the endoplasmic reticulum (ER). Several proteins, including our protein of interest, major histocompatibility complex class I (MHC class I), can bypass the first line of ER-QC and reside in post-ER compartments in an unfolded form. Such forms entail both monomeric and dimeric structures that are devoid of peptides and thus cannot fulfill the immunological function of antigen presentation at the cell surface. MHC class I structures become mature and properly folded once loaded with the appropriate peptides in the framework of the peptide loading complex (PLC). Despite the flood of information on the diverse trafficking behavior of different MHC class I alleles, there is still controversy on the actual trajectory followed by improperly folded murine MHC class I alleles, namely H-2Kb. In this study, we employ an in vitro rapamycin trapping assay, live cell imaging, and a biochemical COPII budding approach to further investigate the trafficking of H-2Kb beyond the level of the ER. Results We confirm the egress of H-2Kb in an unfolded form to a post-ER compartment from where they can cycle back to the ER. Deciphering the exact identity of the post-ER compartment by laser scanning microscopy did not only point to the existence of the ERGIC and cis-Golgi compartments as residency areas for unfolded proteins, but also to the involvement of an addional compartment, that lies in close proximity and possesses high resemblance to the aforementioned compartments. Interestingly, we were capable of showing using the same rapamycin trapping assay that H-2Kb can undergo a potential maturation event during their cycling; this is attained upon addition of peptides and trapping of accumulated post-ER molecules at the cell surface. Conclusions Our findings deepen the understanding of H-2Kb trafficking outside the ER and pave the way to decipher the role and the trafficking of certain PLC chaperones, such as tapasin, throughout H-2Kb post-ER QC. Finally, we demonstrate the plausible usage of the rapamycin assay to assess the trafficking of defected proteins especially in diseases and under therapeutic studies.
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Affiliation(s)
- Esther Ghanem
- Department of Biology, Faculty of Natural and Applied Sciences, Notre Dame University, 72, Zouk Mosbeh, Keserwan district, Lebanon.
| | - Mohammed Al-Balushi
- Department of Microbiology and Immunology, Sultan Qaboos University, Muscat, Oman.
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Haase G, Rabouille C. Golgi Fragmentation in ALS Motor Neurons. New Mechanisms Targeting Microtubules, Tethers, and Transport Vesicles. Front Neurosci 2015; 9:448. [PMID: 26696811 PMCID: PMC4672084 DOI: 10.3389/fnins.2015.00448] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/13/2015] [Indexed: 12/12/2022] Open
Abstract
Pathological alterations of the Golgi apparatus, such as its fragmentation represent an early pre-clinical feature of many neurodegenerative diseases and have been widely studied in the motor neuron disease amyotrophic lateral sclerosis (ALS). Yet, the underlying molecular mechanisms have remained cryptic. In principle, Golgi fragmentation may result from defects in three major classes of proteins: structural Golgi proteins, cytoskeletal proteins and molecular motors, as well as proteins mediating transport to and through the Golgi. Here, we present the different mechanisms that may underlie Golgi fragmentation in animal and cellular models of ALS linked to mutations in SOD1, TARDBP (TDP-43), VAPB, and C9Orf72 and we propose a novel one based on findings in progressive motor neuronopathy (pmn) mice. These mice are mutated in the TBCE gene encoding the cis-Golgi localized tubulin-binding cofactor E, one of five chaperones that assist in tubulin folding and microtubule polymerization. Loss of TBCE leads to alterations in Golgi microtubules, which in turn impedes on the maintenance of the Golgi architecture. This is due to down-regulation of COPI coat components, dispersion of Golgi tethers and strong accumulation of ER-Golgi SNAREs. These effects are partially rescued by the GTPase ARF1 through recruitment of TBCE to the Golgi. We hypothesize that defects in COPI vesicles, microtubules and their interaction may also underlie Golgi fragmentation in human ALS linked to other mutations, spinal muscular atrophy (SMA), and related motor neuron diseases. We also discuss the functional relevance of pathological Golgi alterations, in particular their potential causative, contributory, or compensatory role in the degeneration of motor neuron cell bodies, axons and synapses.
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Affiliation(s)
- Georg Haase
- Centre National de la Recherche Scientifique and Aix-Marseille Université UMR 7289, Institut de Neurosciences de la Timone Marseille, France
| | - Catherine Rabouille
- The Department of Cell Biology, Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht Utrecht, Netherlands
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Schmidt WM, Rutledge SL, Schüle R, Mayerhofer B, Züchner S, Boltshauser E, Bittner RE. Disruptive SCYL1 Mutations Underlie a Syndrome Characterized by Recurrent Episodes of Liver Failure, Peripheral Neuropathy, Cerebellar Atrophy, and Ataxia. Am J Hum Genet 2015; 97:855-61. [PMID: 26581903 DOI: 10.1016/j.ajhg.2015.10.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/16/2015] [Indexed: 12/15/2022] Open
Abstract
Hereditary ataxias comprise a group of genetically heterogeneous disorders characterized by clinically variable cerebellar dysfunction and accompanied by involvement of other organ systems. The molecular underpinnings for many of these diseases are widely unknown. Previously, we discovered the disruption of Scyl1 as the molecular basis of the mouse mutant mdf, which is affected by neurogenic muscular atrophy, progressive gait ataxia with tremor, cerebellar vermis atrophy, and optic-nerve thinning. Here, we report on three human individuals, from two unrelated families, who presented with recurrent episodes of acute liver failure in early infancy and are affected by cerebellar vermis atrophy, ataxia, and peripheral neuropathy. By whole-exome sequencing, compound-heterozygous mutations within SCYL1 were identified in all affected individuals. We further show that in SCYL1-deficient human fibroblasts, the Golgi apparatus is massively enlarged, which is in line with the concept that SCYL1 regulates Golgi integrity. Thus, our findings define SCYL1 mutations as the genetic cause of a human hepatocerebellar neuropathy syndrome.
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Affiliation(s)
- Wolfgang M Schmidt
- Neuromuscular Research Department, Center of Anatomy and Cell Biology, Medical University of Vienna, 1090 Vienna, Austria
| | - S Lane Rutledge
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Rebecca Schüle
- Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany; German Research Center for Neurodegenerative Diseases, University of Tübingen, 72076 Tübingen, Germany; Dr. John T. Macdonald Department of Human Genetics and John P. Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Benjamin Mayerhofer
- Neuromuscular Research Department, Center of Anatomy and Cell Biology, Medical University of Vienna, 1090 Vienna, Austria
| | - Stephan Züchner
- Dr. John T. Macdonald Department of Human Genetics and John P. Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Eugen Boltshauser
- Division of Pediatric Neurology, University Children's Hospital, 8032 Zurich, Switzerland
| | - Reginald E Bittner
- Neuromuscular Research Department, Center of Anatomy and Cell Biology, Medical University of Vienna, 1090 Vienna, Austria.
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Suckling RJ, Poon PP, Travis SM, Majoul IV, Hughson FM, Evans PR, Duden R, Owen DJ. Structural basis for the binding of tryptophan-based motifs by δ-COP. Proc Natl Acad Sci U S A 2015; 112:14242-7. [PMID: 26578768 PMCID: PMC4655537 DOI: 10.1073/pnas.1506186112] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Coatomer consists of two subcomplexes: the membrane-targeting, ADP ribosylation factor 1 (Arf1):GTP-binding βγδζ-COP F-subcomplex, which is related to the adaptor protein (AP) clathrin adaptors, and the cargo-binding αβ'ε-COP B-subcomplex. We present the structure of the C-terminal μ-homology domain of the yeast δ-COP subunit in complex with the WxW motif from its binding partner, the endoplasmic reticulum-localized Dsl1 tether. The motif binds at a site distinct from that used by the homologous AP μ subunits to bind YxxΦ cargo motifs with its two tryptophan residues sitting in compatible pockets. We also show that the Saccharomyces cerevisiae Arf GTPase-activating protein (GAP) homolog Gcs1p uses a related WxxF motif at its extreme C terminus to bind to δ-COP at the same site in the same way. Mutations designed on the basis of the structure in conjunction with isothermal titration calorimetry confirm the mode of binding and show that mammalian δ-COP binds related tryptophan-based motifs such as that from ArfGAP1 in a similar manner. We conclude that δ-COP subunits bind Wxn(1-6)[WF] motifs within unstructured regions of proteins that influence the lifecycle of COPI-coated vesicles; this conclusion is supported by the observation that, in the context of a sensitizing domain deletion in Dsl1p, mutating the tryptophan-based motif-binding site in yeast causes defects in both growth and carboxypeptidase Y trafficking/processing.
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Affiliation(s)
- Richard J Suckling
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Pak Phi Poon
- Department of Microbiology and Immunology, Dalhousie University, Halifax, N.S., Canada B3H 4R2
| | - Sophie M Travis
- Department of Molecular Biology, Princeton University, Princeton NJ 08544
| | - Irina V Majoul
- Institute of Biology, Center for Structural and Cell Biology in Medicine, University of Lübeck, 23562 Lübeck, Germany
| | | | - Philip R Evans
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Rainer Duden
- Institute of Biology, Center for Structural and Cell Biology in Medicine, University of Lübeck, 23562 Lübeck, Germany
| | - David J Owen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
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SCYL2 Protects CA3 Pyramidal Neurons from Excitotoxicity during Functional Maturation of the Mouse Hippocampus. J Neurosci 2015. [PMID: 26203146 DOI: 10.1523/jneurosci.2056-14.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Neuronal death caused by excessive excitatory signaling, excitotoxicity, plays a central role in neurodegenerative disorders. The mechanisms regulating this process, however, are still incompletely understood. Here we show that the coated vesicle-associated kinase SCYL2/CVAK104 plays a critical role for the normal functioning of the nervous system and for suppressing excitotoxicity in the developing hippocampus. Targeted disruption of Scyl2 in mice caused perinatal lethality in the vast majority of newborn mice and severe sensory-motor deficits in mice that survived to adulthood. Consistent with a neurogenic origin of these phenotypes, neuron-specific deletion of Scyl2 also caused perinatal lethality in the majority of newborn mice and severe neurological defects in adult mice. The neurological deficits in these mice were associated with the degeneration of several neuronal populations, most notably CA3 pyramidal neurons of the hippocampus, which we analyzed in more detail. The loss of CA3 neurons occurred during the functional maturation of the hippocampus and was the result of a BAX-dependent apoptotic process. Excessive excitatory signaling was present at the onset of degeneration, and inhibition of excitatory signaling prevented the degeneration of CA3 neurons. Biochemical fractionation reveals that Scyl2-deficient mice have an altered composition of excitatory receptors at synapses. Our findings demonstrate an essential role for SCYL2 in regulating neuronal function and survival and suggest a role for SCYL2 in regulating excitatory signaling in the developing brain. Significance statement: Here we examine the in vivo function of SCYL2, an evolutionarily conserved and ubiquitously expressed protein pseudokinase thought to regulate protein trafficking along the secretory pathway, and demonstrate its importance for the normal functioning of the nervous system and for suppressing excitatory signaling in the developing brain. Together with recent studies demonstrating a role of SCYL1 in preventing motor neuron degeneration, our findings clearly establish the SCY1-like family of protein pseudokinases as key regulators of neuronal function and survival.
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Egerer J, Emmerich D, Fischer-Zirnsak B, Chan WL, Meierhofer D, Tuysuz B, Marschner K, Sauer S, Barr FA, Mundlos S, Kornak U. GORAB Missense Mutations Disrupt RAB6 and ARF5 Binding and Golgi Targeting. J Invest Dermatol 2015; 135:2368-2376. [PMID: 26000619 DOI: 10.1038/jid.2015.192] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 04/21/2015] [Accepted: 04/23/2015] [Indexed: 11/09/2022]
Abstract
Gerodermia osteodysplastica is a hereditary segmental progeroid disorder affecting skin, connective tissues, and bone that is caused by loss-of-function mutations in GORAB. The golgin, RAB6-interacting (GORAB) protein localizes to the Golgi apparatus and interacts with the small GTPase RAB6. In this study, we used different approaches to shed more light on the recruitment of GORAB to this compartment. We show that GORAB best colocalizes with trans-Golgi markers and is rapidly displaced upon Brefeldin A exposition, indicating a loose association with Golgi membranes. A yeast two-hybrid screening revealed a specific interaction with the small GTPase ADP-ribosylation factor (ARF5) in its active, GTP-bound form. ARF5 and RAB6 bind to GORAB via the same internal Golgi-targeting RAB6 and ARF5 binding (IGRAB) domain. Two GORAB missense mutations identified in gerodermia osteodysplastica patients fall within this IGRAB domain. GORAB carrying the mutation p.Ala220Pro had a cytoplasmic distribution and failed to interact with both RAB6 and ARF5. In contrast, the p.Ser175Phe mutation displaced GORAB from the Golgi compartment to vesicular structures and selectively impaired ARF5 binding. Our findings indicate that the IGRAB domain is crucial for the Golgi localization of GORAB and that loss of this localization impairs its physiological function.
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Affiliation(s)
- Johannes Egerer
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany; Max-Planck-Institut fuer Molekulare Genetik, FG Development & Disease, Berlin, Germany
| | - Denise Emmerich
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany; Max-Planck-Institut fuer Molekulare Genetik, FG Development & Disease, Berlin, Germany
| | - Björn Fischer-Zirnsak
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany; Max-Planck-Institut fuer Molekulare Genetik, FG Development & Disease, Berlin, Germany
| | - Wing Lee Chan
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany; Max-Planck-Institut fuer Molekulare Genetik, FG Development & Disease, Berlin, Germany
| | - David Meierhofer
- Max-Planck-Institut fuer Molekulare Genetik, Mass Spectrometry Facility, Berlin, Germany
| | - Beyhan Tuysuz
- Department of Pediatric Genetics, Cerrahpaşa Medical Faculty, Istanbul University, Istanbul, Turkey
| | - Katrin Marschner
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany
| | - Sascha Sauer
- Max-Planck-Institut fuer Molekulare Genetik, Otto-Warburg-Laboratories, Berlin, Germany
| | - Francis A Barr
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Stefan Mundlos
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany; Max-Planck-Institut fuer Molekulare Genetik, FG Development & Disease, Berlin, Germany; Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité-Universitaetsmedizin Berlin, Berlin, Germany
| | - Uwe Kornak
- Institut fuer Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin Berlin, Berlin, Germany; Max-Planck-Institut fuer Molekulare Genetik, FG Development & Disease, Berlin, Germany; Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité-Universitaetsmedizin Berlin, Berlin, Germany.
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Farhan H. Systems biology of the secretory pathway: what have we learned so far? Biol Cell 2015; 107:205-17. [PMID: 25756903 DOI: 10.1111/boc.201400065] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 03/04/2015] [Indexed: 12/26/2022]
Abstract
Several RNAi screens were performed in search for regulators of the secretory pathway. These screens were performed in different organisms and cell lines and relied on different readouts. Therefore, they have only little overlap among their hits, leading to the question of what we have learned from this approach so far and how these screens contributed towards an integrative understanding of the endomembrane system. The aim of this review is to revisit these screens and discuss their strengths and weaknesses as well as potential reasons for their failure to overlap with each other. As with secretory trafficking, RNAi screens were also performed on other cellular processes such as cell migration and autophagy, both of which were shown to be intimately linked to secretion. Another aim of this review is to compare the outcome of the RNAi screens on secretion, autophagy and cell migration and ask whether the functional genomic approaches have uncovered potential mechanistic insights into the links between these processes.
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Affiliation(s)
- Hesso Farhan
- Department of Biology, University of Konstanz, Konstanz, Germany.,Biotechnology Institute Thurgau, Kreuzlingen, Switzerland
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36
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Liu S, Storrie B. How Rab proteins determine Golgi structure. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:1-22. [PMID: 25708460 DOI: 10.1016/bs.ircmb.2014.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rab proteins, small GTPases, are key regulators of mammalian Golgi apparatus organization. Based on the effect of Rab activation state, Rab proteins fall into two functional classes. In Class1, inactivation induces Golgi ribbon fragmentation and/or redistribution of Golgi enzymes to the Endoplasmic Reticulum, while overexpression of wild type or activation has little, if any, effect on Golgi ribbon organization. In Class 2, the reverse is true. We give emphasis to Rab6, the most abundant Golgi-associated Rab protein. Rab6 depletion in HeLa cells causes an increase in Golgi cisternal number, longer, more continuous cisternae, and a pronounced accumulation of vesicles; the effect of Rab6 on Golgi ribbon organization is probably through regulation of vesicle transport. In effector studies, motor proteins and their regulators are found to be key Rab6 effectors. A related Rab, Rab41, affects Golgi ribbon organization in a contrasting manner. The balance between minus- and plus-end directed motor recruitment may well be the major Rab-dependent factor in Golgi ribbon organization.
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Affiliation(s)
- Shijie Liu
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Brian Storrie
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Yu Z, Ge Y, Xie L, Zhang T, Huang L, Zhao X, Liu J, Huang G. Using a yeast two-hybrid system to identify FTCD as a new regulator for HIF-1α in HepG2 cells. Cell Signal 2014; 26:1560-6. [DOI: 10.1016/j.cellsig.2014.03.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 02/16/2014] [Accepted: 03/16/2014] [Indexed: 12/15/2022]
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Hamlin JNR, Schroeder LK, Fotouhi M, Dokainish H, Ioannou MS, Girard M, Summerfeldt N, Melançon P, McPherson PS. Scyl1 scaffolds class II Arfs to specific subcomplexes of coatomer through the γ-COP appendage domain. J Cell Sci 2014; 127:1454-63. [PMID: 24481816 DOI: 10.1242/jcs.136481] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Coatomer (COPI)-coated vesicles mediate membrane trafficking in the early secretory pathway. There are at least three subclasses of COPI coats and two classes of Arf GTPases that couple COPI coat proteins to membranes. Whether mechanisms exist to link specific Arfs to specific COPI subcomplexes is unknown. We now demonstrate that Scy1-like protein 1 (Scyl1), a member of the Scy1-like family of catalytically inactive protein kinases, oligomerizes through centrally located HEAT repeats and uses a C-terminal RKXX-COO(-) motif to interact directly with the appendage domain of coatomer subunit γ-2 (also known as COPG2 or γ2-COP). Through a distinct site, Scyl1 interacts selectively with class II Arfs, notably Arf4, thus linking class II Arfs to γ2-bearing COPI subcomplexes. Therefore, Scyl1 functions as a scaffold for key components of COPI coats, and disruption of the scaffolding function of Scyl1 causes tubulation of the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) and the cis-Golgi, similar to that observed following the loss of Arf and Arf-guanine-nucleotide-exchange factor (GEF) function. Our data reveal that Scyl1 is a key organizer of a subset of the COPI machinery.
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Affiliation(s)
- Jason N R Hamlin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
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De Matteis MA, Vicinanza M, Venditti R, Wilson C. Cellular Assays for Drug Discovery in Genetic Disorders of Intracellular Trafficking. Annu Rev Genomics Hum Genet 2013; 14:159-90. [DOI: 10.1146/annurev-genom-091212-153415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | | | - Cathal Wilson
- Telethon Institute of Genetics and Medicine, 80131 Naples, Italy;
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RNAi screening reveals a large signaling network controlling the Golgi apparatus in human cells. Mol Syst Biol 2013; 8:629. [PMID: 23212246 PMCID: PMC3542528 DOI: 10.1038/msb.2012.59] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 10/11/2012] [Indexed: 12/11/2022] Open
Abstract
RNAi screening and automated image analysis reveal 180 kinases and phosphatases regulating the organization of the Golgi apparatus. Most of these genes also control the expression of specific glycans, pointing to a web of interactions between signaling cascades and glycosylation at the Golgi. ![]()
Golgi organization was probed with three markers of different Golgi compartments and quantitative morphological analysis. Knockdowns of ∼20% of all known kinases and phosphatases affected the Golgi globally or in a compartment-specific manner, and were comparable in degree to the depletion of known membrane traffic regulators such as SNAREs. Several cell surface receptors, their cognate ligands and downstream effectors regulate Golgi organization, suggesting a large regulatory network. Most signaling genes affected both Golgi morphology and the expression of specific glycans.
The Golgi apparatus has many important physiological functions, including sorting of secretory cargo and biosynthesis of complex glycans. These functions depend on the intricate and compartmentalized organization of the Golgi apparatus. To investigate the mechanisms that regulate Golgi architecture, we developed a quantitative morphological assay using three different Golgi compartment markers and quantitative image analysis, and performed a kinome- and phosphatome-wide RNAi screen in HeLa cells. Depletion of 159 signaling genes, nearly 20% of genes assayed, induced strong and varied perturbations in Golgi morphology. Using bioinformatics data, a large regulatory network could be constructed. Specific subnetworks are involved in phosphoinositides regulation, acto-myosin dynamics and mitogen activated protein kinase signaling. Most gene depletion also affected Golgi functions, in particular glycan biosynthesis, suggesting that signaling cascades can control glycosylation directly at the Golgi level. Our results provide a genetic overview of the signaling pathways that control the Golgi apparatus in human cells.
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An early onset progressive motor neuron disorder in Scyl1-deficient mice is associated with mislocalization of TDP-43. J Neurosci 2013; 32:16560-73. [PMID: 23175812 DOI: 10.1523/jneurosci.1787-12.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The molecular and cellular bases of motor neuron diseases (MNDs) are still poorly understood. The diseases are mostly sporadic, with ~10% of cases being familial. In most cases of familial motor neuronopathy, the disease is caused by either gain-of-adverse-effect mutations or partial loss-of-function mutations in ubiquitously expressed genes that serve essential cellular functions. Here we show that deletion of Scyl1, an evolutionarily conserved and ubiquitously expressed gene encoding the COPI-associated protein pseudokinase SCYL1, causes an early onset progressive MND with characteristic features of amyotrophic lateral sclerosis (ALS). Skeletal muscles of Scyl1(-/-) mice displayed neurogenic atrophy, fiber type switching, and disuse atrophy. Peripheral nerves showed axonal degeneration. Loss of lower motor neurons (LMNs) and large-caliber axons was conspicuous in Scyl1(-/-) animals. Signs of neuroinflammation were seen throughout the CNS, most notably in the ventral horn of the spinal cord. Neural-specific, but not skeletal muscle-specific, deletion of Scyl1 was sufficient to cause motor dysfunction, indicating that SCYL1 acts in a neural cell-autonomous manner to prevent LMN degeneration and motor functions. Remarkably, deletion of Scyl1 resulted in the mislocalization and accumulation of TDP-43 (TAR DNA-binding protein of 43 kDa) and ubiquilin 2 into cytoplasmic inclusions within LMNs, features characteristic of most familial and sporadic forms of ALS. Together, our results identify SCYL1 as a key regulator of motor neuron survival, and Scyl1(-/-) mice share pathological features with many human neurodegenerative conditions.
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Esteban-Pretel G, Marín MP, Romero AM, Timoneda J, Ponsoda X, Ballestín R, Renau-Piqueras J. Polyphosphoinositide metabolism and Golgi complex morphology in hippocampal neurons in primary culture is altered by chronic ethanol exposure. Alcohol Alcohol 2012; 48:15-27. [PMID: 23118092 DOI: 10.1093/alcalc/ags117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AIMS Ethanol affects not only the cytoskeletal organization and activity, but also intracellular trafficking in neurons in the primary culture. Polyphosphoinositide (PPIn) are essential regulators of many important cell functions, including those mentioned, cytoskeleton integrity and intracellular vesicle trafficking. Since information about the effect of chronic ethanol exposure on PPIn metabolism in neurons is scarce, this study analysed the effect of this treatment on three of these phospholipids. METHODS Phosphatidylinositol (PtdIns) levels as well as the activity and/or levels of enzymes involved in their metabolism were analysed in neurons chronically exposed to ethanol. The levels of phospholipases C and D, and phosphatidylethanol formation were also assessed. The consequence of the possible alterations in the levels of PtdIns on the Golgi complex (GC) was also analysed. RESULTS We show that phosphatidylinositol (4,5)-bisphosphate and phosphatidylinositol (3,4,5)-trisphosphate levels, both involved in the control of intracellular trafficking and cytoskeleton organization, decrease in ethanol-exposed hippocampal neurons. In contrast, several kinases that participate in the metabolism of these phospholipids, and the level and/or activity of phospholipases C and D, increase in cells after ethanol exposure. Ethanol also promotes phosphatidylethanol formation in neurons, which can result in the suppression of phosphatidic acid synthesis and, therefore, in PPIn biosynthesis. This treatment also lowers the phosphatidylinositol 4-phosphate levels, the main PPIn in the GC, with alterations in their morphology and in the levels of some of the proteins involved in structure maintenance. CONCLUSIONS The deregulation of the metabolism of PtdIns may underlie the ethanol-induced alterations on different neuronal processes, including intracellular trafficking and cytoskeletal integrity.
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Affiliation(s)
- Guillermo Esteban-Pretel
- Corresponding author: Sección de Biología y Patología Celular, Centro de Investigación, Hospital Universitario La Fe, Avda. Campanar 21, Valencia, Spain.
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Kirkbride KC, Hong NH, French CL, Clark ES, Jerome WG, Weaver AM. Regulation of late endosomal/lysosomal maturation and trafficking by cortactin affects Golgi morphology. Cytoskeleton (Hoboken) 2012; 69:625-43. [PMID: 22991200 PMCID: PMC3746372 DOI: 10.1002/cm.21051] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/11/2012] [Accepted: 07/11/2012] [Indexed: 01/23/2023]
Abstract
Cortactin is a branched actin regulator and tumor-overexpressed protein that promotes vesicular trafficking at a variety of cellular sites, including endosomes and the trans-Golgi network. To better understand its role in secretory trafficking, we investigated its function in Golgi homeostasis. Here, we report that knockdown (KD) of cortactin leads to a dramatic change in Golgi morphology by light microscopy, dependent on binding the Arp2/3 actin-nucleating complex. Surprisingly, there was little effect of cortactin-KD on anterograde trafficking of the constitutive cargo vesicular stomatitis virus glycoprotein (VSVG), Golgi assembly from endoplasmic reticulum membranes upon Brefeldin A washout, or Golgi ultrastructure. Instead, electron microscopy studies revealed that cortactin-KD cells contained a large number of immature-appearing late endosomal/lysosomal (LE/Lys) hybrid organelles, similar to those found in lysosomal storage diseases. Consistent with a defect in LE/Lys trafficking, cortactin-KD cells also exhibited accumulation of free cholesterol and retention of the retrograde Golgi cargo mannose-6-phosphate receptor in LE. Inhibition of LE maturation by treatment of control cells with Rab7 siRNA or chloroquine led to a compact Golgi morphology similar to that observed in cortactin-KD cells. Furthermore, the Golgi morphology defects of cortactin-KD cells could be rescued by removal of cholesterol-containing lipids from the media, suggesting that buildup of cholesterol-rich membranes in immature LE/Lys induced disturbances in retrograde trafficking. Taken together, these data reveal that LE/Lys maturation and trafficking are highly sensitive to cortactin-regulated branched actin assembly and suggests that cytoskeletal-induced Golgi morphology changes can be a consequence of altered trafficking at late endosomes.
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Affiliation(s)
- Kellye C Kirkbride
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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Affiliation(s)
| | - Adam D. Linstedt
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15232;
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Abstract
A number of long coiled-coil proteins are present on the Golgi. Often referred to as "golgins," they are well conserved in evolution and at least five are likely to have been present in the last common ancestor of all eukaryotes. Individual golgins are found in different parts of the Golgi stack, and they are typically anchored to the membrane at their carboxyl termini by a transmembrane domain or by binding a small GTPase. They appear to have roles in membrane traffic and Golgi structure, but their precise function is in most cases unclear. Many have binding sites for Rab family GTPases along their length, and this has led to the suggestion that the golgins act collectively to form a tentacular matrix that surrounds the Golgi to capture Rab-coated membranes in the vicinity of the stack. Such a collective role might explain the lack of cell lethality seen following loss of some of the genes in human familial conditions or mouse models.
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Abstract
The eukaryotic Golgi apparatus is characterized by a stack of flattened cisternae that are surrounded by transport vesicles. The organization and function of the Golgi require Golgi matrix proteins, including GRASPs and golgins, which exist primarily as fiber-like bridges between Golgi cisternae or between cisternae and vesicles. In this review, we highlight recent findings on Golgi matrix proteins, including their roles in maintaining the Golgi structure, vesicle tethering, and novel, unexpected functions. These new discoveries further our understanding of the molecular mechanisms that maintain the structure and the function of the Golgi, as well as its relationship with other cellular organelles such as the centrosome.
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Palmisano R, Golfi P, Heimann P, Shaw C, Troakes C, Schmitt-John T, Bartsch JW. Endosomal accumulation of APP in wobbler motor neurons reflects impaired vesicle trafficking: implications for human motor neuron disease. BMC Neurosci 2011; 12:24. [PMID: 21385376 PMCID: PMC3058068 DOI: 10.1186/1471-2202-12-24] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 03/07/2011] [Indexed: 02/08/2023] Open
Abstract
Background The cause of sporadic amyotrophic lateral sclerosis (ALS) is largely unknown but hypotheses about disease mechanisms include oxidative stress, defective axonal transport, mitochondrial dysfunction and disrupted RNA processing. Whereas familial ALS is well represented by transgenic mutant SOD1 mouse models, the mouse mutant wobbler (WR) develops progressive motor neuron degeneration due to a point mutation in the Vps54 gene, and provides an animal model for sporadic ALS. VPS54 protein as a component of a protein complex is involved in vesicular Golgi trafficking; impaired vesicle trafficking might also be mechanistic in the pathogenesis of human ALS. Results In motor neurons of homozygous symptomatic WR mice, a massive number of endosomal vesicles significantly enlarged (up to 3 μm in diameter) were subjected to ultrastructural analysis and immunohistochemistry for the endosome-specific small GTPase protein Rab7 and for amyloid precursor protein (APP). Enlarged vesicles were neither detected in heterozygous WR nor in transgenic SOD1(G93A) mice; in WR motor neurons, numerous APP/Rab7-positive vesicles were observed which were mostly LC3-negative, suggesting they are not autophagosomes. Conclusions We conclude that endosomal APP/Rab7 staining reflects impaired vesicle trafficking in WR mouse motor neurons. Based on these findings human ALS tissues were analysed for APP in enlarged vesicles and were detected in spinal cord motor neurons in six out of fourteen sporadic ALS cases. These enlarged vesicles were not detected in any of the familial ALS cases. Thus our study provides the first evidence for wobbler-like aetiologies in human ALS and suggests that the genes encoding proteins involved in vesicle trafficking should be screened for pathogenic mutations.
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Affiliation(s)
- Ralf Palmisano
- Pharmaceutical Science Research Division, King's College London, 150 Stamford Street, London, UK
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Tillement L, Lecanu L, Papadopoulos V. Further Evidence on Mitochondrial Targeting of β-Amyloid and Specificity of β-Amyloid-Induced Mitotoxicity in Neurons. NEURODEGENER DIS 2011; 8:331-44. [DOI: 10.1159/000323264] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 11/29/2010] [Indexed: 01/13/2023] Open
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