1
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Buchan JR. Stress granule and P-body clearance: Seeking coherence in acts of disappearance. Semin Cell Dev Biol 2024; 159-160:10-26. [PMID: 38278052 PMCID: PMC10939798 DOI: 10.1016/j.semcdb.2024.01.002] [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: 01/04/2024] [Accepted: 01/07/2024] [Indexed: 01/28/2024]
Abstract
Stress granules and P-bodies are conserved cytoplasmic biomolecular condensates whose assembly and composition are well documented, but whose clearance mechanisms remain controversial or poorly described. Such understanding could provide new insight into how cells regulate biomolecular condensate formation and function, and identify therapeutic strategies in disease states where aberrant persistence of stress granules in particular is implicated. Here, I review and compare the contributions of chaperones, the cytoskeleton, post-translational modifications, RNA helicases, granulophagy and the proteasome to stress granule and P-body clearance. Additionally, I highlight the potentially vital role of RNA regulation, cellular energy, and changes in the interaction networks of stress granules and P-bodies as means of eliciting clearance. Finally, I discuss evidence for interplay of distinct clearance mechanisms, suggest future experimental directions, and suggest a simple working model of stress granule clearance.
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Affiliation(s)
- J Ross Buchan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson 85716, United States.
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2
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Li C, Warren DT, Zhou C, De Silva S, Wilson DGS, Garcia-Maya M, Wheeler MA, Meinke P, Sawyer G, Ehler E, Wehnert M, Rao L, Zhang Q, Shanahan CM. Nesprin-2 is a novel scaffold protein for telethonin and FHL-2 in the cardiomyocyte sarcomere. J Biol Chem 2024; 300:107254. [PMID: 38569934 PMCID: PMC11078644 DOI: 10.1016/j.jbc.2024.107254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 03/11/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024] Open
Abstract
Nesprins comprise a family of multi-isomeric scaffolding proteins, forming the linker of nucleoskeleton-and-cytoskeleton complex with lamin A/C, emerin and SUN1/2 at the nuclear envelope. Mutations in nesprin-1/-2 are associated with Emery-Dreifuss muscular dystrophy (EDMD) with conduction defects and dilated cardiomyopathy (DCM). We have previously observed sarcomeric staining of nesprin-1/-2 in cardiac and skeletal muscle, but nesprin function in this compartment remains unknown. In this study, we show that specific nesprin-2 isoforms are highly expressed in cardiac muscle and localize to the Z-disc and I band of the sarcomere. Expression of GFP-tagged nesprin-2 giant spectrin repeats 52 to 53, localized to the sarcomere of neonatal rat cardiomyocytes. Yeast two-hybrid screening of a cardiac muscle cDNA library identified telethonin and four-and-half LIM domain (FHL)-2 as potential nesprin-2 binding partners. GST pull-down and immunoprecipitation confirmed the individual interactions between nesprin-2/telethonin and nesprin-2/FHL-2, and showed that nesprin-2 and telethonin binding was dependent on telethonin phosphorylation status. Importantly, the interactions between these binding partners were impaired by mutations in nesprin-2, telethonin, and FHL-2 identified in EDMD with DCM and hypertrophic cardiomyopathy patients. These data suggest that nesprin-2 is a novel sarcomeric scaffold protein that may potentially participate in the maintenance and/or regulation of sarcomeric organization and function.
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Affiliation(s)
- Chen Li
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK; Department of Cardiology, West China Hospital of Sichuan University, Chengdu, China
| | - Derek T Warren
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK; School of Pharmacy, University of East Anglia, Norwich, UK
| | - Can Zhou
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK
| | - Shanelle De Silva
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK
| | - Darren G S Wilson
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK
| | - Mitla Garcia-Maya
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Matthew A Wheeler
- Department of Cardiac Development and Remodeling, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Peter Meinke
- Friedrich-Baur-Institute at the Department of Neurology, LMU University Hospital, Munich, Germany
| | - Greta Sawyer
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK
| | - Elisabeth Ehler
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Manfred Wehnert
- Institute of Human Genetics, University of Greifswald, Greifswald, Germany
| | - Li Rao
- Department of Cardiology, West China Hospital of Sichuan University, Chengdu, China
| | - Qiuping Zhang
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK.
| | - Catherine M Shanahan
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London, UK.
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3
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Koppers M, Özkan N, Farías GG. Complex Interactions Between Membrane-Bound Organelles, Biomolecular Condensates and the Cytoskeleton. Front Cell Dev Biol 2020; 8:618733. [PMID: 33409284 PMCID: PMC7779554 DOI: 10.3389/fcell.2020.618733] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 12/03/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane-bound and membraneless organelles/biomolecular condensates ensure compartmentalization into functionally distinct units enabling proper organization of cellular processes. Membrane-bound organelles form dynamic contacts with each other to enable the exchange of molecules and to regulate organelle division and positioning in coordination with the cytoskeleton. Crosstalk between the cytoskeleton and dynamic membrane-bound organelles has more recently also been found to regulate cytoskeletal organization. Interestingly, recent work has revealed that, in addition, the cytoskeleton and membrane-bound organelles interact with cytoplasmic biomolecular condensates. The extent and relevance of these complex interactions are just beginning to emerge but may be important for cytoskeletal organization and organelle transport and remodeling. In this review, we highlight these emerging functions and emphasize the complex interplay of the cytoskeleton with these organelles. The crosstalk between membrane-bound organelles, biomolecular condensates and the cytoskeleton in highly polarized cells such as neurons could play essential roles in neuronal development, function and maintenance.
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Affiliation(s)
| | | | - Ginny G. Farías
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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4
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Chambers DM, Moretti L, Zhang JJ, Cooper SW, Chambers DM, Santangelo PJ, Barker TH. LEM domain-containing protein 3 antagonizes TGFβ-SMAD2/3 signaling in a stiffness-dependent manner in both the nucleus and cytosol. J Biol Chem 2018; 293:15867-15886. [PMID: 30108174 DOI: 10.1074/jbc.ra118.003658] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/31/2018] [Indexed: 12/28/2022] Open
Abstract
Transforming growth factor-β (TGFβ) signaling through SMAD2/3 is an important driver of pathological fibrosis in multiple organ systems. TGFβ signaling and extracellular matrix (ECM) stiffness form an unvirtuous pathological circuit in which matrix stiffness drives activation of latent TGFβ, and TGFβ signaling then drives cellular stress and ECM synthesis. Moreover, ECM stiffness also appears to sensitize cells to exogenously activated TGFβ through unknown mechanisms. Here, using human fibroblasts, we explored the effect of ECM stiffness on a putative inner nuclear membrane protein, LEM domain-containing protein 3 (LEMD3), which is physically connected to the cell's actin cytoskeleton and inhibits TGFβ signaling. We showed that LEMD3-SMAD2/3 interactions are inversely correlated with ECM stiffness and TGFβ-driven luciferase activity and that LEMD3 expression is correlated with the mechanical response of the TGFβ-driven luciferase reporter. We found that actin polymerization but not cellular stress or LEMD3-nuclear-cytoplasmic couplings were necessary for LEMD3-SMAD2/3 interactions. Intriguingly, LEMD3 and SMAD2/3 frequently interacted in the cytosol, and we discovered LEMD3 was proteolytically cleaved into protein fragments. We confirmed that a consensus C-terminal LEMD3 fragment binds SMAD2/3 in a stiffness-dependent manner throughout the cell and is sufficient for antagonizing SMAD2/3 signaling. Using human lung biopsies, we observed that these nuclear and cytosolic interactions are also present in tissue and found that fibrotic tissues exhibit locally diminished and cytoplasmically shifted LEMD3-SMAD2/3 interactions, as noted in vitro Our work reveals novel LEMD3 biology and stiffness-dependent regulation of TGFβ by LEMD3, providing a novel target to antagonize pathological TGFβ signaling.
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Affiliation(s)
- Dwight M Chambers
- From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332
| | - Leandro Moretti
- Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, and
| | - Jennifer J Zhang
- From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332
| | - Spencer W Cooper
- From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332
| | - Davis M Chambers
- the College of Arts and Sciences, Georgia State University, Atlanta, Georgia 30303
| | - Philip J Santangelo
- From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332
| | - Thomas H Barker
- Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, and
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5
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Macro roles for microRNAs in neurodegenerative diseases. Noncoding RNA Res 2018; 3:154-159. [PMID: 30175288 PMCID: PMC6114258 DOI: 10.1016/j.ncrna.2018.07.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 02/07/2023] Open
Abstract
Neurodegenerative diseases (NDs) are typically adult-onset progressive disorders that perturb neuronal function, plasticity and health that arise through a host of one or more genetic and/or environmental factors. Over the last decade, numerous studies have shown that mutations in RNA binding proteins and changes in miRNA profiles within the brain are significantly altered during the progression towards NDs – suggesting miRNAs may be one of these contributing factors. Interestingly, the molecular and cellular functions of miRNAs in NDs is largely understudied and could remain a possible avenue for exploring therapeutic treatments for various NDs. In this review, I describe findings which have implicated miRNAs in various NDs and discuss how future studies focused around miRNA-mediated gene silencing could aid in furthering our understanding of maintaining a healthy brain.
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6
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O'Brien J, Hayder H, Zayed Y, Peng C. Overview of MicroRNA Biogenesis, Mechanisms of Actions, and Circulation. Front Endocrinol (Lausanne) 2018; 9:402. [PMID: 30123182 PMCID: PMC6085463 DOI: 10.3389/fendo.2018.00402] [Citation(s) in RCA: 2668] [Impact Index Per Article: 444.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 06/28/2018] [Indexed: 02/06/2023] Open
Abstract
MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. The majority of miRNAs are transcribed from DNA sequences into primary miRNAs and processed into precursor miRNAs, and finally mature miRNAs. In most cases, miRNAs interact with the 3' untranslated region (3' UTR) of target mRNAs to induce mRNA degradation and translational repression. However, interaction of miRNAs with other regions, including the 5' UTR, coding sequence, and gene promoters, have also been reported. Under certain conditions, miRNAs can also activate translation or regulate transcription. The interaction of miRNAs with their target genes is dynamic and dependent on many factors, such as subcellular location of miRNAs, the abundancy of miRNAs and target mRNAs, and the affinity of miRNA-mRNA interactions. miRNAs can be secreted into extracellular fluids and transported to target cells via vesicles, such as exosomes, or by binding to proteins, including Argonautes. Extracellular miRNAs function as chemical messengers to mediate cell-cell communication. In this review, we provide an update on canonical and non-canonical miRNA biogenesis pathways and various mechanisms underlying miRNA-mediated gene regulations. We also summarize the current knowledge of the dynamics of miRNA action and of the secretion, transfer, and uptake of extracellular miRNAs.
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7
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Abstract
MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. The majority of miRNAs are transcribed from DNA sequences into primary miRNAs and processed into precursor miRNAs, and finally mature miRNAs. In most cases, miRNAs interact with the 3' untranslated region (3' UTR) of target mRNAs to induce mRNA degradation and translational repression. However, interaction of miRNAs with other regions, including the 5' UTR, coding sequence, and gene promoters, have also been reported. Under certain conditions, miRNAs can also activate translation or regulate transcription. The interaction of miRNAs with their target genes is dynamic and dependent on many factors, such as subcellular location of miRNAs, the abundancy of miRNAs and target mRNAs, and the affinity of miRNA-mRNA interactions. miRNAs can be secreted into extracellular fluids and transported to target cells via vesicles, such as exosomes, or by binding to proteins, including Argonautes. Extracellular miRNAs function as chemical messengers to mediate cell-cell communication. In this review, we provide an update on canonical and non-canonical miRNA biogenesis pathways and various mechanisms underlying miRNA-mediated gene regulations. We also summarize the current knowledge of the dynamics of miRNA action and of the secretion, transfer, and uptake of extracellular miRNAs.
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Affiliation(s)
- Jacob O'Brien
- Department of Biology, York University, Toronto, ON, Canada
| | - Heyam Hayder
- Department of Biology, York University, Toronto, ON, Canada
| | - Yara Zayed
- Department of Biology, York University, Toronto, ON, Canada
| | - Chun Peng
- Department of Biology, York University, Toronto, ON, Canada
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8
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Shao J, Gao F, Zhang B, Zhao M, Zhou Y, He J, Ren L, Yao Z, Yang J, Su C, Gao X. Aggregation of SND1 in Stress Granules is Associated with the Microtubule Cytoskeleton During Heat Shock Stimulus. Anat Rec (Hoboken) 2017; 300:2192-2199. [PMID: 28758359 PMCID: PMC5697672 DOI: 10.1002/ar.23642] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/19/2017] [Accepted: 05/30/2017] [Indexed: 12/19/2022]
Abstract
Stress granules (SGs) are dynamic dense structures in the cytoplasm that form in response to a variety of environmental stress stimuli. Staphylococcal nuclease and Tudor domain containing 1 (SND1) is a type of RNA‐binding protein and has been identified as a transcriptional co‐activator. Our previous studies have shown that SND1 is a component of the stress granule, which forms under stress conditions. Here, we observed that SND1 granules were often surrounded by ɑ‐tubulin‐microtubules in 45°C‐treated HeLa cells at 15 min or colocalized with microtubules at 30 or 45 min. Furthermore, Nocodazole‐mediated microtubule depolymerization could significantly affect the efficient recruitment of SND1 proteins to the SGs during heat shock stress. In addition, the 45°C heat shock mediated the enhancement of eIF2α phosphorylation, which was not affected by treatment with Nocodazole, an agent that disrupts the cytoskeleton. The intact microtubule cytoskeletal tracks are important for the efficient assembly of SND1 granules under heat shock stress and may facilitate SND1 shuttling between cytoplasmic RNA foci. Anat Rec, 300:2192–2199, 2017. © 2017 The Authors The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Jie Shao
- Department of Clinical Laboratory, Tianjin Medical University Cancer Institute & Hospital, Tianjin, 300060, People's Republic of China
| | - Fei Gao
- Department of Pediatric Cardiology, Tianjin Children's Hospital, Tianjin, 300070, People's Republic of China
| | - Bingbing Zhang
- Department of Clinical Laboratory, Tianjin Medical University Cancer Institute & Hospital, Tianjin, 300060, People's Republic of China
| | - Meng Zhao
- Department of Clinical Laboratory, Tianjin Medical University Cancer Institute & Hospital, Tianjin, 300060, People's Republic of China
| | - Yunli Zhou
- Department of Clinical Laboratory, Tianjin Medical University Cancer Institute & Hospital, Tianjin, 300060, People's Republic of China
| | - Jinyan He
- Department of Immunology, Basic Medical College, Tianjin Medical University, Tianjin, 300070, People's Republic of China.,Key Laboratory of Educational Ministry of China, Tianjin, 300070, People's Republic of China.,Department of Physiology, Basic Medical College, Tianjin Medical University, Tianjin, 300070, People's Republic of China
| | - Li Ren
- Department of Clinical Laboratory, Tianjin Medical University Cancer Institute & Hospital, Tianjin, 300060, People's Republic of China
| | - Zhi Yao
- Department of Immunology, Basic Medical College, Tianjin Medical University, Tianjin, 300070, People's Republic of China.,Key Laboratory of Educational Ministry of China, Tianjin, 300070, People's Republic of China.,Laboratory of Molecular Immunology, Research Center of Basic Medical Science, Tianjin Medical University, Tianjin, 300070, People's Republic of China
| | - Jie Yang
- Department of Immunology, Basic Medical College, Tianjin Medical University, Tianjin, 300070, People's Republic of China.,Key Laboratory of Educational Ministry of China, Tianjin, 300070, People's Republic of China.,Laboratory of Molecular Immunology, Research Center of Basic Medical Science, Tianjin Medical University, Tianjin, 300070, People's Republic of China
| | - Chao Su
- Department of Immunology, Basic Medical College, Tianjin Medical University, Tianjin, 300070, People's Republic of China.,Key Laboratory of Educational Ministry of China, Tianjin, 300070, People's Republic of China.,Laboratory of Molecular Immunology, Research Center of Basic Medical Science, Tianjin Medical University, Tianjin, 300070, People's Republic of China
| | - Xingjie Gao
- Department of Immunology, Basic Medical College, Tianjin Medical University, Tianjin, 300070, People's Republic of China.,Key Laboratory of Educational Ministry of China, Tianjin, 300070, People's Republic of China.,Laboratory of Molecular Immunology, Research Center of Basic Medical Science, Tianjin Medical University, Tianjin, 300070, People's Republic of China
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9
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Zampedri C, Tinoco-Cuellar M, Carrillo-Rosas S, Diaz-Tellez A, Ramos-Balderas JL, Pelegri F, Maldonado E. Zebrafish P54 RNA helicases are cytoplasmic granule residents that are required for development and stress resilience. Biol Open 2016; 5:1473-1484. [PMID: 27489304 PMCID: PMC5087673 DOI: 10.1242/bio.015826] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Stress granules are cytoplasmic foci that directly respond to the protein synthesis status of the cell. Various environmental insults, such as oxidative stress or extreme heat, block protein synthesis; consequently, mRNA will stall in translation, and stress granules will immediately form and become enriched with mRNAs. P54 DEAD box RNA helicases are components of RNA granules such as P-bodies and stress granules. We studied the expression, in cytoplasmic foci, of both zebrafish P54 RNA helicases (P54a and P54b) during development and found that they are expressed in cytoplasmic granules under both normal conditions and stress conditions. In zebrafish embryos exposed to heat shock, some proportion of P54a and P54b helicases move to larger granules that exhibit the properties of genuine stress granules. Knockdown of P54a and/or P54b in zebrafish embryos produces developmental abnormalities restricted to the posterior trunk; further, these embryos do not form stress granules, and their survival upon exposure to heat-shock conditions is compromised. Our observations fit the model that cells lacking stress granules have no resilience or ability to recover once the stress has ended, indicating that stress granules play an essential role in the way organisms adapt to a changing environment. Summary: Stress granules are formed by mRNAs stalled in translation during stress conditions. P54 RNA helicases from zebrafish reside in cytoplasmic granules and are essential for heat-shock resilience.
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Affiliation(s)
- Cecilia Zampedri
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
| | - Maryana Tinoco-Cuellar
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
| | - Samantha Carrillo-Rosas
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F. México, México, 04510
| | - Abigail Diaz-Tellez
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
| | - Jose Luis Ramos-Balderas
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F. México, México, 04510
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, Wisconsin 53706, USA
| | - Ernesto Maldonado
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
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10
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Rajgor D, Hanley JG, Shanahan CM. Identification of novel nesprin-1 binding partners and cytoplasmic matrin-3 in processing bodies. Mol Biol Cell 2016; 27:3894-3902. [PMID: 27733621 PMCID: PMC5170611 DOI: 10.1091/mbc.e16-06-0346] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 09/20/2016] [Accepted: 10/05/2016] [Indexed: 11/25/2022] Open
Abstract
Several new nesprin-1 binding partners were identified, of which many are well-characterized RNA-binding proteins involved in various forms of nuclear RNA-processing events. Matrin-3 was one such protein identified, and a new cytoplasmic localization for matrin-3 is shown. Nesprins are highly conserved spectrin repeat–containing scaffold proteins predominantly known to function at the nuclear envelope (NE). However, nesprin isoforms are emerging with localizations and scaffolding functions at sites away from the NE, suggesting their functions are more diverse than originally thought. In this study, we combined nesprin-1 coimmunoprecipitations with mass spectrometry to identify novel nesprin-1 binding partners for isoforms that localize to subcellular compartments beyond the NE. We show that one of these interactors, matrin-3 (matr3), localizes to mRNA processing bodies (PBs), where we have previously shown a nesprin-1 isoform to localize. Furthermore, we show that Matr3 is part of PB mRNP complexes, is a regulator of miRNA-mediated gene silencing, and possibly shuttles to stress granules in stressed cells. More importantly, we identify a new C-terminally truncated Matr3 isoform that is likely to be involved in these functions and PB localization. This study highlights several novel nesprin-1 binding partners and a new function and localization for Matr3 in cytoplasmic RNA granules.
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Affiliation(s)
- Dipen Rajgor
- Cardiovascular Division, King's College London, London SE5 9NU, United Kingdom .,Department of Biochemistry, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Jonathan G Hanley
- Department of Biochemistry, University of Bristol, Bristol BS8 1TD, United Kingdom
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11
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Zhang Q, Minaisah RM, Ferraro E, Li C, Porter LJ, Zhou C, Gao F, Zhang J, Rajgor D, Autore F, Shanahan CM, Warren DT. N-terminal nesprin-2 variants regulate β-catenin signalling. Exp Cell Res 2016; 345:168-79. [PMID: 27321956 PMCID: PMC4948682 DOI: 10.1016/j.yexcr.2016.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 01/14/2023]
Abstract
The spatial compartmentalisation of biochemical signalling pathways is essential for cell function. Nesprins are a multi-isomeric family of proteins that have emerged as signalling scaffolds, herein, we investigate the localisation and function of novel nesprin-2 N-terminal variants. We show that these nesprin-2 variants display cell specific distribution and reside in both the cytoplasm and nucleus. Immunofluorescence microscopy revealed that nesprin-2 N-terminal variants colocalised with β-catenin at cell-cell junctions in U2OS cells. Calcium switch assays demonstrated that nesprin-2 and β-catenin are lost from cell-cell junctions in low calcium conditions whereas emerin localisation at the NE remained unaltered, furthermore, an N-terminal fragment of nesprin-2 was sufficient for cell-cell junction localisation and interacted with β-catenin. Disruption of these N-terminal nesprin-2 variants, using siRNA depletion resulted in loss of β-catenin from cell-cell junctions, nuclear accumulation of active β-catenin and augmented β-catenin transcriptional activity. Importantly, we show that U2OS cells lack nesprin-2 giant, suggesting that the N-terminal nesprin-2 variants regulate β-catenin signalling independently of the NE. Together, these data identify N-terminal nesprin-2 variants as novel regulators of β-catenin signalling that tether β-catenin to cell-cell contacts to inhibit β-catenin transcriptional activity.
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Affiliation(s)
- Qiuping Zhang
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Rose-Marie Minaisah
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Elisa Ferraro
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Chen Li
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Lauren J Porter
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Can Zhou
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Fang Gao
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Junyi Zhang
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Dipen Rajgor
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Flavia Autore
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Catherine M Shanahan
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK
| | - Derek T Warren
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
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12
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Specific localization of nesprin-1-α2, the short isoform of nesprin-1 with a KASH domain, in developing, fetal and regenerating muscle, using a new monoclonal antibody. BMC Cell Biol 2016; 17:26. [PMID: 27350129 PMCID: PMC4924313 DOI: 10.1186/s12860-016-0105-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 06/20/2016] [Indexed: 01/25/2023] Open
Abstract
Background Nesprin-1-giant (1008kD) is a protein of the outer nuclear membrane that links nuclei to the actin cytoskeleton via amino-terminal calponin homology domains. The short nesprin-1 isoform, nesprin-1-α2, is present only in skeletal and cardiac muscle and several pathogenic mutations occur within it, but the functions of this short isoform without calponin homology domains are unclear. The aim of this study was to determine mRNA levels and protein localization of nesprin-1-α2 at different stages of muscle development in order to shed light on its functions. Results mRNA levels of all known nesprin-1 isoforms with a KASH domain were determined by quantitative PCR. The mRNA for the 111 kD muscle-specific short isoform, nesprin-1-α2, was not detected in pre-differentiation human myoblasts but was present at significant levels in multinucleate myotubes. We developed a monoclonal antibody against the unique amino-terminal sequence of nesprin-1-α2, enabling specific immunolocalization for the first time. Nesprin-1-α2 protein was undetectable in pre-differentiation myoblasts but appeared at the nuclear rim in post-mitotic, multinucleate myotubes and reached its highest levels in fetal muscle. In muscle from a Duchenne muscular dystrophy biopsy, nesprin-1-α2 protein was detected mainly in regenerating fibres expressing neonatal myosin. Nesprin-1-giant was present at all developmental stages, but was also highest in fetal and regenerating fibres. In fetal muscle, both isoforms were present in the cytoplasm, as well as at the nuclear rim. A pathogenic early stop codon (E7854X) in nesprin-1 caused reduced mRNA levels and loss of protein levels of both nesprin-1-giant and (unexpectedly) nesprin-1-α2, but did not affect myogenesis in vitro. Conclusions Nesprin-1-α2 mRNA and protein expression is switched on during myogenesis, alongside other known markers of muscle differentiation. The results show that nesprin-1-α2 is dynamically controlled and may be involved in some process occurring during early myofibre formation, such as re-positioning of nuclei.
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Abstract
Nesprins are a family of multi-isomeric scaffolding proteins that were originally identified at the nuclear envelope (NE), where they bind to lamin A/C, emerin, and SUN-domain containing proteins, to form the LInker of Nucleoskeleton-and-Cytoskeleton (LINC) complex that connects the NE to the actin cytoskeleton. However, nesprin genes also give rise to a variety of tissue-specific variants of different sizes with potential roles beyond the NE. These variants are generated through alternative initiation, termination, and splicing, which makes nesprin biology very complex to study due to the difficulty in generating specific antibodies and/or short interfering RNAs (siRNA) to particular isoforms. In order to distinguish genuine nesprin variants and eliminate confusion with degradation products of larger nesprin isoforms, in this chapter we discuss methods including 5' and 3' Rapid Amplification of cDNA Ends (RACE) and RT-PCR in combination with EST database searching, for identifying and validating putative nesprin isoforms. This information is essential to allow a better understanding of nesprin functions in different cell types.
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14
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Myat MM, Rashmi RN, Manna D, Xu N, Patel U, Galiano M, Zielinski K, Lam A, Welte MA. Drosophila KASH-domain protein Klarsicht regulates microtubule stability and integrin receptor localization during collective cell migration. Dev Biol 2015; 407:103-14. [PMID: 26247519 PMCID: PMC4785808 DOI: 10.1016/j.ydbio.2015.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 07/29/2015] [Accepted: 08/01/2015] [Indexed: 12/28/2022]
Abstract
During collective migration of the Drosophila embryonic salivary gland, cells rearrange to form a tube of a distinct shape and size. Here, we report a novel role for the Drosophila Klarsicht-Anc-Syne Homology (KASH) domain protein Klarsicht (Klar) in the regulation of microtubule (MT) stability and integrin receptor localization during salivary gland migration. In wild-type salivary glands, MTs became progressively stabilized as gland migration progressed. In embryos specifically lacking the KASH domain containing isoforms of Klar, salivary gland cells failed to rearrange and migrate, and these defects were accompanied by decreased MT stability and altered integrin receptor localization. In muscles and photoreceptors, KASH isoforms of Klar work together with Klaroid (Koi), a SUN domain protein, to position nuclei; however, loss of Koi had no effect on salivary gland migration, suggesting that Klar controls gland migration through novel interactors. The disrupted cell rearrangement and integrin localization observed in klar mutants could be mimicked by overexpressing Spastin (Spas), a MT severing protein, in otherwise wild-type salivary glands. In turn, promoting MT stability by reducing spas gene dosage in klar mutant embryos rescued the integrin localization, cell rearrangement and gland migration defects. Klar genetically interacts with the Rho1 small GTPase in salivary gland migration and is required for the subcellular localization of Rho1. We also show that Klar binds tubulin directly in vitro. Our studies provide the first evidence that a KASH-domain protein regulates the MT cytoskeleton and integrin localization during collective cell migration.
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Affiliation(s)
- M M Myat
- Department of Biology, Medgar Evers College - CUNY, 1638 Bedford Avenue, Brooklyn, NY 11225, USA.
| | - R N Rashmi
- Department of Biology, Medgar Evers College - CUNY, 1638 Bedford Avenue, Brooklyn, NY 11225, USA
| | - D Manna
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - N Xu
- Department of Natural Sciences, LaGuardia Community College - CUNY, Long Island City, NY 11101, USA
| | - U Patel
- Department of Biology, Medgar Evers College - CUNY, 1638 Bedford Avenue, Brooklyn, NY 11225, USA
| | - M Galiano
- Department of Biology, Medgar Evers College - CUNY, 1638 Bedford Avenue, Brooklyn, NY 11225, USA
| | - K Zielinski
- Department of Biology, Medgar Evers College - CUNY, 1638 Bedford Avenue, Brooklyn, NY 11225, USA
| | - A Lam
- Department of Biology, Medgar Evers College - CUNY, 1638 Bedford Avenue, Brooklyn, NY 11225, USA
| | - M A Welte
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
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15
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Corcoran JA, McCormick C. Viral activation of stress-regulated Rho-GTPase signaling pathway disrupts sites of mRNA degradation to influence cellular gene expression. Small GTPases 2015; 6:178-85. [PMID: 26480288 PMCID: PMC4905259 DOI: 10.1080/21541248.2015.1093068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 09/07/2015] [Accepted: 09/08/2015] [Indexed: 01/09/2023] Open
Abstract
Viruses are useful tools that often reveal previously unrecognized levels of control within a cell. By studying the oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV), we discovered a new signaling axis in endothelial cells (ECs) that links actin cytoskeleton dynamics to post-transcriptional control of gene expression. Translational repression and rapid decay of mRNAs containing AU-rich elements (AREs) occurs in cytoplasmic RNA granules known as processing bodies (PBs). Rho-GTPase activity influences PB dynamics but mechanistic details remain obscure. We have previously shown that the KSHV Kaposin B protein blocks the degradation of ARE-mRNAs that encode potent cytokines and angiogenic factors, at least in part by preventing PB formation. Moreover, Kaposin B is sufficient to cause marked alterations in endothelial cell physiology including the formation of long parallel actin stress fibers and accelerated migration and angiogenic phenotypes. All of these phenotypes depend on Kaposin B-mediated activation of a non-canonical signaling pathway comprising the stress-inducible kinase MK2, hsp27, p115RhoGEF and RhoA. Accelerated endothelial cell migration and angiogenesis depends on the subsequent activation of the RhoA-dependent kinase ROCK, but PB disruption is ROCK-independent. In this Commentary, we discuss implications of the activation of this signaling axis, and propose mechanistic links between RhoA activation and PB dynamics.
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Affiliation(s)
- Jennifer A Corcoran
- Department of Microbiology and Immunology; Dalhousie University; Halifax NS, Canada
| | - Craig McCormick
- Department of Microbiology and Immunology; Dalhousie University; Halifax NS, Canada
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16
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Kim HJ, Choi WJ, Lee CH. Phosphorylation and Reorganization of Keratin Networks: Implications for Carcinogenesis and Epithelial Mesenchymal Transition. Biomol Ther (Seoul) 2015; 23:301-12. [PMID: 26157545 PMCID: PMC4489823 DOI: 10.4062/biomolther.2015.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 04/30/2015] [Accepted: 05/04/2015] [Indexed: 12/15/2022] Open
Abstract
Metastasis is one of hallmarks of cancer and a major cause of cancer death. Combatting metastasis is highly challenging. To overcome these difficulties, researchers have focused on physical properties of metastatic cancer cells. Metastatic cancer cells from patients are softer than benign cancer or normal cells. Changes of viscoelasticity of cancer cells are related to the keratin network. Unexpectedly, keratin network is dynamic and regulation of keratin network is important to the metastasis of cancer. Keratin is composed of heteropolymer of type I and II. Keratin connects from the plasma membrane to nucleus. Several proteins including kinases, and protein phosphatases bind to keratin intermediate filaments. Several endogenous compounds or toxic compounds induce phosphorylation and reorganization of keratin network in cancer cells, leading to increased migration. Continuous phosphorylation of keratin results in loss of keratin, which is one of the features of epithelial mesenchymal transition (EMT). Therefore, several proteins involved in phosphorylation and reorganization of keratin also have a role in EMT. It is likely that compounds controlling phosphorylation and reorganization of keratin are potential candidates for combating EMT and metastasis.
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Affiliation(s)
- Hyun Ji Kim
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Won Jun Choi
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Chang Hoon Lee
- BK21PLUS R-FIND team, College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
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Razafsky D, Hodzic D. Nuclear envelope: positioning nuclei and organizing synapses. Curr Opin Cell Biol 2015; 34:84-93. [PMID: 26079712 DOI: 10.1016/j.ceb.2015.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022]
Abstract
The nuclear envelope plays an essential role in nuclear positioning within cells and tissues. This review highlights advances in understanding the mechanisms of nuclear positioning during skeletal muscle and central nervous system development. New findings, particularly about A-type lamins and Nesprin1, may link nuclear envelope integrity to synaptic integrity. Thus synaptic defects, rather than nuclear mispositioning, may underlie human pathologies associated with mutations of nuclear envelope proteins.
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Affiliation(s)
- David Razafsky
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
| | - Didier Hodzic
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA.
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18
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Welte MA. As the fat flies: The dynamic lipid droplets of Drosophila embryos. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1156-85. [PMID: 25882628 DOI: 10.1016/j.bbalip.2015.04.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 03/31/2015] [Accepted: 04/06/2015] [Indexed: 01/09/2023]
Abstract
Research into lipid droplets is rapidly expanding, and new cellular and organismal roles for these lipid-storage organelles are continually being discovered. The early Drosophila embryo is particularly well suited for addressing certain questions in lipid-droplet biology and combines technical advantages with unique biological phenomena. This review summarizes key features of this experimental system and the techniques available to study it, in order to make it accessible to researchers outside this field. It then describes the two topics most heavily studied in this system, lipid-droplet motility and protein sequestration on droplets, discusses what is known about the molecular players involved, points to open questions, and compares the results from Drosophila embryo studies to what it is known about lipid droplets in other systems.
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Affiliation(s)
- Michael A Welte
- Department of Biology University of Rochester, RC Box 270211, 317 Hutchison Hall, Rochester, NY 14627, USA.
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19
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Razafsky D, Hodzic D. A variant of Nesprin1 giant devoid of KASH domain underlies the molecular etiology of autosomal recessive cerebellar ataxia type I. Neurobiol Dis 2015; 78:57-67. [PMID: 25843669 DOI: 10.1016/j.nbd.2015.03.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 03/24/2015] [Accepted: 03/26/2015] [Indexed: 12/21/2022] Open
Abstract
Nonsense mutations across the whole coding sequence of Syne1/Nesprin1 have been linked to autosomal recessive cerebellar ataxia Type I (ARCA1). However, nothing is known about the molecular etiology of this late-onset debilitating pathology. In this work, we report that Nesprin1 giant is specifically expressed in CNS tissues. We also identified a CNS-specific splicing event that leads to the abundant expression of a KASH-LESS variant of Nesprin1 giant (KLNes1g) in the cerebellum. KLNes1g displayed a noncanonical localization at glomeruli of cerebellar mossy fibers whereas Nesprin2 exclusively decorated the nuclear envelope of all cerebellar neurons. In immunogold electron microscopy, KLNes1g colocalized both with synaptic vesicles within mossy fibers and with dendritic membranes of cerebellar granule neurons. We further identified vesicle- and membrane-associated proteins in KLNes1g immunoprecipitates. Together, our results suggest that the loss of function of KLNes1g resulting from Nesprin1 nonsense mutations underlies the molecular etiology of ARCA1.
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Affiliation(s)
- David Razafsky
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid, St Louis, MO 63110, USA
| | - Didier Hodzic
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid, St Louis, MO 63110, USA.
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Chang W, Worman HJ, Gundersen GG. Accessorizing and anchoring the LINC complex for multifunctionality. ACTA ACUST UNITED AC 2015; 208:11-22. [PMID: 25559183 PMCID: PMC4284225 DOI: 10.1083/jcb.201409047] [Citation(s) in RCA: 210] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex, composed of outer and inner nuclear membrane Klarsicht, ANC-1, and Syne homology (KASH) and Sad1 and UNC-84 (SUN) proteins, respectively, connects the nucleus to cytoskeletal filaments and performs diverse functions including nuclear positioning, mechanotransduction, and meiotic chromosome movements. Recent studies have shed light on the source of this diversity by identifying factors associated with the complex that endow specific functions as well as those that differentially anchor the complex within the nucleus. Additional diversity may be provided by accessory factors that reorganize the complex into higher-ordered arrays. As core components of the LINC complex are associated with several diseases, understanding the role of accessory and anchoring proteins could provide insights into pathogenic mechanisms.
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Affiliation(s)
- Wakam Chang
- Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Howard J Worman
- Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032 Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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21
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Burn KM, Shimada Y, Ayers K, Vemuganti S, Lu F, Hudson AM, Cooley L. Somatic insulin signaling regulates a germline starvation response in Drosophila egg chambers. Dev Biol 2015; 398:206-17. [PMID: 25481758 PMCID: PMC4340711 DOI: 10.1016/j.ydbio.2014.11.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/17/2014] [Accepted: 11/22/2014] [Indexed: 12/31/2022]
Abstract
Egg chambers from starved Drosophila females contain large aggregates of processing (P) bodies and cortically enriched microtubules. As this response to starvation is rapidly reversed upon re-feeding females or culturing egg chambers with exogenous bovine insulin, we examined the role of endogenous insulin signaling in mediating the starvation response. We found that systemic Drosophila insulin-like peptides (dILPs) activate the insulin pathway in follicle cells, which then regulate both microtubule and P body organization in the underlying germline cells. This organization is modulated by the motor proteins Dynein and Kinesin. Dynein activity is required for microtubule and P body organization during starvation, while Kinesin activity is required during nutrient-rich conditions. Blocking the ability of egg chambers to form P body aggregates in response to starvation correlated with reduced progeny survival. These data suggest a potential mechanism to maximize fecundity even during periods of poor nutrient availability, by mounting a protective response in immature egg chambers.
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Affiliation(s)
- K Mahala Burn
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Yuko Shimada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Seinou-tou D301, Tennoudai 1-1-1, Tsukuba,, Ibaraki 305-8572, Japan
| | - Kathleen Ayers
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Soumya Vemuganti
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Feiyue Lu
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Andrew M Hudson
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Lynn Cooley
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States; Department of Molecular, Cellular and Developmental Biology, Yale University, 260 Prospect Street, New Haven, CT 06510, United States.
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22
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Corcoran JA, Johnston BP, McCormick C. Viral activation of MK2-hsp27-p115RhoGEF-RhoA signaling axis causes cytoskeletal rearrangements, p-body disruption and ARE-mRNA stabilization. PLoS Pathog 2015; 11:e1004597. [PMID: 25569678 PMCID: PMC4287613 DOI: 10.1371/journal.ppat.1004597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/02/2014] [Indexed: 11/30/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious cause of several AIDS-related cancers, including the endothelial cell (EC) neoplasm Kaposi's sarcoma (KS). KSHV-infected ECs secrete abundant host-derived pro-inflammatory molecules and angiogenic factors that contribute to tumorigenesis. The precise contributions of viral gene products to this secretory phenotype remain to be elucidated, but there is emerging evidence for post-transcriptional regulation. The Kaposin B (KapB) protein is thought to contribute to the secretory phenotype in infected cells by binding and activating the stress-responsive kinase MK2, thereby selectively blocking decay of AU-rich mRNAs (ARE-mRNAs) encoding pro-inflammatory cytokines and angiogenic factors. Processing bodies (PBs) are cytoplasmic ribonucleoprotein foci in which ARE-mRNAs normally undergo rapid 5′ to 3′ decay. Here, we demonstrate that PB dispersion is a feature of latent KSHV infection, which is dependent on kaposin protein expression. KapB is sufficient to disperse PBs, and KapB-mediated ARE-mRNA stabilization could be partially reversed by treatments that restore PBs. Using a combination of genetic and chemical approaches we provide evidence that KapB-mediated PB dispersion is dependent on activation of a non-canonical Rho-GTPase signaling axis involving MK2, hsp27, p115RhoGEF and RhoA. PB dispersion in latently infected cells is likewise dependent on p115RhoGEF. In addition to PB dispersion, KapB-mediated RhoA activation in primary ECs caused actin stress fiber formation, increased cell motility and angiogenesis; these effects were dependent on the activity of the RhoA substrate kinases ROCK1/2. By contrast, KapB-mediated PB dispersion occurred in a ROCK1/2-independent manner. Taken together, these observations position KapB as a key contributor to viral reprogramming of ECs, capable of eliciting many of the phenotypes characteristic of KS tumor cells, and strongly contributing to the post-transcriptional control of EC gene expression and secretion. We have only scratched the surface in understanding how viruses control host gene expression. Several viruses disrupt important sites of post-transcriptional control of gene expression known as processing bodies (PBs), but underlying regulatory mechanisms and biological relevance remain poorly understood in most cases. Our study shows that the Kaposin B (KapB) protein of Kaposi's sarcoma (KS)-associated herpesvirus, known to block the degradation of a class of labile host mRNAs, does so by constitutively activating a signaling axis involving MK2, hsp27, p115RhoGEF and RhoA, thereby dispersing PBs. Thus, PB disruption may support the secretion of host pro-inflammatory cytokines and angiogenic factors that underlies KS tumor formation. Furthermore, by activating RhoA, KapB also causes cytoskeletal rearrangements, accelerated cell migration and angiogenesis in an endothelial cell model. Our findings position KapB as a key contributor to viral reprogramming of endothelial cells.
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Affiliation(s)
- Jennifer A. Corcoran
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Beatrice Hunter Cancer Research Institute, Halifax, Nova Scotia, Canada
| | - Benjamin P. Johnston
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Beatrice Hunter Cancer Research Institute, Halifax, Nova Scotia, Canada
| | - Craig McCormick
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Beatrice Hunter Cancer Research Institute, Halifax, Nova Scotia, Canada
- * E-mail:
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Abstract
In eukaryotic cells, non-translating mRNAs can accumulate into cytoplasmic mRNP (messenger ribonucleoprotein) granules such as P-bodies (processing bodies) and SGs (stress granules). P-bodies contain the mRNA decay and translational repression machineries and are ubiquitously expressed in mammalian cells and lower eukaryote species including Saccharomyces cerevisiae, Drosophila melanogaster and Caenorhabditis elegans. In contrast, SGs are only detected during cellular stress when translation is inhibited and form from aggregates of stalled pre-initiation complexes. SGs and P-bodies are related to NGs (neuronal granules), which are essential in the localization and control of mRNAs in neurons. Importantly, RNA granules are linked to the cytoskeleton, which plays an important role in mediating many of their dynamic properties. In the present review, we discuss how P-bodies, SGs and NGs are linked to cytoskeletal networks and the importance of these linkages in maintaining localization of their RNA cargoes.
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