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Lu SHA, Wu YH, Su LY, Hsu ZT, Weng TH, Wang HY, Yu C, Hsu PWC, Tsai SY. Cardiac myofibrillogenesis is spatiotemporally modulated by the molecular chaperone UNC45B. Stem Cell Reports 2023:S2213-6711(23)00184-4. [PMID: 37295424 PMCID: PMC10362501 DOI: 10.1016/j.stemcr.2023.05.006] [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: 10/26/2022] [Revised: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 06/12/2023] Open
Abstract
Sarcomeres are fundamental to cardiac muscle contraction. Their impairment can elicit cardiomyopathies, leading causes of death worldwide. However, the molecular mechanism underlying sarcomere assembly remains obscure. We used human embryonic stem cell (hESC)-derived cardiomyocytes (CMs) to reveal stepwise spatiotemporal regulation of core cardiac myofibrillogenesis-associated proteins. We found that the molecular chaperone UNC45B is highly co-expressed with KINDLIN2 (KIND2), a marker of protocostameres, and later its distribution overlaps with that of muscle myosin MYH6. UNC45B-knockout CMs display essentially no contractility. Our phenotypic analyses further reveal that (1) binding of Z line anchor protein ACTN2 to protocostameres is perturbed because of impaired protocostamere formation, resulting in ACTN2 accumulation; (2) F-ACTIN polymerization is suppressed; and (3) MYH6 becomes degraded, so it cannot replace non-muscle myosin MYH10. Our mechanistic study demonstrates that UNC45B mediates protocostamere formation by regulating KIND2 expression. Thus, we show that UNC45B modulates cardiac myofibrillogenesis by interacting spatiotemporally with various proteins.
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Affiliation(s)
- Serena Huei-An Lu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Hsuan Wu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Liang-Yu Su
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Zi-Ting Hsu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Tzu-Han Weng
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Hsin-Yu Wang
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Chiao Yu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Paul Wei-Che Hsu
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli County 350, Taiwan
| | - Su-Yi Tsai
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei 10617, Taiwan; Genome and Systems Biology Degree Program, National Taiwan University, Taipei 10617, Taiwan.
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Odunuga OO, Oberhauser AF. Beyond Chaperoning: UCS Proteins Emerge as Regulators of Myosin-Mediated Cellular Processes. Subcell Biochem 2023; 101:189-211. [PMID: 36520308 DOI: 10.1007/978-3-031-14740-1_7] [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] [Indexed: 06/17/2023]
Abstract
The UCS (UNC-45/CRO1/She4p) family of proteins has emerged as chaperones specific for the folding, assembly, and function of myosin. UCS proteins participate in various myosin-dependent cellular processes including myofibril organization and muscle functions, cell differentiation, striated muscle development, cytokinesis, and endocytosis. Mutations in the genes that code for UCS proteins cause serious defects in myosin-dependent cellular processes. UCS proteins that contain an N-terminal tetratricopeptide repeat (TPR) domain are called UNC-45. Vertebrates usually possess two variants of UNC-45, the ubiquitous general-cell UNC-45 (UNC-45A) and the striated muscle UNC-45 (UNC-45B), which is exclusively expressed in skeletal and cardiac muscles. Except for the TPR domain in UNC-45, UCS proteins comprise of several irregular armadillo (ARM) repeats that are organized into a central domain, a neck region, and the canonical C-terminal UCS domain that functions as the chaperoning module. With or without TPR, UCS proteins form linear oligomers that serve as scaffolds that mediate myosin folding, organization into myofibrils, repair, and motility. This chapter reviews emerging functions of these proteins with a focus on UNC-45 as a dedicated chaperone for folding, assembly, and function of myosin at protein and potentially gene levels. Recent experimental evidences strongly support UNC-45 as an absolute regulator of myosin, with each domain of the chaperone playing different but complementary roles during the folding, assembly, and function of myosin, as well as recruiting Hsp90 as a co-chaperone to optimize key steps. It is becoming increasingly clear that UNC-45 also regulates the transcription of several genes involved in myosin-dependent cellular processes.
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Affiliation(s)
- Odutayo O Odunuga
- Department of Chemistry and Biochemistry, Stephen F. Austin State University, Nacogdoches, TX, USA.
| | - Andres F Oberhauser
- Department of Neuroscience, Cell Biology, & Anatomy, The University of Texas Medical Branch, Galveston, TX, USA.
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Johnson CA, Behbehani R, Buss F. Unconventional Myosins from Caenorhabditis elegans as a Probe to Study Human Orthologues. Biomolecules 2022; 12:biom12121889. [PMID: 36551317 PMCID: PMC9775386 DOI: 10.3390/biom12121889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Unconventional myosins are a superfamily of actin-based motor proteins that perform a number of roles in fundamental cellular processes, including (but not limited to) intracellular trafficking, cell motility, endocytosis, exocytosis and cytokinesis. 40 myosins genes have been identified in humans, which belong to different 12 classes based on their domain structure and organisation. These genes are widely expressed in different tissues, and mutations leading to loss of function are associated with a wide variety of pathologies while over-expression often results in cancer. Caenorhabditis elegans (C. elegans) is a small, free-living, non-parasitic nematode. ~38% of the genome of C. elegans has predicted orthologues in the human genome, making it a valuable tool to study the function of human counterparts and human diseases. To date, 8 unconventional myosin genes have been identified in the nematode, from 6 different classes with high homology to human paralogues. The hum-1 and hum-5 (heavy chain of an unconventional myosin) genes encode myosin of class I, hum-2 of class V, hum-3 and hum-8 of class VI, hum-6 of class VII and hum-7 of class IX. The hum-4 gene encodes a high molecular mass myosin (307 kDa) that is one of the most highly divergent myosins and is a member of class XII. Mutations in many of the human orthologues are lethal, indicating their essential properties. However, a functional characterisation for many of these genes in C. elegans has not yet been performed. This article reviews the current knowledge of unconventional myosin genes in C. elegans and explores the potential use of the nematode to study the function and regulation of myosin motors to provide valuable insights into their role in diseases.
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Piper PW, Scott JE, Millson SH. UCS Chaperone Folding of the Myosin Head: A Function That Evolved before Animals and Fungi Diverged from a Common Ancestor More than a Billion Years Ago. Biomolecules 2022; 12:biom12081028. [PMID: 35892339 PMCID: PMC9331494 DOI: 10.3390/biom12081028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 12/04/2022] Open
Abstract
The folding of the myosin head often requires a UCS (Unc45, Cro1, She4) domain-containing chaperone. Worms, flies, and fungi have just a single UCS protein. Vertebrates have two; one (Unc45A) which functions primarily in non-muscle cells and another (Unc45B) that is essential for establishing and maintaining the contractile apparatus of cardiac and skeletal muscles. The domain structure of these proteins suggests that the UCS function evolved before animals and fungi diverged from a common ancestor more than a billion years ago. UCS proteins of metazoans and apicomplexan parasites possess a tetratricopeptide repeat (TPR), a domain for direct binding of the Hsp70/Hsp90 chaperones. This, however, is absent in the UCS proteins of fungi and largely nonessential for the UCS protein function in Caenorhabditis elegans and zebrafish. The latter part of this review focusses on the TPR-deficient UCS proteins of fungi. While these are reasonably well studied in yeasts, there is little precise information as to how they might engage in interactions with the Hsp70/Hsp90 chaperones or might assist in myosin operations during the hyphal growth of filamentous fungi.
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Affiliation(s)
- Peter William Piper
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
- Correspondence: (P.W.P.); (S.H.M.)
| | | | - Stefan Heber Millson
- School of Life Sciences, University of Lincoln, Lincoln LN6 7DL, UK;
- Correspondence: (P.W.P.); (S.H.M.)
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5
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Habicht J, Mooneyham A, Hoshino A, Shetty M, Zhang X, Emmings E, Yang Q, Coombes C, Gardner MK, Bazzaro M. UNC-45A breaks the microtubule lattice independently of its effects on non-muscle myosin II. J Cell Sci 2021; 134:jcs.248815. [PMID: 33262310 DOI: 10.1242/jcs.248815] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 11/18/2020] [Indexed: 12/13/2022] Open
Abstract
In invertebrates, UNC-45 regulates myosin stability and functions. Vertebrates have two distinct isoforms of the protein: UNC-45B, expressed in muscle cells only, and UNC-45A, expressed in all cells and implicated in regulating both non-muscle myosin II (NMII)- and microtubule (MT)-associated functions. Here, we show that, in vitro and in human and rat cells, UNC-45A binds to the MT lattice, leading to MT bending, breakage and depolymerization. Furthermore, we show that UNC-45A destabilizes MTs independent of its C-terminal NMII-binding domain and even in the presence of the NMII inhibitor blebbistatin. These findings identified UNC-45A as a novel type of MT-severing protein with a dual non-mutually exclusive role in regulating NMII activity and MT stability. Because many human diseases, from cancer to neurodegenerative diseases, are caused by or associated with deregulation of MT stability, our findings have profound implications in the biology of MTs, as well as the biology of human diseases and possible therapeutic implications for their treatment.This article has an associated First Person interview with the joint first authors of the paper.
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Affiliation(s)
- Juri Habicht
- Bradenburg Medical School - Theodor Fontane, Neuruppin 16816, Germany.,Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ashley Mooneyham
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, MN 55455, USA
| | - Asumi Hoshino
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mihir Shetty
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, MN 55455, USA
| | - Xiaonan Zhang
- Bradenburg Medical School - Theodor Fontane, Neuruppin 16816, Germany.,Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, MN 55455, USA
| | - Edith Emmings
- Bradenburg Medical School - Theodor Fontane, Neuruppin 16816, Germany
| | - Qing Yang
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Courtney Coombes
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Melissa K Gardner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Martina Bazzaro
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, MN 55455, USA
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6
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Donkervoort S, Kutzner CE, Hu Y, Lornage X, Rendu J, Stojkovic T, Baets J, Neuhaus SB, Tanboon J, Maroofian R, Bolduc V, Mroczek M, Conijn S, Kuntz NL, Töpf A, Monges S, Lubieniecki F, McCarty RM, Chao KR, Governali S, Böhm J, Boonyapisit K, Malfatti E, Sangruchi T, Horkayne-Szakaly I, Hedberg-Oldfors C, Efthymiou S, Noguchi S, Djeddi S, Iida A, di Rosa G, Fiorillo C, Salpietro V, Darin N, Fauré J, Houlden H, Oldfors A, Nishino I, de Ridder W, Straub V, Pokrzywa W, Laporte J, Foley AR, Romero NB, Ottenheijm C, Hoppe T, Bönnemann CG. Pathogenic Variants in the Myosin Chaperone UNC-45B Cause Progressive Myopathy with Eccentric Cores. Am J Hum Genet 2020; 107:1078-1095. [PMID: 33217308 DOI: 10.1016/j.ajhg.2020.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 11/03/2020] [Indexed: 01/03/2023] Open
Abstract
The myosin-directed chaperone UNC-45B is essential for sarcomeric organization and muscle function from Caenorhabditis elegans to humans. The pathological impact of UNC-45B in muscle disease remained elusive. We report ten individuals with bi-allelic variants in UNC45B who exhibit childhood-onset progressive muscle weakness. We identified a common UNC45B variant that acts as a complex hypomorph splice variant. Purified UNC-45B mutants showed changes in folding and solubility. In situ localization studies further demonstrated reduced expression of mutant UNC-45B in muscle combined with abnormal localization away from the A-band towards the Z-disk of the sarcomere. The physiological relevance of these observations was investigated in C. elegans by transgenic expression of conserved UNC-45 missense variants, which showed impaired myosin binding for one and defective muscle function for three. Together, our results demonstrate that UNC-45B impairment manifests as a chaperonopathy with progressive muscle pathology, which discovers the previously unknown conserved role of UNC-45B in myofibrillar organization.
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Affiliation(s)
- Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Carl E Kutzner
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
| | - Ying Hu
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xavière Lornage
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U1258, CNRS UMR7104, Université de Strasbourg, BP 10142, 67404 Illkirch, France
| | - John Rendu
- Centre Hospitalier Universitaire de Grenoble Alpes, Biochimie Génétique et Moléculaire, Grenoble 38000, France; Grenoble Institut des Neurosciences-INSERM U1216 UGA, Grenoble 38000, France
| | - Tanya Stojkovic
- Centre de Référence des Maladies Neuromusculaires Nord/Est/Ile de France, Institut de Myologie, GHU La Pitié-Salpêtrière, Sorbonne Université, AP-HP, 75013 Paris, France
| | - Jonathan Baets
- Faculty of Medicine, University of Antwerp, 2610 Antwerp, Belgium; Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, 2610 Antwerp, Belgium; Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, 2650 Antwerp, Belgium
| | - Sarah B Neuhaus
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jantima Tanboon
- Department of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, 10700 Bangkok, Thailand; Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 187-8502 Tokyo, Japan
| | - Reza Maroofian
- Department of Neuromuscular Disorders, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Véronique Bolduc
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Magdalena Mroczek
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Stefan Conijn
- Department of Physiology, Amsterdam UMC (location VUmc), 1081 HZ Amsterdam, the Netherlands
| | - Nancy L Kuntz
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Soledad Monges
- Servicio de Neurología y Servicio de Patologia, Hospital de Pediatría Garrahan, C1245 AAM Buenos Aires, Argentina
| | - Fabiana Lubieniecki
- Servicio de Neurología y Servicio de Patologia, Hospital de Pediatría Garrahan, C1245 AAM Buenos Aires, Argentina
| | - Riley M McCarty
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Katherine R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Serena Governali
- Department of Physiology, Amsterdam UMC (location VUmc), 1081 HZ Amsterdam, the Netherlands
| | - Johann Böhm
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U1258, CNRS UMR7104, Université de Strasbourg, BP 10142, 67404 Illkirch, France
| | - Kanokwan Boonyapisit
- Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol, University, 10700 Bangkok, Thailand
| | - Edoardo Malfatti
- Neurology Department, Raymond-Poincaré teaching hospital, centre de référence des maladies neuromusculaires Nord/Est/Ile-de-France, AP-HP, 92380 Garches, France
| | - Tumtip Sangruchi
- Department of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, 10700 Bangkok, Thailand
| | | | - Carola Hedberg-Oldfors
- Department of Laboratory Medicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 187-8502 Tokyo, Japan; Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Psychiatry, 187-8551 Tokyo, Japan
| | - Sarah Djeddi
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U1258, CNRS UMR7104, Université de Strasbourg, BP 10142, 67404 Illkirch, France
| | - Aritoshi Iida
- Department of Clinical Genome Analysis, Medical Genome Center, National Center of Neurology and Psychiatry, 187-8551 Tokyo, Japan
| | - Gabriella di Rosa
- Division of Child Neurology and Psychiatry, Department of the Adult and Developmental Age Human Pathology, University of Messina, Messina 98125, Italy
| | - Chiara Fiorillo
- Pediatric Neurology and Muscular Diseases Unit, G. Gaslini Institute, 16147 Genoa, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
| | - Vincenzo Salpietro
- Pediatric Neurology and Muscular Diseases Unit, G. Gaslini Institute, 16147 Genoa, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
| | - Niklas Darin
- Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, 41650 Gothenburg, Sweden
| | - Julien Fauré
- Centre Hospitalier Universitaire de Grenoble Alpes, Biochimie Génétique et Moléculaire, Grenoble 38000, France; Grenoble Institut des Neurosciences-INSERM U1216 UGA, Grenoble 38000, France
| | - Henry Houlden
- Department of Neuromuscular Disorders, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Anders Oldfors
- Department of Laboratory Medicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 187-8502 Tokyo, Japan; Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Psychiatry, 187-8551 Tokyo, Japan; Department of Clinical Genome Analysis, Medical Genome Center, National Center of Neurology and Psychiatry, 187-8551 Tokyo, Japan
| | - Willem de Ridder
- Faculty of Medicine, University of Antwerp, 2610 Antwerp, Belgium; Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, 2610 Antwerp, Belgium; Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, 2650 Antwerp, Belgium
| | - Volker Straub
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK; Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE7 7DN, UK
| | - Wojciech Pokrzywa
- Laboratory of Protein Metabolism in Development and Aging, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Jocelyn Laporte
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U1258, CNRS UMR7104, Université de Strasbourg, BP 10142, 67404 Illkirch, France
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Norma B Romero
- Centre de Référence des Maladies Neuromusculaires Nord/Est/Ile de France, Institut de Myologie, GHU La Pitié-Salpêtrière, Sorbonne Université, AP-HP, 75013 Paris, France; Université Sorbonne, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, GH Pitié-Salpêtrière, 75651 Paris, France; Neuromuscular Morphology Unit, Myology Institute, GHU Pitié-Salpêtrière, 75013 Paris, France
| | - Coen Ottenheijm
- Department of Physiology, Amsterdam UMC (location VUmc), 1081 HZ Amsterdam, the Netherlands; Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85718, USA
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Under construction: The dynamic assembly, maintenance, and degradation of the cardiac sarcomere. J Mol Cell Cardiol 2020; 148:89-102. [PMID: 32920010 DOI: 10.1016/j.yjmcc.2020.08.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/20/2020] [Accepted: 08/22/2020] [Indexed: 12/11/2022]
Abstract
The sarcomere is the basic contractile unit of striated muscle and is a highly ordered protein complex with the actin and myosin filaments at its core. Assembling the sarcomere constituents into this organized structure in development, and with muscle growth as new sarcomeres are built, is a complex process coordinated by numerous factors. Once assembled, the sarcomere requires constant maintenance as its continuous contraction is accompanied by elevated mechanical, thermal, and oxidative stress, which predispose proteins to misfolding and toxic aggregation. To prevent protein misfolding and maintain sarcomere integrity, the sarcomere is monitored by an assortment of protein quality control (PQC) mechanisms. The need for effective PQC is heightened in cardiomyocytes which are terminally differentiated and must survive for many years while preserving optimal mechanical output. To prevent toxic protein aggregation, molecular chaperones stabilize denatured sarcomere proteins and promote their refolding. However, when old and misfolded proteins cannot be salvaged by chaperones, they must be recycled via degradation pathways: the calpain and ubiquitin-proteasome systems, which operate under basal conditions, and the stress-responsive autophagy-lysosome pathway. Mutations to and deficiency of the molecular chaperones and associated factors charged with sarcomere maintenance commonly lead to sarcomere structural disarray and the progression of heart disease, highlighting the necessity of effective sarcomere PQC for maintaining cardiac function. This review focuses on the dynamic regulation of assembly and turnover at the sarcomere with an emphasis on the chaperones involved in these processes and describes the alterations to chaperones - through mutations and deficient expression - implicated in disease progression to heart failure.
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Martin A, Wolcott NS, O'Connell LA. Bringing immersive science to undergraduate laboratory courses using CRISPR gene knockouts in frogs and butterflies. ACTA ACUST UNITED AC 2020; 223:223/Suppl_1/jeb208793. [PMID: 32034043 DOI: 10.1242/jeb.208793] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The use of CRISPR/Cas9 for gene editing offers new opportunities for biology students to perform genuine research exploring the gene-to-phenotype relationship. It is important to introduce the next generation of scientists, health practitioners and other members of society to the technical and ethical aspects of gene editing. Here, we share our experience leading hands-on undergraduate laboratory classes, where students formulate hypotheses regarding the roles of candidate genes involved in development, perform loss-of-function experiments using programmable nucleases and analyze the phenotypic effects of mosaic mutant animals. This is enabled by the use of the amphibian Xenopus laevis and the butterfly Vanessa cardui, two organisms that reliably yield hundreds of large and freshly fertilized eggs in a scalable manner. Frogs and butterflies also present opportunities to teach key biological concepts about gene regulation and development. To complement these practical aspects, we describe learning activities aimed at equipping students with a broad understanding of genome editing techniques, their application in fundamental and translational research, and the bioethical challenges they raise. Overall, our work supports the introduction of CRISPR technology into undergraduate classrooms and, when coupled with classroom undergraduate research experiences, enables hypothesis-driven research by undergraduates.
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Affiliation(s)
- Arnaud Martin
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Nora S Wolcott
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
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Dafsari HS, Kocaturk NM, Daimagüler HS, Brunn A, Dötsch J, Weis J, Deckert M, Cirak S. Bi-allelic mutations in uncoordinated mutant number-45 myosin chaperone B are a cause for congenital myopathy. Acta Neuropathol Commun 2019; 7:211. [PMID: 31852522 PMCID: PMC6921565 DOI: 10.1186/s40478-019-0869-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 12/10/2019] [Indexed: 11/29/2022] Open
Abstract
Congenital myopathies (CM) form a genetically heterogeneous group of disorders characterized by perinatal muscle weakness. Here, we report an 11-year old male offspring of consanguineous parents of Lebanese origin. He presented with proximal weakness including Gower’s sign, and skeletal muscle biopsy revealed myopathic changes with core-like structures. Whole exome sequencing of this index patient lead to the discovery of a novel genetically defined CM subtype based on bi-allelic mutations in the uncoordinated mutant number-45 myosin chaperone B (UNC45B) NM_173167:c.2261G > A, p.Arg754Gln. The mutation is conserved in evolution and co-segregates within the pedigree with the phenotype, and located in the myosin binding armadillo repeat domain 3 (ARM3), and has a CADD Score of 35. On a multimeric level, UNC45B aggregates to a chain which serves as an assembly line and functions as a “template” defining the geometry, regularity, and periodicity of myosin arranged into muscle thick filaments. Our discovery is in line with the previously described myopathological phenotypes in C. elegans and in vertebrate mutants and knockdown–models. In conclusion, we here report for the first time a patient with an UNC45B mutation causing a novel genetically defined congenital myopathy disease entity.
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10
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Prill K, Carlisle C, Stannard M, Windsor Reid PJ, Pilgrim DB. Myomesin is part of an integrity pathway that responds to sarcomere damage and disease. PLoS One 2019; 14:e0224206. [PMID: 31644553 PMCID: PMC6808450 DOI: 10.1371/journal.pone.0224206] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 10/08/2019] [Indexed: 12/17/2022] Open
Abstract
The structure and function of the sarcomere of striated muscle is well studied but the steps of sarcomere assembly and maintenance remain under-characterized. With the aid of chaperones and factors of the protein quality control system, muscle proteins can be folded and assembled into the contractile apparatus of the sarcomere. When sarcomere assembly is incomplete or the sarcomere becomes damaged, suites of chaperones and maintenance factors respond to repair the sarcomere. Here we show evidence of the importance of the M-line proteins, specifically myomesin, in the monitoring of sarcomere assembly and integrity in previously characterized zebrafish muscle mutants. We show that myomesin is one of the last proteins to be incorporated into the assembling sarcomere, and that in skeletal muscle, its incorporation requires connections with both titin and myosin. In diseased zebrafish sarcomeres, myomesin1a shows an early increase of gene expression, hours before chaperones respond to damaged muscle. We found that myomesin expression is also more specific to sarcomere damage than muscle creatine kinase, and our results and others support the use of myomesin assays as an early, specific, method of detecting muscle damage.
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Affiliation(s)
- Kendal Prill
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Casey Carlisle
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Megan Stannard
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | | | - David B. Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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11
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Hellerschmied D, Lehner A, Franicevic N, Arnese R, Johnson C, Vogel A, Meinhart A, Kurzbauer R, Deszcz L, Gazda L, Geeves M, Clausen T. Molecular features of the UNC-45 chaperone critical for binding and folding muscle myosin. Nat Commun 2019; 10:4781. [PMID: 31636255 PMCID: PMC6803673 DOI: 10.1038/s41467-019-12667-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 09/21/2019] [Indexed: 12/16/2022] Open
Abstract
Myosin is a motor protein that is essential for a variety of processes ranging from intracellular transport to muscle contraction. Folding and assembly of myosin relies on a specific chaperone, UNC-45. To address its substrate-targeting mechanism, we reconstitute the interplay between Caenorhabditis elegans UNC-45 and muscle myosin MHC-B in insect cells. In addition to providing a cellular chaperone assay, the established system enabled us to produce large amounts of functional muscle myosin, as evidenced by a biochemical and structural characterization, and to directly monitor substrate binding to UNC-45. Data from in vitro and cellular chaperone assays, together with crystal structures of binding-deficient UNC-45 mutants, highlight the importance of utilizing a flexible myosin-binding domain. This so-called UCS domain can adopt discrete conformations to efficiently bind and fold substrate. Moreover, our data uncover the molecular basis of temperature-sensitive UNC-45 mutations underlying one of the most prominent motility defects in C. elegans. Myosin, a motor protein essential for intracellular transport to muscle contraction, requires a chaperone UNC-45 for folding and assembly. Here authors use in vitro reconstitution and structural biology to characterize the interplay between UNC-45 and muscle myosin MHC-B.
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Affiliation(s)
- Doris Hellerschmied
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria. .,Faculty of Biology, Center of Medical Biotechnology, University Duisburg-Essen, Essen, Germany.
| | | | - Nina Franicevic
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Renato Arnese
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Chloe Johnson
- School of Biosciences, University of Kent, Canterbury, UK
| | - Antonia Vogel
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Anton Meinhart
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Robert Kurzbauer
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Luiza Deszcz
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Linn Gazda
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Michael Geeves
- School of Biosciences, University of Kent, Canterbury, UK
| | - Tim Clausen
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria. .,Medical University Vienna, Vienna, Austria.
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12
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Bujalowski PJ, Nicholls P, Garza E, Oberhauser AF. The central domain of UNC-45 chaperone inhibits the myosin power stroke. FEBS Open Bio 2018; 8:41-48. [PMID: 29321955 PMCID: PMC5757175 DOI: 10.1002/2211-5463.12346] [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: 09/18/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 11/07/2022] Open
Abstract
The multidomain UNC-45B chaperone is crucial for the proper folding and function of sarcomeric myosin. We recently found that UNC-45B inhibits the translocation of actin by myosin. The main functions of the UCS and TPR domains are known but the role of the central domain remains obscure. Here, we show-using in vitro myosin motility and ATPase assays-that the central domain alone acts as an inhibitor of the myosin power stroke through a mechanism that allows ATP turnover. Hence, UNC-45B is a unique chaperone in which the TPR domain recruits Hsp90; the UCS domain possesses chaperone-like activities; and the central domain interacts with myosin and inhibits the actin translocation function of myosin. We hypothesize that the inhibitory function plays a critical role during the assembly of myofibrils under stress and during the sarcomere development process.
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Affiliation(s)
- Paul J Bujalowski
- Department of Biochemistry and Molecular Biology The University of Texas Medical Branch Galveston TX USA
| | - Paul Nicholls
- Baylor College of Medicine The University of Texas Medical Branch Galveston TX USA
| | - Eleno Garza
- Department of Neuroscience and Cell Biology The University of Texas Medical Branch Galveston TX USA
| | - Andres F Oberhauser
- Department of Biochemistry and Molecular Biology The University of Texas Medical Branch Galveston TX USA.,Department of Neuroscience and Cell Biology The University of Texas Medical Branch Galveston TX USA.,Sealy Center for Structural Biology and Molecular Biophysics The University of Texas Medical Branch Galveston TX USA
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13
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Lehtimäki JI, Fenix AM, Kotila TM, Balistreri G, Paavolainen L, Varjosalo M, Burnette DT, Lappalainen P. UNC-45a promotes myosin folding and stress fiber assembly. J Cell Biol 2017; 216:4053-4072. [PMID: 29055011 PMCID: PMC5716280 DOI: 10.1083/jcb.201703107] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/28/2017] [Accepted: 09/19/2017] [Indexed: 12/15/2022] Open
Abstract
Contractile actomyosin bundles, stress fibers, are crucial for adhesion, morphogenesis, and mechanosensing in nonmuscle cells. However, the mechanisms by which nonmuscle myosin II (NM-II) is recruited to those structures and assembled into functional bipolar filaments have remained elusive. We report that UNC-45a is a dynamic component of actin stress fibers and functions as a myosin chaperone in vivo. UNC-45a knockout cells display severe defects in stress fiber assembly and consequent abnormalities in cell morphogenesis, polarity, and migration. Experiments combining structured-illumination microscopy, gradient centrifugation, and proteasome inhibition approaches revealed that a large fraction of NM-II and myosin-1c molecules fail to fold in the absence of UNC-45a. The remaining properly folded NM-II molecules display defects in forming functional bipolar filaments. The C-terminal UNC-45/Cro1/She4p domain of UNC-45a is critical for NM-II folding, whereas the N-terminal tetratricopeptide repeat domain contributes to the assembly of functional stress fibers. Thus, UNC-45a promotes generation of contractile actomyosin bundles through synchronized NM-II folding and filament-assembly activities.
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Affiliation(s)
| | - Aidan M Fenix
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Tommi M Kotila
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Giuseppe Balistreri
- Department of Biosciences, Division of General Microbiology, University of Helsinki, Helsinki, Finland
| | - Lassi Paavolainen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Markku Varjosalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Dylan T Burnette
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Pekka Lappalainen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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14
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Abstract
In this review we discuss the history and the current state of ideas related to the mechanism of size regulation of the thick (myosin) and thin (actin) filaments in vertebrate striated muscles. Various hypotheses have been considered during of more than half century of research, recently mostly involving titin and nebulin acting as templates or 'molecular rulers', terminating exact assembly. These two giant, single-polypeptide, filamentous proteins are bound in situ along the thick and thin filaments, respectively, with an almost perfect match in the respective lengths and structural periodicities. However, evidence still questions the possibility that the proteins function as templates, or scaffolds, on which the thin and thick filaments could be assembled. In addition, the progress in muscle research during the last decades highlighted a number of other factors that could potentially be involved in the mechanism of length regulation: molecular chaperones that may guide folding and assembly of actin and myosin; capping proteins that can influence the rates of assembly-disassembly of the myofilaments; Ca2+ transients that can activate or deactivate protein interactions, etc. The entire mechanism of sarcomere assembly appears complex and highly dynamic. This mechanism is also capable of producing filaments of about the correct size without titin and nebulin. What then is the role of these proteins? Evidence points to titin and nebulin stabilizing structures of the respective filaments. This stabilizing effect, based on linear proteins of a fixed size, implies that titin and nebulin are indeed molecular rulers of the filaments. Although the proteins may not function as templates in the assembly of the filaments, they measure and stabilize exactly the same size of the functionally important for the muscles segments in each of the respective filaments.
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15
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Etard C, Armant O, Roostalu U, Gourain V, Ferg M, Strähle U. Loss of function of myosin chaperones triggers Hsf1-mediated transcriptional response in skeletal muscle cells. Genome Biol 2015; 16:267. [PMID: 26631063 PMCID: PMC4668643 DOI: 10.1186/s13059-015-0825-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/05/2015] [Indexed: 01/03/2023] Open
Abstract
Background Mutations in myosin chaperones Unc45b and Hsp90aa1.1 as well as in the Unc45b-binding protein Smyd1b impair formation of myofibrils in skeletal muscle and lead to the accumulation of misfolded myosin. The concomitant transcriptional response involves up-regulation of the three genes encoding these proteins, as well as genes involved in muscle development. The transcriptional up-regulation of unc45b, hsp90aa1.1 and smyd1b is specific to zebrafish mutants with myosin folding defects, and is not triggered in other zebrafish myopathy models. Results By dissecting the promoter of unc45b, we identify a Heat shock factor 1 (Hsf1) binding element as a mediator of unc45b up-regulation in myofibers lacking myosin folding proteins. Loss-of-function of Hsf1 abolishes unc45b up-regulation in mutants with defects in myosin folding. Conclusions Taken together, our data show that skeletal muscle cells respond to defective myosin chaperones with a complex gene program and suggest that this response is mediated by Hsf1 activation. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0825-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Christelle Etard
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus Nord, PO box, Karlsruhe, Germany
| | - Olivier Armant
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus Nord, PO box, Karlsruhe, Germany
| | - Urmas Roostalu
- Present address: Institute of Inflammation and Repair, Michael Smith Bldg, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Victor Gourain
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus Nord, PO box, Karlsruhe, Germany
| | - Marco Ferg
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus Nord, PO box, Karlsruhe, Germany
| | - Uwe Strähle
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus Nord, PO box, Karlsruhe, Germany.
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16
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Prill K, Windsor Reid P, Wohlgemuth SL, Pilgrim DB. Still Heart Encodes a Structural HMT, SMYD1b, with Chaperone-Like Function during Fast Muscle Sarcomere Assembly. PLoS One 2015; 10:e0142528. [PMID: 26544721 PMCID: PMC4636364 DOI: 10.1371/journal.pone.0142528] [Citation(s) in RCA: 11] [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: 01/09/2015] [Accepted: 10/22/2015] [Indexed: 01/16/2023] Open
Abstract
The vertebrate sarcomere is a complex and highly organized contractile structure whose assembly and function requires the coordination of hundreds of proteins. Proteins require proper folding and incorporation into the sarcomere by assembly factors, and they must also be maintained and replaced due to the constant physical stress of muscle contraction. Zebrafish mutants affecting muscle assembly and maintenance have proven to be an ideal tool for identification and analysis of factors necessary for these processes. The still heart mutant was identified due to motility defects and a nonfunctional heart. The cognate gene for the mutant was shown to be smyd1b and the still heart mutation results in an early nonsense codon. SMYD1 mutants show a lack of heart looping and chamber definition due to a lack of expression of heart morphogenesis factors gata4, gata5 and hand2. On a cellular level, fast muscle fibers in homozygous mutants do not form mature sarcomeres due to the lack of fast muscle myosin incorporation by SMYD1b when sarcomeres are first being assembled (19hpf), supporting SMYD1b as an assembly protein during sarcomere formation.
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Affiliation(s)
- Kendal Prill
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Pamela Windsor Reid
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Serene L. Wohlgemuth
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - David B. Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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17
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Geach TJ, Hirst EMA, Zimmerman LB. Contractile activity is required for Z-disc sarcomere maturation in vivo. Genesis 2015; 53:299-307. [PMID: 25845369 PMCID: PMC4676352 DOI: 10.1002/dvg.22851] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 01/16/2023]
Abstract
Sarcomere structure underpins structural integrity, signaling, and force transmission in the muscle. In embryos of the frog Xenopus tropicalis, muscle contraction begins even while sarcomerogenesis is ongoing. To determine whether contractile activity plays a role in sarcomere formation in vivo, chemical tools were used to block acto-myosin contraction in embryos of the frog X. tropicalis, and Z-disc assembly was characterized in the paralyzed dicky ticker mutant. Confocal and ultrastructure analysis of paralyzed embryos showed delayed Z-disc formation and defects in thick filament organization. These results suggest a previously undescribed role for contractility in sarcomere maturation in vivo. genesis 53:299–307, 2015. © 2015 The Authors. Genesis Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Timothy J Geach
- Division of Developmental Biology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Elizabeth M A Hirst
- Division of Developmental Biology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Lyle B Zimmerman
- Division of Developmental Biology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
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18
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Abstract
The UCS (UNC-45/CRO1/She4p) family of proteins has emerged as chaperones that are specific for the folding, assembly and function of myosin. These proteins participate in various important myosin-dependent cellular processes that include myofibril organization and muscle functions, cell differentiation, cardiac and skeletal muscle development, cytokinesis and endocytosis. Mutations in the genes that code for UCS proteins cause serious defects in these actomyosin-based processes. Homologs of UCS proteins can be broadly divided into (1) animal UCS proteins, generally known as UNC-45 proteins, which contain an N-terminal tetratricopeptide repeat (TPR) domain in addition to the canonical UCS domain, and (2) fungal UCS proteins, which lack the TPR domain. Structurally, except for TPR domain, both sub-classes of UCS proteins comprise of several irregular armadillo (ARM) repeats that are divided into two-domain architecture: a combined central-neck domain and a C-terminal UCS domain. Structural analyses suggest that UNC-45 proteins form elongated oligomers that serve as scaffolds to recruit Hsp90 and/or Hsp70 to form a multi-protein chaperoning complex that assists myosin heads to fold and simultaneously organize them into myofibrils. Similarly, fungal UCS proteins may dimerize to promote folding of non-muscle myosins as well as determine their step size along actin filaments. These findings confirm UCS proteins as a new class of myosin-specific chaperones and co-chaperones for Hsp90. This chapter reviews the implications of the outcome of studies on these proteins in cellular processes such as muscle formation, and disease states such as myopathies and cancer.
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Affiliation(s)
- Weiming Ni
- Department of Genetics, Howard Hughes Medical Institute, Yale School of Medicine, 06520, New Haven, CT, USA,
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19
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Myhre JL, Hills JA, Jean F, Pilgrim DB. Unc45b is essential for early myofibrillogenesis and costamere formation in zebrafish. Dev Biol 2014; 390:26-40. [DOI: 10.1016/j.ydbio.2014.02.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 02/25/2014] [Indexed: 01/16/2023]
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20
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Schmitt SM, Gull M, Brändli AW. Engineering Xenopus embryos for phenotypic drug discovery screening. Adv Drug Deliv Rev 2014; 69-70:225-46. [PMID: 24576445 DOI: 10.1016/j.addr.2014.02.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 02/08/2023]
Abstract
Many rare human inherited diseases remain untreatable despite the fact that the disease causing genes are known and adequate mouse disease models have been developed. In vivo phenotypic drug screening relies on isolating drug candidates by their ability to produce a desired therapeutic phenotype in whole organisms. Embryos of zebrafish and Xenopus frogs are abundant, small and free-living. They can be easily arrayed in multi-well dishes and treated with small organic molecules. With the development of novel genome modification tools, such a zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and CRISPR/Cas, it is now possible to efficiently engineer non-mammalian models of inherited human diseases. Here, we will review the rapid progress made in adapting these novel genome editing tools to Xenopus. The advantages of Xenopus embryos as in vivo models to study human inherited diseases will be presented and their utility for drug discovery screening will be discussed. Being a tetrapod, Xenopus complements zebrafish as an indispensable non-mammalian animal model for the study of human disease pathologies and the discovery of novel therapeutics for inherited diseases.
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21
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The myosin chaperone UNC45B is involved in lens development and autosomal dominant juvenile cataract. Eur J Hum Genet 2014; 22:1290-7. [PMID: 24549050 DOI: 10.1038/ejhg.2014.21] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 01/17/2014] [Accepted: 01/22/2014] [Indexed: 01/17/2023] Open
Abstract
Genome-wide linkage analysis, followed by targeted deep sequencing, in a Danish multigeneration family with juvenile cataract revealed a region of chromosome 17 co-segregating with the disease trait. Affected individuals were heterozygous for two potentially protein-disrupting alleles in this region, in ACACA and UNC45B. As alterations of the UNC45B protein have been shown to affect eye development in model organisms, effort was focused on the heterozygous UNC45B missense mutation. UNC45B encodes a myosin-specific chaperone that, together with the general heat shock protein HSP90, is involved in myosin assembly. The mutation changes p.Arg805 to Trp in the UCS domain, an amino acid that is highly conserved from yeast to human. UNC45B is strongly expressed in the heart and skeletal muscle tissue, but here we show expression in human embryo eye and zebrafish lens. The zebrafish mutant steif, carrying an unc45b nonsense mutation, has smaller eyes than wild-type embryos and shows accumulation of nuclei in the lens. Injection of RNA encoding the human wild-type UNC45B protein into the steif homozygous embryo reduced the nuclei accumulation and injection of human mutant UNC45B cDNA in wild-type embryos resulted in development of a phenotype similar to the steif mutant. The p.Arg805Trp alteration in the mammalian UNC45B gene suggests that developmental cataract may be caused by a defect in non-muscle myosin assembly during maturation of the lens fiber cells.
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22
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Lee CF, Melkani GC, Bernstein SI. The UNC-45 myosin chaperone: from worms to flies to vertebrates. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 313:103-44. [PMID: 25376491 DOI: 10.1016/b978-0-12-800177-6.00004-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
UNC-45 (uncoordinated mutant number 45) is a UCS (UNC-45, CRO1, She4p) domain protein that is critical for myosin stability and function. It likely aides in folding myosin during cellular differentiation and maintenance, and protects myosin from denaturation during stress. Invertebrates have a single unc-45 gene that is expressed in both muscle and nonmuscle tissues. Vertebrates possess one gene expressed in striated muscle (unc-45b) and another that is more generally expressed (unc-45a). Structurally, UNC-45 is composed of a series of α-helices connected by loops. It has an N-terminal tetratricopeptide repeat domain that binds to Hsp90 and a central domain composed of armadillo repeats. Its C-terminal UCS domain, which is also comprised of helical armadillo repeats, interacts with myosin. In this chapter, we present biochemical, structural, and genetic analyses of UNC-45 in Caenorhabditis elegans, Drosophila melanogaster, and various vertebrates. Further, we provide insights into UNC-45 functions, its potential mechanism of action, and its roles in human disease.
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Affiliation(s)
- Chi F Lee
- Department of Biology, San Diego State University, San Diego, CA, USA
| | - Girish C Melkani
- Department of Biology, San Diego State University, San Diego, CA, USA
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23
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Hellerschmied D, Clausen T. Myosin chaperones. Curr Opin Struct Biol 2013; 25:9-15. [PMID: 24440450 PMCID: PMC4045384 DOI: 10.1016/j.sbi.2013.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 11/08/2013] [Accepted: 11/08/2013] [Indexed: 12/31/2022]
Abstract
The folding and assembly of myosin motor proteins is essential for most movement processes at the cellular, but also at the organism level. Importantly, myosins, which represent a very diverse family of proteins, require the activity of general and specialized folding factors to develop their full motor function. The activities of the myosin-specific UCS (UNC-45/Cro1/She4) chaperones range from assisting acto-myosin dependent transport processes to scaffolding multi-subunit chaperone complexes, which are required to assemble myofilaments. Recent structure-function studies revealed the structural organization of TPR (tetratricopeptide repeat)-containing and TPR-less UCS chaperones. The observed structural differences seem to reflect the specialized and remarkably versatile working mechanisms of myosin-directed chaperones, as will be discussed in this review.
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Affiliation(s)
- Doris Hellerschmied
- Research Institute of Molecular Pathology, Dr. Bohrgasse 7, A-1030 Vienna, Austria
| | - Tim Clausen
- Research Institute of Molecular Pathology, Dr. Bohrgasse 7, A-1030 Vienna, Austria.
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24
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Nworu CU, Krieg PA, Gregorio CC. Preparation of developing Xenopus muscle for sarcomeric protein localization by high-resolution imaging. Methods 2013; 66:370-9. [PMID: 23806641 DOI: 10.1016/j.ymeth.2013.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 11/16/2022] Open
Abstract
Mutations in several sarcomeric proteins have been linked to various human myopathies. Therefore, having an in vivo developmental model available that develops quickly and efficiently is key for investigators to elucidate the critical steps, components and signaling pathways involved in building a myofibril; this is the pivotal foundation for deciphering disease mechanisms as well as the development of myopathy-related therapeutics. Although striated muscle cell culture studies have been extremely informative in providing clues to both the distribution and functions of sarcomeric proteins, myocytes in vivo develop in an irreproducible 3D environment. Xenopus laevis (frog) embryos are cost effective, compliant to protein level manipulations and develop relatively quickly (⩽ a week) in a petri dish, thus providing a powerful system for de novo myofibrillogenesis studies. Although fluorophore-conjugated phalloidin labeling is the gold standard approach for investigating actin-thin filament architecture, it is well documented that phalloidin-labeling can be challenging and inconsistent within Xenopus embryos. Therefore we highlight several techniques that can be utilized to preserve both antibody and fluorophore-conjugated phalloidin labeling within Xenopus embryos for high-resolution fluorescence microscopy.
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Affiliation(s)
- Chinedu U Nworu
- Department of Cellular and Molecular Medicine and The Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Paul A Krieg
- Department of Cellular and Molecular Medicine and The Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine and The Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA.
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The myosin chaperone UNC-45 is organized in tandem modules to support myofilament formation in C. elegans. Cell 2013; 152:183-95. [PMID: 23332754 PMCID: PMC3549490 DOI: 10.1016/j.cell.2012.12.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 11/01/2012] [Accepted: 12/11/2012] [Indexed: 01/16/2023]
Abstract
The UCS (UNC-45/CRO1/She4) chaperones play an evolutionarily conserved role in promoting myosin-dependent processes, including cytokinesis, endocytosis, RNA transport, and muscle development. To investigate the protein machinery orchestrating myosin folding and assembly, we performed a comprehensive analysis of Caenorhabditis elegans UNC-45. Our structural and biochemical data demonstrate that UNC-45 forms linear protein chains that offer multiple binding sites for cooperating chaperones and client proteins. Accordingly, Hsp70 and Hsp90, which bind to the TPR domain of UNC-45, could act in concert and with defined periodicity on captured myosin molecules. In vivo analyses reveal the elongated canyon of the UCS domain as a myosin-binding site and show that multimeric UNC-45 chains support organization of sarcomeric repeats. In fact, expression of transgenes blocking UNC-45 chain formation induces dominant-negative defects in the sarcomere structure and function of wild-type worms. Together, these findings uncover a filament assembly factor that directly couples myosin folding with myofilament formation.
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del Viso F, Bhattacharya D, Kong Y, Gilchrist MJ, Khokha MK. Exon capture and bulk segregant analysis: rapid discovery of causative mutations using high-throughput sequencing. BMC Genomics 2012; 13:649. [PMID: 23171430 PMCID: PMC3526394 DOI: 10.1186/1471-2164-13-649] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 11/15/2012] [Indexed: 11/21/2022] Open
Abstract
Background Exome sequencing has transformed human genetic analysis and may do the same for other vertebrate model systems. However, a major challenge is sifting through the large number of sequence variants to identify the causative mutation for a given phenotype. In models like Xenopus tropicalis, an incomplete and occasionally incorrect genome assembly compounds this problem. To facilitate cloning of X. tropicalis mutants identified in forward genetic screens, we sought to combine bulk segregant analysis and exome sequencing into a single step. Results Here we report the first use of exon capture sequencing to identify mutations in a non-mammalian, vertebrate model. We demonstrate that bulk segregant analysis coupled with exon capture sequencing is not only able to identify causative mutations but can also generate linkage information, facilitate the assembly of scaffolds, identify misassembles, and discover thousands of SNPs for fine mapping. Conclusion Exon capture sequencing and bulk segregant analysis is a rapid, inexpensive method to clone mutants identified in forward genetic screens. With sufficient meioses, this method can be generalized to any model system with a genome assembly, polished or unpolished, and in the latter case, it also provides many critical genomic resources.
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Affiliation(s)
- Florencia del Viso
- Department of Pediatrics and Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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27
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Comyn SA, Pilgrim D. Lack of developmental redundancy between Unc45 proteins in zebrafish muscle development. PLoS One 2012; 7:e48861. [PMID: 23144999 PMCID: PMC3492250 DOI: 10.1371/journal.pone.0048861] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 10/03/2012] [Indexed: 01/09/2023] Open
Abstract
Since the majority of protein-coding genes in vertebrates have intra-genomic homologues, it has been difficult to eliminate the potential of functional redundancy from analyses of mutant phenotypes, whether produced by genetic lesion or transient knockdown. Further complicating these analyses, not all gene products have activities that can be assayed in vitro, where the efficiency of the various family members can be compared against constant substrates. Two vertebrate UNC-45 homologues, unc45a and unc45b, affect distinct stages of muscle differentiation when knocked down in cell culture and are functionally redundant in vitro. UNC-45 proteins are members of the UCS (UNC-45/CRO1/She4p) protein family that has been shown to regulate myosin-dependent functions from fungi to vertebrates through direct interaction with the myosin motor domain. To test whether the same functional relationship exists between these unc45 paralogs in vivo, we examined the developmental phenotypes of doubly homozygous unc45b−/−; unc45a−/− mutant zebrafish embryos. We focused specifically on the combined effects on morphology and gene expression resulting from the zygotic lack of both paralogs. We found that unc45b−/− and unc45b−/−; unc45a−/− embryos were phenotypically indistinguishable with both mutants displaying identical cardiac, skeletal muscle, and jaw defects. We also found no evidence to support a role for zygotic Unc45a function in myoblast differentiation. In contrast to previous in vitro work, this rules out a model of functional redundancy between Unc45a and Unc45b in vivo. Instead, our phylogenetic and phenotypic analyses provide evidence for the role of functional divergence in the evolution of the UCS protein family.
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Affiliation(s)
| | - David Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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28
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Khokha MK. Xenopuswhite papers and resources: Folding functional genomics and genetics into the frog. Genesis 2012; 50:133-42. [DOI: 10.1002/dvg.22015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/13/2012] [Accepted: 01/15/2012] [Indexed: 02/04/2023]
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Abu-Daya A, Khokha MK, Zimmerman LB. The hitchhiker's guide to Xenopus genetics. Genesis 2012; 50:164-75. [PMID: 22344745 DOI: 10.1002/dvg.22007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 12/19/2011] [Accepted: 12/23/2011] [Indexed: 01/12/2023]
Abstract
A decade after the human genome sequence, most vertebrate gene functions remain poorly understood, limiting benefits to human health from rapidly advancing genomic technologies. Systematic in vivo functional analysis is ideally suited to the experimentally accessible Xenopus embryo, which combines embryological accessibility with a broad range of transgenic, biochemical, and gain-of-function assays. The diploid X. tropicalis adds loss-of-function genetics and enhanced genomics to this repertoire. In the last decade, diverse phenotypes have been recovered from genetic screens, mutations have been cloned, and reverse genetics in the form of TILLING and targeted gene editing have been established. Simple haploid genetics and gynogenesis and the very large number of embryos produced streamline screening and mapping. Improved genomic resources and the revolution in high-throughput sequencing are transforming mutation cloning and reverse genetic approaches. The combination of loss-of-function mutant backgrounds with the diverse array of conventional Xenopus assays offers a uniquely flexible platform for analysis of gene function in vertebrate development.
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Affiliation(s)
- Anita Abu-Daya
- Division of Developmental Biology, MRC-National Institute for Medical Research, Mill Hill, London, United Kingdom
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30
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At the Start of the Sarcomere: A Previously Unrecognized Role for Myosin Chaperones and Associated Proteins during Early Myofibrillogenesis. Biochem Res Int 2012; 2012:712315. [PMID: 22400118 PMCID: PMC3287041 DOI: 10.1155/2012/712315] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 10/10/2011] [Indexed: 01/03/2023] Open
Abstract
The development of striated muscle in vertebrates requires the assembly of contractile myofibrils, consisting of highly ordered bundles of protein filaments. Myofibril formation occurs by the stepwise addition of complex proteins, a process that is mediated by a variety of molecular chaperones and quality control factors. Most notably, myosin of the thick filament requires specialized chaperone activity during late myofibrillogenesis, including that of Hsp90 and its cofactor, Unc45b. Unc45b has been proposed to act exclusively as an adaptor molecule, stabilizing interactions between Hsp90 and myosin; however, recent discoveries in zebrafish and C. elegans suggest the possibility of an earlier role for Unc45b during myofibrillogenesis. This role may involve functional control of nonmuscle myosins during the earliest stages of myogenesis, when premyofibril scaffolds are first formed from dynamic cytoskeletal actin. This paper will outline several lines of evidence that converge to build a model for Unc45b activity during early myofibrillogenesis.
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31
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Abstract
The pipid frog Xenopus tropicalis has emerged as a powerful new model system for combining genetic and genomic analysis of tetrapod development with robust embryological, molecular, and biochemical assays. Its early development closely resembles that of its well-understood relative X. laevis, from which techniques and reagents can be readily transferred. In contrast to the tetraploid X. laevis, X. tropicalis has a compact diploid genome with strong synteny to those of amniotes. Recently, advances in high-throughput sequencing together with solution-hybridization whole-exome enrichment technology offer powerful strategies for cloning novel mutations as well as reverse genetic identification of sequence lesions in specific genes of interest. Further advantages include the wide range of functional and molecular assays available, the large number of embryos/meioses produced, and the ease of haploid genetics and gynogenesis. The addition of these genetic tools to X. tropicalis provides a uniquely flexible platform for analysis of gene function in vertebrate development.
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Affiliation(s)
- Timothy J. Geach
- National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA United Kingdom
| | | | - Lyle B. Zimmerman
- National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA United Kingdom
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32
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Abstract
Xenopus tropicalis combine the advantages of X. laevis, for example using explants and targeted gain of function, with the ability to take classical genetics approaches to answering cell and developmental biology questions making it arguably the most versatile of the model organisms. Against this background, husbandry of X. tropicalis is less well developed than for its larger, more robust relative. Here we describe the methods used to keep and breed these frogs successfully.
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Affiliation(s)
- Alan Jafkins
- European Xenopus Resource Centre, School of Biological Sciences, University of Portsmouth, Portsmouth, England, UK
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33
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Abstract
Xenopus tropicalis was introduced as a model system for genetic, and then genomic research, in the early 1990s, complementing work on the widely used model organism Xenopus laevis. Its shorter generation time and diploid genome has facilitated a number of experimental approaches. It has permitted multigenerational experiments (e.g., preparation of transgenic lines and generation of mutant lines) that have added powerful approaches for research by the Xenopus community. As a diploid animal, its simpler genome was sequenced before X. laevis, and has provided a highly valuable resource indispensable for all Xenopus researchers. As more sophisticated transgenic technologies for manipulating gene expression are developed, and mutations, particularly null mutations, are identified in widely studied genes involved in critical cellular and developmental processes, researchers will increasingly turn to X. tropicalis for definitive analysis of complex genetic pathways. This chapter describes the historical and conceptual development of X. tropicalis as a genetic and genomic model system for higher vertebrate development.
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Affiliation(s)
- Robert M Grainger
- Department of Biology, University of Virginia, Charlottesville, VA, USA.
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34
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Dwyer J, Iskratsch T, Ehler E. Actin in striated muscle: recent insights into assembly and maintenance. Biophys Rev 2011; 4:17-25. [PMID: 28510000 DOI: 10.1007/s12551-011-0062-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 11/17/2011] [Indexed: 01/28/2023] Open
Abstract
Striated muscle cells are characterised by a para-crystalline arrangement of their contractile proteins actin and myosin in sarcomeres, the basic unit of the myofibrils. A multitude of proteins is required to build and maintain the structure of this regular arrangement as well as to ensure regulation of contraction and to respond to alterations in demand. This review focuses on the actin filaments (also called thin filaments) of the sarcomere and will discuss how they are assembled during myofibrillogenesis and in hypertrophy and how their integrity is maintained in the working myocardium.
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Affiliation(s)
- Joseph Dwyer
- The Randall Division of Cell and Molecular Biophysics and The Cardiovascular Division, King's College London, British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, London, SE1 1UL, UK
| | - Thomas Iskratsch
- The Randall Division of Cell and Molecular Biophysics and The Cardiovascular Division, King's College London, British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.,Biological Sciences, Columbia University, 713 Fairchild Center, New York, NY, 10027, USA
| | - Elisabeth Ehler
- The Randall Division of Cell and Molecular Biophysics and The Cardiovascular Division, King's College London, British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.
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35
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Harland RM, Grainger RM. Xenopus research: metamorphosed by genetics and genomics. Trends Genet 2011; 27:507-15. [PMID: 21963197 PMCID: PMC3601910 DOI: 10.1016/j.tig.2011.08.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 08/25/2011] [Accepted: 08/25/2011] [Indexed: 01/18/2023]
Abstract
Research using Xenopus takes advantage of large, abundant eggs and readily manipulated embryos in addition to conserved cellular, developmental and genomic organization with mammals. Research on Xenopus has defined key principles of gene regulation and signal transduction, embryonic induction, morphogenesis and patterning as well as cell cycle regulation. Genomic and genetic advances in this system, including the development of Xenopus tropicalis as a genetically tractable complement to the widely used Xenopus laevis, capitalize on the classical strengths and wealth of achievements. These attributes provide the tools to tackle the complex biological problems of the new century, including cellular reprogramming, organogenesis, regeneration, gene regulatory networks and protein interactions controlling growth and development, all of which provide insights into a multitude of human diseases and their potential treatments.
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Affiliation(s)
- Richard M Harland
- Department of Molecular and Cell Biology, Center for Integrative Genomics, University of California Berkeley, CA 94720, USA
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36
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Melkani GC, Bodmer R, Ocorr K, Bernstein SI. The UNC-45 chaperone is critical for establishing myosin-based myofibrillar organization and cardiac contractility in the Drosophila heart model. PLoS One 2011; 6:e22579. [PMID: 21799905 PMCID: PMC3143160 DOI: 10.1371/journal.pone.0022579] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 06/24/2011] [Indexed: 11/25/2022] Open
Abstract
UNC-45 is a UCS (UNC-45/CRO1/She4P) class chaperone necessary for myosin folding and/or accumulation, but its requirement for maintaining cardiac contractility has not been explored. Given the prevalence of myosin mutations in eliciting cardiomyopathy, chaperones like UNC-45 are likely to be equally critical in provoking or modulating myosin-associated cardiomyopathy. Here, we used the Drosophila heart model to examine its role in cardiac physiology, in conjunction with RNAi-mediated gene silencing specifically in the heart in vivo. Analysis of cardiac physiology was carried out using high-speed video recording in conjunction with movement analysis algorithms. unc-45 knockdown resulted in severely compromised cardiac function in adults as evidenced by prolonged diastolic and systolic intervals, and increased incidence of arrhythmias and extreme dilation; the latter was accompanied by a significant reduction in muscle contractility. Structural analysis showed reduced myofibrils, myofibrillar disarray, and greatly decreased cardiac myosin accumulation. Cardiac unc-45 silencing also dramatically reduced life-span. In contrast, third instar larval and young pupal hearts showed mild cardiac abnormalities, as severe cardiac defects only developed during metamorphosis. Furthermore, cardiac unc-45 silencing in the adult heart (after metamorphosis) led to less severe phenotypes. This suggests that UNC-45 is mostly required for myosin accumulation/folding during remodeling of the forming adult heart. The cardiac defects, myosin deficit and decreased life-span in flies upon heart-specific unc-45 knockdown were significantly rescued by UNC-45 over-expression. Our results are the first to demonstrate a cardiac-specific requirement of a chaperone in Drosophila, suggestive of a critical role of UNC-45 in cardiomyopathies, including those associated with unfolded proteins in the failing human heart. The dilated cardiomyopathy phenotype associated with UNC-45 deficiency is mimicked by myosin knockdown suggesting that UNC-45 plays a crucial role in stabilizing myosin and possibly preventing human cardiomyopathies associated with functional deficiencies of myosin.
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Affiliation(s)
- Girish C. Melkani
- Department of Biology, Molecular Biology Institute and Heart Institute, San Diego State University, San Diego, California, United States of America
- Development and Aging Program, Sanford-Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Rolf Bodmer
- Development and Aging Program, Sanford-Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Karen Ocorr
- Development and Aging Program, Sanford-Burnham Institute for Medical Research, La Jolla, California, United States of America
- * E-mail: (SIB); (KO)
| | - Sanford I. Bernstein
- Department of Biology, Molecular Biology Institute and Heart Institute, San Diego State University, San Diego, California, United States of America
- * E-mail: (SIB); (KO)
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Kaltenbrun E, Tandon P, Amin NM, Waldron L, Showell C, Conlon FL. Xenopus: An emerging model for studying congenital heart disease. ACTA ACUST UNITED AC 2011; 91:495-510. [PMID: 21538812 DOI: 10.1002/bdra.20793] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 01/18/2011] [Accepted: 01/28/2011] [Indexed: 02/02/2023]
Abstract
Congenital heart defects affect nearly 1% of all newborns and are a significant cause of infant death. Clinical studies have identified a number of congenital heart syndromes associated with mutations in genes that are involved in the complex process of cardiogenesis. The African clawed frog, Xenopus, has been instrumental in studies of vertebrate heart development and provides a valuable tool to investigate the molecular mechanisms underlying human congenital heart diseases. In this review, we discuss the methodologies that make Xenopus an ideal model system to investigate heart development and disease. We also outline congenital heart conditions linked to cardiac genes that have been well studied in Xenopus and describe some emerging technologies that will further aid in the study of these complex syndromes.
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Affiliation(s)
- Erin Kaltenbrun
- University of North Carolina McAllister Heart Institute, Chapel Hill, NC 27599, USA
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38
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Lee CF, Melkani GC, Yu Q, Suggs JA, Kronert WA, Suzuki Y, Hipolito L, Price MG, Epstein HF, Bernstein SI. Drosophila UNC-45 accumulates in embryonic blastoderm and in muscles, and is essential for muscle myosin stability. J Cell Sci 2011; 124:699-705. [PMID: 21285246 DOI: 10.1242/jcs.078964] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
UNC-45 is a chaperone that facilitates folding of myosin motor domains. We have used Drosophila melanogaster to investigate the role of UNC-45 in muscle development and function. Drosophila UNC-45 (dUNC-45) is expressed at all developmental stages. It colocalizes with non-muscle myosin in embryonic blastoderm of 2-hour-old embryos. At 14 hours, it accumulates most strongly in embryonic striated muscles, similarly to muscle myosin. dUNC-45 localizes to the Z-discs of sarcomeres in third instar larval body-wall muscles. We produced a dunc-45 mutant in which zygotic expression is disrupted. This results in nearly undetectable dUNC-45 levels in maturing embryos as well as late embryonic lethality. Muscle myosin accumulation is robust in dunc-45 mutant embryos at 14 hours. However, myosin is dramatically decreased in the body-wall muscles of 22-hour-old mutant embryos. Furthermore, electron microscopy showed only a few thick filaments and irregular thick-thin filament lattice spacing. The lethality, defective protein accumulation, and ultrastructural abnormalities are rescued with a wild-type dunc-45 transgene, indicating that the mutant phenotypes arise from the dUNC-45 deficiency. Overall, our data indicate that dUNC-45 is important for myosin accumulation and muscle function. Furthermore, our results suggest that dUNC-45 acts post-translationally for proper myosin folding and maturation.
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Affiliation(s)
- Chi F Lee
- Department of Biology and the Molecular Biology Institute, San Diego State University, San Diego, CA 92182, USA
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