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Grogan A, Huang W, Brong A, Kane MA, Kontrogianni-Konstantopoulos A. Alterations in cytoskeletal and Ca 2+ cycling regulators in atria lacking the obscurin Ig58/59 module. Front Cardiovasc Med 2023; 10:1085840. [PMID: 37304957 PMCID: PMC10251194 DOI: 10.3389/fcvm.2023.1085840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/26/2023] [Indexed: 06/13/2023] Open
Abstract
Introduction Obscurin (720-870 kDa) is a giant cytoskeletal and signaling protein that possesses both structural and regulatory functions in striated muscles. Immunoglobulin domains 58/59 (Ig58/59) of obscurin bind to a diverse set of proteins that are essential for the proper structure and function of the heart, including giant titin, novex-3, and phospholamban (PLN). Importantly, the pathophysiological significance of the Ig58/59 module has been further underscored by the discovery of several mutations within Ig58/59 that are linked to various forms of myopathy in humans. We previously generated a constitutive deletion mouse model, Obscn-ΔIg58/59, that expresses obscurin lacking Ig58/59, and characterized the effects of this deletion on cardiac morphology and function through aging. Our findings demonstrated that Obscn-ΔIg58/59 male animals develop severe arrhythmia, primarily manifesting as episodes of junctional escape and spontaneous loss of regular p-waves, reminiscent of human atrial fibrillation, accompanied by significant atrial enlargement that progresses in severity with aging. Methods and Results To comprehensively characterize the molecular alterations responsible for these pathologies, we performed proteomic and phospho-proteomic analyses in aging Obscn-ΔIg58/59 atria. Our studies revealed extensive and novel alterations in the expression and phosphorylation profile of major cytoskeletal proteins, Ca2+ regulators, and Z-disk associated protein complexes in the Obscn-ΔIg58/59 atria through aging. Discussion These studies implicate obscurin, particularly the Ig58/59 module, as an essential regulator of the Z-disk associated cytoskeleton and Ca2+ cycling in the atria and provide new molecular insights into the development of atrial fibrillation and remodeling.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Weiliang Huang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Annie Brong
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
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Zacharchenko T, Dorendorf T, Locker N, Van Dijk E, Katzemich A, Diederichs K, Bullard B, Mayans O. PK1 from Drosophila obscurin is an inactive pseudokinase with scaffolding properties. Open Biol 2023; 13:220350. [PMID: 37121260 PMCID: PMC10129394 DOI: 10.1098/rsob.220350] [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: 11/25/2022] [Accepted: 03/23/2023] [Indexed: 05/02/2023] Open
Abstract
Obscurins are large filamentous proteins with crucial roles in the assembly, stability and regulation of muscle. Characteristic of these proteins is a tandem of two C-terminal kinase domains, PK1 and PK2, that are separated by a long intrinsically disordered sequence. The significance of this conserved domain arrangement is unknown. Our study of PK1 from Drosophila obscurin shows that this is a pseudokinase with features typical of the CAM-kinase family, but which carries a minimalistic regulatory tail that no longer binds calmodulin or has mechanosensory properties typical of other sarcomeric kinases. PK1 binds ATP with high affinity, but in the absence of magnesium and lacks detectable phosphotransfer activity. It also has a highly diverged active site, strictly conserved across arthropods, that might have evolved to accommodate an unconventional binder. We find that PK1 interacts with PK2, suggesting a functional relation to the latter. These findings lead us to speculate that PK1/PK2 form a pseudokinase/kinase dual system, where PK1 might act as an allosteric regulator of PK2 and where mechanosensing properties, akin to those described for regulatory tails in titin-like kinases, might now reside on the unstructured interkinase segment. We propose that the PK1-interkinase-PK2 region constitutes an integrated functional unit in obscurin proteins.
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Affiliation(s)
- Thomas Zacharchenko
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Till Dorendorf
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Evert Van Dijk
- Biosynth B.V., Zuidersluisweg 2, 8243 RC Lelystad, The Netherlands
| | | | - Kay Diederichs
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | | | - Olga Mayans
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
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Abstract
Junctophilins (JPHs) comprise a family of structural proteins that connect the plasma membrane to intracellular organelles such as the endo/sarcoplasmic reticulum. Tethering of these membrane structures results in the formation of highly organized subcellular junctions that play important signaling roles in all excitable cell types. There are four JPH isoforms, expressed primarily in muscle and neuronal cell types. Each JPH protein consists of 6 'membrane occupation and recognition nexus' (MORN) motifs, a joining region connecting these to another set of 2 MORN motifs, a putative alpha-helical region, a divergent region exhibiting low homology between JPH isoforms, and a carboxy-terminal transmembrane region anchoring into the ER/SR membrane. JPH isoforms play essential roles in developing and maintaining subcellular membrane junctions. Conversely, inherited mutations in JPH2 cause hypertrophic or dilated cardiomyopathy, while trinucleotide expansions in the JPH3 gene cause Huntington Disease-Like 2. Loss of JPH1 protein levels can cause skeletal myopathy, while loss of cardiac JPH2 levels causes heart failure and atrial fibrillation, among other disease. This review will provide a comprehensive overview of the JPH gene family, phylogeny, and evolutionary analysis of JPH genes and other MORN domain proteins. JPH biogenesis, membrane tethering, and binding partners will be discussed, as well as functional roles of JPH isoforms in excitable cells. Finally, potential roles of JPH isoform deficits in human disease pathogenesis will be reviewed.
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Affiliation(s)
- Stephan E Lehnart
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas, United States; Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Pediatrics (Cardiology), Neuroscience, and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, United States
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Cabrera-Serrano M, Caccavelli L, Savarese M, Vihola A, Jokela M, Johari M, Capiod T, Madrange M, Bugiardini E, Brady S, Quinlivan R, Merve A, Scalco R, Hilton-Jones D, Houlden H, Ibrahim Aydin H, Ceylaner S, Vockley J, Taylor RL, Folland C, Kelly A, Goullee H, Ylikallio E, Auranen M, Tyynismaa H, Udd B, Forrest ARR, Davis MR, Bratkovic D, Manton N, Robertson T, McCombe P, Laing NG, Phillips L, de Lonlay P, Ravenscroft G. Bi-allelic loss-of-function OBSCN variants predispose individuals to severe recurrent rhabdomyolysis. Brain 2021; 145:3985-3998. [DOI: 10.1093/brain/awab484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 12/04/2021] [Accepted: 12/10/2021] [Indexed: 11/14/2022] Open
Abstract
Abstract
Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, most cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified ten bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) predisposing individuals to recurrent rhabdomyolysis. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in SR function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in SR Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the SR and/or a decrease in Ca2+ SR storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.
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Affiliation(s)
- Macarena Cabrera-Serrano
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
- Unidad de Enfermedades Neuromusculares. Servicio de Neurologia y Neurofisiologia. Hospital Virgen del Rocio, Sevilla, Spain
| | - Laure Caccavelli
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Anna Vihola
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Tampere Neuromuscular Center, Tampere University Hospital, Tampere, Finland
| | - Manu Jokela
- Neuromuscular Research Center, Department of Neurology, Tampere University and University Hospital, Tampere, Finland
- Neurocenter, Department of Neurology, Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Thierry Capiod
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Marine Madrange
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Enrico Bugiardini
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - Stefen Brady
- Department of Neurology, Southmead Hospital, Bristol, UK
| | - Rosaline Quinlivan
- MRC Centre for Neuromuscular Diseases, University College Hospitals, London, UK
| | - Ashirwad Merve
- MRC Centre for Neuromuscular Diseases, University College Hospitals, London, UK
| | - Renata Scalco
- MRC Centre for Neuromuscular Diseases, University College Hospitals, London, UK
| | - David Hilton-Jones
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, UK
| | | | - Serdar Ceylaner
- Intergen Genetic Diagnosis and Research Center, Ankara, Turkey
| | - Jerry Vockley
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rhonda L. Taylor
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Chiara Folland
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Aasta Kelly
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
| | - Hayley Goullee
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Emil Ylikallio
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Mari Auranen
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Tampere Neuromuscular Center, Tampere University Hospital, Tampere, Finland
| | - Alistair R. R. Forrest
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Mark R. Davis
- Department of Diagnostic Genomics, PathWest Laboratory Medicine WA, Nedlands, WA, Australia
| | - Drago Bratkovic
- Metabolic Clinic, Women and Children’s Hospital, North Adelaide, SA, Australia
| | - Nicholas Manton
- SA Pathology, Women and Children’s Hospital, North Adelaide, SA, Australia
| | - Thomas Robertson
- Anatomical Pathology, Queensland Pathology, Brisbane, Queensland, Australia
| | - Pamela McCombe
- Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
- Centre for Clinical Research, The University of Queensland Centre for Clinical Research, Brisbane, Queensland, Australia
| | - Nigel G. Laing
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
- Department of Diagnostic Genomics, PathWest Laboratory Medicine WA, Nedlands, WA, Australia
| | - Liza Phillips
- SA Pathology, Women and Children’s Hospital, North Adelaide, SA, Australia
- The University of Adelaide, Adelaide, SA, Australia
| | - Pascale de Lonlay
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
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Fleming JR, Rani A, Kraft J, Zenker S, Börgeson E, Lange S. Exploring Obscurin and SPEG Kinase Biology. J Clin Med 2021; 10:jcm10050984. [PMID: 33801198 PMCID: PMC7957886 DOI: 10.3390/jcm10050984] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/10/2021] [Accepted: 02/18/2021] [Indexed: 12/15/2022] Open
Abstract
Three members of the obscurin protein family that contain tandem kinase domains with important signaling functions for cardiac and striated muscles are the giant protein obscurin, its obscurin-associated kinase splice isoform, and the striated muscle enriched protein kinase (SPEG). While there is increasing evidence for the specific roles that each individual kinase domain plays in cross-striated muscles, their biology and regulation remains enigmatic. Our present study focuses on kinase domain 1 and the adjacent low sequence complexity inter-kinase domain linker in obscurin and SPEG. Using Phos-tag gels, we show that the linker in obscurin contains several phosphorylation sites, while the same region in SPEG remained unphosphorylated. Our homology modeling, mutational analysis and molecular docking demonstrate that kinase 1 in obscurin harbors all key amino acids important for its catalytic function and that actions of this domain result in autophosphorylation of the protein. Our bioinformatics analyses also assign a list of putative substrates for kinase domain 1 in obscurin and SPEG, based on the known and our newly proposed phosphorylation sites in muscle proteins, including obscurin itself.
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Affiliation(s)
- Jennifer R. Fleming
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
- Correspondence: (J.R.F.); (E.B.); (S.L.)
| | - Alankrita Rani
- Centre for Molecular and Translational Medicine, The Wallenberg Laboratory and Wallenberg, Department of Molecular and Clinical Medicine, University of Gothenburg, 41345 Gothenburg, Sweden; (A.R.); (J.K.)
| | - Jamie Kraft
- Centre for Molecular and Translational Medicine, The Wallenberg Laboratory and Wallenberg, Department of Molecular and Clinical Medicine, University of Gothenburg, 41345 Gothenburg, Sweden; (A.R.); (J.K.)
| | - Sanja Zenker
- Department of Medicine, University of California, San Diego, CA 92093, USA;
| | - Emma Börgeson
- Centre for Molecular and Translational Medicine, The Wallenberg Laboratory and Wallenberg, Department of Molecular and Clinical Medicine, University of Gothenburg, 41345 Gothenburg, Sweden; (A.R.); (J.K.)
- Department of Clinical Physiology, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
- Correspondence: (J.R.F.); (E.B.); (S.L.)
| | - Stephan Lange
- Centre for Molecular and Translational Medicine, The Wallenberg Laboratory and Wallenberg, Department of Molecular and Clinical Medicine, University of Gothenburg, 41345 Gothenburg, Sweden; (A.R.); (J.K.)
- Department of Medicine, University of California, San Diego, CA 92093, USA;
- Correspondence: (J.R.F.); (E.B.); (S.L.)
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