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Postrigan AE, Babushkina NP, Svintsova LI, Plotnikova IV, Skryabin NA. Clinical and Genetic Characteristics of Congenital Long QT Syndrome. RUSS J GENET+ 2022. [DOI: 10.1134/s1022795422100064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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2
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Sancho M, Fletcher J, Welsh DG. Inward Rectifier Potassium Channels: Membrane Lipid-Dependent Mechanosensitive Gates in Brain Vascular Cells. Front Cardiovasc Med 2022; 9:869481. [PMID: 35419431 PMCID: PMC8995785 DOI: 10.3389/fcvm.2022.869481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Cerebral arteries contain two primary and interacting cell types, smooth muscle (SMCs) and endothelial cells (ECs), which are each capable of sensing particular hemodynamic forces to set basal tone and brain perfusion. These biomechanical stimuli help confer tone within arterial networks upon which local neurovascular stimuli function. Tone development is intimately tied to arterial membrane potential (VM) and changes in intracellular [Ca2+] driven by voltage-gated Ca2+ channels (VGCCs). Arterial VM is in turn set by the dynamic interplay among ion channel species, the strongly inward rectifying K+ (Kir) channel being of special interest. Kir2 channels possess a unique biophysical signature in that they strongly rectify, display negative slope conductance, respond to elevated extracellular K+ and are blocked by micromolar Ba2+. While functional Kir2 channels are expressed in both smooth muscle and endothelium, they lack classic regulatory control, thus are often viewed as a simple background conductance. Recent literature has provided new insight, with two membrane lipids, phosphatidylinositol 4,5-bisphosphate (PIP2) and cholesterol, noted to (1) stabilize Kir2 channels in a preferred open or closed state, respectively, and (2) confer, in association with the cytoskeleton, caveolin-1 (Cav1) and syntrophin, hemodynamic sensitivity. It is these aspects of vascular Kir2 channels that will be the primary focus of this review.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT, United States
- Department of Physiology, Faculty of Medicine, Universidad Complutense de Madrid, Madrid, Spain
- *Correspondence: Maria Sancho,
| | - Jacob Fletcher
- Department of Physiology and Pharmacology, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Donald G. Welsh
- Department of Physiology and Pharmacology, Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Donald G. Welsh,
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3
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Valera IC, Wacker AL, Hwang HS, Holmes C, Laitano O, Landstrom AP, Parvatiyar MS. Essential roles of the dystrophin-glycoprotein complex in different cardiac pathologies. Adv Med Sci 2021; 66:52-71. [PMID: 33387942 DOI: 10.1016/j.advms.2020.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 12/12/2020] [Accepted: 12/17/2020] [Indexed: 12/20/2022]
Abstract
The dystrophin-glycoprotein complex (DGC), situated at the sarcolemma dynamically remodels during cardiac disease. This review examines DGC remodeling as a common denominator in diseases affecting heart function and health. Dystrophin and the DGC serve as broad cytoskeletal integrators that are critical for maintaining stability of muscle membranes. The presence of pathogenic variants in genes encoding proteins of the DGC can cause absence of the protein and/or alterations in other complex members leading to muscular dystrophies. Targeted studies have allowed the individual functions of affected proteins to be defined. The DGC has demonstrated its dynamic function, remodeling under a number of conditions that stress the heart. Beyond genetic causes, pathogenic processes also impinge on the DGC, causing alterations in the abundance of dystrophin and associated proteins during cardiac insult such as ischemia-reperfusion injury, mechanical unloading, and myocarditis. When considering new therapeutic strategies, it is important to assess DGC remodeling as a common factor in various heart diseases. The DGC connects the internal F-actin-based cytoskeleton to laminin-211 of the extracellular space, playing an important role in the transmission of mechanical force to the extracellular matrix. The essential functions of dystrophin and the DGC have been long recognized. DGC based therapeutic approaches have been primarily focused on muscular dystrophies, however it may be a beneficial target in a number of disorders that affect the heart. This review provides an account of what we now know, and discusses how this knowledge can benefit persistent health conditions in the clinic.
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Affiliation(s)
- Isela C Valera
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Amanda L Wacker
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Hyun Seok Hwang
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Christina Holmes
- Department of Chemical and Biomedical Engineering, Florida A&M University-Florida State University College of Engineering, Tallahassee, FL, USA
| | - Orlando Laitano
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Andrew P Landstrom
- Department of Pediatrics, Division of Cardiology, Duke University School of Medicine, Durham, NC, USA; Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
| | - Michelle S Parvatiyar
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA.
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4
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Associating physiological functions with genomic variability in hibernating bats. Evol Ecol 2021. [DOI: 10.1007/s10682-020-10096-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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5
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Flavonoid Treatment of Breast Cancer Cells has Multifarious Consequences on Alpha-1-Syntrophin Expression and other Downstream Processes. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2020. [DOI: 10.1007/s13369-020-04508-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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6
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Detection of Inositol Phosphates by Split PH Domains. Methods Mol Biol 2019. [PMID: 31773569 DOI: 10.1007/978-1-0716-0167-9_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The pleckstrin homology (PH) domain is a family of structurally conserved proteins which can bind inositol phosphate derivatives. Some proteins involved in cellular signaling and cytoskeletal organization possess split PH domains that assemble into a structure which can bind specific inositol phosphates. Here we describe the design of split PH domain from a structurally well-characterized PH domain of phospholipase C (PLC) δ1 and Bruton's tyrosine kinase (Btk), which selectively bind Ins(1,4,5)P3 and Ins(1,3,4,5)P4, respectively. The PH domains fold into a functional structure when the split halves are brought to close proximity, and can be utilized to detect specific inositol phosphate of interest.
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7
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Bhat SS, Ali R, Khanday FA. Syntrophins entangled in cytoskeletal meshwork: Helping to hold it all together. Cell Prolif 2018; 52:e12562. [PMID: 30515904 DOI: 10.1111/cpr.12562] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/23/2018] [Accepted: 11/08/2018] [Indexed: 01/10/2023] Open
Abstract
Syntrophins are a family of 59 kDa peripheral membrane-associated adapter proteins, containing multiple protein-protein and protein-lipid interaction domains. The syntrophin family consists of five isoforms that exhibit specific tissue distribution, distinct sub-cellular localization and unique expression patterns implying their diverse functional roles. These syntrophin isoforms form multiple functional protein complexes and ensure proper localization of signalling proteins and their binding partners to specific membrane domains and provide appropriate spatiotemporal regulation of signalling pathways. Syntrophins consist of two PH domains, a PDZ domain and a conserved SU domain. The PH1 domain is split by the PDZ domain. The PH2 and the SU domain are involved in the interaction between syntrophin and the dystrophin-glycoprotein complex (DGC). Syntrophins recruit various signalling proteins to DGC and link extracellular matrix to internal signalling apparatus via DGC. The different domains of the syntrophin isoforms are responsible for modulation of cytoskeleton. Syntrophins associate with cytoskeletal proteins and lead to various cellular responses by modulating the cytoskeleton. Syntrophins are involved in many physiological processes which involve cytoskeletal reorganization like insulin secretion, blood pressure regulation, myogenesis, cell migration, formation and retraction of focal adhesions. Syntrophins have been implicated in various pathologies like Alzheimer's disease, muscular dystrophy, cancer. Their role in cytoskeletal organization and modulation makes them perfect candidates for further studies in various cancers and other ailments that involve cytoskeletal modulation. The role of syntrophins in cytoskeletal organization and modulation has not yet been comprehensively reviewed till now. This review focuses on syntrophins and highlights their role in cytoskeletal organization, modulation and dynamics via its involvement in different cell signalling networks.
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Affiliation(s)
- Sahar S Bhat
- Division of Biotechnology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Srinagar, India
| | - Roshia Ali
- Department of Biotechnology, University of Kashmir, Srinagar, India.,Department of Biochemistry, University of Kashmir, Srinagar, India
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Balke JE, Zhang L, Percival JM. Neuronal nitric oxide synthase (nNOS) splice variant function: Insights into nitric oxide signaling from skeletal muscle. Nitric Oxide 2018; 82:35-47. [PMID: 30503614 DOI: 10.1016/j.niox.2018.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 02/07/2023]
Abstract
Defects in neuronal nitric oxide synthase (nNOS) splice variant localization and signaling in skeletal muscle are a firmly established pathogenic characteristic of many neuromuscular diseases, including Duchenne and Becker muscular dystrophy (DMD and BMD, respectively). Therefore, substantial efforts have been made to understand and therapeutically target skeletal muscle nNOS isoform signaling. The purpose of this review is to summarize recent salient advances in understanding of the regulation, targeting, and function of nNOSμ and nNOSβ splice variants in normal and dystrophic skeletal muscle, primarily using findings from mouse models. The first focus of this review is how the differential targeting of nNOS splice variants creates spatially and functionally distinct nitric oxide (NO) signaling compartments at the sarcolemma, Golgi complex, and cytoplasm. Particular attention is given to the functions of sarcolemmal nNOSμ and limitations of current nNOS knockout models. The second major focus is to review current understanding of cGMP-mediated nNOS signaling in skeletal muscle and its emergence as a therapeutic target in DMD and BMD. Accordingly, we address the preclinical and clinical successes and setbacks with the testing of phosphodiesterase 5 inhibitors to redress nNOS signaling defects in DMD and BMD. In summary, this review of nNOS function in normal and dystrophic muscle aims to advance understanding how the messenger NO is harnessed for cellular signaling from a skeletal muscle perspective.
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Affiliation(s)
- Jordan E Balke
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine Miami, Florida, 33101, USA
| | - Ling Zhang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine Miami, Florida, 33101, USA
| | - Justin M Percival
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine Miami, Florida, 33101, USA.
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9
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Denti F, Paludan-Müller C, Olesen SP, Haunsø S, Svendsen JH, Olesen MS, Bentzen BH, Schmitt N. Functional consequences of genetic variation in sodium channel modifiers in early onset lone atrial fibrillation. Per Med 2018; 15:93-102. [DOI: 10.2217/pme-2017-0076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aim: We investigated the effect of variants in genes encoding sodium channel modifiers SNTA1 and GPD1L found in early onset atrial fibrillation (AF) patients. Patients & methods: Genetic screening in patients with early onset lone AF revealed three variants in GPD1L and SNTA1 in three AF patients. Functional analysis was performed by patch-clamp electrophysiology. Results: Co-expression of GPD1L or its p.A326E variant with NaV1.5 did not alter INa density or current kinetics. SNTA1 shifted the peak-current by -5 mV. The SNTA1-p.A257G variant significantly increased INa. SNTA1-p.P74L did not produce functional changes. Conclusion: Although genetic variation of sodium channel modifiers may contribute to development of AF at a molecular level, it is unlikely a monogenic cause of the disease.
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Affiliation(s)
- Federico Denti
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christian Paludan-Müller
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Søren-Peter Olesen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Jesper Hastrup Svendsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Morten Salling Olesen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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10
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Abstract
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. © 2017 American Physiological Society. Compr Physiol 7:891-944, 2017.
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Affiliation(s)
- Christine A Henderson
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Christopher G Gomez
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Stefanie M Novak
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Lei Mi-Mi
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
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11
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Aittaleb M, Martinez-Pena Y Valenzuela I, Akaaboune M. Spatial distribution and molecular dynamics of dystrophin glycoprotein components at the neuromuscular junction in vivo. J Cell Sci 2017; 130:1752-1759. [PMID: 28364093 DOI: 10.1242/jcs.198358] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/29/2017] [Indexed: 11/20/2022] Open
Abstract
A bimolecular fluorescence complementation (BiFC) approach was used to study the molecular interactions between different components of the postsynaptic protein complex at the neuromuscular junction of living mice. We show that rapsyn forms complex with both α-dystrobrevin and α-syntrophin at the crests of junctional folds. The linkage of rapsyn to α-syntrophin and/or α-dystrobrevin is mediated by utrophin, a protein localized at acetylcholine receptor (AChR)-rich domains. In mice deficient in α-syntrophin, in which utrophin is no longer present at the synapse, rapsyn interaction with α-dystrobrevin was completely abolished. This interaction was completely restored when either utrophin or α-syntrophin was introduced into muscles deficient in α-syntrophin. However, in neuromuscular junctions deficient in α-dystrobrevin, in which utrophin is retained, complex formation between rapsyn and α-syntrophin was unaffected. Using fluorescence recovery after photobleaching, we found that α-syntrophin turnover is 5-7 times faster than that of AChRs, and loss of α-dystrobrevin has no effect on rapsyn and α-syntrophin half-life, whereas the half-life of AChR was significantly altered. Altogether, these results provide new insights into the spatial distribution of dystrophin glycoprotein components and their dynamics in living mice.
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Affiliation(s)
- Mohamed Aittaleb
- Department of Molecular, Cellular, and Developmental Biology, and Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
| | - Isabel Martinez-Pena Y Valenzuela
- Department of Molecular, Cellular, and Developmental Biology, and Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
| | - Mohammed Akaaboune
- Department of Molecular, Cellular, and Developmental Biology, and Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA .,College of Sciences and Engineering, Life Science Division, Hamad Bin Khalifa University, Doha, Qatar
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12
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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13
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Actin depolymerization mediated loss of SNTA1 phosphorylation and Rac1 activity has implications on ROS production, cell migration and apoptosis. Apoptosis 2016; 21:737-48. [DOI: 10.1007/s10495-016-1241-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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14
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Allen DG, Whitehead NP, Froehner SC. Absence of Dystrophin Disrupts Skeletal Muscle Signaling: Roles of Ca2+, Reactive Oxygen Species, and Nitric Oxide in the Development of Muscular Dystrophy. Physiol Rev 2016; 96:253-305. [PMID: 26676145 DOI: 10.1152/physrev.00007.2015] [Citation(s) in RCA: 272] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Dystrophin is a long rod-shaped protein that connects the subsarcolemmal cytoskeleton to a complex of proteins in the surface membrane (dystrophin protein complex, DPC), with further connections via laminin to other extracellular matrix proteins. Initially considered a structural complex that protected the sarcolemma from mechanical damage, the DPC is now known to serve as a scaffold for numerous signaling proteins. Absence or reduced expression of dystrophin or many of the DPC components cause the muscular dystrophies, a group of inherited diseases in which repeated bouts of muscle damage lead to atrophy and fibrosis, and eventually muscle degeneration. The normal function of dystrophin is poorly defined. In its absence a complex series of changes occur with multiple muscle proteins showing reduced or increased expression or being modified in various ways. In this review, we will consider the various proteins whose expression and function is changed in muscular dystrophies, focusing on Ca(2+)-permeable channels, nitric oxide synthase, NADPH oxidase, and caveolins. Excessive Ca(2+) entry, increased membrane permeability, disordered caveolar function, and increased levels of reactive oxygen species are early changes in the disease, and the hypotheses for these phenomena will be critically considered. The aim of the review is to define the early damage pathways in muscular dystrophy which might be appropriate targets for therapy designed to minimize the muscle degeneration and slow the progression of the disease.
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Affiliation(s)
- David G Allen
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
| | - Nicholas P Whitehead
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
| | - Stanley C Froehner
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
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15
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Jeevaratnam K, Guzadhur L, Goh YM, Grace AA, Huang CLH. Sodium channel haploinsufficiency and structural change in ventricular arrhythmogenesis. Acta Physiol (Oxf) 2016; 216:186-202. [PMID: 26284956 DOI: 10.1111/apha.12577] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/11/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022]
Abstract
Normal cardiac excitation involves orderly conduction of electrical activation and recovery dependent upon surface membrane, voltage-gated, sodium (Na(+) ) channel α-subunits (Nav 1.5). We summarize experimental studies of physiological and clinical consequences of loss-of-function Na(+) channel mutations. Of these conditions, Brugada syndrome (BrS) and progressive cardiac conduction defect (PCCD) are associated with sudden, often fatal, ventricular tachycardia (VT) or fibrillation. Mouse Scn5a(+/-) hearts replicate important clinical phenotypes modelling these human conditions. The arrhythmic phenotype is associated not only with the primary biophysical change but also with additional, anatomical abnormalities, in turn dependent upon age and sex, each themselves exerting arrhythmic effects. Available evidence suggests a unified binary scheme for the development of arrhythmia in both BrS and PCCD. Previous biophysical studies suggested that Nav 1.5 deficiency produces a background electrophysiological defect compromising conduction, thereby producing an arrhythmic substrate unmasked by flecainide or ajmaline challenge. More recent reports further suggest a progressive decline in conduction velocity and increase in its dispersion particularly in ageing male Nav 1.5 haploinsufficient compared to WT hearts. This appears to involve a selective appearance of slow conduction at the expense of rapidly conducting pathways with changes in their frequency distributions. These changes were related to increased cardiac fibrosis. It is thus the combination of the structural and biophysical changes both accentuating arrhythmic substrate that may produce arrhythmic tendency. This binary scheme explains the combined requirement for separate, biophysical and structural changes, particularly occurring in ageing Nav 1.5 haploinsufficient males in producing clinical arrhythmia.
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Affiliation(s)
- K. Jeevaratnam
- Faculty of Health and Medical Science; University of Surrey; Guilford UK
- Perdana University - Royal College of Surgeons Ireland; Serdang Selangor Darul Ehsan Malaysia
| | - L. Guzadhur
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Niche Science & Technology; Richmond UK
| | - Y. M. Goh
- Department of Preclinical Sciences; Faculty of Veterinary Medicine; University Putra Malaysia; Serdang Selangor Darul Ehsan Malaysia
| | - A. A. Grace
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
| | - C. L.-H. Huang
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Physiological Laboratory; University of Cambridge; Cambridge UK
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16
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Dunn HA, Ferguson SSG. PDZ Protein Regulation of G Protein–Coupled Receptor Trafficking and Signaling Pathways. Mol Pharmacol 2015; 88:624-39. [DOI: 10.1124/mol.115.098509] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 03/25/2015] [Indexed: 01/03/2023] Open
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17
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Lee HJ, Kwon MH, Lee S, Hall RA, Yun CC, Choi I. Systematic family-wide analysis of sodium bicarbonate cotransporter NBCn1/SLC4A7 interactions with PDZ scaffold proteins. Physiol Rep 2014; 2:2/5/e12016. [PMID: 24844638 PMCID: PMC4098744 DOI: 10.14814/phy2.12016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
NBCn1 (SLC4A7) plays a role in transepithelial HCO3 (-) movement and intracellular pH maintenance in many tissues. In this study, we searched PDZ proteins capable of binding to NBCn1. We screened a protein array membrane, on which 96 different class I PDZ protein peptides were blotted, with the C-terminal domain of NBCn1 fused to GST. Thirteen proteins were identified in these screens: MAGI-3, NHERF-1, NHERF-2, PSD-95, chapsyn-110, ERBIN, MALS-1, densin-180, syntrophins α1, β2, γ2, MUPP1, and PDZK1. After determining these binding partners, we analyzed the database of known and predicted protein interactions to obtain an NBCn1 interaction network. The network shows NBCn1 being physically and functionally associated with a variety of membrane and cytosolic proteins via the binding partners. We then focused on syntrophin γ2 to examine the molecular and functional interaction between NBCn1 and one of the identified binding partners in the Xenopus oocyte expression system. GST/NBCn1 pulled down syntrophin γ2 and conversely GST/syntrophin γ2 pulled down NBCn1. Moreover, syntrophin γ2 increased intracellular pH recovery, from acidification, mediated by NBCn1's Na/HCO3 cotransport. Syntrophin γ2 also increased an ionic conductance produced by NBCn1 channel-like activity. Thus, syntrophin γ2 regulates NBCn1 activity. In conclusion, this study demonstrates that NBCn1 binds to many PDZ proteins, which in turn may allow the transporter to associate with other physiologically important proteins.
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Affiliation(s)
- Hye Jeong Lee
- Department of Pediatrics, Division of Hematology and Oncology, Vanderbilt University, Nashville, Tennessee, USA
| | - Min Hyung Kwon
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Soojung Lee
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Randy A Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - C Chris Yun
- Department of Medicine, Division of Digestive Disease, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Inyeong Choi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
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Dystrophin complex functions as a scaffold for signalling proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:635-42. [DOI: 10.1016/j.bbamem.2013.08.023] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 08/22/2013] [Accepted: 08/28/2013] [Indexed: 11/23/2022]
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20
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Adsit GS, Vaidyanathan R, Galler CM, Kyle JW, Makielski JC. Channelopathies from mutations in the cardiac sodium channel protein complex. J Mol Cell Cardiol 2013; 61:34-43. [PMID: 23557754 PMCID: PMC3720718 DOI: 10.1016/j.yjmcc.2013.03.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 03/15/2013] [Accepted: 03/21/2013] [Indexed: 12/19/2022]
Abstract
The cardiac sodium current underlies excitability in heart, and inherited abnormalities of the proteins regulating and conducting this current cause inherited arrhythmia syndromes. This review focuses on inherited mutations in non-pore forming proteins of sodium channel complexes that cause cardiac arrhythmia, and the deduced mechanisms by which they affect function and dysfunction of the cardiac sodium current. Defining the structure and function of these complexes and how they are regulated will contribute to understanding the possible roles for this complex in normal and abnormal physiology and homeostasis. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
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Affiliation(s)
- Graham S. Adsit
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Ravi Vaidyanathan
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Carla M. Galler
- School of Business and Applied Arts, Division of Visual Communication, Madison College, Madison, WI, USA 53704
| | - John W. Kyle
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Jonathan C. Makielski
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
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21
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Bhat HF, Adams ME, Khanday FA. Syntrophin proteins as Santa Claus: role(s) in cell signal transduction. Cell Mol Life Sci 2013; 70:2533-54. [PMID: 23263165 PMCID: PMC11113789 DOI: 10.1007/s00018-012-1233-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 11/21/2012] [Accepted: 12/03/2012] [Indexed: 11/30/2022]
Abstract
Syntrophins are a family of cytoplasmic membrane-associated adaptor proteins, characterized by the presence of a unique domain organization comprised of a C-terminal syntrophin unique (SU) domain and an N-terminal pleckstrin homology (PH) domain that is split by insertion of a PDZ domain. Syntrophins have been recognized as an important component of many signaling events, and they seem to function more like the cell's own personal 'Santa Claus' that serves to 'gift' various signaling complexes with precise proteins that they 'wish for', and at the same time care enough for the spatial, temporal control of these signaling events, maintaining overall smooth functioning and general happiness of the cell. Syntrophins not only associate various ion channels and signaling proteins to the dystrophin-associated protein complex (DAPC), via a direct interaction with dystrophin protein but also serve as a link between the extracellular matrix and the intracellular downstream targets and cell cytoskeleton by interacting with F-actin. They play an important role in regulating the postsynaptic signal transduction, sarcolemmal localization of nNOS, EphA4 signaling at the neuromuscular junction, and G-protein mediated signaling. In our previous work, we reported a differential expression pattern of alpha-1-syntrophin (SNTA1) protein in esophageal and breast carcinomas. Implicated in several other pathologies, like cardiac dys-functioning, muscular dystrophies, diabetes, etc., these proteins provide a lot of scope for further studies. The present review focuses on the role of syntrophins in membrane targeting and regulation of cellular proteins, while highlighting their relevance in possible development and/or progression of pathologies including cancer which we have recently demonstrated.
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Affiliation(s)
- Hina F Bhat
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India.
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22
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Fuhrmann-Stroissnigg H, Noiges R, Descovich L, Fischer I, Albrecht DE, Nothias F, Froehner SC, Propst F. The light chains of microtubule-associated proteins MAP1A and MAP1B interact with α1-syntrophin in the central and peripheral nervous system. PLoS One 2012; 7:e49722. [PMID: 23152929 PMCID: PMC3496707 DOI: 10.1371/journal.pone.0049722] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/17/2012] [Indexed: 12/24/2022] Open
Abstract
Microtubule-associated proteins of the MAP1 family (MAP1A, MAP1B, and MAP1S) share, among other features, a highly conserved COOH-terminal domain approximately 125 amino acids in length. We conducted a yeast 2-hybrid screen to search for proteins interacting with this domain and identified α1-syntrophin, a member of a multigene family of adapter proteins involved in signal transduction. We further demonstrate that the interaction between the conserved COOH-terminal 125-amino acid domain (which is located in the light chains of MAP1A, MAP1B, and MAP1S) and α1-syntrophin is direct and occurs through the pleckstrin homology domain 2 (PH2) and the postsynaptic density protein 95/disk large/zonula occludens-1 protein homology domain (PDZ) of α1-syntrophin. We confirmed the interaction of MAP1B and α1-syntrophin by co-localization of the two proteins in transfected cells and by co-immunoprecipitation experiments from mouse brain. In addition, we show that MAP1B and α1-syntrophin partially co-localize in Schwann cells of the murine sciatic nerve during postnatal development and in the adult. However, intracellular localization of α1-syntrophin and other Schwann cell proteins such as ezrin and dystrophin-related protein 2 (DRP2) and the localization of the axonal node of Ranvier-associated protein Caspr1/paranodin were not affected in MAP1B null mice. Our findings add to a growing body of evidence that classical MAPs are likely to be involved in signal transduction not only by directly modulating microtubule function, but also through their interaction with signal transduction proteins.
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Affiliation(s)
- Heike Fuhrmann-Stroissnigg
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Rainer Noiges
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Luise Descovich
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Irmgard Fischer
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
| | - Douglas E. Albrecht
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Fatiha Nothias
- INSERM U952, CNRS UMR 7224, Université Pierre et Marie Curie (UPMC) - Paris-06, Paris, France
| | - Stanley C. Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Friedrich Propst
- Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry and Cell Biology, Vienna, Austria
- * E-mail:
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Joe MK, Kee C, Tomarev SI. Myocilin interacts with syntrophins and is member of dystrophin-associated protein complex. J Biol Chem 2012; 287:13216-27. [PMID: 22371502 DOI: 10.1074/jbc.m111.224063] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Genetic studies have linked myocilin to open angle glaucoma, but the functions of the protein in the eye and other tissues have remained elusive. The purpose of this investigation was to elucidate myocilin function(s). We identified α1-syntrophin, a component of the dystrophin-associated protein complex (DAPC), as a myocilin-binding candidate. Myocilin interacted with α1-syntrophin via its N-terminal domain and co-immunoprecipitated with α1-syntrophin from C2C12 myotubes and mouse skeletal muscle. Expression of 15-fold higher levels of myocilin in the muscles of transgenic mice led to the elevated association of α1-syntrophin, neuronal nitric-oxide synthase, and α-dystroglycan with DAPC, which increased the binding of laminin to α-dystroglycan and Akt signaling. Phosphorylation of Akt and Forkhead box O-class 3, key regulators of muscle size, was increased more than 3-fold, whereas the expression of muscle-specific RING finger protein-1 and atrogin-1, muscle atrophy markers, was decreased by 79 and 88%, respectively, in the muscles of transgenic mice. Consequently, the average size of muscle fibers of the transgenic mice was increased by 36% relative to controls. We suggest that intracellular myocilin plays a role as a regulator of muscle hypertrophy pathways, acting through the components of DAPC.
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Affiliation(s)
- Myung Kuk Joe
- Retinal Ganglion Cell Biology Section, Laboratory of Retinal Cell and Molecular Biology, NEI, National Institutes of Health, Bethesda, Maryland 20892, USA
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Kim MJ, Froehner SC, Adams ME, Kim HS. α-Syntrophin is required for the hepatocyte growth factor-induced migration of cultured myoblasts. Exp Cell Res 2011; 317:2914-24. [PMID: 22001117 DOI: 10.1016/j.yexcr.2011.09.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 09/28/2011] [Accepted: 09/29/2011] [Indexed: 01/13/2023]
Abstract
Syntrophins are adaptor proteins that link intracellular signaling molecules to the dystrophin based scaffold. In this study, we investigated the function of syntrophins in cell migration, one of the early steps in myogenic differentiation and in regeneration of adult muscle. Hepatocyte growth factor (HGF) stimulates migration and lamellipodia formation in cultured C2 myoblasts. In the migrating cells, syntrophin concentrated in the rear-lateral region of the cell, opposite of the lamellipodia, instead of being diffusely present throughout the cytoplasm of non-migrating cells. When the expression of α-syntrophin, the major syntrophin isoform of skeletal muscle, was reduced by transfection with the α-syntrophin-specific siRNA, HGF stimulation of lamellipodia formation was prevented. Likewise, migration of myoblasts from α-syntrophin knockout mice could not be stimulated by HGF. However, HGF-induced migration was restored in myoblasts isolated from a transgenic mouse expressing α-syntrophin only in muscle cells. Treatment of C2 myoblasts with inhibitors of PI3-kinase not only reduced the rate of cell migration, but also impaired the accumulation of syntrophins in the rear-lateral region of the migrating cells. Phosphorylation of Akt was reduced in the α-syntrophin siRNA-treated C2 cells. These results suggest that α-syntrophin is required for HGF-induced migration of myoblasts and for proper PI3-kinase/Akt signaling.
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Affiliation(s)
- Min Jeong Kim
- Department of Biological Science, Ajou University, Suwon 443-749, Republic of Korea
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25
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Nakamori M, Takahashi MP. The role of α-dystrobrevin in striated muscle. Int J Mol Sci 2011; 12:1660-71. [PMID: 21673914 PMCID: PMC3111625 DOI: 10.3390/ijms12031660] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/29/2011] [Accepted: 02/23/2011] [Indexed: 12/29/2022] Open
Abstract
Muscular dystrophies are a group of diseases that primarily affect striated muscle and are characterized by the progressive loss of muscle strength and integrity. Major forms of muscular dystrophies are caused by the abnormalities of the dystrophin glycoprotein complex (DGC) that plays crucial roles as a structural unit and scaffolds for signaling molecules at the sarcolemma. α-Dystrobrevin is a component of the DGC and directly associates with dystrophin. α-Dystrobrevin also binds to intermediate filaments as well as syntrophin, a modular adaptor protein thought to be involved in signaling. Although no muscular dystrophy has been associated within mutations of the α-dystrobrevin gene, emerging findings suggest potential significance of α-dystrobrevin in striated muscle. This review addresses the functional role of α-dystrobrevin in muscle as well as its possible implication for muscular dystrophy.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2, D-4, Yamadaoka, Suita, Osaka 565-0871, Japan; E-Mail:
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 645 URMC, Rochester, NY 14642, USA
| | - Masanori P. Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2, D-4, Yamadaoka, Suita, Osaka 565-0871, Japan; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-6-6879-3571; Fax: +81-6-6879-3579
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26
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Hafner A, Obermajer N, Kos J. γ-1-syntrophin mediates trafficking of γ-enolase towards the plasma membrane and enhances its neurotrophic activity. Neurosignals 2011; 18:246-58. [PMID: 21358174 DOI: 10.1159/000324292] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 01/13/2011] [Indexed: 12/29/2022] Open
Abstract
Syntrophins are scaffold proteins that can bind several signaling molecules and localize them to the plasma membrane. We demonstrate here that in neuroblastoma SH-SY5Y cells, brain-specific γ1-syntrophin binds the neurotrophic factor γ-enolase through its PDZ domain, and translocates it to the plasma membrane, as shown by immunoprecipitation, surface plasmon resonance, fluorescence colocalization and flow cytometry. Extensive colocalization of γ1-syntrophin and γ-enolase was observed in neurite growth cones in differentiated SH-SY5Y cells. Silencing of the γ1-syntrophin gene by RNA interference significantly reduced the re-distribution of γ-enolase to the plasma membrane and impaired its neurotrophic effects. We demonstrated that an intact C-terminal end of γ-enolase is essential for its γ1-syntrophin-assisted trafficking. The cleavage of two amino acids at the C-terminal end of γ-enolase by the carboxypeptidase cathepsin X prevents binding with the γ1-syntrophin PDZ domain. Collectively, these data demonstrate that γ1-syntrophin participates in γ-enolase translocation towards the plasma membrane, a pre-requisite for its neurotrophic activity. By disrupting this γ1-syntrophin-guided subcellular distribution, cathepsin X reduces γ-enolase-induced neurotrophic signaling.
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Affiliation(s)
- Anja Hafner
- Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
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27
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Abstract
The dystrophin protein complex, an important regulator of muscle membrane integrity, also maintains neural organization through interactions with the L1CAM family member SAX-7. The dystrophin protein complex (DPC), composed of dystrophin and associated proteins, is essential for maintaining muscle membrane integrity. The link between mutations in dystrophin and the devastating muscle failure of Duchenne’s muscular dystrophy (DMD) has been well established. Less well appreciated are the accompanying cognitive impairment and neuropsychiatric disorders also presented in many DMD patients, which suggest a wider role for dystrophin in membrane–cytoskeleton function. This study provides genetic evidence of a novel role for DYS-1/dystrophin in maintaining neural organization in Caenorhabditis elegans. This neuronal function is distinct from the established role of DYS-1/dystrophin in maintaining muscle integrity and regulating locomotion. SAX-7, an L1 cell adhesion molecule (CAM) homologue, and STN-2/γ-syntrophin also function to maintain neural integrity in C. elegans. This study provides biochemical data that show that SAX-7 associates with DYS-1 in an STN-2/γ-syntrophin–dependent manner. These results reveal a recruitment of L1CAMs to the DPC to ensure neural integrity is maintained.
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Affiliation(s)
- Shan Zhou
- Department of Genetics, Cell Biology, and Development, Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
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28
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Α-syntrophin modulates myogenin expression in differentiating myoblasts. PLoS One 2010; 5:e15355. [PMID: 21179410 PMCID: PMC3003685 DOI: 10.1371/journal.pone.0015355] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 11/11/2010] [Indexed: 11/26/2022] Open
Abstract
Background α-Syntrophin is a scaffolding protein linking signaling proteins to the sarcolemmal dystrophin complex in mature muscle. However, α-syntrophin is also expressed in differentiating myoblasts during the early stages of muscle differentiation. In this study, we examined the relationship between the expression of α-syntrophin and myogenin, a key muscle regulatory factor. Methods and Findings The absence of α-syntrophin leads to reduced and delayed myogenin expression. This conclusion is based on experiments using muscle cells isolated from α-syntrophin null mice, muscle regeneration studies in α-syntrophin null mice, experiments in Sol8 cells (a cell line that expresses only low levels of α-syntrophin) and siRNA studies in differentiating C2 cells. In primary cultured myocytes isolated from α-syntrophin null mice, the level of myogenin was less than 50% that from wild type myocytes (p<0.005) 40 h after differentiation induction. In regenerating muscle, the expression of myogenin in the α-syntrophin null muscle was reduced to approximately 25% that of wild type muscle (p<0.005). Conversely, myogenin expression is enhanced in primary cultures of myoblasts isolated from a transgenic mouse over-expressing α-syntrophin and in Sol8 cells transfected with a vector to over-express α-syntrophin. Moreover, we find that myogenin mRNA is reduced in the absence of α-syntrophin and increased by α-syntrophin over-expression. Immunofluorescence microscopy shows that α-syntrophin is localized to the nuclei of differentiating myoblasts. Finally, immunoprecipitation experiments demonstrate that α-syntrophin associates with Mixed-Lineage Leukemia 5, a regulator of myogenin expression. Conclusions We conclude that α-syntrophin plays an important role in regulating myogenesis by modulating myogenin expression.
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29
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Bhat HF, Baba RA, Bashir M, Saeed S, Kirmani D, Wani MM, Wani NA, Wani KA, Khanday FA. Alpha-1-syntrophin protein is differentially expressed in human cancers. Biomarkers 2010; 16:31-6. [DOI: 10.3109/1354750x.2010.522731] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Albesa M, Ogrodnik J, Rougier JS, Abriel H. Regulation of the cardiac sodium channel Nav1.5 by utrophin in dystrophin-deficient mice. Cardiovasc Res 2010; 89:320-8. [DOI: 10.1093/cvr/cvq326] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Schubert S, Knoch KP, Ouwendijk J, Mohammed S, Bodrov Y, Jäger M, Altkrüger A, Wegbrod C, Adams ME, Kim Y, Froehner SC, Jensen ON, Kalaidzidis Y, Solimena M. β2-Syntrophin is a Cdk5 substrate that restrains the motility of insulin secretory granules. PLoS One 2010; 5:e12929. [PMID: 20886068 PMCID: PMC2944849 DOI: 10.1371/journal.pone.0012929] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 08/23/2010] [Indexed: 11/18/2022] Open
Abstract
The molecular basis for the interaction of insulin granules with the cortical cytoskeleton of pancreatic β-cells remains unknown. We have proposed that binding of the granule protein ICA512 to the PDZ domain of β2-syntrophin anchors granules to actin filaments and that the phosphorylation/dephosphorylation of β2-syntrophin regulates this association. Here we tested this hypothesis by analyzing INS-1 cells expressing GFP-β2-syntrophin through the combined use of biochemical approaches, imaging studies by confocal and total internal reflection fluorescence microscopy as well as electron microscopy. Our results support the notion that β2-syntrophin restrains the mobility of cortical granules in insulinoma INS-1 cells, thereby reducing insulin secretion and increasing insulin stores in resting cells, while increasing insulin release upon stimulation. Using mass spectrometry, in vitro phosphorylation assays and β2-syntrophin phosphomutants we found that phosphorylation of β2-syntrophin on S75 near the PDZ domain decreases its binding to ICA512 and correlates with increased granule motility, while phosphorylation of S90 has opposite effects. We further show that Cdk5, which regulates insulin secretion, phosphorylates S75. These findings provide mechanistic insight into how stimulation displaces insulin granules from cortical actin, thus promoting their motility and exocytosis.
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Affiliation(s)
- Sandra Schubert
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Klaus-Peter Knoch
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Joke Ouwendijk
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Shabaz Mohammed
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Yury Bodrov
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Melanie Jäger
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Anke Altkrüger
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Carolin Wegbrod
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Marvin E. Adams
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Yong Kim
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, United States of America
| | - Stanley C. Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Ole N. Jensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Yannis Kalaidzidis
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Michele Solimena
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail:
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Chen L, Zhou S. "CRASH"ing with the worm: insights into L1CAM functions and mechanisms. Dev Dyn 2010; 239:1490-501. [PMID: 20225255 DOI: 10.1002/dvdy.22269] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The L1 family of cell adhesion molecules (L1CAMs) in vertebrates has long been studied for its roles in nervous system development and function. Members of this family have been associated with distinct neurological disorders that include CRASH, autism, 3p syndrome, and schizophrenia. The conservation of L1CAMs in Drosophila and Caenorhabditis elegans allows the opportunity to take advantage of these simple model organisms and their accessible genetic manipulations to dissect L1CAM functions and mechanisms of action. This review summarizes the discoveries of L1CAMs made in C. elegans, showcasing this simple model organism as a powerful system to uncover L1CAM mechanisms and roles in healthy and diseased states.
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Affiliation(s)
- Lihsia Chen
- Department of Genetics, Cell Biology, and Development, Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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De Arcangelis V, Serra F, Cogoni C, Vivarelli E, Monaco L, Naro F. β1-syntrophin modulation by miR-222 in mdx mice. PLoS One 2010; 5:e12098. [PMID: 20856896 PMCID: PMC2938373 DOI: 10.1371/journal.pone.0012098] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 07/18/2010] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND In mdx mice, the absence of dystrophin leads to the deficiency of other components of the dystrophin-glycoprotein complex (DAPC), making skeletal muscle fibers more susceptible to necrosis. The mechanisms involved in the disappearance of the DAPC are not completely understood. The muscles of mdx mice express normal amounts of mRNA for the DAPC components, thus suggesting post-transcriptional regulation. METHODOLOGY/PRINCIPAL FINDINGS We investigated the hypothesis that DAPC reduction could be associated with the microRNA system. Among the possible microRNAs (miRs) found to be upregulated in the skeletal muscle tissue of mdx compared to wt mice, we demonstrated that miR-222 specifically binds to the 3'-UTR of β1-syntrophin and participates in the downregulation of β1-syntrophin. In addition, we documented an altered regulation of the 3'-UTR of β1-syntrophin in muscle tissue from dystrophic mice. CONCLUSION/SIGNIFICANCE These results show the importance of the microRNA system in the regulation of DAPC components in dystrophic muscle, and suggest a potential role of miRs in the pathophysiology of dystrophy.
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Affiliation(s)
| | - Filippo Serra
- Department of Histology and Medical Embryology, University Sapienza, Rome, Italy
| | - Carlo Cogoni
- Department of Cellular Biotechnology and Ematology, University Sapienza, Rome, Italy
| | - Elisabetta Vivarelli
- Department of Histology and Medical Embryology, University Sapienza, Rome, Italy
| | - Lucia Monaco
- Department of Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Fabio Naro
- Department of Histology and Medical Embryology, University Sapienza, Rome, Italy
- IIM, Pavia, Italy
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Nagai R, Hashimoto R, Yamaguchi M. Drosophila Syntrophins are involved in locomotion and regulation of synaptic morphology. Exp Cell Res 2010; 316:2313-21. [PMID: 20632467 DOI: 10.1016/j.yexcr.2010.05.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Syntrophin components of the dystrophin glycoprotein complex (DGC) feature multiple protein interaction domains that may act in molecular scaffolding, recruiting signaling proteins to membranes and the DGC. Drosophila Syntrophin-1 (Syn1) and Syntrophin-2 (Syn2) are counterparts of human alpha1/beta1/beta2-syntrophins and gamma1/gamma2-syntrophins, respectively. alpha1/beta1/beta2-syntrophins are well documented, while little is known about gamma1/gamma2-syntrophins. Here, we performed immunohistochemical analyses with a specific antibody to Syn2 and demonstrated predominant expression in the larval and adult central nervous system. To investigate the in vivo functions of Syn2, we have generated Drosophila Syn2 deficiency mutants. Although the Syn2 mutants exhibit no overt phenotype, the combination of Syn1 knockdown and Syn2(37) mutation dramatically shortened life span, synergistically reduced locomotion ability and synergistically enhanced overgrowth of neuromuscular junctions in N-ethylmaleimide sensitive factor 2 mutants. From these data we conclude that Syn1 and Syn2 are required for locomotion and are involved in regulation of synaptic morphology. In addition, the two syntrophins can at least partially compensate for each other's functions.
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Affiliation(s)
- Rika Nagai
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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Aquaporin expression in normal and pathological skeletal muscles: a brief review with focus on AQP4. J Biomed Biotechnol 2010; 2010:731569. [PMID: 20339523 PMCID: PMC2842974 DOI: 10.1155/2010/731569] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 01/12/2010] [Accepted: 01/17/2010] [Indexed: 11/30/2022] Open
Abstract
Freeze-fracture electron microscopy enabled us to observe the molecular architecture of the biological membranes. We were studying the myofiber plasma membranes of health and disease by using this technique and were interested in the special assembly called orthogonal arrays (OAs). OAs were present in normal myofiber plasma membranes and were especially numerous in fast twitch type 2 myofibers; while OAs were lost from sarcolemmal plasma membranes of severely affected muscles with dystrophinopathy and dysferlinopathy but not with caveolinopathy. In the mid nineties of the last century, the OAs turned out to be a water channel named aquaporin 4 (AQP4). Since this discovery, several groups of investigators have been studying AQP4 expression in diseased muscles. This review summarizes the papers which describe the expression of OAs, AQP4, and other AQPs at the sarcolemma of healthy and diseased muscle and discusses the possible role of AQPs, especially that of AQP4, in normal and pathological skeletal muscles.
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Several dystrophin-glycoprotein complex members are present in crude surface membranes but they are sodium dodecyl sulphate invisible in KCl-washed microsomes from mdx mouse muscle. Cell Mol Biol Lett 2009; 15:134-52. [PMID: 19997781 PMCID: PMC6276006 DOI: 10.2478/s11658-009-0039-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 11/27/2009] [Indexed: 11/20/2022] Open
Abstract
The dystrophin-glycoprotein complex (DGC) is a large trans-sarcolemmal complex that provides a linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. In skeletal muscle, it consists of the dystroglycan, sarcoglycan and cytoplasmic complexes, with dystrophin forming the core protein. The DGC has been described as being absent or greatly reduced in dystrophin-deficient muscles, and this lack is considered to be involved in the dystrophic phenotype. Such a decrease in the DGC content was observed in dystrophin-deficient muscle from humans with muscular dystrophy and in mice with X-linked muscular dystrophy (mdx mice). These deficits were observed in total muscle homogenates and in partially membrane-purified muscle fractions, the so-called KCl-washed microsomes. Here, we report that most of the proteins of the DGC are actually present at normal levels in the mdx mouse muscle plasma membrane. The proteins are detected in dystrophic animal muscles when the immunoblot assay is performed with crude surface membrane fractions instead of the usually employed KCl-washed microsomes. We propose that these proteins form SDS-insoluble membrane complexes when dystrophin is absent.
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37
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Hedley PL, Jørgensen P, Schlamowitz S, Wangari R, Moolman-Smook J, Brink PA, Kanters JK, Corfield VA, Christiansen M. The genetic basis of long QT and short QT syndromes: A mutation update. Hum Mutat 2009; 30:1486-511. [DOI: 10.1002/humu.21106] [Citation(s) in RCA: 318] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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38
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Syntrophin-2 is required for eye development in Drosophila. Exp Cell Res 2009; 316:272-85. [PMID: 19836389 DOI: 10.1016/j.yexcr.2009.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 09/07/2009] [Accepted: 10/07/2009] [Indexed: 11/23/2022]
Abstract
Syntrophins are components of the dystrophin glycoprotein complex (DGC), which is encoded by causative genes of muscular dystrophies. The DGC is thought to play roles not only in linking the actin cytoskeleton to the extracellular matrix, providing stability to the cell membrane, but also in signal transduction. Because of their binding to a variety of different molecules, it has been suggested that syntrophins are adaptor proteins recruiting signaling proteins to membranes and the DGC. However, critical roles in vivo remain elusive. Drosophila Syntrophin-2 (Syn2) is an orthologue of human gamma 1/gamma 2-syntrophins. Western immunoblot analysis here showed Syn2 to be expressed throughout development, with especially high levels in the adult head. Morphological aberrations were observed in Syn2 knockdown adult flies, with lack of retinal elongation and malformation of rhabdomeres. Furthermore, Syn2 knockdown flies exhibited excessive apoptosis in third instar larvae and alterations in the actin localization in the pupal retinae. Genetic crosses with a collection of Drosophila deficiency stocks allowed us to identify seven genomic regions, deletions of which caused enhancement of the rough eye phenotype induced by Syn2 knockdown. This information should facilitate identification of Syn2 regulators in Drosophila and clarification of roles of Syn2 in eye development.
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Abstract
NOS is a key enzyme in the production of NO, a molecule that directly regulates vasorelaxation and blood supply. Diverse forms of muscle disease have been clinically associated with unusual fatigue after exercise. The localization of neuronal NOS (nNOS) at the plasma membrane of muscle has recently been shown to prevent muscle fatigue after exercise. In this issue of the JCI, Lai et al. show that dystrophin--the structural protein missing in individuals with Duchenne muscular dystrophy--anchors nNOS to the sarcolemma through a direct interaction with dystrophin spectrin-like repeats 16 and 17 (see the related article, doi:10.1172/JCI36612). Furthermore, in another recently reported study of mouse models of muscular dystrophy, phosphodiesterase 5A inhibitors were used to treat the downstream ischemia that is associated with nNOS mislocalization. Collectively, these findings significantly advance our understanding of exercise-induced muscle fatigue and its role in muscle disease.
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Affiliation(s)
- Ahlke Heydemann
- Section of Cardiology, Department of Medicine, University of Chicago, 5841 S.Maryland, Chicago, IL 60637, USA
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40
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New insights into brain glutaminases: beyond their role on glutamatergic transmission. Neurochem Int 2009; 55:64-70. [PMID: 19428808 DOI: 10.1016/j.neuint.2009.02.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 02/18/2009] [Accepted: 02/27/2009] [Indexed: 01/29/2023]
Abstract
The synthesis of glutamate in brain must be exquisitely regulated because of its harmful potential giving rise to excitotoxic damage. In this sense, a stringent control based on multiple regulatory mechanisms should be expected to be exhibited by the biosynthetic enzymes responsible of glutamate generation, to assure that glutamate is only synthesized at the right place and at the right time. Glutaminase is considered as the main glutamate-producer enzyme in brain. Recently, novel glutaminase isoforms and extramitochondrial locations for these proteins have been discovered in the brain of mammals: identifying the function of each isozyme is essential for understanding the role of glutaminases in cerebral function. In addition, the interactome of glutaminases is starting to be uncovered adding a new level of regulatory complexity with important functional consequences, including selective and regulated targeting to concrete cellular locations. Finally, recent progress has identified glutaminase to be also present in astrocytes which precludes its classical consideration as a neuron-specific enzyme.
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González-Ramírez R, Morales-Lázaro SL, Tapia-Ramírez V, Mornet D, Cisneros B. Nuclear and nuclear envelope localization of dystrophin Dp71 and dystrophin-associated proteins (DAPs) in the C2C12 muscle cells: DAPs nuclear localization is modulated during myogenesis. J Cell Biochem 2008; 105:735-45. [PMID: 18680104 DOI: 10.1002/jcb.21870] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dystrophin and dystrophin-associated proteins (DAPs) form a complex around the sarcolemma, which gives stability to the sarcolemma and leads signal transduction. Recently, the nuclear presence of dystrophin Dp71 and DAPs has been revealed in different non-muscle cell types, opening the possibility that these proteins could also be present in the nucleus of muscle cells. In this study, we analyzed by Immunofluorescence assays and Immunoblotting analysis of cell fractions the subcellular localization of Dp71 and DAPs in the C(2)C(12) muscle cell line. We demonstrated the presence of Dp71, alpha-sarcoglycan, alpha-dystrobrevin, beta-dystroglycan and alpha-syntrophin not only in plasma membrane but also in the nucleus of muscle cells. In addition, we found by Immunoprecipitation assays that these proteins form a nuclear complex. Interestingly, myogenesis modulates the presence and/or relative abundance of DAPs in the plasma membrane and nucleus as well as the composition of the nuclear complex. Finally, we demonstrated the presence of Dp71, alpha-sarcoglycan, beta-dystroglycan, alpha-dystrobrevin and alpha-syntrophin in the C(2)C(12) nuclear envelope fraction. Interestingly, alpha-sarcoglycan and beta-dystroglycan proteins showed enrichment in the nuclear envelope, compared with the nuclear fraction, suggesting that they could function as inner nuclear membrane proteins underlying the secondary association of Dp71 and the remaining DAPs to the nuclear envelope. Nuclear envelope localization of Dp71 and DAPs might be involved in the nuclear envelope-associated functions, such as nuclear structure and modulation of nuclear processes.
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Affiliation(s)
- R González-Ramírez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Avenida Instituto Politécnico Nacional 2508, México, DF, Mexico
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42
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Abstract
PURPOSE OF REVIEW The lipid efflux pathway is important for both HDL formation and the reverse cholesterol transport pathway. This review is focused on recent findings on the mechanism of lipid efflux and its regulation, particularly in macrophages. RECENT FINDINGS Significant progress has been made on understanding the sequence of events that accompany the interaction of apolipoproteins A-I with cell surface ATP-binding cassette transporter A1 and its subsequent lipidation. Continued research on the regulation of ATP-binding cassette transporter A1 and ATP-binding cassette transporter G1 expression and traffic has also generated new paradigms for the control of lipid efflux from macrophages and its contribution to reverse cholesterol transport. In addition, the mobilization of cholesteryl esters from lipid droplets represents a new step in the control of cholesterol efflux. SUMMARY The synergy between lipid transporters is a work in progress, but its importance in reverse cholesterol transport is clear. The regulation of efflux implies both the regulation of relevant transporters and the cellular trafficking of cholesterol.
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Affiliation(s)
- Yves L Marcel
- Lipoprotein and Atherosclerosis Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
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Bunnell TM, Jaeger MA, Fitzsimons DP, Prins KW, Ervasti JM. Destabilization of the dystrophin-glycoprotein complex without functional deficits in alpha-dystrobrevin null muscle. PLoS One 2008; 3:e2604. [PMID: 18596960 PMCID: PMC2432020 DOI: 10.1371/journal.pone.0002604] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 06/03/2008] [Indexed: 11/20/2022] Open
Abstract
α-Dystrobrevin is a component of the dystrophin-glycoprotein complex (DGC) and is thought to have both structural and signaling roles in skeletal muscle. Mice deficient for α-dystrobrevin (adbn−/−) exhibit extensive myofiber degeneration and neuromuscular junction abnormalities. However, the biochemical stability of the DGC and the functional performance of adbn−/− muscle have not been characterized. Here we show that the biochemical association between dystrophin and β-dystroglycan is compromised in adbn−/− skeletal muscle, suggesting that α-dystrobrevin plays a structural role in stabilizing the DGC. However, despite muscle cell death and DGC destabilization, costamere organization and physiological performance is normal in adbn−/− skeletal muscle. Our results demonstrate that myofiber degeneration alone does not cause functional deficits and suggests that more complex pathological factors contribute to the development of muscle weakness in muscular dystrophy.
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Affiliation(s)
- Tina M. Bunnell
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Michele A. Jaeger
- Program in Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Daniel P. Fitzsimons
- Department of Physiology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Kurt W. Prins
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - James M. Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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Hijikata T, Nakamura A, Isokawa K, Imamura M, Yuasa K, Ishikawa R, Kohama K, Takeda S, Yorifuji H. Plectin 1 links intermediate filaments to costameric sarcolemma through β-synemin, α-dystrobrevin and actin. J Cell Sci 2008; 121:2062-74. [DOI: 10.1242/jcs.021634] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In skeletal muscles, the sarcolemma is possibly stabilized and protected against contraction-imposed stress by intermediate filaments (IFs) tethered to costameric sarcolemma. Although there is emerging evidence that plectin links IFs to costameres through dystrophin-glycoprotein complexes (DGC), the molecular organization from plectin to costameres still remains unclear. Here, we show that plectin 1, a plectin isoform expressed in skeletal muscle, can interact with β-synemin, actin and a DGC component, α-dystrobrevin, in vitro. Ultrastructurally, β-synemin molecules appear to be incorporated into costameric dense plaques, where they seem to serve as actin-associated proteins rather than IF proteins. In fact, they can bind actin and α-dystrobrevin in vitro. Moreover, in vivo immunoprecipitation analyses demonstrated that β-synemin- and plectin-immune complexes from lysates of muscle light microsomes contained α-dystrobrevin, dystrophin, nonmuscle actin, metavinculin, plectin and β-synemin. These findings suggest a model in which plectin 1 interacts with DGC and integrin complexes directly, or indirectly through nonmuscle actin and β-synemin within costameres. The DGC and integrin complexes would cooperate to stabilize and fortify the sarcolemma by linking the basement membrane to IFs through plectin 1, β-synemin and actin. Besides, the two complexes, together with plectin and IFs, might have their own functions as platforms for distinct signal transduction.
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Affiliation(s)
- Takao Hijikata
- Department of Anatomy and Cell Biology, Faculty of Pharmacy, Research Institute of Pharmaceutical Sciences, Musashino University, Tokyo 202-8585, Japan
| | - Akio Nakamura
- Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
| | - Keitaro Isokawa
- Department of Anatomy, Nihon University School of Dentistry, Tokyo 101-8310, Japan
| | - Michihiro Imamura
- Department of Molecular Therapy, National Institute of Neuroscience, NCNP, Tokyo 187-8502, Japan
| | - Katsutoshi Yuasa
- Department of Anatomy and Cell Biology, Faculty of Pharmacy, Research Institute of Pharmaceutical Sciences, Musashino University, Tokyo 202-8585, Japan
| | - Ryoki Ishikawa
- Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
| | - Kazuhiro Kohama
- Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
| | - Shinichi Takeda
- Department of Molecular Therapy, National Institute of Neuroscience, NCNP, Tokyo 187-8502, Japan
| | - Hiroshi Yorifuji
- Department of Anatomy, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
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45
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Olalla L, Gutiérrez A, Jiménez AJ, López-Téllez JF, Khan ZU, Pérez J, Alonso FJ, de la Rosa V, Campos-Sandoval JA, Segura JA, Aledo JC, Márquez J. Expression of the scaffolding PDZ protein glutaminase-interacting protein in mammalian brain. J Neurosci Res 2008; 86:281-92. [PMID: 17847083 DOI: 10.1002/jnr.21505] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A human brain cDNA clone coding for a novel PDZ-domain protein of 124 amino acids was previously isolated in our laboratory. The protein was termed glutaminase-interacting protein (GIP), because it interacts with the C-terminal region of the human L-type glutaminase (LGA). The pattern of expression and functions of GIP in brain are completely unknown, so its significance remains undefined. Here we describe the expression of GIP mRNA and protein in mammalian brain. Northern blot analysis revealed that GIP mRNA was ubiquitous in most regions of human brain but was particularly abundant in spinal cord. The presence of the protein in rat and monkey brain was studied at the regional, cellular, and subcellular level by immunocytochemistry. The protein was found to be present in both neurons and astrocytes, with a cytosolic and mitochondrial subcellular localization. Double immunofluorescence labeling with anti-GIP and anti-LGA antibodies using confocal microscopy revealed colocalization of both proteins in astrocyte cell processes and their perivascular end feet. Electron microscopy of rat brain neurons revealed GIP immunoreactivity concentrated also in the nuclear envelope and the plasma membrane. The multiple locations for GIP in mammalian brain are in agreement with known protein interaction partners reported for this PDZ protein. The findings presented here support a role of GIP as an important scaffold in both astrocytes and neurons and point toward astrocytic processes and perivascular end feet as plausible anatomical substrates for interaction with glutaminase.
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Affiliation(s)
- Lucía Olalla
- Departamento de Biología Molecular y Bioquímica, Universidad de Málaga, Málaga, Spain
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46
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA.
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47
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Ervasti JM, Sonnemann KJ. Biology of the striated muscle dystrophin-glycoprotein complex. INTERNATIONAL REVIEW OF CYTOLOGY 2008; 265:191-225. [PMID: 18275889 DOI: 10.1016/s0074-7696(07)65005-0] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Since its first description in 1990, the dystrophin-glycoprotein complex has emerged as a critical nexus for human muscular dystrophies arising from defects in a variety of distinct genes. Studies in mammals widely support a primary role for the dystrophin-glycoprotein complex in mechanical stabilization of the plasma membrane in striated muscle and provide hints for secondary functions in organizing molecules involved in cellular signaling. Studies in model organisms confirm the importance of the dystrophin-glycoprotein complex for muscle cell viability and have provided new leads toward a full understanding of its secondary roles in muscle biology.
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Affiliation(s)
- James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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48
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Okumura A, Nagai K, Okumura N. Interaction of α1-syntrophin with multiple isoforms of heterotrimeric G protein α subunits. FEBS J 2007; 275:22-33. [DOI: 10.1111/j.1742-4658.2007.06174.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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49
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Rees MLJ, Lien CF, Górecki DC. Dystrobrevins in muscle and non-muscle tissues. Neuromuscul Disord 2007; 17:123-34. [PMID: 17251025 DOI: 10.1016/j.nmd.2006.11.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Revised: 10/26/2006] [Accepted: 11/20/2006] [Indexed: 01/23/2023]
Abstract
The alpha- and beta-dystrobrevins belong to the family of dystrophin-related and dystrophin-associated proteins. As constituents of the dystrophin-associated protein complex, alpha-dystrobrevin was believed to have a role predominantly in muscles and beta-dystrobrevin in non-muscle tissues. Recent reports described novel localisations and molecular characteristics of alpha-dystrobrevin isoforms in non-muscle tissues (developing and adult). While single and double knockout studies have revealed distinct functions of dystrobrevin in some tissues, these also suggested a strong compensatory mechanism, where dystrobrevins displaying overlapping tissue expression pattern and structure/function similarity can substitute each other. No human disease has been unequivocally associated within mutations of dystrobrevin genes. However, some significant exceptions to these overlapping expression patterns, mainly in the brain, suggest that dystrobrevin mutations might underlie some specific motor, behavioural or cognitive defects. Dystrobrevin binding partner DTNBP1 (dysbindin) is a probable susceptibility gene for schizophrenia and bipolar affective disorder in some populations. As dysbindin abnormality is linked to Hermansky-Pudlak syndrome, dystrobrevins and/or their binding partners may also be required for proper function of other non-muscle tissues.
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Affiliation(s)
- Melissa L J Rees
- Department of Molecular Medicine, Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, UK
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50
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Vandebrouck A, Sabourin J, Rivet J, Balghi H, Sebille S, Kitzis A, Raymond G, Cognard C, Bourmeyster N, Constantin B. Regulation of capacitative calcium entries by α1‐syntrophin: association of TRPC1 with dystrophin complex and the PDZ domain of α1‐syntrophin. FASEB J 2007; 21:608-17. [PMID: 17202249 DOI: 10.1096/fj.06-6683com] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Calcium mishandling in Duchenne dystrophic muscle suggested that dystrophin, a membrane-associated cytoskeleton protein, might regulate calcium signaling cascade such as calcium influx pathway. It was previously shown that abnormal calcium entries involve uncontrolled stretch-activated currents and store-operated Ca2+ currents supported by TRPC1 channels. Moreover, our recent work demonstrated that reintroduction of minidystrophin in dystrophic myotubes restores normal capacitative calcium entries (CCEs). However, until now, no molecular link between the dystrophin complex and calcium entry channels has been described. This study is the first to show by coimmunoprecipitation assays the molecular association of TRPC1 with dystrophin and alpha1-syntrophin in muscle cells. TRPC1 was also associated with alpha1-syntrophin in dystrophic muscle cells independently of dystrophin. Furthermore, glutathione S-transferase (GST) pull-down assays showed that TRPC1 binds to the alpha1-syntrophin PDZ domain. Transfected recombinant alpha1-syntrophin formed a complex with TRPC1 channels and restored normal CCEs in dystrophic muscle cells. We suggest that normal regulation of CCEs in skeletal muscle depends on the association between TRPC1 channels and alpha1-syntrophin that may anchor the store-operated channels to the dystrophin-associated protein complex (DAPC). The loss of this molecular association could participate in the calcium alterations observed in dystrophic muscle cells. This study provides a new model for the regulation of calcium influx by interaction with the scaffold of the DAPC in muscle cells.
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Affiliation(s)
- Aurélie Vandebrouck
- Institut de Physiologie et Biologie Cellulaires, CNRS, UMR-6187, University of Poitiers, 86022 Poitiers, France
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