title: Myosin VI facilitates connexin 43 gap junction accretion.
abstract: In this study, we demonstrate myosin VI enrichment at Cx43 (also known as GJA1)-containing gap junctions (GJs) in heart tissue, primary cardiomyocytes and cell culture models. In primary cardiac tissue and in fibroblasts from the myosin VI-null mouse as well as in tissue culture cells transfected with siRNA against myosin VI, we observe reduced GJ plaque size with a concomitant reduction in intercellular communication, as shown by fluorescence recovery after photobleaching (FRAP) and a new method of selective calcein administration. Analysis of the molecular role of myosin VI in Cx43 trafficking indicates that myosin VI is dispensable for the delivery of Cx43 to the cell surface and connexon movement in the plasma membrane. Furthermore, we cannot corroborate clathrin or Dab2 localization at gap junctions and we do not observe a function for the myosin-VI-Dab2 complex in clathrin-dependent endocytosis of annular gap junctions. Instead, we found that myosin VI was localized at the edge of Cx43 plaques by using total internal reflection fluorescence (TIRF) microscopy and use FRAP to identify a plaque accretion defect as the primary manifestation of myosin VI loss in Cx43 homeostasis. A fuller understanding of this derangement may explain the cardiomyopathy or gliosis associated with the loss of myosin VI.
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.|Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, UK.
authors.forename: Bennett J
authors.initials: BJ
authors.lastname: Waxse
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
authors.forename: Prabuddha
authors.identifier: 0000-0001-7094-6967
authors.initials: P
authors.lastname: Sengupta
authors.affiliation: Mount Sinai Hospital, Lunenfeld-Tanenbaum Research Institute, Toronto, Ontario M5G 1X5, Canada.
authors.forename: Geoffrey G
authors.identifier: 0000-0002-5570-7615
authors.initials: GG
authors.lastname: Hesketh
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA lippincottschwartzj@janelia.hhmi.org fb207@cam.ac.uk.
authors.forename: Jennifer
authors.identifier: 0000-0002-8601-3501
authors.initials: J
authors.lastname: Lippincott-Schwartz
authors.affiliation: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, UK lippincottschwartzj@janelia.hhmi.org fb207@cam.ac.uk.
authors.forename: Folma
authors.identifier: 0000-0003-4457-3479
authors.initials: F
authors.lastname: Buss
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D002450:Cell Communication; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000378:metabolism*; D000072417:Protein Domains; D021381:Protein Transport; D051381:Rats
chemical_list: D018031:Connexin 43; C089785:myosin VI; D018995:Myosin Heavy Chains
keywords: Connexin; Endocytosis; Gap junction; Myosin