title: Direct interaction of CaVβ with actin up-regulates L-type calcium currents in HL-1 cardiomyocytes.
abstract: Expression of the β-subunit (CaVβ) is required for normal function of cardiac L-type calcium channels, and its up-regulation is associated with heart failure. CaVβ binds to the α1 pore-forming subunit of L-type channels and augments calcium current density by facilitating channel opening and increasing the number of channels in the plasma membrane, by a poorly understood mechanism. Actin, a key component of the intracellular trafficking machinery, interacts with Src homology 3 domains in different proteins. Although CaVβ encompasses a highly conserved Src homology 3 domain, association with actin has not yet been explored. Here, using co-sedimentation assays and FRET experiments, we uncover a direct interaction between CaVβ and actin filaments. Consistently, single-molecule localization analysis reveals streaklike structures composed by CaVβ2 that distribute over several micrometers along actin filaments in HL-1 cardiomyocytes. Overexpression of CaVβ2-N3 in HL-1 cells induces an increase in L-type current without altering voltage-dependent activation, thus reflecting an increased number of channels in the plasma membrane. CaVβ mediated L-type up-regulation, and CaVβ-actin association is prevented by disruption of the actin cytoskeleton with cytochalasin D. Our study reveals for the first time an interacting partner of CaVβ that is directly involved in vesicular trafficking. We propose a model in which CaVβ promotes anterograde trafficking of the L-type channels by anchoring them to actin filaments in their itinerary to the plasma membrane.
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Stölting
authors.affiliation: the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany.
authors.forename: Regina Campos
authors.initials: RC
authors.lastname: de Oliveira
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Raul E
authors.initials: RE
authors.lastname: Guzman
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Erick
authors.initials: E
authors.lastname: Miranda-Laferte
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Rachel
authors.initials: R
authors.lastname: Conrad
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Nadine
authors.initials: N
authors.lastname: Jordan
authors.affiliation: the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Schmidt
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Johnny
authors.initials: J
authors.lastname: Hendriks
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gensch
authors.affiliation: From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and. Electronic address: pa.hidalgo@fz-juelich.de.
authors.forename: Patricia
authors.initials: P
authors.lastname: Hidalgo
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism; D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D020746:Calcium Channels, L-Type / Q000096:biosynthesis* / Q000235:genetics; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D015638:Cytochalasin D / Q000494:pharmacology; D051379:Mice; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D051381:Rats; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*; D018909:src Homology Domains
chemical_list: D000199:Actins; C491528:Cacnb2 protein, mouse; C491527:Cacnb2 protein, rat; D020746:Calcium Channels, L-Type; D019384:Nucleic Acid Synthesis Inhibitors; D015638:Cytochalasin D
keywords: Actin; Calcium Channel; Cardiac Muscle; Fluorescence Resonance Energy Transfer (FRET); Trafficking