title: Regulation of T-type calcium channels by Rho-associated kinase.
abstract: We investigated the regulation of T-type channels by Rho-associated kinase (ROCK). Activation of ROCK via the endogenous ligand lysophosphatidic acid (LPA) reversibly inhibited the peak current amplitudes of rat Ca(v)3.1 and Ca(v)3.3 channels without affecting the voltage dependence of activation or inactivation, whereas Ca(v)3.2 currents showed depolarizing shifts in these parameters. LPA-induced inhibition of Ca(v)3.1 was dependent on intracellular GTP, and was antagonized by treatment with ROCK and RhoA inhibitors, LPA receptor antagonists or GDPssS. Site-directed mutagenesis of the Ca(v)3.1 alpha1 subunit revealed that the ROCK-mediated effects involve two distinct phosphorylation consensus sites in the domain II-III linker. ROCK activation by LPA reduced native T-type currents in Y79 retinoblastoma and in lateral habenular neurons, and upregulated native Ca(v)3.2 current in dorsal root ganglion neurons. Our data suggest that ROCK is an important regulator of T-type calcium channels, with potentially far-reaching implications for multiple cell functions modulated by LPA.
authors.affiliation: Hotchkiss Brain Institute, Department of Physiology & Biophysics, University of Calgary, 3330 Hospital Drive N.W., Calgary, T2N 4N1, Canada.
authors.forename: Mircea
authors.initials: M
authors.lastname: Iftinca
authors.forename: Jawed
authors.initials: J
authors.lastname: Hamid
authors.forename: Lina
authors.initials: L
authors.lastname: Chen
authors.forename: Diego
authors.initials: D
authors.lastname: Varela
authors.forename: Reza
authors.initials: R
authors.lastname: Tadayonnejad
authors.forename: Christophe
authors.initials: C
authors.lastname: Altier
authors.forename: Ray W
authors.initials: RW
authors.lastname: Turner
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Zamponi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D020747:Calcium Channels, T-Type / Q000378:metabolism / Q000502:physiology*; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008246:Lysophospholipids / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D009474:Neurons / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D051381:Rats; D012175:Retinoblastoma / Q000378:metabolism; D013873:Thionucleotides / Q000378:metabolism; D054460:rho-Associated Kinases
chemical_list: C500994:Cacna1g protein, rat; C509958:Cacna1h protein, rat; D020747:Calcium Channels, T-Type; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D013873:Thionucleotides; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D006160:Guanosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; C032881:lysophosphatidic acid