title: Store depletion induces Gαq-mediated PLCβ1 activity to stimulate TRPC1 channels in vascular smooth muscle cells.
abstract: Depletion of sarcoplasmic reticulum (SR) Ca(2+) stores activates store-operated channels (SOCs) composed of canonical transient receptor potential (TRPC) 1 proteins in vascular smooth muscle cells (VSMCs), which contribute to important cellular functions. We have previously shown that PKC is obligatory for activation of TRPC1 SOCs in VSMCs, and the present study investigates if the classic phosphoinositol signaling pathway involving Gαq-mediated PLC activity is responsible for driving PKC-dependent channel gating. The G-protein inhibitor GDP-β-S, anti-Gαq antibodies, the PLC inhibitor U73122, and the PKC inhibitor GF109203X all inhibited activation of TRPC1 SOCs, and U73122 and GF109203X also reduced store-operated PKC-dependent phosphorylation of TRPC1 proteins. Three distinct SR Ca(2+) store-depleting agents, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester, cyclopiazonic acid, and N,N,N',N'-tetrakis(2-pyridylmethyl)ethane-1,2-diamineed, induced translocations of the fluorescent biosensor GFP-PLCδ1-PH from the cell membrane to the cytosol, which were inhibited by U73122. Knockdown of PLCβ1 with small hairpin RNA reduced both store-operated PLC activity and stimulation of TRPC1 SOCs. Immunoprecipitation studies and proximity ligation assays revealed that store depletion induced interactions between TRPC1 and Gαq, and TRPC1 and PLCβ1. We propose a novel activation mechanism for TRPC1 SOCs in VSMCs, in which store depletion induces formation of TRPC1-Gαq-PLCβ1 complexes that lead to PKC stimulation and channel gating.
authors.affiliation: *Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, and Institute of Medical and Biomedical Education, St. George's, University of London, London, United Kingdom; and Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA jshi@sgul.ac.uk.
authors.forename: Jian
authors.initials: J
authors.lastname: Shi
authors.affiliation: *Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, and Institute of Medical and Biomedical Education, St. George's, University of London, London, United Kingdom; and Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
authors.forename: Francesc
authors.initials: F
authors.lastname: Miralles
authors.affiliation: *Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, and Institute of Medical and Biomedical Education, St. George's, University of London, London, United Kingdom; and Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
authors.forename: Lutz
authors.initials: L
authors.lastname: Birnbaumer
authors.affiliation: *Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, and Institute of Medical and Biomedical Education, St. George's, University of London, London, United Kingdom; and Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Large
authors.affiliation: *Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, and Institute of Medical and Biomedical Education, St. George's, University of London, London, United Kingdom; and Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Albert
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D054799:Phospholipase C beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D046912:Multiprotein Complexes; D050052:TRPC Cation Channels; D011493:Protein Kinase C; D054799:Phospholipase C beta; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: Ca2+ signaling; PLC activity; electrophysiology; phosphoinositol signaling