title: Phospholipase Cbeta1b associates with a Shank3 complex at the cardiac sarcolemma.
abstract: Activation of the heterotrimeric G protein Gq causes cardiomyocyte hypertrophy in vivo and in cell models. Our previous studies have shown that responses to activated Gq in cardiomyocytes are mediated exclusively by phospholipase Cβ1b (PLCβ1b), because only this PLCβ subtype localizes at the cardiac sarcolemma. In the current study, we investigated the proteins involved in targeting PLCβ1b to the sarcolemma in neonatal rat cardiomyocytes. PLCβ1b, but not PLCβ1a, coimmunoprecipitated with the high-MW scaffolding protein SH3 and ankyrin repeat protein 3 (Shank3), as well as the known Shank3-interacting protein α-fodrin. The 32-aa splice-variant-specific C-terminal tail of PLCβ1b also associated with Shank3 and α-fodrin, indicating that PLCβ1b binds via the C-terminal sequence. Shank3 colocalized with PLCβ1b at the sarcolemma, and both proteins were enriched in the light membrane fractions. Knockdown of Shank3 using siRNA reduced PLC activation and downstream hypertrophic responses, demonstrating the importance of sarcolemmal localization for PLC signaling. These data indicate that PLCβ1b associates with a Shank3 complex at the cardiac sarcolemma via its splice-variant-specific C-terminal tail. Sarcolemmmal localization is central to PLC activation and subsequent downstream signaling following Gq-coupled receptor activation.
authors.affiliation: Baker International Diabetes Institute, 75 Commercial Road, Melbourne, 3004, VIC, Australia.
authors.forename: David R
authors.initials: DR
authors.lastname: Grubb
authors.forename: Peter
authors.initials: P
authors.lastname: Iliades
authors.forename: Nicola
authors.initials: N
authors.lastname: Cooley
authors.forename: Yen Lin
authors.initials: YL
authors.lastname: Yu
authors.forename: Jieting
authors.initials: J
authors.lastname: Luo
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Filtz
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Woodcock
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D006332:Cardiomegaly / Q000378:metabolism; D002316:Cardiotonic Agents / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D009419:Nerve Tissue Proteins; D010656:Phenylephrine / Q000494:pharmacology; D054799:Phospholipase C beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D012508:Sarcolemma / Q000201:enzymology*; D015398:Signal Transduction / Q000502:physiology; D018909:src Homology Domains / Q000502:physiology; D013049:Spectrin
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002316:Cardiotonic Agents; D002352:Carrier Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D010656:Phenylephrine; D054799:Phospholipase C beta; D034741:RNA, Small Interfering; D013049:Spectrin; C120532:Shank3 protein, rat; C518035:Plcb1 protein, rat