Caveolin-1 alters Ca2+ signal duration through specific interaction with the Gαq family of G proteins

Parijat Sengupta, Finly Philip, Suzanne Scarlata

Research output: Contribution to journalArticle

Abstract

Caveolae are membrane domains having caveolin-1 (Cav1) as their main structural component. Here, we determined whether Cav1 affects Ca2+ signaling through the Gα q-phospholipase-Cβ (PLCβ) pathway using Fischer rat thyroid cells that lack Cav1 (FRTcav-) and a sister line that forms caveolae-like domains due to stable transfection with Cav1 (FRTcav+). In the resting state, we found that eCFP-Gβγ and Gαq-eYFP are similarly associated in both cell lines by Forster resonance energy transfer (FRET). Upon stimulation, the amount of FRET between Gα q-eYFP and eCFP-Gβγ remains high in FRTcav- cells, but decreases almost completely in FRTcav+ cells, suggesting that Cav1 is increasing the separation between Gαq-Gβγ subunits. In FRTcav- cells overexpressing PLCβ, a rapid recovery of Ca2+ is observed after stimulation. However, FRTcav+ cells show a sustained level of elevated Ca2+. FRET and colocalization show specific interactions between Gαq and Cav1 that increase upon stimulation. Fluorescence correlation spectroscopy studies show that the mobility of Gαq-eGFP is unaffected by activation in either cell type. The mobility of eGFP-Gβγ remains slow in FRTcav- cells but increases in FRTcav+ cells. Together, our data suggest that, upon stimulation, Gα q(GTP) switches from having strong interactions with Gβγ to Cav1, thereby releasing Gβγ. This prolongs the recombination time for the heterotrimer, thus causing a sustained Ca2+ signal.

Original languageEnglish (US)
Pages (from-to)1363-1372
Number of pages10
JournalJournal of cell science
Volume121
Issue number9
DOIs
StatePublished - May 1 2008

Keywords

  • Ca signaling
  • Caveolin-1
  • G proteins
  • Phospholipase C

ASJC Scopus subject areas

  • Cell Biology

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