Differential regulation of Ca2+ release-activated Ca2+ influx by heterotrimeric G proteins

Xin Xu, Kenichiro Kitamura, Kim S. Lau, Shmuel Muallem, R. Tyler Miller

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The least understood aspect of the agonist.induced Ca2+ signal is the activation and regulation of the Ca2+ release-activated Ca2+ influx (CRAC) across the plasma membrane. To explore the possible role of heterotrimeric G proteins in the various regulatory mechanisms of CRAC, continuous renal epithelial cell lines stably expressing α13 and the constitutively active α(qQ209L) were isolated and used to measure CRAC activity by the Mn2+ quench technique. Release of intracellular Ca2+ by agonist stimulation or thapsigargin was required for activation of CRAC in all cells. Although the size of the internal stores was similar in all cells, CRAC was 2-3, fold higher in α13- and α(qQ209L) -expressing cells. However, the channel was differentially regulated in the two cell types. Incubation at low [Ca2+](i), inhibition of the NOS pathway, or inhibition of tyrosine kinases inhibited CRAC activity in α13 but not α(qQ2O9L) cells. Treatment with okadaic acid prevented inhibition of the channel by low [Ca2+](i) and the protein kinase inhibitors in α13 cells. These results suggest that expression of α(qQ2O9L) dominantly activates CRAC by stabilizing a phosphorylated state, whereas expression of α13 makes CRAC activation completely dependent on phosphorylation by several kinases. G proteins may also modulate CRAC activity independently of the phosphorylation/dephosphorylation state of the pathway to increase maximal CRAC activity. Furthermore, our results suggest a general mechanism for regulation of CRAC that depends on coupling of receptors to specific G proteins.

Original languageEnglish (US)
Pages (from-to)29169-29175
Number of pages7
JournalJournal of Biological Chemistry
Volume270
Issue number49
DOIs
StatePublished - Jan 1 1995

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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