STIM1, but not STIM2, is required for proper agonist-induced Ca2+ signaling

Jean Paul Decuypere, Giovanni Monaco, Santeri Kiviluoto, Masatsugu Oh-hora, Tomas Luyten, Humbert De Smedt, Jan B. Parys, Ludwig Missiaen, Geert Bultynck

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

The stromal interaction molecules STIM1 and STIM2 sense a decreasing Ca2+ concentration in the lumen of the endoplasmic reticulum and activate Ca2+ channels in the plasma membrane. In addition, at least 2 reports suggested that STIM1 may also interact with the inositol 1,4,5-trisphosphate (IP3) receptor. Using embryonic fibroblasts from Stim1-/-, Stim2-/- and wild-type mice, we now tested the hypothesis that STIM1 and STIM2 would also regulate the IP3 receptor. We investigated whether STIM1 or STIM2 would be the luminal Ca2+ sensor that controls the loading dependence of the IP3-induced Ca2+ release. Partial emptying of the stores in plasma-membrane permeabilized cells resulted in an increased EC50 and a decreased Hill coefficient for IP3-induced Ca2+ release. This effect occurred both in the presence and absence of STIM proteins, indicating that these proteins were not the luminal Ca2+ sensor for the IP3 receptor. Although Stim1-/- cells displayed a normal IP3-receptor function, agonist-induced Ca2+ release was reduced. This finding suggests that the presence of STIM1 is required for proper agonist-induced Ca2+ signaling. Our data do not provide experimental evidence for the suggestion that STIM proteins would directly control the function of the IP3 receptor.

Original languageEnglish
Pages (from-to)161-167
Number of pages7
JournalCell Calcium
Volume48
Issue number2-3
DOIs
Publication statusPublished - Aug 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Molecular Biology
  • Cell Biology

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