Functional role of stromal interaction molecule 1 (STIM1) in vascular smooth muscle cells

Knockdown of stromal interaction molecule 1 attenuates store-operated Ca2+ entry and Ca2+ responses to acute hypoxia in pulmonary arterial smooth muscle

“…5). These results are consistent with findings in human airway and coronary arterial smooth muscle (36,51) and suggest that STIM2 did not contribute to activation of SOC by CPA; however, this possibility is not supported by the Mn 2ϩ quenching data (Fig. 6 (Fig.…”

“…The function of STIM2 is not as well understood as that of STIM1. Some studies indicate that STIM2 has little or no effect on SOCE (22,30,36,51), whereas others suggest that STIM2 may inhibit STIM1 (50), act to maintain basal cytoplasmic and SR/ER luminal Ca 2ϩ (4), or regulate store-dependent and -independent activation of SOC (35). Although STIM2 was detected in airway and coronary arterial smooth muscle (36, 51), expression in PASMC has not been reported.…”

“…Which of these possibilities is correct remains controversial. Recent studies in a wide variety of cell types, including smooth muscle (8,18,36,51), have shown that SOCE requires a 90-kDa transmembrane Ca 2ϩ -binding protein known as stromal interaction molecule 1 (STIM1) (9,13,17,42). STIM1 is found in sarco(endo)plasmic reticulum (SR/ER) and plasma membrane and functions as both the sensor of Ca 2ϩ within the SR/ER lumen and the transducer of SOC activation in response to SR/ER Ca 2ϩ depletion.…”

Orai1 interacts with STIM1 and mediates capacitative Ca2+ entry in mouse pulmonary arterial smooth muscle cells

“…To date, there is very little evidence for the roles of Orai1 and STIM1 in vascular smooth muscle cells. STIM1 was shown to express in cultured coronary artery smooth muscle cells (47), saphenous vein cells (18), mesenteric artery smooth muscle cells (5), aorta smooth muscle cells (5,7,37), and PASMCs (24,32). siRNA targeting STIM1 resulted in reduction of Ca 2ϩ entry and whole cell current activated by CPA or thapsigargin (18,25,32,37,47).…”

STIM1/Orai1-mediated store-operated Ca2+ entry: the tip of the iceberg

“…It was shown that Orai1 without its N-terminal tail displayed a small effect on SOCE. In addition, the N-terminus region of Orai1 was important for poreformation of the channel (27). Furthermore, the C-terminus region appears to be a key element for communication between Orai1, but not Orai2 or Orai3, and STIM1 (28).…”