Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
PLoS One. 2012;7(9):e45056. doi: 10.1371/journal.pone.0045056. Epub 2012 Sep 11.
It is suggested that migration of airway smooth muscle (ASM) cells plays an important role in the pathogenesis of airway remodeling in asthma. Increases in intracellular Ca(2+) concentrations (Ca(2+)) regulate most ASM cell functions related to asthma, such as contraction and proliferation. Recently, STIM1 was identified as a sarcoplasmic reticulum (SR) Ca(2+) sensor that activates Orai1, the Ca(2+) channel responsible for store-operated Ca(2+) entry (SOCE). We investigated the role of STIM1 in Ca(2+) and cell migration induced by platelet-derived growth factor (PDGF)-BB in human ASM cells. Cell migration was assessed by a chemotaxis chamber assay. Human ASM cells express STIM1, STIM2, and Orai1 mRNAs. SOCE activated by thapsigargin, an inhibitor of SR Ca(2+)-ATPase, was significantly blocked by STIM1 siRNA and Orai1 siRNA but not by STIM2 siRNA. PDGF-BB induced a transient increase in Ca(2+) followed by sustained Ca(2+) elevation. Sustained increases in Ca(2+) due to PDGF-BB were significantly inhibited by a Ca(2+) chelating agent EGTA or by siRNA for STIM1 or Orai1. The numbers of migrating cells were significantly increased by PDGF-BB treatment for 6 h. Knockdown of STIM1 and Orai1 by siRNA transfection inhibited PDGF-induced cell migration. Similarly, EGTA significantly inhibited PDGF-induced cell migration. In contrast, transfection with siRNA for STIM2 did not inhibit the sustained elevation of Ca(2+) or cell migration induced by PDGF-BB. These results demonstrate that STIM1 and Orai1 are essential for PDGF-induced cell migration and Ca(2+) influx in human ASM cells. STIM1 could be an important molecule responsible for airway remodeling.
有人提出，气道平滑肌（ASM）细胞的迁移在哮喘气道重塑的发病机制中起着重要作用。细胞内钙离子浓度（[Ca（2+）]（i））的增加调节与哮喘相关的大多数 ASM 细胞功能，如收缩和增殖。最近，STIM1 被鉴定为肌浆网（SR）Ca（2+）传感器，可激活 Orai1，Orai1 是负责储存操作的 Ca（2+）内流（SOCE）的 Ca（2+）通道。我们研究了 STIM1 在血小板衍生生长因子（PDGF）-BB 诱导的人 ASM 细胞 [Ca（2+）]（i）和细胞迁移中的作用。通过趋化室测定评估细胞迁移。人 ASM 细胞表达 STIM1、STIM2 和 Orai1 mRNA。STIM1 siRNA 和 Orai1 siRNA 但不是 STIM2 siRNA 显著阻断由 thapsigargin（一种肌浆网 Ca（2+）-ATPase 抑制剂）激活的 SOCE。PDGF-BB 诱导 [Ca（2+）]（i）的短暂增加，随后持续升高[Ca（2+）]（i）。PDGF-BB 引起的持续升高[Ca（2+）]（i）明显受 EGTA 螯合剂或 STIM1 或 Orai1 siRNA 抑制。PDGF-BB 处理 6 小时后，迁移细胞的数量明显增加。siRNA 转染敲低 STIM1 和 Orai1 抑制 PDGF 诱导的细胞迁移。同样，EGTA 显著抑制 PDGF 诱导的细胞迁移。相比之下，siRNA 转染 STIM2 不抑制 PDGF-BB 诱导的持续升高[Ca（2+）]（i）或细胞迁移。这些结果表明，STIM1 和 Orai1 是 PDGF 诱导的人 ASM 细胞迁移和 Ca（2+）内流所必需的。STIM1 可能是负责气道重塑的重要分子。
