STIM1 Regulates Platelet-Derived Growth Factor-Induced Migration and Ca2+ Influx in Human Airway Smooth Muscle Cells

Nobukazu Suganuma,Yoshinori Hasegawa,Satoru Ito,Hiromichi Aso,Masahiro Sokabe,Masashi Kondo,Mitsuo Sato,Ladzlo Csernoch

doi:10.1371/journal.pone.0045056

Nobukazu Suganuma, Yoshinori Hasegawa + Show 6 more

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https://doi.org/10.1371/journal.pone.0045056

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Journal: PloS one	Publication Date: Sep 11, 2012
Citations: 79	License type: CC BY 4.0

Affiliation: Nagoya University

Abstract

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 Ca2+ concentrations ([Ca2+]i) regulate most ASM cell functions related to asthma, such as contraction and proliferation. Recently, STIM1 was identified as a sarcoplasmic reticulum (SR) Ca2+ sensor that activates Orai1, the Ca2+ channel responsible for store-operated Ca2+ entry (SOCE). We investigated the role of STIM1 in [Ca2+]i 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 Ca2+-ATPase, was significantly blocked by STIM1 siRNA and Orai1 siRNA but not by STIM2 siRNA. PDGF-BB induced a transient increase in [Ca2+]i followed by sustained [Ca2+]i elevation. Sustained increases in [Ca2+]i due to PDGF-BB were significantly inhibited by a Ca2+ 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 [Ca2+]i or cell migration induced by PDGF-BB. These results demonstrate that STIM1 and Orai1 are essential for PDGF-induced cell migration and Ca2+ influx in human ASM cells. STIM1 could be an important molecule responsible for airway remodeling.

Highlights

Airway remodeling due to repeated airway wall damage and repair plays an important role in the pathophysiology of severe asthma [1]
Real-time quantitative Polymerase chain reaction (PCR) data showed that transfection of siRNA transfection targeting STIM1 (siSTIM1), siSTIM2, and siOrai1 induced a large decrease in mRNA levels of target genes without altering mRNA levels of non-target genes (Figure 1B)
Stromal interaction molecule 1 (STIM1) protein expression as assessed by the STIM1/actin ratio was significantly lower in the cells transfected with siSTIM1 than the control cells transfected with scrambled short interfering RNAs (siRNA) (n = 3, P,0.001) (Figure 1C)

Summary

Introduction

Airway remodeling due to repeated airway wall damage and repair plays an important role in the pathophysiology of severe asthma [1]. Accumulating evidence suggests that ASM cell migration toward the airway epithelium in response to inflammatory mediators such as platelet-derived growth factor (PDGF) contributes to the airway remodeling [2,3,4,5,6,7,8,9]. Intracellular free Ca2+ is a second messenger for ASM cell functions related to asthma, such as contraction, proliferation, and cytokine production [11,12,13,14]. SOCE closely links to the contraction and cell proliferation of ASM cells [11,14,19,20,21]. Peel et al have demonstrated that SOCE is mediated by STIM1 and Orai in human ASM cells [27,28]

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