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Article10.1096/fasebj.22.1_supplement.1213.3

STIM1 regulates store operated calcium entry (SOCE) in human airway smooth muscle

Michael A Thompson,David Zhang,Gary C. Sieck,Christina M. Pabelick,Y. S. Prakash-2008-03-01-The FASEB Journal
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TL;DRAbstract

Intracellular Ca 2+ regulation in human airway smooth muscle (hASM) involves plasma membrane (PM) Ca 2+ influx, including that triggered by sarcoplasmic reticulum (SR) Ca 2+ depletion, i.e. store‐operated Ca 2+ entry (SOCE). While transient receptor potential channels (e.g. TRPC3, TRPC4) are thought to mediate SOCE, the mechanisms triggering or regulating SOCE are being actively investigated. Recent studies suggest that stromal interaction molecule 1 (STIM1) acts as a signaling mediator between PM and SR, potentially regulating Ca 2+ entry via SOCE. In hASM, fluorescence microscopy and western blot analyses were used to verify the presence of STIM1. SR Ca 2+ depletion with 10μM cyclopiazonic acid (CPA) resulted in increased STIM1 expression in the PM fraction, compared to controls. Transfection with 50nM STIM1 siRNA for 48h significantly decreased STIM1 levels. In cells where [Ca 2+ ] i was measured using fura 2‐AM, SOCE was significantly reduced in cells transfected with STIM1 siRNA.

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Intracellular Ca 2+ regulation in human airway smooth muscle (hASM) involves plasma membrane (PM) Ca 2+ influx, including that triggered by sarcoplasmic reticulum (SR) Ca 2+ depletion, i.e. store‐operated Ca 2+ entry (SOCE). While transient receptor potential channels (e.g. TRPC3, TRPC4) are thought to mediate SOCE, the mechanisms triggering or regulating SOCE are being actively investigated. Recent studies suggest that stromal interaction molecule 1 (STIM1) acts as a signaling mediator between PM and SR, potentially regulating Ca 2+ entry via SOCE. In hASM, fluorescence microscopy and western blot analyses were used to verify the presence of STIM1. SR Ca 2+ depletion with 10μM cyclopiazonic acid (CPA) resulted in increased STIM1 expression in the PM fraction, compared to controls. Transfection with 50nM STIM1 siRNA for 48h significantly decreased STIM1 levels. In cells where [Ca 2+ ] i was measured using fura 2‐AM, SOCE was significantly reduced in cells transfected with STIM1 siRNA.

Keywords

STIM1TRPC3Cyclopiazonic acidTRPCORAI1Cell biologyEndoplasmic reticulumTransfection

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