TRPC1 and STIM1 mediate capacitative Ca2+ entry in mouse pulmonary arterial smooth muscle cells
AUTOR(ES)
Ng, Lih Chyuan
FONTE
Blackwell Science Inc
RESUMO
Previous studies in pulmonary arterial smooth muscle cells (PASMCs) showed that the TRPC1 channel mediates capacitative Ca2+ entry (CCE), but the molecular signal(s) that activate TRPC1 in PASMCs remains unknown. The aim of the present study was to determine if TRPC1 mediates CCE through activation of STIM1 protein in mouse PASMCs. In primary cultured mouse PASMCs loaded with fura-2, cyclopiazonic acid (CPA) caused a transient followed by a sustained rise in intracellular Ca2+ concentration ([Ca2+]i). The transient but not the sustained rise in [Ca2+]i was partially inhibited by nifedipine. In addition, CPA increased the rate of Mn2+ quench of fura-2 fluorescence that was inhibited by SKF 96365, Ni2+, La3+ and Gd3+, exhibiting pharmacological properties characteristic of CCE. The nifedipine-insensitive sustained rise in [Ca2+]i and the increase in Mn2+ quench of fura-2 fluorescence caused by CPA were both inhibited in cells pretreated with antibody raised against an extracellular epitope of TRPC1. Moreover, STIM1 siRNA reduced the rise in [Ca2+]i and Mn2+ quench of fura-2 fluorescence caused by CPA, whereas overexpression of STIM1 resulted in a marked increase in these responses. RT-PCR revealed TRPC1 and STIM1 mRNAs, and Western blot analysis identified TRPC1 and STIM1 proteins in mouse PASMCs. Furthermore, TRPC1 was found to co-immunoprecipitate with STIM1, and the precipitation level of TRPC1 was increased in cells subjected to store depletion. Taken together, store depletion causes activation of voltage-operated Ca2+ entry and CCE. These data provide direct evidence that CCE is mediated by TRPC1 channel through activation of STIM1 in mouse PASMCs.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2714011Documentos Relacionados
- Knockdown of stromal interaction molecule 1 attenuates store-operated Ca2+ entry and Ca2+ responses to acute hypoxia in pulmonary arterial smooth muscle
- Delayed autoregulation of the Ca2+ signals resulting from capacitative Ca2+ entry in bovine pulmonary artery endothelial cells.
- ASIC1 contributes to pulmonary vascular smooth muscle store-operated Ca2+ entry
- Activation of TRPC1 by STIM1 in ER-PM microdomains involves release of the channel from its scaffold caveolin-1
- TRPC channels function independently of STIM1 and Orai1