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  • STIM-1 and ORAI-1 channel mediate angiotensin-II-induced expression of Egr-1 in vascular smooth muscle cells.

STIM-1 and ORAI-1 channel mediate angiotensin-II-induced expression of Egr-1 in vascular smooth muscle cells.

Journal of cellular physiology (2017-01-21)
Estelle R Simo-Cheyou, Ju Jing Tan, Ryszard Grygorczyk, Ashok K Srivastava
ABSTRACT

An upregulation of Egr-1 expression has been reported in models of atherosclerosis and intimal hyperplasia and, various vasoactive peptides and growth promoting stimuli have been shown to induce the expression of Egr-1 in vascular smooth muscle cells (VSMC). Angiotensin-II (Ang-II) is a key vasoactive peptide that has been implicated in the pathogenesis of vascular diseases. Ang-II elevates intracellular Ca2+ through activation of the store-operated calcium entry (SOCE) involving an inositol-3-phosphate receptor (IP3R)-coupled depletion of endoplasmic reticular Ca2+ and a subsequent activation of the stromal interaction molecule 1 (STIM-1)/Orai-1 complex. However, the involvement of IP3R/STIM-1/Orai-1-Ca2+ -dependent signaling in Egr-1 expression in VSMC remains unexplored. Therefore, in the present studies, we have examined the role of Ca2+ signaling in Ang-II-induced Egr-1 expression in VSMC and investigated the contribution of STIM-1 or Orai-1 in mediating this response. 2-aminoethoxydiphenyl borate (2-APB), a dual non-competitive antagonist of IP3R and inhibitor of SOCE, decreased Ang-II-induced Ca2+ release and attenuated Ang-II-induced enhanced expression of Egr-1 protein and mRNA levels. Egr-1 upregulation was also suppressed following blockade of calmodulin and CaMKII. Furthermore, RNA interference-mediated depletion of STIM-1 or Orai-1 attenuated Ang-II-induced Egr-1 expression as well as Ang-II-induced phosphorylation of ERK1/2 and CREB. In addition, siRNA-induced silencing of CREB resulted in a reduction in the expression of Egr-1 stimulated by Ang-II. In summary, our data demonstrate that Ang-II-induced Egr-1 expression is mediated by STIM-1/Orai-1/Ca2+ -dependent signaling pathways in A-10 VSMC.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
KN-93, ≥98% (HPLC)
Sigma-Aldrich
W-7, Hydrochloride, A cell-permeable and reversible calmodulin antagonist that inhibits myosin light chain kinase (IC₅₀ = 51 µM) and Ca2+-calmodulin-dependent phosphodiesterase (IC₅₀ = 28 µM).
Sigma-Aldrich
Anti-STIM1 antibody produced in rabbit, affinity isolated antibody, buffered aqueous solution
Sigma-Aldrich
2-Aminoethyl diphenylborinate, 97%
Sigma-Aldrich
KN-92, KN-92, CAS 1135280-28-2, is useful as a negative control for KN-93 (Cat. No. 422708), a Ca2+/CaM Kinase II inhibitor.