G protein-coupled estrogen receptor1 (GPER1) may mediate Rho-kinase (ROCK-2) up-regulation in coronary endothelial cells

Objective: Effect of estrogenic compounds and 17β-estradiol (E2), which induces endothelial cell motility, was investigated on ROCK-2 expression in rat coronary vascular endothelial cells (CVEC).

Methods: The CVEC were isolated from the heart of Wistar rats by collagenase (0.04%) and incubated with E2 (1-100 nM), Estrogen receptor α (ERα) agonist: propyl pyrazole triol (PPT, 10 nM); ERβ agonists: (2,3-bis(4-hydroxyphenyl)-propionitrile, DPN, 10 nM) and E2-conjugate with bovine serum albumin (E2-BSA, 1 nM); and GPER1 agonist: G1 (100 nM). Furthermore, the effect of combination of E2 with estrogen receptors (ERs) antagonist and GPER1 agonist, ICI-182780 (10 µM), physiological estrogen antagonists: progesterone (P4, 10-100 nM) and testosterone (T, 10-100 nM); transcription inhibitor: actinomycin-D (1 µg/ml); GPER1 antagonist: G-15 (100 nM), superoxide dismutase, (SOD, 500 U/ml); Gi/o protein inhibitor: pertussis toxin (PTX, 100 µg/ml); and epidermal growth factor receptor (EGFR) blocker: AG-1478 (10 µM) was tested. After 24h incubation, ROCK-2 and GPER1 protein expressions were detected in the CVEC by Western-blotting.

Results: E2, ICI-182780, and G1 but not E2-BSA significantly up-regulated ROCK-2 expression, which was suppressed by actinomycin-D, PTX, AG-1478, and G-15. However, PPT and DPN had no effects on the ROCK-2 expression. ICI-182780, P4, T or SOD did not antagonize the E2 action. GPER1 expression was demonstrated in the CVEC.

Conclusions: Estrogens could up-regulate ROCK-2 in the rat CVEC through GPER1 and EGFR transactivation.