Steroid effects on protein synthesis in cultured smooth muscle cells from rat aorta

To examine the direct effects of steroids on vascular smooth muscle, we have incubated rat aortic vascular smooth muscle cells in culture either steroid-free, or with natural and synthetic corticosteroids (RU26988, dexamethasone, corticosterone, 9 alpha-fluorocortisol, aldosterone, deoxycorticosterone) or sex steroids (estradiol, 5 alpha-dihydrotestosterone). At the end of 24 h, cultures were pulsed with [35S]methionine for 2 h, the cells lysed, and patterns of incorporation of isotope into protein determined by two-dimensional gel electrophoresis and autoradiography. Neither estradiol nor 5 alpha-dihydrotestosterone altered protein synthetic profiles compared with control (steroid-free) incubations. In contrast, cultures exposed to the six corticosteroids at 10(-7) M showed an identical pattern of response (6 proteins increased, 6 proteins decreased). This response appears to be glucocorticoid specific, since the mineralocorticoids (9 alpha-fluorocortisol, aldosterone, and deoxycorticosterone) did not have any effects over and above those seen with the pure glucocorticoid RU26988. We interpret these data as evidence for a putative glucocorticoid domain of at least 12 proteins in rat vascular smooth muscle cells. In contrast, there appear to be no comparable estrogen-, androgen-, or mineralocorticoid-specific changes in these cells.