Overlapping but not identical protein synthetic domains in cardiovascular cells in response to glucocorticoid hormones.

We have compared, by two-dimensional gel electrophoresis, the effects of glucocorticoids on newly synthesized proteins of cultured cardiovascular cells (rat synthetic- and contractile-state vascular smooth muscle, rat cardiac muscle and non-muscle, and bovine endothelium) and rat hepatoma (H4) cells, as a non-cardiovascular target. In each cell type, glucocorticoids consistently affected a particular set of proteins termed the glucocorticoid domain for that target tissue. Cardiovascular cells exhibited overlapping but non-identical glucocorticoid domains; these domains varied in number of proteins, proportion of induced and repressed proteins, and overlap (extent of shared protein responses) between the various cardiovascular cell types studied. On physico-chemical and co-electrophoresis data the glucocorticoid domain of cardiovascular cells also overlapped with that of hepatoma cells, but to a lesser extent. The glucocorticoid domain in cardiac muscle cells included five proteins not found in cardiac non-muscle cells. Contractile-state vascular smooth muscle cells showed some, but not all, of the proteins affected by glucocorticoids in synthetic-state cells; the only response seen in the contractile but not vascular smooth muscle cells was a protein of Mr-52K and pI-5.3, which was also induced in spontaneously contractile cardiac muscle. Further characterization of contractile and synthetic vascular smooth muscle and cardiac muscle proteins affected by glucocorticoids is necessary to ascertain their role(s) in specialized cardiovascular functions.