ESTROGEN EFFECTS ON PROTEIN EXPRESSED BY MARROW STROMAL OSTEOBLASTS

The aim of this study was to follow the changes of estrogen treatment on osteoblastic MBA-15 cells derived from marrow stromal origin. Follo wing exposure to estrogen, the cells' patterns of protein synthesis an d expression were monitored, The proteins synthesized by MBA-15 cells were identified in cell lysate fractionated to soluble proteins (SOL), cytoskeleton (CK), membrane and nuclei, and intermediate filaments (P L) fractions. These cellular fractions of the osteoblastic MBA-15 cell cultures were assayed on SDS-PAGE of total proteins or following radi olabeling of cells by [(35)-S]-Methionine, Changes in cytoskeletal and membrane proteins of the control and treated cells were monitored by these assays. Reduction in expression of tubulin (TUB) and thropomyosi n (TRI) were observed by western blot analysis and of actin by fluores cein staining. A reduction in expression of an antigen highly expresse d by osteogenic cells and detected by MoAb 85/12 was also observed in these cells. These experiments showed reduction in cytoskeletal and ot her cellular proteins in the stromal osteoblastic MBA-15 cells treated with 17 beta-Estradiol in comparison to untreated cells. (C) 1997 Aca demic Press.