DIFFERENTIATION-DEPENDENT EXPRESSION OF OBESE (OB) GENE BY PREADIPOCYTES AND ADIPOCYTES IN PRIMARY CULTURES OF PORCINE STROMAL-VASCULAR CELLS

The relationship between obese (ob) gene expression and preadipocyte d ifferentiation was examined in primary cultures es of porcine stromal- vascular (S-V) cells by Northern-blot analysis using a pig ob cDNA pro be, Isolated adipocytes expressed high levels of ob gene, but S-V cell s did not express the ob gene, Cultures were seeded with fetal bovine serum (FBS) plus dexamethasone (Dex) for 3 days followed by ITS (insul in 5 mu g/ml, transferrin 5 mu g/ml, and selenium 5 ng/ml) treatment f or 6 days. Detectable levels of ob mRNA first appeared at day 1 with v ery low activity of glycerol phosphate dehydrogenase (GPDH). Levels of ob mRNA increased in parallel with preadipocyte number or GPDH activi ty at the later times in cultures. The depletion of preadipocytes by c omplement-mediated cytotoxicity at day 3 of culture resulted in marked ly decreased ob mRNA expression. Immunocytochemical analysis showed th at ob protein was localized in the cytosol of preadipocytes and adipoc ytes. These data indicated that the ob gene is expressed by preadipocy tes and ob gene expression may be correlated with preadipocyte recruit ment as well as fat cell size. (C) 1997 Elsevier Science B.V.