DIFFERENTIAL EXPRESSION OF THE PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR-GAMMA (PPAR-GAMMA) AND ITS COACTIVATORS STEROID-RECEPTOR COACTIVATOR-1 AND PPAR BINDING-PROTEIN PBP IN THE BROWN FAT, URINARY-BLADDER, COLON, AND BREAST OF THE MOUSE

Peroxisome proliferator-activated receptors (PPARs) regulate genes inv olved in lipid metabolism and adipocyte differentiation. Steroid recep tor coactivator-l (SRC-1) and PPAR-binding protein (PBP) interact with PPAR gamma and act as coactivators to enhance ligand-dependent transc ription. We report here that PPAR gamma, SRC-I, and PBP are differenti ally expressed in the brown fat, transitional epithelium of the urinar y bladder, colonic mucosa, and mammary epithelium of the adult mouse, PPAR gamma and PBP are expressed in the transitional epithelium of uri nary bladder and in brown adipose tissue, but not SRC-1, in the coloni c mucosa, PPAR gamma expression occurs throughout the villi, whereas t he expression of both SRC-1 and PBP is confined mostly to the crypts. The expression of both SRC-1 and PBP is prominent in the breast epithe lium of nonpregnant, pregnant, and lactating mice, whereas PPAR gamma expression appeared prominent during lactation, During early embryonic development, PPAR gamma, SRC-1, and PBP are differentially expressed, with only Limited cell types displaying overlapping expression. PPAR gamma and PBP expression overlapped in the brown fat and urogenital si nus at stage E15.5 of embryogenesis, whereas SRC-1 expression occurred mostly in neuroepithelium and cartilage between stages E9.5 and E13.5 of embryogenesis.