REGULATION OF FAT CD36 GENE-EXPRESSION - FURTHER EVIDENCE IN SUPPORT OF A ROLE OF THE PROTEIN IN FATTY-ACID BINDING/TRANSPORT/

Much biochemical evidence has implicated rat adipocyte CD36 (FAT) in m embrane binding and transport of long-chain fatty acids (FA). Expressi on of the mRNA favored tissues with active FA metabolism and was upreg ulated in vivo with diabetes and with high fat feeding. In culture, CD 36 mRNA was a strong marker of preadipocyte differentiation and was mo dulated by the same factors effective on mRNAs coding for other protei ns involved in FA metabolism. In preadipocytes, long-chain FA or 2-bro mopalmitate but not short-chain FA strongly induced CD36 mRNA within 8 h to an optimum within 24 h. Removal of the FA resulted in a decay of CD36 mRNA with a half life of about 12 h. In differentiated adipocyte s, levels of CD36 mRNA were downregulated by the 3'. 5'-cyclic adenosi ne monophosphate, cAMP, analog, 8-(4-chlorophenylthio) adenosine, 8-CP T, at concentrations of 1-100 mu M. The effect, observed within 6 h, w as optimal after 18 h and independent of the action of 8-CPT to mobili ze FA. Regulation of CD36 expression by factors effective on expressio n of other proteins implicated in FA metabolism is consistent with its role in membrane FA transport.