Differentiation method-dependent expression of leptin in adipocyte cell lines

Leptin, the product of the ob gene, is expressed exclusively in adipose tissue, However, adipocyte cell lines, such as 3T3-L1 adipocytes, have generally been reported to express extremely low levels of leptin mRNA. We compared 3T3-L1's to the closely related Line 3T3-F442A, and to another murine adipocyte line, TA1. TA1 cells, when differentiated by indomethacin/insulin treatment, express leptin at levels greater than those of 3T3-L1 adipocytes differentiated by the traditional methylisobutylxanthine/dexamethasone/insulin protocol. How ever, when 3T3-L1's are differentiated in the presence of indomethacin/insulin their expression levels of leptin increase dramatically. 3T3-F442A preadipocytes also express high levels of leptin when differentiated in the presence of T-3 and insulin, but when differentiated in the presence of indomethacin/insulin, expression levels drop precipitously. These changes in leptin mRNA and protein expression are not reflected by changes in CCAAT/enhancer binding protein-alpha (c/EBP alpha), peroxizomal proliferator activated receptor-gamma CPPAHy), lipoprotein lipase (LPL), fatty-acid binding protein aP2 or uncoupling protein-2 (UCP2) mRNA levels, and suggest a mechanism unique to the leptin gene. (C) 1998 Academic Press.