Differential expression of the peripheral benzodiazepine receptor and gremlin during adipogenesis

This study used the mRNA differential display technique to identify differentially expressed genes during the process of adipogenesis in the preadipocyte cell line, 3T3-L1. 3T3-L1 cells were treated with dexamethasone, isobutyl-1-methyl-xanthine, and insulin to induce differentiation into mature adipocytes. Cells were collected at three time-points during differentiation: Day 0 (d0), or nondifferentiated; Day 3 (d3), during differentiation; and Day 10 (d10), >90% of the cells had differentiated into mature adipocytes. Initial studies yielded 18 potentially differentially regulated cDNA candidates (8 down-regulated and 10 up-regulated). Reverse Northern and Northern blots confirmed differential expression of six of the candidates. Four of the candidates upregulated on d3 and d10 were identified by sequence analysis to be lipoprotein lipase, a well-known marker of adipocyte differentiation. A fifth candidate that was expressed in d0, but not d3 or d10, was identified as DRM/ gremlin, a bone morphogenetic protein antagonist. Finally, a sixth candidate that was increased at d3 and d10 was identified as the peripheral benzodiazepine receptor, which has been implicated in proliferation, differentiation, and cholesterol transport in cells. This study is the first to show that peripheral benzodiazepine receptor and DRM/gremlin are expressed in preadipocyte cell lines and that they are differentially regulated during adipogenesis.