Regulation of expression of the mouse adiponectin gene by the C/EBP family via a novel enhancer region

Adiponectin plays protective roles against the development of insulin resistance and atherosclerosis. To clarify the regulation of adiponectin gene expression, reporter gene assay by using the several truncated mouse adiponectin 5′-flanking regions was performed after the differentiation of 3T3-L1 preadipocytes. The results indicated that a novel mouse adiponectin enhancer exists in the− 2228 to − 2066 region. Nuclear proteins from the differentiated adipocytes bound to two DNA fragments, namely, − 2153 to − 2114 and − 2093 to − 2054. Both fragments had a common motif, CACAATGC, which was similar to the CCAAT/enhancer binding protein (C/EBP) binding motif. A gel mobility shift assay with anti-C/EBPs antibodies showed that C/EBP α, β, and δ bound to this motif. These data provide the first evidence that the transcriptional activity of the mouse adiponectin gene during adipocyte differentiation is enhanced by the motif in a novel adiponectin enhancer region, via the recruitment of the C/EBPs.