Cloning, expression analysis, and regulatory mechanisms of bovine chemerin and chemerin receptor

Recently, we reported that chemerin, a new adipokine, is highly expressed in the adipose tissue, up-regulated during adipocyte differentiation, and regulates adipogenesis via its own receptor in mice. The objectives of this study were to clone chemerin and its receptor from the adipose tissues of Japanese Black cattle and to investigate the expression of these genes in 16 different tissues. We compared the gene expression of chemerin and its receptor between adipocytes and stromal-vascular (S-V) cells (non-adipocytes) prepared from subcutaneous adipose tissue. In addition, we investigated the mRNA expression levels of chemerin and its receptor in bovine differentiated adipocytes. The DNA sequences of bovine chemerin and its receptor were determined, and they were found to be highly homologous to those of humans, mice, and pigs. The amino acid sequences predicted for the full-length cDNA of bovine chemerin and its receptor were also similar to those of humans, mice, and pigs, suggesting that these genes have similar functions. Bovine chemerin mRNA was highly expressed in the adipose and liver tissues, and the transcripts of chemerin receptor were widely expressed in several tissues including adipose, muscle, liver, and brain tissues. The expression of bovine chemerin mRNA was higher in adipocytes than in S-V cells prepared from adipose tissue. The transcripts of chemerin and its receptor were up-regulated during adipocyte differentiation. Treatment with tumor necrosis factor (TNF)-α (10 ng/mL) in bovine differentiated adipocytes increased the mRNA expression of chemerin and its receptor. These results indicate that chemerin, a new adipokine highly expressed in the adipocytes of bovine adipose tissue, is the TNF-α-up-regulated gene with a role in adipogenesis.