Differential Expressions of G0/G1 Switch Gene 2 and Comparative Gene Identification-58 are Associated with Fat Content in Bovine Muscle

Regulation of lipolysis in muscle is a potential mechanism affecting marbling in beef carcasses and fat accumulation in muscles of humans, which is a known risk factor for type 2 diabetes. Adipose triglyceride lipase-mediated lipolysis is inhibited by G0/G1 switch gene 2 (G0S2) and co-activated by comparative gene identification-58 (CGI-58). In this study, bovine G0S2 and CGI-58 were sequenced, and expressions of these genes were compared among various tissues and in muscles between bulls and steers with different degrees of marbling. The protein coding sequences of bovine G0S2 and CGI-58 revealed breed-specific SNPs, causing two amino acid variations for each protein. Bovine CGI-58 mRNA showed two isoforms from alternative splicing. The G0S2 gene was preferentially expressed in fat and, to a lesser degree, in the liver; whereas, CGI-58 was highly expressed in the muscle and fat (P < 0.05), suggesting their association with lipid metabolism in those tissues. The longissimus dorsi muscle (LM) of steers showed higher FABP4, G0S2 and CGI-58 mRNA expression levels than the LM of bulls, implying the roles of those genes more in marbling of steers than in that of bulls. The G0S2 expression was markedly higher in the intramuscular fat (IMF) (P < 0.001); whereas, the CGI-58 expression was significantly higher in the pure muscle portion of the LM of steers (P < 0.01), suggesting that G0S2 and CGI-58 may regulate IMF and intramyocellular triglycerides, respectively. Taken together, our data suggest that G0S2 and CGI-58 are associated with fat content in bovine species.