mt-COX1, mt-ND1 and CREBP are indicators of intramuscular fat content in Hanwoo (Korean cattle)

We identified differentially expressed genes associated with intramuscular fat content in Hanwoo Korean cattle. Pre-screening with differential display reverse transcription polymerase chain reaction (DDRT-PCR) identified 15 differentially expressed genes (DEGs) in the muscle of 12- and 27-month-old steers. Eleven genes were validated by qRT-PCR. These 11 DEGs were mainly involved in energy metabolism or were muscle structural or ribosomal proteins. To determine whether these DEGs are associated with adipocyte development, we examined the gene expressions of the 15 genes during preadipocyte differentiation. Two genes associated with energy metabolism, mitochondrial cytochrome c oxidase 1 (mt-COX1) and NADH dehydrogenase I (mt-ND1), and one gene, cAMP response element binding protein (CREBP), showed increased gene expression during adipocyte differentiation. Finally, to determine whether the three genes are associated with intramuscular fat content, we analyzed gene expression in muscles with divergent marbling phenotypes (7.5% vs. 23.5%). The three genes (mt-COX1, mt-ND1 and CREBP) were significantly expressed in highly marbled muscle. Thus, mt-COX1, mt-ND1 and CREBP could be relevant indicators of intramuscular fat content in Hanwoo.