Comparison of Metabolic Network Between Muscle and Intramuscular Adipose Tissues in Hanwoo Beef Cattle Using a Systems Biology Approach

The interrelationship between muscle and adipose tissues plays a major role in determining the quality of carcass traits. The objective of this study was to compare metabolic differences between muscle and IMA tissues in the longissimus dorsi (LD) of Hanwoo (Bos Taurus coreanae) using the RNA-seq technology and a systems biology approach. The LD section between the 6th to 7th ribs were removed from nine (each of three cows, steers and bulls) Hanwoo (carcass weight of 430.2±40.66 kg) immediately after slaughter. The total mRNA from muscle, IMA, subcutaneous adipose and omental adipose tissues were isolated and sequenced. The reads passed quality control were mapped onto the bovine reference genome (build bosTau6), and differentially expressed genes across tissues were identified. The KEGG pathway enrichment tests revealed the opposite direction of metabolic regulation between muscle and IMA. Metabolic gene network analysis clearly indicated that oxidative metabolism were up-regulated in muscle while down-regulated in IMA. Interestingly, pathways for regulating cell adhesion, structure and integrity and chemokine signaling pathway were up-regulated in IMA while down-regulated in muscle. It is thus inferred that IMA may play an important role in the regulation of development and structure of the LD tissues and muscle/adipose communication.