Microarray Analysis Indicates That Vitamin A Alters Expression Profiles of Bovine Intramuscular Preadipocytes during Adipogenesis

Beef marbling that is caused by intramuscular deposition, is an economically important trait in the beef industry. Vitamin A (VA) is an important feed supplement for cattle, but in excess it could hinder marbling. In cattle, VA forms various derivatives such as all-trans retinoic acid (all-trans RA) and 9-cis retinoic acid (9-cis RA). So, in this study, we investigated the genes involved in bovine intramuscular adipogenesis after VA treatment with all-trans retinoic acid (all-trans RA) and 9-cis retinoic acid (9-cis RA). Differential gene expression levels were validated by microarray analysis in a clonal bovine intramuscular preadipocyte (BIP) cell line, which was derived from the intramuscular adipose tissue of the musculus longissimus thoraicis of Japanese Black cattle. The BIP cells were harvested six days after adipogenic stimulation with 1μM all-trans RA or 1μM 9-cis RA (and controls with no RA). The all-trans RA and 9-cis RA groups had reduced transcription of genes involved in the circulatory system (blood vessel development, GO:0001568) and muscle development (striated muscle tissue development, GO:0014706) compared with the non-RA treatment. Furthermore, the all-trans RA and 9-cis RA groups also had increased transcription of genes involved in immune system (immune system process, GO:0002376), protein kinase B signaling (positive regulation of protein kinase B signaling cascade, GO:0051897) and stimulus (response to stimulus, GO:0050896, GO:0051869). Therefore, the major finding of this study was a lower expression of muscle development in all-trans RA and 9-cis RA during adipogenesis in BIP.