Microarray analysis indicates that vitamin A alters expression profiles of bovine intramuscular preadipocytes during adipogenesis

Beef marbling is caused by intramuscular deposition, and it is an economically important trait in the beef industry. Vitamin A (VA) is an important feed supplement for cattle, but it can hinder marbling if provided in excess. In cattle, VA forms various derivatives such as all-trans retinoic acid (ATRA) and 9-cis retinoic acid (9cRA). Therefore, we investigated the genes involved in bovine intramuscular adipogenesis after VA treatment with ATRA and 9cRA. Differential gene expression levels were validated by microarray analysis in a clonal bovine intramuscular preadipocyte (BIP) cell line derived from the intramuscular adipose tissue of Japanese Black cattle. BIP cells were harvested six days after adipogenic stimulation with either 1 μM ATRA, 1 μM 9cRA, or nonretinoic acids control. The ATRA- and 9cRA-treated cells exhibited reduced transcription of genes involved in the circulatory system and muscle development compared with the no retinoic acid (RA) treatment. In addition, the ATRA- and 9cRA-treated cells exhibited increased transcription of genes involved in the immune system, protein kinase B signaling, and responses to various stimuli. These results demonstrate the lower expression of muscle development in ATRA- and 9cRA-treated BIP cells during adipogenesis. BIP cells were cultured according to previously reported methods (Aso et al. 1995, Mizoguchi et al. 2014). Confluent cultures were transferred to fresh Dulbecco’s modified Eagle’s medium, which contained 50 ng/mL insulin, 0.25 μM dexamethasone, 5 mM octanoate, 10 mM acetic acid, 10% fetal bovine serum, 100 U/mL penicillin, and 100 μg/mL streptomycin. The cells were cultured for up to 6 days and the medium was changed every 2 days. BIP cells were treated with ATRA (1 μM), 9cRA (1 μM), or they received no treatment (control).