Beta-carotene acts as a regulator of skeletal muscle cells

The enzyme beta, beta-carotene-15,15'-monooxygenase (BCMO1) cleaves provitamin A carotenoids into active vitamin A principally in liver and intestine. The BCMO1 gene is expressed at low level in the muscle tissue but little is known about its function. In the chicken muscle, we observed that various BCMO1 expression levels are associated with different carotenoids contents. To investigate the potential role of BCMO1 on skeletal muscle, we assessed the impact of beta-carotene (BC, the prototype substrate of the BCMO1 enzyme) supplementation in vitro on proliferative avian myoblasts. Proliferation was evaluated by BrdU incorporation and by flow cytometry. The BrdU incorporation index was reduced and th e proportion of G0/G1 cells increased following BC supplementation. Cell differentiation was evaluated by immunolabelling of sarcomeric myosin heavy chain (MHC). In this proliferative environment, the proportion of MHC positive cells increased following BC supplementation. The effects of BC were inhibited in the presence of DEAB, an inhibitor of retinaldehyde dehydrogenase, supporting the hypothesis that the BCMO1 enzyme is active in myoblasts and can contribute to retinoic acid production from BC. Our data suggest that provitamin A carotenoids could be used as nutritional regulators of skeletal muscle growth