β-carotene as a dietary factor affecting expression of genes connected with carotenoid, vitamin A and lipid metabolism in the subcutaneous and omental adipose tissue of beef cattle

Abstract

Adipose tissue in meat, especially subcutaneous fat, is not appreciated by consumers as it is considered unhealthy. The effects of β-carotene (βC) on the expression of ten genes related to carotenoid, vitamin A (VA) or lipid metabolism were evaluated in subcutaneous and omental (visceral) adipose tissue of Simmental crossbred steers receiving various βC treatments (0, 600, 1200 and 1800 mg/d). Two carotenoid oxidative cleavage genes (β-carotene- 15,15 -monooxygenase (BCMO1) and β-carotene-9 ,10 -dioxygenase (BCO2)) were up-regulated and three VA metabolic genes (retinoid X receptor α (RXRA), retinal reductase (RALDH) and lecithin-retinol acyltransferase (LRAT)) were down-regulated in subcutaneous and omental adipose tissues. Gene encoding peroxisome proliferator-activated receptor γ (PPARG) involved in adipocyte differentiation and lipogenesis was down-regulated in both examined fat tissues. For the omental adipose tissue, the lipogenesis gene (fatty acid synthase (FAS)) and the two lipolysis genes (hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL)) were down-regulated, but another lipogenesis gene (acetyl-CoA carboxylase (ACC)) was up-regulated. First of all, the addition of βC in the diet may inhibit the expression of the major adipogenesis gene PPARG, and increase the expression of genes involved in βC catabolism in adipose tissue of beef cattle. An effective βC dose to regulate the expression of genes connected with carotenoid, VA and lipid metabolism would be at least 600 mg/d.