Fatty acids and retinoids act synergistically on adipose cell differentiation

Fatty acids and retinoids have been recently reported to act as positive effectors of adipose cell differentiation. Treatment of Ob1771 preadipose cells with selective agonists of retinoic acid receptors (RARs) in the presence of alpha-bromopalmitate, a non-metabolized fatty acid, led to a potent synergy in regard to the differentiation process, as assayed by the activity of glycerol-3-phosphate dehydrogenase. The most potent synergy was observed with compound CD 367, a potent agonist of RARs as well as with compound Am 580, a specific agonist of RAR alpha. Northern blot analysis of poly(A)+ mRNA from cells treated with compound CD 367, alpha-bromopalmitate, or a combination of both agonists, did not show a dramatic effect, if any, on the expression of RAR alpha, RAR gamma, RXR alpha and RXR beta genes. The results are discussed in light of the formation of heterodimers between RARs, RXRs and members of the family of peroxisome proliferator-activated receptors (PPARs).