RETINOIC ACID MODULATES RETINOID-X-RECEPTOR-ALPHA AND RETINOIC ACID RECEPTOR-ALPHA LEVELS OF CULTURED BROWN ADIPOCYTES

A novel potential regulatory pathway of brown adipose tissue (BAT) the rmogenesis was recently recognized after identifying retinoic acid (RA ) as a transcriptional activator of the uncoupling protein (UCP) gene, Here we provide evidence that the UCP responsiveness to RA in primary cultures of brown adipocytes involves RA receptor alpha (RAR alpha), and show, in the same system and also in CHO cells, that RA down-regul ates the steady-state levels of RAR alpha and especially of retinoid X receptor alpha, suggesting autoregulation of the retinoid pathway and therefore supporting the idea of a physiological role for it in contr olling the thermogenic capacity of BAT. (C) 1997 Federation of Europea n Biochemical Societies.