Figure 1.

Mechanisms controlling the switch from white to brown phenotype. Studies by Kajimura et al. (2008) demonstrate that PRDM16 can interact with either PGC-1α/β or CtBPs to activate brown genes or to suppress white gene expression, respectively. Studies by Parker and colleagues (Christian et al. 2006; Parker et al. 2006; Powelka et al. 2006) have also shown that RIP140 in association with CtBPs can suppress mitochondrial gene expression in white adipocytes. It will be interesting to determine additional functions for PRDM16 and RIP140 coregulator complexes in controlling other features of the brown versus white fat cell phenotype including angiogenesis and adipokine production. Furthermore, knowledge of the involvement of changes in redox state (i.e., hypoxia and nutrients) in controlling these processes will be very informative for the development of therapeutics for obesity-associated disorders.