FIGURE 8.

Model for the regulation of CRABP-II expression during adipogenesis and in mature adipocytes. The classical adipocyte differentiation inducers, insulin, IBMX, and dexamethasone (dex), all repress the expression of CRABP-II. IBMX increases cellular levels of cAMP leading to activation of PKA. Activated PKA phosphorylates CREB, which positively regulates the expression of its direct target gene CREM. In turn, CREM associates with a CRE in the first intron of CRABP-II and recruits HDAC1 to repress CRABP-II transcription. Dexamethasone activates GR. In turn, GR binds to a GRE in the CRABP-II promoter and negatively regulates CRABP-II expression. The details of the mechanism through which insulin represses CRABP-II expression remain to be explored. In mature adipocytes, low levels of expression of CRABP-II are maintained by direct repression by C/EBPα.