Mdm2 controls CREB-dependent transactivation and initiation of adipocyte differentiation
Hallenborg, P Feddersen, S Francoz, S Murano, I Sundekilde, U Petersen, R K Akimov, V Olson, M V Lozano, G Cinti, S Gjertsen, B T Madsen, L Marine, Chris Blagoev, B Kristiansen, K # ×
Cell Death and Differentiation vol:19 issue:8 pages:1381-1389
The role of the E3 ubiquitin ligase murine double minute 2 (Mdm2) in regulating the stability of the p53 tumor suppressor is well documented. By contrast, relatively little is known about p53-independent activities of Mdm2 and the role of Mdm2 in cellular differentiation. Here we report a novel role for Mdm2 in the initiation of adipocyte differentiation that is independent of its ability to regulate p53. We show that Mdm2 is required for cAMP-mediated induction of CCAAT/enhancer-binding protein δ (C/EBPδ) expression by facilitating recruitment of the cAMP regulatory element-binding protein (CREB) coactivator, CREB-regulated transcription coactivator (Crtc2)/TORC2, to the c/ebpδ promoter. Our findings reveal an unexpected role for Mdm2 in the regulation of CREB-dependent transactivation during the initiation of adipogenesis. As Mdm2 is able to promote adipogenesis in the myoblast cell line C2C12, it is conceivable that Mdm2 acts as a switch in cell fate determination.