Transcriptional regulation by the gamma 5 subunit of a heterotrimeric G protein during adipogenesis

The adipocyte enhancer-binding protein (AEBP1) is a novel transcriptional r epressor with carboxypeptidase activity. A two-hybrid screen was conducted to identify components of AEBP1 that might be important in regulating its a ctivity. The gamma 5 subunit of a heterotrimeric G protein was shown to bin d specifically to AEBP1 and to attenuate its transcriptional repression act ivity. Adipogenic stimulation selectively decreased the G gamma 5 level and enhanced the transcriptional repression activity of AEBP1 during mitotic c lonal expansion at the onset of adipogenesis. Thus, the actions of G gamma 5 and AEBP1 are directly linked, which could provide the basis for the regu lation of transcription at the onset of differentiation. This report shows that a signal-transducing molecule is involved, by direct protein-protein i nteraction, in the regulation of transcription during adipogenesis.