This invention relates generally to compositions and methods which utilization nuclear receptors for regulating adipogenesis in cells. Specifically, the invention is directed to compositions which regulate transcription factor PPARγ. and enhance or inhibit the transcription of genes responsible for directing cell differentiation towards a pathway of adipogenesis. More specifically, disclosed herein is a novel polypeptide coactivator of PPARγ, and fragments thereof, which possess coactivator or corepressor activity. Also related are nucleotide sequences which express these polypeptides. Also disclosed is an interfering RNA that may be used to inhibit adipogenesis.