p300 functions as a coactivator for the peroxisome proliferator-activated receptor alpha.

The integrator protein, p300, was demonstrated to interact with mouse peroxisome proliferator-activated receptor alpha in a ligand-enhanced manner. The PPARalpha-interacting domain of p300 was mapped to amino acids 39-117 which interacted strongly with PPARalpha but did not interact with retinoic acid receptor-gamma or retinoid X receptor-alpha. Amino acids within the carboxyl terminus of PPARalpha as well as residues within the hinge region were required for ligand-dependent interaction with p300. p300 enhanced the transcriptional activation properties of PPARalpha and, therefore, can be considered a bona fide coactivator for this nuclear receptor. These observations extend the group of p300-interacting proteins to include mPPARalpha and further characterize the molecular mechanisms of PPARalpha-mediated transcriptional regulation.