Examination of Ligand-Dependent Coactivator Recruitment by Peroxisome Proliferator-Activated Receptor-α(PPARα)

Abstract

The ligand-dependent recruitment of coactivators to peroxisome proliferator-activated receptor-α(PPARα) was examined. PPAR-binding protein (PBP), PPARγcoactivator-1α(PGC-1α), steroid receptor coactivator-1 (SRC-1), and CBP/p300-interacting transactivator with ED-rich tail 2 (CITED2) affected PPARαactivity in the presence of Wy-14,643. The effects on PPARαactivity in light of increased or decreased expression of these coactivators were qualitatively different depending on the ligand examined. Diminished expression of PGC-1α, SRC-1, or PBP by RNAi plasmids affected natural or synthetic agonist activity whereas only Wy-14,643 was affected by decreased PGC-1α. The interaction of PPARαwith an LXXLL-containing peptide library showed ligand-specific patterns, indicative of differences in conformational change. The association of coactivators to PPARαoccurs predominantly via the carboxyl-terminus and mutating456LHPLL to456LHPAA resulted in a dominant-negative construct. This research confirms that coactivator recruitment to PPARαis ligand-dependent and that selective receptor modulators (SRMs) of this important protein are likely.