Association of peroxisome proliferator-activated receptor and Hsp72

In an effort to understand the relationship between a 72-kDa heat shock protein (Hsp72) and peroxisome proliferator-activated receptors (PPARs), we have characterized their interaction using clofibric acid-Sepharose chromatography and co-immunoprecipitation with antisera raised against either rat PPAR (rPPAR) or Hsp72. First, we observed that both rPPAR and Hsp72 elute in a clofibrate-dependent manner from the clofibric acid-Sepharose matrix. Second, we found that immunoprecipitation of either protein from solution resulted in the precipitation of the other. This result was obtained from rat liver cytosol, from Spodoptera frugiperda (Sf9) insect cells expressing rPPAR, and from reticulocyte lysate rPPAR expression systems. These results suggest that Hsp72 and rPPAR form a complex in vivo and that Hsp72 may play a role in the folding, subcellular localization, and/or signaling pathway of PPARs.