A 45 kDa protein related to PPAR gamma 2, induced by peroxisome proliferators, is located in the mitochondrial matrix

Besides their involvement in the control of nuclear gene expression by acti vating several peroxisome proliferator-activated receptors (PPARs), peroxis ome proliferators influence mitochondrial activity. By analogy with the pre vious characterization of a mitochondrial T3 receptor (p43), we searched fo r the presence of a peroxisome proliferator target in the organelle, Using several antisera raised against different domains of PPARs, we demonstrated by Western blotting, immunoprecipitation and electron microscopy experimen ts, that a 45 kDa protein related to PPAR gamma 2 (mt-PPAR) is located in t he matrix of rat liver mitochondria. In addition, we found that the amounts of mt-PPAR are increased by clofibrate treatment. Moreover, in EMSA experi ments mt-PPAR bound to a DR2 sequence located in the mitochondrial D-loop, by forming a complex with p43. Last, studies of tissue-specific expression indicated that mt-PPAR is detected in mitochondria of all tissues tested ex cept the brain in amounts positively related to p43 abundance, (C) 2000 Fed eration of European Biochemical Societies. Published by Elsevier Science B. V. All rights reserved.