Diverse peroxisome proliferator-activated receptors bind to the peroxisome proliferator-responsive elements of the rat hydratase/dehydrogenase and fatty acyl-CoA oxidase genes but differentially induce expression.
The ability of peroxisome proliferator-activated receptors (PPARs) to induce expression of a reporter gene linked to a peroxisome proliferator-responsive element (PPRE) from either the rat enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase gene or acyl-CoA oxidase [acyl-CoA:oxygen 2-oxidoreductase, EC 1.3.3.6] gene was examined by transient transfection assays in COS cells. Mouse and rat PPARs, as well as Xenopus PPAR alpha (xPPAR alpha) could induce expression of a reporter gene linked to the hydratase/dehydrogenase PPRE in the presence of the peroxisome proliferators ciprofibrate or Wy-14,643, whereas xPPAR beta and xPPAR gamma were ineffective. A similar induction of expression of a reporter gene linked to the acyl-CoA oxidase PPRE was observed with all PPARs except xPPAR beta. Extracts from cells transfected with PPAR-encoding genes contained factors that bound to both PPREs. In vitro synthesized PPARs could interact weakly with both PPREs; however, binding of each PPAR to both PPREs was significantly increased by the addition of COS cell nuclear extracts, demonstrating that efficient PPAR/DNA binding requires auxiliary cofactors. One cofactor was identified as the 9-cis-retinoic acid receptor, RXR alpha (retinoid X receptor alpha). Cooperative DNA binding and heteromerization between RXR alpha and each of the PPARs could be seen with both PPREs. Our results demonstrate that PPAR/PPRE binding and cooperativity with RXR alpha (and other cofactors) are obligatory but not necessarily sufficient for peroxisome proliferator-dependent transcription induction and that distinct PPREs can selectively mediate induction by particular PPARs.
Department of Biochemistry, McMaster University, Hamilton, ON, Canada.
S L
SL
Marcus
K S
KS
Miyata
B
B
Zhang
S
S
Subramani
R A
RA
Rachubinski
J P
JP
Capone
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000235:genetics*; D042962:Acyl-CoA Oxidase; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004746:Enoyl-CoA Hydratase / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D007535:Isomerases / Q000235:genetics*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008114:Liver Neoplasms, Experimental; D051379:Mice; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009838:Oligodeoxyribonucleotides; D010088:Oxidoreductases / Q000235:genetics*; D063994:Peroxisomal Bifunctional Enzyme; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D015183:Restriction Mapping; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014981:Xenopus
D009097:Multienzyme Complexes; D009838:Oligodeoxyribonucleotides; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D004247:DNA; D010088:Oxidoreductases; D015094:3-Hydroxyacyl CoA Dehydrogenases; D042962:Acyl-CoA Oxidase; C576254:Ehhadh protein, mouse; D004746:Enoyl-CoA Hydratase; D063994:Peroxisomal Bifunctional Enzyme; D007535:Isomerases