A corepressor and chicken ovalbumin upstream promoter transcriptional factor proteins modulate peroxisome proliferator-activated receptor-gamma2/retinoid X receptor alpha-activated transcription from the murine lipoprotein lipase promoter.
Complex physiological stimuli differentially regulate the tissue-specific transcription of the lipoprotein lipase (LPL) gene. A conserved DNA recognition element (-171 to -149 bp) within the promoter functions as a transcriptional enhancer when bound by the peroxisome proliferator-activated receptor-gamma2 (PPARgamma2)/retinoid X receptor alpha (RXRalpha) heterodimer, but serves as a transcriptional silencer in the presence of unidentified double and single stranded DNA-binding proteins. To address this apparent paradox, the current study examined the effect of two classes of candidate comodulatory proteins, COUP-TF (chicken ovalbumin upstream promoter transcriptional factor) and the corepressor SMRT (silencing mediator of retinoic acid receptor and thyroid receptor). The expression of COUP-TF was detected by Western and Northern blots in a preadipocyte 3T3-L1 cell model during periods corresponding to increased LPL transcription. Cotransfection of COUP-TF expression constructs in the renal epithelial 293T cell line significantly increased transcription from the LPL promoter in synergy with PPARgamma2/RXRalpha heterodimers. The COUP-TFII (ARP-1) protein specifically bound the LPL PPAR recognition element inelectromobility shift assays and interacted directly with the ligand-binding domain of PPARgamma in pull-down experiments. In contrast, cotransfection of SMRT repressed PPARgamma2/ RXRalpha-mediated LPL transcription in the absence or presence of COUP-TFII (ARP-1). The interaction between PPARgamma2 and SMRT localized to the receptor-interactive domain 2 (amino acids 1260-1495) of the SMRT protein based on cotransfection and pull-down assays. These in vitro data indicate that COUP-TF proteins and SMRT modulate PPARgamma-mediated LPL transcription in the 293T cell line.
Robinson
C E
CE
Zoology Department, University of Oklahoma, Norman 73019, USA.
Wu
X
X
Nawaz
Z
Z
Onãte
S A
SA
Gimble
J M
JM
D016475:3T3 Cells; D000818:Animals; D051838:COUP Transcription Factor I; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D004357:Drug Synergism; D004622:Embryo, Mammalian; D015870:Gene Expression; D006801:Humans; D007668:Kidney; D008071:Lipoprotein Lipase / Q000235:genetics*; D051379:Mice; D056985:Nuclear Receptor Co-Repressor 2; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism / Q000502:physiology*; D018168:Receptors, Retinoic Acid / Q000502:physiology*; D011987:Receptors, Steroid; D012097:Repressor Proteins / Q000235:genetics*; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection
D051838:COUP Transcription Factor I; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D004247:DNA; D004268:DNA-Binding Proteins; D008071:Lipoprotein Lipase; D056985:Nuclear Receptor Co-Repressor 2; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D011987:Receptors, Steroid; D012097:Repressor Proteins; D047488:Retinoid X Receptors; D014157:Transcription Factors; C539130:NCOR2 protein, human; C497589:NR2F1 protein, human; C539131:Ncor2 protein, mouse; C497590:Nr2f1 protein, mouse; C497587:Nr2f2 protein, mouse; C095569:NR2F2 protein, human