Cloning and identification of mouse steroid receptor coactivator-1 (mSRC-1), as a coactivator of peroxisome proliferator-activated receptor gamma.
Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear receptor superfamily, is expressed predominantly in adipose tissue. Forced expression of the two isoforms of this receptor, PPARgamma1 and PPARgamma2, in fibroblasts initiates a transcriptional cascade that leads to the development of adipocyte phenotype. Using the yeast two-hybrid system and GAL4-PPARgamma as bait to screen mouse liver cDNA library, we isolated a mouse steroid receptor coactivator (mSRC-1) involved in nuclear hormone receptor transcriptional activity as a mPPARgamma interactive protein. mSRC-1 cDNA we isolated contains an open reading frame of 1447 amino acids and encodes a new member of the basic helix-loop-helix-PAS domain family. We show that the binding of mSRC-1 to mPPARgamma is ligand independent and coexpression of mSRC-1 with mPPARgamma increases the transcriptional activity of mPPARgamma in the presence of mPPARgamma ligand. We have identified the presence of two putative mPPARgamma binding sites in the mSRC-1, one between residues 620 and 789, and the second between residues 1231 and 1447. These two regions exhibit different degrees of binding affinity for mPPARgamma. We also show that mSRC-1 exhibits its own constitutive transcriptional activity in the yeast as well as in mammalian cells. These results suggest that mSRC-1 interacts with PPARgamma and plays a role in the PPARgamma-mediated signaling pathway.
Zhu
Y
Y
Department of Pathology, Northwestern University Medical School, Chicago, IL 60611, USA.
Qi
C
C
Calandra
C
C
Rao
M S
MS
Reddy
J K
JK
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D051548:Histone Acetyltransferases; D051379:Mice; D008830:Microbodies / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D056920:Nuclear Receptor Coactivator 1; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D018076:DNA, Complementary; D009687:Nuclear Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D051548:Histone Acetyltransferases; C538861:Ncoa1 protein, mouse; D056920:Nuclear Receptor Coactivator 1