PRIC320, a transcription coactivator, isolated from peroxisome proliferator-binding protein complex.
Ciprofibrate, a potent peroxisome proliferator, induces pleiotropic responses in liver by activating peroxisome proliferator-activated receptor alpha (PPARalpha), a nuclear receptor. Transcriptional regulation by liganded nuclear receptors involves the participation of coregulators that form multiprotein complexes possibly to achieve cell and gene specific transcription. SDS-PAGE and matrix-assisted laser desorption/ionization reflection time-of-flight mass spectrometric analyses of ciprofibrate-binding proteins from liver nuclear extracts obtained using ciprofibrate-Sepharose affinity matrix resulted in the identification of a new high molecular weight nuclear receptor coactivator, which we designated PRIC320. The full-length human cDNA encoding this protein has an open-reading frame that codes for a 320kDa protein containing 2882 amino acids. PRIC320 contains five LXXLL signature motifs that mediate interaction with nuclear receptors. PRIC320 binds avidly to nuclear receptors PPARalpha, CAR, ERalpha, and RXR, but only minimally with PPARgamma. PRIC320 also interacts with transcription cofactors CBP, PRIP, and PBP. Immunoprecipitation-immunoblotting as well as cellular localization studies confirmed the interaction between PPARalpha and PRIC320. PRIC320 acts as a transcription coactivator by stimulating PPARalpha-mediated transcription. We conclude that ciprofibrate, a PPARalpha ligand, binds a multiprotein complex and PRIC320 cloned from this complex functions as a nuclear receptor coactivator.
The Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
Sailesh
S
Surapureddi
Navin
N
Viswakarma
Songtao
S
Yu
Dongsheng
D
Guo
M Sambasiva
MS
Rao
Janardan K
JK
Reddy
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D002995:Clofibric Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005240:Feasibility Studies; D058607:Fibric Acids; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D047495:PPAR gamma / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods; D051381:Rats; D011916:Rats, Inbred F344; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
D004268:DNA-Binding Proteins; D058607:Fibric Acids; D009687:Nuclear Proteins; D047495:PPAR gamma; D015534:Trans-Activators; D014157:Transcription Factors; D002995:Clofibric Acid; D004265:DNA Helicases; C504643:CHD9 protein, human; C019304:ciprofibrate