An intronic Ikaros-binding element mediates retinoic acid suppression of the kappa opioid receptor gene, accompanied by histone deacetylation on the promoters.
The mouse kappa opioid receptor (KOR) gene is constitutively expressed in mouse embryonal carcinoma P19 stem cells and suppressed by retinoic acid (RA) in cells undergoing neuronal differentiation. A negative regulatory element is located within intron 1 of the KOR gene, which contains an Ikaros (Ik)-binding site (GGGAAgGGGAT). This sequence is an Ik-1 respondive, functionally negative element as demonstrated in the context of both natural KOR and heterologous promoters. The two underlined G residues of the second half-site are critical for Ik-1 binding and Ik-mediated repression of the KOR gene. RA induces Ik-1 expression within 1 day of treatment and suppresses KOR expression between 2 and 3 days. Overexpression of Ik-1 in P19 suppresses endogenous KOR gene expression, accompanied by increased binding of Ik-1 to the Ik-binding site and chromatin histone deacetylation on KOR promoters. It is proposed that in an RA-induced P19 differentiation model, RA elevates Ik-1 expression, which recruits histone deacetylase to intron 1 of the KOR gene and silences KOR gene promoters.
Hu
X
X
Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455-0217, USA.
Bi
J
J
Loh
H H
HH
Wei
L N
LN
D000107:Acetylation; D000818:Animals; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D051740:Ikaros Transcription Factor; D007438:Introns; D051379:Mice; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D017473:Receptors, Opioid, kappa / Q000096:biosynthesis / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D006657:Histones; D012333:RNA, Messenger; D017473:Receptors, Opioid, kappa; D014157:Transcription Factors; C497238:Zfpn1a1 protein, mouse; D051740:Ikaros Transcription Factor; D014212:Tretinoin