Active repression by unliganded retinoid receptors in development: less is sometimes more.
The retinoid receptors have major roles throughout development, even in the absence of ligand. Here, we summarize an emerging theme whereby gene repression, mediated by unliganded retinoid receptors, can dictate cell fate. In addition to activating transcription, retinoid receptors actively repress gene transcription by recruiting cofactors that promote chromatin compaction. Two developmental processes for which gene silencing by the retinoid receptors is essential are head formation in Xenopus and skeletal development in the mouse. Inappropriate repression, by oncogenic retinoic acid (RA)**Abbreviations used in this paper: APL, acute promyelocytic leukemia; dnRARalpha, dominant-negative version of the RARalpha; E, embryonic age; HDAC, histone deacetylase; LCoR, ligand-dependent corepressor; NCoR, nuclear receptor corepressor; RA, retinoic acid; RAR, RA receptor; RARE, RXR homodimer bound to bipartite response element; RXR, retinoid X receptor; TSA, trichostatin A; CYP26, cytochrome p450, 26; TR, thyroid hormone receptor. receptor (RAR) fusion proteins, blocks myeloid differentiation leading to a rare form of leukemia. Our current understanding of the developmental role of retinoid repression and future perspectives in this field are discussed.
Weston
Andrea D
AD
Institute for Systems Biology, 1441 N. 34th St., Seattle, WA 98103, USA. aweston@systemsbiology.org
Blumberg
Bruce
B
Underhill
T Michael
TM
D000818:Animals; D019521:Body Patterning / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D020868:Gene Silencing / Q000502:physiology; D006801:Humans; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D037941:Silencer Elements, Transcriptional / Q000235:genetics; D014714:Vertebrates / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins