Thyroid hormone-induced juxtaposition of regulatory elements/factors and chromatin remodeling of Crabp1 dependent on MED1/TRAP220.
The cellular retinoic acid binding protein I gene is induced by thyroid hormone (T3) through a T3 response element (TRE) approximately 1 kb upstream of the basal promoter. The upstream region is organized into a positioned nucleosomal array with the N1 nucleosome spanning the GC box region. T3 induces apparent interactions between chromatin segments containing the TRE and the GC box regions and the sliding of upstream nucleosomes toward N1 with concomitant N1 remodeling. Concurrently, the chromatin-remodeling factor BRM is replaced by BRG1 and histones are hyperacetylated. All these events are abolished in Med1/Trap220 null cells, indicating a key role for TRAP/Mediator in these processes. A MED1/TRAP220-containing Mediator complex constitutively occupies the GC box region but not the TRE, serving as a nexus for distal and proximal factors. This indicates new TRAP/Mediator functions in facilitating ultimate recruitment and function of RNA polymerase II and the general transcription machinery.
Park
Sung Wook
SW
Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
Li
Guangjin
G
Lin
Ya-Ping
YP
Barrero
Maria J
MJ
Ge
Kai
K
Roeder
Robert G
RG
Wei
Li-Na
LN
D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D004706:Endodeoxyribonucleases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D056913:Mediator Complex Subunit 1; D051379:Mice; D018345:Mice, Knockout; D009707:Nucleosomes / Q000502:physiology; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D020218:Response Elements; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D014284:Triiodothyronine / Q000502:physiology*
C538856:Med1 protein, mouse; D056913:Mediator Complex Subunit 1; D009707:Nucleosomes; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; C082927:retinoic acid binding protein I, cellular; D014284:Triiodothyronine; D004706:Endodeoxyribonucleases; C492249:Mbd4 protein, mouse