In:
Genes & Development, Cold Spring Harbor Laboratory, Vol. 20, No. 20 ( 2006-10-15), p. 2871-2886
Abstract:
Negative feedback regulation of the proopiomelanocortin ( POMC ) gene by the glucocorticoid (Gc) receptor (GR) is a critical feature of the hypothalamo–pituitary–adrenal axis, and it is in part exerted by trans -repression between GR and the orphan nuclear receptors related to NGFI-B. We now show that Brg1, the ATPase subunit of the Swi/Snf complex, is essential for this trans -repression and that Brg1 is required in vivo to stabilize interactions between GR and NGFI-B as well as between GR and HDAC2. Whereas Brg1 is constitutively present at the POMC promoter, recruitment of GR and HDAC2 is ligand-dependent and results in histone H4 deacetylation of the POMC locus. In addition, GR-dependent repression inhibits promoter clearance by RNA polymerase II. Thus, corecruitment of repressor and activator at the promoter and chromatin modification jointly contribute to trans -repression initiated by direct interactions between GR and NGFI-B. Loss of Brg1 or HDAC2 should therefore produce Gc resistance, and we show that ∼50% of Gc-resistant human and dog corticotroph adenomas, which are the hallmark of Cushing disease, are deficient in nuclear expression of either protein. In addition to providing a molecular basis for Gc resistance, these deficiencies may also contribute to the tumorigenic process.
Type of Medium:
Online Resource
ISSN:
0890-9369
,
1549-5477
Language:
English
Publisher:
Cold Spring Harbor Laboratory
Publication Date:
2006
detail.hit.zdb_id:
1467414-2
SSG:
12