Unliganded T3R, but not its oncogenic variant, v-erbA, suppresses RAR-dependent transactivation by titrating out RXR

Item Type:	Article
Title:	Unliganded T3R, but not its oncogenic variant, v-erbA, suppresses RAR-dependent transactivation by titrating out RXR
Creators Name:	Barettino, D. and Bugge, T.H. and Bartunek, P. and Vivanco Ruiz, M.D. and Sonntag-Buck, V. and Beug, H. and Zenke, M. and Stunnenberg, H.G.
Abstract:	V-erbA is thought to be an antagonist of thyroid hormone receptor (T3R) function. Here we show that unliganded T3R, but not v-erbA, suppresses retinoic acid (RA)-dependent induction of the RAR-beta 2 promoter by competing for the common dimerization partner, the retinoid X receptor (RXR). Firstly, T3R suppression can be alleviated by co-transfection of RXR. Secondly, T3R, but not v-erbA, competes with RAR for RXR and causes the dissociation of a preformed RAR/RXR-RARE ternary complex in vitro. A single point mutation located in the dimerization interface of v-erbA (Pro349 to Ser) abolishes the transdominant phenotype when introduced at the respective position in T3R. The hypertransforming v-erbA variant r12, in which this mutation is reversed (Ser349 to Pro) suppresses RA-induced differentiation in chicken erythroid progenitors, while v-erbA does not. Our data thus suggest that unliganded T3R and v-erbA act as dominant suppressors through mechanistically distinct pathways.
Keywords:	Erythroid Differentiation, Oncogene, RAR, RXR, T(3)R, v-erbA
Source:	EMBO Journal
ISSN:	0261-4189
Publisher:	Oxford University Press
Volume:	12
Number:	4
Page Range:	1343-1354
Date:	April 1993
Official Publication:	http://www.ncbi.nlm.nih.gov/pmc/articles/PMC413346/
PubMed:	View item in PubMed

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