The orphan nuclear receptor TR4 Is a vitamin A-activated nuclear receptor

X. Edward Zhou, Kelly M. Suino-Powell, Yong Xu, Cee Wah Chan, Osamu Tanabe, Schoen W. Kruse, Ross Reynolds, James Douglas Engel, H. Eric Xu

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)

Abstract

Testicular receptors 2 and 4 (TR2/4) constitute a subgroup of orphan nuclear receptors that play important roles in spermatogenesis, lipid and lipoprotein regulation, and the development of the central nervous system. Currently, little is known about the structural features and the ligand regulation of these receptors. Here we report the crystal structure of the ligand-free TR4 ligand binding domain, which reveals an autorepressed conformation. The ligand binding pocket of TR4 is filled by the C-terminal half of helix 10, and the cofactor binding site is occupied by the AF-2 helix, thus preventing ligand-independent activation of the receptor. However, TR4 exhibits constitutive transcriptional activity on multiple promoters, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, or ligand binding substantially reduce the transcriptional activity of this receptor. Importantly, both retinol and retinoic acid are able to promote TR4 to recruit coactivators and to activate a TR4-regulated reporter. These findings demonstrate that TR4 is a ligand-regulated nuclear receptor and suggest that retinoids might have a much wider regulatory role via activation of orphan receptors such as TR4.

Original languageEnglish
Pages (from-to)2877-2885
Number of pages9
JournalJournal of Biological Chemistry
Volume286
Issue number4
DOIs
Publication statusPublished - 2011 Jan 28

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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