In Vivo Interaction of Steroid Receptor Coactivator (SRC)-1 and the Activation Function-2 Domain of the Thyroid Hormone Receptor (TR) β in TRβ E457A Knock-In and SRC-1 Knockout mice
In Vivo Interaction of Steroid Receptor Coactivator (SRC)-1 and the Activation Function-2 Domain of the Thyroid Hormone Receptor (TR) β in TRβ E457A Knock-In and SRC-1 Knockout mice
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DOI：
10.1210/en.2009-0093
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发表时间：
2009-08-01
期刊：
影响因子：
4.8
通讯作者：
Weiss, Roy E.
中科院分区：
文献类型：
--
作者：
Alonso, Manuela;Goodwin, Charles;Weiss, Roy E.
甲状腺激素（TH）受体（TR）-β的激活功能-2（AF-2）结构域是调节TH依赖性基因转录的核辅激活因子（NCoA）的TH依赖性结合位点。与此相反，推定的AF-1结构域是一个TH-独立的区域与NCoA相互作用。我们通过评估TR β中AF-2结构域联合破坏（由于点突变（E457 A））和NCoA之一（类固醇受体共激活因子（SRC）-1）缺失）小鼠的甲状腺功能，确定AF-2结构域和NCoA相互作用的特异性。选择E457 A突变是因为它在体外消除NCoA募集，同时保留正常的TH结合和辅阻遏物相互作用，导致对TH的抗性。在基线时，纯合敲入（TR β（E457 A/E457 A））小鼠中SRC-1的破坏使TH抗性程度恶化，导致血清T-4和TSH升高。在TH剥夺期间，AF-2和SRC-1的破坏导致TSH升高50%，这表明SRC-1在AF-2结构域之外相互作用。因此，1）在TH剥夺期间，SRC-1是激活下丘脑-垂体-甲状腺轴所必需的; 2）TSH的配体依赖性抑制需要完整的AF-2; 3）SRC-1可能与TR β或TR α的另一个区域相互作用以调节垂体中的TH作用。本报告证明了NCoA在体内的双重相互作用：TH非依赖性上调可能通过另一个结构域和TH依赖性下调通过AF-2结构域。（内分泌学150：3927-3934，2009）
The activation function-2 (AF-2) domain of the thyroid hormone (TH) receptor (TR)-beta is a TH-dependent binding site for nuclear coactivators (NCoA), which modulate TH-dependent gene transcription. In contrast, the putative AF-1 domain is a TH-independent region interacting with NCoA. We determined the specificity of the AF-2 domain and NCoA interaction by evaluating thyroid function in mice with combined disruption of the AF-2 domain in TR beta, due to a point mutation (E457A), and deletion of one of the NCoAs, steroid receptor coactivator (SRC)-1. The E457A mutation was chosen because it abolishes NCoA recruitment in vitro while preserving normal TH binding and corepressor interactions resulting in resistance to TH. At baseline, disruption of SRC-1 in the homozygous knock-in (TR beta(E457A/E457A)) mice worsened the degree of resistance to TH, resulting in increased serum T-4 and TSH. During TH deprivation, disruption of AF-2 and SRC-1 resulted in a TSH rise 50% of what was seen when AF-2 alone was removed, suggesting that SRC-1 was interacting outside of the AF-2 domain. Therefore, 1) during TH deprivation, SRC-1 is necessary for activating the hypothalamic-pituitary-thyroid axis; 2) ligand-dependent repression of TSH requires an intact AF-2; and 3) SRC-1 may interact with the another region of the TR beta or the TR alpha to regulate TH action in the pituitary. This report demonstrates the dual interaction of NCoA in vivo: the TH-independent up-regulation possibly through another domain and TH-dependent down-regulation through the AF-2 domain. (Endocrinology 150: 3927-3934, 2009)