Reproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Durham, NC 27709, USA.
Precision Medicine Lab, Kloosterstraat 9, 5349 AB, Oss, Netherlands.
Sci Signal. 2020 Sep 22;13(650):eaaw4653. doi: 10.1126/scisignal.aaw4653.
A homozygous missense mutation in the gene encoding the estrogen receptor α (ERα) was previously identified in a female patient with estrogen insensitivity syndrome. We investigated the molecular features underlying the impaired transcriptional response of this mutant (ERα-Q375H) and four other missense mutations at this position designed to query alternative mechanisms. The identity of residue 375 greatly affected the sensitivity of the receptor to agonists without changing the ligand binding affinity. Instead, the mutations caused changes in the affinity of coactivator binding and alterations in the balance of coactivator and corepressor recruitment. Comparisons among the transcriptional regulatory responses of these six ERα genotypes to a set of ER agonists showed that both steric and electrostatic factors contributed to the functional deficits in gene regulatory activity of the mutant ERα proteins. ERα-coregulator peptide binding in vitro and RIME (rapid immunoprecipitation mass spectrometry of endogenous) analysis in cells showed that the degree of functional impairment paralleled changes in receptor-coregulator binding interactions. These findings uncover coupling between ligand binding and coregulator recruitment that affects the potency rather than the efficacy of the receptor response without substantially altering ligand binding affinity. This highlights a molecular mechanism for estrogen insensitivity syndrome involving mutations that perturb a bidirectional allosteric coupling between ligand binding and coregulator binding that determines receptor transcriptional output.
先前在一位雌激素不敏感综合征女性患者中发现了雌激素受体α（ERα）基因编码区的纯合错义突变。我们研究了该突变（ERα-Q375H）和在该位置设计的另外四个错义突变体的转录反应受损的分子特征，以探究其他替代机制。残基 375 的身份极大地影响了受体对激动剂的敏感性，而不改变配体结合亲和力。相反，这些突变导致共激活因子结合亲和力的变化，并改变共激活因子和核心抑制因子募集的平衡。对这六种 ERα 基因型对一组 ER 激动剂的转录调控反应进行比较表明，立体和静电因素都导致了突变体 ERα 蛋白基因调控活性的功能缺陷。体外的 ERα-共激活因子肽结合和细胞中的 RIME（内源性快速免疫沉淀质谱分析）分析表明，功能损伤的程度与受体-共激活因子结合相互作用的变化平行。这些发现揭示了配体结合和共激活因子募集之间的偶联作用，这种偶联作用影响受体反应的效力而不是功效，而不会显著改变配体结合亲和力。这突出了一种涉及突变的雌激素不敏感综合征的分子机制，这些突变会破坏配体结合和共激活因子结合之间的双向变构偶联，从而决定受体的转录输出。
