MOLECULAR RECOGNITION IN STEROID SIGNALING

本研究试图利用X射线结晶学来了解类固醇核受体与类固醇结合和区分所涉及的丰富的界面化学。类固醇结合诱导受体构象变化，最终调节类固醇反应基因的转录。为了了解这一家族中类固醇识别的立体化学机制，可视化位于受体配体结合域(LBD)中的结合决定因素是必不可少的。对几种甾醇结合相互作用的交叉研究将揭示保守的识别机制和介导配体识别的独特的特定特征。因为许多LBD的点突变与类固醇不敏感、严重的发育障碍和癌症有关，我们寻找的结构可能被用来精确定位缺陷。雄激素受体过度产生，并与合成的睾酮类似物结合，是我们结构研究的第一个候选者。该受体可与用于前列腺癌治疗的类固醇和非类固醇雄激素拮抗剂特异性结合。许多点突变与雄激素不敏感综合征有关，并已被映射到其LBD。此外，似乎有越来越多的内分泌干扰物针对这种受体。我们建议扩大我们的初步衍射研究，以便：1)了解激动剂和拮抗剂识别的机制以及在单个受体中诱导的相应构象变化，以及2)通过分析多种不同的LBD-配体相互作用来理解类固醇识别的机制。

This study seeks to use X-ray crystallography to understand the rich interfacial chemistry involved in steroid binding and discrimination by the nuclear steroid receptors. The steroid binding induces receptor conformational changes that ultimately modulate transcription from steroid responsive genes. To understand the stereochemical mechanisms of steroid recognition in this family, it is essential to visualize the binding determinants located within the receptors' ligand binding domains (LBD). A cross examination of several sterol binding interactions will reveal both the conserved mechanisms of recognition and the unique specifying features that mediate ligand discrimination. Because point mutations in a number of LBDs have been associated with steroid insensitivity, profound developmental dysfunction and cancer, the structures we seek may be used to pinpoint the precise defects. The androgen receptor, overproduced and bound to a synthetic testosterone analog presents the fist candidate for our structural studies. This receptor specifically binds both steroid and non-steroid androgen antagonists used for the treatment of prostate cancer. Numerous point mutations associated with androgen insensitivity syndrome and have been mapped to its LBD. In addition, there are an increasing number of endocrine disrupters which appear to target this receptor. We propose to expand our preliminary diffraction studies in order to: 1) learn the mechanisms of agonist versus antagonist recognition and the corresponding conformational changes induced in a single receptor, and 2) understand the mechanisms of steroid discrimination through analysis of multiple different LBD-ligand interactions.