Identification of Allsoteric Ligands for Hepatic Nuclear Factor 4-alpha

描述(申请人提供)：肝细胞核因子4-α(HNF4)是核受体转录因子家族的成员。HNF4控制肝脏和胰腺中与胰岛素和葡萄糖产生相关的基因。HNF4基因突变会导致青年1型糖尿病(MODY1)的成熟发作和人类的高胰岛素血症(HH)。核受体超家族的成员在其配体结合域(LBD)内有一个疏水口袋。传统的药物筛选策略在已知的孤立LBD结构的指导下，利用这些口袋。该领域缺乏全长受体的高分辨率结构，因此没有考虑这些蛋白质中其他可用药部位的可能性。我们已经获得了一个完整的晶体结构HNF4同源二聚体，与其DNA反应元件形成了一个功能揭示的络合物。这种结构出人意料地揭示了结构域结合处的两个位置，小分子可以在那里结合。我们的突变研究以及先前对翻译后修饰的了解表明，这些位点可以变构调节HNF4的DNA亲和力。我们建议一个高通量的筛选活动，以及利用HNF4中这些新位点的验证性分析和机制研究。我们的目标是确定使某些MODY1和HH疾病人群受益的DNA结合增强剂，在这些人群中，受体与DNA的结合因HNF4的点突变而受到损害。

DESCRIPTION (provided by applicant): The hepatocyte nuclear factor 4-alpha (HNF4) is a member of the nuclear receptor family of transcription factors. HNF4 controls genes in the liver and pancreas related to insulin and glucose production. Mutations in HNF4 cause Maturity Onset of Diabetes in Young 1 (MODY1), and hyperinsulinemic hypoglycemia (HH) in humans. Members of the nuclear receptor superfamily have a hydrophobic pocket inside their ligand binding domains (LBDs). Traditional drug screening strategies exploit these pockets, guided by known structures of isolated LBDs. The field has lacked high-resolution structures for full-length receptors, and therefore not considered the possibility of other druggable sites elsewhere in these proteins. We have obtained a complete crystal structure HNF4 homodimer, in a functionally revealing complex with its DNA response element. This structure unexpectedly reveals two sites at domain-domain junctions, where small molecules could bind. Our mutational studies, and previous knowledge of post-translational modifications, show these sites can allosterically regulate the DNA affinity of HNF4 . We propose a high-throughput screening campaign, together with confirmatory assays and mechanistic studies that exploit these new sites in HNF4 . Our goal is to identify potentiators of DNA binding that benefit certain MODY1 and HH disease populations where receptor-DNA binding is compromised by point mutations in HNF4 .