TRANSCRIPTIONAL CONTROL BY TWO DIABETES GENE PRODUCTS

基因特异性转录因子通过特异性识别靶基因的启动子区域并介导与共调节因子的相互作用来招募主要转录机制的其余部分来启动转录。大量的孟德尔人类疾病与编码这些转录因子的基因突变有关，事实上，最近的一项完整的人类基因组分析表明，转录因子是四种主要功能蛋白群之一，其种系突变导致各种人类疾病。我们的长期目标是了解这些转录因子调控基因的分子机制以及在这些转录因子中发现的致病突变的分子基础，这一建议将重点放在糖尿病上。hnf1α和hnf4α在器官发育和成人体内平衡中起着至关重要的作用，并且已被确定为单基因显性遗传性糖尿病的罪魁祸首基因产物。尽管它们的生理作用相似，但它们属于完全不同的转录因子家族，并通过其独特的结构和与不同的共调控因子相互作用，具有不同的基因调控机制。在多络合物形成过程中分子相互作用如何发生的详细结构信息尚不完全清楚。因此，我们提出(1)解决HNF1alpha和HNF4alpha及其靶DNA和其他功能伙伴在复合物中的晶体结构问题；(2)研究致糖尿病突变对蛋白质稳定性、体外DNA结合、蛋白-蛋白相互作用和体内整体转录活性的影响，以了解突变导致基因调控、复合物形成和功能丧失的分子基础。这些发现有助于全面了解胰岛素作用和分泌的转录控制，并合理靶向这些转录因子，以调节其活性并逆转突变的不良影响，从而潜在地治疗糖尿病。

Gene-specific transcription factors initiate transcription by specifically recognizing promoter regions of the target genes and mediating interactions with coregulators to recruit the remainder of the main transcriptional machinery. A large number of Mendelian human diseases have been linked to the mutations in genes encoding these transcription factors and in fact, a recent complete human genome analysis revealed that transcription factors represent one of the four major functional groups of proteins whose germline mutations result in various human diseases. Our long-term goal is to understand the molecular mechanisms of gene regulation by these transcription factors and the molecular basis of disease-causing mutations found in them, and this proposal focuses on diabetes. HNF1alpha and HNF4alpha play vital roles in organ development and adult homeostasis, and have been identified as culprit gene products for the monogenic dominant inherited forms of diabetes. Despite their similar physiological roles, they belong to completely different transcription factor families and possess distinctive mechanisms of gene regulation through their unique structures and interacting with different sets of coregulators. Detailed structural information on how the molecular interactions occur during the multicomplex formation is not completely known. Therefore, we propose to (1) solve the crystal structure of HNF1alpha and HNF4alpha in complex with its target DNA and other functional partners, and (2) examine the effects of diabetes-causing mutations on protein stability, DNA binding, protein-protein interaction in vitro and overall transcriptional activity in vivo to understand the molecular basis of gene regulation, complex formation and functional loss by mutations. These findings should aid overall understanding of transcription control involved in insulin action and secretion, and rational targeting of these transcription factors in order to modulate their activities and reverse the adverse effects by the mutations, thus potential treatment for diabetes.