Die Rolle der Transkriptionsfaktoren HNF3alpha und HNF3beta in der Genregulation von Leber, Pankreas und Hypothalamus

HNF3a和b是有翼螺旋核转录因子家族的成员，在肝脏和胰腺的基因调控中起着重要的作用。HNF3a基因缺失导致具有早期出生后死亡的复杂表型。HNF3b基因敲除的小鼠因胚胎发育缺陷而在出生前死亡。该项目将使用两种方法重点研究这两种受体的生物学功能。首先，将阐明HNF3a基因敲除表型的分子基础。工作假设是，观察到的表型是由于肝脏、肠道、下丘脑或胰腺基因的遗传失调。为了回答这个问题，将通过基因芯片分析这些组织中的基因表达，然后通过制备过度表达已识别基因的转基因小鼠，使用遗传拯救实验来研究已识别的目标基因。此外，识别出的基因将被用作遗传来源不明的II型糖尿病患者的遗传分析的基础。第二部分的科学基础将涉及HNF3a和HNF3b依赖的基因调控的分子基础，其中将遵循两个假设，即HNF3a和HNF3b具有相似的功能，或HNF3a和HNF3b通过不同的途径调控基因表达。为了回答这个问题，将准备一个在HNF3b基因位点表达HNF3a的“敲入”动物，以确定前者是否可以替代后者。在确定了这些小鼠的特征后，这项研究将利用体外方法来分析HNF3结构域，这些结构域负责辅因子招募，哪些辅因子被两种受体亚型结合。这两种方法的结合将促进我们对HNF3a和b如何赋予其基因调控活性以及哪些靶基因在这一过程中受到调控的理解。

HNF3a and b members of the winged helix nuclear transcription factor family play an important role in liver and pancreas gene regulation. Deletion of the HNF3a gene results in a complex phenotype with early postnatal mortality. HNF3b knock out mice die before birth due to a defect in embryonic development. The project will focus on the biological function of both receptors using two approaches. First, the molecular basis of the HNF3a knock out phenotype will be elucidated. The working hypothesis is that the phenotype observed is due to a genetic dysregulation of either liver, gut, hypothalamus or pancreatic genes. To answer this question, gene expression will be analyzed in these tissues by genechip analysis and identified target genes will subsequently be studied using genetic rescue experiments by preparing transgenic mice overexpressing the identified genes. In addition the identified genes will be used as basis for genetic analysis of patients with type II diabetes of unknown genetic origin. The scientific rationale of the second part will address the molecular basis of HNF3a and HNF3b dependent gene regulation where two hypotheses will be followed, i.e., HNF3a and HNF3b have similar functions, or HNF3a and HNF3b regulate gene expression via different pathways. To answer this question a "knock-in" animal will be prepared which exprexsses HNF3a in the locus of HNF3b to determine whether the first can substitute for the latter. After characterisation of these mice the studies will be extended using in vitro approaches to analyze HNF3-domains that are responsible for cofactor recruitment and which cofactors are bound by the two receptor isoforms. The combination of both approaches will advance our understanding of how HNF3a and b confer their gene regulatory activity and which target genes are regulated in this process.