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

翼螺旋核转录因子家族HNF3a和b成员在肝脏和胰腺基因调控中发挥重要作用。HNF3a基因的缺失导致一种复杂的表型与早期出生后死亡。HNF3b敲除小鼠由于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，阐明HNF3a基因敲除表型的分子基础。目前的假设是，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，我们将通过基因芯片分析来分析这些组织中的基因表达，随后通过制备过表达所鉴定基因的转基因小鼠，利用基因拯救实验来研究鉴定的靶基因。此外，鉴定的基因将作为遗传来源未知的2型糖尿病患者遗传分析的基础。第二部分的科学原理将探讨HNF3a和HNF3b依赖基因调控的分子基础，并将遵循两种假设，即HNF3a和HNF3b具有相似的功能，或者HNF3a和HNF3b通过不同的途径调控基因表达。为了回答这个问题，我们将准备一个在HNF3b基因座上表达HNF3a的“敲入”动物，以确定前者是否可以替代后者。在对这些小鼠进行表征后，研究将使用体外方法进行扩展，以分析负责辅因子募集的hnf3结构域以及哪些辅因子被两种受体同种异构体结合。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在此过程中哪些靶基因受到调控的理解。

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.