Transcriptional Control of the Mouse aA-crystallin locus

描述（由申请人提供）：本研究项目的长期目标是阐明透镜中A-晶状体蛋白（Cryaa）基因表达所必需的分子机制，并阐明遵循类似基因调控原则的一般透镜调控机制。Cryaa表达的缺失或突变型A-晶状体蛋白的表达与透镜透明度不相容，并导致透镜混浊。受损的透镜透明度导致白内障形成，这是一种透镜疾病， 全世界的失明病例。我们现在已经确定了一个“核心”基因调控网络（GRN），由Pax 6，c-Maf和晶体蛋白基因，这是负责晶状体特异性表达的所有晶体蛋白基因。通过鉴定c-Maf和Cryaa基因中的两个FGF反应区域，我们现在可以将FGF信号传导（一种关键的透镜分化信号传导途径）与晶状体蛋白基因表达联系起来。此外，FGF 2刺激靶向c-Maf的3 '-UTR的一小组microRNA的表达。这些数据表明，c-Maf的表达是在正反馈和负反馈FGF依赖性控制下。组织特异性GRNs的一个标志是它们作为“转录工厂”在透镜纤维细胞核的3D结构内的空间定位。该提议将（1）确定FGF响应性c-Maf启动子和Cryaa远端增强子DCR 1的分子功能，随后在全基因组范围内鉴定透镜中的全局FGF调节网络，（2）通过FGF 2依赖性miR建立c-Maf的转录后调节，以及（3）检查染色质结构在分化的透镜纤维细胞核中的动态变化，并鉴定包括Cryaa在内的转录因子基因座这些数据将为理解通过FGF信号传导、特异性DNA结合转录因子的作用、调节性miR及其靶基因以及透镜纤维细胞染色质的三维组织来实现透镜纤维细胞分化的分子基础奠定基础。

DESCRIPTION (provided by applicant): The long-term goal of this research program is to elucidate those molecular mechanisms that are essential for ¿A-crystallin (Cryaa) gene expression in the lens, and to unravel general lens regulatory mechanisms that follow similar principles of gene regulation. A loss of Cryaa expression or expression of mutant ¿A-crystallin proteins is not compatible with lens transparency and results in lens opacification. Compromised lens transparency leads to cataract formation, a disease of the lens responsible for nearly half of the cases of blindness worldwide. We have now identified a "core" gene regulatory network (GRN), comprised of Pax6, c-Maf and crystallin genes, which is responsible for lens-specific expression of all crystallin genes. Through the identification of two FGF-responsive regions in c-Maf and Cryaa genes, we can now link FGF signaling, a key lens differentiation signal transduction pathway, with crystallin gene expression. In addition, FGF2 stimulates expression of a small group of microRNAs that targets 3'-UTR of c-Maf. These data suggest that c-Maf expression is underbpositive and negative-feedback FGF- dependent control. A hallmark of tissue-specific GRNs is their spatial localization as "transcriptional factories" within the 3D-structure of lens fiber cell nuclei. This proposal will (1) Determine the molecular functions of th FGF-responsive c-Maf promoter and Cryaa distal enhancer DCR1 followed by genome- wide identification of global FGF-regulated networks in the lens, (2) Establish posttranscriptional regulation of c-Maf through FGF2-dependent miRs, and (3) Examine dynamic changes of chromatin structure in differentiating lens fiber cell nuclei and to identify transcriptional factoies that include the Cryaa locus. These data will lay the foundation for understanding the molecular basis of lens fiber cell differentiation through FGF signaling, action of specific DNA-binding transcription factors, modulatory miRs and their target genes, and 3D-organization of lens fiber cell chromatin.