Transcriptional Control of the Mouse aA-crystallin locus

描述(申请人提供)：这项研究计划的长期目标是阐明晶状体中A-晶体蛋白(CryaA)基因表达所必需的那些分子机制，并揭示遵循类似基因调控原理的一般晶状体调控机制。CryaA表达的缺失或突变型A-晶状体蛋白的表达与晶状体透明度不相容，并导致晶状体混浊。晶状体透明度受损会导致白内障的形成，这是一种导致近一半晶状体疾病的疾病 世界范围内的失明病例。我们现在已经确定了一个由Pax6、c-Maf和晶体蛋白基因组成的“核心”基因调控网络(GRN)，它负责所有晶体蛋白基因的特异性表达。通过鉴定c-Maf和CryaA基因中的两个成纤维细胞生长因子反应区，我们现在可以将晶状体分化信号转导途径中的成纤维细胞生长因子信号与晶状体蛋白基因的表达联系起来。此外，FGF2还刺激了一小群针对c-Maf的3‘-UTR微RNA的表达。这些数据表明，c-Maf的表达是低正反馈和负反馈的成纤维细胞生长因子依赖的控制。组织特异性GRN的一个标志是它们在晶状体纤维细胞核的3D结构中作为“转录工厂”的空间定位。这一建议将(1)确定TH-FGFs反应的c-Maf启动子和CryaA远端增强子DCR1的分子功能，然后在全基因组范围内鉴定晶状体中由FGF2调控的全球网络；(2)通过依赖FGF2的miRs建立c-Maf的转录后调控；(3)检测晶状体纤维细胞核分化过程中染色质结构的动态变化，并确定包括CryaA基因在内的转录因子。这些结果将为进一步了解成纤维细胞生长因子信号转导、特异的DNA结合转录因子、调控miRs及其靶基因的作用以及晶状体纤维细胞染色质的三维结构等分子基础奠定基础。

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.