Role of Microphthalmia/MITF Factor in Eye Development

描述(申请人提供)：在小鼠中，小眼球相关转录因子(MITF)在眼睛的视网膜色素上皮(RPE)的发育中起着关键作用。MITF是RPE特性的决定因素之一，并有助于该组织的增殖、规范和分化。在果蝇中，dmitf\S在眼盘(形成视网膜和周围头部结构的前体组织)中表达。有趣的是，它表达在视盘上皮的周膜(PM)中，类似于视泡/视杯的假定RPE区域，(A)本身不形成视网膜，(B)与视网膜上皮并列并连续，以及(C)瞬时表达已知在RPE形成中起作用的另外两个转录因子(Pax6和OTX2)的苍蝇同源物。如图所示，dMitf控制眼盘中的增殖可以抑制视网膜的同一性，并可能有助于指定上皮的非神经部分。这些惊人的相似性强烈地表明RPE和PM细胞在进化上是相关的，一条保守的MITF遗传途径在RPE和PM的发育过程中发挥作用。基于这些原因，我们建议在果蝇模型系统中研究dmitf在眼睛发育过程中的作用(S)。 在这项拨款中提出的具体目标集中在两个主要领域：分析dmitf在眼盘发育中的作用，以及识别该通路的其他组件。通过前两个目标中提出的详细的功能丧失和功能获得的研究，我们将确定dMitf如何有助于PM的规范/分化和眼盘的正常增殖。在最后两个目标中，作为表征dMitf途径的第一步，我们建议通过酵母双杂交和遗传相互作用筛选来鉴定额外的成分。我们相信，这些方法将导致识别在苍蝇和脊椎动物的眼睛形成过程中与MITF一起发挥作用的其他保守因子。 小鼠MITF基因突变会导致小眼炎、色素沉着、骨骼和听力缺陷，RPE促进光感受器细胞在整个生命过程中的正常存活和功能，并影响视网膜神经发生和发育过程中的分层。RPE在眼睛形成和功能中的这些关键作用被大量与RPE中特定表达或丰富的基因相关的疾病以及RPE功能障碍与包括老年性黄斑变性(AMD)在内的几种眼病之间的联系所突显。

DESCRIPTION (provided by applicant): In the mouse, the Microphthalmia-related Transcription Factor (Mitf) plays a critical role in the development of the retinal pigmented epithelium (RPE) of the eye. Mitf is one of the determinants of RPE identity and contributes to the proliferation, specification and differentiation of this tissue. In the fly, dMitf \s expressed within the eye disc (the progenitor tissue that gives rise to the retina and surrounding head structures). Interestingly, it is expressed in the peripodial membrane (PM) a region of the disc epithelium that, similarly to the presumptive RPE region of the optic vesicle/cup, (a) does not itself form retina, (b) is juxtaposed to and continuous with the retinal epithelium, and (c) transiently expresses the fly homologues of two other transcription factors (Pax6 and Otx2) known to function in RPE formation. As shown here, dMitf controls proliferation in the eye disc can suppress retinal identity and may contribute to the specification of the non-neural portion of the epithelium. These striking similarities strongly suggest that RPE and PM cells are evolutionarily related and that a conserved Mitf genetic pathway functions during RPE and PM development. For these reasons, we propose to investigate the function(s) of dMitf during eye development in the Drosophila model system. The specific aims proposed in this grant focus on two main areas: The analysis of dMitf function in eye disc development and the identification of additional components of the pathway. Through the detailed loss-of-function and gain-of-function studies proposed in the first two aims, we will establish how dMitf contributes to specification/differentiation of the PM and normal proliferation of the eye disc. In the last two aims and as a first step towards characterizing the dMitf pathway, we propose to identify additional components through yeast 2-hybrid and genetic-interaction screens. We believe that these approaches will lead to the identification of additional conserved factors that function with Mitf during eye formation in fly and vertebrates. Mutations in the mouse Mitf locus cause microphthalmia, pigmentation, bone and hearing defects and the RPE promotes proper survival and function of photoreceptor cells throughout life as well as influences retinal neurogenesis and lamination during development. These critical roles of the RPE in eye formation and function are highlighted by the significant number of diseases associated with genes specifically expressed or enriched in the RPE as well as by the link between RPE dysfunction and several eye diseases including age-related macular degeneration (AMD).