Role of Microphthalmia/MITF Factor in Eye Development

描述（由申请方提供）：在小鼠中，小眼症相关转录因子（Mitf）在眼睛视网膜色素上皮（RPE）的发育中起关键作用。Mitf是RPE身份的决定因素之一，并有助于该组织的增殖、特化和分化。在果蝇中，dMitf在眼盘（产生视网膜和周围头部结构的祖组织）内表达。有趣的是，它在周足膜（PM）中表达，该区域是盘上皮的一个区域，类似于视泡/视杯的假定RPE区域，（a）本身不形成视网膜，（B）与视网膜上皮并置并连续，以及（c）瞬时表达已知在RPE形成中起作用的两种其他转录因子（Pax 6和Otx 2）的蝇同源物。如图所示，dMitf控制视盘中的增殖，可以抑制视网膜特性，并可能有助于上皮的非神经部分的特化。这些惊人的相似性强烈表明，RPE和PM细胞是进化相关的，并且在RPE和PM发育过程中保守的Mitf遗传途径起作用。基于这些原因，我们建议在果蝇模型系统中研究dMitf在眼发育过程中的功能。 该补助金中提出的具体目标集中在两个主要领域：dMitf在眼盘发育中的功能分析和途径其他成分的鉴定。通过前两个目标中提出的详细的功能丧失和功能获得研究，我们将确定dMitf如何有助于PM的规格/分化和眼盘的正常增殖。在最后两个目标，并作为表征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确定其他成分。我们相信，这些方法将有助于识别出在苍蝇和脊椎动物眼睛形成过程中与Mitf一起发挥作用的其他保守因子。 小鼠Mitf基因座中的突变导致小眼症、色素沉着、骨和听力缺陷，并且RPE在整个生命中促进感光细胞的适当存活和功能，以及在发育期间影响视网膜神经发生和分层。RPE在眼睛形成和功能中的这些关键作用通过与RPE中特异性表达或富集的基因相关的大量疾病以及通过RPE功能障碍与包括年龄相关性黄斑变性（AMD）的几种眼病之间的联系而突出。

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).