Genetics of Endocytic Trafficking in the Eye

描述（由申请人提供）：细胞持续摄取营养物质和信号分子。内化的蛋白质从质膜经过早期的内体、多泡体（MVB），最后到达溶酶体。在特化的后生动物细胞中，内体还充当蛋白质运输至溶酶体相关细胞器的中间体，所述溶酶体相关细胞器包括皮肤和眼睛中的黑素体、II型肺细胞中的板层体、血小板中的致密颗粒和细胞毒性T细胞中的溶解颗粒。干扰该途径中的运输的遗传缺陷是包括Chediak-Higashi和Hermansky-Pudlak综合征（HPS）在内的几种疾病的根本原因。果蝇复眼是一个很好的模型系统，用于内吞运输的遗传分析。这一过程所必需的许多基因突变已被确定为眼睛颜色突变，因为它们干扰了生物合成货物向色素颗粒的传递。在发育中的眼中，配体Boss和Delta提供了直接测定来分析基因对体内内吞运输的贡献。该建议旨在利用果蝇眼睛的特征对多细胞生物中的内吞运输进行遗传解剖。在目标1中，我们计划解剖的具体作用，每两个替代Vps-C复合物在调节内吞运输，和溶酶体相关的细胞器的生物发生。为此，我们将使用两对替代亚基Car/dVps 33 A、dVps 16 A、dVpsSSB和dVps 16 B的功能丧失模型。在目标2中，我们将确定内吞运输中需要red的特定步骤，red是在大规模筛查HPS相关突变中发现的基因之一。在目标3中，我们将剖析果蝇腺泡在膜运输和染色质凝聚中的双重功能是如何被调节的。在目的4中，我们将分析dPallidin在将货物递送到溶酶体相关细胞器中的功能。我们已经产生了dpallidin无效等位基因来测试两种替代模型，这表明Pallidin可以调节早期内体融合或退出MVB。

DESCRIPTION (provided by applicant): Cells continuously take up nutrients and signaling molecules. Internalized proteins destined for degradation are routed from the plasma membrane through early endosomes, multivesicular bodies (MVBs), and finally to lysosomes. In specialized metazoan cells, endosomes also serve as intermediates in protein trafficking to lysosome-related organelles including melanosomes in the skin and eye, lamellar bodies in type II lung cells, dense granules in platelets, and lytic granules in cytotoxic T-cells. Genetic defects that interfere with trafficking in this pathway are the underlying causes of several disorders including Chediak-Higashi and Hermansky-Pudlak syndrome (HPS). The Drosophila compound eye is an excellent model system for a genetic analysis of endocytic trafficking. Mutations in many genes necessary for this process have been identified as eye color mutations because they interfere with the delivery of biosynthetic cargo to pigment granules. In the developing eye, the ligands Boss and Delta provide direct assays to analyze the contribution of genes to endocytic trafficking in vivo. This proposal is aimed at exploiting the features of the Drosophila eye for a genetic dissection of endocytic trafficking in multicellular organisms. In Aim 1, we plan to dissect the specific roles each of two alternative Vps-C complexes have in regulating endocytic trafficking, and the biogenesis of lysosome-related organelles. For this purpose, we will use loss-of-function models of the two pairs of alternative subunits Car/dVps33A, dVps16A, dVpsSSB, and dVps16B. In Aim 2, we will determine the specific step in endocytic trafficking that requires red, one of the genes discovered in a large-scale screen for HPS-related mutations. In Aim 3, we will dissect how the dual functions of Drosophila Acinus in membrane trafficking and chromatin condensation are regulated. In Aim 4, we will analyze the function of dPallidin in the delivery of cargo to lysosome-related organelles. We have generated a dpallidin null allele to test two alternative models that suggest that Pallidin may regulate early endosomal fusion or exit from MVBs.