CILIA IN EYE DEVELOPMENT AND DISEASE

描述（由申请人提供）：本研究计划主要研究纤毛在光感受器形态发生中的作用。纤毛对许多组织的发育、分化和功能至关重要。在脊椎动物的眼睛中，感光细胞的感光部分，即所谓的外节，形成了高度分化的纤毛。睫状体轴突缺失时，睫状体外节不形成，光感受器丧失功能，发生变性。轻微的纤毛缺陷经常引起视色素在感光细胞中的错误定位。这是一种严重的缺陷，已知会导致感光细胞死亡。许多形式的人类失明都与纤毛功能障碍有关。肾病（NPHP）和梅克尔-格鲁伯综合征（MKS）是睫状体疾病，除其他异常外，还包括光感受器变性和失明。虽然已经确定了几个NPHP和MKS基因，但它们的蛋白质产物在细胞中的功能却知之甚少，如果有的话。我们假设NPHP和MKS蛋白参与了视色素向光感受器外段的运输。因此，它们的缺陷导致视色素定位错误和光感受器死亡。利用生化和遗传学方法，我们确定了MKS和NPHP蛋白之间的结合相互作用以及参与纤毛蛋白运输的分子复合物。在这里，我们建议进一步研究这些相互作用，并测试MKS和NPHP蛋白如何促进视蛋白在光感受器外段的运输。对人类携带NPHP和MKS缺陷的研究发现了许多导致光感受器死亡的分子损伤。然而，这些病变如何影响蛋白质功能仍然未知。我们将测试人类突变如何影响NPHP和MKS蛋白定位到纤毛并结合其伴侣的能力。结合上述实验，这些研究将揭示光感受器形态发生、功能和存活的基本机制。他们还将提供一种方法来测试人类突变对感光细胞中蛋白质功能的特定方面的影响。

DESCRIPTION (provided by applicant): This research proposal focuses on the role of cilia in photoreceptor morphogenesis. Cilia are essential for development, differentiation, and function of many tissues. In the vertebrate eye, the photosensitive part of the photoreceptor cell, the so-called outer segment, forms as a highly differentiated cilium. In the absence of ciliary axoneme, the outer segment does not form, the photoreceptor is not functional, and it degenerates. Milder cilia defects frequently cause the visual pigment mislocalization in the photoreceptor cell. This is a serious defect, known to cause photoreceptor death. Many forms of human blindness involve cilia malfunction. Nephronophthisis (NPHP) and Meckel-Gruber syndrome (MKS) are ciliary disorders that in addition to other abnormalities involve photoreceptor degeneration and blindness. Although several NPHP and MKS genes have been identified, the function of their protein products in the cell is poorly understood, if at all. We hypothesize that NPHP and MKS proteins contribute to the transport of the visual pigment to the photoreceptor outer segment. Accordingly, their defects lead to visual pigment mislocalization and photoreceptor death. Using biochemical and genetic approaches, we identified binding interactions between MKS as well as NPHP proteins and molecular complexes involved in ciliary protein transport. Here we propose to study these interactions further, and to test how MKS and NPHP proteins contribute to opsin transport in the photoreceptor outer segment. The studies of human carries of NPHP and MKS defects identified many molecular liesions that cause photoreceptor death. How do these lesions affect protein function remains, however, unknown. We will test how human mutations impact the ability of NPHP and MKS proteins to localize to cilia and to bind their partners. Together with experiments outlined above, these studies will reveal fundamental mechanisms, necessary for photoreceptor morphogenesis, function, and survival. They will also offer a way to test the impact of human mutations on specific aspects of protein function in the photoreceptor cell.