GENETIC ANALYSIS OF PHOTORECEPTOR DIFFERENTIATION

描述(申请人提供)：光感受器是高度专门化的视网膜感光细胞，对视觉感知至关重要。由于遗传原因导致的人眼光感受器的丧失是一种常见的失明原因。虽然对光感受器细胞的研究投入了大量的努力，但对其分化和功能的一些基本方面仍然知之甚少。特别是，导致复杂的光感受器形态组装的分子机制实际上仍然未知。这些机制的缺陷经常导致光感受器死亡，并导致人类失明。 要深入了解人眼光感受器退化的遗传原因，一个非常有成效的方法是研究光感受器丧失的动物模型。斑马鱼是用于研究视网膜疾病遗传原因的主要动物模型之一。利用斑马鱼的突变方法，我们已经鉴定和表征了几个导致光感受器死亡的突变。MOK基因的突变似乎会影响光感受器核的定位，并导致光感受器细胞的特别早期丢失。我们已经确定了MOK基因缺陷的分子性质，并确定它影响细胞内运动复合体的活性。除了其他功能外，这种复合体还可以调节细胞核的位置。这些研究揭示了分子马达在脊椎动物光感受器分化和存活中的作用。 我们正计划利用现有的化学诱导的突变等位基因和反向遗传反义干扰策略来表征MOK运动复合体成分在光感受器分化和存活中的作用。特别是，我们想要集中在MOK马达在细胞核定位和与Bardet-Biedl综合征(BBS)相关的蛋白质的亚细胞定位中的作用，BBS是一种人类疾病，导致光感受器细胞丧失、肾脏缺陷、肥胖和多指畸形。我们的初步研究表明，mok基因对于BBS多肽的正确亚细胞定位是必要的。我们将在斑马鱼胚胎中使用体外生化方法以及体内遗传测试来研究MOK和BBS蛋白的相互作用。这些研究将深入了解光感受器退化的机制及其与人类光感受器疾病的关系。

DESCRIPTION (provided by applicant): Photoreceptors are highly specialized light-sensitive cells of the retina, essential for visual perception. The loss of photoreceptors in the human eye due to genetic causes is a frequent cause of blindness. Although a lot of effort has been devoted to the studies of the photoreceptor cell, some essential aspects of its differentiaton and function remain poorly understood. In particular, the molecular mechanisms, which lead to the assembly of the sophisticated photoreceptor morphology remain virtually unknown. Defects of these mechanisms frequently cause photoreceptor death and lead to blindness in humans. A very productive way to gain insight into the genetic causes of photoreceptor degeneration in the human eye is to study animal models of photoreceptor loss. The zebrafish is one of the leading animal models used to study the genetic causes of retinal disease. Using a mutagenesis approach in zebrafish, we have identified and characterized several mutations that lead to photoreceptor death. A mutation in the mok gene appears to affect the positioning of the photoreceptor nucleus and causes a particularly early loss of photoreceptor cells. We have characterized the molecular nature of the mok genetic defect and determined that it affects the activity of an intracellular motor complex. This complex, among other functions, is known to regulate the positioning of the cell nucleus. These studies reveal the role of molecular motors in vertebrate photoreceptor differentiation and survival. We are planning to characterize the role of the mok motor complex components in photoreceptor differentiation and survival using both the existing chemically-induced mutant alleles as well as reverse genetic antisense interference strategies. In particular, we would like to focus on the role of the mok motor in the positioning of the cell nucleus and in the subcellular localization of proteins associated with the Bardet-Biedl syndrome (BBS), a human disorder leading to the loss of photoreceptor cells, kidney defects, obesity, and polydactyly. Our preliminary studies indicate that the mok gene is necessary for the proper subcellular localization of BBS polypeptides. We will investigate the interactions of Mok and BBS proteins using in vitro biochemical approaches as well as in vivo genetic tests in the zebrafish embryo. These studies will provide insight into the mechanisms of photoreceptor degeneration and their relatedness to human photoreceptor diseases.