COBRE: PHOTORECEPTOR PROTECTION IN MOUSE MODEL FOR USHER SYNDROME

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。在有丝分裂后的感光细胞中，当视网膜中的代谢活动增加时，细胞死亡显著增加。这与光感受器中线粒体的高焦点浓度和脉络膜毛细血管的非常高的血液供应一起表明，光感受器细胞的能量供应可能很少。光感受器、M 11 er细胞和视网膜色素上皮之间复杂的相互关系增加了其他细胞类型的失败容易导致次级光感受器细胞损失的脆弱性。似乎感光细胞生活在刀刃上，相对温和的损伤可以显著增加细胞死亡的可能性。另一方面，对细胞的相对适度的益处可能会降低细胞死亡的机会，足以对视力产生重要的临床影响。Usher综合征是一组具有常染色体隐性遗传、先天性听力损失和视网膜色素变性（一种影响感光细胞并导致失明的遗传性疾病）发展的疾病。rd 5/rd 5小鼠已被鉴定为Usher综合征的动物模型，连锁图谱表明与位于人11号染色体p15上的Usher I型同源。生长因子如色素上皮衍生因子（PEDF）和碱性成纤维细胞生长因子（bFGF）和小分子如苯基-N-叔丁基硝酮（PBN）已显示在大鼠模型和培养物中保护光感受器免于变性。然而，PEDF和PBN保护光感受器的机制仍然未知。由于对Usher I型疾病知之甚少，并且目前还没有针对这种疾病的治疗方法，因此了解rd 5/rd 5小鼠中的光感受器变性是否也可以通过生长因子或小分子延迟或预防将是重要的。本提案的总体目标是探索生长因子和小分子在rd 5/rd 5小鼠感光细胞保护中的作用。将通过测量外核层的厚度在组织学上评价保护，并通过视网膜电图在功能上评价保护。蛋白质组学和DNA微阵列将用于鉴定纯合子（rd 5/rd 5）和正常杂合子（rd 5/+）小鼠（有和无治疗）之间差异表达的基因和蛋白质。Western和北方印迹分析将用于定量表达，免疫组织化学和原位杂交将用于定位表达。我们的任何实验方案，防止光感受器在这只老鼠的损失，将是非常相关的人类与Ushers和可能的其他类型的遗传性视网膜疾病的治疗。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In post-mitotic photoreceptor cells, there is a significant increase in cell death when metabolic activity in the retina increases. This, together with the high focal concentrations of mitochondria in photoreceptors and the very high blood supply to the choriocapillaris, suggests that there may be very little reserve in the energy supply to photoreceptor cells. The complex inter-relationships between photoreceptors, M¿11er cells and retinal pigment epithelium add to the vulnerability in that failure of other cell types readily leads to secondary photoreceptor cell loss. It seems possible that photoreceptor cells live on a knife's edge, and that relatively mild insults can significantly increase the probability of cell death. On the other hand, a relatively modest benefit to the cell may reduce the chances of cell death sufficiently to have an important clinical impact on vision. Usher syndrome is a group of diseases with autosomal recessive inheritance, congenital hearing loss, and the development of retinitis pigmentosa, a hereditary disease that affects photoreceptor cells and causes blindness. The rd5/rd5 mouse has been identified as an animal model for Usher syndrome and linkage mapping suggests homology to Usher type I located on human chromosome 11 at p15. Growth factors such as pigment epithelium-derived factor (PEDF) and basic fibroblast growth factor (bFGF)and small molecules such as phenyI-N-tert-butylnitrone (PBN) have been shown to protect photoreceptors from degeneration in rat model and in culture. However, the mechanism(s) by which PEDF and PBN protect photoreceptors remains unknown. Because little is known about Usher Type I disease and currently, no treatment exists for such disease, it would be important to know whether photoreceptor degeneration in rd5/rd5 mouse can also be delayed or prevented by growth factors or small molecules. The overall goal of this proposal is to explore the role of growth factors and small molecules in photoreceptor protection in rd5/rd5 mice. The protection will be evaluated histologically by measuring the thickness of the outer nuclear layer and functionally by electroretinography. Proteomics and DNA-microarrays will be used to identify genes and proteins differentially expressed between homozygous (rd5/rd5) and normal heterozygous (rd5/+) mice with and without treatments. Western and Northern blot analysis will be used to quantitate the expression, and immunohistochemistry and in situ hybridization will be used to localize the expression. Any of our experimental regimes, which prevent the loss of photoreceptors in this mouse, would be extremely relevant to the therapeutic treatment of humans with Ushers and possibly other types of inherited retinal disorders.