To study glycobiology-related abnormalities in retinal degeneration, an area that is relatively unexplored

Retinal degeneration is the leading cause of irreversible blindness. Retinitis pigmentosa (RP) is a genetically heterogenous group of diseases. In the United States, approximately one in 4000 individuals is affected. RP begins with the loss of night vision due to the loss of rod photoreceptor cells. The disease progresses slowly with the loss of peripheral vision, and eventually leads to complete debilitating and irreversible blindness. The first mutation associated with human RP was identified in the gene encoding rhodopsin, the G-protein coupled receptor of rod photoreceptor cells. Mutations within the rhodopsin gene account for significant portion of RP cases. Specifically, mutations of the proline at residue 347 in rhodopsin have been linked to human RP. We are fortunate to have access to the P347S rhodopsin mutant mice. These mice represent an excellent transgenic mouse model of retinal degeneration. The P347S rhodopsin mutation is one of the best studied mutations, yet the mechanism by which the mutation causes degeneration is still unknown. One study has demonstrated that galectin-1 plays a role in degeneration of neuronal processes (1) and another study has shown that expression level of galectin-3 is elevated in retinas of patients with age-related macular degeneration. These studies in conjunction with the availibility of the P347S mutant mice have provided impetus to examine the pathogenesis of retinal degeneration in the context of the possible role of glycans and glycan-binding proteins. The time course of photoreceptor degeneration in the P347S mouse model has been carefully studied. In these mice, degeneration is barely detectable at 1 month of age, yet biochemical evidence suggests that the rod photoreceptor cells have already begun to die. At 4 months of age, approximately half of the rod photoreceptor cells have degenerated. To distinguish involvement of glycogens at the various stages of retinal degeneration, we have collected retinas of wild type and the mutant mice at four time points (1, 2, 3, and 4 months of age). This will allow us to identify the genes that target early, mid- and late stages of the retinal degeneration process. Thus we request the analysis of total 24 samples as specified below: Age Group (months) Mice No of samples at each time point 1 Wild type 3 2 Wild type 3 3 Wild type 3 4 Wild type 3 1 P347S 3 2 P347S 3 3 P347S 3 4 P347S 3 Total 24.视网膜变性是引发不可逆失明的首要病因。 色素性视网膜炎（Retinitis pigmentosa, RP）是一组遗传异质性疾病。在美国，约每4000名个体中便有1人罹患此病。 RP首发症状为夜盲，由杆状光感受器细胞丢失所致；病情进展缓慢，伴随周边视力逐步丧失，最终可导致完全致残且不可逆的失明。 首个与人类RP相关的突变于编码视紫红质（rhodopsin）的基因中被鉴定，视紫红质是杆状光感受器细胞的G蛋白偶联受体（G-protein coupled receptor）。 视紫红质基因的突变在RP病例中占比可观，其中视紫红质第347位脯氨酸残基的突变与人类RP密切相关。 我们有幸获取了P347S视紫红质突变小鼠，该模型是性能优异的视网膜变性转基因小鼠模型。 P347S视紫红质突变是研究最为深入的突变之一，但其引发视网膜变性的具体机制仍未明确。 已有研究证实半乳糖凝集素-1（galectin-1）在神经元突起变性中发挥作用，另有研究显示年龄相关性黄斑变性患者的视网膜组织中，半乳糖凝集素-3（galectin-3）的表达水平升高。 结合P347S突变小鼠的可获得性，上述研究推动我们探究聚糖（glycans）与糖结合蛋白在视网膜变性发病机制中的潜在作用。 P347S小鼠模型中光感受器变性的时间进程已被细致研究：该品系小鼠在1月龄时几乎无法检测到变性征象，但生化证据表明杆状光感受器细胞已启动死亡程序。至4月龄时，约半数杆状光感受器细胞已发生变性。 为区分聚糖在视网膜变性不同阶段的参与作用，我们分别在4个时间点（1、2、3、4月龄）收集了野生型与突变型小鼠的视网膜组织，以期鉴定靶向视网膜变性早期、中期与晚期阶段的差异表达基因。 因此我们申请对总计24份样本开展如下分析： | 月龄 | 小鼠类型 | 单时间点样本量 | | :--- | :------- | :------------- | | 1 | 野生型 | 3 | | 2 | 野生型 | 3 | | 3 | 野生型 | 3 | | 4 | 野生型 | 3 | | 1 | P347S | 3 | | 2 | P347S | 3 | | 3 | P347S | 3 | | 4 | P347S | 3 | 总计：24份样本。