Mechanism of APBB2 contributions to glaucoma

摘要 青光眼是一组与年龄相关的神经退行性疾病，其特征是视网膜神经节细胞的丢失 和它们的轴突因为RGC是有丝分裂后的神经元，它们的损失是永久性的，并引起逐渐的神经元损伤。 导致不可逆转的失明。不幸的是，青光眼的表现方式损害了我们 社会更广泛，它不成比例地影响某些种族群体。青光眼是一个更严重的问题 非裔美国人比白种人多虽然社会经济因素往往造成这种差距， 很大一部分是生物学的，是由种族群体之间的基因组差异驱动的。最近的一个突破 指出APBB2是非裔美国人青光眼的核心。大型全基因组关联研究（GWAS） 发现APBB2基因的一个单核苷酸多态性位点rs59892895，具有全基因组显著性（P = 2x10 - 8; 比值比= 1.33），并在其他队列中成功复制了这一发现。在APBB2中发现了一个变异体， 基因是非洲人后裔青光眼的重要原因。ABPP2编码一个胞质衔接子 具有多个蛋白质-蛋白质相互作用结构域的蛋白质。值得注意的是，高风险等位基因存在于 大约21%的非洲裔美国人，显然没有白人。我们的团队为 APBB2作为对非裔美国人青光眼重要的基因的这一发现， 在我们的初步数据中，已经提出了一个假设，即APBB2的过度表达是导致疾病的原因。 机制为了验证这一新的假设，我们最近生成了一个小鼠模型， 过表达Apbb2的纯C57BL/6J遗传背景。该菌株是由美国密歇根大学 爱荷华州基因组编辑设施，并具有全长小鼠Apbb2（转录变体1）的控制下， 普遍存在的启动子（CAG），并且包括连接到N-末端的6His/3XFlag（缩写为B6 - 3XFlag）。 Tg（Apbb2）。该提案的实验利用这种新菌株作为中心资源来完成 重要的是，但风险有点高，通过操作测试Apbb2的过度表达会促进青光眼。在 具体目标1，我们建议测试Apbb2随时间推移的解剖学和生理学后果 在小鼠中过度表达。该目标还将完成B6-Tg（Apbb2）菌株的全面表征。 具体目标2将从分子角度研究APBB2，确定视网膜APBB2结合伴侣， 将指导未来的机制和候选人驱动的遗传实验。

Abstract Glaucoma is a group of age-related neurodegenerative diseases characterized by loss of retinal ganglion cells and their axons. Because RGCs are post-mitotic neurons, their loss is permanent and causes a gradual decline leading toward irreversible blindness. Unfortunately, glaucoma manifests in a way that damages US society more broadly—it disproportionately affects certain racial groups. Glaucoma is a worse problem amongst African Americans than Caucasians. Though socioeconomic factors often contribute to this disparity, a large part is biological and driven by genomic differences between racial groups. A recent breakthrough points to APBB2 as central to glaucoma in African Americans. A large genome-wide association study (GWAS) has found a single nucleotide polymorphism in APBB2 (rs59892895) with genome-wide significance (P=2x10-8; Odds ratio=1.33), and successfully replicated the finding in additional cohorts. identified a variant in the APBB2 gene as an important cause of glaucoma in people of African descent. ABPP2 encodes a cytoplasmic adaptor protein with multiple protein-protein interaction domains. Remarkably, the high-risk allele is present in approximately 21% of African Americans and apparently absent from Caucasians. Our team has contributed to this discovery of APBB2 as a gene of importance to glaucoma in African Americans, and as additionally shown in our Preliminary Data, have developed a hypothesis that overexpression of APBB2 is the disease-causing mechanism. To test this new hypothesis, we recently generated and now have in hand, a mouse model on a pure C57BL/6J genetic background that is overexpressing Apbb2. The strain was created by the University of Iowa Genome Editing Facility and features a full-length mouse Apbb2 (transcript variant 1) under control of a ubiquitous promotor (CAG) and includes a 6His/3XFlag attached to the N-terminus (abbreviated as B6- Tg(Apbb2). The experiments of this proposal utilize this new strain as a central resource to complete the important, but somewhat high risk, test via manipulation that over-expression of Apbb2 promotes glaucoma. In Specific Aim 1, we propose to test the anatomical and physiological consequences over time of Apbb2 overexpression in mice. This Aim will also complete a thorough characterization of the B6-Tg(Apbb2) strain. Specific Aim 2 will study APBB2 from a molecular perspective, identifying retinal APBB2 binding partners that will guide future mechanistic and candidate-driven genetic experiments.