THE ROLE OF COLLAGEN COL22A1 IN INTRACRANIAL ANEURYSMS AND VASCULAR STABILITY

项目摘要 颅内动脉瘤（IA）是颅内主要动脉壁的浆果或气球样缺陷 占人口的1-2%。它们通常导致蛛网膜下腔出血， 30-40%的患者死亡。目前尚无有效的治疗SAH的方法， 防止IA破裂的选项。环境和遗传因素都被归因于动脉瘤 然而，遗传因素及其潜在机制在很大程度上仍然是未知的。 我们已经确定胶原COL 22 A1突变是IA发生的潜在因素 在人类病人身上。在我们的合作者领导的家族性颅内动脉瘤研究中， 测序导致在一个高度保守的区域中鉴定出一个单核苷酸多态性（SNP）， COL 22 A1仅存在于受影响的家庭成员中。然而，COL 22 A1的生物学功能目前尚不清楚。 目前还不清楚这种突变是否是人类动脉瘤的病因。 我们建议使用斑马鱼模型来确定COL 22 A1在维持血管紧张素转换酶活性中的功能。 完整性，并确定潜在的治疗策略，将导致预防动脉瘤形成 和破裂COL 22 A1的蛋白质序列在人类和斑马鱼之间高度保守，并且其编码的蛋白质序列在人类和斑马鱼之间高度保守。 斑马鱼已经成为用于血管功能的体内分析的非常有利的模型系统， 疾病机制。我们的初步数据表明，COL 22 A1斑马鱼突变体显示增加 易发生动脉瘤并显示与人类动脉瘤相似的异常血管扩张 患者，而人突变SNP的诱导型表达导致肿瘤发生频率增加 在斑马鱼胚胎中。我们假设COL 22 A1参与调节血管完整性， COL 22 A1的突变导致颅内动脉瘤。具体目标如下： 建议：1）确定COL 22 A1在维持血管稳定性中的功能作用; 2）确定是否 COL 22 A1突变导致颅内动脉瘤; 3）进行化学筛选以发现药物 抑制COL 22 A1突变胚胎中的胚胎发育的候选物。斑马鱼COL 22 A1突变体胚胎 并分析成年人的形态和功能缺陷。人类的突变将被模拟在 通过使用CRISPR / Cas9介导的同源定向修复产生敲入等位基因， 分析IA相关的表型将使用斑马鱼COL 22 A1进行化学文库筛选 突变体，以鉴定可能补偿COL 22 A1功能缺陷的候选药物。 该项目将在体内鉴定COL 22 A1同源物的生物学功能。将进一步 确定COL 22 A1突变是否会导致IA，并确定可用于IA治疗的候选药物。 了解动脉瘤的遗传原因将使筛查能够识别风险患者，并将促进 开发新的治疗方法，可以防止颅内出血的破坏性后果。

Project Summary Intracranial aneurysms (IA) are berry- or balloon-like defects in the wall of a major intracranial artery and are present in 1-2% of the population. They commonly result in subarachnoid hemorrhage, which leads to death in 30-40% of the patients. There is currently no effective therapy to treat SAH and only limited treatment options to prevent IA rupture. Both environmental and genetic factors have been attributed to the aneurysm formation; however, the genetic factors and their underlying mechanisms are still largely unknown. We have identified mutations in collagen COL22A1 as potential contributors to the development of IAs in human patients. In the Familial Intracranial Aneurysm study, led by our collaborators, whole exome sequencing resulted in identification of a single nucleotide polymorphism (SNP) in a highly conserved region of COL22A1 present in only affected family members. However, biological function of COL22A1 is currently not known, and it is not clear if the identified mutation is causative of aneurysms in humans. We propose to use a zebrafish model to determine the function of COL22A1 in maintaining vascular integrity and to identify potential therapeutic strategies that would lead to the prevention of aneurysm formation and rupture. The protein sequence of COL22A1 is highly conserved between humans and zebrafish, and the zebrafish have emerged as a highly advantageous model system for in vivo analysis of vascular function and disease mechanisms. Our preliminary data indicate that COL22A1 zebrafish mutants display increased susceptibility to hemorrhages and show abnormal vascular dilations comparable to aneurysms in human patients, while inducible expression of the human mutant SNP results in increased frequency of hemorrhages in zebrafish embryos. We hypothesize that COL22A1 is involved in regulating vascular integrity and permeability and that mutations in COL22A1 cause intracranial aneurysms. The following specific aims are proposed: 1) Determine the functional role of COL22A1 in the maintenance of vascular stability; 2) Determine if mutations in COL22A1 cause intracranial aneurysms; 3) Perform a chemical screen to discover drug candidates that suppress hemorrhages in COL22A1 mutant embryos. Zebrafish COL22A1 mutant embryos and adults will be analyzed for morphological and functional defects. The human mutation will be modeled in zebrafish by creating a knock-in allele using a CRISPR / Cas9 mediated homology-directed repair and analyzing it for IA related phenotypes. A chemical library screen will be performed using zebrafish COL22A1 mutants to identify candidate drugs that may compensate for the deficiency in COL22A1 function. The proposed project will identify the biological function of COL22A1 homolog in vivo. It will further determine if mutations in COL22A1 cause IAs, and identify drug candidates that can be used for IA treatments. Understanding genetic causes of aneurysms will enable screening to identify patients at risk and will promote development of new treatments that can prevent devastating consequences of intracranial hemorrhages.