Pathologic Mechanisms of Polycystic Kidney Disease

常染色体显性遗传性多囊肾病(ADPKD)是由编码基因突变引起的 多囊蛋白-1和/或多囊蛋白-2，但导致上皮细胞黏附连接中断和 受损的β-连环蛋白信号通路。我们的数据显示了多蛋白复合体中的多囊蛋白 粘合连接元件。这些复合体与血浆膜微域相关。 含有结构脂筏蛋白Flotillin-2，但不包含类似的含有小窝蛋白的微域。 粘着连接复合体的破坏与LAR家族受体酪氨酸的下调有关 磷酸酶和复合体中蛋白质的过度磷酸化。由于粘连连接提供了 通过与肌动蛋白细胞骨架的连接以及这种连接对上皮片的结构稳定性 在ADPKD中受到损害，这些变化可能有助于疾病的病理。我们 假设Flotillin-2膜微区代表多囊蛋白被激活和 与信号分子协同作用，实现稳定的细胞间黏附。因此，当多囊蛋白-1 功能突变或缺失，启动细胞黏附的信号发生改变，并在肾囊变中发生变化 潜在的结果。本方案中的实验将阐明组织和功能 与Flotillin-2膜微域相关的含多囊蛋白多蛋白复合体 探索共定位的酪氨酸激酶和磷酸酶并监测Flotillin-2的作用 筏向肌动蛋白重塑、膜剥离和稳定的细胞-细胞黏附。圆满完成 拟议的实验将提供有关事件引导的时间序列的新的机械性信息 从多囊蛋白-1激活到稳定E-钙粘附素介导的黏附。这些机械的洞察力 有望对设计治疗干预措施有用，特别是那些利用激酶的治疗干预措施 抑制剂。

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is caused by mutations in the genes encoding polycystin-1 and/or polycystin-2, but results in epithelial cells with disrupted adherensjunctions and compromised beta-catenin signaling pathways. Our data showthe polycystins in a multiprotein complex with adherens junction components. The complexes are associated with plasma membranemicrodomains containing the structural lipid raft protein flotillin-2, but not similar microdomains containing caveolin. Disruption of the adherens junction complexes is linked to down regulation of LAR family receptortyrosine phosphatases and hyperphosphorylation of the proteins in the complex. Since adherens junctions provide structural stability to the epithelial sheet through connections to the actin cytoskeleton, and such connections are compromised in ADPKD, these alterations are likely to contribute to the disease pathology. We hypothesize that flotillin-2 membrane microdomains represent sites wherethe polycystins are activated and cooperate with signaling molecules to bring about stable cell-cell adhesion. Consequently,when polycystin-1 function is mutant or absent, the signaling to initiate cell adhesionis altered and changes in renalcystogenic potential result. The experiments in this proposalwill elucidate the organization and function of the polycystin-containing multiprotein complexes associated with the flotillin-2 membranemicrodomainsby probing for colocalized tyrosine kinases and phosphatases and by monitoringthe contribution of flotillin-2 rafts to actin remodeling, membranetrafficking and stable cell-cell adhesion. Successfulcompletion of the proposed experiments will provide new, mechanistic information on the temporal sequence of eventsleading from polycystin-1activation to the stabilization of E-cadherin mediated adhesion. These mechanistic insights are expected to be useful for designing therapeutic interventions, particularly those that make use of kinase inhibitors.