Injury Response Mediated Pathogenesis in Renal Ciliopathies

项目摘要/摘要 初级纤毛存在于大多数肾上皮细胞上，它们的破坏会导致包囊的形成。尽管他们 临床重要性，初级肾纤毛的功能仍然知之甚少。在之前的研究中，我们 另一些研究表明，当成体纤毛装配(Ift88突变体)或功能(PKD1或PKD2)被破坏时 小鼠、囊肿会在病灶区域缓慢形成。尽管肾脏中几乎所有的上皮细胞都是突变的，但仍会发生这种情况 这些基因。关于为什么这些包囊在成体诱导的突变体中的局部位置发展的线索已经出现。 数据表明，肾脏损伤促进了囊性形成，并导致整个肾脏的囊性形成。 基于这些数据，我们认为PKD2和纤毛调节肾脏损伤和修复反应，并且PKD2和纤毛 成体诱导的突变体中的局灶性包囊是由少数经历过损伤的细胞造成的。在缺席时 在正常纤毛功能的情况下，这些细胞进入持续性适应不良修复状态(如持续性SOX9所示 表达)和向囊变的进展。虽然在Ift88和PKD2突变体中形成了囊泡，但囊性肾 随着PKD2的缺失，表型往往更加严重。然而，在双重突变体中，囊性病变类似于 较温和的Ift88突变体。我们的分析进一步表明，损伤后的炎症反应在 Ift88和PKD2突变的小鼠发生改变，并观察到有包囊形成；在PKD2突变的小鼠中，这种情况会加剧 与Ift88或Ift88/PKD2双突变体比较。总的来说，这些数据表明IFT88/cilia和PKD2 调节纤毛小管上皮和应答的非纤毛免疫细胞之间的信号活动 以启动和解决伤害反应，并且当这些信号传递时促进了包囊的形成 路径被错误地控制。这项提案的目标是定义细胞，然后是分子 局灶性和广泛性损伤所致囊肿形成的机制(S)以及IFT88/纤毛和 PKD2参与了这一过程。根据这项建议，我们将确定纤毛丢失/功能障碍是否会改变 肾脏对损伤的敏感性，并导致上皮细胞适应不良修复状态的增加。我们会 利用谱系追踪的方法来确定受损细胞的后代是否直接促成了囊肿的形成。 我们将定义新的依赖于IFT88/cilia和PKD2的细胞间信号网络，参与损伤和 纤毛受损(Ift88突变体)或纤毛功能受扰时修复过程及其如何失调 (PKD2突变体)。最后，我们将定义在PKD2突变背景中丢失Ift88的机制 通过改变这些损伤和修复信号通路来抑制囊性病变的严重性。这些数据来自 需要提出以下建议：1)阐明肾纤毛的新功能，2)确定所涉及的细胞机制 3)了解IFT88/cilia和PKD2是如何参与 调节损伤/修复反应，4)评估破坏这种损伤反应如何促进包囊形成和 5)探索Ift88和PKD2突变之间上位关系的机制。

PROJECT SUMMARY/ABSTRACT Primary cilia are present on most renal epithelial cells and their disruption leads to cyst formation. Despite their clinical importance, the function of the primary renal cilium remains poorly understood. In previous studies, we and others demonstrated that when cilia assembly (Ift88 mutant) or function (Pkd1 or Pkd2) is disrupted in adult mice, cysts form slowly in focal areas. This occurs despite nearly all epithelial cells in the kidney being mutant for these genes. A hint as to why these cysts develop in focal locations in the adult-induced mutants has emerged from data indicating that renal injury promotes cyst formation and results in cyst formation throughout the kidney. Based on these data, we propose that PKD2 and cilia regulate renal injury and repair responses and that the focal cysts in the adult-induced mutants result from a few cells that have experienced an injury. In the absence of normal cilia function, these cells enter a state of persistent maladaptive repair (as marked by persistent SOX9 expression) and progress to cystogenesis. While cysts are formed in Ift88 and Pkd2 mutants, the cystic kidney phenotype is always more severe with loss of Pkd2. In double mutants, however, the cystic pathology resembles the milder Ift88 mutant alone. Our analysis further shows that the inflammatory response following injury in the Ift88 and Pkd2 mutant mice is altered and as observed with cyst formation; it is exacerbated in Pkd2 mutants compared to Ift88 or Ift88/Pkd2 double mutants. Collectively, these data suggest that IFT88/cilia and PKD2 regulate signaling activities between the ciliated tubule epithelium and the responding non-ciliated immune cells for initiation and resolution of an injury response and that cyst formation is promoted when these signaling pathways are incorrectly controlled. The goals of this proposal are to define the cellular and then molecular mechanism(s) responsible for the focal and widespread injury-induced cyst formation and how IFT88/cilia and PKD2 are involved in this process. From this proposal, we will determine whether cilia loss/dysfunction alters the kidney's sensitivity to injury and results in an increase in the state of epithelial cell maladaptive repair. We will utilize lineage tracing approaches to determine if descendants of injured cells contribute directly to cyst formation. We will define new IFT88/cilia and PKD2-dependent intercellular signaling networks involved in the injury and repair process and how they are dysregulated when cilia are disrupted (Ift88 mutant) or cilia function is perturbed (Pkd2 mutant). Finally, we will define mechanisms by which loss of Ift88 in a Pkd2 mutant background suppresses cyst severity through changes in these injury and repair signaling pathways. The data from the proposal are needed to: 1) elucidate novel functions of the renal cilium, 2) define cellular mechanisms involved in formation of the sporadic and widespread cysts, 3) understand how IFT88/cilia and PKD2 are involved in regulating injury/repair responses, 4) assess how disrupting this injury response promotes cyst formation and expansion, and 5) explore mechanisms involved in the epistatic relationship between Ift88 and Pkd2 mutations.