Injury Response Mediated Pathogenesis in Renal Ciliopathies

项目总结/摘要 初级纤毛存在于大多数肾上皮细胞上，它们的破坏导致囊肿形成。尽管他们 尽管原发性肾纤毛的功能具有重要的临床意义，但仍知之甚少。在以前的研究中，我们 和其他人证明，当成年人纤毛组装（Ift 88突变体）或功能（Pkd 1或Pkd 2）被破坏时， 在小鼠中，囊肿在病灶区域缓慢形成。尽管肾脏中几乎所有的上皮细胞都发生了突变， 对于这些基因。一个提示，为什么这些囊肿发展的焦点位置，在成人诱导的突变已经出现 数据表明肾损伤促进囊肿形成并导致整个肾脏的囊肿形成。 基于这些数据，我们提出PKD 2和纤毛调节肾损伤和修复反应， 成体诱导的突变体中的局灶性囊肿是由经历损伤的少数细胞引起的。在没有 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（以持续性SOX 9为标志 表达）并进展为囊形成。虽然在Ift 88和Pkd 2突变体中形成囊肿，但囊性肾 表型总是更严重的Pkd 2的损失。然而，在双突变体中， 更温和的Ift 88突变体。我们的分析进一步表明，损伤后的炎症反应， Ift 88和Pkd 2突变小鼠发生改变，并观察到囊肿形成;在Pkd 2突变体中加重 与Ift 88或Ift 88/Pkd 2双突变体相比。总的来说，这些数据表明，IFT 88/纤毛和PKD 2 调节纤毛小管上皮细胞和响应的非纤毛免疫细胞之间的信号传导活动 对于损伤反应的起始和消退，并且当这些信号传导时促进囊肿形成， 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 负责局灶性和广泛性损伤诱导的囊肿形成的机制以及IFT 88/纤毛和 PKD 2参与了这一过程。从这个提议中，我们将确定纤毛损失/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。我们将 利用谱系追踪方法来确定受损细胞的后代是否直接促成囊肿形成。 我们将定义参与损伤的新的IFT 88/纤毛和PKD 2依赖性细胞间信号传导网络， 修复过程以及当纤毛被破坏（Ift 88突变体）或纤毛功能受到干扰时它们如何失调 (Pkd2突变体）。最后，我们将定义在Pkd 2突变背景下Ift 88缺失的机制。 通过改变这些损伤和修复信号通路来抑制囊肿的严重性。的数据 需要提出以下建议：1）阐明肾纤毛的新功能，2）确定涉及的细胞机制 在形成散发性和广泛的囊肿，3）了解IFT 88/纤毛和PKD 2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囊肿形成， 5）探索Ift 88和Pkd 2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.