Mechanisms of ADPKD cystogenesis

 描述（由申请方提供）：常染色体显性遗传性多囊肾病（ADPKD）是一种常见的危及生命的疾病，其特征为进行性肾小管扩张、双侧形成和扩张的多个充满分隔液体的囊肿，这些囊肿逐渐压迫肾实质，从而改变肾脏结构并逐渐损害器官功能。到目前为止，ADPKD还没有治愈方法，它仍然是终末期肾病的主要原因。ADPKD发病机制复杂，尚未完全了解。这种疾病是由PKD 1或PKD 2基因的种系突变引起的，PKD 1或PKD 2基因分别编码多囊蛋白-1（PC 1）或多囊蛋白-2（PC 2）。PC 1和PC 2在各种信号通路中交叉，这些信号通路在很大程度上重叠临床表现。近年来，纤毛在肾脏发育中的重要性促使人们对参与细胞发生的不同纤毛途径进行深入研究。然而，纤毛假说本身不足以解释与多囊蛋白丢失相关的更严重的细胞遗传学表型。虽然这些早期触发因素的性质尚不清楚，但可发生独立于或先于睫状体缺损的囊肿形成事件。细胞外基质（ECM）的改变一直被认为是ADPKD上皮的一个显著特征，并且囊形成过程与整合素表达增加相关。我们以前的工作已经证明了整合素-α2β1在PC 1敲低细胞存活中的重要作用。我们最近发现，整合素β1是一个以前未认识到的囊性发病机制的关键介质。本申请的工作假设是ECM-整联蛋白-PC 1相互作用在睫状和非睫状起源的囊性途径中是重要的。该假设将在体外和体内进行B检验。具体而言，我们将通过对正常和囊性细胞中参与整合素β1活化途径的蛋白质的比较分析来确定整合素β1功能如何受到PC 1的影响，并将确定整合素β1在PC 1缺失的细胞中EGF受体途径的转运和交叉活化中的作用。为了测试整合素β1在纤毛缺陷引起的肾细胞发生中的作用，我们将分析整合素β1缺失在允许条件性缺失Pkd 1、IFT 20和IFT 88的肾囊肿遗传模型中的作用。最后，我们将研究整合素-β1在疾病进展中的功能，以及使用靶向整合素-α2β1的小分子改善囊性表型的可能性。这些研究结果将有助于了解整合素β1在ADPKD发病机制中的作用，以及不同遗传来源的囊变机制是否可能汇聚到整合素β1信号通路上。重要的是，这项工作将确定整合素途径是否可以通过药理学靶向作用来减缓ADPKD的进展。

 DESCRIPTION (provided by applicant): Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common life threatening disease characterized by progressive renal tubules dilatation, bilateral formation and expansion of multiple septate fluid-filled cysts that increasinly compress the renal parenchyma, thus altering the kidney architecture and gradually impairing organ function. To date there is no cure for ADPKD, which remains a main cause of end stage renal disease. Mechanisms underlying ADPKD pathogenesis are complex and not completely understood. The disease is caused by germline mutations in the PKD1 or PKD2 genes, which code for polycystin-1 (PC1) or polycystin-2 (PC2), respectively. PC1 and PC2 intersect in various signaling pathways that converge on largely overlapping clinical manifestations. In recent years, the importance of the cilium in renal development has prompted intense investigation of the different ciliary pathways involved in cytogenesis. However, the cilia hypothesis alone is insufficient to explain the more severe cytogenetic phenotypes associated with the loss of polycystins. Cystogenic events may occur that are independent of or preceding ciliary defects, although the nature of these early triggers remains unclear. Alteration of the extracellular matrix (ECM) has long been recognized as a distinctive feature of ADPKD epithelia, and the cystogenic process is associated with increased expression of integrins. Our previous work has shown the important role of integrin-α2β1 in the survival of PC1 knockdown cells. We recently showed that integrin-β1 is a previously unrecognized key mediator of cystic pathogenesis. The working hypothesis of this application is that ECM-Integrin-PC1 interactions are important in the cystic pathways of both ciliary and non-ciliary origin. This hypothesis will b tested both in vitro and in vivo. Specifically, we will determine how Integrin-β1 functions are affected by PC1 through the comparative analysis of the proteins that participate in the integrin-β1 activation pathway in normal and cystic cells, and will determine the role of integrin-β1 in te trafficking and cross-activation of the EGF receptor pathway in cell depleted of PC1. To test the role of integrin-β1 in renal cytogenesis from ciliary defects we will analyze the effects of the deletion of integrin-β1 in genetic models of renal cystic disease that allow the conditional deletion of Pkd1, IFT20, and IFT88. Finally, we will examine the function of integrin-β1 on disease progression and the possibility to ameliorate the cystic phenotype using a small molecule to target integrin-α2β1. The results of these studies will provide insights on the function of integrin-β1 in ADPKD pathogenesis and whether cystogenic mechanisms of different genetic origin may converge onto integrin-β1 signaling pathway. Importantly, this work will determine and whether the integrin pathway can be pharmacologically targeted to slow the progression of ADPKD.