The role of DNA damage response signaling in chronic kidney disease

描述（由申请人提供）：DNA损伤反应信号在慢性肾脏疾病中的作用。肾病（NPHP）是一种常染色体隐性慢性肾脏疾病（CKD），以小管间质纤维化、小管基底膜破裂和肾囊肿为特征。肾纤维化是终末期肾病的主要决定因素，目前尚无有效的治疗方法。最近的研究已经确定NPHP是一种“纤毛病”，由基因突变引起，其蛋白质定位于中心体和/或原纤毛，并为NPHP相关纤毛病（NPHP- rc）产生了统一的致病概念。尽管在超过30个基因中发现了导致NPHP-RC的突变，但对该疾病的分子机制知之甚少。最近，通过全外显子组重测序，我参与了3个新基因CEP164、FAN1和SDCCAG8的鉴定，这些基因在NPHP-RC发生突变时导致肾脏变性/纤维化。令人惊讶的是，中心体蛋白CEP164和SDCCAG8也定位于细胞核，它们的失活导致DNA损伤反应（DDR）信号通路受损，并伴有细胞周期缺陷。因此，CEP164和SDCCAG8与FAN1（一种已知的DNA损伤修复蛋白）一起，将DDR信号缺陷作为NPHP-RC的一种新的病理机制。我假设NPHP-RC的肾变性/纤维化是由DNA损伤反应途径的缺陷引起的。为了验证这一假设，我将(1)使用Cep164和Sdccag8肾纤维化小鼠模型研究“纤毛病蛋白”在调节DNA损伤反应途径中的作用；(2)对影响和抵消NPHP-RC发病机制的小分子进行高通量筛选；(3)研究了CEP164和SDCCAG8在中心体和细胞核的双重定位之间的功能和调控。该研究的完成将提供(1)对纤毛病的病理机制的新见解；(2)可用于治疗NPHP-RC和肾纤维化的新化合物；(3)研究耐多药相关疾病的新动物模型。本K99/R00申请的目的是利用新生成的动物模型来研究NPHP-RC的分子机制。这将有助于我的研究生涯过渡到一个独立的调查员的位置。该奖项的培训（K99）阶段将由霍华德休斯医学研究所研究员、人类遗传学和儿科肾脏疾病领域国际公认的领导者Friedhelm Hildebrandt博士指导。2013年3月，我将搬到波士顿儿童医院(BCH)/哈佛医学院（HMS），与Hildebrandt博士的实验室一起工作。我的长期职业目标是成为肾脏研究领域的独立研究者，专注于肾脏疾病的动物模型。BCH/HMS有几个合作研究小组致力于肾脏发育和疾病，为我的培训和职业发展提供了理想的环境。

DESCRIPTION (provided by applicant): The role of DNA damage response signaling in chronic kidney disease. Nephronophthisis (NPHP) is an autosomal recessive chronic kidney disease (CKD), characterized by tubulointerstitial fibrosis, tubular basement membrane disruption and kidney cysts. Renal fibrosis is the primary determinant of end-stage kidney disease, with no effective therapy available today. Recent work has identified NPHP as a "ciliopathy", caused by mutations in genes, whose proteins localize to the centrosome and/or primary cilium, and has generated a unifying pathogenic concept for NPHP-related ciliopathies (NPHP-RC). Despite the identification of mutations in more than 30 genes as causative of NPHP-RC, little is known about the molecular mechanisms underlying the disease. Recently, by whole exome resequencing I was involved in the identification of 3 novel genes - CEP164, FAN1 and SDCCAG8 as causing NPHP-RC with renal degeneration/fibrosis when mutated. Surprisingly, the centrosomal proteins CEP164 and SDCCAG8 were also localized at cell nuclei, and their inactivation led to impaired DNA damage response (DDR) signaling accompanied by cell cycle defects. Hence, together with FAN1, which is a known DNA damage repair protein, CEP164 and SDCCAG8 implicate defective DDR signaling as a novel pathomechanism of NPHP-RC. I hypothesize that renal degeneration/fibrosis in NPHP-RC is caused by defects in DNA damage response pathways. To test this hypothesis, I will (1) examine the role of "ciliopathy proteins" in regulating the DNA damage response pathway using the Cep164 and Sdccag8 mouse models of renal fibrosis; (2) perform a high-throughput screen for small molecules that influence and counteract the NPHP-RC pathogenesis; (3) characterize the functions and regulation of trafficking of CEP164 and SDCCAG8 between their dual localizations at centrosomes and in nuclei. Accomplishment of the proposed research will provide (1) new insights into the pathomechanisms of ciliopathies; (2) new chemical compounds that can lead to therapies for NPHP-RC and renal fibrosis; (3) new animal models for studying DDR-related diseases. The objective of this K99/R00 application is to utilize the newly generated animal models for the study of molecular mechanisms of NPHP-RC. This will facilitate the transition of my research career towards an independent investigator position. The training (K99) phase of this award will be mentored by Dr. Friedhelm Hildebrandt, who is an investigator of Howard Hughes Medical Institute and internationally recognized leader in the fields of human genetics and of pediatric kidney diseases. In March 2013 I will move to the Boston Children's Hospital (BCH)/Harvard Medical School (HMS) with Dr. Hildebrandt's laboratory. My long-term career goal is to establish myself as an independent investigator in the field of kidney research, focusing on animal models of kidney diseases. The BCH/HMS has several collaborative research groups working on kidney development and diseases providing an ideal environment for my training and career development.