Genetics of Autosomal Dominant Polycystic Liver Disease

描述(由申请者提供)：我们的研究计划集中于实现对人类多囊肝和肾脏疾病的全面分子理解。我们的目标是发现有效治疗患者的新范例。我们采取了一种方法，首先通过位置克隆发现疾病基因，以了解疾病的遗传基础，然后进行功能研究，以了解细胞发病机制。在目前的资助下，我们招募了孤立的常染色体显性遗传性多囊肝病(ADPLD；MIM 174050)患者，并完成了该疾病的全面临床特征。我们建立了一个座位PLD1的遗传连锁，并发现了致病基因PRKCSH。我们在6号染色体上确定了ADPLD的第二个基因座，并将人类SEC63鉴定为PLD2。这些基因的突变约占我们队列中ADPLD先证者的25%，这表明至少有一个额外的基因位点PLD3与ADPLD有关。PRKCSH编码葡萄糖苷酶II(GIIB)的B亚基，GIIB是一种葡萄糖修剪酶，参与内质网中蛋白质的成熟和质量控制。SEC63编码ER蛋白转位机制的一个组成部分，该机制与GII协同工作，实现完整的膜或分泌的糖蛋白的正确拓扑和折叠。这一建议试图通过发现更多与ADPLD有关的基因，通过确定ADPLD是否需要两次HIT才能形成囊肿，以及通过确定内质网中的蛋白质成熟与胆管上皮初级纤毛的正常功能之间的关系，来进一步确定包囊形成的细胞途径。我们建议使用“经典”位置克隆和候选基因相结合的方法来识别与ADPLD有关的其他基因(如PLD3)。我们将使用小鼠模型来检验这一假设，即ADPLD的囊性形成需要躯体二次打击，就像ADPKD的情况一样。我们将确定Prkcsh和Sec63突变是否导致PKD 1、PKD2和Pkhd 1基因产物的不成熟和纤毛传递。这些研究将通过利用我们发现的PRKCSH和SEC63作为疾病基因而可能的致病途径的新切入点，提高我们对多囊疾病的细胞和分子基础的理解。与此同时，我们将提高我们对ADPLD作为一种疾病状况的理解，并开发有助于受这种状况影响的患者的见解。

DESCRIPTION (provided by applicant): Our research program centers on achieving a comprehensive molecular understanding of human polycystic liver and kidney disease. Our goal is discovery novel paradigms for effective treatment of patients. We have taken an approach that begins with disease gene discovery through positional cloning to understand the genetic bases for the diseases, followed by functional studies to understand cellular pathogenesis. Under the current grant, we recruited patients with isolated autosomal dominant polycystic liver disease (ADPLD; MIM 174050) and completed a comprehensive clinical characterization of the disease. We established genetic linkage for one locus, PLD1, and discovered the disease gene, PRKCSH. We identified a second locus for ADPLD on chromosome 6 and identified human SEC63 as PLD2. Mutations in these genes account for ~ 25% of ADPLD probands in our cohort and suggest that there is at least one additional locus, PLD3, for ADPLD. PRKCSH encodes the B-subunit of glucosidase II (GIIB), a glucose trimming enzyme involved in protein maturation and quality control in the ER. SEC63 encodes a component of the ER protein translocation machinery that functions in concert with GII to achieve proper topology and folding of integral membrane or secreted glycoproteins. This proposal seeks to further define cellular pathways to cyst formation by discovery of additional genes involved in ADPLD, by determining whether two hits are required for cyst formation in ADPLD, and by defining the relationship between protein maturation in the ER and the normal function of primary cilia in bile duct epithelium. We propose to identify additional genes (e.g., PLD3) responsible for ADPLD by use of a combination of "classical" positional cloning and candidate gene approaches. We will use mouse models to test the hypothesis that cyst formation in ADPLD requires somatic second hits as is the case in ADPKD. We will determine whether Prkcsh and Sec63 mutations result in improper maturation and cilial delivery of the Pkd 1, Pkd2 and Pkhd 1 gene products. These studies will improve our understanding of the cellular and molecular bases of polycystic diseases by using the novel entry points into the pathogenic pathways made possible by our discovery of PRKCSH and SEC63 as disease genes. At the same time, we will improve our understanding of ADPLD as a disease condition and develop insights that will help patients affected by this condition.