The Proteolytic Cleavage of Polycystin-1: How and Why

描述（由申请人提供）：常染色体显性遗传性多囊肾病（ADPKD）是人类最常见的遗传性疾病之一，在美国每千人中就有一人患病。患者双肾出现多个囊肿。囊肿逐渐导致正常肾脏结构的破坏，并最终导致约50%的患者在60岁时发生终末期肾衰竭。目前还没有治愈这种疾病的方法。ADPKD主要由PKD 1基因突变引起，该基因编码多囊蛋白-1（PC 1）蛋白。因此，了解PC 1的正常结构和功能对于开发有效的治疗方法至关重要。我们以前已经发现，PC 1是蛋白水解切割的G-蛋白偶联受体蛋白水解位点（GPS）在几乎所有的细胞类型和组织在体内。这种反应，GPS裂解，产生了许多以前未识别的PC 1产物。在ADPKD患者的一个亚组中发现了PC 1的GPS切割缺陷。我们假设GPS裂解对于PC 1在肾脏中的完整功能是必不可少的。我们最近已经证明，使用一种新的小鼠模型，GPS裂解的PC 1是必不可少的适当的结构和功能的远端肾段在肾脏中，但显然是不需要的近端段和胚胎发育。我们现在提出，PC 1的裂解产物是肾脏中肾单位远段结构完整性的关键。该基金旨在了解GPS裂解调节PC 1在肾脏中的重要功能的机制。我们提出了三个互补的具体目标的研究，使用生物化学，生物物理，细胞生物学方法和动物模型的组合。具体目标1将在体外MDCK模型系统中分析GPS裂解产生的PC 1产物的结构和功能。这项研究可能会确立全球定位系统运作的基本原则。特异性目标2然后着眼于PC 1裂解产物在原代细胞中的作用，最后在小鼠中。特定目标3检查了近端节段不需要GPS切割的原因。拟议的研究可能会对PC 1在肾脏正常和疾病状态下的功能产生重要的见解。 公共卫生相关性 多囊蛋白-1是一种蛋白质，当有缺陷时会导致一种复杂的肾脏疾病，称为常染色体显性多囊肾病，目前还没有治愈方法。本研究旨在了解多囊蛋白-1，它成为缺陷的原因，以及预防它的方法。

DESCRIPTION (provided by applicant): Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common inherited disorders in humans, affecting one in a thousand people in the United States. Patients develop multiple cysts in both kidneys. The cysts progressively result in the destruction of the normal kidney structure and eventually lead to end-stage renal failure in approximately 50% of the patients by the age of 60. There are currently no cures for the disease. ADPKD is caused primarily by mutations of the PKD1 gene, which encodes polycystin-1 (PC1) protein. Therefore understanding of the normal structure and function of PC1 will be critical for the development of effective therapies. We have previously discovered that PC1 is proteolytically cleaved at the G-protein coupled receptor proteolytic site (GPS) in virtually all cell types and tissues in vivo. This reaction, the GPS cleavage, generates a number of previously unrecognized PC1 products. Defective GPS cleavage of PC1 has been found in a subset of ADPKD patients. We hypothesized that GPS cleavage is essential for the complete function of PC1 in the kidney. We have recently demonstrated using a novel mouse model that GPS cleavage of PC1 is essential for proper structure and function of the distal nephron segments in the kidney, but is apparently not required for that of the proximal segments and for embryonic development. We now propose that the cleavage products of PC1 are critically required for the structural integrity of distal segments of the nephron in the kidney. This grant aims at understanding the mechanism by which GPS cleavage regulates the important function of PC1 in the kidney. We propose the studies in three complementary Specific Aims using a combination of biochemical, biophysical, cell-biological methods and animal models. Specific Aim 1 will analyze structure and function of PC1 products generated by GPS cleavage in an in vitro MDCK model system. This study will likely establish basic principles of GPS functioning. Specific Aim 2 then looks at the role of the PC1 cleavage products in primary cells and finally in mice. Specific Aim 3 examines the reason why the proximal segments do not require GPS cleavage. The proposed studies will likely yield important insights into the function of PC1 in normal and disease states of the kidney. PUBLIC HEALTH RELEVANCE Polycystin-1 is the protein that when defective causes a complicated kidney disease known as autosomal dominant polycystic kidney disease, which at this point has no cure. This study aims to understand Polycystin-1, the reasons it becomes defective, and the ways to prevent it.