Polycystin-1, ATP-induced Ca2+ entry & C1 - conductance

Polycystin-1，ATP 诱导 Ca2+ 进入

基本信息

批准号：
6894730
负责人：
MICHAEL SUTTERS
金额：
$ 13.39万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-09-01 至 2009-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common hereditary diseases, causing loss of renal function that leads to dialysis treatment in some 1800 new patients a year. The disease, arising from mutations in the PKD 1 gene encoding polycystin-1, is characterized by the presence of multiple renal cysts. Expansion of these cysts correlates closely with loss of renal function and is driven by transepithelial fluid secretion. The objective of this KO8 proposal is to understand why loss of polyeystin-1 results in fluid secretion and cyst expansion. ATP is a potent and universal stimulus for fluid secretion and might therefore play a role in ADPKD: All the components required for ATP-stimulated chloride secretion are resident in the cyst environment. ATP acts through heterotrimeric G proteins (Glphabetagamma) to cause an initial burst of calcium release from the endoplasmic reticulum (ER), which in turn triggers a prolonged phase of calcium entry from outside the cell (agonist induced calcium entry or ACE). ACE is also triggered by ER store-independent pathways linked to Galphabetagamma. Increased ATP-stimulated chloride secretion could arise from loss of polycystin-1 through disruption of its known effects upon ACE-type channels and Galphabetagamma. In preliminary experiments it was demonstrated that expression of the isolated C-terminal 193 amino acids of polycystin-1 (sIg-PKD193 fusion protein) augmented ATP-stimulated chloride secretion through up-regulation of store independent ACE in a cortical collecting duct cell line. Over-expressed polycystin-1 had the opposite effect, abbreviating the cell calcium response to ATP, suggesting that the slg-PKD193 fusion protein effect was the result of dominant negative inhibition of endogenous polycystin-1. It is hypothesized that: Polyeystin-1 down-regulates ATPstimulated chloride secretion through attenuation of store-independent agonist-induced calcium entry, and acts via modulation of heterotrimerie G protein coupled pathways. The experiments in Specific Aim #1 will define the effects of polycystin-1 upon the ER store dependent and independent components of ACE, and correlate these effects with the regulation of chloride channel activity. This will be done through over-expression and inhibition of polycystin-1. Specific aim #2 will identify the mechanism of the effect of polycystin-1 upon ACE, thereby providing a direct link between genetic lesion and fluid secretion. Dr. Michael Sutters has dedicated his career to becoming both a clinician and a scientist. He will be the principle investigator in this KO8 application. The long-term aim of his work is to facilitate the design of new therapeutic strategies to control disease progression through delineation of the mechanism of cyst expansion in ADPKD

描述（由申请人提供）：常染色体显性多囊性肾脏疾病（ADPKD）是最常见的遗传性疾病之一，导致肾功能丧失，每年约1800名新患者导致透析治疗。该疾病是由编码多囊蛋白1的PKD 1基因突变引起的，其特征是存在多个肾囊肿。这些囊肿的膨胀与肾功能的丧失密切相关，并由旋转液体分泌驱动。该KO8提案的目的是了解为什么Polyeystin-1的损失导致流体分泌和囊肿扩张。 ATP是液体分泌的有效刺激，因此可能在ADPKD中发挥作用：ATP刺激的氯化物分泌所需的所有成分均居住在囊肿环境中。 ATP通过异三聚体G蛋白（Glphabetagamma）起作用，从而导致钙从内质网（ER）引起初始的钙释放，从而导致钙从细胞外部触发钙的延长钙的延长（激动剂诱导的钙进入或ACE）。 ACE还由与Galphabetagamma相关的ER存储途径触发。通过破坏其对ACE型通道和Galphabetagamma的已知作用的损失，ATP刺激的氯化物分泌增加可能引起。在初步实验中，证明了多囊蛋白1（SIG-PKD193融合蛋白）分离的C末端193氨基酸的表达通过在皮质收集导管细胞系中的储存独立ACE上调，从而增强了ATP刺激的氯化物分泌。过表达的polycystin-1具有相反的作用，缩写对ATP的细胞钙反应，这表明SLG-PKD193融合蛋白效应是内源性多囊1的负面负抑制作用的结果。假设：Polyeystin-1通过衰减依赖储存的激动剂诱导的钙进入而下调的氯化物分泌，并通过调节异三聚体G蛋白偶联途径来起作用。特定目标＃1中的实验将定义polycystin-1对ACE依赖和独立成分的影响，并将这些影响与氯化物通道活性的调节相关联。这将通过过度表达和抑制多囊这1。特定的目标＃2将确定polycystin-1对ACE的作用的机制，从而在遗传病变和液体分泌之间提供直接联系。迈克尔·萨特斯（Michael Sutters）博士致力于成为临床医生和科学家。他将成为此KO8申请中的主要调查员。他的工作的长期目的是促进设计新的治疗策略，以通过划定ADPKD中囊肿扩张机制来控制疾病的发展