The Role of TGF-alpha in the Pathogenesis of ARPKD

说明(改编自应用程序) 常染色体隐性遗传性多囊肾病是一种遗传性肾脏 以大量肾肿大和肝纤维化为特征的疾病。 进展为终末期肾病通常是不可避免的，通常是在 生命的头几年。越来越多的文学作品确立了一个关键角色 针对表皮生长因子受体(EGFR)在发病机制中的异常 细胞增殖和囊性扩张。相比之下，表达，调节， 而EGFR配体的功能在这些方面还没有得到系统的研究 疾病。已公布的数据表明，EGFR配体，改变了生长 转化生长因子-α在囊性组织和细胞中高表达， 过度表达转化生长因子-α的转基因小鼠会患上肾囊肿。使用转化生长因子-α 作为一个范例，这项拟议的研究将检查 配体的上调及其与EGFR配体相关因素的确定 在ARPKD中过度表达。中心假设是异常的EGFR配体 表达是调节PKD细胞病理生理的共同特征。 该项目的具体目标是： 1.检测转化生长因子-α在囊内表达的生理学效应 转化生长因子-α的形成和扩增及其特异性因子的鉴定 上调。需要检验的具体假设包括：a)转化生长因子-α 上调导致自身产量增加(自动诱导)和 其他EGFR配体(交叉诱导)；b)分泌型，非膜结合型 转化生长因子-α，是ARPKD中更重要的生物活性部分；c) 转化生长因子-α通过直接作用于EGFR mRNA调节EGFR的表达 转录和稳定性；以及d)AP-2和VHL的异常表达， 已知的调节转化生长因子-α表达的因子，介导转化生长因子-α的增加 在ARPKD中表达。原代和永生化集合管细胞系 来源于囊性Bpk小鼠(ARPKD的小鼠模型)和非囊性Bpk小鼠 将使用小鼠来评估外源转化生长因子-α的体外效应。 给药、转化生长因子-α的过度表达和转化生长因子-α/表皮生长因子受体的相互作用。AP-2 VHL蛋白和mRNA在囊性和对照组织和细胞中的表达 以及每种蛋白在转化生长因子-α调节中的作用 评估过了。 2.检测阻断转化生长因子-α产生对疾病的体内影响 ARPKD的进展。需要检验的假设是，转化生长因子-α有一个关键 在ARPKD发病机制中的作用。这将通过培育Bpk来进行测试。 转化生长因子-α基因敲除小鼠及其对疾病的影响 EGFR及其他EGFR配体的进展和表达。 这些研究将为EGFR配体的生物学提供新的见解 ARPKD.虽然拟议的研究重点是ARPKD，但由 这些研究可能有助于更广泛地理解常染色体显性 还有多囊肾病(ADPKD)。

DESCRIPTION (adapted from the application) Autosomal recessive polycystic kidney disease (ARPKD) is an inherited kidney disorder characterized by massive kidney enlargement and hepatic fibrosis. Progression to end-stage renal disease is usually inevitable, often in the first years of life. A growing body of literature has established a key role for the epidermal growth factor receptor (EGFR) in the pathogenesis of abnormal cell proliferation and cyst expansion. In contrast, the expression, regulation, and function of the EGFR ligands have not been studied systematically in these diseases. Published data demonstrate that the EGFR ligand, transforming growth factor-alpha (TGF-alpha), is overexpressed in cystic tissues and cells and transgenic mice that overexpress TGF-alpha develop renal cysts. Using TGF-alpha as a paradigm, the proposed research will examine the physiologic effects of ligand upregulation and identify factors that contribute to EGFR ligand overexpression in ARPKD. The central hypothesis is that aberrant EGFR ligand expression is a common feature modulating the cellular pathophysiology of PKD. The specific aims of the project are: 1. To examine the physiologic effects of TGF-alpha upregulation in cyst formation and enlargement and to identify specific factors mediating TGF-alpha upregulation. Specific hypothesis to be tested include: a) TGF-alpha upregulation results in increased production of itself (auto-induction) and other EGFR ligands (cross-induction); b) secreted, not membrane-bound TGF-alpha, is the more important biologically-active moiety in ARPKD; c) TGF-alpha regulates EGFR expression by direct effects on EGFR mRNA transcription and stability; and d) abnormal expression of AP-2 and VHL, factors known to regulate TGF-alpha expression, mediate increased TGF-alpha expression in ARPKD. Primary and immortalized collecting tubule (CT) cell lines derived from cystic bpk mice (a murine model of ARPKD) and noncystic littermates will be used to assess the in vitro effects of exogenous TGF-alpha administration, TGF-alpha overexpression, and TGF-alpha/EGFR interactions. AP-2 and VHL protein and mRNA expression in cystic and control tissues and cells will be determined, and the role of each protein in TGF-alpha regulation assessed. 2. To determine the in vivo effects of blocking TGF-alpha production on disease progression in ARPKD. The hypothesis to be tested is that TGF-alpha has a key role in the pathogenesis of ARPKD. This will be tested by breeding the bpk mouse with a TGF-alpha knockout mouse and assessing the impact on disease progression and expression of EGFR and other EGFR ligands. These studies will provide new insights into the biology of EGFR ligands in ARPKD. Although the proposed research focuses on ARPKD, insights provided by these studies may contribute to a broader understanding of autosomal dominant polycystic kidney disease (ADPKD) as well.