The Role of TGF-alpha in the Pathogenesis of ARPKD

描述（改编自应用程序） 常染色体隐性遗传性多囊肾病（ARPKD）是一种遗传性肾病， 一种以肾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，通常在 生命的最初几年。越来越多的文学作品已经确立了 表皮生长因子受体（EGFR）异常的发病机制 细胞增殖和包囊扩张。相反，表达，调节， EGFR配体的功能尚未在这些研究中系统地研究。 疾病已发表的数据表明，EGFR配体，转化生长， 因子-α（TGF-α）在囊性组织和细胞中过表达， 过度表达TGF-α的转基因小鼠会发生肾囊肿。使用TGF-α 作为一个范例，拟议的研究将检查的生理影响， 配体上调并鉴定促进EGFR配体的因子 在ARPKD中过度表达。中心假设是异常的EGFR配体 表达是调节PKD的细胞病理生理学的共同特征。 该项目的具体目标是： 1.检测囊肿中TGF-α上调的生理效应， 形成和扩大，并确定介导TGF-α的特异性因子 上调。待检验的具体假设包括： 上调导致自身产生增加（自诱导）， 其他EGFR配体（交叉诱导）; B）分泌的，非膜结合的 TGF-α是ARPKD中更重要的生物活性部分; c） TGF-α通过直接作用EGFR mRNA调节EGFR表达 转录和稳定性;和d）AP-2和VHL的异常表达， 已知调节TGF-α表达的因子，介导TGF-α增加 在ARPKD中的表达。原代和永生化集合管（CT）细胞系 来源于囊性bpk小鼠（ARPKD的鼠模型）和非囊性bpk小鼠（ARPKD的鼠模型）。 将使用同窝仔来评估外源性TGF-α的体外作用 在一些实施方案中，本发明涉及施用、TGF-α过表达和TGF-α/EGFR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 将被确定，每种蛋白质在TGF-α调节中的作用 评估。 2.为了确定阻断TGF-α产生对疾病的体内影响， ARPKD的进展。有待验证的假设是，TGF-α具有关键的 在ARPKD发病机制中的作用。这将通过繁殖bpk进行测试 小鼠与TGF-α敲除小鼠的比较，并评估对疾病的影响 EGFR和其他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 这些研究可能有助于更广泛地了解常染色体显性遗传 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.