REGULATION OF NORMAL AND CYSTIC RENAL TUBULOGENESIS

肾小管形态发生和功能的发育异常 多囊肾病的特点，是一种主要的遗传性疾病 影响到美国50多万人的人类。的起因 这种疾病尚不清楚，但据推测，细胞数量增加 增殖和改变的经口液体运输是很重要的。我们的 长期目标是了解形态调节机制。 参与正常肾小管上皮组织的发育， 并确定这些机制在开发过程中是否发生改变 多囊肾病。我们已经建立了体外分析方法 肾上皮细胞发育(转滤器培养)及其作用 肾小管发生中的候选形态发生因子，将扩展到 对CPK小鼠囊性小管上皮细胞进行分析 多囊肾病。我们的初步研究表明，在早期 发育中的Na/K-ATPase暂时定位于顶膜 正常细胞的结构域，但在顶端持续表达 囊性上皮细胞的细胞膜。我们之前的结果表明， Na/K-ATPase在基底膜的正态分布为 通过细胞-细胞接触和与膜的相互作用而产生- 细胞骨架和膜脂。我们将检验这一假设 诱导肾小管生成的可溶性因子的异常调节 发育可导致肾小管上皮细胞增殖增加 结合Na/K-ATPase活性在根尖上的保留 囊性小管的形成： 1.明确Na/K-ATPase分布的时空规律 间充质诱导和向上皮细胞转化后 正常发育。Na/K-的表达和分布模式 将测定ATPase、膜细胞骨架和膜脂。 2.调控E-钙粘附素诱导的细胞间相互作用的时间 间充质转化与上皮细胞分化。的效果 抑制细胞间的接触对细胞分化和小管形成的影响 在后肾间质诱导和转化过程中，培养将 被分析。 3.间充质细胞诱导和上皮细胞分化的研究 从CPK小鼠的后肾组织中分离培养物。表达方式 以及Na/K-ATPase、膜细胞骨架和膜脂的分布 将被确定并在时间和空间上与正常的 发展。 4.分析调节可溶性因子的表达和功能。 正常和囊性上皮细胞的体外小管生成 分化和小管发生。散布的表现形式和功能 因子/肝细胞生长因子(SC/HGF)--一种有效的肾小管生成诱导剂 在体外培养的肾上皮细胞中，将在 从正常和囊性后肾发育的肾小管，以及 正常和囊性上皮细胞的纯化群体诱导形成 体外分枝的管状网。

Developmental abnormalities in renal tubule morphogenesis and function are characteristic of polycystic kidney disease, a major genetic disorder in humans that affects over 500,000 people in the United Stats. The cause of the disease is unknown, but it has been postulated that increased cell proliferation and altered transtubular fluid transport are important. Our long term objectives are to understand the morphoregulatory mechanisms involved in the development of normal renal tubule epithelia organization, and to determine whether these mechanisms are altered during development of polycystic kidney disease. We have established in vitro methods to analyze renal epithelial cell development (Transfilter Cultures), and the role of candidate morphogenetic factors in tubulogenesis that will be extended to analyze cells from cystic tubule epithelia of cpk mice, a murine model of polycystic kidney disease. Our preliminary studies show that in early development Na/K-ATPase is transiently localized to the apical membrane domain of normal cells, but is continuously expressed on the apical membrane in cystic epithelial cells. Our previous results indicate that the normal distribution of Na/K-ATPase at the basal-lateral membrane is generated by cell-cell contact and interactions with the membrane- cytoskeleton and membrane lipids. We will test the hypothesize that abnormal regulation of soluble factors that induce tubulogenesis in development could lead to increased cell proliferation of tubular epithelia and, combined with the retention of active Na/K-ATPase on the apical membrane, the formation of cystic tubules: 1. Define the temporal and spatial regulation of Na/K-ATPase distribution following mesenchyme induction and conversion to epithelial cells during normal development. Patterns of expression and distribution of Na/K- ATPase, membrane-cytoskeleton, and membrane lipids will be determined. 2. Modulate the timing of E-cadherin-induced cell-cell interactions during mesenchyme conversion and epithelial cell differentiation. Effects of inhibiting cell-cell contacts on cell differentiation and tubulogenesis during metanephrogenic mesenchyme induction and conversion in culture will be analyzed. 3. Investigate mesenchyme induction and epithelial cell differentiation in transfilter cultures from metanephroi of CPK mice. Patterns of expression and distribution of Na/K-ATPase, membrane-cytoskeleton, and membrane lipids will be determined and compared temporally and spatially to those in normal development. 4. Analyze the expression and function of soluble factors, that regulate tubulogenesis in vitro, on normal and cystic epithelial cell differentiation and tubulogenesis. Expression and function of Scatter Factor/Hepatocyte Growth Factor (SC/HGF), a potent inducer of tubulogenesis in renal epithelial cells in vitro, will be examined in cultures of developing renal tubules from normal and cystic metanephroi, and in purified populations of normal and cystic epithelial cells induced to form branching tubular networks in vitro.