RENAL TUBULOGENESIS AND THE ROLE OF HGF/SF AND SYNTAXINS

许多重要器官，包括肾脏，都是由于 间质-上皮相互作用。这些相互作用的中介是 肝细胞生长因子，a. K. a.散射因子（HGF\SF）。HGFISF是 间充质源性生长因子和上皮c- rnet受体虽然HGFISF不是肾毒性的唯一诱导剂， 发育和小管形成，它诱导小管形成， 和体外ii Madin-Darby犬肾（MDCK）细胞，其是 来源于犬肾小管上皮细胞。 生成和 维持细胞极性对上皮细胞功能是必不可少的。到 建立并维持其极性，上皮细胞，包括MDCK，细胞 必须将质膜（PM）蛋白质发送到（正确的顶端或 基底外侧PM。初步结果表明，当HGF/SF诱导 当MDCK细胞分支出来时，它们失去极性 然后在新的小管形成时重新获得极性。 近年来的一个重大发现是，几乎所有的细胞内 膜运输使用膜融合的普通机制。 突触融合蛋白是一个基因家族，是膜融合的组成部分 机器，似乎指定正确交付给不同的PM 表面。突触融合蛋白2、3和4在上皮器官中丰富，例如， 肾发现突触融合蛋白2、3和4的表达差异 在MDCK细胞中，突触融合蛋白3和4具有完全非- 重叠分布突触融合蛋白是第一个分子， 膜融合机制，其亚型是不同的 局部的，其过度表达对极化的 膜交通因此，他们是领先的候选人， 至少包含维护所需的部分信息 细胞极性 假设细胞极性的短暂丧失是 对肾小管形成至关重要：而突触融合蛋白参与控制 细胞极化并因此形成小管。 的表达和 将在HUF/SF诱导期间检查突触融合蛋白的定位。 MDCK细胞中的小管形成，啮齿动物肾脏的正常发育， 以及疾病的异常发展，比如多囊肾， 疾病和肾细胞癌。为了直接检验假设， 表达不同的语法融合蛋白的功能将受到干扰， 过表达、表达抑制和显性负性 变种人如果突触融合蛋白的表达对小管形成很重要， 可以考虑寻找改变语法表达的方法 在疾病状态下，也许通过使用病毒载体的基因治疗。

Many vital organs, including the kidney, form as a result of a mesenchymal-epithelial interaction. A mediator of these interactions is hepatocyte growth factor, a. k. a. scatter factor, (HGF\SF). HGFISF is mesenchymally-derived growth factor and ligand for the epithelial c- rnet receptor. Though HGFISF is not the only inducer of renal development and tubulogenesis, it induces tubulogenesis both in vivo and in vitro ii Madin-Darby canine kidney (MDCK) cells, which are derived from canine renal tubular epithelium. Generation and maintenance of cell polarity is essential to epithelial cell function. To establish and maintain their polarity, epithelial, including MDCK, cells must send plasma membrane (PM) proteins to th( correct apical or basolateral PM. Preliminary results show that when HGF/SF induced tubulogenesis occurs MDCK cells lose their polarity as they branch out and then regain their polarity as the new tubules form. A major discovery in recent years is that almost all intracellular membrane traffic uses a common machinery for membrane fusion. Syntaxins are a gene family and component of the membrane fusion machinery that appear to specify correct delivery to the different PM surfaces. Syntaxins 2, 3, and 4 are abundant in epithelial organs, e.g. kidney. Syntaxins 2, 3, and 4 were found to be differentially expressed in MDCK cells, with syntaxins 3 and 4 having a completely non- overlapping distribution. Syntaxins are the first molecules that are part of the membrane fusion machinery, whose isoforms are differentially localized and whose overexpression has differential effects on polarized membrane traffic. Hence, they are the leading candidates for containing at least part of the information needed for the maintenance of cell polarity. The hypothesis is that transient loss of cell polarity i crucial for renal tubulogenesi: and syntaxins are involved in controlling cell poladty and therefore tubulogenesis. The expression and localization of syntaxins will be examined during HUF/SF induced tubulogenesis in MDCK cells, normal development of rodent kidneys, and abnormal development in disease states such a polycystic kidney disease and renal cell carcinoma. To directly test the hypothesis, the expression an function of different syntaxins will be perturbed by overexpression, inhibition of expression, and dominar negative mutants. If the expression of syntaxins is important for tubulogenesis, consideration can be given t finding ways to alter syntaxin expression in disease states, perhaps by gene therapy using viral vectors.