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Mechanisms and regulation of renal urinary concentration

肾尿浓度的机制和调节

基本信息

批准号：
09307022
负责人：
TERADA Yoshio
金额：
$ 25.28万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

1) Cloning of water channels (AQPs)We cloned the following AQPs ; AQP7 from rat testis that has permeability to glycerol and urea in addition to water, AQP8 from rat testis that is water-selective, AQP9 from human leukocyte that has permeability to urea in addition to water, and AQP9L, a homologue of AQP9, from rat liver.2) Determination of AQP structurea. We identified mercury-sensitive cystein in human AQP3 and showed evidence suggesting that water, glycerol, and urea share a common pore.b. AQP family is divided into two groups ; MIP group that is water-selective and glpF group that is permeable to small molecules. Only the latter group possesses two portions which are composed of about 15 amino acid. We examined the significance of these portions and found the portions are not associated with channel selectivity.c. AQP2 and MIP are highly homologous (58% amino acid homology), whereas the water permeability of AQP2 is much higher than that of MIP. We constructed chimera proteins of AQP2 and MIP and determined several amino acids in transmembrane helix5 is responsible for the high water permeability of AQP.3. Intracellular mechanisms and signal transduction related to urinary concentrationa. A short or a long time exposure to high osmolality decreased the activity of Na-K-ATPase in rat inner medullary collecting duct cells. We found that the mechanism of Na-K-ATPase inhibition was different in the short and long time exposure.b. We investigated signal transduction pathways in LLC-PK1 and mesangial cells and obtained several new findings.4. Pathogenesis of nephrogenic diabetes insipidus (NDI)a. We characterized T125M and G175R, AOP2 mutants found in autosomal recessive NDI, and found the decrease of the water channel function of these mutants.b. We characterized 809del 7, and AQP2 mutant found in autosomal dominant NDI, and found that this mutation causes the inhibition of transcription or the defect of protein trafficking.

1）水通道（AQP）的克隆我们克隆了以下AQP；来自大鼠睾丸的AQP7，对甘油和尿素以及水具有通透性；AQP8来自大鼠睾丸，具有水选择性；AQP9来自人白细胞，对尿素和水都具有通透性；AQP9L（AQP9的同源物）来自大鼠肝脏。2）AQP结构的测定a。我们在人 AQP3 中鉴定出了对汞敏感的半胱氨酸，并提供了证据表明水、甘油和尿素共享一个共同的孔。 AQP家族分为两组； MIP 基团具有水选择性，glpF 基团可渗透小分子。只有后者拥有两个由大约15个氨基酸组成的部分。我们检查了这些部分的重要性，发现这些部分与通道选择性无关。c． AQP2和MIP高度同源（58%氨基酸同源性），而AQP2的透水性远高于MIP。我们构建了AQP2和MIP的嵌合蛋白，并确定了跨膜螺旋5中的几个氨基酸负责AQP.3的高透水性。与尿浓度相关的细胞内机制和信号转导。短期或长期暴露于高渗透压会降低大鼠内髓集合管细胞中Na-K-ATP酶的活性。我们发现Na-K-ATP酶抑制机制在短时间和长时间暴露下是不同的。我们研究了LLC-PK1和系膜细胞的信号转导通路，并获得了一些新的发现。 4．肾性尿崩症（NDI）的发病机制a。我们对常染色体隐性NDI中发现的T125M和G175R、AOP2突变体进行了表征，发现这些突变体的水通道功能下降。我们对常染色体显性 NDI 中发现的 809del 7 和 AQP2 突变体进行了表征，发现该突变导致转录抑制或蛋白质运输缺陷。