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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(AQPs)的克隆我们从大鼠睾丸克隆了AQP7，从大鼠睾丸克隆了对甘油和尿素除水有通透性的AQP7，从大鼠睾丸克隆了对水有选择性的AQP8，从人白细胞克隆了除水外对尿素有通透性的AQP9，从大鼠肝脏克隆了AQP9L，它是AQP9的同源物。2)AQP结构的测定。我们在人类AQP3中发现了汞敏感的半胱氨酸，并有证据表明水、甘油和尿素共享一个共同的孔。AQP家族分为两组：对水有选择性的MIP组和对小分子具有通透性的glpF组。只有后者有两个部分，由大约15个氨基酸组成。我们检查了这些部分的重要性，发现这些部分与频道选择性无关。AQP2与MIP有很高的同源性(氨基酸同源性为58%)，而AQP2的透水性远远高于MIP。我们构建了AQP2和MIP的嵌合体蛋白，并确定了跨膜Helix5中的几个氨基酸与AQP2的高透水性有关。与尿液浓度相关的细胞内机制和信号转导。短时间或长时间暴露于高渗透压可降低大鼠内髓集合管细胞Na-K-ATPase活性。我们发现短时间和长时间暴露对Na-K-ATPase的抑制机制不同。我们研究了LLC-PK1和系膜细胞中的信号转导途径，并获得了几个新的发现。肾源性尿崩症(NDI)a的发病机制。我们对常染色体隐性遗传NDI中发现的AOP2突变体T125M和G175R进行了鉴定，发现这些突变体的水通道功能降低。我们对常染色体显性遗传NDI中发现的809del 7和AQP2突变进行了鉴定，发现该突变导致转录抑制或蛋白质转运缺陷。