| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
1. We previously reported an AQP2 gene mutation (763 -772de1) causing autosomal dominant nephrogenic diabetes insipidus (NDI). To determine the cellular pathogenesis of the NDI, MDCK cells were transfected with the wild-type AQP2, or the 763-772de1, or both. Immunofluorescence microscopy showed that the wild-type AQP2 and the 763-772de1 were expressed in the apical and basolateral region, respectively. When they were cotransfected, mixed oligomers of the wild-type AQP2 and the 763-772de1 were mistargeted to the basolateral membrane due to the dominant negative effect of the mutant. This defect is likely to explain the pathogenesis of autosomal dominant NDI.
2. To determine we the role of AQP2 C-terminus for apical trafficking, C-terminal mutants of AQP2 were transfected into MDCK cells to determine the part responsible for apical trafficking. Our Tresults suggest that the last 10 amino acids are the determinant for apical trafficking of AQP2.
3. We identified two novel AQP2 gene mutation (Q57P, GlOOV) causing autosomal recessive NDI. When these mutant AQP2s were expressed in Xenopus oocytes, they were retained in intracellular compartment, suggesting the NM is caused by the trafficking defect.
4. We examined the osmotic regulation of AQP1 expressed in cultured mesothelial cells in peritoneum. Exposure to hyperosmolality significantly increased the expression of AQP1 and cell water penneability after 24 hours, suggesting upregulation of AQP1 by hyperosmolality.
5. We cloned a novel water channel, AQP1-. AQP10 was specifically expressed in ileum. Xenopus oocyte expression study revealed that AQP1O permeates glycerol in addition to water.
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