1998 Fiscal Year Final Research Report Summary
STRUCTURE AND FUNCTION OF PEPTIDE SIGNALS FOR INTRACELLULAR LOGALIZATION OF AQP2 VASOPRESSIN WATER CHANNEL
| Project/Area Number |
09671154
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Kidney internal medicine
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| Research Institution | Tokyo Medical and Dental University School of Medicine |
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Principal Investigator |
TOUJOU Naoko TOKYO MEDICAL AND DENTAL UNIVERSITY SCHOOL OF MEDICINE,DEPARTMENT OF LABORATORY MEDICINE,ASSISTANT PROFESSOR, 医学部, 助手 (90227554)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Sei TOKYO MEDICAL AND DENTAL UNIVERSITY SCHOOL OF MEDICINE,SECOND DEPARTMENT OF INTE, 医学部, 助教授 (60170677)
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| Project Period (FY) |
1997 – 1998
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| Keywords | WATER CHANNEL / CELL POLARITY / VASOPRESSIN / KIDNEY COLLECTING DUCT / AQUAPORIN |
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| Research Abstract |
The purposes of this research were to identify molecular structure and regulatory mechanisms of vasopressin water charnel AQP2 In kidney collecting duct, and to detennine peptide signals for intracellular localization of NQP2.
First, we examined mo1ecular structure of AQP2, which was first cloned by the head investigator, using molecular techniques of site-directed mutagenes is and gene expression. We were able to localize the aqueous pore in the AQP2 molecule and proposed a three-dimensional structure model of AOP2. In our model aqueous pore of AQP2 is composed of two of five hydrophilic loops of AQP2, which is a membrane protein with six transmenbrane segments connected by five hydrophilic loops.
Second. we found that intracellular trafficking of AQP2 is involved in the vasopressin regulation of osmotic water permeability of kidney collecting duct apical membrane. It was observed that, after vasopressin stimulation, AQP2 stored on endosomal membrane was transferred to the surface mentrane with exocytosis of vesicles from cytoplasm to the apical membrane, resulting in the increase of osmotic water permeability of the apical mentrane. In these regulatory steps, we proved that phosphorylation of serine 256 by protein kinase A is required for cAMP-dependent regulatory exocytosis of AQP2.
Third, we examined function and intracellular localization of four AQP2 mutants. T125M, A147T, R187C.S216P, that cause nephrogenic diabetes insipidus. It was found that A147T mutation alters water permeability but dose not alter intracellular channel localization but other mutants alter channel localization. We speculate that molecular structure near A147T is critical for channel function but not significant for intracellular trafficking.
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[Publications] Yamauchi, K,Fushimi, K,Yamashita, Y,Shinbo, I,Sasaki, S,Marumo F.: "Effects of missense mutations on the function and intracellular localization of rat aquaporin-2 in LLC-PK1 porcine kidney cells." Kidney International. (IN PRINT). (1999)
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