2000 Fiscal Year Final Research Report Summary
Expression of Aquaporins in Ileal W-type reservoir
| Project/Area Number |
11671214
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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 |
Digestive surgery
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| Research Institution | NIIGATA UNIVERSITY |
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Principal Investigator |
SUDA Takeyasu School of Medicine, NIIGATA UNIVERSITY, Lecturer, 医学部, 講師 (50251806)
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| Co-Investigator(Kenkyū-buntansha) |
IIAI Tsuneo University Medical Hospital, NIIGATA UNIVERSITY, Assistant, 医学部・附属病院, 助手 (10323982)
SATOH Nobuaki University Medical Hospital, NIIGATA UNIVERSITY, Associate Professor, 医学部・附属病院, 助教授 (90215822)
OKAMOTO Haruhiko University Medical Hospital, NIIGATA UNIVERSITY, Assistant, 医学部・附属病院, 助手 (90301184)
YAMAMOTO Tadashi School of Medicine, NIIGATA UNIVERSITY, Professor, 医学部, 教授 (30092737)
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| Project Period (FY) |
1999 – 2000
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| Keywords | water channel / AQP8 / AQP9 / colon / subtotal colectomy / ulcerative colitis / ileal W-pouch / colonization |
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| Research Abstract |
<STUDY 1>
Human aquaporin 8 (AQP8) cDNA was isolated from a human large intestine cDNA library by homology cloning. The open reading frame encoded 261 amino acid protein and the amino acid sequence was 75% identical to rat AQP8 and 76% identical to mouse AQP8. Expression of human AQP8 cRNA in Xenopus oocytes increased osmotic water permeability in a mercury-sensitive manner, indicating a water channel function of this molecule. Northern blot analysis and ribonuclease protection assay showed intense expression of 〜1.35-kilobase human AQP8 transcript in pancreas and colon, and weak expression in appendix and rectum. By in situ hybridization, AQP8 mRNA expression was localized in absorptive colonic epithelial cells, suggesting a role of AQP8 in the water absorption in the colon. The human AQP8 gene was mapped to 16p11.2-p12 by radiation hybrid mapping.
<STUDY 2>
[Background] Water has been presumed to move between epithelial cells (paracellular route) by interpretation of electrophysiological studies. But recently, water channel (AQP) mRNA espression was demonstrated in the gastrointestinal tract, and transcellular route of water for absorption and secretion was suggested.
[Purpose] Using a rat subtotal colectomy model, we investigated the role of AQP in the intestinal tract.
[Method] The effects of surgical resection on the expression of AQP mRNA were assesed by a RNase Protection Assay.
[Results] After subtotal colectomy, expression of rat AQP8 mRNA was markedly increased in the remnant colon.
[Discussion] Induction of AQP mRNA in remnant colon may contribute to the recovery from the increased water loss after subtotal colectomy.
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[Publications] Yu Koyama, Tadashi Yamamoto, Tatsuo Tani, Kouei Nihei, Daisuke Kondo, Haruko Funaki, Eishin Yaoita, Katsutoshi Kawasaki, Nobuaki Sato, Katsuyoshi Hatakeyama, Itaru Kihara.: "Expression and Localization of Aquaporin in rat gastrointestinal tract."Am.J.Physiol.. 276. C621-627 (1999)
Description
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