title: Identification of a novel aquaporin, AQP12, expressed in pancreatic acinar cells.
abstract: Members of the aquaporin (AQP) water channel family are widely distributed in various tissues and contribute to the water permeability of epithelial and endothelial cells. Currently 11 members of the AQP family (AQP0-10) have been reported in mammals. Here we report the identification of AQP12, which we found by performing a BLAST program search. Northern blot analysis revealed that AQP12 was specifically expressed in the pancreas. Further analysis by in situ hybridization and RT-PCR studies showed that AQP12 was selectively localized in the acinar cells of the pancreas. To analyze the cellular localization and function of AQP12, we expressed AQP12 in Xenopus oocytes and cultured mammalian cells. Immunocytochemistry revealed that AQP12 was not targeted to the plasma membrane. The selective localization of AQP12 in pancreatic acinar cells and possibly in the intracellular organelles suggests a role of AQP12 in digestive enzyme secretion such as maturation and exocytosis of secretory granules.
authors.affiliation: Department of Nephrology, Graduate School of Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo, Tokyo 113-8519, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Itoh
authors.forename: Tatemitsu
authors.initials: T
authors.lastname: Rai
authors.forename: Michio
authors.initials: M
authors.lastname: Kuwahara
authors.forename: Shigeru B H
authors.initials: SB
authors.lastname: Ko
authors.forename: Shinichi
authors.initials: S
authors.lastname: Uchida
authors.forename: Sei
authors.initials: S
authors.lastname: Sasaki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishibashi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020346:Aquaporins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D009928:Organ Specificity; D010179:Pancreas / Q000166:cytology* / Q000378:metabolism*; D010802:Phylogeny; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014982:Xenopus laevis
chemical_list: C501068:AQP12 protein, mouse; C501067:AQP12A protein, human; D020346:Aquaporins; D018076:DNA, Complementary; D012333:RNA, Messenger