title: Expression of aquaporin-1 in human peritoneal mesothelial cells and its upregulation by glucose in vitro.
abstract: Aquaporin (AQP) is a family of water channels that are highly selective for the passage of water and occasionally glycerol. In previous studies, only AQP1 was found in human peritoneal endothelial cells in both control subjects and patients on peritoneal dialysis. As human peritoneal mesothelial cells (HPMC) play an important role in dialysis adequacy and fluid balance in continuous ambulatory peritoneal dialysis patients, this study examined whether AQP1 is present in HPMC. It was found that AQP1 mRNA and protein are present in HPMC constitutively. The localization of AQP1 protein in peritoneal mesothelial cells was confirmed by double immunohistochemical staining of the mesothelial lining of human peritoneal membrane. More important, the expression of AQP1 in HPMC is not constitutive and the transcription and biosynthesis of AQP1 in HPMC is inducible by osmotic agents such as glucose and mannitol. There was significant enhancement of AQP1 biosynthesis upon exposure to glucose in a time- and dose-dependent manner (P < 0.0001). Similar findings were observed in the AQP1 biosynthesis by an endothelial cell line, EA.hy 926. Of particular interest, the upregulation in AQP1 mRNA or biosynthesis in mesothelial cells was always significantly higher than that of endothelial cells when the experiments were conducted under identical settings (P < 0.001). AQP1 expression in HPMC was demonstrated for the first time. Osmotic agents upregulate both mRNA and protein expression of this aquaporin. The role of AQP1 in HPMC in maintaining the ultrafiltration of the peritoneal membrane is potentially of clinical interest.
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Kar Neng
authors.initials: KN
authors.lastname: Lai
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Fu Keung
authors.initials: FK
authors.lastname: Li
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Hao
authors.initials: H
authors.lastname: Yui Lan
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Sydney
authors.initials: S
authors.lastname: Tang
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Anita W L
authors.initials: AWL
authors.lastname: Tsang
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Daniel T M
authors.initials: DTM
authors.lastname: Chan
authors.affiliation: Division of Nephrology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Leung
mesh_terms: D051398:Aquaporin 1; D020346:Aquaporins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001789:Blood Group Antigens; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D010529:Peritoneal Cavity / Q000166:cytology*; D010537:Peritoneum / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C496020:AQP1 protein, human; D020346:Aquaporins; D001789:Blood Group Antigens; D017931:DNA Primers; D012333:RNA, Messenger; D051398:Aquaporin 1; D005947:Glucose