title: Stress alters the expression of aquaporins in cultured rat intestinal epithelial cells.
abstract: Aquaporins (AQPs) are widely-expressed small water channel proteins that provide the major route for water transport across plasma membranes in various cell types. Although the quantity of water transported in the intestinal tract is second only to that in the kidney, the precise role of AQPs in this organ remains largely uncertain. The present study reports the effects of hypertonic stress and ischemia/reperfusion injury on the expression of AQPs in intestinal epithelial cells. Cultured rat intestinal epithelial cells were incubated in 300 mM mannitol-containing, hypertonic culture medium or subjected to simulated ischemia/reperfusion treatment. The cell viability was evaluated by MTT assay, and the expression of AQPs was determined by semi-quantitative reverse transcription polymerase chain reaction and western blotting. Despite reduced viability, the cells exposed to hypertonic stress for 16 h demonstrated enhanced expression of AQP1 mRNA and protein. AQP9 and glycosylated AQP11 proteins were also markedly upregulated. Ischemia alone did not affect the cell viability, but subsequent reperfusion significantly reduced viability. The mRNA expression levels of all the tested AQPs were not altered by ischemia alone or by ischemia/reperfusion; however, AQP8 protein was markedly reduced by ischemic injury. In addition, treatment with ischemia alone eradicated the normally-expressed, non-glycosylated AQP11 protein whilst inducing pronounced expression of the glycosylated form. These observations may indicate that AQPs function in the intestinal epithelia in response to stress.
authors.affiliation: Division of Plastic Surgery, Kaohsiung Armed Forces General Hospital, Kaohsiung 802, Taiwan, R.O.C. ; Department of Plastic Surgery, E-DA Hospital, Kaohsiung 824, Taiwan, R.O.C.
authors.forename: Jian-An
authors.initials: JA
authors.lastname: Chen
authors.affiliation: Department of Plastic Surgery, E-DA Hospital, Kaohsiung 824, Taiwan, R.O.C.
authors.forename: Li-Ren
authors.initials: LR
authors.lastname: Chang
authors.affiliation: Department of Plastic Surgery, E-DA Hospital, Kaohsiung 824, Taiwan, R.O.C.
authors.forename: Guan-Ming
authors.initials: GM
authors.lastname: Feng
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung 802, Taiwan, R.O.C.
authors.forename: Shu-Ting
authors.initials: ST
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung 802, Taiwan, R.O.C.
authors.forename: Chien-Yan
authors.initials: CY
authors.lastname: Hsieh
authors.affiliation: Department of Plastic Surgery, E-DA Hospital, Kaohsiung 824, Taiwan, R.O.C.
authors.forename: Seng-Feng
authors.initials: SF
authors.lastname: Jeng
authors.affiliation: Division of Plastic Surgery, Kaohsiung Armed Forces General Hospital Zuoying Branch, Kaohsiung 813, Taiwan, R.O.C. ; Department of Surgery, National Defense Medical Center, Taipei 114, Taiwan, R.O.C.
authors.forename: Wen-Shyan
authors.initials: WS
authors.lastname: Huang
keywords: aquaporin; hypertonic stress; intestinal epithelial cells; ischemia/reperfusion; mannitol