Secretin promotes osmotic water transport in rat cholangiocytes by increasing aquaporin-1 water channels in plasma membrane: Evidence for a secretin-induced vesicular translocation of aquaporin-1

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dc.contributor.author Pham, L
dc.contributor.author Marinelli, R A
dc.contributor.author LaRusso, N F
dc.contributor.author Agre, P
dc.date.accessioned 2010-05-06T22:05:09Z
dc.date.available 2010-05-06T22:05:09Z
dc.date.issued 1997-05-16
dc.identifier.citation J Biol Chem. 1997 May 16;272(20):12984-8. doi: 10.1074/jbc.272.20.12984 en
dc.identifier.uri http://jhir.library.jhu.edu/handle/1774.2/34095
dc.description.abstract Although secretin is known to stimulate ductal bile secretion by directly interacting with cholangiocytes, the precise cellular mechanisms accounting for this choleretic effect are unknown. We have previously shown that secretin stimulates exocytosis in cholangiocytes and that these cells transport water mainly via the water channel aquaporin-1 (AQP1). In this study, we tested the hypothesis that secretin promotes osmotic water movement in cholangiocytes by inducing the exocytic insertion of AQP1 into plasma membranes. Exposure of highly purified isolated rat cholangiocytes to secretin caused significant, dose-dependent increases in osmotic membrane water permeability (Pf) (e.g. increased by 60% with 10(-7) M secretin), which was reversibly inhibited by the water channel blocker HgCl2. Immunoblotting analysis of cholangiocyte membrane fractions showed that secretin caused up to a 3-fold increase in the amount of AQP1 in plasma membranes and a proportional decrease in the amount of the water channel in microsomes, suggesting a secretin-induced redistribution of AQP1 from intracellular to plasma membranes. Both the secretin-induced increase in cholangiocyte Pf and AQP1 redistribution were blocked by two perturbations that inhibit secretin-stimulated exocytosis in cholangiocytes, i.e. treatment with colchicine and exposure at low temperatures (20 and 4 degrees C). Our results demonstrate that secretin increases AQP1-mediated Pf in cholangiocytes. Moreover, our studies implicate the microtubule-dependent vesicular translocation of AQP1 water channels to the plasma membrane, a mechanism that appears to be essential for secretin-induced ductal bile secretion and suggests that AQP1 can be regulated by membrane trafficking. en
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dc.description.provenance Made available in DSpace on 2010-05-06T22:05:09Z (GMT). No. of bitstreams: 1 J. Biol. Chem.-1997-Marinelli-12984-8.pdf: 372785 bytes, checksum: 447d0b0d77972216ba81fad0091ce5c9 (MD5) Previous issue date: 1997-05-16 en
dc.language.iso en_US en
dc.publisher American Society for Biochemistry and Molecular Biology en
dc.subject Cell Membrane/metabolism en
dc.subject Secretin/pharmacology en
dc.subject Ion Channels/biosynthesis en
dc.subject Liver/metabolism en
dc.subject Aquaporins en
dc.title Secretin promotes osmotic water transport in rat cholangiocytes by increasing aquaporin-1 water channels in plasma membrane: Evidence for a secretin-induced vesicular translocation of aquaporin-1 en
dc.type Article en

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