Subcellular redistribution of AQP5 by vasoactive intestinal polypeptide in the Brunner's gland of the rat duodenum

Aquaporin (AQP)5, an exocrine-type water channel, was detected in the rat duodenum by Western blot analysis, and was localized by immunohistochemistry in the secretory granule membranes as well as in the apical and lateral aspects of the plasma membrane of Brunner's gland cells. Incubation of d...

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Published in:American journal of physiology: Gastrointestinal and liver physiology 2005-06, Vol.51 (6), p.G1283-G1291
Main Authors: NAHID PARVIN, Most, KURABUCHI, Shingo, MURDIASTUTI, Kwartarini, CHENJUAN YAO, KOSUGI-TANAKA, Chisato, AKAMATSU, Tetsuya, KANAMORI, Norio, HOSOI, Kazuo
Format: Article
Language:English
Subjects:
Biological and medical sciences
Cells
Fundamental and applied biological sciences. Psychology
Membranes
Peptides
Rodents
Small intestine
Vertebrates: digestive system
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Summary:Aquaporin (AQP)5, an exocrine-type water channel, was detected in the rat duodenum by Western blot analysis, and was localized by immunohistochemistry in the secretory granule membranes as well as in the apical and lateral aspects of the plasma membrane of Brunner's gland cells. Incubation of duodenal slices with vasoactive intestinal polypeptide (VIP) in vitro significantly increased the amount of AQP5 in the apical membrane fraction in a dose- and time-dependent manner with the amount reaching a plateau at 100 nM VIP and becoming near maximal after a 30-s incubation. Protein kinase inhibitors, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7, 50 microM), and N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89; PKA-specific, 1 microM) blocked this increase, but PKC-specific inhibitor calphostin C did not, implying the involvement of PKA but not PKC in this cellular event. Intravenous injection with VIP (40 micro g/kg body wt) provoked dilation of the lumen of the Brunner's gland at 2 and 7 min and increased the staining intensity of AQP5 in the apical and lateral membranes. AQP1 (both nonglycosylated and glycosylated forms) was also found to localize in the apical and basolateral membranes of cells of Brunner's gland. VIP, however, did not provoke any significant change in the AQP1 level in the apical membrane, as judged from the results of the above in vitro and in vivo experiments. These results suggest that VIP induced the exocytosis of granule contents and simultaneously caused translocation of AQP5 but not of AQP1 to the apical membrane in Brunner's gland cells. [PUBLICATION ABSTRACT]
ISSN:0193-1857
1522-1547