title: Natriuretic peptides up-regulate aquaporin 3 in a human colonic epithelial cell line.
abstract: Several specialized channels termed aquaporins (AQPs) facilitate water transport in the gastrointestinal tract. AQP3 localizes to epithelial cells in the human small intestine and colon. However, the regulatory mechanisms responsible for AQP3 function in the gastrointestinal tract are not well understood. To characterize the regulation of AQP3 expression by atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), we studied mRNA expression by Northern blotting, protein expression by Western blotting and DNA binding activity by electrophoretic mobility shift assay (EMSA) in the human colonic epithelial cell line HT-29. We also used several inhibitors to investigate signal transduction. AQP3 mRNA was up-regulated in addition to ANP (>100 nM) and BNP (>10 nM). The expression of AQP3 protein was enhanced at 1 h after the addition of ANP and BNP. The combination of protein kinase-A (PK-A) and protein kinase-G (PK-G) inhibitors completely inhibited the expression of AQP3 mRNA enhanced by ANP or BNP to its basal level. The EMSA of the cyclic-AMP response element (CRE) in HT-29 cells revealed a single band. These results indicate that ANP and BNP up-regulated the expression of AQP3 mRNA and protein, and both PK-A and PK-G dependent pathways mediated this effect.
authors.affiliation: Division of Gastroenterology, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Itoh
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Tsujikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Yasuoka
authors.forename: Tamio
authors.initials: T
authors.lastname: Nakahara
authors.forename: Masaya
authors.initials: M
authors.lastname: Sasaki
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Fujiyama
mesh_terms: D051400:Aquaporin 3; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D045744:Cell Line, Tumor; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006152:Cyclic GMP / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D020097:Natriuretic Peptide, Brain / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: C496027:AQP3 protein, human; D020346:Aquaporins; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D020097:Natriuretic Peptide, Brain; D051400:Aquaporin 3; D009320:Atrial Natriuretic Factor; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP