Transcriptional regulation of aquaporin 3 by insulin

✍ Scribed by Shota Higuchi; Masafumi Kubota; Kazuhiro Iguchi; Shigeyuki Usui; Tadashi Kiho; Kazuyuki Hirano

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 222 KB
• Volume: 102
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.21350

✦ Synopsis

Abstract

In the current study, we identified a regulatory factor for the transcription of aquaporin 3 (AQP3) whose expression is repressed by insulin. We constructed a luciferase reporter vector containing bp −1382 to −12 of the 5′‐flanking region of the AQP3 gene for a reporter gene assay and observed that luciferase activity in transfectants with the plasmid decreased on treatment with insulin. Serial deletion constructs revealed two regions responsible for the insulin‐mediated repression, one between bps −1382 and −780, and the other between bps −404 and −82. mRNA expression of forkhead box a2 (Foxa2), the binding site of which was located between bps −1382 and −780, was found to decrease on treatment with insulin. A mutant reporter plasmid with an altered Foxa2‐binding site and siRNA for the Foxa2 sequence counteracted the insulin‐mediated repression of AQP3 transcription. These results suggest that Foxa2 is one of the transcriptional regulators for AQP3 gene expression regulated by insulin. J. Cell. Biochem. 102: 1051–1058, 2007. © 2007 Wiley‐Liss, Inc.