Molecular analysis of AQP2 promoter. I. cAMP-dependent regulation of mouse AQP2 gene .
- Author:
Mi Young PARK
1
;
Yong Hwan LEE
;
Hae Rahn BAE
;
Ryang Hwa LEE
;
Sang Ho LEE
;
Jin Sup JUNG
Author Information
1. Department of Physiology, College of Medicine, Pusan National University, Pusan 602-739, Korea.
- Publication Type:In Vitro ; Original Article
- Keywords:
AQP2 gene;
cAMP;
Collecting duct;
Regulation
- MeSH:
Animals;
Aquaporin 2;
Cell Line;
Embryonic Structures;
Fibroblasts;
Luciferases;
Mice*;
Osmolar Concentration;
Promoter Regions, Genetic
- From:The Korean Journal of Physiology and Pharmacology
1999;3(2):157-164
- CountryRepublic of Korea
- Language:English
-
Abstract:
To determine molecular mechanisms of Aquaporin-CD (AQP2) gene regulation, the promoter region of the AQP2 gene was examined by transiently transfecting a promoter-luciferase reporter fusion gene into mouse renal collecting duct cell lines such as mIMCD-3, mIMCD-K2, and M-1 cells, and NIH3T3 mouse embryo fibroblast cells. PCR-Southern analysis reveals that mIMCD-3 and mIMCD-K2 cells express AQP2, but M-1 and NIH3T3 cells do not, and that the treatment with cpt-cAMP (400 muM) or forskolin/isobutylmethylxanthine (IBMX) increased the AQP2 expression in IMCD cells. In both IMCD and NIH3T3 cells, the constructs containing the promoter of AQP2 gene showed promoter activities, indicating lack of tissue-specific element in the 1.4 kb 5'-flanking region of the mouse AQP2 gene. Luciferase activity in the IMCD cells transfected with the construct containing 5-flanking region showed responsiveness to cpt-cAMP, indicating that the 1.4 kb 5'-flanking region contains the element necessary for the regulatory mechanism by cAMP. The promoter-luciferase constructs which do not have a cAMP-responsible element (CRE) still showed the cAMP responsiveness in IMCD cells, but not in NIH3T3 cells. Increase in medium osmolarity did not affect AQP2 promoter activity in mIMCD-K2 cells. These results demonstrate that AQP2 gene transcription is increased with cAMP treatment through multiple motifs including CRE in the 5'-flanking region of the gene in vitro, and the regulatory mechanism may be important for in vivo regulation of AQP2 expression.
