NF-kappaB modulates aquaporin-2 transcription in renal collecting duct principal cells.
Renal tubulo-interstitial inflammation is frequently associated with polyuria and urine concentration defects. This led us to investigate the effects of the major pro-inflammatory nuclear factor kappaB (NF-kappaB) pathway on aquaporin 2 (AQP2) expression by the collecting duct. Using immortalized collecting duct principal cells (mpkCCDcl4), we found that, acting independently of vasopressin, activation of NF-kappaB by lipopolysaccharide (LPS) decreased AQP2 mRNA and protein levels in a time- and dose-dependent manner but did not decrease AQP2 mRNA stability. Consistently, constitutively active IkappaB kinase beta decreased AQP2 expression. The LPS-induced decrease in AQP2 mRNA levels was confirmed in rat kidney slices and was reproduced both under conditions of elevated cAMP concentration and V(2) receptor antagonism. Computer analysis of the AQP2 promoter revealed two putative kappaB elements. Mutation of either kappaB element abolished the LPS-induced decrease of luciferase activity in cells expressing AQP2 promoter-luciferase plasmid constructs. Chromatin immunoprecipitation revealed that LPS challenge decreased p65, increased p50 and p52, and had no effect on RelB and c-Rel binding to kappaB elements of the AQP2 promoter. RNA-mediated interference silencing of p65, p50, and p52 confirmed controlled AQP2 transcription by these NF-kappaB subunits. We additionally found that hypertonicity activated NF-kappaB in mpkCCDcl4 cells, an effect that may counteract the Tonicity-responsive enhancer binding protein (TonEBP)-dependent increase in AQP2 gene transcription. Taken together, these findings indicate that NF-kappaB is an important physiological regulator of AQP2 transcription.
Hasler
Udo
U
Service de Néphrologie, Fondation pour Recherches Médicales and University of Geneva, CH-1211, Geneva 4, Switzerland.
Leroy
Valérie
V
Jeon
Un Sil
US
Bouley
Richard
R
Dimitrov
Mitko
M
Kim
Jeong Ah
JA
Brown
Dennis
D
Kwon
H Moo
HM
Martin
Pierre-Yves
PY
Féraille
Eric
E
D000818:Animals; D051399:Aquaporin 2 / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D007249:Inflammation; D007668:Kidney / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051381:Rats; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
D051399:Aquaporin 2; D008070:Lipopolysaccharides; D016328:NF-kappa B