Open AccessTumor necrosis factor α decreases aquaporin 3 expression in intestinal epithelial cells through inhibition of constitutive transcription
Author(s) -
Peplowski Michael A.,
Vegso Andrew J.,
Iablokov Vadim,
Dicay Michael,
Zaheer Raza S.,
Renaux Bernard,
Proud David,
Hollenberg Morley D.,
Beck Paul L.,
MacNaughton Wallace K.
Publication year - 2017
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13451
Subject(s) - tumor necrosis factor alpha , downregulation and upregulation , mapk/erk pathway , gene knockdown , microbiology and biotechnology , transcription factor , aquaporin 3 , biology , chemistry , signal transduction , cell culture , aquaporin , endocrinology , biochemistry , gene , genetics
Inflammatory diseases of the gut are associated with altered electrolyte and water transport, leading to the development of diarrhea. Epithelially expressed aquaporins ( AQP s) are downregulated in inflammation, although the mechanisms involved are not known. We hypothesized that AQP 3 expression in intestinal epithelial cells is altered in intestinal inflammation and that these changes are driven by tumor necrosis factor ( TNF ) α . Human colonic adenocarcinoma ( HT ‐29) cells were treated with TNF α to investigate signaling mechanisms in vitro. AQP 3 expression was assessed by real‐time PCR and radiolabeled glycerol uptake, with select inhibitors and a luciferase reporter construct used to further elucidate intracellular signaling. AQP 3 expression was downregulated in HT ‐29 cells treated with TNF α . Luciferase reporter construct experiments revealed that TNF α downregulated constitutive transcriptional activity of the AQP 3 promoter, and inhibition of MEK / ERK and nuclear factor κ B ( NF ‐ κ B) signaling prevented the decrease in AQP 3 mRNA expression. Constitutive AQP 3 expression was suppressed by specificity protein (Sp) 3, and knockdown of this transcription factor bound to the AQP 3 promoter was able to partially prevent the TNF α ‐induced downregulation of AQP 3. TNF α signals through MEK / ERK and NF ‐ κ B to enhance the negative transcriptional control of AQP 3 expression exerted by Sp3. Similar mechanisms regulate numerous ion channels, suggesting a common mechanism by which both ion and water transport are altered in inflammation.