Korean J Nephrol.  2005 May;24(3):350-357.

Role of Reactive Oxygen Species and Mitogen-activated Protein Kinases in 2, 3, 7, 8-tetrachlorodibinzo-p-dioxin-induced Fibronectin Secretion by MDCK Cells

• Yu MR
• Ha H

Abstract

BACKGROUND
2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD: dioxin) is a potent environmental toxicant that alters various cell function. Both reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPK) mediate dioxin-induced cytotoxicity. Since dioxin was shown to increase renal cell fibronectin secretion in a dose-dependent manner and ROS and MAPK also play roles in fibronectin upregulation in renal cells, the present study examined whether ROS and/or MAPK activation play a role in dioxin-induced fibronectin upregulation in tubular epithelial cells. METHODS: Madin-Darby canine kidney (MDCK) cells were cultured with minimum essential medium (MEM) containing 10% fetal bovine serum. Growth arrested and synchronized MDCK cells by serum deprivation were stimulated with dioxin 1 nM in the presence or absence of extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 50 microM, p38 MAPK inhibitor 100 nM, trolox 500 microM, or taurine 500 microM for up to 48 hours. Dichlorofulorescein (DCF)-sensitive cellular ROS was measured by FACScan and fibronectin in the media and cellular MAPK by a Western blot analysis. RESULTS: Dioxin 1 nM significantly increased cellular ROS and fibronectin in MDCK cells. Antioxidants, trolox and taurine, effectively inhibited dioxin-induced cellular ROS and fibronectin secretion. Dioxin increased phosphorylation of ERK at 5 minutes and P38 MAPK at 48 hours. Dioxin did not affect c-Jun NH2-terminal kinase (JNK) activation for up to 48 hours. Both PD98059 and p38 MAPK inhibitor suppressed dioxin-induced fibronectin secretion by MDCK cells. CONCLUSION: These data suggest that dioxin increases fibronectin secretion by renal distal tubular epithelial cells through ROS and MAPK (ERK and p38 MAPK) and this may lead to renal fibrosis.

Keyword

Dioxin; Tubular epithelial cells; Fibronectin; Reactive oxygen species; Mitogen-activated protein kinases

MeSH Terms

Antioxidants
Blotting, Western
Epithelial Cells
Fibronectins*
Fibrosis
Kidney
Madin Darby Canine Kidney Cells*
Mitogen-Activated Protein Kinases*
p38 Mitogen-Activated Protein Kinases
Phosphorylation
Phosphotransferases
Protein Kinases
Reactive Oxygen Species*
Taurine
Up-Regulation
Antioxidants
Fibronectins
Mitogen-Activated Protein Kinases
Phosphotransferases
Protein Kinases
Reactive Oxygen Species
Taurine
p38 Mitogen-Activated Protein Kinases