title: Fibrogenic stresses activate different mitogen-activated protein kinase pathways in renal epithelial, endothelial or fibroblast cell populations.
abstract: Fibrogenic stresses promote progression of renal tubulointerstitial fibrosis, disparately affecting survival, proliferation and trans-differentiation of intrinsic renal cell populations through ill-defined biomolecular pathways. We investigated the effect of fibrogenic stresses on the activation of cell-specific mitogen-activated protein kinase (MAPK) in renal fibroblast, epithelial and endothelial cell populations. The relative outcomes (cell death, proliferation, trans-differentiation) associated with activation or inhibition of extracellular-regulated protein kinase (ERK) or stress activated/c-Jun N terminal kinase (JNK) were analysed in each renal cell population after challenge with oxidative stress (1 mmol/L H2O2), transforming growth factor-beta1 (TGF-beta1, 10 ng/mL) or tumour necrosis factor-alpha (TNF-alpha, 50 ng/mL) over 0-20 h. Apoptosis increased significantly in all cell types after oxidative stress (P < 0.05). In fibroblasts, oxidative stress caused the activation of ERK (pERK) but not JNK (pJNK). Inhibition of ERK by PD98059 supported its role in a fibroblast death pathway. In epithelial and endothelial cells, oxidative stress-induced apoptosis was preceded by early induction of pERK, but its inhibition did not support a pro-apoptotic role. Early ERK activity may be conducive to their survival or promote the trans-differentiation of epithelial cells. In epithelial and endothelial cells, oxidative stress induced pJNK acutely. Pretreatment with SP600125 (JNK inhibitor) verified its pro-apoptotic activity only in epithelial cells. Transforming growth factor-beta1 did not significantly alter mitosis or apoptosis in any of the cell types, nor did it alter MAPK activity. Tumor necrosis factor-alpha caused increased apoptosis with no associated change in MAPK activity. Our results demonstrate renal cell-specific differences in the activation of ERK and JNK following fibrotic insult, which may be useful for targeting excessive fibroblast proliferation in chronic fibrosis.
authors.affiliation: Department of Molecular and Cellular Pathology, School of Medicine, University of Queensland, Herston Road, Herston, Brisbane 4006, Queensland, Australia.
authors.forename: Betty K
authors.initials: BK
authors.lastname: Pat
authors.forename: Leila
authors.initials: L
authors.lastname: Cuttle
authors.forename: Dianne
authors.initials: D
authors.lastname: Watters
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: David W
authors.initials: DW
authors.lastname: Johnson
authors.forename: Glenda C
authors.initials: GC
authors.lastname: Gobe
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000201:enzymology*; D005347:Fibroblasts / Q000201:enzymology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000166:cytology* / Q000201:enzymology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D008938:Mitosis; D051381:Rats; D013312:Stress, Physiological / Q000201:enzymology*; D019459:Urothelium / Q000166:cytology* / Q000201:enzymology*
chemical_list: D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases