Activation of ERK or inhibition of JNK ameliorates H(2)O(2) cytotoxicity in mouse renal proximal tubule cells.
BACKGROUND
Our previous studies suggest that the balance between the activation of extracellular signal-regulated kinase (ERK) and the c-Jun N-terminal/stress-activated protein kinase (JNK) might determine cell fate following oxidant injury in vivo.


METHODS
The mouse proximal tubule cell line (TKPTS) was used to study hydrogen peroxide (H(2)O(2))-induced death and survival. The role of ERK and JNK in this process was studied by using adenoviruses that contain either a constitutively active mitogen-activated protein kinase kinase 1 (MEK1) or a dominant-negative JNK. Acridine orange plus ethidium bromide staining was applied to distinguish between viable, apoptotic, and necrotic cells following H(2)O(2) treatment. We analyzed cell cycle events by fluorescence-activated cell sorter (FACS) analysis and the phosphorylation status of ERK and JNK by Western blotting.


RESULTS
TKPTS cells survived a moderate level of oxidative stress (0.5 mM/L H(2)O(2)) via temporary growth arrest, while high dose of H(2)O(2) (1 mM/L) caused extensive necrosis. Survival was associated with activation of both ERK and JNK, while death was associated with JNK activation only. Prior adenovirus-mediated up-regulation of ERK or inhibition of JNK function increased the survival (8- or 7-fold, respectively) of TKPTS cells after 1 mmol/L H(2)O(2) treatment. Interestingly, ERK activation and, thus, survival was associated with growth arrest not proliferation.


CONCLUSIONS
We demonstrate that oxidant injury-induced necrosis could be ameliorated by either up-regulation of endogenous ERK or by inhibition of JNK-related pathways. These results directly demonstrate that the intracellular balance between prosurvival and prodeath mitogen-activated protein kinases (MAPKs) determine proximal tubule cell survival from oxidant injury and reveal possible mediators of survival.
Arany
Istvan
I
Department of Internal Medicine, University of Arkansas for Medical Sciences and Central Arkansas Veteran HealthCare System, Little Rock, Arkansas 72205, USA. iarany@uams.edu
Megyesi
Judit K
JK
Kaneto
Hideaki
H
Tanaka
Sakae
S
Safirstein
Robert L
RL
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation; D005799:Genes, Dominant; D005822:Genetic Vectors; D006861:Hydrogen Peroxide / Q000506:poisoning*; D048031:JNK Mitogen-Activated Protein Kinases; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D016877:Oxidants / Q000506:poisoning*; D010766:Phosphorylation / Q000187:drug effects
D016877:Oxidants; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases