CREB mediates ERK-induced survival of mouse renal tubular cells after oxidant stress.
BACKGROUND
We showed that extracellular signal-regulated protein kinase (ERK) is prosurvival during oxidant stress both in the kidney and in cultured mouse proximal tubule (TKPTS) cells and demonstrated concomitant activation of ERK as well as the cyclic adenosine monophosphate (cAMP)-responsive element binding protein (CREB), during survival in vitro. We now show that CREB is a necessary prosurvival target of ERK.


METHODS
Ischemia/reperfusion (I/R) injury was induced in 129Sv mice. Oxidant stress was induced by hydrogen peroxide (H(2)O(2)) in TKPTS cells. Activation of CREB was determined by immunohistochemistry and Western blotting. Inhibition and activation of CREB was achieved by mutant or activated CREB-containing adenoviruses in vitro. The effects of oxidant stress on cell survival, CREB binding, and CREB-mediated transcription was determined by cell counting, gelshift analysis, and luciferase assay, respectively.


RESULTS
I/R activates CREB in the surviving distal nephron segments of the kidney. Inhibition of ERK and CREB abrogates survival after 0.5 mmol/L H(2)O(2) treatment, while overexpression of CREB ameliorates necrotic death caused by 1 mmol/L H(2)O(2). Inhibition of ERK also inhibited CREB activation. Binding of phosphorylated CREB to a CREB oligonucleotide was significantly increased after 0.5 mmol/L H(2)O(2) but decreased after 1 mmol/L H(2)O(2). Similarly, CREB-mediated transcription was significantly increased after 0.5 mmol/L H(2)O(2) treatment, while 1 mmol/L H(2)O(2) inhibited it. Interestingly, transcription from the CREB-driven bcl-2 promoter was unchanged after 0.5 mmol/L but decreased after 1 mmol/L H(2)O(2) treatment in agreement with Western blot studies.


CONCLUSIONS
We show that survival during oxidant stress is mediated through CREB and identification of its downstream targets will reveal important survival pathways.
Arany
Istvan
I
Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA. iarany@uams.edu
Megyesi
Judit K
JK
Reusch
Jane E B
JE
Safirstein
Robert L
RL
D000818:Animals; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D016877:Oxidants; D019253:Proto-Oncogene Proteins c-bcl-2; D006861:Hydrogen Peroxide; D008156:Luciferases; D048049:Extracellular Signal-Regulated MAP Kinases