Hypoxia activates c-Jun N-terminal kinase via Rac1-dependent reactive oxygen species production in hepatocytes.
The earliest events after the induction of hemorrhagic shock (HS) are complex and poorly understood. We have recently demonstrated that decreased tissue perfusion and hypoxia during HS lead to an increased phosphorylation of c-Jun N-terminal kinase (JNK) in vivo. The purpose of these investigations was to test the hypothesis that hypoxia activates JNK via Rac1-dependent reactive oxygen species (ROS) signaling. Mice subjected to HS and resuscitated with Ringer's ethyl pyruvate solution (REPS) or N-acetylcysteine (NAC), two scavengers of ROS, demonstrated decreased levels of phosphorylated JNK. Exposure of primary mouse hepatocytes in culture to 1% oxygen led to increased production of ROS and phosphorylation of JNK. The duration of hypoxia correlated with the level of generation of ROS and JNK activation. The phosphorylation of JNK was attenuated in the presence of ROS scavengers or the nicotinamide adenosine dinucleotide phosphate [NDA(P)H] oxidase inhibitor, diphenyleneiodonium (DPI). In addition, hypoxia increased activation of Rac1. Inhibition of Rac1 activation by adenoviral gene transfer of dominant-negative Rac1 (AdRac1) attenuated both ROS formation and JNK activation. Together, these data suggest that ROS generation during hypoxia in the liver directly leads to JNK activation in a Rac1-dependent process.
Mollen
Kevin P
KP
Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
McCloskey
Carol A
CA
Tanaka
Hiroyuki
H
Prince
Jose M
JM
Levy
Ryan M
RM
Zuckerbraun
Brian S
BS
Billiar
Timothy R
TR
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D004789:Enzyme Activation; D005452:Fluoresceins; D022781:Hepatocytes / Q000378:metabolism*; D000860:Hypoxia / Q000503:physiopathology*; D007552:Isotonic Solutions / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000172:deficiency; D051379:Mice; D008810:Mice, Inbred C57BL; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000172:deficiency; D009861:Onium Compounds / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012771:Shock, Hemorrhagic / Q000503:physiopathology*; D013047:Specific Pathogen-Free Organisms; D020830:rac1 GTP-Binding Protein / Q000502:physiology*
D005452:Fluoresceins; D007552:Isotonic Solutions; D008562:Membrane Glycoproteins; D009861:Onium Compounds; D017382:Reactive Oxygen Species; C439503:Ringer's ethyl pyruvate; C065013:2',7'-dichlorodihydrofluorescein; C007517:diphenyleneiodonium; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D048031:JNK Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein; D000111:Acetylcysteine