Protein Kinase Activation by Warm And Cold Hypoxia- Reoxygenation in Primary-Cultured Rat Hepatocytes–JNK1/SAPK1 Involvement in Apoptosis

Abstract

Ischemia-reperfusion procedures induced severe hepatic damages owing to different processes related to hypoxia and reoxygenation (H/R) phases, including the consecutive oxygen free radical (OFR) release. Stress-activated protein kinases (SAPKs) could be activated by extracellular stimuli. The aim of this study was to show whether H/R stress conditions could stimulate these kinases, and especially c-jun-N-terminal kinase (JNK 1 /SAPK 1 ), to reveal a potential role of JNK 1 /SAPK 1 in the control of hepatocyte apoptosis. Primary cultured rat hepatocytes, isolated from other liver cells and blood flow, were subjected to warm and cold hypoxiareoxygenation phases mimicking surgical and transplant conditions. The activation status of SAPKs was evaluated by immunoprecipitation or Western-blotting experiments, whereas apoptosis was assessed by measuring caspase activation and internucleosomal DNA fragmentation in vitro and by TUNEL reaction, in vivo. Hypoxia, and especially hypoxia-reoxygenation, significantly increased JNK 1 /SAPK 1 activation in cultured hepatocytes. Either in warm or cold conditions, OFR scavengers (N-Acetylcystein, Di-Phenyleneiodonium, Deferoxamine) decreased this stimulation. Warm ischemia-reperfusion also led to JNK activation. Hypoxia and especially hypoxia-reoxygenation induced programmed cell death in vivo and in vitro. This last phenomenon was inhibited when hepatocytes were treated with SB 202190, which was described as a potent inhibitor of p38 and JNK activities. Altogether, these results confirmed that JNK 1 /SAPK 1 was activated during the hypoxia-reoxygenation process, and that this activity participated in the onset of the apoptosis program. (HEPATOLOGY 2000;32:1029-1036.)

Temporal Activation of p42/44 Mitogen-Activated Protein Kinase and c-Jun N-Terminal Kinase by Acetaldehyde in Rat Hepatocytes and Its Loss after Chronic Ethanol Exposure

“…For example, JNK activation has been linked to both hepatocyte proliferation and apoptosis (Auer et al, 1998;Crenesse et al, 2000). In the present study, both acetaldehyde and ethanol caused robust activation of JNK compared with p42/44 MAPK.…”

Multiphoton microscopy can visualize zonal damage and decreased cellular metabolic activity in hepatic ischemia-reperfusion injury in rats

“…4 Hepatic injury in the transplanted liver results in intracellular adenosine triphosphate (ATP) loss, increased microvascular permeability, inflammatory cell infiltration, and potentially, cell death in the forms of apoptosis and necrosis. 5,6 As a consequence, oxidative stress may lead to graft failure and rejection of the transplanted liver. 6 The reduced form of nicotinamide adenine dinucleotide (NADH) is essential in the production of ATP as an electron donor and a coenzyme.…”

Hypoxia tolerance in mammalian heterotherms

“…JNK/SAPK is one of the major molecules activated by deleterious stimuli such as UV irradiation, hypoxia, free radicals and cytokines. Although, in many cases, the activation of JNK/SAPK leads to cell death, such as is seen in hypoxia-induced apoptosis in hepatocytes and developing brain neurons (Crenesse et al, 2000;Chihab et al, 1998;Kunz et al, 2001), the activation of JNK/SAPK has also been shown to mediate hypoxia-induced expression of basic fibroblast growth factor (bFGF) and hypoxia-induced proliferative responses of fibroblasts (Das et al, 2001;Le and Corry, 1999). More recently, JNK activity has been shown to be essential for late-stage neuritogenesis in N1 cell cultures and suggested to be involved in late stages of functional differentiation such as synaptic connection formation (Xiao and Liu, 2003).…”