Selective Activation of the c-Jun N-Terminal Protein Kinase Pathway during 4-Hydroxynonenal-Induced Apoptosis of PC12 Cells

Abstract

The by-product of lipid peroxidation, 4-hydroxynonenal (HNE), was shown to cause apoptosis in PC12 cells. In this study, we investigated the molecular mechanism of HNE-induced apoptosis in these cells. Specifically, we determined the effect of HNE on the activities of mitogen-activated protein (MAP) kinases involved in early signal transduction. Within 15 to 30 min after HNE treatment, c-Jun N-terminal protein kinase (JNK) was maximally activated, before it returned to control level at 1 h post-treatment. In contrast, activities of extracellular signal-regulated kinase and p38 MAP kinase remained unchanged from their baseline levels. Stress-activated protein kinase kinase (SEK1), an upstream kinase of JNK, was also activated within 5 min after HNE treatment and remained activated for up to 60 min. Marked activation of the JNK pathway through SEK1 and apoptosis signal-regulating kinase 1 (ASK1), an upstream kinase of SEK1, was demonstrated by the transient transfection of cDNA for wild-type SEK1 or ASK1 together with JNK into COS-7 cells. Furthermore, significant reductions in JNK activation and HNE-induced cell death were observed when either of the dominant negative mutant of SEK1 or ASK1 was cotransfected with JNK. Pretreatment of PC12 cells with a survival-promoting agent, 8-(4-chlorophenylthio)-cAMP, prevented both the HNE-induced JNK activation and apoptosis. Nonaldehyde, a nontoxic aldehyde, neither caused apoptosis nor JNK activation. Pretreatment of PC12 cells with SB203580, a specific inhibitor of p38 MAP kinase, had no effect on HNE-induced apoptosis. All these data suggest that the selective JNK activation by HNE is critical for the apoptosis of PC12 cells and that the HNE-mediated apoptosis is likely to be mediated through the activation of the ASK1-SEK1-JNK pathway without activation of extracellular signal-regulated kinase or p38 MAP kinase.

γ-Glutamyl transpeptidase is induced by 4-hydroxynonenal via EpRE/Nrf2 signaling in rat epithelial type II cells

“…Levonen et al found that HNE could conjugate with Keap1 in vivo, and the author proposed that this might be the underlying mechanism of HNE-mediated Nrf2 nuclear translocation [72]. Nonetheless, since HNE has been found to activate various signaling pathways including PKC [73][74][75][76][77][78][79], the possibility of Nrf2 phosphorylation by HNE-mediated signaling pathways cannot be excluded.…”

The chemistry of cell signaling by reactive oxygen and nitrogen species and 4-hydroxynonenal

“…The redox regulation of MAPK pathways has been well known (203) and numerous studies have clearly shown that pathophysiological concentration of HNE (1-25 μM) could increase the phosphorylation/activity of the major three MAPK pathways (204)(205)(206)(207)(208)(209)(210).…”

“…In contrast, Song et al reported that HNE more likely activated JNK through targeting upstream kinases. They found that HNE-mediated JNK activation could be abrogated with the dominant-negative inhibition of stress-activated protein kinase kinase 1 (SAPKK1 or SEK1), the upstream kinase of JNK that was also activated by HNE (205). It should be noted however, that modification of the upstream protein kinases by HNE directly has not been demonstrated.…”

MAPK signaling in neurodegeneration: influences of flavonoids and of nitric oxide

“…However, the inhibition of ERK1/2 activation has been shown to protect a mouse neuronal cell line and rat primary cortical neurons form oxidative stress-induced neurotoxicity [1] demonstrating a possible involvement in cell death. The JNK signaling cascade has been reported to be activated by a wide range of different oxidants/reductants including hydrogen peroxide [135,218], lipid peroxidation products [6,191], different types of radiation [63], modulators of intracellular glutathione status [145], peroxynitrite [71], glutamate [180], dithiothreitol, and nitric oxide [152]. Although the links between redox status and MAPK signaling have been known for some time, data demonstrating the molecular basis of such links and identifying the sensors in this redox response are few.…”