Role Of JNK Signaling Pathway Research Articles

Prevention of acetaminophen-induced hepatocyte injury: JNK inhibition and GSTA1 involvement

Glutathione S-transferase A1 (GSTA1) is a detoxification enzyme and a sensitive marker for hepatotoxicity. We investigated the effects of JNK inhibition on different degrees of Acetaminophen (APAP)-induced hepatocyte injury and GSTA1 expression. This study aimed to investigate the role of JNK signaling pathway in APAP-induced different degrees of hepatocyte injury and its correlation with GSTA1 by inhibiting the phosphorylation of JNK by SP600125. 6 and 8 mM APAP induced different degrees of hepatocyte injury and apoptosis, both activated JNK signaling pathway. In contrast, JNK inhibitor significantly reduced activation of JNK and c-JUN on exposure to APAP. Meanwhile, the levels of hepatocyte injury, oxidative stress, and apoptosis obviously decreased. Importantly, GSTA1 expression was significantly increased by JNK inhibition. JNK inhibition attenuates APAP-induced hepatocyte injury and oxidative stress and increases GSTA1 expression. Furthermore, GSTA1 may be involved in this signaling pathway for detoxification.

Role of JNK Signaling Pathway in Dexmedetomidine Post-Conditioning-Induced Reduction of the Inflammatory Response and Autophagy Effect of Focal Cerebral Ischemia Reperfusion Injury in Rats.

To investigate the effect of dexmedetomidine post-conditioning on the inflammatory response and autophagy effect of focal cerebral ischemia reperfusion injury in rats, and further to study its potential mechanisms. Water maze was conducted to evaluate spatial learning and memory ability of middle cerebral artery occlusion (MCAO) rats. TTC staining was used to observe the area of cerebral infarction. The expressions of inflammatory factors in serum were detected by ELISA. TUNEL assay, HE staining, and transmission electron microscopy were used to detect the apoptosis of neurons, neuro-cytopathic changes, and the formation of auto-phagosome in hippocampus CA1 region, respectively. The mRNA and protein expression of Beclin-1, Caspase-3, and light chain 3 (LC3) were detected by qRT-PCR and Western blot. Moreover, the activity of C-Jun N-terminal kinase (JNK) pathway was detected by Western blot. The escape latency (EL); cerebral infarction area ratio; positive apoptosis; neuron pathological changes; auto-phagosome numbers; inflammatory factor contents; mRNA and protein expressions of Beclin-1, Caspase-3 and LC3II/I; and the phosphorylation level of JNK were decreased, while the times across platform and the times stayed in the quadrant of the original platform were increased after dexmedetomidine treatment. However, the protective effect of dexmedetomidine on brain injury in MCAO rats was reversed by JNK pathway activator. Dexmedetomidine post-conditioning could improve learning and memory dysfunction caused by MCAO in rats and reduce the inflammatory response and autophagy effect. The mechanism may be related to inhibition of JNK pathway activation.

RNase L Induces Expression of A Novel Serine/Threonine Protein Kinase, DRAK1, to Promote Apoptosis.

Apoptosis of virus-infected cells is an effective antiviral mechanism in addition to interferon induction to establish antiviral state to restrict virus spread. The interferon-inducible 2′–5′ oligoadenylate synthetase/RNase L pathway results in activation of RNase L in response to double stranded RNA and cleaves diverse RNA substrates to amplify interferon induction and promote apoptosis. Here we show that RNase L induces expression of Death-associated protein kinase-Related Apoptosis-inducing protein Kinase 1 (DRAK1), a member of the death-associated protein kinase family and interferon-signaling pathway is required for induction. Overexpression of DRAK1 triggers apoptosis in the absence of RNase L activation by activating c-Jun N-terminal kinase (JNK), translocation of BCL2 Associated X (Bax) to the mitochondria accompanied by cytochrome C release and loss of mitochondrial membrane potential promoting cleavage of caspase 3 and Poly(ADP-Ribose) Polymerase 1 (PARP). Inhibitors of JNK and caspase 3 promote survival of DRAK1 overexpressing cells demonstrating an important role of JNK signaling pathway in DRAK1-mediated apoptosis. DRAK1 mutant proteins that lack kinase activity or nuclear localization fail to induce apoptosis highlighting the importance of cellular localization and kinase function in promoting cell death. Our studies identify DRAK1 as a mediator of RNase L-induced apoptosis.

Role of JNK signalling pathway and platelet‑lymphocyte aggregates in myocardial ischemia‑reperfusion injury and the cardioprotective effect of ischemic postconditioning in rats.

In myocardial ischemia‑reperfusion injury (MIRI), increased activity of the c‑Jun N‑terminal kinase (JNK) pathway and the activation of platelets that leads to the formation of platelet‑leukocyte aggregates (PLAs) have been observed. It was hypothesized that ischemic postconditioning in MIRI exerts cardioprotective effects by altering JNK activity, which in turn leads to reduced PLA levels. A total of 60 rats were randomly divided into 6 groups (n=10 for each group): i)Control; ii)ischemia‑reperfusion injury alone; iii)ischemia‑reperfusion with postconditioning (PostC group), iv)treatment with the JNK inhibitor‑SP600125; v)postC and treatment with anisomycin; and vi)treatment with the JNK activator‑anisomycin. Subsequently, the levels of PLA, infarct size, myocardial injury markers (creatinine kinase‑muscle/brain and troponin I) and were measured. Western blotting was used to determine the protein expression of phosphorylated‑JNK. MIRI led to increased myocardial infarct size that was associated with raised troponin I and creatine kinase‑muscle/brain. At different time points of MIRI, the level of PLA gradually increased. Compared with the injury‑reperfusion group, the level of PLA in the PostC and Inhibitor‑JNK groups was significantly reduced at 60min and 3h following reperfusion. MIRI was able to increase the expression of phosphorylated JNK. These effects were significantly reduced by ischemic postC or by treatment with SP600125. By contrast, the addition of anisomycin attenuated these protective effects. JNK is a critical mediator of MIRI. Ischemic postC can reduce the level of PLA during reperfusion by inhibiting the phosphorylation of JNK MAPK, thereby reducing MIRI. Pharmacological inhibition and activation of JNK can improve and reduce cardioprotective effects, respectively. These results explained the mechanism of the cardioprotection of postC and provided novel insight and target for the therapeutic strategy of MIRI.

Role of JNK signaling pathway in hyperoxia-induced expression of connective tissue growth factor in A549 cells

Objective To investigate the role of c-Jun N-terminal kinase(JNK)signaling pathway in hyperoxia-induced expression of connective tissue growth factor(CTGF)in A549 cells. Methods The cultured A549 cells were seeded in 6-well culture plates at a density of 1×105 cells/ml(0.5 ml/well, 24 wells in total)and were randomly divided into 4 groups(n=6 each)using a random number table: control group(group C); 95% oxygen group(group 95% O2); room air plus SP600125(JNK inhibitor)group(group C+ SP); 95% oxygen plus SP600125 group(group 95% O2+ SP). SP600125 5 μmol/L was added to each well in C+ SP and 95% O2+ SP groups.The A549 cells were incubated for 48 h in an incubator filled with room air(C and C+ SP groups)or 95% oxygen(95% O2 and 95% O2+ SP groups). The expression of phosphorylated JNK(p-JNK)and CTGF mRNA was determined using Western blot and real-time reverse transcriptase polymerase chain reaction, respectively. Results Compared with group C, no significant change was found in the expression of p-JNK and CTGF mRNA in group C+ SP(P>0.05), and the expression of p-JNK and CTGF mRNA was significantly up-regulated in group 95% O2(P<0.05). Compared with group 95% O2, the expression of p-JNK and CTGF mRNA was significantly down-regulated in group 95% O2+ SP(P<0.05). Conclusion JNK signaling pathway activation is involved in up-regulation of hyperoxia-induced CTGF mRNA expression in A549 cells. Key words: Oxygen; Epithelial cell; Pulmonary alveoli; JNK mitogen-activated protein kinases; Connective tissue growth factor

Role of JNK signaling pathway in paclitaxel-induced apoptosis in hippocampal neurons of rats: the relationship with NF-κB pathway

Objective To evaluate the role of c-Jun N-terminal kinase(JNK)signaling pathway in paclitaxel-induced apoptosis in hippocampal neurons of rats, and the relationship with nuclear factor kappa B(NF-κB)pathway. Methods The primarily cultured hippocampal neurons were seeded in 96-well plate at a density of 1×106 cells/ml(200 μl/hole), and were randomly divided into 4 groups(n=8 each)using a random number table: control group(C group), paclitaxel group(P group), JNK inhibitor SP600125 group(S group), and SP600125 + paclitaxel group(S+ P group). Paclitaxel 2 ml(1 μmol/L)was added to group P. SP600125 2 ml(10 μmol/L)was added to group S. In group S+ P, SP600125 2 ml(10 μmol/L)was added, the cell were then incubated for 1 h, and then paclitaxel 2 ml(1 μmol/L)was added.The cells were then incubated for 24 h. At 24 h of incubation, the apoptosis in hippocampal neurons was detected by flow cytometry, and the expression of NF-κB p65 was measured by Western blot.The apoptosis rate was calculated. Results Compared with group C, the apoptosis rate was significantly increased, and the expression of NF-κB p65 was up-regulated in P and S+ P groups, and the apoptosis rate was significantly decreased, and the expression of NF-κB p65 was down-regulated in group S(P<0.05). Compared with group P, the apoptosis rate was significantly decreased, and the expression of NF-κB p65 was down-regulated in group S+ P(P<0.05). Conclusion JNK signaling pathway mediates paclitaxel-induced apoptosis in hippocampal neurons of rats, and the mechanism is likely related to inhibition of NF-κB pathway activation. Key words: Paclitaxel; Neurons; Hippocampus; Apoptosis; JNK mitogen-activated protein kinases; NF-κB

Role of JNK signaling pathway in dexmedetomidine-induced reduction of spinal neurotoxicity induced by lidocaine in rats

Objective To evaluate the role of C-Jun N-Terminal kinase(JNK)signaling pathway in dexmedetomidine-induced reduction of spinal neurotoxicity induced by lidocaine in rats. Methods Seventy-two adult male Sprague-Dawley rats, weighing 280–320 g, in which intrathecal catheters were successfully implanted without complications, were randomly divided into 6 groups(n=12 each)using a random number table: control group(group C); SP600125(JNK signaling pathway blocker)group(group SP); dexmedetomidine group(group D); lidocaine group(group L); dexmedetomidine+ lidocaine group(group DL); SP600125+ lidocaine group(group SPL). Dimethyl sulfoxide(DMSO)20 μl was injected intrathecally in group C. SP600125 30 μg and 10% lidocaine 20 μl were injected intrathecally in SP and L groups, respectively.At 20 min after intrathecal injection of 10% lidocaine, dexmedetomidine 75 μg/kg was injected intraperitoneally in group DL, and SP600125 30 μg was injected intrathecally in group SPL.Dexmedetomidine 75 μg/kg was injected intraperitoneally in group D. The mechanical paw withdrawal threshold(MWT)and thermal paw withdrawal latency(TWL)were measured before intrathecal catheters were implanted(T0), before intrathecal administration(T1), and at 4, 8 and 12 h and 1, 2, 3, 4, 5 and 6 days after intrathecal administration(T2-10). At 24 h after intrathecal administration, 6 rats randomly selected from each group were sacrificed.The lumbar segment(L4-5)of the spinal cord was removed for detection of cell apoptosis(by TUNEL)and phosphorylated JNK(p-JNK)expression(by Western blot). The apoptotic index was calculated. Results Compared with group C, no significant change was found in the MWT, TWL, apoptotic index and expression of p-JNK in SP and D groups(P>0.05), the MWT at T2-8 in group L, at T2-6 in group DL and at T2-5 in group SPL were significantly increased, the TWL at T2-8 in group L, at T2-5 in group DL and at T2-4 in group SPL were prolonged, and the apoptotic index and expression of p-JNK were increased in DL, SPL and L groups(P<0.05). Compared with group L, the MWT was significantly decreased, and the TWL was shortened at T2-8, and the apoptotic index and expression of p-JNK were decreased in DL and SPL groups(P<0.05). Conclusion The mechanism by which dexmedetomidine mitigates spinal neurotoxicity induced by lidocaine is related to inhibited activation of JNK signaling pathway in rats . Key words: JNK mitogen-activated prorein kinaese; Lidocaine; Dexmedetomidine; Spinal cord; Drug toxicity

Abstract 1941: Distinct roles of c-Jun N-terminal kinase (JNK) isoforms in skin cancer

Abstract The c-Jun-N-terminal kinases (JNKs), are activated by stress, growth factors and cytokines, and are encoded by three separate genes (JNK 1, 2, and 3), with 10 total isoforms. Our published data has demonstrated that off-target effects on JNK signaling by BRAF inhibitors (BRAFi) are important for the induction of cutaneous squamous carcinoma (cuSCC). Overexpression of JNK2, has been found to promote transformation of keratinocytes, also suggesting an important role of JNK signaling pathway in promoting tumor development. However, it is still unclear how different JNK isoforms, especially ubiquitously expressed JNK1 and JNK2, really function in skin cancer. To delineate the specific roles of JNK1 and JNK2, we expressed C116S mutants, which rendered them insensitive to the pan-JNK inhibitor JNK-IN-8, without affecting their activity. Wild-type and mutant JNK1 and JNK2 were transduced into cuSCC (SRB1) and keratinocyte (HaCaT) cell lines and application of JNK-IN-8 enabled chemical-genetic dissection of JNK1 and JNK2 activity. JNK-IN-8 significantly attenuated UV-induced apoptosis by 80-90% in SRB1 and HaCat cells overexpressing WT JNK1, WT JNK2 or C116S JNK2 mutant compared to vehicle control while having only a slight effect (0-10%) on cells overexpressing C116S JNK1 mutant, suggesting JNK1 is the key player in UV- induced apoptosis. This difference served as the basis for a gene expression profiling study in which we identified differentially expressed genes regulated by JNK1 vs. JNK2. We also showed that the Leucine-zipper and sterile-α motif kinase (ZAK), which is a MAP3K, is an important upstream activator of JNK-mediated UV-induced apoptosis in skin cancer. To probe how ZAK activates JNK signaling, we knocked down ZAK in SRB1 and HaCaT cells with lentiviral shRNA. Following UV exposure, we found that both JNK1 and JNK2 activation occurred with JNK1 activity peaking within 6 hours and JNK2 activity sustained over 24 hours. In ZAK knockdown cells, JNK1 activation was selectively suppressed, suggesting that ZAK preferentially activates JNK1 in this context. In conclusion, our results indicate that JNK signaling pathway, part of which is regulated by ZAK, plays a critical role in skin cancer. JNK1 and JNK2 exert opposing influences that center on the regulation of apoptosis and cell proliferation in skin cancer. Citation Format: Lili Du, Tinghu Zhang, Tamer Kaoud, Nathanael Gray, Kevin Dalby, Kenneth Y. Tsai. Distinct roles of c-Jun N-terminal kinase (JNK) isoforms in skin cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1941. doi:10.1158/1538-7445.AM2015-1941

Abstract 2328: COX-2 induce mediated multidrug resistance by activating JNK signal transduction pathway in colorectal cancer

Abstract Chemotherapy is an important therapeutic option for most cancer patients; however, drug resistance causes the failure of chemotherapy and becomes a major obstacle for successful chemotherapy. The overexpression of P-gp has been associated with the resistance to a wide range of anticancer drugs. In the present study, drug-sensitive and multidrug resistant MDR colon carcinoma cell lines were used to examine the role of JNK signaling pathway in P-gp-mediated MDR associated with COX-2. We have found that sp600125, a JNK inhibitor or NS-398, a COX-2 inhibitor, reduced the degree of MDR in MDR cells. This phenomenon was accompanied by a significant decrease in gene level of ABCB1 and protein level of P-gp in MDR cells. In contrast, addition of a JNK inhibitor had no significant effect on the expression of COX-2. Interestingly, inhibition of COX-2 activity led to a decreased level of p-c-Jun at Ser63/73 due to JNK activation. In addition, there is an overexpression of p-c-Jun in MDR cells transfected with recombinant vector pGL3-Basic-COX-2 promoter. Moreover, the intracellular vincristine accumulation significantly increased with treatment of sp600125, or NS-398. In conclusion, our study has provided the first direct evidence that COX-2 induced up-regulation of P-gp in MDR cells, which was associated with an enhanced activity of the c-Jun phosphorylation at Ser63/73. Our findings may facilitate the development of novel antitumor drugs that are more effective against both chemosensitive and MDR cells. Note: This abstract was not presented at the meeting. Citation Format: Qi Li, Hua Sui. COX-2 induce mediated multidrug resistance by activating JNK signal transduction pathway in colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2328. doi:10.1158/1538-7445.AM2014-2328

Effect of sevoflurane preconditioning on autophagy after traumatic brain injury in rats: the role of JNK signaling pathway

Objective To investigate the effects of sevoflurane preconditioning on autophagy after traumatic brain injury (TBI) in rats and the role of C-Jun N-terminal kinase (JNK) signaling pathway.Methods Sixty adult male Sprague-Dawley rats,weighing 220-250 g,were randomly divided into 4 groups (n =15 each) using a random number table:sham operation group (group S),group TBI,TBI + sevoflurane preconditioning group (group TBI + Sevo) and TBI + sevoflurane preconditioning + JNK inhibitor SP600125 group (group TBI + Sev + SP).TBI models were established using Feeney' s method.In TBI + Sev and TBI + Sev + SP groups,the rats inhaled 2.4％ sevoflurane for 30 min once a day for 4 concecutive days,and TBI was produced at 24 h after the end of sevoflurane preconditioning.In TBI + Sev + SP group,SP600125 (6 mg/kg) was injected intrapetitoneally at 30 min after TBI.Five rats were chosen at day 1,3,and 7 after TBI,and neurological deficit score (NDS) was measured.The rats were then sacrificed and brains were removed to measure brain water content,expression of LC3 lⅡ and Beclin-1 mRNA (using PCR),and expression of LC3 Ⅱ,Beclin-1,JNK and phosphorylated JNK (p-JNK) (by Western blot).Results Compared with group S,brain water content and NDS were significantly increased,and the expression of LC3 Ⅱ and Beclin-1 protein and mRNA,JNK,and p-JNK was up-regulated in the other three groups.Brain water content and NDS were significantly decreased,and the expression of LC3 Ⅱ and Beclin-1 protein and mRNA,JNK,and p-JNK was down-regulated in TBI + Sev and TBI + Sev + SP groups as compared with group TBI,and in TBI + Sev + SP group as compared with TBI + Sev group.Conclusion The mechanism by which sevoflurane preconditioning mitigates TBI is related to inhibiton of activation of JNK signaling pathway and decreased autophagy in rats. Key words: Anesthetics, inhalation ; Craniocerebral trauma ; Autophagy ; Mitogen-activated protein kinases

Microbiota enhances intestinal immunity through JNK/ROS pathways (MUC4P.838)

Abstract Microbiota maintains normal mucosal immunity through complex mechanisms. To examine the role of JNK signaling pathway in microbiota-related gut immunity, we assessed the microflora in ileal lumen and mucosa, the antibacterial protein expression, and the RORγt cells of lamina propria in WT and JNK-/- mice. The bacterial counts in ileal lumen and mucosa show a significant decrease of Lacobacilli in JNK-/- mice. Moreover, JNK-/- mice demonstrated a significant decrease of RORγt cells in lamina propria and an increased translocation of Klebsiella pneumoniae to the portal vein as well as blood. The generation of reactive oxygen species (ROS) in intestinal mucosa was also significantly decreased in JNK-/- mice as detected by using 2',7'-dichlorodihydrofluorescein diacetate. Oral supplementation of fructooligosaccharides (FOS) or L-NAME but not D-NAME increased the production of ROS, IL-1β, IL-23 as well as RORγt cells in intestine, and decreased the translocation of K. pneumoniae in JNK-/- mice compared to WT mice. N-Acetylcysteine, an antioxidant, treatment inhibited ROS production and reversed the effect of FOS on intestinal immunity in JNK-/- mice. Collectively, JNK pathway plays an important role in microbiota-induced intestinal immunity through the induction of ROS generation, and FOS or iNOS inhibitor increase the numbers of RORγt cells and the expression of IL-1β as well as IL-23 in JNK-/- mice through enhanced production of ROS.

Comparative analysis of the role of JNK signaling pathway in regulating cell proliferation and apoptosis of rat liver regeneration and rat acute hepatic failure

To compare the role of JNK signaling pathway in rat liver regeneration (LR) and in rat acute hepatic failure (AHF) occurrence at the gene transcription level, Rat Genome 230 2.0 array was used to detect the gene expression profiles of the two processes, and bioinformatics and systems biology methods were applied to analyze the physiological activities uncovered by their gene expression profiles in this study. The results showed that 240 genes were included in the array above, though there were 302 genes related to forty two paths of JNK signaling pathway. Array detection results demonstrated that 52 genes were significantly expressed during LR, 20 genes in AHF occurrence, and 15 genes in both of above two processes. Synergy values of these genes were calculated using a mathematical model established by our lab, which revealed the following. The cell proliferation-promoting effects of paths 1, 16 and paths 1-17 of JNK signaling pathway were stronger than the control at 6-12 h and 72 h of LR, respectively, while the cell proliferation-promoting effects of paths 1-17 and the cell proliferation-inhibiting effects of path 34-35 were weaker at 6h of AHF occurrence. The cell apoptosis-promoting effects of paths 22-23 were much stronger at 6, 12 and 72 h of LR and at 12, 24 h of AHF occurrence. In conclusion, thirty eight paths of JNK signaling pathway regulate cell proliferation and apoptosis in both LR and AHF occurrence.

Role of JNK signaling pathway in sensitivity to radiotherapy of nasopharyngeal carcinoma

Objective The aim of the study was to investigate the effect of c-Jun N-terminal protein kinase (JNK) signaling pathway on influencing the sensitivity to radiotherapy of human nasopharyngeal carcinoma CNE cells.

Effect of N-nitrosodimethylamine on inducible nitric oxide synthase expression and production of nitric oxide by neutrophils and mononuclear cells: the role of JNK signalling pathway

In neutrophils (PMN) and mononuclear cells (PBMC), one of the enzymes responsible for nitric oxide (NO) synthesis is inducible nitric oxide synthase (iNOS). Changes in iNOS expression result from various signalling pathways including the mitogen-activated protein kinase (MAPK) pathway activated by endogenic and exogenic factors. N-nitrosodimethylamine (NDMA) is a xenobiotic with widespread occurrence in human environment and has an effect on cells of the immune system. The aim of this study was to determine the effect of NDMA on iNOS expression and NO production by human PMN and PBMC cells in the light of superoxide anion production by PMN cells. Moreover, the role of JNK and p38 pathways in NO production with involvement of iNOS was studied. Additionally, the function of JNK pathway in generation of superoxide anion was determined. Moreover, nitrotyrosine expression was studied in PMN and PBMC cells in the presence of NDMA. This work shows that NDMA increases iNOS expression and NO production by PMN and PBMC cells. In addition, elevated expression of phospho-JNK and phospho-p38, which are markers of JNK and p38 MAPK pathways activation, were observed. Lower iNOS expression and NO production by neutrophils exposed to extended action of NDMA were observed after application of inhibitor of JNK and p38 pathways. Lower phospho-p38 expression in PMN stimulated by NDMA was found as a result of arresting JNK pathway, whereas, application of inhibitor of p38 pathway resulted in enhanced phospho-JNK expression in PMN and PBMC cells. Increased ability to release superoxide anion by NDMA-stimulated PMN cells was observed. This ability was reduced after the application of inhibitor of JNK pathway. In PMN and PBMC cells exposed to NDMA, an increased expression of nitrotyrosine, which is dependant on JNK and p38 pathways that are activated by this particular xenobiotic, was observed. Generally, increased induction of iNOS related to elevated production of NO by PMN and PBMC cells exposed to NDMA may result in dysfunction of regulation of immunity responses controlled by this molecule in various conditions. Increased expression of nitrotyrosine in PMN and PBMC cells exposed to NDMA may affect their functions in an auto- and/or a paracrine way. Mutual interactions of JNK and p38 MAPK during the induction of iNOS expression in cells exposed to NDMA indicate complex mechanism of induction of iNOS synthase.

Mechanisms underlying the role of JNK signaling pathway in the invasion and metastasis of colon cancer cells

Mechanisms underlying the role of JNK signaling pathway in the invasion and metastasis of colon cancer cells

Interaction of Neisseria meningitidis with human brain microvascular endothelial cells: role of MAP- and tyrosine kinases in invasion and inflammatory cytokine release

Neisseria meningitidis traversal across the blood-cerebrospinal fluid barrier is an essential step in the pathogenesis of bacterial meningitis. We have previously shown that invasion of human brain microvascular endothelial cells (HBMEC) by meningococci is mediated by bacterial outer membrane protein Opc that binds fibronectin, thereby anchoring the bacterium to the integrin alpha 5 beta 1-receptor on the endothelial cell surface. However, subsequent signal transduction mechanisms essential for or regulated by N. meningitidis adhesion and invasion, or HBMEC responses to N. meningitidis are unknown. In this report we investigated the role of c-Jun N-terminal kinases 1 and 2 (JNK1 and JNK2), p38 mitogen-activated (MAP) kinase and protein tyrosine kinases in endothelial-N. meningitidis interaction. Binding of meningococci to HBMEC phosphorylated and activated JNK1 and JNK2 and p38 MAPK as well as their direct substrates c-Jun and MAP kinase activated kinase-2 (MAPKAPK-2), respectively. Non-invasive meningococcal strains lacking opc gene (opc mutants and sequence type 11 complex meningococci) still activated p38 MAPK, however, failed to activate JNK. Inhibition of JNK1 and JNK2 significantly reduced internalization of N. meningitidis by HBMEC without affecting its adherence. Blocking the endothelial integrin alpha 5 beta 1 also decreased N. meningitidis-induced JNK activation in HBMEC. These findings indicate the crucial role of JNK signalling pathway in N. meningitidis invasion in HBMEC. In contrast, p38 MAPK pathway was important for the control of interleukin-6 (IL-6) and IL-8 release by HBMEC. Genistein, a protein tyrosine kinase inhibitor, decreased both invasion of N. meningitidis into HBMEC and IL-6 and IL-8 release, indicating that protein tyrosine kinases, which link signals from integrins to intracellular signalling pathways are essential for both bacterial internalization and cytokine secretion by HBMEC.

Prologation of c-Jun N-terminal kinase is associated with cell death induced by tumor necrosis factor alpha in human chondrocytes.

The aim of this study was to elucidate the role of JNK signaling pathway involved in tumor necrosis factor-alpha (TNF-α)-induced death of chondrocytes. Primary chondrocyte cultures were obtained from human knee osteoarthritis cartilages. First passage chondrocytes were treated with TNF-α and various potentiators, and cell death was measured with MTT assay. C-Jun N terminal kinase (JNK) activation was investigated with the solid phase kinase assay. Expression of apoptosis-related molecule was assayed with Western blot. Chondrocytes were resistant to TNF-α-induced cell death. In contrast, pretreatment with actinomycin D, the phosphatase inhibitor vanadate or MAP kinase phosphatase-1 (MKP-1) inhibitor Ro318220 invariably led to chondrocyte death. While TNF-alpha alone stimulated a single, brief JNK activity, a second JNK peak was observed when the cells were pretreated with actinomycin D. When the cells were pretreated with vanadate or Ro318220, TNF-alpha-induced JNK activation was greatly prolonged, which was associated with the induction of cell death. The expression of Bcl-2 and Mcl-1 decreased significantly in conditions of cell death. In conclusions, our data suggest that chondrocyte death induced by TNF-alpha is associated with sustained JNK activation. This effect may be due to downregulation of TNF-alpha induced phosphatase that inactivates JNK and of Bcl-2 family proteins.

A06 ヒトスジシマカ由来の C6/36 細胞におけるウエストナイルウイルスの感染防御 : ウイルス感染における JNK シグナル伝達の役割

A06 ヒトスジシマカ由来の C6/36 細胞におけるウエストナイルウイルスの感染防御 : ウイルス感染における JNK シグナル伝達の役割