OBJECTIVETo investigate the effects of mitogen activated protein kinase (MAPK) signal transduction pathways on heat shock protein 70 (HSP70) gene expression in endothelial cells exposed to benzo(a)pryene (BaP).

METHODSPorcine aortic endothelial cells were pre-treated or by PD98059 (10 micro mol/L) or SB203580 (20 micro mol/L) for 1 hour, then treated with different concentrations of BaP (0, 0.1, 0.5, 1.0, 5.0 and 10.0 micro mol/L) for 24 hours respectively;Expression levels of three phosphorylated MAPKs [extracellular signal regulated protein kinase (ERK), c-Jun amino-terminal kinase (JNK), and p38] and HSP70 were determined by Western-blot.

RESULTSThe three phosphorylated MAPKs expressional levels especially p-ERK1 had different extents of changes with dose-response relationship under BaP exposure. BaP inhibited the expression of HSP70, which significantly decreased in medium and high dose group (>or= 1.0 micro mol/L) but did not decrease in control group (P < 0.05). Although the inhibitor of ERK (PD98059) could partly weaken the inhibited effects of BaP on HSP70 expression, HSP70 expression levels of endothelial cells pre-treated with PD98059 were still significantly lower than that of control cells (P < 0.05).

CONCLUSIONERK1 pathway might play some roles in HSP70 gene expression in endothelial cells exposed to BaP, and other unknown signal pathways might also have some effects on this process.

Animals ; Benzo(a)pyrene ; toxicity ; Blotting, Western ; Dose-Response Relationship, Drug ; Endothelial Cells ; drug effects ; metabolism ; Enzyme Inhibitors ; pharmacology ; Flavonoids ; pharmacology ; HSP70 Heat-Shock Proteins ; analysis ; Imidazoles ; pharmacology ; JNK Mitogen-Activated Protein Kinases ; MAP Kinase Kinase 4 ; Mitogen-Activated Protein Kinase Kinases ; analysis ; Mitogen-Activated Protein Kinases ; analysis ; antagonists & inhibitors ; Pyridines ; pharmacology ; Signal Transduction ; physiology ; Swine ; p38 Mitogen-Activated Protein Kinases

PURPOSE: Based on the close relationship between histamine and interleukin 6 (IL-6), we hypothesized that histamine may regulate the production of cytokines, such as IL-6, during allergic inflammation. Here, we examined the role of histamine in IL-6 production and histamine receptor activity in nasal fibroblasts, along with the mechanisms underlying these effects. METHODS: Experiments were performed using nasal fibroblasts from 8 normal patients. RT-PCR was used to identify the major histamine receptors expressed in nasal fibroblasts. Fibroblasts were then treated with histamine with or without histamine-receptor antagonists, and monitored for IL-6 production using an ELISA. Four potential downstream signaling molecules, p38, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and NF-kappaB, were evaluated by Western blot, and a luciferase reporter assay. RESULTS: Elevated expression was seen for all histamine receptors, with IL-6 protein levels increasing significantly following histamine stimulation. Among the histamine-receptor specific antagonists, only the H1R antagonist significantly decreased IL-6 production in histamine-stimulated nasal fibroblasts. Histamine increased the expression level of phosphorylated p38 (pp38), pERK, and pJNK, as well as NF-kappaB induction. The H1R antagonist actively suppressed pp38 and NF-kappaB expression in histamine-induced nasal fibroblasts, but not pERK and pJNK. The p38 inhibitor strongly attenuated IL-6 production in histamine-stimulated nasal fibroblasts. CONCLUSIONS: The data presented here suggest that antihistamines may be involved in the regulation of cytokines, such as IL-6, due to the role of histamine as an inflammatory mediator in nasal fibroblasts.
Blotting, Western ; Cytokines ; Enzyme-Linked Immunosorbent Assay ; Fibroblasts* ; Histamine Antagonists ; Histamine* ; Humans ; Inflammation ; Interleukin-6* ; JNK Mitogen-Activated Protein Kinases ; Luciferases ; NF-kappa B* ; Nose ; Phosphotransferases ; Receptors, Histamine

OBJECTIVETo investigate the effect of SP600125, a specific c-jun N-terminal protein kinase (JNK) inhibitor, on Staphylococcus aureus (S. aureus)-induced U937 cell death and the underlying mechanism.

METHODSThe human monocytic U937 cells were treated with S. aureus at different time with or without SP600125. Cell apoptosis was analyzed by flow cytometry. JNK, Bax, and caspase-3 activities were detected by Western blotting.

RESULTSS. aureus induced apoptosis in cultured U937 cells in a time-dependent manner. Expression of Bax and phospho-JNK significantly increased in S. aureus-treated U937 cells, and the level of activated caspase-3 also increased in a time-dependent manner. Inhibition of JNK with SP600125 significantly inhibited S. aureus-induced apoptosis in U937 cells.

CONCLUSIONSS. aureus can induce apoptosis in U937 cells by phosphorylation of JNK and activation of Bax and caspase-3. SP600125 protects U937 cells from apoptosis induced by S. aureus via inhibiting the activity of JNK.

Anthracenes ; pharmacology ; Apoptosis ; physiology ; Caspase 3 ; metabolism ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Macrophages ; cytology ; metabolism ; microbiology ; Mitogen-Activated Protein Kinase 8 ; antagonists & inhibitors ; metabolism ; Mitogen-Activated Protein Kinase 9 ; antagonists & inhibitors ; metabolism ; Phosphorylation ; drug effects ; Protein Kinase Inhibitors ; pharmacology ; Signal Transduction ; physiology ; Staphylococcus aureus ; physiology ; U937 Cells ; bcl-2-Associated X Protein ; metabolism

NMDA-induced excitotoxicity cause severe neuronal damage including apoptosis and necrosis. The present study was aimed to evaluate the proportion of NMDA-induced apoptosis of rat cortical neurons and discover signal transduction mechanism. Caspase inhibitor and lactate dehydrogenase (LDH) assay were used to study the NMDA-induced apoptosis. To explore the involved signal pathways, the primary culture of rat cortical neurons were pretreated by the inhibitors of three MAPK pathways, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK. With 2 h of NMDA treatment, cellular apoptosis was measured by caspase-3 activity, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) and Annexin V staining. The results showed that: (1) Caspase-dependent apoptosis accounted for 22.49% in NMDA-induced neuronal death; (2) Pretreatment with p38 MAPK inhibitor SB203580 (10 μmol/L) significantly decreased NMDA-mediated caspase-3 activity by 30.43% (P < 0.05). However, ERK inhibitor PD98059 (20 μmol/L) or JNK inhibitor SP600125 (20 μmol/L) did not influence caspase-3 activity; (3) Pretreatment with SB203580 significantly reduced the number of NMDA-induced TUNEL-positive cells by 33.10% (P < 0.05). PD98059 (20 μmol/L) or SP600125 (20 μmol/L) did not show obvious effect; (4) Pretreatment with SB203580 (10 μmol/L) significantly reduced the number of NMDA-induced early apoptotic neurons by 55.56% (P < 0.05). Also, SP600125 (20 μmol/L) significantly decreased the amount of late apoptotic/dead cells by 67.59% (P < 0.05). There was no effect of PD98059 (20 μmol/L). These results indicate that: (1) NMDA induces neuronal apoptosis besides necrosis; (2) p38 MAPK, but not JNK and ERK, is involved in NMDA-induced neuronal apoptosis, and inhibition of the apoptotic signaling pathway contributes to neuroprotection; (3) JNK activation might contribute to NMDA-induced neuronal necrosis rather than apoptosis.
Animals ; Anthracenes ; pharmacology ; Apoptosis ; Caspase 3 ; metabolism ; Cells, Cultured ; Extracellular Signal-Regulated MAP Kinases ; antagonists & inhibitors ; Imidazoles ; pharmacology ; JNK Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; MAP Kinase Signaling System ; N-Methylaspartate ; pharmacology ; Neurons ; cytology ; Primary Cell Culture ; Pyridines ; pharmacology ; Rats ; p38 Mitogen-Activated Protein Kinases ; antagonists & inhibitors

Amyloid beta (Aβ) precursor protein (APP) is a key protein in the pathogenesis of Alzheimer's disease (AD). Both APP and its paralogue APLP1 (amyloid beta precursor-like protein 1) have multiple functions in cell adhesion and proliferation. Previously it was thought that autophagy is a novel beta-amyloid peptide (Aβ)-generating pathway activated in AD. However, the protein proteolysis of APLP1 is still largely unknown. The present study shows that APLP1 is rapidly degraded in neuronal cells in response to stresses, such as proteasome inhibition. Activation of the endoplasmic reticulum (ER) stress by proteasome inhibitors induces autophagy, causing reduction of mature APLP1/APP. Blocking autophagy or JNK stress kinase rescues the protein expression for both APP and APLP1. Therefore, our results suggest that APP/APLP1 is degraded through autophagy and the APLP1 proteolysis is mainly mediated by autophagy-lysosome pathway.
Amyloid beta-Protein Precursor ; genetics ; metabolism ; Animals ; Autophagy ; Cell Line ; Endoplasmic Reticulum ; metabolism ; JNK Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; metabolism ; Leupeptins ; pharmacology ; Mice ; Neurons ; cytology ; metabolism ; Proteasome Endopeptidase Complex ; metabolism ; Proteasome Inhibitors ; Protein Stability ; Rats

To explore the effect of ginsenoside Rb1 on JNK/p38 MAPK in the process of beta-amyloid peptide (25-35) -induced tau protein hyperphosphorylation, Western blotting and immunocytochemical stain were performed to observe the tau protein phosphorylation and the expression of JNK/p38 MAPK. The level of tau protein phosphorylation in the sites of Ser396 , Ser199/202 and Thr205 increased after rat cortical neurons exposed to 20 micromol x L(-1) Abeta25-35, meanwhile the level of JNK/p38 MAPK also increased after Abeta25-35 treatment for 12 h. Pretreatment with several doses of ginsenoside Rbl markedly attenuated tau protein hyperphosphorylation and the expression of JNK/p38 MAPK. Ginsenoside Rbl markedly attenuated tau protein hyperphosphorylation through JNK/p38 MAPK pathway.
Amyloid beta-Peptides ; antagonists & inhibitors ; Animals ; Cells, Cultured ; Cerebral Cortex ; cytology ; metabolism ; Ginsenosides ; isolation & purification ; pharmacology ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Neurons ; metabolism ; Panax ; chemistry ; Peptide Fragments ; antagonists & inhibitors ; Phosphorylation ; Plants, Medicinal ; chemistry ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases ; metabolism ; tau Proteins ; metabolism

Ultraviolet B (UVB) irradiation of skin induces an acute inflammation. Cyclooxygenase-2 (COX-2) protein plays key roles in acute inflammation in UVB-irradiated keratinocyte cell line HaCaT. Recently, curcumin has been regarded as a promising anti-inflammatory agent due to its ability to inhibit COX-2 expression. However, it remains largely unknown whether curcumin inhibits the UVB-induced COX-2 expression in HaCaT cells. This study was undertaken to clarify the effect of curcumin on the expression of COX-2 in UVB- irradiated HaCaT cells and further determined the molecular mechanisms associated with this process. In this study, we have found that the expression of COX-2 mRNA and protein were up-regulated in UVB-irradiated HaCaT cells in a dose- and time-dependent manner. Interestingly, treatment with curcumin strongly inhibited COX-2 mRNA and protein expressions in UVB-irradiated HaCaT cells. Notably, there was effective inhibition by curcumin on UVB-induced activations of p38 MAPK and JNK in HaCaT cells. The DNA binding activity of AP-1 transcription factor was also markedly decreased with curcumin treatment in UVB-irradiated HaCaT cells. These results collectively suggest that curcumin may inhibit COX- 2 expression by suppressing p38 MAPK and JNK activities in UVB-irradiated HaCaT cells. We propose that curcumin may be applied as an effective and novel sunscreen drug for the protection of photoinflammation.
Curcumin/*pharmacology ; Enzyme Activation/drug effects/radiation effects ; Enzyme Inhibitors/pharmacology ; Humans ; JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors/*metabolism ; Keratinocytes/cytology/*drug effects/*radiation effects ; Prostaglandin-Endoperoxide Synthase/*metabolism ; Research Support, Non-U.S. Gov't ; Transcription Factor AP-1/*metabolism ; Ultraviolet Rays ; p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors/*metabolism

OBJECTIVETo investigate the role and mechanism of c-Jun N-terminal kinase (JNk) inhibitor (SP600125) in amelioration of insulin resistance after scald.

METHODSTwenty-four Sprague-Dawley rats were randomized into sham (the process of scald was mimicked by water at room temperature) , scald, scald and SP600125 groups. The rats were inflicted with 30% TBSA full-thickness scald in the latter two groups. Euglycemic-hyperinsulinemic glucose clamp experiment was carried out 4 days after scald. SP600125 was administered to the rats in scald and SP600125 2 hrs before Euglycemic-hyperinsulinemic glucose clamp was performed. Changes in the phospho-Serine307 and phospho-tyrosine of IRS-1 activity, as well as expression of phospho-JNK in muscles were determined.

RESULTSEuglycemic-Hyperinsulinemic Glucose Clamps experiment showed that the infusion rate of 100 g/L glucose in sham, scald, scald and SP600125 groups were (12. 33 +/-0. 42) , (6. 61 +/-0. 27) , (11. 11 +/-0. 68) mgx kg(-1) x min(-1) , respectively ( P <0.01). The level of IRS-1 Serine307 phosphorylation and JNK activity in muscles were significantly increased, while insulin-induced tyrosine phosphorylation of IRS-1 decreased markedly after scald. Compared with scald group, the level of IRS-1 Serine307 phosphorylation and JNK activity in scald and SP600125 group were decreased but tyrosine phosphorylation was elevated.

CONCLUSIONSP600125 can partially ameliorate insulin resistance after scald by inhibition of JNK activation, and decrease the level of IRS-1 phospho-serine307.

Animals ; Anthracenes ; pharmacology ; Burns ; complications ; metabolism ; Hyperinsulinism ; etiology ; Insulin ; metabolism ; Insulin Receptor Substrate Proteins ; metabolism ; Insulin Resistance ; JNK Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; Phosphorylation ; Protein Kinase Inhibitors ; pharmacology ; Rats ; Rats, Sprague-Dawley

The aim of the present study was to investigate the effect of precursor brain-derived neurotrophic factor (proBDNF) on survival and neurite outgrowth of cultured rat spiral ganglion neurons (SGNs). Spiral ganglions (SG) were collected from postnatal day 5 Sprague Dawley (SD) rats, then enzymatically digested and suspended. Dissociated SGNs were plated on poly-D-lysine/laminin coated eight-well chamber plates and maintained at 37 °C for 4 h to promote the attachment of the neurons. Cultured SGNs were randomly divided into five groups: control group, BDNF group (BDNF 10 ng/mL), C10 group (proBDNF 10 ng/mL), C50 group (proBDNF 50 ng/mL), and C100 group (proBDNF 100 ng/mL). All groups were incubated in a serum-free medium. 48 h after incubation, SGNs were fixed and stained for βIII tubulin. Immunostaining of the cultured SGNs showed that, compared with the control group, the cellular survival of C50 group and C100 group were significantly reduced (P < 0.001). Furthermore, surviving numbers of the three proBDNF-treated groups were all lower than the BDNF group. In order to assess the effect of proBDNF on cell morphology, SGNs were divided into two categories: SGNs with or without neurites. The results demonstrated that proBDNF significantly increased the proportions of SGNs without neurites in C10, C50 and C100 groups compared with that in control group (P < 0.001). In addition, c-Jun N-terminal kinase (JNK) inhibitor, SP600125 (20 μmol/L) significantly increased the surviving number of SGNs in C50 group. These results suggest that proBDNF reduces the survival rate of cultured SGNs and inhibits the sprouting of neurites. Furthermore, the inhibition of JNK signaling attenuates the effect of proBDNF on SGNs survival.
Animals ; Axons ; physiology ; Brain-Derived Neurotrophic Factor ; pharmacology ; Cell Survival ; Cells, Cultured ; JNK Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; MAP Kinase Signaling System ; Neurites ; physiology ; Neurons ; cytology ; Protein Precursors ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Spiral Ganglion ; cytology

PURPOSE: Dexmedetomidine, a full agonist of alpha2B-adrenoceptors, is used for analgesia and sedation in the intensive care units. Dexmedetomidine produces an initial transient hypertension due to the activation of post-junctional alpha2B-adrenoceptors on vascular smooth muscle cells (SMCs). The aims of this in vitro study were to identify mitogen-activated protein kinase (MAPK) isoforms that are primarily involved in full, alpha2B-adrenoceptor agonist, dexmedetomidine-induced contraction of isolated rat aortic SMCs. MATERIALS AND METHODS: Rat thoracic aortic rings without endothelium were isolated and suspended for isometric tension recording. Cumulative dexmedetomidine (10(-9) to 10(-6) M) dose-response curves were generated in the presence or absence of extracellular signal-regulated kinase (ERK) inhibitor PD 98059, p38 MAPK inhibitor SB 203580, c-Jun NH2-terminal kinase (JNK) inhibitor SP 600125, L-type calcium channel blocker (verapamil and nifedipine), and alpha2-adrenoceptor inhibitor atipamezole. Dexmedetomidine-induced phosphorylation of ERK, JNK, and p38 MAPK in rat aortic SMCs was detected using Western blotting. RESULTS: SP 600125 (10(-6) to 10(-5) M) attenuated dexmedetomidine-evoked contraction in a concentration-dependent manner, whereas PD 98059 had no effect on dexmedetomidine-induced contraction. SB 203580 (10(-5) M) attenuated dexmedetomidine-induced contraction. Dexmedetomidine-evoked contractions were both abolished by atipamezole and attenuated by verapamil and nifedipine. Dexmedetomidine induced phosphorylation of JNK and p38 MAPK in rat aortic SMCs, but did not induce phosphorylation of ERK. CONCLUSION: Dexmedetomidine-induced contraction involves a JNK- and p38 MAPK-mediated pathway downstream of alpha2-adrenoceptor stimulation in rat aortic SMCs. In addition, dexmedetomidine-induced contractions are primarily dependent on calcium influx via L-type calcium channels.
Adrenergic alpha-2 Receptor Agonists/*pharmacology ; Animals ; Anthracenes/pharmacology ; Aorta/cytology ; Dexmedetomidine/*pharmacology ; Enzyme Inhibitors/pharmacology ; Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors/physiology ; Flavonoids/pharmacology ; Imidazoles/pharmacology ; JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors/*physiology ; Male ; *Muscle Contraction ; Muscle, Smooth, Vascular/drug effects/enzymology/*physiology ; Protein Isoforms/antagonists & inhibitors/physiology ; Pyridines/pharmacology ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors/physiology