BACKGROUNDMesangial hypercellularity is a critical early histopathological finding in human and experimental glomerular diseases. Hyperlipidemia and the glomerular deposition of lipoproteins are commonly associated with mesangial hypercellularity and play an important pathobiological role in the development of glomerular diseases. The activated cytoplasmic mitogen-activated protein kinase (MAPK), including mainly extracellular-signal regulated protein kinase (ERK), c-Jun amino-terminal kinase (JNK), and p38, has been thought to translocate into the nucleus and activate various transcription factors and protooncogenes associated with cell growth and proliferation. Lipoprotein (a) (Lp(a)) has been shown to stimulate proliferation of mesangial cells, but the events of Lp(a) signaling have not yet been characterized. The purpose of this study was to investigate the signal transduction pathways involved in Lp(a)-induced cell proliferation and provide an evidence for the participation of Lp(a) in intracellular signaling pathways for mesangial cell proliferation.

METHODSLp(a) was isolated from a patient who was being treated with low density lipoprotein (LDL)-apheresis by density gradient ultracentrifugation and then chromatography. Human mesangial cells (HMCs) were isolated by the sequential sieving technique and stimulated with Lp(a) in different concentration and time course. The DNA synthesis of the cells was measured by [3H] thymidine incorporation for detecting the proliferation. The expression of all the three members of MAPK family, including ERK1/ERK2, JNK, and p38, and their phosphorylation were detected by Western blotting.

RESULTSLp(a) could induce a significant dose-dependent proliferation of HMCs. The 3H-TdR incorporation was 1.64+/-0.31, 1.69+/-0.48, 3.59+/-0.68 (P<0.01), 4.14+/-0.78 (P<0.01), and 4.05+/-0.55 (P<0.01) (10(3) cpm) at the Lp(a) concentration of 0, 5, 10, 25, and 50 microg/ml, respectively. Lp(a) induced an increase in ERK1/ERK2 phosphorylation between 5 and 60 minutes, and in JNK phosphorylation between 15 and 30 minutes after incubating with HMCs, whereas the level of p38 and its phosphorylation was not changed.

CONCLUSIONSLp(a) could stimulate the proliferation of HMCs by activiating the phosphorylation of ERK1/ERK2 and JNK MAPK signaling pathway, whereas p38 pathway had no effect on the Lp(a)-induced HMC proliferation, which indicated that three MAPKs seem to be distinctly involved in the effect. In particular, it also provides the evidence that Lp(a) may act as one of the major endogenous modulators for mitogenic signaling response and cell proliferation within the glomerulus.

Blotting, Western ; Cells, Cultured ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Lipoprotein(a) ; pharmacology ; Mesangial Cells ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Phosphorylation ; drug effects ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo explore the effect of cadmium chloride on the expression and phosphorylation of mitogen-activated protein kinase (MAPK) in normal rat kidney epithelial (NRK) cells.

METHODSThe NRK cells were incubated with cadmium chloride either at respective dose (0, 1, 5, 10, 20, 40 µmol/L) for 24 h or at same dose (10 µmol/L) for respective time (0, 0.5, 1.0, 2.0, 4.0, 8.0 h). Western blotting was applied to test the expression of MAPK in NRK cells (ERK1/2, p38, JNK); and phosphor-specific antibody to detect the phosphorylated MAPK (p-ERK1/2, p-p38, p-JNK).

RESULTSThere was no significant difference in the MAPK expression among the groups either treated with different doses or for different time; however, the level of phosphorylated MAPK was comparatively higher than it in control group. There was an obvious expression of p-ERK1/2 at 1.00 ± 0.06 in the group incubated with 10 µmol/L CdCl(2); and the expression in the 20 µmol/L and 40 µmol/L CdCl(2) group was 2.58 ± 0.11, 2.76 ± 0.23 respectively, which was 1.58 and 1.76 times more than it in 10 µmol/L CdCl(2) group. The differences were statistically significant (F = 827.70, P < 0.01). The respective expression of p-p38MAPK in the 20 µmol/L (2.47 ± 0.20)and 40 µmol/L CdCl(2) group (3.73 ± 0.25)was 1.47 and 2.73 times more than it in control group (1.00 ± 0.02), and the differences were also statistically significant (F = 280.06, P < 0.01). There was a dose-effect relationship of the concentration of cadmium in the expression of p-ERK1/2 (r = 0.919, t = 4.69, P = 0.009) and p-p38MAPK (r = 0.945, t = 5.79, P = 0.004). Additionally, phosphorylated MAPK expressed in a time-dependent manner. The expression of p-ERK1/2 was obvious in the group incubated for 1 h (1.26 ± 0.11), and the respective expression in the 4 h group (1.51 ± 0.07) and 8 h group (3.53 ± 0.23) was 1.5 and 3.5 times of it in the control group (1.00 ± 0.02). The differences were statistically significant (F = 427.82, P < 0.001). The expression of p-p38MAPK increased significantly in 1 h group (1.31 ± 0.07); while the respective expression in 4 h group (3.53 ± 0.32) and 8 h group (4.41 ± 0.38) was 3.5 and 4.4 times of it in control group (1.00 ± 0.03). The differences were also statistically significant (F = 280.06, P < 0.001).

CONCLUSIONCadmium chloride could significantly enhance the phosphorylation of MAPK in NRK cells; and it is probably associated with the activation of MAPK.

Animals ; Cadmium Chloride ; toxicity ; Cell Line ; Epithelial Cells ; drug effects ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Phosphorylation ; Rats ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo study the effects of benzo(a)pyrene (BaP) on the cell cycle distribution and activities of mitogen-activated protein kinase (MAPK) signal molecules (ERK1/2, JNK1/2 and p38) in human embryo lung cells (HELF), and to investigate the relationship between alterations of MAPK protein phosphorylation and the cell cycle distributions.

METHODSThe phosphorylation of MAPK were induced by exposing HELF cells to BaP at 0.1, 0.5, 2.5 and 12.5 micromol/L. The phosphorylation and protein expression levels of ERK1/2, JNK1/2 and p38 were determined through western-blotting assay. And the flow cytometry assay was used to measure the cell cycle effects in HELF cells after treatment with 2.5 micromol/L BaP for 24 h.

RESULTSThe phosphorylation levels of ERK1/2, JNK1/2 and p38 were significantly increased through BaP exposure. In addition, the phosphorylation of these three MAPKs has similar alteration pattern. We found that exposure of cells to 2.5 microM of BaP for 24 h resulted in a decrease of G(0) and G(1) population by 11.9% (F = 41.38, P < 0.01) and an increase of S population by 17.2% (F = 68.13, P < 0.01). Three chemical inhibitors of MAPK (AG126, SP600125 and SB203580) could significantly inhibit the cell cycle alteration because of BaP treatment.

CONCLUSIONERK1/2, JNK1/2 and p38 could positively regulate the BaP independently induced cell cycle alterations.

Benzo(a)pyrene ; toxicity ; Cell Cycle ; drug effects ; Cells, Cultured ; Fibroblasts ; drug effects ; metabolism ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Lung ; cytology ; embryology ; MAP Kinase Kinase 4 ; metabolism ; MAP Kinase Signaling System ; drug effects ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Mitogen-Activated Protein Kinase 8 ; metabolism ; Mitogen-Activated Protein Kinase 9 ; metabolism ; Signal Transduction ; drug effects ; p38 Mitogen-Activated Protein Kinases ; metabolism

The aim of this study was to investigate the apoptosis-inducing effect of gambogic acid (GA) on Jurkat cells and its underlying signaling pathway. Apoptosis induced by GA and some inhibitors was assayed by Annexin V/PI doubling staining. The levels of caspase 3, caspase 8 and caspase 9 activated in living Jurkat cells were measured by flow cytometry. The expressions of caspase 3, caspase 9, p-JNK and P38 were detected by Western blot. The results showed that GA induced apoptosis of Jurkat cells in a dose-dependent manner. The positive cell number of activated caspase 3, caspase 8, caspase 9 and the levels of activated caspase 3, caspase 9, p-JNK, P38 increased after Jurkat cells were treated with GA. ROS, CaMKII, caspase 3, caspase 9, MAPKK, JNK1/2 and P38 inhibitors had some significant effect on GA-induced apoptosis. ROS, CaMKII, MAPKK, JNK1/2 and P38 inhibitors decreased the levels of activated caspase 3, caspase 9 by GA.ROS, CaMKII, MAPKK, JNK1/2 inhibitors decreased the levels of p-JNK by GA. ROS, CaMKII, MAPKK, P38 inhibitors decreased the levels of P38 by GA. It is concluded that GA induced apoptosis of Jurkat cells by activated caspases through activating of ROS-CaMKII-MAPKK-JNK/P38 pathway.
Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Caspase 9 ; metabolism ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Jurkat Cells ; MAP Kinase Signaling System ; drug effects ; Xanthones ; pharmacology ; p38 Mitogen-Activated Protein Kinases ; metabolism

Unmethylated CpG oligodeoxynucleotides (CpG ODNs) activate immune cells to produce immune mediators. This study demonstrates that in murine macrophage RAW 264.7 cells, CpG ODN-mediated matrix metalloproteinase-9 (MMP-9) expression is regulated at transcriptional level and requires de novo protein synthesis. Inhibition of ERK and p38 MAPK, but not JNK, results in significant decrease of CpG ODN-induced MMP-9 expression. We found that endosomal maturation inhibitors, chloroquine and bafilomycin A, block CpG ODN-induced ERK and p38 MAPK activation and the subsequent MMP-9 expression. We also observed that CpG ODN induces NF-kappa B activation and NF-kappa B is a downstream target of p38 MAPK. Taken together, our data demonstrate that CpG ODN triggers MMP-9 expression via TLR-9 dependent ERK and p38 MAPK activation followed by NF-kappa B activation.
Animals ; Cell Line ; Enzyme Activation/drug effects ; Enzyme Induction/drug effects ; Matrix Metalloproteinase 9/*biosynthesis ; Mice ; Mitogen-Activated Protein Kinase 1/antagonists & inhibitors/metabolism ; Mitogen-Activated Protein Kinase 3/antagonists & inhibitors/metabolism ; Mitogen-Activated Protein Kinases/*metabolism ; NF-kappa B/*metabolism ; Oligodeoxyribonucleotides/*pharmacology ; Signal Transduction/drug effects ; Toll-Like Receptor 9/antagonists & inhibitors/*metabolism ; p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors/metabolism

OBJECTIVEThe objective of this paper was to study the change of P38MAPK and Fas in the apoptosis of THP-1 cells induced by allicin.

METHODThe proliferation inhibition rates of THP-1 cells after various treatments were examined by MTT assay. Apoptosis rate was determined with Annexin V- FITC/PI double staining by flow cytometry. The expression and distribution change of the phosphorylation p38MAPK (P-p38MAPK) were detected by immunohistochemical staining. The changes of P-p38 MAPK and Fas proteins were detected by Western blot.

RESULTThe proliferations of leukemia cell line THP-1 are inhibited by allicin. MTT assay showed that allicin can inhibit the proliferation of the THP-1 cell, and the inhibition was dependent on both dose and time. The IC50 of 72 hours was 12.8 mg x L(-1). Apoptosis rate detected by Annexin V-FITC/PI was proportional to the concentration of the allicin. After the immunohistochemical staining test, the P-p38MAPK was located in the cell nucleus and plasma, showing deep brown, when adding allicin to THP-1 cell. Western blot test showed that the P-p38MAPK proteins expression was proportional to the concentration of Allicin and was also dose dependent. The levels of P-p38MAPK in negative control group, 1/2 IC50 of 72 hours group and IC50 of 72 hours group were 0.259 8 +/- 0.013 2, 0.61 2 +/- 0.008 3 and 0.505 6 +/- 0.005 5 respectively, and the levels of Fas proteins were 0.287 4 +/- 0.008 9, 0.426 8 +/- 0.007 9 and 0.597 1 +/- 0.010 9 respectively. The difference was statistically significant when compared with the negative control group (P < 0.01).

CONCLUSIONAllicin can significantly induce THP-1 cells apoptosis, and its mechanism may be related to the activation of P38MAPK/Fas.

Apoptosis ; drug effects ; Cell Line, Tumor ; Humans ; Neoplasms ; drug therapy ; metabolism ; physiopathology ; Phosphorylation ; Signal Transduction ; drug effects ; Sulfinic Acids ; pharmacology ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism

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

OBJECTIVETo investigate the expressions of P38 mitogen-activated protein kinases (P38 MAPK), JNK mitogen-activated protein kinases (JNK MAPK) and the therapeutical effects of melatonin in the renal tissue of acute acuteparaquat-induced rats.

METHODSSeventy-eight healthy adult Sprague-Dawley (SD) rats (39 male, 39 female) were randomly divided into three groups: (1) Control group (group A): 6 rats, (2) Poisoned group (group B): 36 rats, (3) Therapeutical group (group C): 36 rats. At 1, 3, 5, 7, 10 and 14 days after poisoning, six rats in Group B and group C were used to assess renal pathological changes and the expression of P38 MAPK, JNK MAPK in kidney were evaluated by immunohistochemistry.

RESULTSCompared with control group, the expression of P38MAPK in renal tissue of poisoned group significantly rose at the first day, reached the peak at the 10th day and afterwards decreased slowly. Expression of JNK MAPK reached the peak at the first day, and kept at relatively high levels up to the 14th day. Melatonin weakened markedly the expressions of P38 MAPK and JNK MAPK in renal tissue of acute acuteparaquat-induced rats.

CONCLUSIONP38 MAPK and JNK MAPK play an important role in renal injury of acute paraquat -poisoning rats. Melatonin takes a significant effect on the activation of them.

Animals ; Female ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Kidney ; drug effects ; metabolism ; physiopathology ; Male ; Melatonin ; therapeutic use ; Paraquat ; poisoning ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases ; metabolism

Sauchinone has been known to have anti-inflammatory and antioxidant effects. We determined whether sauchinone is beneficial in regional myocardial ischemia/reperfusion (I/R) injury. Rats were subjected to 20 min occlusion of the left anterior descending coronary artery, followed by 2 hr reperfusion. Sauchinone (10 mg/kg) was administered intraperitoneally 30 min before the onset of ischemia. The infarct size was measured 2 hr after resuming the perfusion. The expression of cell death kinases (p38 and JNK) and reperfusion injury salvage kinases (phosphatidylinositol-3-OH kinases-Akt, extra-cellular signal-regulated kinases [ERK1/2])/glycogen synthase kinase (GSK)-3beta was determined 5 min after resuming the perfusion. Sauchinone significantly reduced the infarct size (29.0% +/- 5.3% in the sauchinone group vs 44.4% +/- 6.1% in the control, P < 0.05). Accordingly, the phosphorylation of JNK and p38 was significantly attenuated, while that of ERK1/2, Akt and GSK-3beta was not affected. It is suggested that sauchinone protects against regional myocardial I/R injury through inhibition of phosphorylation of p38 and JNK death signaling pathways.
Animals ; Benzopyrans/*pharmacology ; Dioxoles/*pharmacology ; Glycogen Synthase Kinase 3/metabolism ; JNK Mitogen-Activated Protein Kinases/*metabolism ; Mitogen-Activated Protein Kinase 1/metabolism ; Mitogen-Activated Protein Kinase 3/metabolism ; Myocardial Reperfusion Injury/*metabolism/pathology/prevention & control ; Phosphorylation ; Protective Agents/*pharmacology ; Rats ; Signal Transduction/*drug effects ; p38 Mitogen-Activated Protein Kinases/*metabolism

OBJECTIVETo explore the role of the P38 signaling pathway in the apoptosis of arsenic trioxide (As2 O3)-induced androgen-independent prostate cancer PC-3 cells.

METHODSAndrogen-independent prostate cancer PC-3 cells were treated with different concentrations of As2 O3 for 24, 48 and 72 hours. The inhibitory effect of As2 O3 on the cell growth was measured by MTT, the expression of p- P38 detected by Western blot, and the rate of cell apoptosis determined by Annexin V and PI double staining before and after interfering the P38 signaling pathway by SB203580, a highly selective P38 inhibitor.

RESULTSAs2 O3 inhibited the proliferation of PC-3 cells in a concentration- and time-dependent manner, and quickly activated P38 phosphorylation, thus giving full play to its biological activities. After 24 hours of treatment with As2 O3 at the concentrations of 2, 10 and 20 micromol/L, the apoptosis rates of the PC-3 cells were (18.9 +/- 0.43), (24.7 +/- 0.29) and (49.7 +/- 1.79)%, respectively, which were reduced to (14.8 +/- 0.81), (22.1 +/- 0.51) and (39.6 +/- 1.74)% after interfering the P38 pathway with SB203580. Inhibition of the P38 pathway significantly reduced the apoptosis of the PC-3 cells induced by As2 O3 (P < 0.05).

CONCLUSIONAs2 O3 can induce the apoptosis of prostate cancer PC-3 cells by activating the P38 signaling pathway, and interfering the P38 signaling pathway can reduce their apoptosis, which suggests that the P38 signaling pathway is involved in the apoptosis of As2 O3-induced androgen-independent prostate cancer PC-3 cells.

Arsenicals ; pharmacology ; Cell Line, Tumor ; Humans ; MAP Kinase Signaling System ; drug effects ; Male ; Oxides ; pharmacology ; Prostatic Neoplasms ; pathology ; Signal Transduction ; drug effects ; p38 Mitogen-Activated Protein Kinases ; metabolism