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 investigate the intracellular distribution and the activation of mitogen-activated protein kinases (MAPKs) in myocardial cells in scalded rats.

METHODSWistar rats were used in this study and forty of them were inflicted with 40% III degree scald on the back and eight normal ones as control. The samples of plasma and myocardial tissue were harvested at 1, 3, 6, 12 and 24 postburn hours (PBHs), and samples were also obtained from normal rats as control. The plasma CK-MB activity was determined by routine method. The activation states of all the members of MAPKs [p38 kinase, ERKs (extracellular signal-regulated protein kinases) and JNK (c-Jun N-terminal kinase)] in the myocardial tissue samples were detected by Western blotting. The tissue slides were stained by immunohistochemistry methods.

RESULTSActivation of p38 kinase and ERK with nuclear translocation was found postburn, especially during 1, 3 and 6 PBHs (P < 0.01). But there was no activation of JNK during 1 - 24 PBHs. The plasma CK-MB content increased at 3 PBH and reached summit at 12 PBHs (P < 0.05 - 0.01).

CONCLUSIONp38 kinase and ERK signal pathways might play important roles in the early postburn injury of myocardial cells, inducing myocardial injury.

Animals ; Burns ; metabolism ; Female ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Male ; Mitogen-Activated Protein Kinases ; metabolism ; Myocytes, Cardiac ; metabolism ; pathology ; Rats ; Rats, Wistar ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases ; metabolism

To study the effect of cholecystokinin-octapeptide (CCK-8) on systemic hypotension and cytokine production in serum and lung of endotoxic shock (ES) rats induced by lipopolysaccharide (LPS) and investigate its signal transduction mechanism of p38 mitogen-activated protein kinase (MAPK), the changes in mean arterial pressure (MAP) were observed by using a polygraph in four groups of SD rats: group of LPS (8 mg/kg i.v.) induced ES, group of CCK-8 (40 microg/kg i.v.) pretreatment 10 min before LPS (8 mg/kg) administration, group of CCK-8 (40 microg/kg i.v.) only, and normal saline (control) group; the contents of proinflammatory cytokines (TNF-alpha, IL-1 beta and IL-6) in the lung and serum were assayed using ELISA kits; and p38 MAPK was detected by Western blot. The results showed that CCK-8 alleviated LPS-induced decrease in MAP of rats; compared with the control, LPS elevated the levels of TNF-alpha, IL-1 beta and IL-6 in serum and lung significantly, while CCK-8 significantly inhibited the LPS-induced increases in TNF-alpha, IL-1 beta and IL-6 in serum and lung. The activation of p38 MAPK in the lung of ES rats was enhanced by CCK-8 pretreatment. These results suggest that CCK-8 can alleviate the LPS-induced decrease in MAP of ES rats and exert an inhibitory effect on the overproduction of proinflammatory cytokines, and that p38 MAPK may be involved in its signal transduction mechanisms.
Animals ; Cytokines ; biosynthesis ; Lung ; metabolism ; Male ; Mitogen-Activated Protein Kinases ; biosynthesis ; physiology ; Rats ; Rats, Sprague-Dawley ; Shock, Septic ; drug therapy ; metabolism ; Sincalide ; pharmacology ; p38 Mitogen-Activated Protein Kinases

: To assess the () recombinant gingivalis gingipain R2 (rRgpB)-induced Ca mobilization in human gingival fibroblast (HGF) mediated by protease-activated receptor (PAR) and its downstream signal transduction pathways. : Flow cytometry was used to detect the expression of PAR in HGF. The proliferation of HGF was measured by CCK-8. The dynamic changes of intracellular Ca concentration in HGF induced by rRgpB and the blocking effect of PAR-1 antagonist were observed by laser confocal microscopy. Western blot was performed to determine the phosphorylation levels of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) 1/2, p38 mitogen-activated protein kinase (p38 MAPK) and p65 in HGF. : PAR-1 and PAR-3 were expressed in HGF, and the rRgpB could promote the proliferation of HGF. rRgpB caused a transient increase in [Ca], which could be completely suppressed by vorapaxar, a PAR-1 antagonist. The phosphorylation levels of JNK, ERK1/2 and p65 were significantly up-regulated after the induction of rRgpB for and (all <0.05), which was completely inhibited by vorapaxar. However, the phosphorylation level of p38 MAPK had no significant change after rRgpB stimulation. : rRgpB causes an increase in [Ca] in HGF mediated by PAR-1. JNK, ERK1/2 and nuclear factor-κB may be involved in intracellular signal transduction after PAR-1 activation.
Fibroblasts ; Humans ; JNK Mitogen-Activated Protein Kinases/metabolism* ; MAP Kinase Signaling System ; Phosphorylation ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases/metabolism*

The MAPK signaling pathway plays a key role in the differentiation, proliferation and apoptosis of cells, and its family members mainly include extracellular signal-regulated kinase (ERK), stress-activated protein kinase (JNK), and p38 mitogen-activated protein kinase (p38MAPK). Recent studies have shown that the ERK, JNK and p38MAPK signaling pathways are closely associated with the development and progression of erectile dysfunction (ED). This review focuses on the correlation between the MAPK signaling pathway and ED.
Apoptosis ; Cell Differentiation ; Cell Proliferation ; Erectile Dysfunction ; etiology ; metabolism ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; MAP Kinase Signaling System ; Male ; Mitogen-Activated Protein Kinases ; metabolism ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases ; metabolism

Cells, Cultured ; Chemokine CCL2 ; biosynthesis ; genetics ; Endothelial Cells ; metabolism ; Humans ; Mitogen-Activated Protein Kinases ; biosynthesis ; genetics ; RNA, Messenger ; genetics ; Umbilical Veins ; cytology ; p38 Mitogen-Activated Protein Kinases

OBJECTIVETo study the effects of sodium butyrate (NaBu) on cell cycle checkpoint and the apoptosis sensitivity in U937 cells.

METHODSTwo mutant U937 cell lines, U937-ASPI3K (ATM negative) and U937-pZeosv2(+) (ATM wild-type), were used as the cell model system. Immunoprecipitation and kinase assay were used to examine the p38 MAPK and ERK1 kinase activities. Western blot was used to analyze the phosphorylation of Bad protein.

RESULTSU937-pZeosv2(+) pretreated with NaBu exhibited enhanced apoptotic response in a NaBu dose dependent fashion upon (137)Cs irradiation, which could be abolished by olomoucine (OLM), a p38 MAPK specific inhibitor. On the other hand, Cyclin dependent kinase 2 (CDK2) specific inhibitor CDK2-I and p34cdc2/cyclinB inhibitor alsterpaullone (ALP) failed to block the effects of NaBu. Similar results were also observed in U937-ASPI3K. The effect of irradiation on p38 MAPK and ERK1 was strikingly potentiated by NaBu. Furthermore, inactivation of irradiated Bad protein via phosphorylation on serine 136 was also enhanced.

CONCLUSIONNaBu is able to enhance the apoptotic response in U937 cells, which is mediated by p38 MAPK activation but not ATM status.

Apoptosis ; Butyrates ; pharmacology ; Carrier Proteins ; metabolism ; Humans ; MAP Kinase Signaling System ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; U937 Cells ; bcl-Associated Death Protein ; p38 Mitogen-Activated Protein Kinases

Animals ; Liver ; metabolism ; Liver Regeneration ; Male ; Rats ; Rats, Wistar ; Smad Proteins ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo investigate the signaling pathway through testing the effects of dexamethasone (Dex) on the activation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 kinase (p38) in HO-8910 cells.

METHODSActivation of the ERK1/2 and p38 was detected by Western blotting using the antibodies against the total ERK1/2 and p38 mitogen-activated protein kinases (MAPKs) protein and the phosphorylated forms of them.

RESULTSDex could suppress the activation of ERK1/2, while enhance the activation of p38 rapidly and strongly in a dose- and time- dependent manner. Neither effect could be blocked by RU486, the antagonist of glucocorticoid receptor (GR).

CONCLUSIONDex has rapid effects on the activation of ERK1/2 and p38, and these effects are not mediated by GR.

Cell Division ; physiology ; Dexamethasone ; pharmacology ; Enzyme Activation ; Female ; Glucocorticoids ; pharmacology ; Humans ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases ; metabolism ; Ovarian Neoplasms ; enzymology ; pathology ; Signal Transduction ; Tumor Cells, Cultured ; p38 Mitogen-Activated Protein Kinases