OBJECTIVE: To investigate the effects of myeloid differentiation-2 (MD2) gene silencing on high glucose-induced proliferation inhibition, apoptosis and inflammation in rat cardiomyocytes. METHODS: The immortalized rat cardiomyocyte cell line H9C2 were transfected with MD2 small interfering RNA (si-MD2) and negative control for 24 h, then stimulated with high glucose (HG) for 48 h. RT-qPCR was performed to detect the mRNA levels of MD2 and inflammatory factors TNF-α, IL-1β and IL-6. MTS and flow cytometry were used to evaluate cell proliferation, cell cycle and apoptosis rate. Western blot was used to detect protein expression levels and phosphorylation levels. RESULTS: The mRNA and protein levels of MD2 in H9C2 cells were dramatically decreased after transfected with si-MD2 (P＜0.01). After stimulation of high glucose, the mRNA levels of inflammatory factors, the cells in G0/G1 phase , the cell apoptosis rate and the protein level of cleaved Caspase-3 were significantly increased, while the cell proliferation ability was decreased (P＜0.01). MD2 gene silencing antagonized the effects of high glucose on cell proliferation, cell cycle, cell apoptosis and the mRNA levels of TNF-α, IL-1β , IL-6(P＜0.05). Western blot analysis showed that the phosphorylation levels of extracellular signal-regulated kinase(ERK1/2), P38 mitogen-activated protein kinase(P38 MAPK) and C-Jun N-terminal kinase(JNK) protein were increased significantly in H9C2 cells treated with high glucose, which could be reversed by silencing of MD2 (P＜0.01). CONCLUSION This study demonstrates that MD2 gene silencing reverses high glucose-induced myocardial inflammation, apoptosis and proliferation inhibition via the mechanisms involving suppression of ERK, P38 MAPK, JNK signaling pathway.
Animals ; Apoptosis ; Cell Proliferation ; Cells, Cultured ; Cytokines ; metabolism ; Gene Silencing ; Glucose ; Inflammation ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Lymphocyte Antigen 96 ; genetics ; Myocytes, Cardiac ; cytology ; Rats ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo investigate the effect of interleukin-6 (IL-6) on the human growth hormone (hGH) gene expression in a rat somatotropic pituitary cell line MtT/S.

METHODSThe plasmids containing various lengths of hGH gene 5'-promoter fragments were constructed. Stably transfected MtT/S cells were created by cotransfecting the above plasmids and pcDNA3. 1(+) with DMRIE-C transfection reagent After the administration of these cells with IL-6 and/or various inhibitors of signaling transduction pathways, the luciferase activities in MtT/S cells lysis were assayed to demonstrate the effects of IL-6 on hGH gene promoter activity and possibly involved mechanism.

RESULTSThe 10(3) U/mL IL-6 stimulated GH secretion and synthesis, and promoted the 5'-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.69 times above the control. Among inhibitors of signaling transduction pathways, mitogen-activated protein kinase kinase (MAPKK/MEK) inhibitor PD98059 (40 micromol/L) and p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 (5 micromol/L) completely blocked the stimulatory effect of IL-6. Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells. Neither over-expression of Pit-1 nor inhibition of Pit-1 expression affected IL-6 induction of hGH promoter activity. A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-6. The results showed that the stimulatory effect of IL-6 was abolished following deletion of the -196 to - 132 bp fragment.

CONCLUSIONSIL-6 promotes GH secretion and synthesis by rat MtT/S somatotroph cells. The stimulatory effect of IL-6 on hGH gene promoter appears to require the activation of MEK and p38 MAPK, and a fragment of promoter sequence that spans the - 196 to - 132 bp of the gene, but may be unlinked with Pit-1 protein.

Animals ; Cell Line ; Gene Expression Regulation ; Human Growth Hormone ; genetics ; metabolism ; Humans ; Interleukin-6 ; genetics ; metabolism ; JNK Mitogen-Activated Protein Kinases ; genetics ; metabolism ; MAP Kinase Signaling System ; physiology ; Mitogen-Activated Protein Kinase Kinases ; genetics ; metabolism ; Promoter Regions, Genetic ; Rats ; Somatotrophs ; cytology ; metabolism ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism

OBJECTIVETo explore the functional effects of MAPK pathway in the pathogenesis of human osteosarcoma.

METHODSGene microarray (Human Genome U133A, Affymetrix) was used to screen the differential expression of genes involved in MAPK pathway between osteosarcoma cell lines and 3 osteoblastic cell lines. KEGG metabolic pathway analysis was performed among significantly increased or decreased genes using the MATLAB software. Immunohistochemical technique was used to detect the expressions of ERK1/2, JNK and p38 proteins among 48 osteosarcoma and benign 24 osteoblastic tumor samples.

RESULTSUsing an entrance limit of > or = 2.0, 18 differentially expressed MAPK pathway-related genes were selected (10 up-regulated, 8 down-regulated) to mapped to the MAPK pathway of KEGG which are all important node genes. The positive rates of ERK1/2, JNK and p38 proteins were 83.3% (40/48), 72.9% (35/48) and 85.4% (41/48) in osteosarcomas,and 12.5% (3/24), 8.3% (2/24) and 16.7% (4/24) in the control group, respectively. The positive rates and expression intensities were statistically different between the 2 groups (P<0.01).

CONCLUSIONMAPK pathway plays an important role in the pathogenesis of osteosarcoma. ERK, JNK and p38 form an intercoordinating network and regulate the cell proliferation, differentiation, apoptosis, invasion and migration in osteosarcoma.

Adolescent ; Adult ; Aged ; Bone Neoplasms ; genetics ; metabolism ; pathology ; Cell Line, Tumor ; Child ; Female ; Gene Expression Profiling ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Male ; Middle Aged ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Oligonucleotide Array Sequence Analysis ; Osteoblastoma ; genetics ; metabolism ; pathology ; Osteosarcoma ; genetics ; metabolism ; pathology ; Signal Transduction ; Young Adult ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo investigate the effect of adenosine A2A receptor knockout (A(2A)RKO) on relationship between continuous activation of phospho-c-Jun N-terminal kinase (P-JNK) and expression of nerve cell apoptosis in hippocampus CA1 domain of newborn mice after hypoxia/ischemia brain damage(HIBD) and its potential mechanism.

METHODSA(2A)RKO mice and adenosine A2A receptor wildtype (A(2A)RWT) littermates (n = 80) were divided into Sham operation group (S) and model group (M), 1, 3 and 7 day after HIBD, totally 8 groups. HIBD was developed with 7 day-old neonatal mice according classical Rice-Vannucci method. It was tested the effect of A(2A)RKO on short-term neurofunctional outcomes consisted of three developmental reflexes (righting, geotaxis and cliff aversion), the changes of brain pathology with hematoxylin-eosin (HE) staining and Nissl staining, the expressions of nerve cell apoptosis with terminal deoxynucleotidyl transferase mediated dUTP-biotin nick-end labeling(TUNEL) staining and P-JNK were observed by immunohistochemistry.

RESULTSThe neurological behavior injuries and brain histopathological damages and nerve apoptosis cells were aggravated in A(2A)RKO newborn mice after HIBD. The positive expressions of P-JNK were significantly higher in the ischemic hippocampus CA1 domain after HIBD than ones in group S respectively (P < 0.01), reaching to peak at 1 day and then began gradually decreasing. P-JNK expression in model knockout(MKO) at 1, 3 and 7 day increased greatly compared to those in the previous time point of corresponding model wildtype (MWT) (P < 0.01, P < 0.05, P > 0.05); there was a positive correlation between the expressions of P-JNK and nerve cell apoptosis after HIBD in newborn mice(r = 0.837, P < 0.01).

CONCLUSIONEarly continuous activation of P-JNK might be involved in the aggravated nerve apoptosis cells and brain damage induced by A(2A) RKO newborn mice after HIBD.

Animals ; Animals, Newborn ; Apoptosis ; Hypoxia-Ischemia, Brain ; metabolism ; pathology ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Mice ; Mice, Knockout ; Neurons ; drug effects ; metabolism ; pathology ; Receptor, Adenosine A2A ; genetics

OBJECTIVETo explore the effects of antisense epidermal growth factor receptor (EGF-R) oligodeoxynucleotides on ultraviolet-induced c-jun activity of keratinocytes after EGF-R oligodeoxynucleotides transfect to HaCaT in vitro.

METHODSc-jun DNA binding activity after ultraviolet-B (UVB) irradiation and EGF-R oligodeoxynucleotides transfection were determined with a highly sensitive and specific colorimetric method. After EGF-R oligodeoxynucleotides transfection, the mRNA level of EGF-R was detected by reverse transcription polymerase chain reaction method.

RESULTSCompared with control groups, c-jun activity increased significantly in UVB (10, 20, 30 mJ/cm2) irradiation groups (P < 0.05). EGF-R mRNA and c-jun activities induced by UVB were inhibited after the keratinocytes were transfected with EGF-R antisense oligodeoxynucleotides at 2, 4 and 8 microg/ml concentrations (P < 0.01).

CONCLUSIONThe ultraviolet-induced c-jun activity of keratinocytes can be mediated by EGF-R and inhibited by EGF-R antisense oligodeoxynucleotides, which is transfected to keratinocytes and mediated by lipofectamine.

Cell Line ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Keratinocytes ; drug effects ; metabolism ; radiation effects ; Oligodeoxyribonucleotides, Antisense ; pharmacology ; Receptor, Epidermal Growth Factor ; biosynthesis ; genetics ; Transfection ; Ultraviolet Rays

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

BACKGROUNDNajanalgesin, a toxin isolated from the venom of Naja naja atra, has been shown to exert significant analgesic effects in a neuropathic pain model in rats. However, the molecular mechanism underlying this protective effect of najanalgesin is poorly understood. The present study sought to evaluate the intracellular signaling pathways that are involved in the antinociceptive effect of najanalgesin on neuropathic pain.

METHODSThe antinociceptive properties of najanalgesin were tested in hind paw withdrawal thresholds in response to mechanical stimulation. We analyzed the participation of the mitogen-activated protein kinase p38, extracellular-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) by western blot analysis. This inhibition of JNK was confirmed by immunohistochemistry.

RESULTSThe phosphorylation levels of JNK (as well as its downstream molecule c-Jun), p38, and ERK were significantly increased after injury. Najanalgesin only inhibited JNK and c-Jun phosphorylation but had no effect on either ERK or p38. This inhibition of JNK was confirmed by immunohistochemistry, which suggested that the antinociceptive effect of najanalgesin on spinal nerve ligation-induced neuropathic pain in rats is associated with JNK activation in the spinal cord.

CONCLUSIONThe antinociceptive effect of najanalgesin functions by inhibiting the JNK in a neuropathic pain model.

Animals ; Elapid Venoms ; therapeutic use ; Extracellular Signal-Regulated MAP Kinases ; genetics ; metabolism ; Immunohistochemistry ; JNK Mitogen-Activated Protein Kinases ; genetics ; metabolism ; Male ; Neuralgia ; drug therapy ; enzymology ; Proto-Oncogene Proteins c-jun ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism

Following acute and chronic liver injury, hepatic stellate cells (HSCs) become activated to undergo a phenotypic transformation into myofibroblast-like cells and lose their retinol content, but the mechanisms of retinoid loss and its potential roles in HSCs activation and liver fibrosis are not understood. The influence of retinoids on HSCs and hepatic fibrosis remains controversial. The purpose of this study was to evaluate the effects of all-trans retinoid acid (ATRA) on cell proliferation, mRNA expression of collagen genes [procollagen α1 (I), procollagen α1 (III)], profibrogenic genes (TGF-β(1), CTGF, MMP-2, TIMP-1, TIMP-2, PAI-1), fibrolytic genes (MMP-3, MMP-13) and the upstream element (JNK and AP-1) in the rat hepatic stellate cell line (CFSC-2G). Cell proliferation was evaluated by measuring BrdU incorporation. The mRNA expression levels of collagen genes [procollagen α1 (I), procollagen α1 (III)], profibrogenic genes (TGF-β(1), CTGF, MMP-2, TIMP-1, TIMP-2, PAI-1), and fibrolytic genes (MMP-3, MMP-13) were quantitatively detected by using real-time PCR. The mRNA expression of JNK and AP-1 was quantified by RT-PCR. The results showed that ATRA inhibited HSCs proliferation and diminished the mRNA expression of collagen genes [procollagen α1 (I), procollagen α1 (III)] and profibrogenic genes (TGF-β(1), CTGF, MMP-2, TIMP-1, TIMP-2, PAI-1), and significantly stimulated the mRNA expression of MMP-3 and MMP-13 in HSCs by suppressing the mRNA expression of JNK and AP-1. These findings suggested that ATRA could inhibit proliferation and collagen production of HSCs via the suppression of active protein-1 and c-Jun N-terminal kinase signal, then decrease the mRNAs expression of profibrogenic genes (TGF-β(1), CTGF, MMP-2, TIMP-1, TIMP-2, PAI-1), and significantly induce the mRNA expression of MMP-3 and MMP-13.
Animals ; Cell Line ; Cell Proliferation ; drug effects ; Collagen ; metabolism ; Collagen Type I ; genetics ; metabolism ; Hepatic Stellate Cells ; cytology ; metabolism ; JNK Mitogen-Activated Protein Kinases ; genetics ; metabolism ; Rats ; Transcription Factor AP-1 ; genetics ; metabolism ; Tretinoin ; pharmacology

OBJECTIVETo study the effect of transforming growth factor-β activated kinase-1 (TAK1) gene silencing on the proliferation and apoptosis of Kasumi-1 cells induced by arsenic trioxide (As₂O₃).

METHODSAcute myeloid leukemia with t(8;21) cell line Kasumi-1 cells were treated with As₂O₃ or in combination with TAK1 siRNA interference technology. The experiment was divided into four groups: Kasumi-1 cells without any treatment, TAK1 specific siRNA transfection alone, Kasumi-1 cells treated with different concentration of As₂O₃, TAK1siRNA transfection combined with As₂O₃. CCK-8 was used to detect the cell viability. The expression of phosphorylated c-Jun N-terminal kinase (P-JNK) was determined by Western Blot. Cell apoptosis and growth were examined by morphological and colony formation assay.

RESULTSAfter Kasumi-1 cells were treated with As₂O₃, the rate of cell inhibition was concentration-dependent, and the 50% inhibitory concentration was 3.5 μmol/L. The highest expression level of P-JNK appeared in 30 minutes after cells were treated with As₂O₃. The apoptosis rates of Kasumi-1 cells without any treatment, TAK1 siRNA interference alone group, As₂O₃ alone group and the combined group were (5.02 ± 1.13)%, (6.18 ± 0.28)%, (48.33 ± 2.70)% and (86.07 ± 2.21)%; colony formation rates were (73.83 ± 2.78)%, (76.03 ± 1.46)%, (55.07 ± 1.50)% and (22.20 ± 1.15)%; apoptosis rate of TAK1 siRNA group and the untreated group has no significant difference (P = 0.052); colony formation rate between TAk1 siRNA group and the untreated group has no significant difference (P = 0.179), but the difference in other groups was significant (P = 0.000).

CONCLUSIONSilencing the expression of TAK1 can enhance the anti-proliferative and pro-apoptotic effect of As₂O₃ on Kasumi-1 cells, and its mechanism may be through the TAK1 downstream JNK signal pathway.

Apoptosis ; drug effects ; Arsenicals ; pharmacology ; Cell Line, Tumor ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Leukemia, Myeloid, Acute ; enzymology ; pathology ; MAP Kinase Kinase Kinases ; genetics ; metabolism ; Oxides ; pharmacology ; RNA Interference ; RNA, Small Interfering ; genetics ; Signal Transduction

The early growth response-1 gene (egr-1) encodes a zinc-finger transcription factor Egr-1 and is rapidly inducible by a variety of extracellular stimuli. Anisomycin (ANX), a protein synthesis inhibitor, stimulates mitogen-activated protein kinase (MAPK) pathways and thereby causes a rapid induction of immediate-early response genes. We found that anisomycin treatment of U87MG glioma cells resulted in a marked, time-dependent increase in levels of Egr-1 protein. The results of Northern blot analysis and reporter gene assay of egr-1 gene promoter (Pegr-1) activity indicate that the ANX- induced increase in Egr-1 occurs at the transcriptional level. Deletion of the serum response element (SRE) in the 5'-flanking region of egr-1 gene abolished ANX-induced Pegr-1 activity. ANX induced the phosphorylation of the ERK1/2, JNK, and p38 MAPKs in a time-dependent manner and also induced transactivation of Gal4-Elk-1, suggesting that Elk-1 is involved in SRE-mediated egr-1 transcription. Transient transfection of dominant-negative constructs of MAPK pathways blocked ANX-induced Pegr-1 activity. Furthermore, pretreatment with specific MAPK pathway inhibitors, including the MEK inhibitor U0126, the JNK inhibitor SP600125, and the p38 kinase inhibitor SB202190, completely inhibited ANX-inducible expression of Egr-1. Taken together, these results suggest that all three MAPK pathways play a crucial role in ANX-induced transcriptional activation of Pegr-1 through SRE-mediated transactivation of Elk
p38 Mitogen-Activated Protein Kinases/genetics/metabolism ; ets-Domain Protein Elk-1/genetics/*metabolism ; Trans-Activation (Genetics)/*drug effects ; Serum Response Element ; Protein Kinase Inhibitors/pharmacology ; Protein Biosynthesis/*drug effects ; Promoter Regions (Genetics)/genetics ; *MAP Kinase Signaling System/drug effects ; JNK Mitogen-Activated Protein Kinases/genetics/metabolism ; Humans ; Extracellular Signal-Regulated MAP Kinases/genetics/metabolism ; Early Growth Response Protein 1/genetics/*metabolism ; Cell Line, Tumor ; Anisomycin/*pharmacology