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 investigate the MEK and ERK expression and their relationship with clinicopathological parameters in human breast carcinoma, and the effect of preoperative chemotherapy on MEK and ERK protein expression.

METHODSSamples were obtained from 56 patients with breast carcinoma and 8 patients with benign tumors. Sixteen of the 56 patients received preoperative chemotherapy. Western blot and immunohistochemistry were used to measure the expression of MEK1, MEK2 and ERK1, ERK2 protein.

RESULTSMEK2 and ERK1, ERK2 protein levels were increased in breast carcinoma tissue compared with those in adjacent normal tissues (t = 7.244, 5.959, 3.735, P < 0.01) and benign tumors (t = 2.206, P < 0.05). The levels of MEK1 were decreased. The expression of MEK2 protein in ER negative patients was higher than that in ER positive ones. MEK2 protein levels were lower in patients who received preoperative chemotherapy than in those who did not.

CONCLUSIONOverexpression of MEK-ERK may play an important role in the development of human breast carcinoma. MEK and ERK protein expressions are inhibited by preoperative chemotherapy.

Adult ; Aged ; Blotting, Western ; Breast Neoplasms ; diagnosis ; enzymology ; metabolism ; Female ; Humans ; Immunohistochemistry ; MAP Kinase Kinase 1 ; MAP Kinase Kinase 2 ; MAP Kinase Signaling System ; physiology ; Middle Aged ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Prognosis ; Protein Kinases ; metabolism ; Protein-Serine-Threonine Kinases ; metabolism ; Protein-Tyrosine Kinases ; metabolism

AIMTo assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun N-terminal kinases (JNK) and p38 mitogen-activated protein kinases (MAPK) in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation.

METHODSImmunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism.

RESULTSThe abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 (CK18), a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2.

CONCLUSIONThe activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Animals ; Cryptorchidism ; enzymology ; pathology ; Disease Models, Animal ; Enzyme Activation ; Immunohistochemistry ; MAP Kinase Kinase 4 ; metabolism ; Macaca mulatta ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Scrotum ; enzymology ; p38 Mitogen-Activated Protein Kinases ; metabolism

To study the role of BAMBI in adipogenesis, we constructed lentivirus interfering vector targeting on porcine BAMBI, packaged and infected the porcine preadipocyte. The differentiation state of preadipocyte was detected by Oil Red O staining and Oil Red O extraction assay and the expression levels of adipogenic marker genes were detected by Real-time qPCR and Werstern bloting. Results show that BAMBI expression was significant decreased after lentivirus infection, which was repressed more than 60% by shRNA2. Moreover, knockdown BAMBI increased the lipid accumulation of porcine preadipocyte and improved the expression of PPARγ (peroxisome proliferator-activated receptorγ) and ap2 (adipocyte protein 2). In summary, these data indicated that BAMBI inhibited adipocyte differentiation by facilitating the phosphorylation of ERK1/2.
Adipocytes ; cytology ; Adipogenesis ; Animals ; Cell Differentiation ; Membrane Proteins ; metabolism ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; PPAR gamma ; metabolism ; Phosphorylation ; Swine

OBJECTIVETo study the expressions and clinical significances of p-extracellular regulated kinase(P-ERK)1/2 and matrix metalloproteinase-9(MMP-9)in cervical squamous cell carcinoma.

METHODSThe expressions of P-ERK1/2 and MMP-9 in 30 cases with chronic cervicitis, 45 cases with cervical intraepithelial neoplasia (CIN), and 58 cases with cervical squamous cell carcinoma were detected by immunohistochemical method.

RESULTSThe positive rates of P-ERK1/2 and MMP-9 in chronic cervicitis, CIN, and cervical squamous cell carcinoma were 0 and 0, 28.9% and 24.4%, 77.6% and 65.5%, respectively, showing significant differences among these three groups (χ(2)= 54.393,p=0.003;χ(2)=40.968,p=0.005). The positive rates of P-ERK1/2 and MMP-9 in patients at clinical stages 2-3, at G3, with lymphatic metastasis, or with a tumor diameter greater than 4 cm were significantly higher than those at clinical stage 1(p=0.015,p=0.002), at G1-G2(p=0.013,p=0.017), without lymphatic metastasis (p=0.017,p=0.021), or with a tumor diameter less or equal than 4 cm in cervical squamous cell carcinoma(p=0.008,p=0.004). There was a positive correlation between P-ERK1/2 and MMP-9 in cervical squamous cell carcinoma (χ(2)=8.955,p=0.006).

CONCLUSIONSThe expressions of P-ERK1/2 and MMP-9 increase gradually with the progression of cervical squamous cell carcinoma. The over expressions of P-ERK1/2 and MMP-9 may promote the infiltration of cervical squamous cell carcinoma and lymphatic metastasis, druing which these two enzymes may exert their effects in a synergistic manner.

Carcinoma, Squamous Cell ; enzymology ; pathology ; Female ; Humans ; Matrix Metalloproteinase 9 ; metabolism ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Uterine Cervical Neoplasms ; enzymology ; pathology

The study was aimed to investigate the molecular mechanisms of histone deacetylase inhibitor SAHA-induced apoptosis of acute myeloid leukemia cell line HL-60. The effect of SAHA on HL-60 cell proliferation was detected by MTT assay and the cell morphological changes were observed with Wright-Giemsa and Hoechst33342 staining. The cell cycle distribution was determined by flow cytometry and the expression of cell signaling proteins were detected by Western-blot analysis. The results showed that SAHA inhibited the proliferation of HL-60 cells in dose- and time-dependent manners, after 2 micromol/L SAHA exposure for 12 - 48 hours, the cell cycle was arrested at G(0)/G(1) phase and apoptotic cell death was confirmed by either defined apoptotic bodies stained by Hoechst33342, Western blot showed cleaved-PARP, which represents the activation of caspase 3. The Western blot analysis indicated the activation of two important survival signal pathways after SAHA treatment, the phosphorylation of Raf and its downstream ERK kinases were remarkable downregulated, whereas the phosphorylation of AKT and its downstream molecular mTOR were not changed. It is concluded that SAHA-induced apoptosis of HL-60 cells is mediated by inactivation of p44/42 MAPK signaling pathway.
Apoptosis ; drug effects ; HL-60 Cells ; Histone Deacetylase Inhibitors ; Humans ; Hydroxamic Acids ; pharmacology ; MAP Kinase Signaling System ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Signal Transduction

OBJECTIVETo observe the effect of electroacupuncture at Zusanli (ST 36) on phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) in the dorsal horn of spinal cord induced by plantar inflammation in the rat.

METHODSAll the rats were randomly divided into 5 groups: normal control group, simple electroacupuncture group, formalin group, formalin plus ipsilateral electroacupuncture group and formalin plus contralateral electroacupuncture group. The acute inflammation animal model was made by injection of 100 microL of 4% formalin into the right posterior foot pad. Electroacupuncture was given at "Zusanli" (ST 36) for 30 min, with sparse-dense waves, frequency 2-15 Hz, and intensity 2-3 mA. One and a half hours latter, the rats were killed under anesthesia, and pERK1/2 expression in the lumbar dorsal horn were investigated with immunohistochemical method.

RESULTSThe positive cells were rarely seen (6.45 +/- 1.05) in the superficial spinal cord in the control group; a few cells (14.07 +/- 3.19) in ipsilateral superficial spinal cord were found in the electroacupuncture group. The number of pERK1/2-positive neurons (26.57 +/- 4.93) in lamina I - II0 of the ipsilateral dorsal horn in the formalin group increased significantly. After electroacupuncture at ipsilateral Zusanli (ST 36), the number of positive cells (20.79 +/- 5.21) had a tendency to decrease, but with no statistically significant difference. However, after electroacupuncture at contralateral Zusanli (ST 36), the number of positive cells (14.75 +/- 3.03) significantly decreased as compared with the non-acupuncture group (P < 0.05).

CONCLUSIONThe inhibition of ERK1/2 phosphorylation in the spinal cord dorsal horn by electroacupuncture is possibly involved in acupuncture analgesic effect.

Acupuncture Analgesia ; Acupuncture Points ; Animals ; Electroacupuncture ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Phosphorylation ; Posterior Horn Cells ; enzymology ; Rats ; Rats, Sprague-Dawley

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

OBJECTIVETo detect protein expression of ERK(1), ERK(2), JNK(1), p38 and MEK(1), MEK(2) in human hepatocellular carcinoma and adjacent non-neoplastic liver.

METHODSIn 16 surgically resected hepatocellular carcinoma and para-carcinoma tissues, Western blotting was used to detect expression of ERK(1), ERK(2), JNK(1), p38 and MEK(1), MEK(2).

RESULTSIn all cases, ERK(1), ERK(2), p38 expression in hepatocellular carcinoma was significantly higher than that in para-carcinoma: integral optic density (IOD) of ERK(1) was 300 +/- 98 in carcinoma and 98 +/- 48 in para-carcinoma tissues (t = 2.519, P < 0.01); IOD of ERK(2) was 587 +/- 83 in carcinoma and 232 +/- 96 in para-carcinoma tissues (t = 2.745, P < 0.01); IOD of p38 was 270 +/- 85 in carcinoma and 107 +/- 88 in para-carcinoma tissues (t = 2.491, P < 0.01). JNK(1) expression in hepatocellular carcinoma was significantly lower than that in para-carcinoma; IOD of JNK(1) was 111 +/- 93 in carcinoma and 292 +/- 109 in para-carcinoma tissues (t = 2.473, P < 0.01). Protein levels of MEK(1) and MEK(2) in carcinoma were significantly higher than in para-carcinoma. IOD of MEK(1) was 1 418 +/- 244 in carcinoma and 806 +/- 90 in para-carcinoma tissues (t = 2.546, P < 0.01). IOD of MEK(2) was 1 041 +/- 122 in carcinoma and 468 +/- 40 in para-carcinoma tissues (t = 2.861, P < 0.01).

CONCLUSIONSERK(1), ERK(2), MEK(1) and MEK(2) in the signal transduction pathway for cell proliferation are significantly overexpressed and the expression of JNK(1) is lower in hepatocellular carcinoma. Their unbalance is one of the important reasons for the over growth and infinite proliferation of the hepatocellular carcinoma cell. The p38 and JNK(1) may be activated by different pathway.

Adult ; Aged ; Carcinoma, Hepatocellular ; enzymology ; Enzyme Activation ; Female ; Humans ; JNK Mitogen-Activated Protein Kinases ; Liver Neoplasms ; enzymology ; MAP Kinase Kinase 1 ; Male ; Middle Aged ; Mitogen-Activated Protein Kinase Kinases ; analysis ; Mitogen-Activated Protein Kinases ; metabolism ; Protein-Serine-Threonine Kinases ; analysis

In order to investigate the change of telomerase activity and phosphorylated (activated) extracellular regulated protein kinases (ERK) 1 and 2 in hepatocarcinomatous cell line SMMC7721 and leukemic cell line K562 proliferation inhibition and apoptosis, three kinds of chemotherapeutic drugs harringtonine (HRT), vincristine (VCR) and etoposide (VP-16) were selected as inducers; and MTT assay, flow cytometry analysis, telomeric repeat amplification protocol (TRAP) assay and bioluminescence analysis were used. The results showed that after treatment of HRT, VCR and VP-16 for 24 hours, the cell proliferation was inhibited, apoptosis was induced, and telomerase activity and the protein expression of phosphorylated ERK1/2 were down-regulated. In HRT treated groups, the descendent grade was the most obvious. It was concluded that the common molecular mechanism of these chemotherapeutic drugs killing SMMC7721 and K562 cell lines might be through inhibiting ERK signal transduction pathways, cutting down ERK activity, reducing the transcription of target genes of ERKs, then indirectly down-regulate telomerase activity, and cell apoptosis is the final result of durative loss of telomere.
Antineoplastic Agents ; pharmacology ; Apoptosis ; Carcinoma, Hepatocellular ; enzymology ; pathology ; Humans ; K562 Cells ; Leukemia ; enzymology ; pathology ; Liver Neoplasms ; enzymology ; pathology ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases ; metabolism ; Phosphorylation ; Telomerase ; metabolism ; Tumor Cells, Cultured