Calcitonin (CT), a polypeptide hormone, plays important roles in a variety of physiological processes. CT has been used clinically to treat osteoporosis and humoral hypercalcemia of malignancy. In order to clarify the pharmacological effects of CT in the kidney, we identified potential downstream genes induced by CT in the renal cells. Using a cDNA subtraction hybridization method, we identified connective tissue growth factor (CTGF) as a CT-induced gene in the porcine renal cell line, LLC-PK1. Furthermore, we found that CT-mediated induction of the gene was not inhibited by cycloheximide, which suggests that CTGF gene was not induced by an increased synthesis of regulating proteins. Therefore, CTGF is an immediate early gene. We further demonstrated that the regulation of CTGF gene expression by CT involved the ERK1/2 pathway, because PD98059, a MEK1 inhibitor, partially inhibited the mRNA expression of CTGF induced by CT. CT-induced CTGF protein expression was also observed in vivo. Our present findings suggest that CT induces the transcription of CTGF through ERK1/2 phosphorylation. We also identified twelve other genes induced by CT that, like CTGF, were related to wound healing. These results suggest that CT may have an effect on renal differentiation and wound healing in the kidney.
Animals ; Calcitonin/*pharmacology ; Cell Line ; Connective Tissue Growth Factor/*genetics/metabolism ; Female ; Kidney Tubules, Proximal/*enzymology/metabolism ; *MAP Kinase Signaling System ; Mice ; Mice, Inbred BALB C ; Mitogen-Activated Protein Kinase 1/*metabolism ; Mitogen-Activated Protein Kinase 3/*metabolism ; Phosphorylation ; Swine

Calcitonin (CT), a polypeptide hormone, plays important roles in a variety of physiological processes. CT has been used clinically to treat osteoporosis and humoral hypercalcemia of malignancy. In order to clarify the pharmacological effects of CT in the kidney, we identified potential downstream genes induced by CT in the renal cells. Using a cDNA subtraction hybridization method, we identified connective tissue growth factor (CTGF) as a CT-induced gene in the porcine renal cell line, LLC-PK1. Furthermore, we found that CT-mediated induction of the gene was not inhibited by cycloheximide, which suggests that CTGF gene was not induced by an increased synthesis of regulating proteins. Therefore, CTGF is an immediate early gene. We further demonstrated that the regulation of CTGF gene expression by CT involved the ERK1/2 pathway, because PD98059, a MEK1 inhibitor, partially inhibited the mRNA expression of CTGF induced by CT. CT-induced CTGF protein expression was also observed in vivo. Our present findings suggest that CT induces the transcription of CTGF through ERK1/2 phosphorylation. We also identified twelve other genes induced by CT that, like CTGF, were related to wound healing. These results suggest that CT may have an effect on renal differentiation and wound healing in the kidney.
Animals ; Calcitonin/*pharmacology ; Cell Line ; Connective Tissue Growth Factor/*genetics/metabolism ; Female ; Kidney Tubules, Proximal/*enzymology/metabolism ; *MAP Kinase Signaling System ; Mice ; Mice, Inbred BALB C ; Mitogen-Activated Protein Kinase 1/*metabolism ; Mitogen-Activated Protein Kinase 3/*metabolism ; Phosphorylation ; Swine

In order to investigate the changes in the expression of extracellular signal-regulated kinase (ERK1/ERK2) and angiotensin-converting enzyme (ACE) in the patients with atrial fibrillation (AF), 52 patients with rheumatic heart diseases were examined. Nineteen patients had chronic persistent AF (AF > or = 6 months, CAF), 12 patients had paroxymal AF (PAF) and 21 patients had no history of AF. The ERK expression was detected at the mRNA level by reverse transcription polymerase chain reaction, at the protein level by Western blotting and at atrial tissue level by immunohistochemistry. ERK-activating kinases (MEK1/2) and ACE were determined by Western blotting techniques. The expression of ERK2-mRNA was increased in the patients with CAF (74 +/- 19 U vs sinus rhythm: 32 +/- 24 U, P < 0.05). Activated ERK1/ERK2 and MEK1/2 were increased to more than 150% in the patients with AF compared to those with sinus rhythm. No significant difference between CAF and PAF was found. The expression of ACE was three-fold increased in the patients with CAF compared to those with sinus rhythm. Patients with AF showed an increased expression of ERK1/ERK2 in atrial interstitial cells and marked atrial fibrosis. An ACE-dependent increase in the amounts of activated ERK1/ERK2 in atrial interstitial cells may be one of molecular mechanisms for the development of atrial fibrosis in the patients with AF. These findings may have important impact on the treatment of AF.
Adult ; Aged ; Atrial Fibrillation ; enzymology ; etiology ; Female ; Gene Expression ; Heart Atria ; enzymology ; Humans ; Male ; Middle Aged ; Mitogen-Activated Protein Kinase 1 ; genetics ; metabolism ; Mitogen-Activated Protein Kinase 3 ; genetics ; metabolism ; Peptidyl-Dipeptidase A ; genetics ; metabolism ; Rheumatic Heart Disease ; complications

OBJECTIVETo observe influence of electroacupuncture (EA) on phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) in spinal cord dorsal horn (SCDH) in rats with acute inflammatory pain induced by complete Freund's adjuvant (CFA), further elucidate the immediate analgesic mechanism of EA via cellular signal transduction.

METHODSFifty-three healthy male SD rats were divided into two batches. The inflammatory pain models of the first batch of 23 rats were established by using CFA. The changes of the paw withdrawal thresholds (PWTs) of rats were observed and positive cells of p-ERK1/2 in affected SCDH were detected by using immunohistochemistry method. The second batch of 30 rats were randomly divided into a blank control group (N group), CFA group and EA group, 10 rats in each group. The rats of CFA group and EA group were induced inflammatory pain by using CFA, and the EA group was treated with EA at 5.5 h after the model establishment. The changes of PWTs and the positive cells of p-ERK1/2 in SCDH were observed.

RESULTSThe PWTs of the first batch of rats obviously decreased at 5 h, 3 d, 7 d and 14 d after CFA administration (all P< 0.01). However, the p-ERK1/2 positive cells in affected SCDH only increased at 5 h after CFA-injection and returned to normality at 3 d after the model establishment. In the second batch, compared with that of N group at the same time point, PWTs of rats in both CFA and EA group obviously decreased after the model establishment (both P<0.01). PWTs of rats in EA group which accepted EA treatment once were longer than those before EA treatment and corresponding PWTs in CFA group at the same time point (both P<0.01). Moreover, the numbers of p-ERK1/2 positive cells of affected SCDH increased significantly in CFA group at 6 h after the model establishment (P<0.01), however, which were decreased significantly in EA group (P<0.01).

CONCLUSIONInhibiting ERK1/2 activation of SCDH may be one of the pivotal mechanism of cellular signal transduction of the immediate analgesic effect educed by EA.

Acupuncture Analgesia ; Animals ; Back Pain ; chemically induced ; enzymology ; genetics ; therapy ; Electroacupuncture ; Freund's Adjuvant ; adverse effects ; Humans ; Male ; Mitogen-Activated Protein Kinase 1 ; genetics ; metabolism ; Mitogen-Activated Protein Kinase 3 ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spine ; enzymology

OBJECTIVETo investigate the effect of cytoskeleton reorganization inhibition with RNA interference on the activation of extracellular signal-regulated kinase (ERK1/2) in primary osteoblasts induced by fluid shear stress (FSS).

METHODSBALB/c mouse primary cultured osteoblasts were isolated by enzyme digestion technique. Osteoblasts were treated with LIM domain kinase 2 (LIM-2) specific siRNA or negative control siRNA, and then were loaded or unloaded by FSS of 1.2 Pa for 0, 5, 15, 30 and 60 min, respectively. The Western blotting was performed to detect the protein expression levels of P-ERK1/2 and ERK1/2, respectively. Two-way ANOVA and one-way ANOVA were used in data analysis.

RESULTSFSS loading for different time (0, 5, 15, 30, 60 min) treated with negative RNA inteference had significant effect on the levels of P-ERK/ERK ratio (0.047 ± 0.031, 0.253 ± 0.137, 0.390 ± 0.155, 0.613 ± 0.123, 0.680 ± 0.108, respectively, P < 0.01). Statistical analysis showed that there was significant interaction between FSS and cytoskeleton reorganization inhibition treated with RNA inteference on the levels of P-ERK/ERK ratio (P < 0.01). The levels of P-ERK/ERK ratio increased when osteoblasts were loaded for 5 - 15 min (0.623 ± 0.129 and 0.623 ± 0.064, respectively, P < 0.05) and returned to baseline at 30 min (0.333 ± 0.086), and then reached the peak at 60 min (0.667 ± 0.064, P < 0.01).

CONCLUSIONSFSS could activate ERK1/2 rapidly in primary cultured osteoblasts. Cytoskeleton reorganization inhibition treated with RNA interference speeded-up the activation of ERK1/2 by FSS, which could increase the sensitivity of ERK1/2 to FSS.

Animals ; Cells, Cultured ; Cytoskeleton ; metabolism ; physiology ; Lim Kinases ; genetics ; metabolism ; Mechanotransduction, Cellular ; Mice ; Mice, Inbred BALB C ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Osteoblasts ; cytology ; enzymology ; Phosphorylation ; RNA Interference ; RNA, Small Interfering ; Stress, Mechanical

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

Fluid shear stress plays an important role in many physiological and pathophysiological processes of the cardiovascular system. It modulates vascular function and structure via stimulating mechanosensitive endothelial cell signal events. Previous studies have identified that the exposure of vascular endothelial cells to fluid mechanical forces can modulate the expressions of many genes, including IL-8 gene. In order to gain an insight into the role of extracellular signal regulated kinase (ERK1/2) signal pathway in the expression of IL-8 mRNA in human umbilical vein endothelial cells (HUVECs) under the stimulation by low shear stress (4.20 dyne/cm2), we employed Western blot to measure phosphorylation of ERK1/2 and used quantitative reversal transcription-polymerase chain reaction (qRT-PCR) to assay the expression of IL-8 mRNA. The results showed: (1) Shear stress could activate ERK1/2 with a rapid, biphasic time course (maximum by 10 min and basal by 2 h); the treatment of HUVECs with Genistein (a highly specific inhibitor of tyrosine protein kinase, TPK) or PD98059 (the inhibitor of mitogen-activated protein/extracellular signal regulated kinase kinase, MEK) culd prevent shear-dependent activation of ERK1/2; (2) When treated with Genistein or PD98059, significant inhibition of IL-8 mRNA expression induced by low shear stress was observed in HUVECs. This in vitro study demonstrates that ERK1/2 plays an important role in IL-8 mRNA expression induced by low shear stress.
Cells, Cultured ; Endothelium, Vascular ; cytology ; metabolism ; Humans ; Interleukin-8 ; biosynthesis ; genetics ; Mitogen-Activated Protein Kinase 1 ; physiology ; Mitogen-Activated Protein Kinase 3 ; physiology ; RNA, Messenger ; biosynthesis ; genetics ; Signal Transduction ; Stress, Mechanical ; Umbilical Veins ; cytology

OBJECTIVETo investigate the expression of Smad4 in non-small cell lung cancer (NSCLC), its correlation with MAPK (mitogen activated protein kinase) and their clinical significance in NSCLC.

METHODSWestern blotting and RT-PCR were employed to test 42 resected lung cancers and normal lung tissues for the expression of Smad4. Imunohistochemistry was used to detect Smad4 and subtribes of MAPK in 71 paraffin samples.

RESULTSThe level of protein and mRNA expression of Smad4 in lung cancer tissues were 0.2092 +/- 0.1308 and 0.3986 +/- 0. 1982, respectively, lower than those in normal tissues (0.7852 +/- 0.4386 and 1.1206 +/- 0.6772, P < 0.05). The expression of p38, ERK1 and Smad4 was associated with TNM staging (P = 0.000, 0.000 and 0.005, respectively) and JNK1 with tumor location (P = 0.028) and staging (P = 0.000). There was a correlation between p38 and Smad4 (P = 0.000). The expression of Smad4 (P = 0.0001), p38 (P = 0.0000) and JNK1 (P = 0.0208), tumor differentiation (P = 0.0059) and staging (P = 0.0000) were significantly correlated with prognosis of NSCLC by univariate analysis. Smad4 (P = 0.019), p38 (P = 0.044), tumor differentiation (P = 0.003), and staging (P = 0.020) were correlated with prognosis tested by multivariable analysis. Taking p38 and Smad4 together, we found that the negative expression of p38 and positive expression of Smad4 were associated with a better prognosis of NSCLC (P = 0.000).

CONCLUSIONSmad4 could be of importance for the initiation and development of NSCLC. There is a significant correlation between main proteins of TGF-beta/smad4 and those of ras-MAPK signal transduction pathways. The expression of Smad4 is inhibited by p38. Smad4, as well as p38, tumor differentiation and staging can be used as prognostic factors of NSCLC.

Adult ; Aged ; Blotting, Western ; Carcinoma, Non-Small-Cell Lung ; metabolism ; pathology ; Cell Differentiation ; Female ; Humans ; Lung Neoplasms ; genetics ; metabolism ; pathology ; Male ; Middle Aged ; Mitogen-Activated Protein Kinase 3 ; genetics ; metabolism ; Mitogen-Activated Protein Kinase 8 ; genetics ; metabolism ; Mitogen-Activated Protein Kinases ; genetics ; metabolism ; Neoplasm Staging ; Prognosis ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; Smad4 Protein ; genetics ; metabolism ; physiology ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism

Epidermal keratinocyte differentiation is a tightly regulated stepwise process that requires protein kinase C (PKC) activation. Studies on cultured mouse keraitnocytes induced to differentiate with Ca2+ have indirectly implicated the involvement of PKC alpha isoform. When PKC alpha was overexpressed in undifferentiated keratinocytes using adenoviral system, expressions of differentiation markers such as loricrin, filaggrin, keratin 1 (MK1) and keratin 10 (MK10) were increased, and ERK1/2 phosphorylation was concurrently induced without change of other MAPK such as p38 MAPK and JNK1/2. Similarly, transfection of PKC alphakinase active mutant (PKC alpha- CAT) in the undifferentiated keratinocyte, but not PKC beta-CAT, also increased differentiation marker expressions. On the other hand, PKC alphadominant negative mutant (PKC beta-KR) reduced Ca2+ -mediated differentiation marker expressions, while PKC beta-KR did not, suggesting that PKC alphais responsible for keratinocyte differentiation. When downstream pathway of PKC alphain Ca2+ - mediated differentiation was examined, ERK1/2, p38 MAPK and JNK1/2 phosphorylations were increased by Ca2+ shift. Treatment of keratinocytes with PD98059, MEK inhibitor, and SB20358, p38 MAPK inhibitor, before Ca2+ shift induced morphological changes and reduced expressions of differentiation markers, but treatment with SP60012, JNK1/2 inhibitor, did not change at all. Dominant negative mutants of ERK1/2 and p38 MAPK also inhibited the expressions of differentiation marker expressions in Ca2+ shifted cells. The above results indicate that both ERK1/2 and p38 MAPK may be involved in Ca2+- mediated differentiation, and that only ERK1/2 pathway is specific for PKCa-mediated differentiation in mouse keratinocytes.
Animals ; Calcium/pharmacology/physiology ; Cell Differentiation/physiology ; Intermediate Filament Proteins/analysis/metabolism ; Keratinocytes/cytology/*enzymology ; Membrane Proteins/analysis/metabolism ; Mice ; Mitogen-Activated Protein Kinase 1/*metabolism ; Mitogen-Activated Protein Kinase 3/*metabolism ; Phosphorylation ; Protein Kinase C/genetics/*physiology ; Research Support, Non-U.S. Gov't ; p38 Mitogen-Activated Protein Kinases/metabolism

OBJECTIVETo investigate the effects of protein tyrosine phosphatase-SHP2 and dual-specificity MAPK phosphatase-MKP5 on the activation of MAPKs and cell invasion induced by P2Y purinergic receptor in human prostate cancer cell lines with different metastatic potentials.

METHODSThe wide type (-wt) SHP2, mutant type (-cs) SHP2 and wide type (-wt) MKP5 cDNA expression vectors were constructed and stably transfected into 1E8 cells (highly metastatic) and/or 2B4 cells (non-metastatic). The tyrosine phosphorylation of SHP2 was examined by immunoprecipitation. The activation of ERK1/2 and p38 induced by P2Y receptor agonist ATP was analyzed by Western blot with phospho-specific antibodies against the dually phosphorylated, active forms of ERK1/2 and p38. The in-vitro invasive ability through Matrigel was measured by boyden-chamber assay.

RESULTSATP induced significant SHP2 phosphorylation, which was stronger and lasted longer in 1E8 than in 2B4. SHP2-wt enhanced the ERK1/2 activation induced by ATP in 2B4 cells, while SHP2-cs delayed and decreased this effect in 1E8 cells. Both SHP2-wt and SHP2-cs had no obvious influence on p38 activation. ATP stimulated cell invasion of both 1E8 and 2B4, while transfection of SHP2-wt into 2B4 cells further increased the invasive-stimulating ability of ATP (18.7% increase compared with ATP treatment alone). Transfection of SHP2-cs into 1E8 cells, however, antagonized the invasive-stimulating ability of ATP (40.9% decrease compared with ATP treated group). Up-regulation of MKP5-wt inhibited phosphorylation of p38 by ATP and reduced cell invasion stimulated by ATP (22.4% and 28.7% decrease compared with ATP treated group of 1E8 and 2B4, respectively).

CONCLUSIONSBoth SHP2 and MKP5 play some roles in P2Y receptor-mediated activation of MEK/ERK, p38 signaling pathways and prostate cancer invasion. SHP2 positively regulates ERK activation and prostate cancer invasion, whereas MKP5 inhibits the invasion by suppressing p38 activation.

Adenosine Triphosphate ; pharmacology ; Cell Line, Tumor ; DNA, Complementary ; genetics ; Dual-Specificity Phosphatases ; Genetic Vectors ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Mitogen-Activated Protein Kinase Phosphatases ; Neoplasm Invasiveness ; Phosphorylation ; Prostatic Neoplasms ; metabolism ; pathology ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; Protein Tyrosine Phosphatases ; genetics ; metabolism ; Receptors, Purinergic P2 ; physiology ; Signal Transduction ; Transfection ; p38 Mitogen-Activated Protein Kinases ; metabolism