Humans ; Isotope Labeling ; Nuclear Magnetic Resonance, Biomolecular ; Protein Domains ; src-Family Kinases ; chemistry

Objective: To investigate whether inflammatory factor tumor necrosis factor-α (TNF-α) is involved in the electrical remodeling of cardiomyocytes by regulating ultra-rapid delayed rectifier K(+) current (I(kur)) and the role of Src kinase. Methods: H9c2 cells, embryonic cardiomyocytes of rat, were cultured in Dulbecco's modified Eagle's medium (DMEM) and atrium-derived HL-1 cells were cultured in Claycomb medium. Both H9c2 and HL-1 cells were cultured at 37 ℃ with 5% CO(2). Cells cultured in normal conditions without additional treatment served as control group. Experimental groups were treated with different concentration of TNF-α (25 or 50 or 100 ng/ml) for 24 hours. To study whether Src specific inhibitor PP1 could abrogate the effect of TNF-α, cells were pre-treated with 10 μmol/L PP1 for 1 hour, followed by TNF-α (100 ng/ml) for 24 hours. Western blot and the whole cell patch clamp technique were used to detect the protein expression of Kv1.5 and Src and I(kur) in each group. Results: (1) In H9c2 cells, high concentration of TNF-α treatment (100 ng/ml) significantly reduced the Kv1.5 protein expression compared with control group and TNF-α 25 ng/ml group (both P<0.05). Compared with control group, the expression of p-Src protein was higher in 25 ng/ml, 50 ng/ml, 100 ng/ml TNF-α group (all P<0.05), but there was no statistical difference in the expression of Src protein among groups (P>0.05). In addition, the current density of I(kur) was decreased in 50 ng/ml, 100 ng/ml TNF-α group (both P<0.05). Furthermore, the expression of Kv1.5 protein and the current density of I(kur) were increased in PP1+TNF-α group compared with TNF-α 100 ng/ml group (both P<0.05). There was no statistical difference in the expression of Kv1.5 protein and the current density of I(kur) between the control group and PP1+TNF-α group (both P>0.05). (2) In atrium-derived HL-1 cells, the expression of Kv1.5 protein was reduced in 100 ng/ml TNF-α group compared with control group and TNF-α 25 ng/ml group (both P<0.01). In addition, the expression of p-Src protein was increased in TNF-α 100 ng/ml group compared with control group (P<0.05), but there was no statistical difference in the protein expression of Src among groups (P>0.05). The expression of Kv1.5 protein was increased in PP1+TNF-α group compared with TNF-α 100 ng/ml group (P<0.05). Conclusion: TNF-α is involved in the pathogenesis of atrial fibrillation, probably via decreasing I(kur) current density in atrium-derived myocytes through the activation of Src kinase.
Animals ; Down-Regulation ; Heart Atria ; Myocytes, Cardiac ; Rats ; Tumor Necrosis Factor-alpha ; src-Family Kinases

OBJECTIVETo investigate the effect of Src kinase inhibitor PP2 on hypoxia/reoxygenation (H/R) injury in rat astrocytes in vitro.

METHODSIn vitro cultured rat astrocytes were exposed to hypoxia for 8 h followed by reoxygenation for 24 h with or without pretreatment with PP2 (10 µmol/L) for 24 h before H/R injury. MTT assay and flow cytometry were used to detect the viability and apoptosis of the exposed astrocytes, respectively, and the protein expressions of Src, Bax, and Bcl-2 in the cells were determined using Western blotting.

RESULTSPP2 pretreatment significantly increased the viability and decreased the apoptosis rate of rat astrocytes exposed to H/R injury (P<0.01). Western blotting showed that H/R injury caused increased expression of Src kinase, which was lowered by PP2 pretreatment. The ratio of Bax/bcl-2 in the astrocytes increased after H/R injury, and was significantly decreased by PP2 pretreatment (P<0.01).

CONCLUSIONPP2 protects rat astrocytes from H/R injury possibly by inhibiting the expression of Src kinase and activating the anti-apoptotic mechanisms in the cells.

Animals ; Apoptosis ; Astrocytes ; pathology ; Cell Hypoxia ; Cells, Cultured ; Flow Cytometry ; Pyrimidines ; pharmacology ; Rats ; src-Family Kinases ; antagonists & inhibitors

OBJECTIVETo investigate the effect of Src kinase inhibitor PP2 on intercellular communication of gap junction in breast cancer cells.

METHODSCultured breast cancer Hs578T cells were treated with various concentrations of pp2 (0,1,2,4,8,16,32 μmol/L) for 24h. Cell growth was determined by MTT assay; dye spread in Hs578T cells was measured by Parachute assay; and the expression of Src kinase in Hs578T cells was detected by Western blot.

RESULTSMTT assay showed that the survive rate of Hs578T cells treated with PP2 (1 ≊ 8 μmol/L) was 98% ± 3% ≊ 94 % ± 4%. Parachute assay showed that compared to control group the standard normalized dye spread rates of Hs578T cells treated with 1,2,4 and 8 μmol/L PP2 were 1.60 ± 0.08,2.00 ± 0.05,2.20 ± 0.05 and 2.70 ± 0.09,respectively (all P<0.01). Moreover,compared to control group at the same time points,the standard normalized dye spread of Hs578T cells treated with 8 μmol/L PP2 for 6,12 and 24 h were 1.4 ± 0.05,1.7 ± 0.06,and 2.2 ± 0.07,respectively (all P<0.01). Western blot showed that the expression ratios of Src kinase/β-actin of Hs578T cells treated with 1,2,4 and 8 μmol/L PP2 for 24 h were 0.93 ± 0.02,0.70 ± 0.09,0.66 ± 0.09 and 0.36 ± 0.10,which were significantly inhibited compared with control group (P<0.05 or 0.01). And the expression ratio of Src kinase/β-actin of Hs578T cells treated with 8 μmol/L PP2 for 6,12 and 24h was 0.82 ± 0.03,0.66 ± 0.08 and 0.59 ±0.09, which were all inhibited significantly compared to control group (P<0.01).

CONCLUSIONPP2 enhances the gap junction function in breast cancer Hs578T cells, which is probably related to the inhibition of Src kinase.

Breast Neoplasms ; pathology ; Cell Line, Tumor ; Female ; Gap Junctions ; drug effects ; Humans ; Pyrimidines ; administration & dosage ; pharmacology ; src-Family Kinases ; metabolism

OBJECTIVETo investigate the role of Src family kinases (Fgr, Hck, Lyn) and the major protein kinase C substrate SSeCKS in non-alcoholic steatohepatitis (NASH) and determine the possible mechanism regulating differential expression.

METHODSKupffer cells were stimulated with CCL4 and effect on SSeCKS, Hck, Fgr, and Lyn expression was detected by real-time reverse transcription-PCR. Male Sprague-Dawley rats were used to create a NASH model by feeing a high fat diet. The modeled rats were divided into a model group and a normal group. After sacrifice, the extent of hepatic steatosis and inflammation was assessed, and the expression levels of SSeCKS and Hck, Fgr, Lyn were detected by immunohistochemical staining.

RESULTSExpression of Lyn and Hck was decreased in the CCL4-stimulated Kupffer cells and the change in expression level was positively associated with levels of inflammatory stimuli (P < 0.01). The change in expression of SSeCKS in the CCL4-stimulated Kupffer cells was negatively correlated with inflammatory stimuli (P < 0.01). Fgr expression was very low in the unstimulated Kupffer cells and was not affected by the exposure to inflammatory stimuli. The number of inflammatory cells in the liver tissues of rars were negatively correlated with expression of Lyn, Hck and SSeCKS (P < 0.01), with low negative correlation for Lyn (r =-0.398, P < 0.01) and moderate negative correlation for Hck (r=-0.508, P < 0.01); the Lyn and Hck expression levels were highly positively correlated (r =0.942, P < 0.01).

CONCLUSIONSrc family kinases (Lyn, Hck and Fgr) and SSeCKS are involved in development and progression of NASH, and their differential expression patterns are associated to a certain extent. The factors may represent potential targets of therapy for NASH-related inflammation.

A Kinase Anchor Proteins ; Animals ; Cell Cycle Proteins ; Fatty Liver, Alcoholic ; Inflammation ; Male ; Rats ; Rats, Sprague-Dawley ; src-Family Kinases

Recent studies showed that Eph/Ephrin tyrosine kinase family plays an important role in the development and functional maintenance of the nervous system, but its function in the sympathetic nervous system is still obscure. In the present study, we examined the effect of Eph/Ephrin-B1 signaling on the whole-cell currents mediated by either alpha7 or alpha3-nicotinic acetylcholine receptors (nAChRs) in acutly dissociated ciliary ganglion (CG) neurons. Firstly, we detected the effect of Ephrin-B1 on nAChRs currents. The neurons were randomly divided into control group, Ephrin-B1Fc-treated group that was stimulated by recombinant Ephrin-B1Fc, IgG-treated group, and Ephrin-B1-treated group. Secondly, we studied the regulatory mechanism of Ephrin-B1Fc on nAChRs currents. The neurons were randomly divided into control group, Ephrin-B1Fc-treated group, PP2 (inhibitor of Src tyrosine kinase) or PD98095 (antagonist of mitogen-activated protein kinase)-treated group, Ephrin-B1Fc + PP2 or PD98095-treated group. The results showed that there was no significant difference between the currents in control group, IgG-treated group and Ephrin-B1-treated group, but Ephrin-B1Fc significantly suppressed both alpha3-nAChRs and alpha7-nAChRs-mediated currents (P=0.002, P=0.003). Pretreatment with PP2 or PD98095 could partially rescue the Ephrin-B1Fc-induced suppression of currents mediated by alpha3-nAChRs or alpha7-nAChRs respectively. These results suggest that the Eph/Ephrin-B1 signaling may inhibit alpha3-nAChRs and alpha7-nAChRs-mediated currents on CG neurons, involving Src tyrosine kinase and mitogen-activated protein kinase signaling in the regulation of sympathetic nervous system.
Ephrin-B1 ; metabolism ; Ganglia, Parasympathetic ; enzymology ; Mitogen-Activated Protein Kinases ; metabolism ; Neurons ; enzymology ; Receptors, Nicotinic ; metabolism ; Signal Transduction ; alpha7 Nicotinic Acetylcholine Receptor ; metabolism ; src-Family Kinases ; metabolism

Excessive influx and the subsequent rapid cytosolic elevation of Ca²⁺ in neurons is the major cause to induce hyperexcitability and irreversible cell damage although it is an essential ion for cellular signalings. Therefore, most neurons exhibit several cellular mechanisms to homeostatically regulate cytosolic Ca²⁺ level in normal as well as pathological conditions. Delayed rectifier K⁺ channels (I(DR) channels) play a role to suppress membrane excitability by inducing K⁺ outflow in various conditions, indicating their potential role in preventing pathogenic conditions and cell damage under Ca²⁺-mediated excitotoxic conditions. In the present study, we electrophysiologically evaluated the response of IDR channels to hyperexcitable conditions induced by high Ca²⁺ pretreatment (3.6 mM, for 24 hours) in cultured hippocampal neurons. In results, high Ca²⁺-treatment significantly increased the amplitude of IDR without changes of gating kinetics. Nimodipine but not APV blocked Ca²⁺-induced IDR enhancement, confirming that the change of I(DR) might be targeted by Ca²⁺ influx through voltage-dependent Ca²⁺ channels (VDCCs) rather than NMDA receptors (NMDARs). The VDCC-mediated I(DR) enhancement was not affected by either Ca²⁺-induced Ca²⁺ release (CICR) or small conductance Ca²⁺-activated K⁺ channels (SK channels). Furthermore, PP2 but not H89 completely abolished I(DR) enhancement under high Ca²⁺ condition, indicating that the activation of Src family tyrosine kinases (SFKs) is required for Ca²⁺-mediated I(DR) enhancement. Thus, SFKs may be sensitive to excessive Ca²⁺ influx through VDCCs and enhance I(DR) to activate a neuroprotective mechanism against Ca²⁺-mediated hyperexcitability in neurons.
Animals ; Calcium Channels ; Cytosol ; Humans ; Kinetics ; Membranes ; Neurons* ; Nimodipine ; Protein-Tyrosine Kinases* ; Rats* ; Receptors, N-Methyl-D-Aspartate ; src-Family Kinases ; Tyrosine*

Intracellular signal transduction plays an important role in the process of cellular metabolism, segmentation, differentiation, biological behaviour and cell death. Overactive signal transduction relates to tumor development and progression. Signaling pathways operated by protein tyrosine kinases (PTKs) will be illuminated here briefly. The Ras/Raf/MAPK and PI-3K/Akt pathways through receptor protein tyrosine kinases (RTKs), the Src, Bcr-Abl and JAK/STAT pathways by non-receptor protein tyrosine kinases (nrPTKs) are shown separately. Antitumor agents targeting the key proteins involved in the above five signalling routes are also summarized in this review.
Animals ; Antineoplastic Agents ; pharmacology ; Humans ; Phosphatidylinositol 3-Kinases ; metabolism ; Protein-Tyrosine Kinases ; metabolism ; Receptor Protein-Tyrosine Kinases ; metabolism ; STAT Transcription Factors ; metabolism ; Signal Transduction ; drug effects ; ras Proteins ; metabolism ; src-Family Kinases ; metabolism

BACKGROUND: The Src family kinases (SFKs) are involved in multiple aspects of tumorigenesis, such as, proliferation, migration, and angiogenesis, and are involved in the generation and progression of many types of tumors. Furthermore, dasatinib, a general SFKs inhibitor was recently approved for use in chronic myeloid leukemia. This study was performed to evaluate the expression of Lyn, a member of the SFKs, in osteosarcoma tissues. METHODS: One hundred and sixteen patients with osteoblastic osteosarcoma were selected for Lyn expression analysis. The correlation between Lyn expression in tumor sections and patients' clinicopathologic characteristics and the prognostic significance of Lyn expression were evaluated. RESULTS: Lyn was found to be expressed in 52 of the 116 patients (44.8%), and Lyn positive tumor was found to be significantly associated with a lytic tumor pattern on plain radiographs (p = 0.04). Furthermore, those positive for Lyn showed longer metastasis free survival (5-year metastasis free survival, 65.2% for Lyn positive and 46.8% for Lyn negative; p = 0.06), though this was only marginally significant. CONCLUSIONS: Lyn was found to be overexpressed in osteosarcoma tissues, and this overexpression was found to be correlated with osteolysis.
Cell Transformation, Neoplastic ; Humans ; Immunohistochemistry ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; Neoplasm Metastasis ; Osteoblasts ; Osteolysis ; Osteosarcoma ; Pyrimidines ; src-Family Kinases ; Thiazoles ; Dasatinib

PURPOSE: We performed experiments to investigate the change in cellular signaling that occurs during the transformation of a normal cell to a cell capable of cancerous growth, and we did so by using the NIH 3T3 cells that were transformed by transfection with the v-Ha-ras oncogene. MATERIALS AND METHODS: Parental and v-Ha-ras transfected NIH 3T3 cells were chosen as test systems. The siRNA transfections were performed using Lipofectamine 2000. The cell proliferation reagent WST-1 was used for the quantitative determination of cellular proliferation. Immunoblot analysis was performed using the ECL-Plus chemiluminescent system and a KODAK Image Station 4000R. RESULTS: The v-Ha-ras-transformed cells were found to be significantly more resistant to PP2 treatment, which is a potent inhibitor of the Src family tyrosine kinases, than were the parental cells at earlier times after treatment. However, PP2 induced growth arrest and the senescence-like phenotypes in both cell lines after longer treatment. Furthermore, the Raf-1 kinase of the v-Ha-ras-transformed cells was not affected by the expressed level of Sprouty proteins, which are negative regulators of the MAPK pathway, as evidenced by the failure of siRNA-mediated knockdown of Spry4 to activate Raf-1 kinase. Dephostatin (a tyrosine phosphatase inhibitor) effectively inhibited the proliferation of the v-Ha-ras transformed cells, whereas dephostatin had only a small effect on the parental cells' proliferation. This implied an inhibitory role for tyrosine phosphatase that is specific to the signaling pathway in the v-Ha-ras transformed cells. CONCLUSION: Taken together, our results show that the sustained activation of the oncogenic pathways through their resistance to negative feedback regulation might contribute to the transformation of NIH 3T3 cells.
Cell Line ; Cell Proliferation ; Genes, ras ; Humans ; Hydroquinones ; Lipids ; NIH 3T3 Cells ; Parents ; Phenotype ; Proteins ; Proto-Oncogene Proteins c-raf ; RNA, Small Interfering ; src-Family Kinases ; Transfection ; Tyrosine