AIM: To systematically investigate if cGMP/cGMP- dependent protein kinase G (PKG) signaling pathway may participate in dendroaspis natriuretic peptide (DNP)-induced relaxation of gastric circular smooth muscle. METHOD...AIM: To systematically investigate if cGMP/cGMP- dependent protein kinase G (PKG) signaling pathway may participate in dendroaspis natriuretic peptide (DNP)-induced relaxation of gastric circular smooth muscle. METHODS: The content of cGMP in guinea pig gastric antral smooth muscle tissue and perfusion solution were measured using radioimmunoassay; spontaneous contraction of gastric antral circular muscles recorded using a 4-channel physiograph; and Ca2+-activated K+ currents (IK(Ca)) and spontaneous transient outward currents (STOCs) in isolated gastric antral myocytes were recorded using the whole-cell patch clamp technique. RESULTS: DNP markedly enhanced cGMP levels in gastric antral smooth muscle tissue and in the perfusion medium. DNP induced relaxation in gastricantral circular smooth muscle, which was inhibited by KT5823, a cGMP-dependent PKG inhibitor. DNP increased IK(Ca). This effect was almost completely blocked by KT5823, and partially blocked by LY83583, an inhibitor of guanylate cyclase to change the production of cGMP. DNP also increased STOCs. The effect of DNP on STOCs was abolished in the presence of KT5823, but not affected by KT-5720, a PKA-specific inhibitor. CONCLUSION: DNP activates IK(Ca) and relaxes guinea-pig gastric antral circular smooth muscle via the cGMP/PKG-dependent singling axis instead of cAMP/ PKA pathway.展开更多
Islets from RIP-PDE3B mice, exhibiting β-cell specific overexpression of the cAMP/cGMP-degrading enzyme phosphodiesterase 3B (PDE3B) and dysregulated insulin secretion, were subjected to microarray analysis. We show ...Islets from RIP-PDE3B mice, exhibiting β-cell specific overexpression of the cAMP/cGMP-degrading enzyme phosphodiesterase 3B (PDE3B) and dysregulated insulin secretion, were subjected to microarray analysis. We show that osteopontin (OPN) mRNA is increased in a dose-dependent manner in islets from RIP-PDE3B mice, as compared to wild-type islets. In addition, in silico analysis shows that PDE3B and OPN are interacting. Furthermore, OPN interacts with protein kinase CK2 ina distinct submodule of the protein-protein interaction network. We studied PDE3B and OPN proteins and, in some cases, also PDE1B and PDE4C, under conditions of relevance for insulin secretion. In the presence of forskolin, PDE inhibitors, insulin, or a protein kinase CK2 inhibitor, similar alterations in protein levels of PDE3B and OPN are shown. In summary, results from using a number of strategies demonstrate a connection between PDE3B and OPNas well as a role for protein kinase CK2 inpancreatic β-cells.展开更多
AIM: The goal of this study was to characterize the AlPreceptor, its possible signal transduction pathway and itsproliferative functions in human hepatoma cell line Bel 7402.METHODS: Cell proliferation enhanced by AFl...AIM: The goal of this study was to characterize the AlPreceptor, its possible signal transduction pathway and itsproliferative functions in human hepatoma cell line Bel 7402.METHODS: Cell proliferation enhanced by AFlP was detectedby MTT assay, 3H-thymidine incorporation and S-stsgepercentage of cell cycle analysis. With radioactive labeled 125 I-AFP for receptor binding assay; cAMP acctmuation, ProteinKinase A activity were detected by radioactive immunosorbentassay and the change of intracellular free calcium ([Ca2+ ], )was monitored by scanning fluorescence intensity under TCS-NT confocal microscope. The expression of oncxgenes N- ras,p53, and p21ras in the cultured cells in vitro were detected byNorthem blotting and Western blotting respectively.RESULTS: It was demonstrated that AFP enhanced theproliferation of human hepatoma Bel 7402 cell in a dosedependlent fashion asshown in MTT assay, 3H-thymidineincorporation and S-phase percentage up to 2-fold. Twosubtypes of AFP receptors were identified in the cells withKds of 1.3 x 10-9 mol. L-1 and 9.9 x 10-8 mol. L-1 respectively.Pretreatnent of cells with AFP resulted-in a significantincrease (625 %) in cAMP accumulation. The activity ofprotein kinase A activity were increased up to 37.5, 122.6,73.7 and 61.2 % at treatment time point 2, 6, 12 and 24hours. The level of intracellular calcium were elevated afterthe treatment of alpha-fetoprotsin and achieved to 204 % at 4min. The results also showed that AFP (20 mg. L-1 ) couldupregulate the expression of N-ras oncogenes and p53 andp21ras in Bel 7402 cells. In the later case, the alteration ware 81.1%(12 h) and 97.3 %(12 h) respectively compared with control.CONCLUSION: These results demonstrate that AFP is apotential growth factor to promote the proliferation of humanhepatoma Bel 7402 cells. Its growth-regulatory effects aremediated by its specific plasma membrane receptorscoupled with its transmembrane signaling transductionthrough the pathway of cAMP-PKA and intracellular calciumto regulate the expression of oncogenes.展开更多
AIM The existence and properties of alpha-fetoprotein (AFP) receptor on the surface of NIH 3T3 cells and the effects of AFP on cellular signal transduction pathway were investigated. METHODS The effect of AFP on the p...AIM The existence and properties of alpha-fetoprotein (AFP) receptor on the surface of NIH 3T3 cells and the effects of AFP on cellular signal transduction pathway were investigated. METHODS The effect of AFP on the proliferation of NIH 3T3 cells was measured by incorporation of 3H-TdR. Receptor-binding assay of 125I-AFP was performed to detect the properties of AFP receptor in NIH 3T3 cells. The influences of AFP on the [cAMP]i and the activities of protein kinase A (PKA) were determined. Western blot was used to detect the change of K-ras P21 protein expression. RESULTS The proliferation of NIH 3T3 cells treated with 0-80 mg/L of AFP was significantly enhanced. The Scatchard analysis indicated that there were two classes of binding sites with KD of 2.722×10-9M (Bmax=12810 sites per cell) and 8.931× 10-SM (Bmax=l19700 sites per cell) respectively. In the presence of AFP (20 mg/L), the content of cAMP and activities of PKA were significantly elevated . The level of K-ras P21 protein was upregulated by AFP at the concentration of 20 mg/L. The monoclonal antibody against AFP could reverse the effects of AFP on the cAMP content, PKA activity and the expression of K-ras p21 gene. CONCLUSION The effect of AFP on the cell proliferation was achieved by binding its receptor to trigger the signal transduction pathway of cAMP-PKA and alter the expression of K- ras p21 gene.展开更多
基金The National Natural Science Foundation of China, No. 30800382the Youth Science Foundation of Dalian to Professor Hui-Shu Guo, No. 2006B3NS218
文摘AIM: To systematically investigate if cGMP/cGMP- dependent protein kinase G (PKG) signaling pathway may participate in dendroaspis natriuretic peptide (DNP)-induced relaxation of gastric circular smooth muscle. METHODS: The content of cGMP in guinea pig gastric antral smooth muscle tissue and perfusion solution were measured using radioimmunoassay; spontaneous contraction of gastric antral circular muscles recorded using a 4-channel physiograph; and Ca2+-activated K+ currents (IK(Ca)) and spontaneous transient outward currents (STOCs) in isolated gastric antral myocytes were recorded using the whole-cell patch clamp technique. RESULTS: DNP markedly enhanced cGMP levels in gastric antral smooth muscle tissue and in the perfusion medium. DNP induced relaxation in gastricantral circular smooth muscle, which was inhibited by KT5823, a cGMP-dependent PKG inhibitor. DNP increased IK(Ca). This effect was almost completely blocked by KT5823, and partially blocked by LY83583, an inhibitor of guanylate cyclase to change the production of cGMP. DNP also increased STOCs. The effect of DNP on STOCs was abolished in the presence of KT5823, but not affected by KT-5720, a PKA-specific inhibitor. CONCLUSION: DNP activates IK(Ca) and relaxes guinea-pig gastric antral circular smooth muscle via the cGMP/PKG-dependent singling axis instead of cAMP/ PKA pathway.
文摘Islets from RIP-PDE3B mice, exhibiting β-cell specific overexpression of the cAMP/cGMP-degrading enzyme phosphodiesterase 3B (PDE3B) and dysregulated insulin secretion, were subjected to microarray analysis. We show that osteopontin (OPN) mRNA is increased in a dose-dependent manner in islets from RIP-PDE3B mice, as compared to wild-type islets. In addition, in silico analysis shows that PDE3B and OPN are interacting. Furthermore, OPN interacts with protein kinase CK2 ina distinct submodule of the protein-protein interaction network. We studied PDE3B and OPN proteins and, in some cases, also PDE1B and PDE4C, under conditions of relevance for insulin secretion. In the presence of forskolin, PDE inhibitors, insulin, or a protein kinase CK2 inhibitor, similar alterations in protein levels of PDE3B and OPN are shown. In summary, results from using a number of strategies demonstrate a connection between PDE3B and OPNas well as a role for protein kinase CK2 inpancreatic β-cells.
基金National Natural Science Foundation of China,No.39760077
文摘AIM: The goal of this study was to characterize the AlPreceptor, its possible signal transduction pathway and itsproliferative functions in human hepatoma cell line Bel 7402.METHODS: Cell proliferation enhanced by AFlP was detectedby MTT assay, 3H-thymidine incorporation and S-stsgepercentage of cell cycle analysis. With radioactive labeled 125 I-AFP for receptor binding assay; cAMP acctmuation, ProteinKinase A activity were detected by radioactive immunosorbentassay and the change of intracellular free calcium ([Ca2+ ], )was monitored by scanning fluorescence intensity under TCS-NT confocal microscope. The expression of oncxgenes N- ras,p53, and p21ras in the cultured cells in vitro were detected byNorthem blotting and Western blotting respectively.RESULTS: It was demonstrated that AFP enhanced theproliferation of human hepatoma Bel 7402 cell in a dosedependlent fashion asshown in MTT assay, 3H-thymidineincorporation and S-phase percentage up to 2-fold. Twosubtypes of AFP receptors were identified in the cells withKds of 1.3 x 10-9 mol. L-1 and 9.9 x 10-8 mol. L-1 respectively.Pretreatnent of cells with AFP resulted-in a significantincrease (625 %) in cAMP accumulation. The activity ofprotein kinase A activity were increased up to 37.5, 122.6,73.7 and 61.2 % at treatment time point 2, 6, 12 and 24hours. The level of intracellular calcium were elevated afterthe treatment of alpha-fetoprotsin and achieved to 204 % at 4min. The results also showed that AFP (20 mg. L-1 ) couldupregulate the expression of N-ras oncogenes and p53 andp21ras in Bel 7402 cells. In the later case, the alteration ware 81.1%(12 h) and 97.3 %(12 h) respectively compared with control.CONCLUSION: These results demonstrate that AFP is apotential growth factor to promote the proliferation of humanhepatoma Bel 7402 cells. Its growth-regulatory effects aremediated by its specific plasma membrane receptorscoupled with its transmembrane signaling transductionthrough the pathway of cAMP-PKA and intracellular calciumto regulate the expression of oncogenes.
基金This work was supported by National NaturalScience Fundation of China(No.39760077).
文摘AIM The existence and properties of alpha-fetoprotein (AFP) receptor on the surface of NIH 3T3 cells and the effects of AFP on cellular signal transduction pathway were investigated. METHODS The effect of AFP on the proliferation of NIH 3T3 cells was measured by incorporation of 3H-TdR. Receptor-binding assay of 125I-AFP was performed to detect the properties of AFP receptor in NIH 3T3 cells. The influences of AFP on the [cAMP]i and the activities of protein kinase A (PKA) were determined. Western blot was used to detect the change of K-ras P21 protein expression. RESULTS The proliferation of NIH 3T3 cells treated with 0-80 mg/L of AFP was significantly enhanced. The Scatchard analysis indicated that there were two classes of binding sites with KD of 2.722×10-9M (Bmax=12810 sites per cell) and 8.931× 10-SM (Bmax=l19700 sites per cell) respectively. In the presence of AFP (20 mg/L), the content of cAMP and activities of PKA were significantly elevated . The level of K-ras P21 protein was upregulated by AFP at the concentration of 20 mg/L. The monoclonal antibody against AFP could reverse the effects of AFP on the cAMP content, PKA activity and the expression of K-ras p21 gene. CONCLUSION The effect of AFP on the cell proliferation was achieved by binding its receptor to trigger the signal transduction pathway of cAMP-PKA and alter the expression of K- ras p21 gene.
