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...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 x 10(-9)M (Bmax=12810 sites per cell) and 8.931 x 10(-8)M (Bmax=119700 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
OBJECTIVE: To investigate the expression of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) and the effect of lipopolysaccharide (LPS) on their expression in cultured endothelial cells. METHODS: Total RNA ...OBJECTIVE: To investigate the expression of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) and the effect of lipopolysaccharide (LPS) on their expression in cultured endothelial cells. METHODS: Total RNA was extracted from ECV304 cells and isolated human umbilical vein endothelial cells (HUVECs) exposed to LPS, respectively. The quantification of TLR2 and TLR4 mRNA in HUVECs and EVC304 cells was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: ECV304 cells and HUVECs were able to express TLR2 and TLR4 mRNA, but the expression levels of TLR4 appeared to be stronger than those of TLR2. LPS could upregulate the expression levels of TLR4 obviously, whereas it had no effect on the expression level of TLR2. CONCLUSIONS: Our data indicate that TLR4 may be the LPS signal transducer in endothelial cells and plays important roles in the cell activation of LPS. The ECV304 cell line is a better experimental model than isolated HUVECs in the research of endothelial cells.展开更多
The nucleotide sequence deduced from the amino acid sequence of the scorpion insectotoxin AaIT was chemically synthesized and was expressed in Escherichia coli. The authenticity of this in vitro expressed peptide was ...The nucleotide sequence deduced from the amino acid sequence of the scorpion insectotoxin AaIT was chemically synthesized and was expressed in Escherichia coli. The authenticity of this in vitro expressed peptide was confirmed by N-terminal peptide sequencing. Two groups of bioassays, artificial diet incorporation assay and contact insecticidal effect assay, were carried out separately to verify the toxicity of this recombinant toxin. At the end of a 24 h experimental period, more than 60% of the testing diamondback moth (Plutella xylostella) larvae were killed in both groups with LC50 value of 18.4 microM and 0.70 microM respectively. Cytotoxicity assay using cultured Sf9 insect cells and MCF-7 human cells demonstrated that the toxin AaIT had specific toxicity against insect cells but not human cells. Only 0.13 microM recombinant toxin was needed to kill 50% of cultured insect cells while as much as 1.3 microM toxin had absolutely no effect on human cells. Insect cells produced obvious intrusions from their plasma membrane before broken up. We infer that toxin AaIT bind to a putative sodium channel in these insect cells and open the channel persistently, which would result in Na+ influx and finally cause destruction of insect cells.展开更多
To investigate whether the expression of exogenous heme oxygenase-1 (HO-1) gene within vascular smooth muscle cells (VSMC) could protect the cells from free radical attack and inhibit cell proliferation, we establishe...To investigate whether the expression of exogenous heme oxygenase-1 (HO-1) gene within vascular smooth muscle cells (VSMC) could protect the cells from free radical attack and inhibit cell proliferation, we established an in vitro transfection of human HO-1 gene into rat VSMC mediated by a retroviral vector. The results showed that the profound expression of HO-1 protein as well as HO activity was 1.8- and 2.0-fold increased respectively in the transfected cells compared to the non-transfected ones. The treatment of VSMC with different concentrations of H2O2 led to the remarkable cell damage as indicated by survival rate and LDH leakage. However, the resistance of the HO-1 transfected VSMC against H2O2 was significantly raised. This protective effect was dramatically diminished when the transfected VSMC were pretreated with ZnPP-IX, a specific inhibitor of HO, for 24 h. In addition, we found that the growth potential of the transfected cells was significantly inhibited directly by increased activity of HO-1, and this effect might be related to decreased phosphorylation of MAPK. These results suggest that the overexpression of introduced hHO-1 is potentially able to reduce the risk factors of atherosclerosis, partially due to its cellular protection against oxidative injury and to its inhibitory effect on cellular proliferation.展开更多
在缜密论述了人地关系中人性时空场基本概念和特征的基础上,从人性时空场意识流与人地关系的相互作用的角度认知了人性时空场的科学哲学内涵。最后分析了人性时空场意识流的随机变化特点之表达。提出:随着行为地理学研究深入,人性时空...在缜密论述了人地关系中人性时空场基本概念和特征的基础上,从人性时空场意识流与人地关系的相互作用的角度认知了人性时空场的科学哲学内涵。最后分析了人性时空场意识流的随机变化特点之表达。提出:随着行为地理学研究深入,人性时空场意识流将成为它新的研究对象;与此同时,本文首次导出潜意识地理学(Potential Sense Geography)的学科概念,认为潜意识地理学会弥补行为地理学的不足,它将发挥人文关怀的当代学科优势,继而为人性的完善和人的可持续发展及人地关系的根本和谐作出贡献。展开更多
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 x 10(-9)M (Bmax=12810 sites per cell) and 8.931 x 10(-8)M (Bmax=119700 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.
基金theMajorStateBasicResearchDevelopmentProgramofChina (No G19990 5 42 0 3)
文摘OBJECTIVE: To investigate the expression of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) and the effect of lipopolysaccharide (LPS) on their expression in cultured endothelial cells. METHODS: Total RNA was extracted from ECV304 cells and isolated human umbilical vein endothelial cells (HUVECs) exposed to LPS, respectively. The quantification of TLR2 and TLR4 mRNA in HUVECs and EVC304 cells was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: ECV304 cells and HUVECs were able to express TLR2 and TLR4 mRNA, but the expression levels of TLR4 appeared to be stronger than those of TLR2. LPS could upregulate the expression levels of TLR4 obviously, whereas it had no effect on the expression level of TLR2. CONCLUSIONS: Our data indicate that TLR4 may be the LPS signal transducer in endothelial cells and plays important roles in the cell activation of LPS. The ECV304 cell line is a better experimental model than isolated HUVECs in the research of endothelial cells.
基金This work was supported by a grant from 863High Technology Program,Chinese Ministry of Sci-ence and Technology
文摘The nucleotide sequence deduced from the amino acid sequence of the scorpion insectotoxin AaIT was chemically synthesized and was expressed in Escherichia coli. The authenticity of this in vitro expressed peptide was confirmed by N-terminal peptide sequencing. Two groups of bioassays, artificial diet incorporation assay and contact insecticidal effect assay, were carried out separately to verify the toxicity of this recombinant toxin. At the end of a 24 h experimental period, more than 60% of the testing diamondback moth (Plutella xylostella) larvae were killed in both groups with LC50 value of 18.4 microM and 0.70 microM respectively. Cytotoxicity assay using cultured Sf9 insect cells and MCF-7 human cells demonstrated that the toxin AaIT had specific toxicity against insect cells but not human cells. Only 0.13 microM recombinant toxin was needed to kill 50% of cultured insect cells while as much as 1.3 microM toxin had absolutely no effect on human cells. Insect cells produced obvious intrusions from their plasma membrane before broken up. We infer that toxin AaIT bind to a putative sodium channel in these insect cells and open the channel persistently, which would result in Na+ influx and finally cause destruction of insect cells.
基金This work was kindly supported by Na-tional Natural Science Foundation of China(No.39670308)
文摘To investigate whether the expression of exogenous heme oxygenase-1 (HO-1) gene within vascular smooth muscle cells (VSMC) could protect the cells from free radical attack and inhibit cell proliferation, we established an in vitro transfection of human HO-1 gene into rat VSMC mediated by a retroviral vector. The results showed that the profound expression of HO-1 protein as well as HO activity was 1.8- and 2.0-fold increased respectively in the transfected cells compared to the non-transfected ones. The treatment of VSMC with different concentrations of H2O2 led to the remarkable cell damage as indicated by survival rate and LDH leakage. However, the resistance of the HO-1 transfected VSMC against H2O2 was significantly raised. This protective effect was dramatically diminished when the transfected VSMC were pretreated with ZnPP-IX, a specific inhibitor of HO, for 24 h. In addition, we found that the growth potential of the transfected cells was significantly inhibited directly by increased activity of HO-1, and this effect might be related to decreased phosphorylation of MAPK. These results suggest that the overexpression of introduced hHO-1 is potentially able to reduce the risk factors of atherosclerosis, partially due to its cellular protection against oxidative injury and to its inhibitory effect on cellular proliferation.
文摘在缜密论述了人地关系中人性时空场基本概念和特征的基础上,从人性时空场意识流与人地关系的相互作用的角度认知了人性时空场的科学哲学内涵。最后分析了人性时空场意识流的随机变化特点之表达。提出:随着行为地理学研究深入,人性时空场意识流将成为它新的研究对象;与此同时,本文首次导出潜意识地理学(Potential Sense Geography)的学科概念,认为潜意识地理学会弥补行为地理学的不足,它将发挥人文关怀的当代学科优势,继而为人性的完善和人的可持续发展及人地关系的根本和谐作出贡献。
