AIM:To investigate whether human acyl-CoA synthetase 5(ACSL5) is sensitive to the ACSL inhibitor triacsin C.METHODS:The ACSL isoforms ACSL1 and ACSL5 from rat as well as human ACSL5 were cloned and recombinantly expre...AIM:To investigate whether human acyl-CoA synthetase 5(ACSL5) is sensitive to the ACSL inhibitor triacsin C.METHODS:The ACSL isoforms ACSL1 and ACSL5 from rat as well as human ACSL5 were cloned and recombinantly expressed as 6xHis-tagged enzymes.Ni 2+-affinity purified recombinant enzymes were assayed at pH 7.5 or pH 9.5 in the presence or absence of triacsin C.In addition,ACSL5 transfected CaCo2 cells and intestinal human mucosa were monitored.ACSL5 expression in cellular systems was verified using Western blot and immunofluorescence.The ACSL assay mix included TrisHCl(pH 7.4),ATP,CoA,EDTA,DTT,MgCl 2,[9,103 H] palmitic acid,and triton X-100.The 200 μL reaction was initiated with the addition of solubilized,purified recombinant proteins or cellular lysates.Reactions were terminated after 10,30 or 60 min of incubation with Doles medium.RESULTS:Expression of soluble recombinant ACSL proteins was found after incubation with isopropyl betaD-1-thiogalactopyranoside and after ultracentrifugation these were further purified to near homogeneity with Ni 2+-affinity chromatography.Triacsin C selectively and strongly inhibited recombinant human ACSL5 protein at pH 7.5 and pH 9.5,as well as recombinant rat ACSL1(sensitive control),but not recombinant rat ACSL5(insensitive control).The IC50 for human ACSL5 was about 10 μmol/L.The inhibitory triacsin C effect was similar for different incubation times(10,30 and 60 min) and was not modified by the N-or C-terminal location of the 6xHis-tag.In order to evaluate ACSL5 sensitivity to triacsin C in a cellular environment,stable human ACSL5 CaCo2 transfectants and mechanically dissected normal human intestinal mucosa with high physiological expression of ACSL5 were analyzed.In both models,ACSL5 peak activity was found at pH 7.5 and pH 9.5,corresponding to the properties of recombinant human ACSL5 protein.In the presence of triacsin C(25 μmol/L),total ACSL activity was dramatically diminished in human ACSL5 transfectants as well as in ACSL5-rich human intestinal mucosa.CONCLUSION:The data strongly indicate that human ACSL5 is sensitive to triacsin C and does not compensate for other triacsin C-sensitive ACSL isoforms.展开更多
The interferon-inducible double-stranded RNA-dependent protein kinase PKR has been suggested to function as a turnour suppressor gene product.Catalytically inactive mutants of PKR give rise to a tumourigenic phenotype...The interferon-inducible double-stranded RNA-dependent protein kinase PKR has been suggested to function as a turnour suppressor gene product.Catalytically inactive mutants of PKR give rise to a tumourigenic phenotype when overexpressed in NIH-3T3 fibroblasts and this has been attributed to a dominant negative effect on only inhibits the protein kinase activity of wild-type PKR but is also inhibitory towards another dotlblestranded RNA-dependent enzyme,the 40kDa form of 2'5'oligoadenylate synthetase. Inhibition of both wile-type PKR or 2'5' oligoadenylate synthetase is reversed by adding higher concentrations of double-stranded RNA. These results suggest competition between PKR K296R and wild-type PKR or 2'5' oligoadenylate synthetase for limiting amounts of dublestranded RNA. Moreover,the data imply that the tumourigenic effect of this PKR mutant could be due to inhibition of additional pathways requiring low levels of double-strandeed RNA for activation and cannot be unambiguously attributed to inhibition of endogenous PKR itself.展开更多
AIM:To examine whether 2'-5'oligoadenylate synthetase (OAS) gene promoter can be specifically activated by hepatitis C virus (HCV)-core protein.METHODS: Human embryo hepatic cell line L02 wa transfected with p...AIM:To examine whether 2'-5'oligoadenylate synthetase (OAS) gene promoter can be specifically activated by hepatitis C virus (HCV)-core protein.METHODS: Human embryo hepatic cell line L02 wa transfected with pcDNA3.1-core plasmid and selected by G418. Expression of HCV-core was detected by reverse transcription polymerase chain reaction and Western blotting. The OAS promoter sequence wa amplified from the genomic DNA and inserted into pGL3-basic vector. The resultant pGL3-OAS-Luc plasmid was transiently transfected into L02/core cell and luciferase activity was assayed. RESULTS: L02/core cell line stably expressing HCV core protein was established. The pGL3-OAS-Luc construct exhibited significant transcriptional activity in the L02/core cells but not in the L02 cells.CONCLUSION: HCV-core protein activates the OAS gene promoter specifically and effectively. Utilization of OAS gene promoter would be an ideal strategy for developing HCV-specific gene therapy.展开更多
基金Supported by Deutsche Forschungsgemeinschaft, No. GA785/6-1Deutsche Krebshilfe, No. 109313the Rotationsprogramm of the Medical Faculty RWTH Aachen University (to Kaemmerer E)
文摘AIM:To investigate whether human acyl-CoA synthetase 5(ACSL5) is sensitive to the ACSL inhibitor triacsin C.METHODS:The ACSL isoforms ACSL1 and ACSL5 from rat as well as human ACSL5 were cloned and recombinantly expressed as 6xHis-tagged enzymes.Ni 2+-affinity purified recombinant enzymes were assayed at pH 7.5 or pH 9.5 in the presence or absence of triacsin C.In addition,ACSL5 transfected CaCo2 cells and intestinal human mucosa were monitored.ACSL5 expression in cellular systems was verified using Western blot and immunofluorescence.The ACSL assay mix included TrisHCl(pH 7.4),ATP,CoA,EDTA,DTT,MgCl 2,[9,103 H] palmitic acid,and triton X-100.The 200 μL reaction was initiated with the addition of solubilized,purified recombinant proteins or cellular lysates.Reactions were terminated after 10,30 or 60 min of incubation with Doles medium.RESULTS:Expression of soluble recombinant ACSL proteins was found after incubation with isopropyl betaD-1-thiogalactopyranoside and after ultracentrifugation these were further purified to near homogeneity with Ni 2+-affinity chromatography.Triacsin C selectively and strongly inhibited recombinant human ACSL5 protein at pH 7.5 and pH 9.5,as well as recombinant rat ACSL1(sensitive control),but not recombinant rat ACSL5(insensitive control).The IC50 for human ACSL5 was about 10 μmol/L.The inhibitory triacsin C effect was similar for different incubation times(10,30 and 60 min) and was not modified by the N-or C-terminal location of the 6xHis-tag.In order to evaluate ACSL5 sensitivity to triacsin C in a cellular environment,stable human ACSL5 CaCo2 transfectants and mechanically dissected normal human intestinal mucosa with high physiological expression of ACSL5 were analyzed.In both models,ACSL5 peak activity was found at pH 7.5 and pH 9.5,corresponding to the properties of recombinant human ACSL5 protein.In the presence of triacsin C(25 μmol/L),total ACSL activity was dramatically diminished in human ACSL5 transfectants as well as in ACSL5-rich human intestinal mucosa.CONCLUSION:The data strongly indicate that human ACSL5 is sensitive to triacsin C and does not compensate for other triacsin C-sensitive ACSL isoforms.
文摘The interferon-inducible double-stranded RNA-dependent protein kinase PKR has been suggested to function as a turnour suppressor gene product.Catalytically inactive mutants of PKR give rise to a tumourigenic phenotype when overexpressed in NIH-3T3 fibroblasts and this has been attributed to a dominant negative effect on only inhibits the protein kinase activity of wild-type PKR but is also inhibitory towards another dotlblestranded RNA-dependent enzyme,the 40kDa form of 2'5'oligoadenylate synthetase. Inhibition of both wile-type PKR or 2'5' oligoadenylate synthetase is reversed by adding higher concentrations of double-stranded RNA. These results suggest competition between PKR K296R and wild-type PKR or 2'5' oligoadenylate synthetase for limiting amounts of dublestranded RNA. Moreover,the data imply that the tumourigenic effect of this PKR mutant could be due to inhibition of additional pathways requiring low levels of double-strandeed RNA for activation and cannot be unambiguously attributed to inhibition of endogenous PKR itself.
基金Supported by National Natural Science Foundation of China,No.30671846
文摘AIM:To examine whether 2'-5'oligoadenylate synthetase (OAS) gene promoter can be specifically activated by hepatitis C virus (HCV)-core protein.METHODS: Human embryo hepatic cell line L02 wa transfected with pcDNA3.1-core plasmid and selected by G418. Expression of HCV-core was detected by reverse transcription polymerase chain reaction and Western blotting. The OAS promoter sequence wa amplified from the genomic DNA and inserted into pGL3-basic vector. The resultant pGL3-OAS-Luc plasmid was transiently transfected into L02/core cell and luciferase activity was assayed. RESULTS: L02/core cell line stably expressing HCV core protein was established. The pGL3-OAS-Luc construct exhibited significant transcriptional activity in the L02/core cells but not in the L02 cells.CONCLUSION: HCV-core protein activates the OAS gene promoter specifically and effectively. Utilization of OAS gene promoter would be an ideal strategy for developing HCV-specific gene therapy.
基金Guangxi Scientific Fund for Innovation and Condition Construction(Guike Neng 0630006-5F)Science and Tech-nology Development Fund of Guangxi Academy of Agricultural Sciences(2007024)Guike Gong 0782004 and National Science and Technology Support Program(2007BAD30B02 and 2007BAD30B03)
