目的探讨α吡喃酮类化合物Rasfonin对鸟苷酸交换因子SOS1表达的调控作用及其机制。方法(1)将MCF-7、Calu-1和UM-UC-3细胞分别分为溶剂对照组和Rasfonin组(1、5、10和15μmol·L^(-1)),处理24 h后CCK-8法检测MCF-7、Calu-1和UM-UC-3...目的探讨α吡喃酮类化合物Rasfonin对鸟苷酸交换因子SOS1表达的调控作用及其机制。方法(1)将MCF-7、Calu-1和UM-UC-3细胞分别分为溶剂对照组和Rasfonin组(1、5、10和15μmol·L^(-1)),处理24 h后CCK-8法检测MCF-7、Calu-1和UM-UC-3细胞存活率。将MCF-7、Calu-1和UM-UC-3细胞分别分为细胞对照组(培养基)、表皮生长因子组(EGF 50μg·L^(-1)处理5 min),EGF+Rasfonin组(Rasfonin分别以5和10μmol·L^(-1)预处理不同时间后,再EGF 50μg·L^(-1)处理5 min),实时荧光定量PCR和Western印迹法检测MCF-7、Calu-1和UM-UC-3细胞中SOS1 m RNA和蛋白表达水平。(2)将阴性对照(NC)质粒、KRASWT质粒和KRASG12C质粒分别与SOS1质粒共转染至293T细胞,转染后分为溶剂对照组和Rasfonin组(1、5和10μmol·L^(-1)),处理12 h后采用双荧光素酶报告基因实验检测SOS1启动子活性。将质粒KRAS^(WT)、KRAS^(G12C)、NC+SOS1、KRAS^(WT)+SOS1和KRAS^(G12C)+SOS1分别转染至293T细胞,分为EGF组和EGF+Rasfonin组(Rasfonin 10μmol·L^(-1)预处理12 h后,再EGF处理5 min),Western印迹法检测293T细胞中SOS1蛋白表达水平。结果(1)与溶剂对照组相比,Rasfonin 5、10和15μmol·L^(-1)显著抑制Calu-1和UM-UC-3细胞增殖,IC_(50)分别为8.22和4.94μmol·L^(-1),MCF-7细胞的IC50为45.15μmol·L^(-1)。Rasfonin处理3 h MCF-7细胞SOS1 m RNA水平升高;Rasfonin处理1 h Calu-1细胞SOS1 m RNA水平升高,3和6 h SOS1 m RNA水平降低;Rasfonin处理3 h UM-UC-3细胞SOS1 m RNA表达,6 h降低。与EGF组相比,EGF+Rasfonin组MCF-7细胞的SOS1蛋白表达水平无显著变化,Calu-1与UM-UC-3细胞的SOS1蛋白表达水平显著降低。(2)与溶剂对照组相比,Rasfonin对SOS1单表达组SOS1启动子活性无显著影响,但SOS1与KRAS^(WT)或KRAS^(G12C)蛋白共表达时,SOS1启动子活性被Rasfonin显著抑制。与EGF组相比,Rasfonin对SOS1单表达组及SOS1+KRAS^(WT)共表达组的SOS1蛋白表达水平无显著变化,SOS1+KRAS^(G12C)共表达组的SOS1蛋白表达水平显著降低。结论Rasfonin通过KRASG12C依赖性途径抑制SOS1表达,这可能是其抗肿瘤作用的机制之一。展开更多
目前,直流微电网在全球范围内快速发展,开展充分的稳定性分析工作是其稳定运行的前提。伴随着大量电力电子装置的接入,相较于传统电网,直流微电网系统等效惯性不足,在经历电网故障、电压暂降或恒功率负载接入接出等大扰动场景后,其状态...目前,直流微电网在全球范围内快速发展,开展充分的稳定性分析工作是其稳定运行的前提。伴随着大量电力电子装置的接入,相较于传统电网,直流微电网系统等效惯性不足,在经历电网故障、电压暂降或恒功率负载接入接出等大扰动场景后,其状态变量易发生大范围变化,暂态稳定性问题突出。Lyapunov方法是分析暂态稳定性问题的常用方法,但在直流微电网领域中缺少指导构建Lyapunov函数的通用策略,很难直接进行应用。此外,为了提高稳定性,亟待开展以提升暂态稳定性为导向的控制参数优化设计研究。针对以上问题,针对直流微电网系统,考虑DC-DC变换器控制环路,基于平方和(sum of squares,SOS)规划方法开展暂态稳定域估计与参数优化研究,首先,通过设计SOS优化问题,改进传统拓展内部算法求解并获得最大化Lyapunov函数水平集实现对系统稳定域的估计,通过与系统实际稳定域进行对比,验证了所提方法的准确性,与其他现有方法估计的稳定域相比,所提方法保守性大幅降低。随后,基于SOS规划,以拓展稳定域为目标,对电压控制环路参数进行优化。最后,硬件在环仿真实验结果表明,采用优化控制参数后,直流微电网系统稳定域得到扩展,抗扰动能力有效提升,暂态稳定性进一步增强。展开更多
The Kirsten rat sarcoma virus—son of sevenless 1(KRAS-SOS1)axis drives tumor growth preferentially in pancreatic,colon,and lung cancer.Now,KRAS G12C mutated tumors can be successfully treated with inhibitors that cov...The Kirsten rat sarcoma virus—son of sevenless 1(KRAS-SOS1)axis drives tumor growth preferentially in pancreatic,colon,and lung cancer.Now,KRAS G12C mutated tumors can be successfully treated with inhibitors that covalently block the cysteine of the switch II binding pocket of KRAS.However,the range of other KRAS mutations is not amenable to treatment and the G12C-directed agents Sotorasib and Adragrasib show a response rate of only approximately 40%,lasting for a mean period of 8 months.One approach to increase the efficacy of inhibitors is their inclusion into proteolysis-targeting chimeras(PROTACs),which degrade the proteins of interest and exhibit much higher antitumor activity through multiple cycles of activity.Accordingly,PROTACs have been developed based on KRAS-or SOS1-directed inhibitors coupled to either von Hippel-Lindau(VHL)or Cereblon(CRBN)ligands that invoke the proteasomal degradation.Several of these PROTACs show increased activity in vitro and in vivo compared to their cognate inhibitors but their toxicity in normal tissues is not clear.The CRBN PROTACs containing thalidomide derivatives cannot be tested in experimental animals.Resistance to such PROTACS arises through downregulation or inactivation of CRBN or factors of the functional VHL E3 ubiquitin ligase.Although highly active KRAS and SOS1 PROTACs have been formulated their clinical application remains difficult.展开更多
Objective:To study the influences of LncRNA H19(H19)on malignant liver tumor cells and elucidate the underlying molecular mechanisms.Methods:H19 expression in liver tumor tissues,matched normal liver tissues,human liv...Objective:To study the influences of LncRNA H19(H19)on malignant liver tumor cells and elucidate the underlying molecular mechanisms.Methods:H19 expression in liver tumor tissues,matched normal liver tissues,human liver malignant tumor cell lines and the human hepatocyte line LO2 was assessed via quantitative RT-PCR.Cell viability analysis and Matrigel invasion analysis were performed to evaluate the effects of H19 on cell proliferation and invasion.Luciferase reporter analysis was carried out to assess the interaction between miR-140-5p and SOS Ras/Rac guanine nucleotide exchange factor 1(SOS1).The influence of H19 on the Ras-MAPK signalling pathway was evaluated by detecting key protein levels via active Ras pull-down analysis and Western blot analysis.Results:H19 expression was lower in liver cancer samples than in matched normal liver tissue samples.H19 overexpression enhanced the proliferation and invasion of HepG2 and SMMC-7721 cells.H19 overexpression increased the level of activated Ras.The expression levels of phosphorylated Raf,phosphorylated ERK and phosphorylated MEK were increased by H19 overexpression.H19 knockdown had the opposite effect.Treatment with a MAPK inhibitor significantly reversed the influence of H19 overexpression on liver malignant tumor cell growth and invasion.The MAPK activator reversed the opposing effects of H19 silencing.H19 overexpression increased the protein level of SOS1,and miR-140-5p directly targeted SOS1.Conclusion:H19 can activate the Ras-MAPK signalling pathway via the miR-140-5p/SOS1 axis in malignant liver tumour cells.展开更多
Soil salinity hampers plant performance.Elevated atmospheric CO_(2)(e[CO_(2)])could alleviate the detrimental effect of salinity on plants but whether abscisic acid(ABA)is involved in this process is unclear.To addres...Soil salinity hampers plant performance.Elevated atmospheric CO_(2)(e[CO_(2)])could alleviate the detrimental effect of salinity on plants but whether abscisic acid(ABA)is involved in this process is unclear.To address this issue,three tomato(Solanum lycopersicum)genotypes with varying endogenous ABA concentrations(wild-type AC,ABA-deficient mutant flacca and ABA-overproduction line SP5)were grown in pots under ambient(400μmol·mol^(-1))or elevated(800μmol·mol^(-1))CO_(2)with or without the addition of 100 mmol·L-1sodium chloride(NaCl).The results showed that e[CO_(2)]favored ion homeostasis by decreasing root-to-shoot delivery of Na^(+),which was mainly attributed to lowered transpiration rate rather than altered xylem-sap Na^(+)concentration.In AC and SP5,the low transpiration rate of e[CO_(2)]-plants under salinity was accompanied by enhanced endogenous ABA levels,which might play a role in upregulating the abundance of specific transcripts related to Na^(+)homeostasis(i.e.,SALT OVERLY SENSITIVE)under salt stress.In flacca,e[CO_(2)]-induced Na^(+)homeostasis was abolished,which could be ascribed to the low and unaltered ABA levels,albeit the ethylene biosynthesis was enhanced in flacca under salt stress,indicating an antagonistic relationship between ABA and ethylene.Furthermore,e[CO_(2)]inhibited ethylene biosynthesis under salt stress in all three genotypes.The results enrich our comprehension of the fundamental processes of e[CO_(2)]-conferred salt tolerance in tomato.展开更多
文摘目的探讨α吡喃酮类化合物Rasfonin对鸟苷酸交换因子SOS1表达的调控作用及其机制。方法(1)将MCF-7、Calu-1和UM-UC-3细胞分别分为溶剂对照组和Rasfonin组(1、5、10和15μmol·L^(-1)),处理24 h后CCK-8法检测MCF-7、Calu-1和UM-UC-3细胞存活率。将MCF-7、Calu-1和UM-UC-3细胞分别分为细胞对照组(培养基)、表皮生长因子组(EGF 50μg·L^(-1)处理5 min),EGF+Rasfonin组(Rasfonin分别以5和10μmol·L^(-1)预处理不同时间后,再EGF 50μg·L^(-1)处理5 min),实时荧光定量PCR和Western印迹法检测MCF-7、Calu-1和UM-UC-3细胞中SOS1 m RNA和蛋白表达水平。(2)将阴性对照(NC)质粒、KRASWT质粒和KRASG12C质粒分别与SOS1质粒共转染至293T细胞,转染后分为溶剂对照组和Rasfonin组(1、5和10μmol·L^(-1)),处理12 h后采用双荧光素酶报告基因实验检测SOS1启动子活性。将质粒KRAS^(WT)、KRAS^(G12C)、NC+SOS1、KRAS^(WT)+SOS1和KRAS^(G12C)+SOS1分别转染至293T细胞,分为EGF组和EGF+Rasfonin组(Rasfonin 10μmol·L^(-1)预处理12 h后,再EGF处理5 min),Western印迹法检测293T细胞中SOS1蛋白表达水平。结果(1)与溶剂对照组相比,Rasfonin 5、10和15μmol·L^(-1)显著抑制Calu-1和UM-UC-3细胞增殖,IC_(50)分别为8.22和4.94μmol·L^(-1),MCF-7细胞的IC50为45.15μmol·L^(-1)。Rasfonin处理3 h MCF-7细胞SOS1 m RNA水平升高;Rasfonin处理1 h Calu-1细胞SOS1 m RNA水平升高,3和6 h SOS1 m RNA水平降低;Rasfonin处理3 h UM-UC-3细胞SOS1 m RNA表达,6 h降低。与EGF组相比,EGF+Rasfonin组MCF-7细胞的SOS1蛋白表达水平无显著变化,Calu-1与UM-UC-3细胞的SOS1蛋白表达水平显著降低。(2)与溶剂对照组相比,Rasfonin对SOS1单表达组SOS1启动子活性无显著影响,但SOS1与KRAS^(WT)或KRAS^(G12C)蛋白共表达时,SOS1启动子活性被Rasfonin显著抑制。与EGF组相比,Rasfonin对SOS1单表达组及SOS1+KRAS^(WT)共表达组的SOS1蛋白表达水平无显著变化,SOS1+KRAS^(G12C)共表达组的SOS1蛋白表达水平显著降低。结论Rasfonin通过KRASG12C依赖性途径抑制SOS1表达,这可能是其抗肿瘤作用的机制之一。
文摘目前,直流微电网在全球范围内快速发展,开展充分的稳定性分析工作是其稳定运行的前提。伴随着大量电力电子装置的接入,相较于传统电网,直流微电网系统等效惯性不足,在经历电网故障、电压暂降或恒功率负载接入接出等大扰动场景后,其状态变量易发生大范围变化,暂态稳定性问题突出。Lyapunov方法是分析暂态稳定性问题的常用方法,但在直流微电网领域中缺少指导构建Lyapunov函数的通用策略,很难直接进行应用。此外,为了提高稳定性,亟待开展以提升暂态稳定性为导向的控制参数优化设计研究。针对以上问题,针对直流微电网系统,考虑DC-DC变换器控制环路,基于平方和(sum of squares,SOS)规划方法开展暂态稳定域估计与参数优化研究,首先,通过设计SOS优化问题,改进传统拓展内部算法求解并获得最大化Lyapunov函数水平集实现对系统稳定域的估计,通过与系统实际稳定域进行对比,验证了所提方法的准确性,与其他现有方法估计的稳定域相比,所提方法保守性大幅降低。随后,基于SOS规划,以拓展稳定域为目标,对电压控制环路参数进行优化。最后,硬件在环仿真实验结果表明,采用优化控制参数后,直流微电网系统稳定域得到扩展,抗扰动能力有效提升,暂态稳定性进一步增强。
文摘The Kirsten rat sarcoma virus—son of sevenless 1(KRAS-SOS1)axis drives tumor growth preferentially in pancreatic,colon,and lung cancer.Now,KRAS G12C mutated tumors can be successfully treated with inhibitors that covalently block the cysteine of the switch II binding pocket of KRAS.However,the range of other KRAS mutations is not amenable to treatment and the G12C-directed agents Sotorasib and Adragrasib show a response rate of only approximately 40%,lasting for a mean period of 8 months.One approach to increase the efficacy of inhibitors is their inclusion into proteolysis-targeting chimeras(PROTACs),which degrade the proteins of interest and exhibit much higher antitumor activity through multiple cycles of activity.Accordingly,PROTACs have been developed based on KRAS-or SOS1-directed inhibitors coupled to either von Hippel-Lindau(VHL)or Cereblon(CRBN)ligands that invoke the proteasomal degradation.Several of these PROTACs show increased activity in vitro and in vivo compared to their cognate inhibitors but their toxicity in normal tissues is not clear.The CRBN PROTACs containing thalidomide derivatives cannot be tested in experimental animals.Resistance to such PROTACS arises through downregulation or inactivation of CRBN or factors of the functional VHL E3 ubiquitin ligase.Although highly active KRAS and SOS1 PROTACs have been formulated their clinical application remains difficult.
基金supported by grants from Guangxi Nanning Qingxiu District Key Research and Development Program of Science and Technology Plan(No.2020050)Guangxi Medical and Health Appropriate Technology Development,Promotion and Application Project(No.S2021097)+1 种基金Guangxi Key Research and Development Program(No.AB22080064)Guangxi Natural Science Foundation(No.2017GXNSFAA198126,No.2022GXNSFAA035509).
文摘Objective:To study the influences of LncRNA H19(H19)on malignant liver tumor cells and elucidate the underlying molecular mechanisms.Methods:H19 expression in liver tumor tissues,matched normal liver tissues,human liver malignant tumor cell lines and the human hepatocyte line LO2 was assessed via quantitative RT-PCR.Cell viability analysis and Matrigel invasion analysis were performed to evaluate the effects of H19 on cell proliferation and invasion.Luciferase reporter analysis was carried out to assess the interaction between miR-140-5p and SOS Ras/Rac guanine nucleotide exchange factor 1(SOS1).The influence of H19 on the Ras-MAPK signalling pathway was evaluated by detecting key protein levels via active Ras pull-down analysis and Western blot analysis.Results:H19 expression was lower in liver cancer samples than in matched normal liver tissue samples.H19 overexpression enhanced the proliferation and invasion of HepG2 and SMMC-7721 cells.H19 overexpression increased the level of activated Ras.The expression levels of phosphorylated Raf,phosphorylated ERK and phosphorylated MEK were increased by H19 overexpression.H19 knockdown had the opposite effect.Treatment with a MAPK inhibitor significantly reversed the influence of H19 overexpression on liver malignant tumor cell growth and invasion.The MAPK activator reversed the opposing effects of H19 silencing.H19 overexpression increased the protein level of SOS1,and miR-140-5p directly targeted SOS1.Conclusion:H19 can activate the Ras-MAPK signalling pathway via the miR-140-5p/SOS1 axis in malignant liver tumour cells.
基金supported by the Chinese Scholarship Council(CSC).
文摘Soil salinity hampers plant performance.Elevated atmospheric CO_(2)(e[CO_(2)])could alleviate the detrimental effect of salinity on plants but whether abscisic acid(ABA)is involved in this process is unclear.To address this issue,three tomato(Solanum lycopersicum)genotypes with varying endogenous ABA concentrations(wild-type AC,ABA-deficient mutant flacca and ABA-overproduction line SP5)were grown in pots under ambient(400μmol·mol^(-1))or elevated(800μmol·mol^(-1))CO_(2)with or without the addition of 100 mmol·L-1sodium chloride(NaCl).The results showed that e[CO_(2)]favored ion homeostasis by decreasing root-to-shoot delivery of Na^(+),which was mainly attributed to lowered transpiration rate rather than altered xylem-sap Na^(+)concentration.In AC and SP5,the low transpiration rate of e[CO_(2)]-plants under salinity was accompanied by enhanced endogenous ABA levels,which might play a role in upregulating the abundance of specific transcripts related to Na^(+)homeostasis(i.e.,SALT OVERLY SENSITIVE)under salt stress.In flacca,e[CO_(2)]-induced Na^(+)homeostasis was abolished,which could be ascribed to the low and unaltered ABA levels,albeit the ethylene biosynthesis was enhanced in flacca under salt stress,indicating an antagonistic relationship between ABA and ethylene.Furthermore,e[CO_(2)]inhibited ethylene biosynthesis under salt stress in all three genotypes.The results enrich our comprehension of the fundamental processes of e[CO_(2)]-conferred salt tolerance in tomato.
