Cyclin-dependent kinase 1 （Cdkl）/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 （also known...Cyclin-dependent kinase 1 （Cdkl）/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 （also known as Cdk5rap3 and LZAP） potentiates DNA damage-induced cell death by modulating the G2/M checkpoint. More recently, Wang et al. （2007） found that C53/LZAP may function as a tumor suppressor by way of inhibiting NF-kB signaling. We re- port here the identification of C53 protein as a novel regulator of Cdkl activation. We found that knockdown of C53 protein causes delayed Cdkl activation and mitotic entry. During DNA damage response, activation of checkpoint kinase 1 and 2 （Chkl and Chk2） is partially inhibited by C53 overexpression. Intriguingly, we found that C53 inter- acts with Chkl and antagonizes its function. Moreover, a portion of C53 protein is localized at the centrosome, and centrosome-targeting C53 potently promotes local Cdkl activation. Taken together, our results strongly suggest that C53 is a novel negative regulator of checkpoint response. By counteracting Chkl, C53 promotes Cdkl activation and mitotic entry in both unperturbed cell-cycle progression and DNA damage response.展开更多
目的研究肝癌细胞系HepG2中乙型肝炎表面抗原大蛋白（hepatitis B virus large surface protein，LHBs）与C53蛋白是否存在共定位，查明LHBs与C53蛋白的结合区域。方法分别构建pEGFP-C1·LHBs和pDsRedl-N1·C53质粒，共同转染...目的研究肝癌细胞系HepG2中乙型肝炎表面抗原大蛋白（hepatitis B virus large surface protein，LHBs）与C53蛋白是否存在共定位，查明LHBs与C53蛋白的结合区域。方法分别构建pEGFP-C1·LHBs和pDsRedl-N1·C53质粒，共同转染肝癌细胞系HepG2，激光共聚焦观察它们在细胞内的共定位。构建质粒pCDNA-3．1（-）myc／his-LHBs和pCMV-5a-C53，并将C53基因截短构建质粒pCMV-5a-C53N、pCMV-5a-C1、pCMV-5a-C2和pCMV．5a-C3，将pCDNA-3．1（-）myc／his．LHBs和pc-MV-5a-C53及各截短质粒共转染HepG2细胞，免疫共沉淀方法验证LHBs结合的C53区域。结果成功构建pEGFP-C1-LHBs、pDsRedl-N1-C53、pCDNA-3．1（-）myc／his-LHBs、pCMV-5a-C53、pCMV-5a-C53N、pCMV-5a-C1、pCMV-5a-C2和pCMV-5a-C3质粒；用激光共聚焦的方法证实了LHBs与C53在HepG2细胞内存在共定位；免疫共沉淀方法证实了在HepG2细胞内LHBs与C53的结合区域为其c1区。结论LHBs与C53在肝癌细胞系HepG2内存在明确的相互作用，但仍需做进一步的功能研究。展开更多
目的明确肝癌细胞系HepG2中前S2区突变乙型肝炎表面抗原大蛋白（hepatitis Bvirus large surface protein，LHBs）与C53蛋白相互作用对细胞生物学功能的影响。方法分别构建pc—MV-5a·pres2LHBs和pCDNA-4-C53质粒，共同转染肝癌细胞...目的明确肝癌细胞系HepG2中前S2区突变乙型肝炎表面抗原大蛋白（hepatitis Bvirus large surface protein，LHBs）与C53蛋白相互作用对细胞生物学功能的影响。方法分别构建pc—MV-5a·pres2LHBs和pCDNA-4-C53质粒，共同转染肝癌细胞系HepG2后，分别检测其相互作用对Chkl活性的影响；BrdU法细胞增殖检测明确其对细胞有丝分裂及增殖的影响。结果成功构建pc—MV-5a—pres2LHBs和pCDNA-4-C53质粒；其在细胞内的相互作用增加细胞Cdkl活性并促进细胞的增殖和有丝分裂过程。结论肝癌细胞系HepG2内pres2LHBs及C53的相互作用对细胞生物学功能存在影响，提示可能与HBV后肝癌的发病机制相关。展开更多
目的 研究肝癌细胞系HepG2中乙型肝炎表面抗原大蛋白（hepatitis B virus large surface protein,LHBs）与C53蛋白结合后对细胞生物学功能的影响.方法 分别构建pCDNA-LHBs、pC-MV-5a-C53和pAdTrack-CMV-C53的shRNA干扰质粒,转染肝癌细胞...目的 研究肝癌细胞系HepG2中乙型肝炎表面抗原大蛋白（hepatitis B virus large surface protein,LHBs）与C53蛋白结合后对细胞生物学功能的影响.方法 分别构建pCDNA-LHBs、pC-MV-5a-C53和pAdTrack-CMV-C53的shRNA干扰质粒,转染肝癌细胞系HepG2.采用BrdU标记试验、3H掺入试验和WB实验研究对细胞生物学功能的影响.结果 成功构建pCDNA-LHBs、pCMV-5a-C53和pAdTrack-CMV-C53质粒;BrdU和H3标记试验证实,在HepG2细胞内LHBs通过与C53蛋白结合促进细胞进入有丝分裂期,进而促进细胞增殖,该作用与Cdk1相关.结论 肝癌细胞系HepG2中LHBs通过与C53蛋白结合促进细胞进入有丝分裂期,进而促进细胞增殖,该作用与Cdk1相关.展开更多
Telomerase is a large ribonucleoprotein complex that contains a catalytic telomerase reverse transcriptase(TERT)and an RNA template.Telomerase activity is tightly controlled by TERT expression,which is regulated at bo...Telomerase is a large ribonucleoprotein complex that contains a catalytic telomerase reverse transcriptase(TERT)and an RNA template.Telomerase activity is tightly controlled by TERT expression,which is regulated at both the transcriptional and post-translational levels.However,the detailed molecular mechanisms of telomerase regulation and function are not fully understood.To identify cofactors that contribute to telomerase regulation,we employed a yeast two-hybrid system to screen for hTERT-interacting proteins,using the hTERT T-motif as bait.We identify C53 as a novel hTERT interaction partner.We show that C53 interacts with hTERT both in vivo and in vitro.C53 depletion increases telomerase activity,and C53 overexpression inhibits telomerase activity in MCF7 cells.In addition,the C53 leucine zipper domain(amino acids 301–400)is required for interaction with hTERT.Deleting the leucine zipper domain eliminates C53 interaction with hTERT and abrogates its inhibitory effect on telomerase activity.Taken together,our results demonstrate that C53 is a novel hTERT-associated protein that negatively regulates telomerase activity.展开更多
Quantitative study of the impact of Shanghai World Expo on green GDP （GGDP） is significant for deploying sustainable development policy in China. The formula of GGDP is： GGDP = GDP--the loss of natural resources en...Quantitative study of the impact of Shanghai World Expo on green GDP （GGDP） is significant for deploying sustainable development policy in China. The formula of GGDP is： GGDP = GDP--the loss of natural resources environment relegation cost ＋ comprehensive utilized value of waste. Based on this, the study employed vector autoregressive （VAR） model to predict the value of GGDP and other economic variables on condition that there was no Shanghai World Expo. Then Influence of Expo is defined as the rate of increase of GGDP. The result demonstrated that Shanghai World Expo had accelerated the growth rate of GGDP vastly with the elimination of effect of Beijing Olympics. Additionally, the quantitative analysis between GGDP and other economic variables suggested GGDP would replace GDP to evaluate the development of economy. Finally, the paper proposed that incidents like World Expo can enhance the level of influence for a country and that post-impact of Shanghai Expo should continue to be used to promote GGDP and that GGDP should serve as one of the indicators in assessment of political achievement.展开更多
文摘Cyclin-dependent kinase 1 （Cdkl）/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 （also known as Cdk5rap3 and LZAP） potentiates DNA damage-induced cell death by modulating the G2/M checkpoint. More recently, Wang et al. （2007） found that C53/LZAP may function as a tumor suppressor by way of inhibiting NF-kB signaling. We re- port here the identification of C53 protein as a novel regulator of Cdkl activation. We found that knockdown of C53 protein causes delayed Cdkl activation and mitotic entry. During DNA damage response, activation of checkpoint kinase 1 and 2 （Chkl and Chk2） is partially inhibited by C53 overexpression. Intriguingly, we found that C53 inter- acts with Chkl and antagonizes its function. Moreover, a portion of C53 protein is localized at the centrosome, and centrosome-targeting C53 potently promotes local Cdkl activation. Taken together, our results strongly suggest that C53 is a novel negative regulator of checkpoint response. By counteracting Chkl, C53 promotes Cdkl activation and mitotic entry in both unperturbed cell-cycle progression and DNA damage response.
文摘目的研究肝癌细胞系HepG2中乙型肝炎表面抗原大蛋白（hepatitis B virus large surface protein，LHBs）与C53蛋白是否存在共定位，查明LHBs与C53蛋白的结合区域。方法分别构建pEGFP-C1·LHBs和pDsRedl-N1·C53质粒，共同转染肝癌细胞系HepG2，激光共聚焦观察它们在细胞内的共定位。构建质粒pCDNA-3．1（-）myc／his-LHBs和pCMV-5a-C53，并将C53基因截短构建质粒pCMV-5a-C53N、pCMV-5a-C1、pCMV-5a-C2和pCMV．5a-C3，将pCDNA-3．1（-）myc／his．LHBs和pc-MV-5a-C53及各截短质粒共转染HepG2细胞，免疫共沉淀方法验证LHBs结合的C53区域。结果成功构建pEGFP-C1-LHBs、pDsRedl-N1-C53、pCDNA-3．1（-）myc／his-LHBs、pCMV-5a-C53、pCMV-5a-C53N、pCMV-5a-C1、pCMV-5a-C2和pCMV-5a-C3质粒；用激光共聚焦的方法证实了LHBs与C53在HepG2细胞内存在共定位；免疫共沉淀方法证实了在HepG2细胞内LHBs与C53的结合区域为其c1区。结论LHBs与C53在肝癌细胞系HepG2内存在明确的相互作用，但仍需做进一步的功能研究。
文摘目的明确肝癌细胞系HepG2中前S2区突变乙型肝炎表面抗原大蛋白（hepatitis Bvirus large surface protein，LHBs）与C53蛋白相互作用对细胞生物学功能的影响。方法分别构建pc—MV-5a·pres2LHBs和pCDNA-4-C53质粒，共同转染肝癌细胞系HepG2后，分别检测其相互作用对Chkl活性的影响；BrdU法细胞增殖检测明确其对细胞有丝分裂及增殖的影响。结果成功构建pc—MV-5a—pres2LHBs和pCDNA-4-C53质粒；其在细胞内的相互作用增加细胞Cdkl活性并促进细胞的增殖和有丝分裂过程。结论肝癌细胞系HepG2内pres2LHBs及C53的相互作用对细胞生物学功能存在影响，提示可能与HBV后肝癌的发病机制相关。
文摘目的 研究肝癌细胞系HepG2中乙型肝炎表面抗原大蛋白（hepatitis B virus large surface protein,LHBs）与C53蛋白结合后对细胞生物学功能的影响.方法 分别构建pCDNA-LHBs、pC-MV-5a-C53和pAdTrack-CMV-C53的shRNA干扰质粒,转染肝癌细胞系HepG2.采用BrdU标记试验、3H掺入试验和WB实验研究对细胞生物学功能的影响.结果 成功构建pCDNA-LHBs、pCMV-5a-C53和pAdTrack-CMV-C53质粒;BrdU和H3标记试验证实,在HepG2细胞内LHBs通过与C53蛋白结合促进细胞进入有丝分裂期,进而促进细胞增殖,该作用与Cdk1相关.结论 肝癌细胞系HepG2中LHBs通过与C53蛋白结合促进细胞进入有丝分裂期,进而促进细胞增殖,该作用与Cdk1相关.
基金supported by the National Basic Research Program of China(2012CB911203)the National Natural Science Foundation of China(31371398,31071200 and 31171320)
文摘Telomerase is a large ribonucleoprotein complex that contains a catalytic telomerase reverse transcriptase(TERT)and an RNA template.Telomerase activity is tightly controlled by TERT expression,which is regulated at both the transcriptional and post-translational levels.However,the detailed molecular mechanisms of telomerase regulation and function are not fully understood.To identify cofactors that contribute to telomerase regulation,we employed a yeast two-hybrid system to screen for hTERT-interacting proteins,using the hTERT T-motif as bait.We identify C53 as a novel hTERT interaction partner.We show that C53 interacts with hTERT both in vivo and in vitro.C53 depletion increases telomerase activity,and C53 overexpression inhibits telomerase activity in MCF7 cells.In addition,the C53 leucine zipper domain(amino acids 301–400)is required for interaction with hTERT.Deleting the leucine zipper domain eliminates C53 interaction with hTERT and abrogates its inhibitory effect on telomerase activity.Taken together,our results demonstrate that C53 is a novel hTERT-associated protein that negatively regulates telomerase activity.
文摘Quantitative study of the impact of Shanghai World Expo on green GDP （GGDP） is significant for deploying sustainable development policy in China. The formula of GGDP is： GGDP = GDP--the loss of natural resources environment relegation cost ＋ comprehensive utilized value of waste. Based on this, the study employed vector autoregressive （VAR） model to predict the value of GGDP and other economic variables on condition that there was no Shanghai World Expo. Then Influence of Expo is defined as the rate of increase of GGDP. The result demonstrated that Shanghai World Expo had accelerated the growth rate of GGDP vastly with the elimination of effect of Beijing Olympics. Additionally, the quantitative analysis between GGDP and other economic variables suggested GGDP would replace GDP to evaluate the development of economy. Finally, the paper proposed that incidents like World Expo can enhance the level of influence for a country and that post-impact of Shanghai Expo should continue to be used to promote GGDP and that GGDP should serve as one of the indicators in assessment of political achievement.
