AIM To investigate the role of nuclear division cycle(NDC)80in human hepatocellular carcinogenesis.METHODS NDC80 gene expression was analyzed by real-time reverse transcription polymerase chain reaction in 47paired he...AIM To investigate the role of nuclear division cycle(NDC)80in human hepatocellular carcinogenesis.METHODS NDC80 gene expression was analyzed by real-time reverse transcription polymerase chain reaction in 47paired hepatocellular carcinoma(HCC)and adjacent tissues.The HCC cell line SMMC-7721 was transfected with lentivirus to silence endogenous NDC80 gene expression,which was confirmed by real-time polymerase chain reaction and western blotting.The effects of NDC80silencing on SMMC-7721 cell proliferation were evaluated by Cellomics Array Scan VTI imaging.Cell cycle analysis and apoptosis were detected with flow cytometry.Colony formation was assessed by fluorescence microscopy.RESULTS NDC80 expression levels in HCC tissues were significantly higher than those in the adjacent tissues.Functional studies demonstrated that NDC80 silencing significantly reduced SMMC-7721 cell proliferation and colony formation.Knockdown of NDC80 resulted in increased apoptosis and cell cycle arrest at S-phase.NDC80 contributed to HCC progression by reducing apoptosis and overcoming cell cycle arrest. CONCLUSION Elevated expression of NDC80 may play a role in promoting the development of HCC.展开更多
Error-free mitosis depends on accurate chromosome attachment to spindle microtubules,which is monitored by the spindle assembly checkpoint(SAC)signaling.As an upstream factor of SAC,the precise and dynamic kinetochore...Error-free mitosis depends on accurate chromosome attachment to spindle microtubules,which is monitored by the spindle assembly checkpoint(SAC)signaling.As an upstream factor of SAC,the precise and dynamic kinetochore localization of Mps1 kinase is critical for initiating and silencing SAC signaling.However,the underlying molecular mechanism remains elusive.Here,we demonstrated that the multisite interactions between Mps1 and Ndc80 complex(Ndc80C)govern Mps1 kinetochore targeting.Importantly,we identified direct interaction between Mps1 tetratricopeptide repeat domain and Ndc80C.We further identified that Mps1 C-terminal fragment,which contains the protein kinase domain and C-tail,enhances Mps1 kinetochore localization.Mechanistically,Mps1 C-terminal fragment mediates its dimerization.Perturbation of C-tail attenuates the kinetochore targeting and activity of Mps1,leading to aberrant mitosis due to compromised SAC function.Taken together,our study highlights the importance of Mps1 dimerization and multisite interactions with Ndc80C in enabling responsive SAC signaling.展开更多
In eukaryote cells,cargos are often transported cooperatively by kinesin motors and nonmotor microtubule-associated proteins(MAPs).The prior in vitro experimental data showed that the velocity of the cargo transported...In eukaryote cells,cargos are often transported cooperatively by kinesin motors and nonmotor microtubule-associated proteins(MAPs).The prior in vitro experimental data showed that the velocity of the cargo transported by kinesin motors and Ndc80(a member of MAP)proteins of truncated coiled-coil stalks decreases sensitively with the increase of the ratio of Ndc80 to motor number.However,the underlying mechanism of Ndc80 affecting sensitively the cooperative cargo transport by kinesin motors is unclear.To understand the mechanism,here we study numerically the cooperative cargo transport by kinesin motors and Ndc80 proteins.Our results showed that for the case of the motors and Ndc80 proteins with truncated short stalks,as used in the experiments,the calculated results reproduce quantitatively the prior experimental data.The mechanism of the cargo velocity decreasing sensitively with the ratio of Ndc80 to motor number is revealed.By contrast,for the case of the motors and Ndc80 proteins with full-length long stalks,the velocity of the cargo decreases slowly with the increase in the ratio of Ndc80 to kinesin number.Our results thus give an explanation of why the kinesin motors working in the cell have long stalks.展开更多
癌症高表达蛋白(highly expressed in cancer,Hec1)是一种动粒蛋白,它通过N末端尾巴区与微管间的静电相互作用促进动粒-微管结构的形成。Hec1蛋白与Nuf2p、Spc24p、Spc25p构成Ndc80复合物,Ndc80定位于动粒外板,和其他的动粒蛋白共同作用...癌症高表达蛋白(highly expressed in cancer,Hec1)是一种动粒蛋白,它通过N末端尾巴区与微管间的静电相互作用促进动粒-微管结构的形成。Hec1蛋白与Nuf2p、Spc24p、Spc25p构成Ndc80复合物,Ndc80定位于动粒外板,和其他的动粒蛋白共同作用,参与调节有丝分裂中染色体的正常分离。Hec1蛋白表达量随着细胞周期动态变化,且在分裂旺盛的细胞如肿瘤细胞中高表达。目前Hec1已成为肿瘤基因治疗的靶点,使用不同的病毒载体,如腺病毒载体、腺相关病毒载体、逆转录病毒载体将Hec1的干扰片段导入宫颈瘤或脑胶质瘤细胞后,可引起肿瘤细胞凋亡。展开更多
Recent experiments revealing possible nanoscale electrostatic interactions in force generation at kinetochores for chromosome motions have prompted speculation regarding possible models for interactions between positi...Recent experiments revealing possible nanoscale electrostatic interactions in force generation at kinetochores for chromosome motions have prompted speculation regarding possible models for interactions between positively charged molecules in kinetochores and negative charge on C-termini near the plus ends of microtubules. A clear picture of how kinetochores establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. The molecular cell biology paradigm requires that specific molecules, or molecular geometries, for force generation be identified. However, it is possible to account for mitotic chromosome motions within a systems approach in terms of experimentally known cellular electric charge distributions interacting over nanometer distances.展开更多
The mechanism by which chromosomes establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. Equally challenging is an explanation for the ti...The mechanism by which chromosomes establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. Equally challenging is an explanation for the timing of poleward, antipoleward, and oscillatory chromosome movements. The molecular cell biology paradigm requires that specific molecules, or molecular geometries, for force generation are necessary for chromosome motions. We propose here that the dynamics of mitotic chromosome motions are an emergent property of a changing intracellular pH in combination with electrostatic forces. We explain this mechanism within the context of Complexity Theory, based on the electrostatic properties of tubulin, known cellular electric charge distributions, and the dynamic instability of microtubules.展开更多
基金Health Bureau of Nantong City,No.WQ2016011Nantong Science and Technology Bureau,No.MS22015105+2 种基金National Natural Science Foundation of China,No.81601842Science and Technology Development Project of Nantong City,China,No.HS2014061Jiangsu Provincial Commission of Health and Family Planning,No.H201453
文摘AIM To investigate the role of nuclear division cycle(NDC)80in human hepatocellular carcinogenesis.METHODS NDC80 gene expression was analyzed by real-time reverse transcription polymerase chain reaction in 47paired hepatocellular carcinoma(HCC)and adjacent tissues.The HCC cell line SMMC-7721 was transfected with lentivirus to silence endogenous NDC80 gene expression,which was confirmed by real-time polymerase chain reaction and western blotting.The effects of NDC80silencing on SMMC-7721 cell proliferation were evaluated by Cellomics Array Scan VTI imaging.Cell cycle analysis and apoptosis were detected with flow cytometry.Colony formation was assessed by fluorescence microscopy.RESULTS NDC80 expression levels in HCC tissues were significantly higher than those in the adjacent tissues.Functional studies demonstrated that NDC80 silencing significantly reduced SMMC-7721 cell proliferation and colony formation.Knockdown of NDC80 resulted in increased apoptosis and cell cycle arrest at S-phase.NDC80 contributed to HCC progression by reducing apoptosis and overcoming cell cycle arrest. CONCLUSION Elevated expression of NDC80 may play a role in promoting the development of HCC.
基金supported by the National Key R&D Program of China(2017YFA 0102900 and 2017 YFA 0503600)the National Natural Science Fondation of China(31671407 and 31871359 to Z.D.+4 种基金31621002,31430054,91854203,and 31320103904 to X.Y.31301099 and 21672201 to X.G.31471275 to D.W.),Strategic Priority Research Program of the Chinese Academy of Sciences(XDB19040000)Chinese Academy of Sciences Center for Excellence in Molecular Cell Science(2015 HSC-UE010)MOE Innovative Team(IRT_17R102).
文摘Error-free mitosis depends on accurate chromosome attachment to spindle microtubules,which is monitored by the spindle assembly checkpoint(SAC)signaling.As an upstream factor of SAC,the precise and dynamic kinetochore localization of Mps1 kinase is critical for initiating and silencing SAC signaling.However,the underlying molecular mechanism remains elusive.Here,we demonstrated that the multisite interactions between Mps1 and Ndc80 complex(Ndc80C)govern Mps1 kinetochore targeting.Importantly,we identified direct interaction between Mps1 tetratricopeptide repeat domain and Ndc80C.We further identified that Mps1 C-terminal fragment,which contains the protein kinase domain and C-tail,enhances Mps1 kinetochore localization.Mechanistically,Mps1 C-terminal fragment mediates its dimerization.Perturbation of C-tail attenuates the kinetochore targeting and activity of Mps1,leading to aberrant mitosis due to compromised SAC function.Taken together,our study highlights the importance of Mps1 dimerization and multisite interactions with Ndc80C in enabling responsive SAC signaling.
文摘In eukaryote cells,cargos are often transported cooperatively by kinesin motors and nonmotor microtubule-associated proteins(MAPs).The prior in vitro experimental data showed that the velocity of the cargo transported by kinesin motors and Ndc80(a member of MAP)proteins of truncated coiled-coil stalks decreases sensitively with the increase of the ratio of Ndc80 to motor number.However,the underlying mechanism of Ndc80 affecting sensitively the cooperative cargo transport by kinesin motors is unclear.To understand the mechanism,here we study numerically the cooperative cargo transport by kinesin motors and Ndc80 proteins.Our results showed that for the case of the motors and Ndc80 proteins with truncated short stalks,as used in the experiments,the calculated results reproduce quantitatively the prior experimental data.The mechanism of the cargo velocity decreasing sensitively with the ratio of Ndc80 to motor number is revealed.By contrast,for the case of the motors and Ndc80 proteins with full-length long stalks,the velocity of the cargo decreases slowly with the increase in the ratio of Ndc80 to kinesin number.Our results thus give an explanation of why the kinesin motors working in the cell have long stalks.
文摘癌症高表达蛋白(highly expressed in cancer,Hec1)是一种动粒蛋白,它通过N末端尾巴区与微管间的静电相互作用促进动粒-微管结构的形成。Hec1蛋白与Nuf2p、Spc24p、Spc25p构成Ndc80复合物,Ndc80定位于动粒外板,和其他的动粒蛋白共同作用,参与调节有丝分裂中染色体的正常分离。Hec1蛋白表达量随着细胞周期动态变化,且在分裂旺盛的细胞如肿瘤细胞中高表达。目前Hec1已成为肿瘤基因治疗的靶点,使用不同的病毒载体,如腺病毒载体、腺相关病毒载体、逆转录病毒载体将Hec1的干扰片段导入宫颈瘤或脑胶质瘤细胞后,可引起肿瘤细胞凋亡。
文摘Recent experiments revealing possible nanoscale electrostatic interactions in force generation at kinetochores for chromosome motions have prompted speculation regarding possible models for interactions between positively charged molecules in kinetochores and negative charge on C-termini near the plus ends of microtubules. A clear picture of how kinetochores establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. The molecular cell biology paradigm requires that specific molecules, or molecular geometries, for force generation be identified. However, it is possible to account for mitotic chromosome motions within a systems approach in terms of experimentally known cellular electric charge distributions interacting over nanometer distances.
文摘The mechanism by which chromosomes establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. Equally challenging is an explanation for the timing of poleward, antipoleward, and oscillatory chromosome movements. The molecular cell biology paradigm requires that specific molecules, or molecular geometries, for force generation are necessary for chromosome motions. We propose here that the dynamics of mitotic chromosome motions are an emergent property of a changing intracellular pH in combination with electrostatic forces. We explain this mechanism within the context of Complexity Theory, based on the electrostatic properties of tubulin, known cellular electric charge distributions, and the dynamic instability of microtubules.
