Mitosin/CENP-F is a human nuclear protein transiently associated with the outer kinetochore plate in M phase and is involved in M phase progression. LEK1 and CMF1, which are its murine and chicken orthologs, however, ...Mitosin/CENP-F is a human nuclear protein transiently associated with the outer kinetochore plate in M phase and is involved in M phase progression. LEK1 and CMF1, which are its murine and chicken orthologs, however, are implicated in muscle differentiation and reportedly not distributed at kinetochores.We therefore conducted several assays to clarify this issue. The typical centromere staining patterns were observed in mitotic cells from both human primary culture and murine, canine, and mink cell lines. A C-terminal portion of LEK1 also conferred centromere localization. Our analysis further suggests conserved kinetochore localization of mammalian mitosin orthologs. Moreover, mitosin was associated preferentially with kinetochores of unaligned chromosomes. It was also constantly transported from kinetochores to spindle poles by cytoplasmic dynein. These properties resemble those of other kinetochore proteins important for the spindle checkpoint, thus implying a role of mitosin in this checkpoint. Therefore, mitosin family may serve as multifunctional proteins involved in both mitosis and differentiation.展开更多
Accurate chromosome segregation in mitosis depends on kinetochores that connect centromeric chromatin to spindle microtubules.Centromeres are captured by individual microtubules via a kinetochore constitutive centrome...Accurate chromosome segregation in mitosis depends on kinetochores that connect centromeric chromatin to spindle microtubules.Centromeres are captured by individual microtubules via a kinetochore constitutive centromere-associated network(CCAN)during chromosome segregation.CCAN contains 16 subunits,including CENP-W and CENP-T.However,the molecular recognition and mitotic regulation of the CCAN assembly remain elusive.Here,we revealed that CENP-W binds to the histone fold domain and an uncharacterized N-terminal region of CENP-T.Aurora B phosphorylates CENP-W at threonine 60,which enhances the interaction between CENP-W and CENP-T to ensure robust metaphase chromosome alignment and accurate chromosome segregation in mitosis.These findings delineate a conserved signaling cascade that integrates protein phosphorylation with CCAN integrity for the maintenance of genomic stability.展开更多
Stable transmission of genetic information during cell division requires faithful chromosome segregation.Mounting evidence has demonstrated that polo-like kinase 1(PLK1)dynamics at kinetochores control correct kinetoc...Stable transmission of genetic information during cell division requires faithful chromosome segregation.Mounting evidence has demonstrated that polo-like kinase 1(PLK1)dynamics at kinetochores control correct kinetochore–microtubule attachments and subsequent silencing of the spindle assembly checkpoint.However,the mechanisms underlying PLK1-mediated silencing of the spindle checkpoint remain elusive.Here,we identified a regulatory mechanism by which PLK1-elicited zeste white 10(ZW10)phosphorylation regulates spindle checkpoint silencing in mitosis.ZW10 is a cognate substrate of PLK1,and the phosphorylation of ZW10 at Ser12 enables dynamic ZW10–Zwint1 interactions.Inhibition of ZW10 phosphorylation resulted in misaligned chromosomes,while persistent expression of phospho-mimicking ZW10 mutant caused premature anaphase,in which sister chromatids entangled as cells entered anaphase.These findings reveal the previously uncharacterized PLK1–ZW10 interaction through which dynamic phosphorylation of ZW10 fine-tunes accurate chromosome segregation in mitosis.展开更多
Spindle checkpoint is an important biochemical signaling cascade during mitosis which monitors the fidelity of chromosome segregation, and is mediated by protein kinases Mpsl and Bubl/BubRl. Our recent studies show th...Spindle checkpoint is an important biochemical signaling cascade during mitosis which monitors the fidelity of chromosome segregation, and is mediated by protein kinases Mpsl and Bubl/BubRl. Our recent studies show that kinesin-related motor protein CENP-E interacts with BubRl and participates in spindle checkpoint signaling. To elucidate the molecular mechanisms underlying spindle checkpoint signaling, we carried out proteomic dissection of human cell kinetochore and revealed protein kinase TTK, human homologue of yeast Mpsl. Our studies show that TTK is localized to the kinetochore of human cells, and interacts with CENP-E, suggesting that TTK may play an important role in chromosome segregation during mitosis.展开更多
Wide species crosses often result in uniparental genome elimination and visible failures in centromere func- tion. Crosses involving lines with mutated forms of the CENH3 histone variant that organizes the centromere/...Wide species crosses often result in uniparental genome elimination and visible failures in centromere func- tion. Crosses involving lines with mutated forms of the CENH3 histone variant that organizes the centromere/ kinetochore interface have been shown to have similar effects, inducing haploids at high frequencies. Here, we propose a simple centromere size model that endeavors to explain both observations. It is based on the idea of a quantitative centromere architecture where each centromere in an individual is the same size, and the average size is dictated by a natural equilibrium between bound and unbound CENH3 （and its chaperones or binding proteins）. While centromere size is determined by the cellular milieu, centromere positions are heritable and defined by the interactions of a small set of proteins that bind to both DNA and CENH3. Lines with defective or mutated CENH3 have a lower loading capacity and support smaller centromeres. In cases where a line with small or defective centromeres is crossed to a line with larger or normal centromeres, the smaller/defective centromeres are selectively degraded or not maintained, resulting in chromosome loss from the small-centromere parent. The model is testable and generalizable, and helps to explain the coun- terintuitive observation that inducer lines do not induce haploids when crossed to themselves.展开更多
For proper chromosome segregation, all kinetochores must achieve bipolar microtubule （MT） attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynact...For proper chromosome segregation, all kinetochores must achieve bipolar microtubule （MT） attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynactin binds kinetoehores in prometaphase and has long been implicated in chromosome congression. Unfortunately, inactivation of dynein usually disturbs spindle organization, thus hampering evaluation of its kinetochore roles. Here we specifically eliminated kinetochore dynein/dynactin by RNAi-mediated depletion of ZW10, a protein essential for kinetochore localization of the motor. Time-lapse microscopy indicated markedly-reduced congression efficiency, though congressing chromosomes displayed similar velocities as in control cells. Moreover, cells frequently failed to achieve full chromosome alignment, despite their normal spindles. Confocal microcopy revealed that the misaligned kinetochores were monooriented or unattached and mostly lying outside the spindle, suggesting a difficulty to capture MTs from the opposite pole. Kinetoehores on monoastral spindles were dispersed farther away from the pole and exhibited only mild oscillation. Furthermore, inactivating dynein by other means generated similar phenotypes. Therefore, kinetochore dynein produces on monooriented kinetochores a poleward pulling force, which may contribute to efficient bipolar attachment by facilitating their proper microtubule captures to promote congression as well as full chromosome alignment.展开更多
Chromosome segregation in mitosis is orchestrated by the interaction of the kinetochore with spindle microtubules. Our recent study shows that NEK2A interacts with MAD 1 at the kinetochore and possibly functions as a ...Chromosome segregation in mitosis is orchestrated by the interaction of the kinetochore with spindle microtubules. Our recent study shows that NEK2A interacts with MAD 1 at the kinetochore and possibly functions as a novel integrator of spindle checkpoint signaling. However, it is unclear how NEK2A regulates kinetochore-microtubule attachment in mitosis. Here we show that NEK2A phosphorylates human Sgo 1 and such phosphorylation is essential for faithful chromosome congression in mitosis. NEK2A binds directly to HsSgol in vitro and co-distributes with HsSgol to the kinetochore of mitotic cells. Our in vitro phosphorylation experiment demonstrated that HsSgo 1 is a substrate of NEK2A and the phosphorylation sites were mapped to Ser^14 and Ser^507 as judged by the incorporation of 32^P. Although such phosphorylation is not required for assembly of HsSgo 1 to the kinetochore, expression of non-phosphorylatable mutant HsSgo 1 perturbed chromosome congression and resulted in a dramatic increase in microtubule attachment errors, including syntelic and monotelic attachments. These findings reveal a key role for the NEK2A-mediated phosphorylation ofHsSgo 1 in orchestrating dynamic kinetochore-microtubule interaction. We propose that NEK2A-mediated phosphorylation of human Sgo 1 provides a link between centromeric cohesion and spindle microtubule attachment at the kinetochores.展开更多
It is generally believed that the equal distribution of genetic materials to two daughter cells during mitosis is the key to cell health and development. During the dynamic process, spindle checkpoint plays a very imp...It is generally believed that the equal distribution of genetic materials to two daughter cells during mitosis is the key to cell health and development. During the dynamic process, spindle checkpoint plays a very important role in chromosome movements and final sister chromatid separation. The equal and precise segregation of chromosomes contributes to the genomic stability while aberrant separations result in chromosome instability that causes pathogenesis of certain diseases such as Down’s syndrome and cancers. Kinetochore and its regulatory proteins consist of the spindle checkpoint and determine the spatial and temporal orders of chromosome segregation.展开更多
The kinetochore is structurally composed offour layers. We know that three microtubule-based motorproteins such as CENP-E, dynein, and MCAK are located at the outmost region of the kinetochore. Experimentation ofthese...The kinetochore is structurally composed offour layers. We know that three microtubule-based motorproteins such as CENP-E, dynein, and MCAK are located at the outmost region of the kinetochore. Experimentation ofthese motor functions betters our understanding of mitotic regulation, and chromosome movements in particular.With real-time studies of chromosome movements in livecells, we hope to illustrate the molecular mechanisms under-lying mitotic regulation.展开更多
Shugoshin-1(Sgo1)is necessary for maintaining sister centromere cohesion and ensuring accurate chromosome segregation during mitosis.It has been reported that the localization of Sgo1 at the centromere is dependent on...Shugoshin-1(Sgo1)is necessary for maintaining sister centromere cohesion and ensuring accurate chromosome segregation during mitosis.It has been reported that the localization of Sgo1 at the centromere is dependent on Bub1-mediated phosphorylation of histone H2A at T120.However,it remains uncertain whether other centromeric proteins play a role in regulating the localization and function of Sgo1 during mitosis.Here,we show that CENP-A interacts with Sgo1 and determines the localization of Sgo1 to the centromere during mitosis.Further biochemical characterization revealed that lysine and arginine residues in the C-terminal domain of Sgo1 are critical for binding CENP-A.Interestingly,the replacement of these basic amino acids with acidic amino acids perturbed the localization of Sgo1 and Aurora B to the centromere,resulting in aberrant chromosome segregation and premature chromatid separation.Taken together,these findings reveal a previously unrecognized but direct link between Sgo1 and CENP-A in centromere plasticity control and illustrate how the Sgo1–CENP-A interaction guides accurate cell division.展开更多
Double haploid production is the most effective way to create true-breeding lines in a single generation.In Arabidopsis,haploid induction via mutation of the centromere-specific histone H3(cenH3)has been shown when th...Double haploid production is the most effective way to create true-breeding lines in a single generation.In Arabidopsis,haploid induction via mutation of the centromere-specific histone H3(cenH3)has been shown when the mutant is outcrossed to the wild-type,and the wild-type genome remains in the haploid progeny.However,factors that affect haploid induction are still poorly understood.Here,we report that a mutant of the cenH3 assembly factor Kinetochore Null2(KNL2)can be used as a haploid inducer when pollinated by the wild-type.We discovered that short-term temperature stress of the knl2 mutant increased the efficiency of haploid induction 10-fold.We also demonstrated that a point mutation in the CENPC-k motif of KNL2 is sufficient to generate haploid-inducing lines,suggesting that haploidinducing lines in crops can be identified in a naturally occurring or chemically induced mutant population,avoiding the generic modification(GM)approach at any stage.Furthermore,a cenh3-4 mutant functioned as a haploid inducer in response to short-term heat stress,even though it did not induce haploids under standard conditions.Thus,we identified KNL2 as a new target gene for the generation of haploid-inducer lines and showed that exposure of centromeric protein mutants to high temperature strongly increases their haploid induction efficiency.展开更多
Entry into mitosis is driven by signaling cascades of mitotic kinases.Our recent studies show that TTK,a kinetochore-associated protein kinase,interacts with CENP-E,a mitotic kinesin located to corona fiber ofkinetoch...Entry into mitosis is driven by signaling cascades of mitotic kinases.Our recent studies show that TTK,a kinetochore-associated protein kinase,interacts with CENP-E,a mitotic kinesin located to corona fiber ofkinetochore.Using immunoelectron microscopy,here we show that TTK is present at the nuclear pore adjacent complex of interphase HeLa cells.Upon nuclear envelope fragmentation,TTK targets to the outermostregion of the developing kinetochores ofmonoorient chromosome as well as to spindle poles.After stable attachment,throughout chromosome congression,TTK is a constituent of the corona fibers,extending up to 90 nm away from the kinetochore outer plate.Upon metaphase alignment,TTK departs from the kinetochore and migrates toward the centrosomes.Taken together,this evidence strongly supports a model in which TTK functions in spindle checkpoint signaling cascades at both kinetochore and centrosome.展开更多
A new model for mitotic dynamics of eukaryotic cells is proposed. In the kinetochore mo-tor-midzone motor model two kinds of motors, the kinetochore motors and the midzone motors, play important roles in chromosome mo...A new model for mitotic dynamics of eukaryotic cells is proposed. In the kinetochore mo-tor-midzone motor model two kinds of motors, the kinetochore motors and the midzone motors, play important roles in chromosome movement. Using this model the chromosome congression during prometaphase, the chromosome oscillation during metaphase and the chromatid segregation during anaphase are described in a unified way.展开更多
基金supported by grants 97JC14006 from Shanghai Committee of Science and Technology(No.30025021,39970160,and 39500030)from the Natural Science Foundation of ChinaKSCX2-2-02 from Chinese Academy of Sciences.
文摘Mitosin/CENP-F is a human nuclear protein transiently associated with the outer kinetochore plate in M phase and is involved in M phase progression. LEK1 and CMF1, which are its murine and chicken orthologs, however, are implicated in muscle differentiation and reportedly not distributed at kinetochores.We therefore conducted several assays to clarify this issue. The typical centromere staining patterns were observed in mitotic cells from both human primary culture and murine, canine, and mink cell lines. A C-terminal portion of LEK1 also conferred centromere localization. Our analysis further suggests conserved kinetochore localization of mammalian mitosin orthologs. Moreover, mitosin was associated preferentially with kinetochores of unaligned chromosomes. It was also constantly transported from kinetochores to spindle poles by cytoplasmic dynein. These properties resemble those of other kinetochore proteins important for the spindle checkpoint, thus implying a role of mitosin in this checkpoint. Therefore, mitosin family may serve as multifunctional proteins involved in both mitosis and differentiation.
基金supported by the National Key Research and Development Program of China(2022YFA1303100,2022YFA0806800,2022YFA1302700,and 2017YFA0503600)the National Natural Science Foundation of China(32090040,92254302,92153302,92253301,22137007,32170733,and 31871359)+3 种基金the Ministry of Education(IRT_17R102)the Plans for Major Provincial Science&Technology Projects of Anhui Province(202303a0702003)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB19040000)the Fundamental Research Funds for the Central Universities(WK2070000066 and WK2070000194).
文摘Accurate chromosome segregation in mitosis depends on kinetochores that connect centromeric chromatin to spindle microtubules.Centromeres are captured by individual microtubules via a kinetochore constitutive centromere-associated network(CCAN)during chromosome segregation.CCAN contains 16 subunits,including CENP-W and CENP-T.However,the molecular recognition and mitotic regulation of the CCAN assembly remain elusive.Here,we revealed that CENP-W binds to the histone fold domain and an uncharacterized N-terminal region of CENP-T.Aurora B phosphorylates CENP-W at threonine 60,which enhances the interaction between CENP-W and CENP-T to ensure robust metaphase chromosome alignment and accurate chromosome segregation in mitosis.These findings delineate a conserved signaling cascade that integrates protein phosphorylation with CCAN integrity for the maintenance of genomic stability.
基金supported by grants from the Ministry of Science and Technology of China and the National Natural Science Foundation of China(2022YFA1303100,32090040,92254302,2022YFA0806800,91854203,31621002,2017YFA0503600,21922706,and 92153302 to X.L.92053104 to X.G.)+2 种基金the Plans for Major Provincial Science&Technology Projects of Anhui Province(202303a0702003 to X.L.)the Ministry of Education(IRT_17R102 to X.L.)the Fundamental Research Funds for the Central Universities(KB9100000007 and KB9100000013 to X.L.)。
文摘Stable transmission of genetic information during cell division requires faithful chromosome segregation.Mounting evidence has demonstrated that polo-like kinase 1(PLK1)dynamics at kinetochores control correct kinetochore–microtubule attachments and subsequent silencing of the spindle assembly checkpoint.However,the mechanisms underlying PLK1-mediated silencing of the spindle checkpoint remain elusive.Here,we identified a regulatory mechanism by which PLK1-elicited zeste white 10(ZW10)phosphorylation regulates spindle checkpoint silencing in mitosis.ZW10 is a cognate substrate of PLK1,and the phosphorylation of ZW10 at Ser12 enables dynamic ZW10–Zwint1 interactions.Inhibition of ZW10 phosphorylation resulted in misaligned chromosomes,while persistent expression of phospho-mimicking ZW10 mutant caused premature anaphase,in which sister chromatids entangled as cells entered anaphase.These findings reveal the previously uncharacterized PLK1–ZW10 interaction through which dynamic phosphorylation of ZW10 fine-tunes accurate chromosome segregation in mitosis.
基金This work was supported in part by the National Natural Science Foundation of China(Grant No.39925018)the Key Project of the Chinese Academy of Sciences(Grant No.KSCX2-2-01).
文摘Spindle checkpoint is an important biochemical signaling cascade during mitosis which monitors the fidelity of chromosome segregation, and is mediated by protein kinases Mpsl and Bubl/BubRl. Our recent studies show that kinesin-related motor protein CENP-E interacts with BubRl and participates in spindle checkpoint signaling. To elucidate the molecular mechanisms underlying spindle checkpoint signaling, we carried out proteomic dissection of human cell kinetochore and revealed protein kinase TTK, human homologue of yeast Mpsl. Our studies show that TTK is localized to the kinetochore of human cells, and interacts with CENP-E, suggesting that TTK may play an important role in chromosome segregation during mitosis.
文摘Wide species crosses often result in uniparental genome elimination and visible failures in centromere func- tion. Crosses involving lines with mutated forms of the CENH3 histone variant that organizes the centromere/ kinetochore interface have been shown to have similar effects, inducing haploids at high frequencies. Here, we propose a simple centromere size model that endeavors to explain both observations. It is based on the idea of a quantitative centromere architecture where each centromere in an individual is the same size, and the average size is dictated by a natural equilibrium between bound and unbound CENH3 （and its chaperones or binding proteins）. While centromere size is determined by the cellular milieu, centromere positions are heritable and defined by the interactions of a small set of proteins that bind to both DNA and CENH3. Lines with defective or mutated CENH3 have a lower loading capacity and support smaller centromeres. In cases where a line with small or defective centromeres is crossed to a line with larger or normal centromeres, the smaller/defective centromeres are selectively degraded or not maintained, resulting in chromosome loss from the small-centromere parent. The model is testable and generalizable, and helps to explain the coun- terintuitive observation that inducer lines do not induce haploids when crossed to themselves.
基金Acknowledgments The authors thank Qiongping Huang, Lirong Liu, and Wei Bian for technical assistance. We are grateful to Drs G Chan （Cross Cancer Institute, University of Alberta, Edmonton Alberta, Canada） for antibodies to human ZW 10 and Rod, KH Choo （Murdoch Children＇s Research Institute, Royal Children＇s Hospital, Melbourne, Australia） for anti-CREST serum, and E Fuchs （Rockefeller University, USA） for mRFP cDNA. This work was supported by the National Science Foundation of China （30330330, 30421005, and 30623003）, Ministry of Science and Technology of China （2005CB522703 and 2007CB914501）, and the Shanghai Municipal Council for Science and Technology （S048014317, 06DZ22032, and 058014578）.
文摘For proper chromosome segregation, all kinetochores must achieve bipolar microtubule （MT） attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynactin binds kinetoehores in prometaphase and has long been implicated in chromosome congression. Unfortunately, inactivation of dynein usually disturbs spindle organization, thus hampering evaluation of its kinetochore roles. Here we specifically eliminated kinetochore dynein/dynactin by RNAi-mediated depletion of ZW10, a protein essential for kinetochore localization of the motor. Time-lapse microscopy indicated markedly-reduced congression efficiency, though congressing chromosomes displayed similar velocities as in control cells. Moreover, cells frequently failed to achieve full chromosome alignment, despite their normal spindles. Confocal microcopy revealed that the misaligned kinetochores were monooriented or unattached and mostly lying outside the spindle, suggesting a difficulty to capture MTs from the opposite pole. Kinetoehores on monoastral spindles were dispersed farther away from the pole and exhibited only mild oscillation. Furthermore, inactivating dynein by other means generated similar phenotypes. Therefore, kinetochore dynein produces on monooriented kinetochores a poleward pulling force, which may contribute to efficient bipolar attachment by facilitating their proper microtubule captures to promote congression as well as full chromosome alignment.
基金We thank members of our group for insightful discussion during the course of this study.This work was supported by grants from Chinese Academy of Science(KSCX1-YW-R65,KSCX2-YW-H10)National Basic Research Program of China(2002CB713700)+4 种基金Hi-Tech Research and Development Program of China(2001AA215331)Chinese Minister of Education(20020358051 to XY,PCSIRT0413 to XD)National Natural Science Foundation of China(39925018,30270293 to XY,30500183 to XD,30600222 to JY)National Institutes of Health(USA)(DK56292,CA92080)to XY(a Georgia Cancer Coalition Eminent Scholar)JY was supported by China Postdoctor(2005037560).
文摘Chromosome segregation in mitosis is orchestrated by the interaction of the kinetochore with spindle microtubules. Our recent study shows that NEK2A interacts with MAD 1 at the kinetochore and possibly functions as a novel integrator of spindle checkpoint signaling. However, it is unclear how NEK2A regulates kinetochore-microtubule attachment in mitosis. Here we show that NEK2A phosphorylates human Sgo 1 and such phosphorylation is essential for faithful chromosome congression in mitosis. NEK2A binds directly to HsSgol in vitro and co-distributes with HsSgol to the kinetochore of mitotic cells. Our in vitro phosphorylation experiment demonstrated that HsSgo 1 is a substrate of NEK2A and the phosphorylation sites were mapped to Ser^14 and Ser^507 as judged by the incorporation of 32^P. Although such phosphorylation is not required for assembly of HsSgo 1 to the kinetochore, expression of non-phosphorylatable mutant HsSgo 1 perturbed chromosome congression and resulted in a dramatic increase in microtubule attachment errors, including syntelic and monotelic attachments. These findings reveal a key role for the NEK2A-mediated phosphorylation ofHsSgo 1 in orchestrating dynamic kinetochore-microtubule interaction. We propose that NEK2A-mediated phosphorylation of human Sgo 1 provides a link between centromeric cohesion and spindle microtubule attachment at the kinetochores.
基金This work was supported partly by the State Funds for Outstanding Young Scientists (Granted No. 39925018)the Chinese Academy of Sciences (Grant No. KSCX2-2-01).
文摘It is generally believed that the equal distribution of genetic materials to two daughter cells during mitosis is the key to cell health and development. During the dynamic process, spindle checkpoint plays a very important role in chromosome movements and final sister chromatid separation. The equal and precise segregation of chromosomes contributes to the genomic stability while aberrant separations result in chromosome instability that causes pathogenesis of certain diseases such as Down’s syndrome and cancers. Kinetochore and its regulatory proteins consist of the spindle checkpoint and determine the spatial and temporal orders of chromosome segregation.
文摘The kinetochore is structurally composed offour layers. We know that three microtubule-based motorproteins such as CENP-E, dynein, and MCAK are located at the outmost region of the kinetochore. Experimentation ofthese motor functions betters our understanding of mitotic regulation, and chromosome movements in particular.With real-time studies of chromosome movements in livecells, we hope to illustrate the molecular mechanisms under-lying mitotic regulation.
基金supported by grants from the Ministry of Science and Technology of China(2022YFA1303100,2022YFA0806800,2022YFA1302700,and 2017YFA0503600)the National Natural Science Foundation of China(32090040,92254302,92153302,32170733,31621002,and 22177106)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB19040000 and XDB37010105)the Ministry of Education(IRT_17R102,20113402130010,and YD2070006001).
文摘Shugoshin-1(Sgo1)is necessary for maintaining sister centromere cohesion and ensuring accurate chromosome segregation during mitosis.It has been reported that the localization of Sgo1 at the centromere is dependent on Bub1-mediated phosphorylation of histone H2A at T120.However,it remains uncertain whether other centromeric proteins play a role in regulating the localization and function of Sgo1 during mitosis.Here,we show that CENP-A interacts with Sgo1 and determines the localization of Sgo1 to the centromere during mitosis.Further biochemical characterization revealed that lysine and arginine residues in the C-terminal domain of Sgo1 are critical for binding CENP-A.Interestingly,the replacement of these basic amino acids with acidic amino acids perturbed the localization of Sgo1 and Aurora B to the centromere,resulting in aberrant chromosome segregation and premature chromatid separation.Taken together,these findings reveal a previously unrecognized but direct link between Sgo1 and CENP-A in centromere plasticity control and illustrate how the Sgo1–CENP-A interaction guides accurate cell division.
基金supported by the National Key R&D Program of China (2022YFA1303100, 2022YFA0806800)the National Natural Science Foundation of China (32090040, 31621002, 31871359, 32170733, 92153302)+1 种基金the Ministry of Education (IRT_17R102, 20113402130010, YD2070006001)the Fundamental Research Funds for the Central Universities (WK2070000194)
基金supported by the German Federal Ministry of Education and Research(Plant 2030,Project 031B0192NN,HaploTools)the Deutsche Forschungsgemeinschaft(LE2299/3-1 and LE2299/5-1)the European Regional Development Fund-Project"REMAP"(CZ.02.1.01/0.0/0.0/15_003/0000479)to K.R.
文摘Double haploid production is the most effective way to create true-breeding lines in a single generation.In Arabidopsis,haploid induction via mutation of the centromere-specific histone H3(cenH3)has been shown when the mutant is outcrossed to the wild-type,and the wild-type genome remains in the haploid progeny.However,factors that affect haploid induction are still poorly understood.Here,we report that a mutant of the cenH3 assembly factor Kinetochore Null2(KNL2)can be used as a haploid inducer when pollinated by the wild-type.We discovered that short-term temperature stress of the knl2 mutant increased the efficiency of haploid induction 10-fold.We also demonstrated that a point mutation in the CENPC-k motif of KNL2 is sufficient to generate haploid-inducing lines,suggesting that haploidinducing lines in crops can be identified in a naturally occurring or chemically induced mutant population,avoiding the generic modification(GM)approach at any stage.Furthermore,a cenh3-4 mutant functioned as a haploid inducer in response to short-term heat stress,even though it did not induce haploids under standard conditions.Thus,we identified KNL2 as a new target gene for the generation of haploid-inducer lines and showed that exposure of centromeric protein mutants to high temperature strongly increases their haploid induction efficiency.
基金supported by grants from the Chinese Outstanding Young Scientist Award(39925018)the Chinese Academy of Science(KSCX2-2-01)+1 种基金the Chinese 973 project(2002CB713700)the American Cancer Society(RPG59282)to XY.
文摘Entry into mitosis is driven by signaling cascades of mitotic kinases.Our recent studies show that TTK,a kinetochore-associated protein kinase,interacts with CENP-E,a mitotic kinesin located to corona fiber ofkinetochore.Using immunoelectron microscopy,here we show that TTK is present at the nuclear pore adjacent complex of interphase HeLa cells.Upon nuclear envelope fragmentation,TTK targets to the outermostregion of the developing kinetochores ofmonoorient chromosome as well as to spindle poles.After stable attachment,throughout chromosome congression,TTK is a constituent of the corona fibers,extending up to 90 nm away from the kinetochore outer plate.Upon metaphase alignment,TTK departs from the kinetochore and migrates toward the centrosomes.Taken together,this evidence strongly supports a model in which TTK functions in spindle checkpoint signaling cascades at both kinetochore and centrosome.
文摘A new model for mitotic dynamics of eukaryotic cells is proposed. In the kinetochore mo-tor-midzone motor model two kinds of motors, the kinetochore motors and the midzone motors, play important roles in chromosome movement. Using this model the chromosome congression during prometaphase, the chromosome oscillation during metaphase and the chromatid segregation during anaphase are described in a unified way.
