During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between t...During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between the separating chromatids is required for the initiation and execution ofcytokinesis. Central spindle organization requires mitotic kinesins, the chromosomal passenger protein complex, and microtubule bundling protein PRC 1. PRC 1 is phosphorylated by Cdc2 at Thr470 and Thr481 during mitosis. However, the functional relevance of PRC 1 phosphorylation at Thr470 has remained elusive. Here we show that expression of the non-phosphorylatable mutant PRC 1T470A but not the phospho-mimicking mutant PRC 1^T470E causes aberrant organization of the central spindle. Immunoprecipitation experiment indicates that both PRC 1^T470A and PRC 1^T470E mutant proteins associate with wild-type PRC 1, suggesting that phosphorylation of Thr470 does not alter PRC 1 self-association. In addition, in vitro co-sedimentation experiment showed that PRC 1 binds to microtubule independent of the phosphorylation state of Thr470. Gel-filtration experiment suggested that phosphorylation of Thr470 promotes oligomerization of PRC 1. Given the fact that prevention of the Thr470 phosphorylation inhibits PRC 1 oligomerization in vitro and causes an aberrant organization of central spindle in vivo, we propose that this phosphorylation-dependent PRC 1 oligomerization ensures that central spindle assembly occurs at the appropriate time in the cell cycle.展开更多
目的:研究悬浮红细胞(preserved red cells,PRC)保存期间IL-1、IL-6、IL-8、TNF-α水平的变化,观察保存前滤除白细胞对其保存水平的影响。方法:将32名健康献血员的32单位悬浮红细胞各分成两份,其中一份于保存前滤除白细胞,另一份不做任...目的:研究悬浮红细胞(preserved red cells,PRC)保存期间IL-1、IL-6、IL-8、TNF-α水平的变化,观察保存前滤除白细胞对其保存水平的影响。方法:将32名健康献血员的32单位悬浮红细胞各分成两份,其中一份于保存前滤除白细胞,另一份不做任何处理,分别放置于4℃保存并在保存的不同阶段测定其IL-1、IL-6、IL-8、TNF-α水平。结果:悬浮红细胞中IL-1、IL-6、IL-8、TNF-α水平随保存时间延长而增高,保存前滤除白细胞后悬浮红细胞保存期间IL-1、IL-6、IL-8、TNF-α水平无明显升高。结论:IL-1、IL-6、IL-8、TNF-α在悬浮红细胞保存中存在产生和累积,而滤除白细胞可抑制IL-1、IL-6、IL-8、TNF-α在悬浮红细胞保存期间的产生和累积,对预防非溶血性发热输血反应有一定作用。展开更多
Polycomb group genes play crucial roles in the maintenance of the transcriptionally silenced state of genes for proper cell differentiation in animals and plants. While components of the polycomb repressive complex2 ...Polycomb group genes play crucial roles in the maintenance of the transcriptionally silenced state of genes for proper cell differentiation in animals and plants. While components of the polycomb repressive complex2 （PRC2） are evolutionarily conserved and their functions are extensively studied in plants, PRCI differs considerably between animals and plants, and its functions in plants are as yet not well described. Previous studies have identified the Arabidopsis AtRINGla and AtRINGlb as homologues of the animal PRC1 subunit RING1. Here, we show that the Atringla Atringlb double mutant exhibits derepression of embryonic traits during vegetative growth. Accordingly, several key regulatory genes involved in embryogenesis and stem cell activity are ectopically expressed in the mutant. Furthermore, we show that the mutant phenotypes and increased expression of regulatory genes are enhanced by the PRC2 mutant c/f. Finally, we show that three homologues of the animal PRCl-subunit ring-finger protein BMI1, AtBMIIa, AtBMIlb and AtBMIlc, can bind with AtRINGla or AtRINGIb, and in addition, AtBMIlc can bind with LHP1. The Atbmila Atbmilb double mutant shows derepression of embryonic traits similar to that of the Atringla Atringlb double mutant. Interestingly, expression levels of AtBMIla, AtBMIlb and AtBMIlc are elevated in the Atringla Atringlb mutant and those of AtBMIlc, AtRINGla and AtRINGlb are elevated in the Atbmila Atbmilb mu- tant, suggesting a self-regulatory feedback mechanism. Taken together, our results illuminate crucial functions of the PRCl-like ring-finger components in stable repression of embryonic traits and regulatory genes for proper somatic growth.展开更多
Dear Editor,Polycomb group(Pc G)proteins represent important roles in repressing gene expression throughout development.The Polycomb repressive complexes(PRCs)have been subdivided into two central protein complexes,PR...Dear Editor,Polycomb group(Pc G)proteins represent important roles in repressing gene expression throughout development.The Polycomb repressive complexes(PRCs)have been subdivided into two central protein complexes,PRC1 and PRC2.PRC1 catalyzes H2AK119ub and PRC2catalyzes H3K27me1/2/3(Fursova et al.,2019).PRC1 is further categorized as CBX-containing canonical PRC1(c PRC1)and RYBP/YAF2-containing variant PRC1(v PRC1)(Blackledge and Klose,2021).展开更多
基金National Natural Science Foundation of China （39925018, 90508002 , 30121001） Chinese Academy of Science （KSCX 1-R65 and RSCX2-H10）+2 种基金 National Basic Research Program of China （973 project, 2002CB713700） American Cancer Society （RPG-99-173-01） a Gcc Breast Cancer Research award and National Institutes of Health grants DK56292 and CA89019 to XY （a GCC Eminent Scholar） and NS36194 （JW）.
文摘During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between the separating chromatids is required for the initiation and execution ofcytokinesis. Central spindle organization requires mitotic kinesins, the chromosomal passenger protein complex, and microtubule bundling protein PRC 1. PRC 1 is phosphorylated by Cdc2 at Thr470 and Thr481 during mitosis. However, the functional relevance of PRC 1 phosphorylation at Thr470 has remained elusive. Here we show that expression of the non-phosphorylatable mutant PRC 1T470A but not the phospho-mimicking mutant PRC 1^T470E causes aberrant organization of the central spindle. Immunoprecipitation experiment indicates that both PRC 1^T470A and PRC 1^T470E mutant proteins associate with wild-type PRC 1, suggesting that phosphorylation of Thr470 does not alter PRC 1 self-association. In addition, in vitro co-sedimentation experiment showed that PRC 1 binds to microtubule independent of the phosphorylation state of Thr470. Gel-filtration experiment suggested that phosphorylation of Thr470 promotes oligomerization of PRC 1. Given the fact that prevention of the Thr470 phosphorylation inhibits PRC 1 oligomerization in vitro and causes an aberrant organization of central spindle in vivo, we propose that this phosphorylation-dependent PRC 1 oligomerization ensures that central spindle assembly occurs at the appropriate time in the cell cycle.
文摘目的:研究悬浮红细胞(preserved red cells,PRC)保存期间IL-1、IL-6、IL-8、TNF-α水平的变化,观察保存前滤除白细胞对其保存水平的影响。方法:将32名健康献血员的32单位悬浮红细胞各分成两份,其中一份于保存前滤除白细胞,另一份不做任何处理,分别放置于4℃保存并在保存的不同阶段测定其IL-1、IL-6、IL-8、TNF-α水平。结果:悬浮红细胞中IL-1、IL-6、IL-8、TNF-α水平随保存时间延长而增高,保存前滤除白细胞后悬浮红细胞保存期间IL-1、IL-6、IL-8、TNF-α水平无明显升高。结论:IL-1、IL-6、IL-8、TNF-α在悬浮红细胞保存中存在产生和累积,而滤除白细胞可抑制IL-1、IL-6、IL-8、TNF-α在悬浮红细胞保存期间的产生和累积,对预防非溶血性发热输血反应有一定作用。
文摘Polycomb group genes play crucial roles in the maintenance of the transcriptionally silenced state of genes for proper cell differentiation in animals and plants. While components of the polycomb repressive complex2 （PRC2） are evolutionarily conserved and their functions are extensively studied in plants, PRCI differs considerably between animals and plants, and its functions in plants are as yet not well described. Previous studies have identified the Arabidopsis AtRINGla and AtRINGlb as homologues of the animal PRC1 subunit RING1. Here, we show that the Atringla Atringlb double mutant exhibits derepression of embryonic traits during vegetative growth. Accordingly, several key regulatory genes involved in embryogenesis and stem cell activity are ectopically expressed in the mutant. Furthermore, we show that the mutant phenotypes and increased expression of regulatory genes are enhanced by the PRC2 mutant c/f. Finally, we show that three homologues of the animal PRCl-subunit ring-finger protein BMI1, AtBMIIa, AtBMIlb and AtBMIlc, can bind with AtRINGla or AtRINGIb, and in addition, AtBMIlc can bind with LHP1. The Atbmila Atbmilb double mutant shows derepression of embryonic traits similar to that of the Atringla Atringlb double mutant. Interestingly, expression levels of AtBMIla, AtBMIlb and AtBMIlc are elevated in the Atringla Atringlb mutant and those of AtBMIlc, AtRINGla and AtRINGlb are elevated in the Atbmila Atbmilb mu- tant, suggesting a self-regulatory feedback mechanism. Taken together, our results illuminate crucial functions of the PRCl-like ring-finger components in stable repression of embryonic traits and regulatory genes for proper somatic growth.
基金supported by the National Natural Science Foundation of China(31925009,U21A20195)the National Key Research and Development Program of China(2021YFA1100300)。
文摘Dear Editor,Polycomb group(Pc G)proteins represent important roles in repressing gene expression throughout development.The Polycomb repressive complexes(PRCs)have been subdivided into two central protein complexes,PRC1 and PRC2.PRC1 catalyzes H2AK119ub and PRC2catalyzes H3K27me1/2/3(Fursova et al.,2019).PRC1 is further categorized as CBX-containing canonical PRC1(c PRC1)and RYBP/YAF2-containing variant PRC1(v PRC1)(Blackledge and Klose,2021).
