Physarum polycephalum L., a naturally synchronized myxomycophyta, was demonstrated to contain a cyclin B1-like protein by Western blot and immunoelectron microscopy. The content and subcellular location of the protein...Physarum polycephalum L., a naturally synchronized myxomycophyta, was demonstrated to contain a cyclin B1-like protein by Western blot and immunoelectron microscopy. The content and subcellular location of the protein varied during the cell cycle. The cyclin B1-like protein was first detected in the plasmodia of S phase while it did not appear in the nuclei until late G2 phase. The content of the protein in both the plasmodia and nuclei rose gradually onwards, peaked at metaphase and disappeared abruptly at ana-telophase. The protein was found to be distributed in both the cytoplasm and nuclei in late G2 phase and metaphase. In nuclei, the protein was mainly located in the chromosomal and nucleolar areas. The results suggest that the cyclin B1-like protein of P. polycephalum begins to be synthesized at S phase, enters the nuclei at late G2 phase, accumulates in both cytoplasm and nuclei onwards and breaks down at ana-telophase. The results also suggest that the cyclin B1-like protein acts as a cytoplasmic-nuclear protein during certain phases of the cell cycle.展开更多
Cyclin B1 is a key regulatory protein controlling cell cycle progression in vertebrates. Cyclin B1 binds CDK1, a cy-clin-dependent kinase catalytic subunit, forming a complex that orchestrates mitosis through phosphor...Cyclin B1 is a key regulatory protein controlling cell cycle progression in vertebrates. Cyclin B1 binds CDK1, a cy-clin-dependent kinase catalytic subunit, forming a complex that orchestrates mitosis through phosphorylation of key proteins. Cyclin B1 regulates both the activation of CDK1 and its subcellular localization, which may be critical for substrate selection. Here, we demonstrate that cyclin B1 is concentrated on the outer plate of the kinetochore during prometaphase. This localization requires the cyclin box region of the protein. Cyclin B1 is displaced from individual kinetochores to the spindle poles by microtubule attachment to the kinetochores, and this displacement is dependent on the dynein/dynactin complex. Depletion of cyclin B1 by vector-based siRNA causes inefficient attachment between kinetochores and microtubules, and chromosome alignment defects, and delays the onset of anaphase. We conclude that cyclin B1 accumulates at kinetochores during prometaphase, where it contributes to the correct attachment of mi- crotubules to kinetochores and efficient alignment of the chromosomes, most likely through localized phosphorylation of specific substrates by cyclin B1-CDK1. Cyclin B1 is then transported from each kinetochore as microtubule attachment is completed, and this relocalization may redirect the activity of cyclin B1-CDK1 and contribute to inactivation of the spindle assembly checkpoint.展开更多
Objective To evaluate the effect of dynein inhibitor on mouse oocyte in vitro maturation and its cyclin B1 transcription level. Methods Immature mouse oocytes were cultured in vitro with a known dynein ATPase activ...Objective To evaluate the effect of dynein inhibitor on mouse oocyte in vitro maturation and its cyclin B1 transcription level. Methods Immature mouse oocytes were cultured in vitro with a known dynein ATPase activity inhibitor-sodium orthovanadate (SOV) to detect the changes of maturation rate, and semi-quantitative RT-PCR and single cell RT-PCR were performed to detect the changes of cyclin B1 mRNA level. Results In dose-dependent experiments, the maturation rates of oocytes were significantly different between 5 mmol/L SOV and control groups (P<0.05), and decreased with SOV increasing doses. However, the elevation of cyclin B1 mRNA level of immatured oocytes cultured for 12 h depended on SOV concentrations ranging from 50 to 500 mmol/L. In incon- tinuity exposed SOV experiments, the maturation rates of oocytes markedly reduced after the first incubation with 400 mmol/L SOV at least for 1 h and were first cultured in SOV-free medium for 4 h or 8 h before exposure to SOV (P<0.05). In time-course experiment, the opposite changes of cyclin B1 mRNA level in oocytes between SOV and control groups were observed. Conclusion Dynein inhibitor might delay oocytes meiosis process, and cause ectopic expression of cyclin B1 in oocytes. Most Oocytes incubated with SOV blocked at germinal vesicles (GV) stage or MⅠto anaphase transition due to dynein dysfunction and ectopic transcription level of cyclin B1.展开更多
Objective: To study the relationship between the expression of human cyclin B1 in colorectal carcinomas and the pathological characters. Methods: The Expression of cyclin B1 in 66 cases of colorectal carcinomas were d...Objective: To study the relationship between the expression of human cyclin B1 in colorectal carcinomas and the pathological characters. Methods: The Expression of cyclin B1 in 66 cases of colorectal carcinomas were detected by flow cytometry and immunohistochemistry. Then the relationship between the expression of cyclin B1 in colorectal carcinomas and pathological characters was analyzed with statistics. Results: The expression of cyclin B1 in colorectal carcinomas had associa- tivity with the cancer cell differentiation (P<0.05); However, the expression of cyclin B1 in colorectal carcinomas had no obvious associativity with cancer cell infiltrate depth and lymph nodes metastasis (P>0.05). Conclusion: In the colorectal cancers with high expression of cyclin B1, the cancer cells would present high differentiation; with low expression of cyclin B1 the cancer cells would present low differentiation. Along with the expression of cyclin B1 from high to low, the cancer cells differentiation has the tendency from high to low too.展开更多
Objective:We studied the expression of cyclin B1 and survivin in human non-small cell lung cancer(NSCLC),and the relationship between such expression and clinicopathological features of NSCLC.Methods:One hundred cases...Objective:We studied the expression of cyclin B1 and survivin in human non-small cell lung cancer(NSCLC),and the relationship between such expression and clinicopathological features of NSCLC.Methods:One hundred cases of tissue specimen including NSCLC,neighboring noncancerous tissue and normal lung tissue were collected at random.These specimens were detected by immunohistochemical methods.Results:The expression of cyclin B1 and survivin showed significant difference(P < 0.01) between NSCLC tissues,proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues,and normal lung tissues.Compared with normal lung tissues,there was an overexpression of cyclin B1 and survivin in NSCLC and an enhancing expression of cyclin B1 and survivin in proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues.Significantly positive correlation was found between the overexpression of cyclin B1 and that of survivin in 100 NSCLC cases(P < 0.01).The significantly positive correlation was also found between the enhancing expression of cyclin B1 and that of survivin in proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues(P < 0.01).No statistical significance was found between the different histological types,the differentiated degree,lymphatic metastasis and the expression of cyclin B1 and survivin(P > 0.05) in NSCLC.Statistical significance was marked between different clinical stages of NSCLC and the expression of cyclin B1 and survivin(P < 0.05).Conclusion:The overexpression of cyclin B1 and survivin was found in NSCLC.The expression of cyclin B1 and survivin might be up-regulated during an early step of tumorigenesis and during the development of NSCLC.The progression of cell cycle could be efficiently connected with the control of apoptosis by the interrelations between the overexpression of cyclin B1 and that of survivin in NSCLC during the G2/M phase.The overexpression of cyclin B1 and survivin might be used as marker in showing the dividing and proliferating ability,and the inhibiting apoptosis ability(lengthening cell lifespan) of NSCLC.Moreover,the overexpression of cyclin B1 and survivin was associated with the clinic stages of NSCLC.展开更多
p34cdc2 and Cyclin B1 are key components of cell cycle controlling machine and are believed to play a fundamental role in gametogenesis. It is also well known that, in scrotal mammals, spermatogenesis depends greatly ...p34cdc2 and Cyclin B1 are key components of cell cycle controlling machine and are believed to play a fundamental role in gametogenesis. It is also well known that, in scrotal mammals, spermatogenesis depends greatly on the maintenance of comparatively low temperature in the scrotum. To investigate whether the expression of cdc2 and Cyclin B1 in spermatogenic cells during spermatogenesis is actually a temperature dependent event, in situ hybridization, Western blotting and immunohistochemistry analysis were used to study the expression of cdc2 and Cyclin B1 in normal and cryptorchid testis. Results showed that the abdominal temperature had no significant influence on the transcription of cdc2 and Cyclin B1 in the spermatogonia and pachytene/diplotene primary spermatocytes, but it blocked the translation of them. Due to the deficiency of p34cdc2 and Cyclin B1, the spermatogonia and pachytene/diplotene primary spermatocytes were unable to form MPF, hence, they couldn’t undergo karyokinesis. The development of primary spermatocytes was arrested at the G2 to M phase transition. We also found that testosterone could regulate the Cyclin B1 expression in spermatogenic cells. Muscular injection of testosterone could recover spermatogenesis in the unilateral scrotal testis which was influenced by the contralateral cryptorchid testis, but it could not salvage the spermatogenesis block in the cryptorchid testis.展开更多
文摘Physarum polycephalum L., a naturally synchronized myxomycophyta, was demonstrated to contain a cyclin B1-like protein by Western blot and immunoelectron microscopy. The content and subcellular location of the protein varied during the cell cycle. The cyclin B1-like protein was first detected in the plasmodia of S phase while it did not appear in the nuclei until late G2 phase. The content of the protein in both the plasmodia and nuclei rose gradually onwards, peaked at metaphase and disappeared abruptly at ana-telophase. The protein was found to be distributed in both the cytoplasm and nuclei in late G2 phase and metaphase. In nuclei, the protein was mainly located in the chromosomal and nucleolar areas. The results suggest that the cyclin B1-like protein of P. polycephalum begins to be synthesized at S phase, enters the nuclei at late G2 phase, accumulates in both cytoplasm and nuclei onwards and breaks down at ana-telophase. The results also suggest that the cyclin B1-like protein acts as a cytoplasmic-nuclear protein during certain phases of the cell cycle.
文摘Cyclin B1 is a key regulatory protein controlling cell cycle progression in vertebrates. Cyclin B1 binds CDK1, a cy-clin-dependent kinase catalytic subunit, forming a complex that orchestrates mitosis through phosphorylation of key proteins. Cyclin B1 regulates both the activation of CDK1 and its subcellular localization, which may be critical for substrate selection. Here, we demonstrate that cyclin B1 is concentrated on the outer plate of the kinetochore during prometaphase. This localization requires the cyclin box region of the protein. Cyclin B1 is displaced from individual kinetochores to the spindle poles by microtubule attachment to the kinetochores, and this displacement is dependent on the dynein/dynactin complex. Depletion of cyclin B1 by vector-based siRNA causes inefficient attachment between kinetochores and microtubules, and chromosome alignment defects, and delays the onset of anaphase. We conclude that cyclin B1 accumulates at kinetochores during prometaphase, where it contributes to the correct attachment of mi- crotubules to kinetochores and efficient alignment of the chromosomes, most likely through localized phosphorylation of specific substrates by cyclin B1-CDK1. Cyclin B1 is then transported from each kinetochore as microtubule attachment is completed, and this relocalization may redirect the activity of cyclin B1-CDK1 and contribute to inactivation of the spindle assembly checkpoint.
基金This work was supported by a grant from the National Natural Science Foundation of China (No. 30170481).
文摘Objective To evaluate the effect of dynein inhibitor on mouse oocyte in vitro maturation and its cyclin B1 transcription level. Methods Immature mouse oocytes were cultured in vitro with a known dynein ATPase activity inhibitor-sodium orthovanadate (SOV) to detect the changes of maturation rate, and semi-quantitative RT-PCR and single cell RT-PCR were performed to detect the changes of cyclin B1 mRNA level. Results In dose-dependent experiments, the maturation rates of oocytes were significantly different between 5 mmol/L SOV and control groups (P<0.05), and decreased with SOV increasing doses. However, the elevation of cyclin B1 mRNA level of immatured oocytes cultured for 12 h depended on SOV concentrations ranging from 50 to 500 mmol/L. In incon- tinuity exposed SOV experiments, the maturation rates of oocytes markedly reduced after the first incubation with 400 mmol/L SOV at least for 1 h and were first cultured in SOV-free medium for 4 h or 8 h before exposure to SOV (P<0.05). In time-course experiment, the opposite changes of cyclin B1 mRNA level in oocytes between SOV and control groups were observed. Conclusion Dynein inhibitor might delay oocytes meiosis process, and cause ectopic expression of cyclin B1 in oocytes. Most Oocytes incubated with SOV blocked at germinal vesicles (GV) stage or MⅠto anaphase transition due to dynein dysfunction and ectopic transcription level of cyclin B1.
基金Supported by grants from the State Key Basic Research Development Program of China (973 program, No. 2004CB518705) and the Science Foundation Ministry of Health, China (Cell cycle diagnosis and analysis of clinic tumor III).
文摘Objective: To study the relationship between the expression of human cyclin B1 in colorectal carcinomas and the pathological characters. Methods: The Expression of cyclin B1 in 66 cases of colorectal carcinomas were detected by flow cytometry and immunohistochemistry. Then the relationship between the expression of cyclin B1 in colorectal carcinomas and pathological characters was analyzed with statistics. Results: The expression of cyclin B1 in colorectal carcinomas had associa- tivity with the cancer cell differentiation (P<0.05); However, the expression of cyclin B1 in colorectal carcinomas had no obvious associativity with cancer cell infiltrate depth and lymph nodes metastasis (P>0.05). Conclusion: In the colorectal cancers with high expression of cyclin B1, the cancer cells would present high differentiation; with low expression of cyclin B1 the cancer cells would present low differentiation. Along with the expression of cyclin B1 from high to low, the cancer cells differentiation has the tendency from high to low too.
基金Supported by a grant from the Science and Technology Department of Liaoning Province (No. 2010225034)
文摘Objective:We studied the expression of cyclin B1 and survivin in human non-small cell lung cancer(NSCLC),and the relationship between such expression and clinicopathological features of NSCLC.Methods:One hundred cases of tissue specimen including NSCLC,neighboring noncancerous tissue and normal lung tissue were collected at random.These specimens were detected by immunohistochemical methods.Results:The expression of cyclin B1 and survivin showed significant difference(P < 0.01) between NSCLC tissues,proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues,and normal lung tissues.Compared with normal lung tissues,there was an overexpression of cyclin B1 and survivin in NSCLC and an enhancing expression of cyclin B1 and survivin in proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues.Significantly positive correlation was found between the overexpression of cyclin B1 and that of survivin in 100 NSCLC cases(P < 0.01).The significantly positive correlation was also found between the enhancing expression of cyclin B1 and that of survivin in proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues(P < 0.01).No statistical significance was found between the different histological types,the differentiated degree,lymphatic metastasis and the expression of cyclin B1 and survivin(P > 0.05) in NSCLC.Statistical significance was marked between different clinical stages of NSCLC and the expression of cyclin B1 and survivin(P < 0.05).Conclusion:The overexpression of cyclin B1 and survivin was found in NSCLC.The expression of cyclin B1 and survivin might be up-regulated during an early step of tumorigenesis and during the development of NSCLC.The progression of cell cycle could be efficiently connected with the control of apoptosis by the interrelations between the overexpression of cyclin B1 and that of survivin in NSCLC during the G2/M phase.The overexpression of cyclin B1 and survivin might be used as marker in showing the dividing and proliferating ability,and the inhibiting apoptosis ability(lengthening cell lifespan) of NSCLC.Moreover,the overexpression of cyclin B1 and survivin was associated with the clinic stages of NSCLC.
基金National Natural Science FOundation of China.Grant! Nos: 39770370, 39630160We are grateful to Dr. A. Koff and Dr. J. Pines f
文摘p34cdc2 and Cyclin B1 are key components of cell cycle controlling machine and are believed to play a fundamental role in gametogenesis. It is also well known that, in scrotal mammals, spermatogenesis depends greatly on the maintenance of comparatively low temperature in the scrotum. To investigate whether the expression of cdc2 and Cyclin B1 in spermatogenic cells during spermatogenesis is actually a temperature dependent event, in situ hybridization, Western blotting and immunohistochemistry analysis were used to study the expression of cdc2 and Cyclin B1 in normal and cryptorchid testis. Results showed that the abdominal temperature had no significant influence on the transcription of cdc2 and Cyclin B1 in the spermatogonia and pachytene/diplotene primary spermatocytes, but it blocked the translation of them. Due to the deficiency of p34cdc2 and Cyclin B1, the spermatogonia and pachytene/diplotene primary spermatocytes were unable to form MPF, hence, they couldn’t undergo karyokinesis. The development of primary spermatocytes was arrested at the G2 to M phase transition. We also found that testosterone could regulate the Cyclin B1 expression in spermatogenic cells. Muscular injection of testosterone could recover spermatogenesis in the unilateral scrotal testis which was influenced by the contralateral cryptorchid testis, but it could not salvage the spermatogenesis block in the cryptorchid testis.
