1997年2月,英国生物学家首次用羊的体细胞成功地克隆出一只小母羊叫'多利'。此事之后至今,克隆一直为世人广泛观注。其实克隆技术的历史有100多年了,今天克隆出一只小羊就能引起这么大的反响,原因是提供细胞核的这个细胞是 B ...1997年2月,英国生物学家首次用羊的体细胞成功地克隆出一只小母羊叫'多利'。此事之后至今,克隆一直为世人广泛观注。其实克隆技术的历史有100多年了,今天克隆出一只小羊就能引起这么大的反响,原因是提供细胞核的这个细胞是 B 羊的一个乳腺细胞——普通体细胞。已经高度分化了的体细胞,一般不具有再分化的能力。以前克隆出动物的细胞都是具有分化能力的胚胎细胞。展开更多
Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated cellular process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In both h...Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated cellular process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In both human and fission yeast (Schizosaccharomyces pombe) cells, the activity of Cdc2 is regulated in part by the phosphorylation status of tyrosine 15 (Tyr15) on Cdc2, which is phosphorylated by Wee1 kinase during late G2 and is rapidly dephosphorylated by the Cdc25 tyrosine phosphatase to trigger entry into mitosis. These Cdc2 regulators are the downstream targets of two well- characterized G2/M checkpoint pathways which prevent cells from entering mitosis when cellular DNA is damaged or when DNA replication is inhibited. Increasing evidence suggests that Cdc2 is also commonly targeted by viral proteins, which modulate host cell cycle machinery to benefit viral survival or replication. In this review, we describe the effect of viral protein R (Vpr) encoded by human immunodeficiency virus type 1 (HIV-1) on cell cycle G2/M regulation. Based on our current knowledge about this viral effect, we hypothesize that Vpr induces cell cycle G2 arrest through a mechanism that is to some extent different from the classic G2/M checkpoints. One the unique features distinguishing Vpr-induced G2 arrest from the classic checkpoints is the role of phosphatase 2A (PP2A) in Vpr-induced G2 arrest. Interestingly, PP2A is targeted by a number of other viral proteins including SV40 small T antigen, polyomavirus T antigen, HTLV Tax and adenovirus E4orf4. Thus an in-depth understanding of the molecular mechanisms underlying Vpr-induced G2 arrest will provide additional insights into the basic biology of cell cycle G2/M regulation and into the biological significance of this effect during host-pathogen interactions.展开更多
Objective： To construct a non-replicating vaccinia virus expressing human papillomavirus 16 （HPV16） L1, L2E7 proteins as a candidate vaccine for cervical cancer. Methods： Using vaccinia virus vector, we generated ...Objective： To construct a non-replicating vaccinia virus expressing human papillomavirus 16 （HPV16） L1, L2E7 proteins as a candidate vaccine for cervical cancer. Methods： Using vaccinia virus vector, we generated a strain of non-replicating recombinant vaccinia virus vaccine expressing HPV16 L1, L2E7 proteins by homologous recombination and identified by PCR and Westernloting. Results： We demonstrated that the L1, L2E7 gene of HPV16 were integrated into vaccinia genosome and could express L1, L2E7 protein stably when infected the CEF using PCR and Western-blot assay. Conclusion： NTVJL1/L2E7 can express L1, L2E7 protein of HPV16 and can be taken as a candidate vaccine for HPV16-associated diseases.展开更多
文摘1997年2月,英国生物学家首次用羊的体细胞成功地克隆出一只小母羊叫'多利'。此事之后至今,克隆一直为世人广泛观注。其实克隆技术的历史有100多年了,今天克隆出一只小羊就能引起这么大的反响,原因是提供细胞核的这个细胞是 B 羊的一个乳腺细胞——普通体细胞。已经高度分化了的体细胞,一般不具有再分化的能力。以前克隆出动物的细胞都是具有分化能力的胚胎细胞。
基金supported in part by grants from the National Institute of Health GM89630 and AI63080an endowed Research Scholar Chair by the Medical Research Institute Councilby an internal grant of the University of Maryland Medical Center(RYZ).
文摘Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated cellular process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In both human and fission yeast (Schizosaccharomyces pombe) cells, the activity of Cdc2 is regulated in part by the phosphorylation status of tyrosine 15 (Tyr15) on Cdc2, which is phosphorylated by Wee1 kinase during late G2 and is rapidly dephosphorylated by the Cdc25 tyrosine phosphatase to trigger entry into mitosis. These Cdc2 regulators are the downstream targets of two well- characterized G2/M checkpoint pathways which prevent cells from entering mitosis when cellular DNA is damaged or when DNA replication is inhibited. Increasing evidence suggests that Cdc2 is also commonly targeted by viral proteins, which modulate host cell cycle machinery to benefit viral survival or replication. In this review, we describe the effect of viral protein R (Vpr) encoded by human immunodeficiency virus type 1 (HIV-1) on cell cycle G2/M regulation. Based on our current knowledge about this viral effect, we hypothesize that Vpr induces cell cycle G2 arrest through a mechanism that is to some extent different from the classic G2/M checkpoints. One the unique features distinguishing Vpr-induced G2 arrest from the classic checkpoints is the role of phosphatase 2A (PP2A) in Vpr-induced G2 arrest. Interestingly, PP2A is targeted by a number of other viral proteins including SV40 small T antigen, polyomavirus T antigen, HTLV Tax and adenovirus E4orf4. Thus an in-depth understanding of the molecular mechanisms underlying Vpr-induced G2 arrest will provide additional insights into the basic biology of cell cycle G2/M regulation and into the biological significance of this effect during host-pathogen interactions.
基金Support by a grant from the National High Technology Research and Development Program, China (No.2002AA216041).
文摘Objective： To construct a non-replicating vaccinia virus expressing human papillomavirus 16 （HPV16） L1, L2E7 proteins as a candidate vaccine for cervical cancer. Methods： Using vaccinia virus vector, we generated a strain of non-replicating recombinant vaccinia virus vaccine expressing HPV16 L1, L2E7 proteins by homologous recombination and identified by PCR and Westernloting. Results： We demonstrated that the L1, L2E7 gene of HPV16 were integrated into vaccinia genosome and could express L1, L2E7 protein stably when infected the CEF using PCR and Western-blot assay. Conclusion： NTVJL1/L2E7 can express L1, L2E7 protein of HPV16 and can be taken as a candidate vaccine for HPV16-associated diseases.
