Nuclear envelope breakdown is under nuclear not cytoplasmic control in sea urchin zygotes.
Nuclear envelope breakdown is under nuclear not cytoplasmic control in sea urchin zygotes.
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DOI：
10.1083/jcb.129.6.1447
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发表时间：
1995-06
影响因子：
7.8
通讯作者：
MILLER, FJ
中科院分区：
文献类型：
--
作者：
SLUDER, G;THOMPSON, EA;RIEDER, CL;MILLER, FJ
核膜破裂（NEB）和进入有丝分裂是由p34cdc2-细胞周期蛋白B激酶复合物或有丝分裂促进因子（MPF）的激活驱动的。监测有丝分裂的基本准备事件（如DNA复制）的检查点控制机制被认为通过下调MPF激活来阻止有丝分裂进入，直到这些事件完成。因此，我们惊讶地发现，当用Colcemid阻断海胆受精卵的原核融合时，雌性原核始终比雄性原核先分解。这不是由于强积金激活时间的区域差异，因为相互接触的原核在相同程度上异步分解。为了测试NEB是否在细胞核或细胞质水平上受到控制，我们在受精前用补骨脂素处理卵子或精子，以共价交联碱基配对的DNA链，从而激活了雌性和雄性原核中分别完成DNA合成的检查点。当只有母系DNA交联时，雄性原核首先分解。当精子DNA交联时，相对于女性原核分解，男性原核分解大大延迟，有时甚至不会发生。在这种具有接触原核的受精卵中，雌性NEB后的球粒蛋白失活产生由母体染色体和父亲中心体组成的功能纺锤体。在整个有丝分裂过程中，完整的雄性原核仍然位于一个位置。在其他实验中，当补骨脂素处理过的精子核，超过90%的受精卵核在对照后至少2小时内不分解，即使H1组蛋白激酶活性逐渐上升，接近或高于对照有丝分裂水平。用阿霉素阻断DNA合成的正常受精卵也是如此。从这些结果中，我们得出结论，海胆受精卵中的NEB在核水平而不是细胞质水平上受到控制，并且细胞质MPF活性的有丝分裂水平不足以驱动处于检查点控制下的细胞核的NEB。我们的研究结果还表明，完成DNA合成的检查点主要通过在细胞核内抑制NEB，而不是通过下调细胞质MPF的活性。
Nuclear envelope breakdown (NEB) and entry into mitosis are though to be driven by the activation of the p34cdc2-cyclin B kinase complex or mitosis promoting factor (MPF). Checkpoint control mechanisms that monitor essential preparatory events for mitosis, such as DNA replication, are thought to prevent entry into mitosis by downregulating MPF activation until these events are completed. Thus, we were surprised to find that when pronuclear fusion in sea urchin zygotes is blocked with Colcemid, the female pronucleus consistently breaks down before the male pronucleus. This is not due to regional differences in the time of MPF activation, because pronuclei touching each other break down asynchronously to the same extent. To test whether NEB is controlled at the nuclear or cytoplasmic level, we activated the checkpoint for the completion of DNA synthesis separately in female and male pronuclei by treating either eggs or sperm before fertilization with psoralen to covalently cross-link base-paired strands of DNA. When only the maternal DNA is cross-linked, the male pronucleus breaks down first. When the sperm DNA is cross-linked, male pronuclear breakdown is substantially delayed relative to female pronuclear breakdown and sometimes does not occur. Inactivation of the Colcemid after female NEB in such zygotes with touching pronuclei yields a functional spindle composed of maternal chromosomes and paternal centrosomes. The intact male pronucleus remains located at one aster throughout mitosis. In other experiments, when psoralen-treated sperm nuclei, over 90% of the zygote nuclei do not break down for at least 2 h after the controls even though H1 histone kinase activity gradually rises close to, or higher than, control mitotic levels. The same is true for normal zygotes treated with aphidicolin to block DNA synthesis. From these results, we conclude that NEB in sea urchin zygotes is controlled at the nuclear, not cytoplasmic, level, and that mitotic levels of cytoplasmic MPF activity are not sufficient to drive NEB for a nucleus that is under checkpoint control. Our results also demonstrate that the checkpoint for the completion of DNA synthesis inhibits NEB by acting primarily within the nucleus, not by downregulating the activity of cytoplasmic MPF.
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DOI：
10.1083/jcb.115.1.1
发表时间：
1991-10
期刊：
The Journal of cell biology
影响因子：
--
作者：
Pines J;Hunter T
通讯作者：
Hunter T
影响因子：
7.8
作者：
FUSELER, JW
通讯作者：
FUSELER, JW
影响因子：
2.5
作者：
MCDONALD, K;MORPHEW, MK
通讯作者：
MORPHEW, MK
DOI：
10.1083/jcb.123.6.1649
发表时间：
1993-12
期刊：
The Journal of cell biology
影响因子：
--
作者：
Melchior F;Paschal B;Evans J;Gerace L
通讯作者：
Gerace L
DOI：
10.1073/pnas.90.8.3521
发表时间：
1993-04-15
影响因子：
11.1
作者：
SEBASTIAN, B;KAKIZUKA, A;HUNTER, T
通讯作者：
HUNTER, T