CYCLIN A POTENTIATES MATURATION-PROMOTING FACTOR ACTIVATION IN THE EARLY XENOPUS EMBRYO VIA INHIBITION OF THE TYROSINE KINASE THAT PHOSPHORYLATES CDC2
CYCLIN A POTENTIATES MATURATION-PROMOTING FACTOR ACTIVATION IN THE EARLY XENOPUS EMBRYO VIA INHIBITION OF THE TYROSINE KINASE THAT PHOSPHORYLATES CDC2
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DOI：
10.1083/jcb.118.5.1109
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发表时间：
1992-09-01
影响因子：
7.8
通讯作者：
DOREE, M
中科院分区：
文献类型：
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作者：
DEVAULT, A;FESQUET, D;DOREE, M
我们已经在大肠杆菌中产生了人类细胞周期蛋白A，并研究了它是如何产生H1 kistone激酶活性时，添加到从孤雌激活爪蟾卵制备的无细胞周期蛋白提取物。发现细胞周期蛋白A与cdc 2形成主要复合物，并且仅很差地结合cdk 2/Eg 1。没有检测到滞后期之间的时间，当加入细胞周期蛋白A和H1组蛋白激酶的活性时，在青蛙提取物中产生的时间，即使在2 mM钒酸盐的存在下，这块cdc 25的活性。使用从海星卵母细胞制备的提取物获得了基本相同的结果。我们的结论是，形成一个活跃的细胞周期蛋白A-cdc 2激酶在早期发展逃脱抑制机制，延迟形成一个活跃的细胞周期蛋白B-cdc 2激酶。这种抑制机制涉及cdc 2在酪氨酸15上的磷酸化。即使在存在钒酸盐的情况下，冈田酸（OA）也能激活细胞周期蛋白B-cdc 2激酶，并强烈降低细胞周期蛋白B相关cdc 2的酪氨酸磷酸化。6-二甲基氨基嘌呤，丝氨酸-苏氨酸激酶的抑制剂，抑制OA依赖的细胞周期蛋白B-cdc 2复合物的激活。我们还发现，细胞周期蛋白B-或细胞周期蛋白A-cdc 2激酶可以诱导或加速细胞周期蛋白B-cdc 2复合物从失活激酶转化为活性激酶。细胞周期蛋白B相关的cdc 2不进行可检测的磷酸化酪氨酸在鸡蛋提取物中含有活性细胞周期蛋白A-cdc 2激酶，即使在钒酸盐的存在下。我们提出，活性周期蛋白A-cdc 2激酶产生的新合成的周期蛋白A和cdc 2没有滞后期可能会导致快速开关的平衡周期蛋白B-cdc 2复合物的酪氨酸脱磷酸化和活性形式的cdc 2在早期发展，由于强烈抑制cdc 2特异性酪氨酸激酶（S）。这可以解释为什么早期细胞周期在许多物种中如此之快。
We have produced human cyclin A in Escherichia coli and investigated how it generates H1 kistone kinase activity when added to cyclin-free extracts prepared from parthenogenetically activated Xenopus eggs. Cyclin A was found to form a major complex with cdc2, and to bind cdk2/Eg1 only poorly. No lag phase was detected between the time when cyclin A was added and the time when H1 histone kinase activity was produced in frog extracts, even in the presence of 2 mM vanadate, which blocks cdc25 activity. Essentially identical results were obtained using extracts prepared from starfish oocytes. We conclude that formation of an active cyclin A-cdc2 kinase during early development escapes an inhibitory mechanism that delays formation of an active cyclin B-cdc2 kinase. This inhibitory mechanism involves phosphorylation of cdc2 on tyrosine 15. Okadaic acid (OA) activated cyclin B-cdc2 kinase and strongly reduced tyrosine phosphorylation of cyclin B-associated cdc2, even in the presence of vanadate. 6-dimethylaminopurine, a reported inhibitor of serine-threonine kinases, suppressed OA-dependent activation of cyclin B-cdc2 complexes. This indicates that the kinase(s) which phosphorylate(s) cdc2 on inhibitory sites can be inactivated by a phosphorylation event, itself antagonized by an OA-sensitive, most likely type 2A phosphatase.We also found that cyclin B- or cyclin A-cdc2 kinases can induce or accelerate conversion of the cyclin B-cdc2 complex from an inactive into an active kinase. Cyclin B-associated cdc2 does not undergo detectable phosphorylation on tyrosine in egg extracts containing active cyclin A-cdc2 kinase, even in the presence of vanadate. We propose that the active cyclin A-cdc2 kinase generated without a lag phase from neo-synthesized cyclin A and cdc2 may cause a rapid switch in the equilibrium of cyclin B-cdc2 complexes to the tyrosine-dephosphorylated and active form of cdc2 during early development, owing to strong inhibition of the cdc2-specific tyrosine kinase(s). This may explain why early cell cycles are so rapid in many species.