Initiation of nuclear DNA replication: evidence for formation of committed prereplicative cellular state.
Initiation of nuclear DNA replication: evidence for formation of committed prereplicative cellular state.
复制标题
核 DNA 复制的启动：形成定向复制前细胞状态的证据。
DOI：
10.1073/pnas.78.9.5677
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发表时间：
1981
影响因子：
11.1
通讯作者：
Das,M
中科院分区：
文献类型：
--
作者：
Das,M
本文探讨了在核静止和有丝分裂之间架起桥梁的过渡态。它为承诺但复制前状态的形成提供了证据。将静止的小鼠瑞士3T3细胞暴露于外部有丝分裂刺激剂(表皮生长因子或过量血清)，同时暴露于同步器，该同步器抑制进入S时相。因此，细胞被刺激合成DNA，但对这种刺激的正常复制反应被阻止。在去除刺激剂后，在不同的时间移除对DNA复制的阻断。实验是为了监测去除外部刺激物后对DNA合成的承诺的衰退。事实证明，这种衰变是一个一级过程。半衰期(在最初致敏的一半细胞中失去对DNA合成的承诺所需的时间)被发现约为5小时。无论是测量总DNA合成还是单个复制细胞，结果都是相同的，并且与所使用的外部生长刺激剂或阻滞剂的类型无关。这些结果表明，在有丝分裂途径上，存在一种承诺但复制前的状态。承诺状态似乎代表整个细胞的单位或全局性质，而不是例如某些活性诱导剂分子的临界浓度，因为后者将表现出多次击打衰减动力学而不是实际观察到的单步不稳定性。
This paper explores the transitional states that bridge the gap between nuclear quiescence and mitogenesis. It presents evidence for the formation of a committed but prereplicative state. Quiescent murine Swiss 3T3 cells were exposed to an external mitogenic stimulant (epidermal growth factor or excess serum) and simultaneously to a synchronizer which inhibits entry into the S phase. Thus, the cells were stimulated to synthesize DNA, but the normal replicative response to this stimulus was blocked. The block to DNA replication was removed at varying times after removal of the stimulant. Experiments were done to monitor the decay of commitment to DNA synthesis after removal of the external stimulant. This decay turned out to be a first-order process. The half-life (time required for loss of the commitment to DNA synthesis in half of the initially sensitized cells) was found to be approximately 5 hr. The same result was found whether total DNA synthesis or individually replicating cells were measured and was independent of the type of external growth stimulant or blocker used. These results point to the existence, on the mitogenic pathway, of a committed but prereplicative state. The committed state appears to represent a unit or global property of the whole cell rather than, for example, a critical concentration of some active inducer molecule because the latter would display multi-hit decay kinetics rather than the single-step lability actually observed.