Molecular system ensuring genomic inheritance through successive generations

在细胞周期控制和细胞核形成的基础上，研究了确保基因组遗传的分子机制。我们的研究结果总结如下。减数分裂细胞周期进程：海星卵母细胞中导致减数分裂再起始的几乎完整的信号通路已被发现由推定的成熟诱导激素受体，1-MeAde / Gβ1γ2 / I-β型pi3激酶/ PDK1和推定的PDK2 / Akt (PKB) / Cdc2-cyclin B / Plk1组成。在减数分裂再起始后，p90Rsk立即在Mos-MAPK通路下游被激活，积极调节减数分裂I到II的转变和减数分裂II完成后的g1期停止。雄性和雌性原核的形成：利用爪蟾卵母细胞或卵的无细胞提取物来分析这些过程。在受精后，NAP1作为组蛋白H1的分子伴侣参与精子核染色质重塑。在卵母细胞成熟过程中，依赖于输入蛋白α的核输入能力加快，li型核层蛋白新合成，这可能为理解这一时期核形成能力的获得提供线索。受精后s期的开始：在未受精的海星成熟卵中，mcm已经装载到雌性原核的染色质上，但Cdc45的装载允许DNA聚合酶a装载到DNA上，在下游的Mos-MAPK-p90Rsk途径中被阻止。p90Rsk活性的消除足以启动DNA复制，从而为回答生物学中受精如何启动s期的经典问题提供了线索。

Molecular mechanisms that ensure genomic inheritance through successive generations have been studied, based on the cell cycle control and the nuclear formation. Our findings are summarized below.1. Meiotic cell cycle progression : Almost complete signaling pathway that leads to meiotic reinitiation in starfish oocytes has been revealed to be composed of the putative receptor for maturation-inducing hormone, 1-MeAde / Gβ1γ2 / I-β type PI3-kinase / PDK1 and putative PDK2 / Akt (PKB) / Cdc2-cyclin B / Plk1. After meiotic reinitiation, p90Rsk is activated immediately downstream of the Mos-MAPK pathway to regulate positively both meiosis I to II transition and G1-phase arrest after completion of meiosis II.2. Formation of male and female pronuclei : Cell-free extracts derived from Xenopus oocytes or eggs were utilized to analyze these processes. Upon fertiliztion, NAP1 functions as a molecular chaperone for histone H1 at the chromatin remodeling in sperm nuclei. During oocyte maturation, the ability of nuclear import that depends on importin α is accelerated, and the LI-type nuclear lamin is newly synthesized, possibly providing a clue to understand how the ability for nuclear formation is acquired in this period.3. Initiation of S-phase upon fertilization : In unfertilized mature eggs of starfish, MCMs are already loaded onto chromatin in female pronucleus, but the loading of Cdc45, which allows the loading of DNA polymerase a to DNA, is prevented downstream of the Mos-MAPK-p90Rsk pathway. Abolishment of p90Rsk activity is sufficient for initiation of DNA replication, thus providing a clue to answer the classic question in biology how fertilization initiates S-phase.