Matten W T, Copeland T D, Ahn N G, Vande Woude G F
ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702, USA.
Dev Biol. 1996 Nov 1;179(2):485-92. doi: 10.1006/dbio.1996.0277.
Mos is a serine-threonine protein kinase and a key regulator of meiosis. One function of Xenopus Mos is to activate mitogen-activated protein kinase (MAPK) through direct phosphorylation and activation of MAPK kinase (MAPKK). All three members of this signal cascade can individually induce hormone-independent reentry of oocytes into meiosis I. However, their inducing efficiency is reduced in the absence of protein synthesis. Here we show that de novo Mos synthesis is required for induction of meiosis I by active MAPKK or Mos-MAPK coinjection. In addition, MAPK efficiently phosphorylates Mos at Ser-3 in vitro. These results suggest that a positive feedback loop exists between MAPK and Mos during oocyte maturation. De novo synthesis of Mos, and other proteins, is required for progression from meiosis I to the metaphase arrest at meiosis II; therefore, one function of MAPK during normal Xenopus oocyte maturation might be to stimulate the synthesis or accumulation of Mos that is required for the completion of meiosis.
Mos是一种丝氨酸 - 苏氨酸蛋白激酶，也是减数分裂的关键调节因子。非洲爪蟾Mos的一个功能是通过直接磷酸化和激活丝裂原活化蛋白激酶激酶（MAPKK）来激活丝裂原活化蛋白激酶（MAPK）。该信号级联的所有三个成员都可以单独诱导卵母细胞在无激素的情况下重新进入减数分裂I。然而，在缺乏蛋白质合成的情况下，它们的诱导效率会降低。在这里我们表明，从头合成Mos是由活性MAPKK或共注射Mos - MAPK诱导减数分裂I所必需的。此外，MAPK在体外能有效地将Mos的丝氨酸 - 3磷酸化。这些结果表明，在卵母细胞成熟过程中，MAPK和Mos之间存在正反馈回路。从头合成Mos和其他蛋白质是从减数分裂I进展到减数分裂II中期停滞所必需的；因此，在正常非洲爪蟾卵母细胞成熟过程中，MAPK的一个功能可能是刺激完成减数分裂所需的Mos的合成或积累。
