Takagi Sawada M, Kyozuka K, Morinaga C, Izumi K, Sawada H
Bioscience and Chemistry Division, Hokkaido National Industrial Research Institute, MITI, Toyohira-ku, Sapporo, Japan.
Biochem Biophys Res Commun. 1997 Jul 9;236(1):40-3. doi: 10.1006/bbrc.1997.6900.
Starfish oocyte maturation was blocked by the addition of 100 microM MG115, a potent proteasome inhibitor, whereas no inhibition was observed by membrane permeable cysteine protease inhibitor, E-64-d. The inhibition by MG115 was diminished by adding at a time corresponding to the half time required for germinal vesicle breakdown. Potent inhibition of germinal vesicle breakdown was also observed by microinjection of anti-proteasome-a-subunit antibodies. The antibody-injected oocytes failed to activate pre-maturation promoting factor (pre-MPF), since the dephosphorylation of phospho-Tyr15 in cdc2 kinase was not observed even in the presence of 1-methyadenine, a maturation-inducing hormone. These results indicate that the proteasome triggers the activation of pre-MPF via the dephosphorylation of cdc2 kinase in the signal transduction pathway in response to the hormonal stimulus during starfish oocyte maturation.
添加100微摩尔的MG115（一种有效的蛋白酶体抑制剂）可阻断海星卵母细胞的成熟，而膜通透性半胱氨酸蛋白酶抑制剂E-64-d未观察到抑制作用。在与生发泡破裂所需半衰期相对应的时间添加时，MG115的抑制作用减弱。通过显微注射抗蛋白酶体α亚基抗体也观察到对生发泡破裂的有效抑制。注射抗体的卵母细胞未能激活早熟促进因子（pre-MPF），因为即使在存在成熟诱导激素1-甲基腺嘌呤的情况下，也未观察到cdc2激酶中磷酸化酪氨酸15的去磷酸化。这些结果表明，在海星卵母细胞成熟过程中，蛋白酶体在信号转导途径中通过cdc2激酶的去磷酸化触发pre-MPF的激活，以响应激素刺激。
