Ecroyd Heath, Jones Russell C, Aitken R John
Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia.
Biol Reprod. 2003 Dec;69(6):1801-7. doi: 10.1095/biolreprod.103.017350. Epub 2003 Jul 30.
The process of sperm capacitation is correlated with activation of a signal transduction pathway leading to protein tyrosine phosphorylation. Whereas phosphotyrosine expression is an essential prerequisite for fertilization, the proteins that are phosphorylated during capacitation have not yet been identified. In the present study, we observed that a major target of this signaling pathway is the molecular chaperone protein, heat shock protein (HSP)-86, a member of the HSP-90 family of HSPs. We used cross-immunoprecipitation experiments to confirm the tyrosine phosphorylation of HSP-86, a process that is not inhibited by the ansamycin antibiotic, geldanamycin. The general significance of these findings was confirmed by studies in which HSP-90 was also found to be tyrosine phosphorylated in human and rat spermatozoa when incubated under conditions that support capacitation. To our knowledge, these results represent the first report of a protein that undergoes tyrosine phosphorylation during mouse sperm capacitation and the first study implicating molecular chaperones in the processes by which mammalian spermatozoa gain the ability to fertilize the oocyte.
精子获能过程与导致蛋白质酪氨酸磷酸化的信号转导通路的激活相关。虽然磷酸酪氨酸表达是受精的必要前提，但在获能过程中被磷酸化的蛋白质尚未被鉴定出来。在本研究中，我们观察到该信号通路的一个主要靶点是分子伴侣蛋白热休克蛋白（HSP）-86，它是热休克蛋白HSP-90家族的一员。我们使用交叉免疫沉淀实验来证实HSP-86的酪氨酸磷酸化，这一过程不受安莎霉素抗生素格尔德霉素的抑制。通过研究也证实了这些发现的普遍意义，即在支持获能的条件下孵育时，在人类和大鼠精子中也发现HSP-90发生了酪氨酸磷酸化。据我们所知，这些结果代表了关于在小鼠精子获能过程中发生酪氨酸磷酸化的蛋白质的首次报道，也是关于分子伴侣参与哺乳动物精子获得使卵母细胞受精能力过程的首次研究。
