Expression and Localization of Cdc25B in Mouse Fertilized Eggs

Abstract: The purpose of this study is to elucidate the mechanism of Cdc25B regulating the development of mouse fertilized eggs. Using Western blot to detect the expression of Cdc25B and the phosphorylation status of Cdc2-Tyr15 at various phases in mouse fertilized eggs. The localization of Cdc25B was investigated using fluorescence microscopy at one-cell stage. pEGFP-Cdc25B plasmid was microinjected to mouse fertilized eggs in order to detect location variation of Cdc25B at mitosis. Western blots revealed that Cdc25B was phosphorylated at G₁ and S phase， dephosphorylated at G₂ and M phase. There was strong phosphorylation signal of Cdc2-Tyr15 detected at G₁ and S whereas only slight phosphorylation signal of Cdc2-Tyr15 found at G₂ and no phosphorylation signal of Cdc2-Tyr15 was identified at M phase in mouse fertilized eggs. The subcellular localization of Cdc25B showed that Cdc25B was mainly in cytoplasm and nucleus at G₁， but in cytoplasm cortex at S and G₂ phase. Cdc25B transferred from cytoplasm to nucleus region in part at M phase in mouse fertilized eggs. Our findings identify that Cdc25B exported from nucleus initiates the mitosis by activating M-phase promoting factor in mouse fertilized eggs.

CSTR: 32200.14.cjcb.2007.06.0018