title: Ser149 is another potential PKA phosphorylation target of Cdc25B in G2/M transition of fertilized mouse eggs.
abstract: It is well documented that protein kinase A (PKA) acts as a negative regulator of M phase promoting factor (MPF) by phosphorylating cell division cycle 25 homolog B (Cdc25B) in mammals. However, the molecular mechanism remains unclear. In this study, we identified PKA phosphorylation sites in vitro by LC-MS/MS analysis, including Ser(149), Ser(229), and Ser(321) of Cdc25B, and explored the role of Ser(149) in G(2)/M transition of fertilized mouse eggs. The results showed that the overexpressed Cdc25B-S149A mutant initiated efficient MPF activation by direct dephosphorylation of Cdc2-Tyr(15), resulting in triggering mitosis prior to Cdc25B-WT. Conversely, overexpression of the phosphomimic Cdc25B-S149D mutant showed no significant difference in comparison with the control groups. Furthermore, we found that Cdc25B-Ser(149) was phosphorylated at G(1) and S phases, whereas dephosphorylated at G(2) and M phases, and the phosphorylation of Cdc25B-Ser(149) was modulated by PKA in vivo. In addition, we examined endogenous and exogenous Cdc25B, which were expressed mostly in the cytoplasm at the G(1) and S phases and translocated to the nucleus at the G(2) phase. Collectively, our findings provide evidence that Ser(149) may be another potential PKA phosphorylation target of Cdc25B in G(2)/M transition of fertilized mouse eggs and Cdc25B as a direct downstream substrate of PKA in mammals, which plays important roles in the regulation of early development of mouse embryos.
authors.affiliation: Institute of Pathology and Pathopysiology, China Medical University, Shenyang, Liaoning Province 110001, China.
authors.forename: Jianying
authors.initials: J
authors.lastname: Xiao
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.forename: Junjie
authors.initials: J
authors.lastname: Hou
authors.forename: Cheng
authors.initials: C
authors.lastname: Cui
authors.forename: Didi
authors.initials: D
authors.lastname: Wu
authors.forename: Huiyu
authors.initials: H
authors.lastname: Fan
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Sun
authors.forename: Jun
authors.initials: J
authors.lastname: Meng
authors.forename: Fuquan
authors.initials: F
authors.lastname: Yang
authors.forename: Enhua
authors.initials: E
authors.lastname: Wang
authors.forename: Bingzhi
authors.initials: B
authors.lastname: Yu
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D019943:Amino Acid Substitution; D000818:Animals; D002455:Cell Division / Q000502:physiology*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000201:enzymology; D005260:Female; D016195:G2 Phase / Q000502:physiology*; D008297:Male; D016200:Maturation-Promoting Factor / Q000235:genetics / Q000378:metabolism; D000090204:Mesothelin; D051379:Mice; D020125:Mutation, Missense; D010766:Phosphorylation / Q000235:genetics; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015053:Zygote / Q000166:cytology / Q000201:enzymology*; D020687:cdc25 Phosphatases / Q000235:genetics / Q000378:metabolism*
chemical_list: C000715528:Msln protein, mouse; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases; D016200:Maturation-Promoting Factor; C517006:Cdc25b protein, mouse; D020687:cdc25 Phosphatases; D000090204:Mesothelin