title: CDC25B acts as a potential target of PRKACA in fertilized mouse eggs.
abstract: Protein kinase A (PRKACA) has been documented as a pivotal regulator in meiosis and mitosis arrest. Although our previous work has established that PRKACA regulates cell cycle progression of mouse fertilized eggs by inhibiting M-phase promoting factor (MPF), little is known about the intermediate factor between PRKACA and MPF in the mitotic cell cycle. In this study, we investigated the role of the PRKACA/CDC25B pathway on the early development of mouse fertilized eggs. Overexpression of unphosphorylatable CDC25B mutant (Cdc25b-S321A or Cdc25b-S229A/S321A) rapidly caused G2-phase eggs to enter mitosis. Microinjection of either Cdc25b-WT or Cdc25b-S229A mRNA also promoted G2/M transition, but much less efficiently than Cdc25b-S321A and Cdc25b-S229A/S321A. Moreover, mouse fertilized eggs overrode the G2 arrest by microinjection of either Cdc25b-S321A or Cdc25b-S229A/S321A mRNA, which efficiently resulted in MPF activation by directly dephosphorylating CDC2A-Tyr15, despite culture under conditions that maintained exogenous dibutyryl cAMP. Using a highly specific antibody against phospho-Ser321 of CDC25B in Western blotting, we showed that CDC25B-Ser321 was phosphorylated at the G1 and S phases, whereas Ser321 was dephosphorylated at the G2 and M phases in vivo. Our findings identify CDC25B as a potential target of PRKACA and show that PRKACA regulates G2/M transition by phosphorylating CDC25B-Ser321 but not CDC25B-Ser229 on the first mitotic division of mouse fertilized eggs.
authors.affiliation: Department of Physiology, China Medical University, Shenyang 110001, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Cui
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhao
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhang
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zong
authors.forename: Chen
authors.initials: C
authors.lastname: Feng
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Deng
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Xu
authors.forename: Bingzhi
authors.initials: B
authors.lastname: Yu
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits / Q000378:metabolism*; D047108:Embryonic Development; D005260:Female; D016195:G2 Phase; D016200:Maturation-Promoting Factor / Q000378:metabolism; D000090204:Mesothelin; D051379:Mice; D008845:Microinjections; D008938:Mitosis; D010766:Phosphorylation; D012333:RNA, Messenger / Q000008:administration & dosage; D015053:Zygote / Q000254:growth & development / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000378:metabolism*
chemical_list: C000715528:Msln protein, mouse; D012333:RNA, Messenger; D003994:Bucladesine; D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits; C517758:Prkaca protein, mouse; D016200:Maturation-Promoting Factor; C517006:Cdc25b protein, mouse; D020687:cdc25 Phosphatases; D000090204:Mesothelin