title: Greatwall and Polo-like kinase 1 coordinate to promote checkpoint recovery.
abstract: Checkpoint recovery upon completion of DNA repair allows the cell to return to normal cell cycle progression and is thus a crucial process that determines cell fate after DNA damage. We previously studied this process in Xenopus egg extracts and established Greatwall (Gwl) as an important regulator. Here we show that preactivated Gwl kinase can promote checkpoint recovery independently of cyclin-dependent kinase 1 (Cdk1) or Plx1 (Xenopus polo-like kinase 1), whereas depletion of Gwl from extracts exhibits no synergy with that of Plx1 in delaying checkpoint recovery, suggesting a distinct but related relationship between Gwl and Plx1. In further revealing their functional relationship, we found mutual dependence for activation of Gwl and Plx1 during checkpoint recovery, as well as their direct association. We characterized the protein association in detail and recapitulated it in vitro with purified proteins, which suggests direct interaction. Interestingly, Gwl interaction with Plx1 and its phosphorylation by Plx1 both increase at the stage of checkpoint recovery. More importantly, Plx1-mediated phosphorylation renders Gwl more efficient in promoting checkpoint recovery, suggesting a functional involvement of such regulation in the recovery process. Finally, we report an indirect regulatory mechanism involving Aurora A that may account for Gwl-dependent regulation of Plx1 during checkpoint recovery. Our results thus reveal novel mechanisms underlying the involvement of Gwl in checkpoint recovery, in particular, its functional relationship with Plx1, a well characterized regulator of checkpoint recovery. Coordinated interplays between Plx1 and Gwl are required for reactivation of these kinases from the G(2)/M DNA damage checkpoint and efficient checkpoint recovery.
authors.affiliation: Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska 68583. Electronic address: Aimin.Peng@UNMC.edu.
authors.forename: Aimin
authors.initials: A
authors.lastname: Peng
authors.affiliation: Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska 68583.
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska 68583.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Fisher
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D002474:Cell-Free System / Q000378:metabolism; D004249:DNA Damage / Q000502:physiology*; D016195:G2 Phase / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis; D000097869:Polo-Like Kinase 1
chemical_list: D016203:CDC2 Protein Kinase; D018797:Cell Cycle Proteins; D017346:Protein Serine-Threonine Kinases; D029867:Xenopus Proteins; C544010:MASTL protein, Xenopus; C101085:Plk1 protein, Xenopus; D000097869:Polo-Like Kinase 1