title: GADD45-induced cell cycle G2-M arrest associates with altered subcellular distribution of cyclin B1 and is independent of p38 kinase activity.
abstract: In response to DNA damage, the cell cycle checkpoint is an important biological event in maintaining genomic fidelity. Gadd45, a p53-regulated and DNA damage inducible protein, has recently been demonstrated to play a role in the G2-M checkpoint in response to DNA damage. In the current study, we further investigated the biochemical mechanism(s) involved in the GADD45-activated cell cycle G2-M arrest. Using the tetracycline-controlled system (tet-off), we established GADD45-inducible lines in HCT116 (wild-type p53) and Hela (inactivated p53 status) cells. Following inducible expression of the Gadd45 protein, cell growth was strongly suppressed in both HCT116 and Hela cells. Interestingly, HCT116 cells revealed a significant G2-M arrest but Hela cells failed to arrest at the G2-M phases, indicating that the GADD45-activated G2-M arrest requires normal p53 function. The GADD45-induced G2-M arrest was observed independent of p38 kinase activity. Importantly, induction of Gadd45 protein resulted in a reduction of nuclear cyclin B1 protein, whose nuclear localization is critical for the completion of G2-M transition. The reduced nuclear cyclin B1 levels correlated with inhibition of Cdc2/cyclin B1 kinase activity. Additionally, overexpression of cyclin B1 substantially abrogated the GADD45-induced cell growth suppression. Therefore, GADD45 inhibition of Cdc2 kinase activity through alteration of cyclin B1 subcellular localization may be an essential step in the GADD45-induced cell cycle G2-M arrest and growth suppression.
authors.affiliation: Department of Radiation Oncology, Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, USA.
authors.forename: Shunqian
authors.initials: S
authors.lastname: Jin
authors.forename: Tong
authors.initials: T
authors.lastname: Tong
authors.forename: Wenhong
authors.initials: W
authors.lastname: Fan
authors.forename: Feiyue
authors.initials: F
authors.lastname: Fan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Antinore
authors.forename: Xiaocheng
authors.initials: X
authors.lastname: Zhu
authors.forename: Lucia
authors.initials: L
authors.lastname: Mazzacurati
authors.forename: Xianxing
authors.initials: X
authors.lastname: Li
authors.forename: Kimberly L
authors.initials: KL
authors.lastname: Petrik
authors.forename: Baskaran
authors.initials: B
authors.lastname: Rajasekaran
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.forename: Qimin
authors.initials: Q
authors.lastname: Zhan
mesh_terms: D000071877:Checkpoint Kinase 1; D019926:Cyclin B / Q000378:metabolism*; D056744:Cyclin B1; D016195:G2 Phase / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008938:Mitosis / Q000235:genetics*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D013347:Subcellular Fractions / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases; D000097642:GADD45 Proteins
chemical_list: D000071877:Checkpoint Kinase 1; D019926:Cyclin B; D056744:Cyclin B1; D047908:Intracellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases; D011494:Protein Kinases; D011506:Proteins; D016159:Tumor Suppressor Protein p53; D048051:p38 Mitogen-Activated Protein Kinases; D000097642:GADD45 Proteins; C534699:CCNB1 protein, human