title: NEK11 regulates CDC25A degradation and the IR-induced G2/M checkpoint.
abstract: DNA damage-induced cell-cycle checkpoints have a critical role in maintaining genomic stability. A key target of the checkpoints is the CDC25A (cell division cycle 25 homologue A) phosphatase, which is essential for the activation of cyclin-dependent kinases and cell-cycle progression. To identify new genes involved in the G2/M checkpoint we performed a large-scale short hairpin RNA (shRNA) library screen. We show that NIMA (never in mitosis gene A)-related kinase 11 (NEK11) is required for DNA damage-induced G2/M arrest. Depletion of NEK11 prevents proteasome-dependent degradation of CDC25A, both in unperturbed and DNA-damaged cells. We show that NEK11 directly phosphorylates CDC25A on residues whose phosphorylation is required for beta-TrCP (beta-transducin repeat-containing protein)-mediated polyubiquitylation and degradation of CDC25A. Furthermore, we demonstrate that CHK1 (checkpoint kinase 1) directly activates NEK11 by phosphorylating it on Ser 273, indicating that CHK1 and NEK11 operate in a single pathway that controls proteolysis of CDC25A. Taken together, these results demonstrate that NEK11 is an important component of the pathway enforcing the G2/M checkpoint, suggesting that genetic mutations in NEK11 may contribute to the development of human cancer.
authors.affiliation: Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, 20135, Milan, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Melixetian
authors.forename: Ditte Kjaersgaard
authors.initials: DK
authors.lastname: Klein
authors.forename: Claus Storgaard
authors.initials: CS
authors.lastname: Sørensen
authors.forename: Kristian
authors.initials: K
authors.lastname: Helin
mesh_terms: D000595:Amino Acid Sequence; D000071877:Checkpoint Kinase 1; D004789:Enzyme Activation; D016195:G2 Phase / Q000235:genetics / Q000528:radiation effects*; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008938:Mitosis; D008969:Molecular Sequence Data; D000072379:NIMA-Related Kinases; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D011839:Radiation, Ionizing; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D014162:Transfection; D054875:Ubiquitination; D044844:beta-Transducin Repeat-Containing Proteins / Q000235:genetics / Q000378:metabolism; D020687:cdc25 Phosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000071877:Checkpoint Kinase 1; D000072379:NIMA-Related Kinases; D011494:Protein Kinases; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D012694:Serine; D044844:beta-Transducin Repeat-Containing Proteins; D020687:cdc25 Phosphatases; C000605867:CHEK1 protein, human; C469355:NEK11 protein, human