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Douglas P, Ye R, Trinkle-Mulcahy L, Neal J, De Wever V, Morrice N, Meek K, Lees-Miller S. Polo-like kinase 1 (PLK1) and protein phosphatase 6 (PP6) regulate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation in mitosis. Biosci Rep 2014; 34:e00113. [PMID: 24844881 PMCID: PMC4069685 DOI: 10.1042/bsr20140051] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 04/25/2014] [Accepted: 05/20/2014] [Indexed: 01/28/2023] Open
Abstract
The protein kinase activity of the DNA-PKcs (DNA-dependent protein kinase catalytic subunit) and its autophosphorylation are critical for DBS (DNA double-strand break) repair via NHEJ (non-homologous end-joining). Recent studies have shown that depletion or inactivation of DNA-PKcs kinase activity also results in mitotic defects. DNA-PKcs is autophosphorylated on Ser2056, Thr2647 and Thr2609 in mitosis and phosphorylated DNA-PKcs localize to centrosomes, mitotic spindles and the midbody. DNA-PKcs also interacts with PP6 (protein phosphatase 6), and PP6 has been shown to dephosphorylate Aurora A kinase in mitosis. Here we report that DNA-PKcs is phosphorylated on Ser3205 and Thr3950 in mitosis. Phosphorylation of Thr3950 is DNA-PK-dependent, whereas phosphorylation of Ser3205 requires PLK1 (polo-like kinase 1). Moreover, PLK1 phosphorylates DNA-PKcs on Ser3205 in vitro and interacts with DNA-PKcs in mitosis. In addition, PP6 dephosphorylates DNA-PKcs at Ser3205 in mitosis and after IR (ionizing radiation). DNA-PKcs also phosphorylates Chk2 on Thr68 in mitosis and both phosphorylation of Chk2 and autophosphorylation of DNA-PKcs in mitosis occur in the apparent absence of Ku and DNA damage. Our findings provide mechanistic insight into the roles of DNA-PKcs and PP6 in mitosis and suggest that DNA-PKcs' role in mitosis may be mechanistically distinct from its well-established role in NHEJ.
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Key Words
- dna-dependent protein kinase
- midbody
- mitosis
- polo-like protein kinase 1
- protein phosphatase 6
- atm, ataxia telangiectasia mutated
- chk2, checkpoint kinase 2
- dmem, dulbecco’s modified eagle’s medium
- dna-pkcs, dna-dependent protein kinase catalytic subunit
- dapi, 4′,6-diamidino-2-phenylindole
- dsb, dna double-strand break
- fha, forkhead associated
- gfp, green fluorescent protein
- ir, ionizing radiation
- mem, minimum essential medium alpha
- nhej, non-homologous end-joining
- pipes, 1,4-piperazinediethanesulfonic acid
- plk1, polo-like kinase-1
- pp6, protein phosphatase 6
- sirna, small interfering rna
- tpx2, targeting protein for xklp2
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Affiliation(s)
- Pauline Douglas
- *Departments of Biochemistry & Molecular Biology and Oncology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - Ruiqiong Ye
- *Departments of Biochemistry & Molecular Biology and Oncology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - Laura Trinkle-Mulcahy
- †Department of Cellular & Molecular Medicine and Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada, K1H 8M5
| | - Jessica A. Neal
- ‡Departments of Pathobiology & Diagnostic Investigation, and Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, U.S.A
| | - Veerle De Wever
- §Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 4N1
| | - Nick A. Morrice
- ∥Beatson Institute for Cancer Research, Glasgow G61 1BD Scotland, U.K
| | - Katheryn Meek
- ‡Departments of Pathobiology & Diagnostic Investigation, and Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, U.S.A
| | - Susan P. Lees-Miller
- *Departments of Biochemistry & Molecular Biology and Oncology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
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