Polo-like kinase 1 (PLK1) and protein phosphatase 6 (PP6) regulate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation in mitosis

Douglas, P., Ye, R., Trinkle‑Mulcahy, L., Neal, J. A., De Wever, V., Morrice, N. A., Meek, K. and Lees‑Miller, S. P. (2014) Polo-like kinase 1 (PLK1) and protein phosphatase 6 (PP6) regulate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation in mitosis. Bioscience Reports, 34(3), pp. 257-271. (doi: 10.1042/BSR20140051)

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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Morrice, Dr Nicholas
• Authors: Douglas, P., Ye, R., Trinkle‑Mulcahy, L., Neal, J. A., De Wever, V., Morrice, N. A., Meek, K., and Lees‑Miller, S. P.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Journal Name: Bioscience Reports
• Publisher: Portland Press Ltd.
• ISSN: 0144-8463
• ISSN (Online): 1573-4935
• Copyright Holders: Copyright © 2014 The Authors
• First Published: First published in Bioscience Reports 34(3):257-271
• Publisher Policy: Reproduced under a Creative Commons License