DNA‐PKcs Associates With PLK1 and Is Involved in Proper Chromosome Segregation and Cytokinesis

Abstract

Accurate mitotic regulation is as important as intrinsic DNA repair for maintaining genomic stability. It is believed that these two cellular mechanisms are interconnected with DNA damage. DNA-PKcs is a critical component of the non-homologous end-joining pathway of DNA double-stranded break repair, and it was recently discovered to be involved in mitotic processing. However, the underlying mechanism of DNA-PKcs action in mitotic control is unknown. Here, we demonstrated that depletion of DNA-PKcs led to the dysregulation of mitotic progression in response to DNA damage, which eventually resulted in multiple failures, including failure to segregate sister chromatids and failure to complete cytokinesis, with daughter cells becoming fused again. The depletion of DNA-PKcs resulted in a notable failure of cytokinesis, with a high incidence of multinucleated cells. There were also cytoplasmic bridges containing DNA that continuously connected the daughter cells after DNA damage was induced. Phosphorylated DNA-PKcs (T2609) colocalizes with PLK1 throughout mitosis, including at the centrosomes from prophase to anaphase and at the kinetochores from prometaphase to metaphase, with accumulation at the midbody during cytokinesis. Importantly, DNA-PKcs was found to associate with PLK1 in the mitotic phase, and the depletion of DNA-PKcs resulted in the overexpression of PLK1 due to increased protein stability. However, deficiency in DNA-PKcs attenuated the recruitment of phosphorylated PLK1 to the midbody but not to the kinetochores and centrosomes. Our results demonstrate the functional association of DNA-PKcs with PLK1, especially in chromosomal segregation and cytokinesis control.

The DNA-dependent protein kinase: A multifunctional protein kinase with roles in DNA double strand break repair and mitosis

“…Consistent with a role in mitosis, DNA-PKcs interacts with PLK1 (Douglas et al, 2014; Huang et al, 2014) and phosphorylates checkpoint kinase 2 (Chk2) on T68 in mitosis (Douglas et al, 2014; Tu et al, 2013) (Figure 4A). This is contrast to phosphorylation of T68 of Chk2 in response to DNA damage, which is ATM-dependent (Ahn et al, 2000; Matsuoka et al, 1998).…”

PIG3 promotes NSCLC cell mitotic progression and is associated with poor prognosis of NSCLC patients

“…We and others have identified a novel role of DNA-PKcs in maintaining normal spindle formation or centrosomes stability [21, 31–33]. In addition, DNA-PKcs contributes to mitotic entry and cytokinesis progression by activating Plk1 in a temporal and spatial fashion [34, 35]. During mitosis, the Chk2-Brca1 signaling cascade is downstream of DNA-PKcs and has an effect on mitotic microtubule assembly [21].…”

JIP4 is a PLK1 binding protein that regulates p38MAPK activity in G2 phase

“…DNA-PK has been shown to be phosphorylated by and bind PLK1 in mitosis [24]. PRKDC/DNA-PKcs, the catalytic subunit of DNA-PK is phosphorylated and binds PLK1, and PRKDC/ DNA-PKcs forms a complex with Protein Phosphatase 6 (PPP6)/PPP6R2 [24,43]. ANKRD28/PP6-ARS-A binds to PPP6 complex through a SAPS domain PPP6R regulatory domains [44], thus these latter proteins are likely to be part of the DNA-PK complex.…”