Opposing effects of pericentrin and microcephalin on the pericentriolar material regulate CHK1 activation in the DNA damage response

Abstract

Genotoxic stresses lead to centrosome amplification, a frequently-observed feature in cancer that may contribute to genome instability and to tumour cell invasion. Here we have explored how the centrosome controls DNA damage responses. For most of the cell cycle, centrosomes consist of two centrioles embedded in the proteinaceous pericentriolar material (PCM). Recent data indicate that the PCM is not an amorphous assembly of proteins, but actually a highly organised scaffold around the centrioles. The large coiled-coil protein, pericentrin, participates in PCM assembly and has been implicated in the control of DNA damage responses (DDRs) through its interactions with checkpoint kinase 1 (CHK1) and microcephalin (MCPH1). CHK1 is required for DNA damage-induced centrosome amplification, whereas MCPH1 deficiency greatly increases the amplification seen after DNA damage. We found that the PCM showed a marked expansion in volume and a noticeable change in higher-order organisation after ionising radiation treatment. PCM expansion was dependent on CHK1 kinase activity and was potentiated by MCPH1 deficiency. Furthermore, pericentrin deficiency or mutation of a separase cleavage site blocked DNA damage-induced PCM expansion. The extent of nuclear CHK1 activation after DNA damage reflected the level of PCM expansion, with a reduction in pericentrin-deficient or separase cleavage site mutant-expressing cells, and an increase in MCPH1-deficient cells that was suppressed by the loss of pericentrin. Deletion of the nuclear export signal of CHK1 led to its hyperphosphorylation after irradiation and reduced centrosome amplification. Deletion of the nuclear localisation signal led to low CHK1 activation and low centrosome amplification. From these data, we propose a feedback loop from the PCM to the nuclear DDR in which CHK1 regulates pericentrin-dependent PCM expansion to control its own activation.

Aryl Hydrocarbon Receptor Promotes Liver Polyploidization and Inhibits PI3K, ERK, and Wnt/β-Catenin Signaling

“…Since increased centrosome size appears related to a higher proliferative potential, adult diploid AhR−/− hepatocytes could enlarge their centrosomes to maintain proliferation in the absence of polyploidy. In addition, as PCN regulates mitotic responses in DNA damaged cells ( Antonczak et al., 2016 ), AhR-null hepatocytes could widen their centrosomes to complete cell division under enforced non-polyploid conditions, whereas polyploid AhR wild-type hepatocytes would keep an increased number of smaller centrosomes. Interestingly, lack of the E2F8 transcription factor in mouse liver promotes overexpression of E2F-dependent target genes and enhanced cytokinesis with impaired polyploidization ( Pandit et al., 2012 ).…”

Nuclear roles for cilia-associated proteins

“…The centrin-associated protein pericentrin (PCNT) (OMIM: 605925) has also been implicated in DNA damage repair [96]. Interactions between pericentrin and microcephalin (MCPH1) have been implicated in primordial dwarfism [60], genome instability, and centrosome amplification [2]. …”

Centrosome amplification: a suspect in breast cancer and racial disparities

“…Abnormal amplification of centrosome volume arises from excessive recruitment of PCM, a highly ordered yet dynamic matrix of hundreds of proteins and nucleic acids. PCM size is regulated by centrioles, free cytoplasmic αβ-tubulin, centrobin, kinases like PLK1 and CHK1, and several coiled-coil proteins like pericentrin and CPAP (Antonczak, et al 2015; Conduit, et al 2010; Woodruff, et al 2014). The mechanisms undergirding abnormal amplification of centrosome volume in cancer are still poorly defined, although several stimulators of PCM assembly are overexpressed in cancer (e.g., PLK1 (Degenhardt and Lampkin 2010) and CHK1 (Zhang and Hunter 2014)), cancer cells often harbor supernumerary centrioles (which could then recruit excessive PCM), and the PCM expands following DNA damage (Mullee and Morrison 2015).…”