DNA damage-induced centrosome amplification occurs via excessive formation of centriolar satellites

Abstract

Centrosome amplification is a frequent phenomenon in malignancies and may facilitate tumorigenesis by promoting chromosomal instability. On the other hand, a centrosome inactivation checkpoint comprising centrosome amplification leading to elimination of cells by mitotic catastrophe has been described in response to DNA damage by ionizing radiation or cytostatic drugs. So far, the exact nature of DNA damage-induced centrosome amplification, which might be overduplication or fragmentation of existing centrosomes, has been controversial. To solve this controversy, we have established a method to distinguish between these two possibilities using A549 cells expressing photoconvertible CETN2-Dendra2. In response to various DNA-damaging treatments, centrosome amplification but not fragmentation was observed. Moreover, centrosome amplification was preceded by excessive formation of centrin-containing centriolar satellites, which were identified as de novo-generated atypical centrin dots staining positive for centriolar satellite markers but negative or only weakly positive for other established centrosomal markers, and which could be verified as centriolar satellites using immunogold electron microscopy. In line with this notion, disruption of dynein-mediated recruitment of centrosomal proteins via centriolar satellites suppressed centrosome amplification after DNA damage, and excessive formation of centriolar satellites could be inhibited by interference with Chk1, a known mediator of centrosome amplification in response to DNA damage. In conclusion, we provide a model in which a Chk1-mediated DNA damage checkpoint induces excessive formation of centriolar satellites constituting assembly platforms for centrosomal proteins, which subsequently leads to centrosome amplification.

Filia Is an ESC-Specific Regulator of DNA Damage Response and Safeguards Genomic Stability

“…Centrosomes in FK ESCs were abnormal (Figure 1J). This could be a consequence of DNA damage (Bourke et al, 2007; Loffler et al, 2013). To exclude this possibility, we examined the centrosome integrity of FK-Filia, FK-Filia340, FK-S349A and FK-S349D rescue ESCs.…”

Link Between DNA Damage and Centriole Disengagement/Reduplication in Untransformed Human Cells

“…Although the basis for centrosome amplification after DNA damage has been uncertain, recent studies provide evidence for several, and perhaps not mutually exclusive, pathways in transformed cells. Loffler et al (2012) report for human lung adenocarcinoma cells that DNA damage leads to the de novo formation of centrin containing centriolar satellites that may serve as platforms for the assembly of extra centrioles that later organize complete centrosomes. Inanc et al (2010) report that DNA damage leads to the loss of an inhibitory signal that normally blocks centriole reduplication.…”

Centrosomes as signalling centres

“…Indeed, centrosome amplification has been frequently observed in response to DNA damage, for example in ATM-or ATRdeficient human cells [158], or in G2 arrested, Rad51-deficient chicken DT40 cells [159]. The molecular mechanisms underlying centrosome amplification in response to DNA damage remain to be elucidated, but both Chk1 and centriolar satellites have been implicated [158,160]. Moreover, APC/C activity was shown to oscillate, leading to successive rounds of Cdk2 and separase activation in the arrested cells [161].…”