Micronuclei-based model system reveals functional consequences of chromothripsis in human cells

Abstract

Cancer cells often harbor chromosomes in abnormal numbers and with aberrant structure. The consequences of these chromosomal aberrations are difficult to study in cancer, and therefore several model systems have been developed in recent years. We show that human cells with extra chromosome engineered via microcell-mediated chromosome transfer often gain massive chromosomal rearrangements. The rearrangements arose by chromosome shattering and rejoining as well as by replication-dependent mechanisms. We show that the isolated micronuclei lack functional lamin B1 and become prone to envelope rupture, which leads to DNA damage and aberrant replication. The presence of functional lamin B1 partly correlates with micronuclei size, suggesting that the proper assembly of nuclear envelope might be sensitive to membrane curvature. The chromosomal rearrangements in trisomic cells provide growth advantage compared to cells without rearrangements. Our model system enables to study mechanisms of massive chromosomal rearrangements of any chromosome and their consequences in human cells.

Chromothripsis as an on-target consequence of CRISPR-Cas9 genome editing

“…Moreover, in 11 of the 13 samples with chromothripsis, haplotype-resolved DNA copy number analysis demonstrated that the micronuclear chromosome showed little detectable replication, again confirming our prior work (31). Together with other recent work examining clonal cell populations after the induction of micronuclei, it is now clear that these structures generate chromothripsis at remarkably high rates (34, 43, 45).…”

Small but strong: Mutational and functional landscapes of micronuclei in cancer genomes

“…5,24 Actually, it has suggested that eccDNA production is also an immediate mutational outcome of micronucleation. 82 Second, it has found that copy numbers are increased at multiple loci in the micronucleated chromosomes, 24,38 suggesting chromoanasynthesis ( Table 1) occurs downstream of micronucleation.…”

“…While Zhang et al 82 and Umbreit et al 32 directly investigated the immediate mutational outcomes of micronucleation by SCS, the other studies performed WGS [23][24][25]30,38 and CNV analsyis 11 Under this circumstance, the micronucleated cells will be out-competed by their nonmicronucleated counterparts rapidly. (B) On the other hand, frequent micronucleation events can also occur in cells with a functional p53 response.…”

“…33,37 Micronuclei of small sizes are more likely to be deficient for lamin-B than those of large ones. 38,39 Micronuclei in p53-deficient cells more often have lamin-B defects than those in p53-wildtype cells. 39 mNE also manifests heterogeneity in the presence or absence of lamin-A/C.…”

Chromothripsis and Duplications as Underappreciated Genomic Gremlins

“…For instance, in micronuclei the amount of lamin B1 is strongly diminished, nuclear pore complex proteins are not detectable, and they lack proteasomes [Hatch et al, 2013;Liu et al, 2018;Maass et al, 2018]. In larger micronuclei, some lamin B1 is present, however [Kneissig et al, 2019]. On the other hand, micronuclei retain the BLM-encoded 3′-> 5′ exonuclease and show significant increases in emerin [Yanki-wski et al, 2000;Maass et al, 2018].…”