Cytokinesis failure occurs in Fanconi anemia pathway–deficient murine and human bone marrow hematopoietic cells

Abstract

Fanconi anemia (FA) is a genomic instability disorder characterized by bone marrow failure and cancer predisposition. FA is caused by mutations in any one of several genes that encode proteins cooperating in a repair pathway and is required for cellular resistance to DNA crosslinking agents. Recent studies suggest that the FA pathway may also play a role in mitosis, since FANCD2 and FANCI, the 2 key FA proteins, are localized to the extremities of ultrafine DNA bridges (UFBs), which link sister chromatids during cell division. However, whether FA proteins regulate cell division remains unclear. Here we have shown that FA pathway-deficient cells display an increased number of UFBs compared with FA pathway-proficient cells. The UFBs were coated by BLM (the RecQ helicase mutated in Bloom syndrome) in early mitosis. In contrast, the FA protein FANCM was recruited to the UFBs at a later stage. The increased number of bridges in FA pathway-deficient cells correlated with a higher rate of cytokinesis failure resulting in binucleated cells. Binucleated cells were also detectable in primary murine FA pathway-deficient hematopoietic stem cells (HSCs) and bone marrow stromal cells from human patients with FA. Based on these observations, we suggest that cytokinesis failure followed by apoptosis may contribute to bone marrow failure in patients with FA.

ERCC1 function in nuclear excision and interstrand crosslink repair pathways is mediated exclusively by the ERCC1-202 isoform

“…27,28 Third, the presence of anaphase bridges during mitosis in FA-deficient pathway cells can lead to cytokinesis failure and aneuploidy. 26 Finally, recent work has demonstrated a functional interplay between ERCC1/XPF and FANCD2 on mitotic chromosomes, both proteins interacting together in order to protect common fragile sites and avoid anaphase bridges and subsequent chromosomal instability. 33 Of note, as interwined chromatids may lead to gross chromosome loss or rearrangement, we investigated whether ERCC1-deficient A549 cells displayed genomic instability by performing CGH and cytogenetic analysis of the ERCC1-WT cell line and the ERCC1-deficient clones.…”

“…26 The repair of these lesions relies on the FA pathway and on homology-directed repair, 2 processes likely to be affected by ERCC1 disruption. 27,28 Indeed, ERCC1 participates to the FA-mediated repair of ICLs and was shown to interact with FANCG.…”

Genetic Basis of Inherited Bone Marrow Failure Syndromes

“…BLM participates in the resolution of these bridges during mitosis and persistent DNA bridges may lead to micronucleation. (Chan, Palmai-Pallag et al 2009) Vinciguerra et al (Vinciguerra, Godinho et al 2010) demonstrated abnormally high number of ultrafine DNA bridges in cellular models of FA, which was correlated with a higher rate of cytokinesis failure and formation of binucleated cells.…”

A new class of ultrafine anaphase bridges generated by homologous recombination

“…However, the exact role of RIF1 in processing UFBs remains unclear. Other factors, such as TOPBP1 [63,64] and FANCM [65] also localize to certain types of UFBs (TOPBP1 on C-UFBs and FANCM on FS-UFBs).

10.1080/15384101.2018.1515555-F0002Figure 2.HR-UFBs arise in resolvase-deficient cells. U2OS cells were treated with siRNA against MUS81 and GEN1 to inactivate the SMX and GEN1 Holliday junction resolvases.

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