scholarly journals EXD2 and WRN exonucleases are required for interstrand crosslink repair in Drosophila

2018 ◽  
Author(s):  
Pratima Chennuri ◽  
Lynne S. Cox ◽  
Robert D. C. Saunders
Keyword(s):  
Genomic Instability ◽  
Fanconi Anemia ◽  
Werner Syndrome ◽  
Fruit Fly ◽  
Chromosome Breakage ◽  
Cancer Therapies ◽  
Principal Mechanism ◽  
Interstrand Crosslinks ◽  
Interstrand Crosslink ◽  
Interstrand Crosslink Repair

AbstractInterstrand crosslinks (ICLs) present a major threat to genome integrity, preventing both the correct transcription of active chromatin and complete replication of the genome. This is exploited in genotoxic chemotherapy where ICL induction is used to kill highly proliferative cancer cells. Repair of ICLs involves a complex interplay of numerous proteins, including those in the Fanconi anemia (FA) pathway, though alternative and parallel pathways have been postulated. Here, we investigate the role of the 3’-5’ exonuclease, EXD2, and the highly related WRN exonuclease (implicated in premature ageing human Werner syndrome), in repair of interstrand crosslinks in the fruit fly, Drosophila melanogaster. We find that flies mutant for EXD2 (DmEXD2) have elevated rates of genomic instability resulting from chromosome breakage and loss of the resulting acentric fragments, in contrast to WRN exonuclease (DmWRNexo) mutants where excess homologous recombination is the principal mechanism of genomic instability. Most notably, we demonstrate that proliferating larval neuroblasts mutant for either DmWRNexo or DmEXD2 are deficient in repair of DNA interstrand crosslinks caused by diepoxybutane or mitomycin C, strongly suggesting that each nuclease individually plays a role in repair of ICLs in flies. These findings have significant implications not only for understanding the complex process of ICL repair in humans, but also for enhancing cancer therapies that rely on ICL induction, with caveats for cancer therapy in Werner syndrome and Fanconi anemia patients.

scholarly journals Cooperation of the NEIL3 and Fanconi anemia/BRCA pathways in interstrand crosslink repair

2020 ◽  
Vol 48 (6) ◽  
pp. 3014-3028 ◽  
Author(s):  
Niu Li ◽  
Jian Wang ◽  
Susan S Wallace ◽  
Jing Chen ◽  
Jia Zhou ◽  
...  
Keyword(s):  
Fanconi Anemia ◽  
Excision Repair ◽  
Human Cells ◽  
Dependent Manner ◽  
Major Pathway ◽  
Interstrand Crosslinks ◽  
Interstrand Crosslink ◽  
Pathway Activation ◽  
Base Excision ◽  
And Function

Abstract The NEIL3 DNA glycosylase is a base excision repair enzyme that excises bulky base lesions from DNA. Although NEIL3 has been shown to unhook interstrand crosslinks (ICL) in Xenopus extracts, how NEIL3 participants in ICL repair in human cells and its corporation with the canonical Fanconi anemia (FA)/BRCA pathway remain unclear. Here we show that the NEIL3 and the FA/BRCA pathways are non-epistatic in psoralen-ICL repair. The NEIL3 pathway is the major pathway for repairing psoralen-ICL, and the FA/BRCA pathway is only activated when NEIL3 is not present. Mechanistically, NEIL3 is recruited to psoralen-ICL in a rapid, PARP-dependent manner. Importantly, the NEIL3 pathway repairs psoralen-ICLs without generating double-strand breaks (DSBs), unlike the FA/BRCA pathway. In addition, we found that the RUVBL1/2 complex physically interact with NEIL3 and function within the NEIL3 pathway in psoralen-ICL repair. Moreover, TRAIP is important for the recruitment of NEIL3 but not FANCD2, and knockdown of TRAIP promotes FA/BRCA pathway activation. Interestingly, TRAIP is non-epistatic with both NEIL3 and FA pathways in psoralen-ICL repair, suggesting that TRAIP may function upstream of the two pathways. Taken together, the NEIL3 pathway is the major pathway to repair psoralen-ICL through a unique DSB-free mechanism in human cells.

scholarly journals SLX4IP acts with SLX4 and XPF–ERCC1 to promote interstrand crosslink repair

2019 ◽  
Vol 47 (19) ◽  
pp. 10181-10201 ◽  
Author(s):  
Huimin Zhang ◽  
Zhen Chen ◽  
Yin Ye ◽  
Zu Ye ◽  
Dan Cao ◽  
...  
Keyword(s):  
Bone Marrow Failure ◽  
Dna Lesions ◽  
Developmental Abnormalities ◽  
Interstrand Crosslinks ◽  
Interstrand Crosslink ◽  
Complex Process ◽  
M Phase ◽  
The Stability ◽  
Interstrand Crosslink Repair ◽  
Constitutive Factor

Abstract Interstrand crosslinks (ICLs) are highly toxic DNA lesions that are repaired via a complex process requiring the coordination of several DNA repair pathways. Defects in ICL repair result in Fanconi anemia, which is characterized by bone marrow failure, developmental abnormalities, and a high incidence of malignancies. SLX4, also known as FANCP, acts as a scaffold protein and coordinates multiple endonucleases that unhook ICLs, resolve homologous recombination intermediates, and perhaps remove unhooked ICLs. In this study, we explored the role of SLX4IP, a constitutive factor in the SLX4 complex, in ICL repair. We found that SLX4IP is a novel regulatory factor; its depletion sensitized cells to treatment with ICL-inducing agents and led to accumulation of cells in the G2/M phase. We further discovered that SLX4IP binds to SLX4 and XPF–ERCC1 simultaneously and that disruption of one interaction also disrupts the other. The binding of SLX4IP to both SLX4 and XPF–ERCC1 not only is vital for maintaining the stability of SLX4IP protein, but also promotes the interaction between SLX4 and XPF–ERCC1, especially after DNA damage. Collectively, these results demonstrate a new regulatory role for SLX4IP in maintaining an efficient SLX4–XPF–ERCC1 complex in ICL repair.

scholarly journals On the role of FAN1 in Fanconi anemia

Blood ◽  
2012 ◽  
Vol 120 (1) ◽  
pp. 86-89 ◽  
Author(s):  
Juan P. Trujillo ◽  
Leonardo B. Mina ◽  
Roser Pujol ◽  
Massimo Bogliolo ◽  
Joris Andrieux ◽  
...  
Keyword(s):  
Fanconi Anemia ◽  
Bone Marrow Failure ◽  
Pcr Amplification ◽  
Minor Role ◽  
Interstrand Crosslink ◽  
Genetic Features ◽  
Chromosome Fragility ◽  
A Minor ◽  
Interstrand Crosslink Repair ◽  
Crosslink Repair

Abstract Fanconi anemia (FA) is a rare bone marrow failure disorder with defective DNA interstrand crosslink repair. Still, there are FA patients without mutations in any of the 15 genes individually underlying the disease. A candidate protein for those patients, FA nuclease 1 (FAN1), whose gene is located at chromosome 15q13.3, is recruited to stalled replication forks by binding to monoubiquitinated FANCD2 and is required for interstrand crosslink repair, suggesting that mutation of FAN1 may cause FA. Here we studied clinical, cellular, and genetic features in 4 patients carrying a homozygous 15q13.3 micro-deletion, including FAN1 and 6 additional genes. Biallelic deletion of the entire FAN1 gene was confirmed by failure of 3′- and 5′-PCR amplification. Western blot analysis failed to show FAN1 protein in the patients' cell lines. Chromosome fragility was normal in all 4 FAN1-deficient patients, although their cells showed mild sensitivity to mitomycin C in terms of cell survival and G2 phase arrest, dissimilar in degree to FA cells. Clinically, there were no symptoms pointing the way to FA. Our results suggest that FAN1 has a minor role in interstrand crosslink repair compared with true FA genes and exclude FAN1 as a novel FA gene.

scholarly journals Coordinated Cut and Bypass: Replication of Interstrand Crosslink-Containing DNA

2021 ◽  
Vol 9 ◽  
Author(s):  
Qiuzhen Li ◽  
Kata Dudás ◽  
Gabriella Tick ◽  
Lajos Haracska
Keyword(s):  
Dna Replication ◽  
Fanconi Anemia ◽  
Replication Fork ◽  
Defense Mechanism ◽  
Genome Instability ◽  
Dna Lesions ◽  
Fanconi Anemia Pathway ◽  
Interstrand Crosslinks ◽  
Dna Lesion ◽  
Interstrand Crosslink

DNA interstrand crosslinks (ICLs) are covalently bound DNA lesions, which are commonly induced by chemotherapeutic drugs, such as cisplatin and mitomycin C or endogenous byproducts of metabolic processes. This type of DNA lesion can block ongoing RNA transcription and DNA replication and thus cause genome instability and cancer. Several cellular defense mechanism, such as the Fanconi anemia pathway have developed to ensure accurate repair and DNA replication when ICLs are present. Various structure-specific nucleases and translesion synthesis (TLS) polymerases have come into focus in relation to ICL bypass. Current models propose that a structure-specific nuclease incision is needed to unhook the ICL from the replication fork, followed by the activity of a low-fidelity TLS polymerase enabling replication through the unhooked ICL adduct. This review focuses on how, in parallel with the Fanconi anemia pathway, PCNA interactions and ICL-induced PCNA ubiquitylation regulate the recruitment, substrate specificity, activity, and coordinated action of certain nucleases and TLS polymerases in the execution of stalled replication fork rescue via ICL bypass.

Sign in / Sign up

Export Citation Format

Share Document