Distinct cellular phenotype linked to defective DNA interstrand crosslink repair and homologous recombination
Repair of DNA interstrand crosslinks (ICLs) predominantly involves the Fanconi anemia (FA) pathway and homologous recombination (HR). The HR repair system eliminates DNA double strand breaks (DSBs) that emerge during ICLs removal. The current study presents a novel cell line, CLV8B,
representing a new complementation group of Chinese hamster cell mutants hypersensitive to DNA crosslinking factors. CLV8B exhibits increased sensitivity to various DNAdamaging agents, including compounds leading to DSBs formation (bleomycin and 6thioguanine), and is extremely sensitive to
poly (ADP-ribose) polymerase inhibitor (>400fold), which is typical for HRdefective cells. In addition, this cell line exhibits a reduced number of spontaneous and induced sister chromatid exchanges, which suggests likely impairment of HR in CLV8B cells. However, in contrast to other known
HR mutants, CLV8B cells do not show defects in Rad51 foci induction, but only slight alterations in the focus formation kinetics. CLV8B is additionally characterized by a considerable chromosomal instability, as indicated by a high number of spontaneous and MMCinduced chromosomal aberrations,
and a twice as large proportion of cells with abnormal centrosomes than that in the wild type cell line. The molecular defect present in CLV8B does not affect the efficiency and stabilization of replication forks. However, stalling of the forks in response to replication stress is observed
relatively rarely, which suggests an impairment of a signaling mechanism. Exposure of CLV8B to crosslinking agents results in Sphase arrest (as in the wild type cells), but also in larger proportion of G2/Mphase cells and apoptotic cells. CLV8B exhibits similarities to HR and/or FAdefective
Chinese hamster mutants sensitive to DNA crosslinking agents. However, the unique phenotype of this new mutant implies that it carries a defect of a yet unidentified gene involved in the repair of ICLs.
Document Type: Research Article
Affiliations: 1: Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, Bydgoszcz 85094, Poland 2: Department of Human Molecular Genetics, Adam Mickiewicz University, Poznan 61614, Poland 3: Department of Immunology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, Bydgoszcz 85094, Poland 4: Innovative Medical Forum, Franciszek Lukaszczyk Oncology Center, Bydgoszcz 85796, Poland
Publication date: 01 August 2017
- Molecular Medicine Reports is a monthly, peer-reviewed journal available in print and online, that includes studies devoted to molecular medicine, underscoring aspects including pharmacology, pathology, genetics, neurosciences, infectious diseases, molecular cardiology and molecular surgery. In vitro and in vivo studies of experimental model systems pertaining to the mechanisms of a variety of diseases offer researchers the necessary tools and knowledge with which to aid the diagnosis and treatment of human diseases.
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