scholarly journals REV7/FANCV Binds to CHAMP1 and Promotes Homologous Recombination Repair

2021 ◽  
Author(s):  
Feng Li ◽  
Prabha Sarangi ◽  
Hanrong Feng ◽  
Lisa Moreau ◽  
Huy Nguyen ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Parp Inhibitor ◽  
Dna Double Strand Breaks ◽  
Critical Determinant ◽  
Strand Breaks ◽  
Positive Regulator ◽  
Recombination Repair ◽  
Nhej Repair ◽  
Inhibitor Resistance

A critical determinant of DNA repair pathway choice is the HORMA protein REV7, a small abundant adaptor which binds to various DNA repair proteins through its C-terminal seatbelt domain. The REV7 seatbelt binds to the REV3 polymerase to form the Polymerase ζ complex, a positive regulator of translesion synthesis (TLS) repair. Alternatively, the REV7 seatbelt binds to SHLD3 in the Shieldin complex, a positive regulator of NHEJ repair. Recent studies have identified another novel REV7 seatbelt-binding protein, CHAMP1 (Chromosome Alignment-Maintaining Phosphoprotein, though its role in DNA repair is unknown. Here, we show that the REV7-CHAMP1 complex promotes homologous recombination (HR) repair by sequestering REV7 from the Shieldin complex. CHAMP1 competes directly with the SHLD3 subunit of the Shieldin complex for a limited pool of C-REV7, thereby inhibiting the REV7-mediated recruitment of the SHLD2 and SHLD1 effector subunits to DNA double strand breaks. CHAMP1 thereby channels DNA repair away from error-prone NHEJ and towards the competing error-free HR pathway. Similarly, CHAMP1 competes with the REV3 component of the POLζ complex, thereby reducing the level of mutagenic TLS repair. CHAMP1 interacts with POGZ in a heterochromatin complex further promoting HR repair. Importantly, in human tumors, CHAMP1 overexpression promotes HR, confers PARP inhibitor resistance, and correlates with poor prognosis. Thus, by binding to either REV3, SHLD3, or CHAMP1 through its seatbelt, the REV7 protein can promote either TLS repair, NHEJ repair, or HR repair respectively.

scholarly journals REV7/FANCV Binds to CAMP and Promotes Homologous Recombination Repair

2021 ◽  
Author(s):  
Feng Li ◽  
Prabha Sarangi ◽  
Hanrong Feng ◽  
Lisa Moreau ◽  
Huy Nguyen ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Parp Inhibitor ◽  
Binding Activity ◽  
Dna Double Strand Breaks ◽  
Critical Determinant ◽  
Positive Regulator ◽  
Chromosome Alignment ◽  
Nhej Repair ◽  
Inhibitor Resistance

Abstract A critical determinant of DNA repair pathway choice is the HORMA protein REV7, a small abundant adaptor which binds to various DNA repair proteins through its C-terminal seatbelt domain. The REV7 seatbelt binds to the REV3 polymerase to form the Polymerase ζ complex, a positive regulator of translesion synthesis (TLS) repair. Alternatively, the REV7 seatbelt binds to SHLD3 in the Shieldin complex, a positive regulator of NHEJ repair. Recent studies have identified another novel REV7 seatbelt-binding protein, CAMP (Chromosome Alignment-Maintaining Phosphoprotein), though its role in DNA repair is unknown. Here, we show that the REV7-CAMP complex promotes homologous recombination (HR) repair by sequestering REV7 from the Shieldin complex. CAMP competes directly with the SHLD3 subunit of the Shieldin complex for a limited pool of C-REV7, thereby inhibiting the REV7-mediated recruitment of the SHLD2 and SHLD1 effector subunits to DNA double strand breaks. CAMP thereby channels DNA repair away from error-prone NHEJ and towards the competing error-free HR pathway. Similarly, CAMP competes with the REV3 component of the POL-Zeta complex, thereby reducing the level of mutagenic TLS repair. CAMP has a distinct function in promoting chromosome alignment which is independent of its REV7 binding activity. Importantly, in human tumors, CAMP overexpression promotes HR, confers PARP inhibitor resistance, and correlates with poor prognosis. Thus, by binding to either REV3, SHLD3, or CAMP through its seatbelt, the REV7 protein can promote either TLS repair, NHEJ repair, or HR repair respectively.

scholarly journals End-resection at DNA double-strand breaks in the three domains of life

2013 ◽  
Vol 41 (1) ◽  
pp. 314-320 ◽  
Author(s):  
John K. Blackwood ◽  
Neil J. Rzechorzek ◽  
Sian M. Bray ◽  
Joseph D. Maman ◽  
Luca Pellegrini ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Domains Of Life ◽  
Strand Invasion ◽  
End Resection

During DNA repair by HR (homologous recombination), the ends of a DNA DSB (double-strand break) must be resected to generate single-stranded tails, which are required for strand invasion and exchange with homologous chromosomes. This 5′–3′ end-resection of the DNA duplex is an essential process, conserved across all three domains of life: the bacteria, eukaryota and archaea. In the present review, we examine the numerous and redundant helicase and nuclease systems that function as the enzymatic analogues for this crucial process in the three major phylogenetic divisions.

141 INDICATIONS FOR DNA DOUBLE-STRAND BREAK REPAIR IN EARLY BOVINE EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 188
Author(s):  
A. Brero ◽  
D. Koehler ◽  
T. Cremer ◽  
E. Wolf ◽  
V. Zakhartchenko
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Dna Lesions ◽  
Homologous Recombination Repair ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Male And Female ◽  
Γh2ax Foci ◽  
Recombination Repair

DNA double-strand breaks (DSBs) are considered the most severe type of DNA lesions, because such lesions, if unrepaired, lead to a loss of genome integrity. Soon after induction of DSBs, chromatin surrounding the damage is modified by phosphorylation of the histone variant H2AX, generating so-called γH2AX, which is a hallmark of DSBs (Takahashi et al. 2005 Cancer Lett. 229, 171–179). γH2AX appears to be a signal for the recruitment of proteins constituting the DNA repair machinery. Depending on the type of damage and the cell cycle stage of the affected cell, DSBs are repaired either by nonhomologous end joining or by homologous recombination using the sister chromatid DNA as template (Hoeijmakers 2001 Nature 411, 366–374). We used immunofluorescence to analyze chromatin composition during bovine development and found γH2AX foci in both male and female pronuclei of IVF embryos. The number and size of foci varied considerably between embryos and between the male and female pronuclei. To test whether the observed γH2AX foci represented sites of active DNA repair, we co-stained IVF zygotes for γH2AX and 3 different proteins involved in homologous recombination repair of DSBs: NBS1 (phosphorylated at amino acid serine 343), 53BP1, and Rad51. We found co-localization of γH2AX foci with phosphorylated NBS1 as well as with Rad51 but did not observe the presence of 53BP1 at γH2AX foci in IVF zygotes. Our finding shows the presence of DSBs in IVF zygotes and suggests the capability of homologous recombination repair. The lack of 53BP1, a component of homologous recombination repair, which usually co-localizes with γH2AX foci at exogenously induced DSBs (Schultz et al. 2000 J. Cell. Biol. 151, 1381–1390) poses the possibility that the mechanism present in early embryos differs substantially from that involved in DNA repair of DSBs in somatic cells.

scholarly journals BLM-dependent Break-Induced Replication handles DSBs in transcribed chromatin upon impaired RNA:DNA hybrids dissolution

2020 ◽  
Author(s):  
S Cohen ◽  
A Guenolé ◽  
A Marnef ◽  
T Clouaire ◽  
N Puget ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Dna Helicase ◽  
Dependent Manner ◽  
Dna Double Strand Breaks ◽  
Critical Function ◽  
Strand Breaks ◽  
Recombination Repair ◽  
Rna:Dna Hybrids ◽  
Toxic Potential ◽  
Break Induced Replication

AbstractTranscriptionally active loci are particularly prone to breakage and mounting evidence suggest that DNA Double-Strand Breaks arising in genes are handled by a dedicated repair pathway, Transcription-Coupled DSB Repair (TC-DSBR), that entails R-loops accumulation and dissolution. Here, we uncovered a critical function of the Bloom RecQ DNA helicase (BLM) in TC-DSBR in human cells. BLM is recruited in a transcription dependent-manner at DSBs where it fosters resection, RAD51 binding and accurate Homologous Recombination repair. However, in a R-loop dissolution-deficient background BLM switches from promoting Homologous Recombination to promoting Break-Induced Replication (BIR), which strongly impairs cell viability. Altogether our work unveils a role for BLM in BIR at DSBs in active chromatin, and highlights the toxic potential of RNA:DNA hybrids that accumulate at these transcription-associated DSBs.

scholarly journals Chlamydia trachomatis Inhibits Homologous Recombination Repair of DNA Breaks by Interfering with PP2A Signaling

mBio ◽  
2018 ◽  
Vol 9 (6) ◽  
Author(s):  
Yang Mi ◽  
Rajendra Kumar Gurumurthy ◽  
Piotr K. Zadora ◽  
Thomas F. Meyer ◽  
Cindrilla Chumduri
Keyword(s):  
Cell Cycle ◽  
Chlamydia Trachomatis ◽  
Homologous Recombination ◽  
Double Strand Breaks ◽  
Host Cells ◽  
Dna Double Strand Breaks ◽  
Content Type ◽  
Strand Breaks ◽  
Recombination Repair ◽  
Infected Cells

ABSTRACT Cervical and ovarian cancers exhibit characteristic mutational signatures that are reminiscent of mutational processes, including defective homologous recombination (HR) repair. How these mutational processes are initiated during carcinogenesis is largely unclear. Chlamydia trachomatis infections are epidemiologically associated with cervical and ovarian cancers. Previously, we showed that C. trachomatis induces DNA double-strand breaks (DSBs) but suppresses Ataxia-telangiectasia mutated (ATM) activation and cell cycle checkpoints. The mechanisms by which ATM regulation is modulated and its consequences for the repair pathway in C. trachomatis-infected cells remain unknown. Here, we found that Chlamydia bacteria interfere with the usual response of PP2A to DSBs. As a result, PP2A activity remains high, as the level of inhibitory phosphorylation at Y307 remains unchanged following C. trachomatis-induced DSBs. Protein-protein interaction analysis revealed that C. trachomatis facilitates persistent interactions of PP2A with ATM, thus suppressing ATM activation. This correlated with a remarkable lack of homologous recombination (HR) repair in C. trachomatis-infected cells. Chemical inhibition of PP2A activity in infected cells released ATM from PP2A, resulting in ATM phosphorylation. Activated ATM was then recruited to DSBs and initiated downstream signaling, including phosphorylation of MRE11 and NBS1 and checkpoint kinase 2 (Chk2)-mediated activation of the G2/M cell cycle checkpoint in C. trachomatis-infected cells. Further, PP2A inhibition led to the restoration of C. trachomatis-suppressed HR DNA repair function. Taking the data together, this study revealed that C. trachomatis modulates PP2A signaling to suppress ATM activation to prevent cell cycle arrest, thus contributing to a deficient high-fidelity HR pathway and a conducive environment for mutagenesis. IMPORTANCE Chlamydia trachomatis induces DNA double-strand breaks in host cells but simultaneously inhibits proper DNA damage response and repair mechanisms. This may render host cells prone to loss of genetic integrity and transformation. Here we show that C. trachomatis prevents activation of the key DNA damage response mediator ATM by preventing the release from PP2A, leading to a complete absence of homologous recombination repair in host cells.

scholarly journals A complex of BRCA2 and PP2A-B56 is required for DNA repair by homologous recombination

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sara M. Ambjørn ◽  
Julien P. Duxin ◽  
Emil P. T. Hertz ◽  
Isha Nasa ◽  
Joana Duro ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Parp Inhibition ◽  
Binding Motif ◽  
Filament Formation ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Atr Kinases

AbstractMutations in the tumour suppressor gene BRCA2 are associated with predisposition to breast and ovarian cancers. BRCA2 has a central role in maintaining genome integrity by facilitating the repair of toxic DNA double-strand breaks (DSBs) by homologous recombination (HR). BRCA2 acts by controlling RAD51 nucleoprotein filament formation on resected single-stranded DNA, but how BRCA2 activity is regulated during HR is not fully understood. Here, we delineate a pathway where ATM and ATR kinases phosphorylate a highly conserved region in BRCA2 in response to DSBs. These phosphorylations stimulate the binding of the protein phosphatase PP2A-B56 to BRCA2 through a conserved binding motif. We show that the phosphorylation-dependent formation of the BRCA2-PP2A-B56 complex is required for efficient RAD51 filament formation at sites of DNA damage and HR-mediated DNA repair. Moreover, we find that several cancer-associated mutations in BRCA2 deregulate the BRCA2-PP2A-B56 interaction and sensitize cells to PARP inhibition. Collectively, our work uncovers PP2A-B56 as a positive regulator of BRCA2 function in HR with clinical implications for BRCA2 and PP2A-B56 mutated cancers.

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