scholarly journals Recruitment of MRE-11 to complex DNA damage is modulated by meiosis-specific chromosome organization

2020 ◽  
Author(s):  
Kailey Harrell ◽  
Madison Day ◽  
Sarit Smolikove
Keyword(s):  
Dna Damage ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Damage Response ◽  
Non Homologous End Joining ◽  
Altered Form ◽  
Laser Microirradiation ◽  
Clustered Dna Damage

AbstractDNA double-strand breaks (DSBs) are one of the most dangerous assaults on the genome, and yet their natural and programmed production are inherent to life. When DSBs arise close together (clustered) they are particularly deleterious, and their repair may require an altered form of the DNA damage response. Our understanding of how clustered DSBs are repaired in the germline is unknown. Using UV laser microirradiation, we examine early events in the repair of clustered DSBs in germ cells within whole, live, Caenorhabditis elegans. We use precise temporal resolution to show how the recruitment of MRE-11 to complex damage is regulated, and that clustered DNA damage can recruit proteins from various repair pathways. Abrogation of non-homologous end joining or COM-1 attenuates the recruitment of MRE-11 through distinct mechanisms. The synaptonemal complex plays both positive and negative regulatory roles in these mutant contexts. These findings together indicate that MRE-11 is regulated by modifying its accessibility to chromosomes.

scholarly journals Regulation of DNA Double-Strand Break Repair by Non-Coding RNAs

2018 ◽  
Author(s):  
Roopa Thapar
Keyword(s):  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Protein Dna Interactions ◽  
Damage Response ◽  
Non Coding Rnas ◽  
Non Homologous End Joining

DNA double-strand breaks (DSBs) are deleterious lesions that are generated in response to ionizing radiation or replication fork collapse that can lead to genomic instability and cancer.  Eukaryotes have evolved two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ) to repair DSBs.  Whereas the roles of protein-DNA interactions in HR and NHEJ have been fairly well defined, the functions of small and long non-coding RNAs and RNA-DNA hybrids in the DNA damage response is just beginning to be elucidated.  This review summarizes recent discoveries on the identification of non-coding RNAs and RNA-mediated regulation of DSB repair

scholarly journals SIRT6 is a DNA Double-Strand Break Sensor

2019 ◽  
Author(s):  
Lior Onn ◽  
Miguel Portillo ◽  
Stefan Ilic ◽  
Gal Cleitman ◽  
Daniel Stein ◽  
...  
Keyword(s):  
Dna Damage ◽  
Binding Capacity ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
The Road ◽  
Non Homologous End Joining

AbstractDNA double strand breaks are the most deleterious type of DNA damage. In this work, we show that SIRT6 directly recognizes DNA damage through a tunnel-like structure, with high affinity for double strand breaks. It relocates to sites of damage independently of signalling and known sensors and activates downstream signalling cascades for double strand break repair by triggering ATM recruitment, H2AX phosphorylation and the recruitment of proteins of the Homologous Recombination and Non-Homologous End Joining pathways. Our findings indicate that SIRT6 plays a previously uncharacterized role as DNA damage sensor, which is critical for initiating the DNA damage response (DDR). Moreover, other Sirtuins share some DSB binding capacity and DDR activation. SIRT6 activates the DDR, before the repair pathway is chosen, and prevents genomic instability. Our findings place SIRT6 at the top of the DDR and pave the road to dissect the contributions of distinct double strand break sensors in downstream signalling.

scholarly journals Regulation of DNA Double-Strand Break Repair by Non-Coding RNAs

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2789 ◽  
Author(s):  
Roopa Thapar
Keyword(s):  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Protein Dna Interactions ◽  
Damage Response ◽  
Non Coding Rnas ◽  
Non Homologous End Joining

DNA double-strand breaks (DSBs) are deleterious lesions that are generated in response to ionizing radiation or replication fork collapse that can lead to genomic instability and cancer. Eukaryotes have evolved two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ) to repair DSBs. Whereas the roles of protein-DNA interactions in HR and NHEJ have been fairly well defined, the functions of small and long non-coding RNAs and RNA-DNA hybrids in the DNA damage response is just beginning to be elucidated. This review summarizes recent discoveries on the identification of non-coding RNAs and RNA-mediated regulation of DSB repair.

scholarly journals Altered DNA ligase activity in human disease

Mutagenesis ◽  
2019 ◽  
Vol 35 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Alan E Tomkinson ◽  
Tasmin Naila ◽  
Seema Khattri Bhandari
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Double Strand Breaks ◽  
Dna Ligase ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Ligases ◽  
Ligase Iv ◽  
Non Homologous End Joining

Abstract The joining of interruptions in the phosphodiester backbone of DNA is critical to maintain genome stability. These breaks, which are generated as part of normal DNA transactions, such as DNA replication, V(D)J recombination and meiotic recombination as well as directly by DNA damage or due to DNA damage removal, are ultimately sealed by one of three human DNA ligases. DNA ligases I, III and IV each function in the nucleus whereas DNA ligase III is the sole enzyme in mitochondria. While the identification of specific protein partners and the phenotypes caused either by genetic or chemical inactivation have provided insights into the cellular functions of the DNA ligases and evidence for significant functional overlap in nuclear DNA replication and repair, different results have been obtained with mouse and human cells, indicating species-specific differences in the relative contributions of the DNA ligases. Inherited mutations in the human LIG1 and LIG4 genes that result in the generation of polypeptides with partial activity have been identified as the causative factors in rare DNA ligase deficiency syndromes that share a common clinical symptom, immunodeficiency. In the case of DNA ligase IV, the immunodeficiency is due to a defect in V(D)J recombination whereas the cause of the immunodeficiency due to DNA ligase I deficiency is not known. Overexpression of each of the DNA ligases has been observed in cancers. For DNA ligase I, this reflects increased proliferation. Elevated levels of DNA ligase III indicate an increased dependence on an alternative non-homologous end-joining pathway for the repair of DNA double-strand breaks whereas elevated level of DNA ligase IV confer radioresistance due to increased repair of DNA double-strand breaks by the major non-homologous end-joining pathway. Efforts to determine the potential of DNA ligase inhibitors as cancer therapeutics are on-going in preclinical cancer models.

scholarly journals Regulation of DNA Double-Strand Break Repair by Non-Coding RNAs

2018 ◽  
Author(s):  
Roopa Thapar
Keyword(s):  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Protein Dna Interactions ◽  
Damage Response ◽  
Non Coding Rnas ◽  
Non Homologous End Joining

DNA double-strand breaks (DSBs) are deleterious lesions that are generated in response to ionizing radiation or replication fork collapse that can lead to genomic instability and cancer.  Eukaryotes have evolved two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ) to repair DSBs.  Whereas the roles of protein-DNA interactions in HR and NHEJ have been fairly well defined, the functions of small and long non-coding RNAs and RNA-DNA hybrids in the DNA damage response is just beginning to be elucidated.  This review summarizes recent discoveries on the identification of non-coding RNAs and RNA-mediated regulation of DSB repair

scholarly journals Regulation of DNA Double-Strand Break Repair by Non-Coding RNAs

2018 ◽  
Author(s):  
Roopa Thapar
Keyword(s):  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Protein Dna Interactions ◽  
Damage Response ◽  
Non Coding Rnas ◽  
Non Homologous End Joining

DNA double-strand breaks (DSBs) are deleterious lesions that are generated in response to ionizing radiation or replication fork collapse that can lead to genomic instability and cancer.  Eukaryotes have evolved two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ) to repair DSBs.  Whereas the roles of protein-DNA interactions in HR and NHEJ have been fairly well defined, the functions of small and long non-coding RNAs and RNA-DNA hybrids in the DNA damage response is just beginning to be elucidated.  This review summarizes recent discoveries on the identification of non-coding RNAs and RNA-mediated regulation of DSB repair

scholarly journals LC8/DYNLL1 is a 53BP1 effector and regulates checkpoint activation

2019 ◽  
Vol 47 (12) ◽  
pp. 6236-6249 ◽  
Author(s):  
Kirk L West ◽  
Jessica L Kelliher ◽  
Zhanzhan Xu ◽  
Liwei An ◽  
Megan R Reed ◽  
...  
Keyword(s):  
Dna Damage ◽  
Double Strand Breaks ◽  
Parp Inhibition ◽  
Current Evidence ◽  
Dependent Manner ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Checkpoint Activation ◽  
Strand Breaks ◽  
Non Homologous End Joining

Abstract The tumor suppressor protein 53BP1 plays key roles in response to DNA double-strand breaks (DSBs) by serving as a master scaffold at the damaged chromatin. Current evidence indicates that 53BP1 assembles a cohort of DNA damage response (DDR) factors to distinctly execute its repertoire of DSB responses, including checkpoint activation and non-homologous end joining (NHEJ) repair. Here, we have uncovered LC8 (a.k.a. DYNLL1) as an important 53BP1 effector. We found that LC8 accumulates at laser-induced DNA damage tracks in a 53BP1-dependent manner and requires the canonical H2AX-MDC1-RNF8-RNF168 signal transduction cascade. Accordingly, genetic inactivation of LC8 or its interaction with 53BP1 resulted in checkpoint defects. Importantly, loss of LC8 alleviated the hypersensitivity of BRCA1-depleted cells to ionizing radiation and PARP inhibition, highlighting the 53BP1-LC8 module in counteracting BRCA1-dependent functions in the DDR. Together, these data establish LC8 as an important mediator of a subset of 53BP1-dependent DSB responses.

scholarly journals DROSHA is recruited to DNA damage sites by the MRN complex to promote non-homologous end-joining

2021 ◽  
pp. jcs.249706
Author(s):  
Matteo Cabrini ◽  
Marco Roncador ◽  
Alessandro Galbiati ◽  
Lina Cipolla ◽  
Antonio Maffia ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Mrn Complex ◽  
Break Site ◽  
Non Homologous End Joining ◽  
Dna Ends

The DNA damage response (DDR) is the signaling cascade that recognizes DNA double-strand breaks (DSB) and promotes their resolution via the DNA repair pathways of Non-Homologous End Joining (NHEJ) or Homologous Recombination (HR). We and others have shown that DDR activation requires DROSHA. However, whether DROSHA exerts its functions by associating with damage sites, what controls its recruitment and how DROSHA influences DNA repair, remains poorly understood. Here we show that DROSHA associates to DSBs independently from transcription. Neither H2AX, nor ATM nor DNA-PK kinase activities are required for its recruitment to break site. Rather, DROSHA interacts with RAD50 and inhibition of MRN by Mirin treatment abolishes this interaction. MRN inactivation by RAD50 knockdown or mirin treatment prevents DROSHA recruitment to DSB and, as a consequence, also 53BP1 recruitment. During DNA repair, DROSHA inactivation reduces NHEJ and boosts HR frequency. Indeed, DROSHA knockdown also increase the association of downstream HR factors such as RAD51 to DNA ends. Overall, our results demonstrate that DROSHA is recruited at DSBs by the MRN complex and direct DNA repair toward NHEJ.

scholarly journals RepID-deficient cancer cells are sensitized to a drug targeting p97/VCP segregase

2021 ◽  
Author(s):  
Sang-Min Jang ◽  
Christophe E. Redon ◽  
Haiqing Fu ◽  
Fred E. Indig ◽  
Mirit I. Aladjem
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Cell Sorting ◽  
Clonogenic Survival ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Ubiquitinated Proteins ◽  
Damage Response ◽  
Survival Assay

Abstract Background The p97/valosin-containing protein (VCP) complex is a crucial factor for the segregation of ubiquitinated proteins in the DNA damage response and repair pathway. Objective We investigated whether blocking the p97/VCP function can inhibit the proliferation of RepID-deficient cancer cells using immunofluorescence, clonogenic survival assay, fluorescence-activated cell sorting, and immunoblotting. Result p97/VCP was recruited to chromatin and colocalized with DNA double-strand breaks in RepID-deficient cancer cells that undergo spontaneous DNA damage. Inhibition of p97/VCP induced death of RepID-depleted cancer cells. This study highlights the potential of targeting p97/VCP complex as an anticancer therapeutic approach. Conclusion Our results show that RepID is required to prevent excessive DNA damage at the endogenous levels. Localization of p97/VCP to DSB sites was induced based on spontaneous DNA damage in RepID-depleted cancer cells. Anticancer drugs targeting p97/VCP may be highly potent in RepID-deficient cells. Therefore, we suggest that p97/VCP inhibitors synergize with RepID depletion to kill cancer cells.

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