scholarly journals Nonsurgical endodontic management of mandibular first premolar with incomplete root‐end resection

2020 ◽  
Author(s):  
Khaled Al‐Manei ◽  
Kholod Khalil Al‐Manei
Keyword(s):  
Mandibular First Premolar ◽  
End Resection

Repair pathway choice for double-strand breaks

2020 ◽  
Vol 64 (5) ◽  
pp. 765-777 ◽  
Author(s):  
Yixi Xu ◽  
Dongyi Xu
Keyword(s):  
Cell Cycle ◽  
Double Strand Breaks ◽  
Homologous Region ◽  
Gene Repair ◽  
Repair Pathway ◽  
Dna Double Strand Breaks ◽  
Environmental Radiation ◽  
Strand Breaks ◽  
Dna End Resection ◽  
End Resection

Abstract Deoxyribonucleic acid (DNA) is at a constant risk of damage from endogenous substances, environmental radiation, and chemical stressors. DNA double-strand breaks (DSBs) pose a significant threat to genomic integrity and cell survival. There are two major pathways for DSB repair: nonhomologous end-joining (NHEJ) and homologous recombination (HR). The extent of DNA end resection, which determines the length of the 3′ single-stranded DNA (ssDNA) overhang, is the primary factor that determines whether repair is carried out via NHEJ or HR. NHEJ, which does not require a 3′ ssDNA tail, occurs throughout the cell cycle. 53BP1 and the cofactors PTIP or RIF1-shieldin protect the broken DNA end, inhibit long-range end resection and thus promote NHEJ. In contrast, HR mainly occurs during the S/G2 phase and requires DNA end processing to create a 3′ tail that can invade a homologous region, ensuring faithful gene repair. BRCA1 and the cofactors CtIP, EXO1, BLM/DNA2, and the MRE11–RAD50–NBS1 (MRN) complex promote DNA end resection and thus HR. DNA resection is influenced by the cell cycle, the chromatin environment, and the complexity of the DNA end break. Herein, we summarize the key factors involved in repair pathway selection for DSBs and discuss recent related publications.

scholarly journals DHX9-dependent recruitment of BRCA1 to RNA promotes DNA end resection in homologous recombination

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Prasun Chakraborty ◽  
Kevin Hiom
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Rna Polymerase Ii ◽  
Critical Role ◽  
Dna Breaks ◽  
Double Stranded Dna ◽  
Recombination Repair ◽  
Dna End Resection ◽  
End Resection ◽  
Rna Polymerase Ii Transcription

AbstractDouble stranded DNA Breaks (DSB) that occur in highly transcribed regions of the genome are preferentially repaired by homologous recombination repair (HR). However, the mechanisms that link transcription with HR are unknown. Here we identify a critical role for DHX9, a RNA helicase involved in the processing of pre-mRNA during transcription, in the initiation of HR. Cells that are deficient in DHX9 are impaired in the recruitment of RPA and RAD51 to sites of DNA damage and fail to repair DSB by HR. Consequently, these cells are hypersensitive to treatment with agents such as camptothecin and Olaparib that block transcription and generate DSB that specifically require HR for their repair. We show that DHX9 plays a critical role in HR by promoting the recruitment of BRCA1 to RNA as part of the RNA Polymerase II transcription complex, where it facilitates the resection of DSB. Moreover, defects in DHX9 also lead to impaired ATR-mediated damage signalling and an inability to restart DNA replication at camptothecin-induced DSB. Together, our data reveal a previously unknown role for DHX9 in the DNA Damage Response that provides a critical link between RNA, RNA Pol II and the repair of DNA damage by homologous recombination.

ASTE1 promotes shieldin-complex-mediated DNA repair by attenuating end resection

2021 ◽  
Author(s):  
Fei Zhao ◽  
Wootae Kim ◽  
Huanyao Gao ◽  
Chao Liu ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Dna Repair ◽  
End Resection

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.

scholarly journals Root-end resection

2012 ◽  
Vol 113 (04) ◽  
pp. 240-242
Author(s):  
R. Blahuta ◽  
P. Stanko
Keyword(s):  
End Resection

scholarly journals Sae2 antagonizes Rad9 accumulation at DNA double-strand breaks to attenuate checkpoint signaling and facilitate end resection

2018 ◽  
Vol 115 (51) ◽  
pp. E11961-E11969 ◽  
Author(s):  
Tai-Yuan Yu ◽  
Michael T. Kimble ◽  
Lorraine S. Symington
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Inhibitory Effects ◽  
Checkpoint Signaling ◽  
Synthetic Lethal ◽  
Strand Breaks ◽  
Damage Response ◽  
End Resection

The Mre11-Rad50-Xrs2NBS1 complex plays important roles in the DNA damage response by activating the Tel1ATM kinase and catalyzing 5′–3′ resection at DNA double-strand breaks (DSBs). To initiate resection, Mre11 endonuclease nicks the 5′ strands at DSB ends in a reaction stimulated by Sae2CtIP. Accordingly, Mre11-nuclease deficient (mre11-nd) and sae2Δ mutants are expected to exhibit similar phenotypes; however, we found several notable differences. First, sae2Δ cells exhibit greater sensitivity to genotoxins than mre11-nd cells. Second, sae2Δ is synthetic lethal with sgs1Δ, whereas the mre11-nd sgs1Δ mutant is viable. Third, Sae2 attenuates the Tel1-Rad53CHK2 checkpoint and antagonizes Rad953BP1 accumulation at DSBs independent of Mre11 nuclease. We show that Sae2 competes with other Tel1 substrates, thus reducing Rad9 binding to chromatin and to Rad53. We suggest that persistent Sae2 binding at DSBs in the mre11-nd mutant counteracts the inhibitory effects of Rad9 and Rad53 on Exo1 and Dna2-Sgs1–mediated resection, accounting for the different phenotypes conferred by mre11-nd and sae2Δ mutations. Collectively, these data show a resection initiation independent role for Sae2 at DSBs by modulating the DNA damage checkpoint.

scholarly journals HELB Is a Feedback Inhibitor of DNA End Resection

2016 ◽  
Vol 61 (3) ◽  
pp. 405-418 ◽  
Author(s):  
Ján Tkáč ◽  
Guotai Xu ◽  
Hemanta Adhikary ◽  
Jordan T.F. Young ◽  
David Gallo ◽  
...  
Keyword(s):  
Feedback Inhibitor ◽  
Dna End Resection ◽  
End Resection

scholarly journals SAMHD1 Promotes DNA End Resection to Facilitate DNA Repair by Homologous Recombination

Cell Reports ◽  
2017 ◽  
Vol 20 (8) ◽  
pp. 1921-1935 ◽  
Author(s):  
Waaqo Daddacha ◽  
Allyson E. Koyen ◽  
Amanda J. Bastien ◽  
PamelaSara E. Head ◽  
Vishal R. Dhere ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Dna End Resection ◽  
End Resection
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