scholarly journals Human DNA ligases I and III, but not ligase IV, are required for microhomology-mediated end joining of DNA double-strand breaks

2008 ◽  
Vol 36 (10) ◽  
pp. 3297-3310 ◽  
Author(s):  
L. Liang ◽  
L. Deng ◽  
S. C. Nguyen ◽  
X. Zhao ◽  
C. D. Maulion ◽  
...  
Keyword(s):  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Ligases ◽  
Human Dna ◽  
Ligase Iv

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 Unexpected behavior of DNA polymerase Mu opposite template 8-oxo-7,8-dihydro-2′-guanosine

2019 ◽  
Vol 47 (17) ◽  
pp. 9410-9422 ◽  
Author(s):  
Andrea M Kaminski ◽  
Kishore K Chiruvella ◽  
Dale A Ramsden ◽  
Thomas A Kunkel ◽  
Katarzyna Bebenek ◽  
...  
Keyword(s):  
Double Strand Breaks ◽  
Nonhomologous End Joining ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Steady State Kinetics ◽  
Ligase Iv ◽  
Template Dna ◽  
Dna Substrate

Abstract DNA double-strand breaks (DSBs) resulting from reactive oxygen species generated by exposure to UV and ionizing radiation are characterized by clusters of lesions near break sites. Such complex DSBs are repaired slowly, and their persistence can have severe consequences for human health. We have therefore probed DNA break repair containing a template 8-oxo-7,8-dihydro-2′-guanosine (8OG) by Family X Polymerase μ (Pol μ) in steady-state kinetics and cell-based assays. Pol μ tolerates 8OG-containing template DNA substrates, and the filled products can be subsequently ligated by DNA Ligase IV during Nonhomologous end-joining. Furthermore, Pol μ exhibits a strong preference for mutagenic bypass of 8OG by insertion of adenine. Crystal structures reveal that the template 8OG is accommodated in the Pol μ active site with none of the DNA substrate distortions observed for Family X siblings Pols β or λ. Kinetic characterization of template 8OG bypass indicates that Pol μ inserts adenosine nucleotides with weak sugar selectivity and, given the high cellular concentration of ATP, likely performs its role in repair of complex 8OG-containing DSBs using ribonucleotides.

scholarly journals Association of DNA Polymerase μ (pol μ) with Ku and Ligase IV: Role for pol μ in End-Joining Double-Strand Break Repair

2002 ◽  
Vol 22 (14) ◽  
pp. 5194-5202 ◽  
Author(s):  
Kiran N. Mahajan ◽  
Stephanie A. Nick McElhinny ◽  
Beverly S. Mitchell ◽  
Dale A. Ramsden
Keyword(s):  
Dna Polymerase ◽  
Cellular Response ◽  
Double Strand Breaks ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Stable Complex ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Cell Extracts ◽  
Ligase Iv

ABSTRACT Mammalian DNA polymerase μ (pol μ) is related to terminal deoxynucleotidyl transferase, but its biological role is not yet clear. We show here that after exposure of cells to ionizing radiation (IR), levels of pol μ protein increase. pol μ also forms discrete nuclear foci after IR, and these foci are largely coincident with IR-induced foci of γH2AX, a previously characterized marker of sites of DNA double-strand breaks. pol μ is thus part of the cellular response to DNA double-strand breaks. pol μ also associates in cell extracts with the nonhomologous end-joining repair factor Ku and requires both Ku and another end-joining factor, XRCC4-ligase IV, to form a stable complex on DNA in vitro. pol μ in turn facilitates both stable recruitment of XRCC4-ligase IV to Ku-bound DNA and ligase IV-dependent end joining. In contrast, the related mammalian DNA polymerase β does not form a complex with Ku and XRCC4-ligase IV and is less effective than pol μ in facilitating joining mediated by these factors. Our data thus support an important role for pol μ in the end-joining pathway for repair of double-strand breaks.

scholarly journals The Maize Transposable Element Ac Induces Recombination Between the Donor Site and an Homologous Ectopic Sequence

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 1143-1151
Author(s):  
Gil Shalev ◽  
Avraham A Levy
Keyword(s):  
Transposable Element ◽  
Donor Site ◽  
Double Strand Breaks ◽  
Plant Genome ◽  
Blue Staining ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Reading Frame ◽  
Strand Breaks ◽  
Ectopic Recombination

The prominent repair mechanism of DNA double-strand breaks formed upon excision of the maize Ac transposable element is via nonhomologous end joining. In this work we have studied the role of homologous recombination as an additional repair pathway. To this end, we developed an assay whereby β-Glucuronidase (GUS) activity is restored upon recombination between two homologous ectopic (nonallelic) sequences in transgenic tobacco plants. One of the recombination partners carried a deletion at the 5′ end of GUS and an Ac or a Ds element inserted at the deletion site. The other partner carried an intact 5′ end of the GUS open reading frame and had a deletion at the 3′ end of the gene. Based on GUS reactivation data, we found that the excision of Ac induced recombination between ectopic sequences by at least two orders of magnitude. Recombination events, visualized by blue staining, were detected in seedlings, in pollen and in protoplasts. DNA fragments corresponding to recombination events were recovered exclusively in crosses with Ac-carrying plants, providing physical evidence for Ac-induced ectopic recombination. The occurrence of ectopic recombination following double-strand breaks is a potentially important factor in plant genome evolution.

Role for Artemis nuclease in the repair of radiation-induced DNA double strand breaks by alternative end joining

DNA Repair ◽  
2015 ◽  
Vol 31 ◽  
pp. 29-40 ◽  
Author(s):  
Mario Moscariello ◽  
Radi Wieloch ◽  
Aya Kurosawa ◽  
Fanghua Li ◽  
Noritaka Adachi ◽  
...  
Keyword(s):  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Alternative End Joining ◽  
Radiation Induced

Involvement of Ku80 in microhomology-mediated end joining for DNA double-strand breaks in vivo

DNA Repair ◽  
2007 ◽  
Vol 6 (5) ◽  
pp. 639-648 ◽  
Author(s):  
Yukitaka Katsura ◽  
Shigeru Sasaki ◽  
Masanori Sato ◽  
Kiyoshi Yamaoka ◽  
Kazumi Suzukawa ◽  
...  
Keyword(s):  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks

scholarly journals Autophosphorylation of DNA-PKCS regulates its dynamics at DNA double-strand breaks

2007 ◽  
Vol 177 (2) ◽  
pp. 219-229 ◽  
Author(s):  
Naoya Uematsu ◽  
Eric Weterings ◽  
Ken-ichi Yano ◽  
Keiko Morotomi-Yano ◽  
Burkhard Jakob ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Laser System ◽  
Double Strand Breaks ◽  
Dependent Manner ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Dsb Repair ◽  
Strand Breaks ◽  
Dna Ends

The DNA-dependent protein kinase catalytic subunit (DNA-PKCS) plays an important role during the repair of DNA double-strand breaks (DSBs). It is recruited to DNA ends in the early stages of the nonhomologous end-joining (NHEJ) process, which mediates DSB repair. To study DNA-PKCS recruitment in vivo, we used a laser system to introduce DSBs in a specified region of the cell nucleus. We show that DNA-PKCS accumulates at DSB sites in a Ku80-dependent manner, and that neither the kinase activity nor the phosphorylation status of DNA-PKCS influences its initial accumulation. However, impairment of both of these functions results in deficient DSB repair and the maintained presence of DNA-PKCS at unrepaired DSBs. The use of photobleaching techniques allowed us to determine that the kinase activity and phosphorylation status of DNA-PKCS influence the stability of its binding to DNA ends. We suggest a model in which DNA-PKCS phosphorylation/autophosphorylation facilitates NHEJ by destabilizing the interaction of DNA-PKCS with the DNA ends.

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