scholarly journals Critical Role of RecN in Recombinational DNA Repair and Survival of Helicobacter pylori

2007 ◽  
Vol 76 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Ge Wang ◽  
Robert J. Maier
Keyword(s):  
Helicobacter Pylori ◽  
Parent Strain ◽  
Dna Recombination ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Air Exposure ◽  
Strand Breaks ◽  
H Pylori

ABSTRACT Homologous recombination is one of the key mechanisms responsible for the repair of DNA double-strand breaks. Recombinational repair normally requires a battery of proteins, each with specific DNA recognition, strand transfer, resolution, or other functions. Helicobacter pylori lacks many of the proteins normally involved in the early stage (presynapsis) of recombinational repair, but it has a RecN homologue with an unclear function. A recN mutant strain of H. pylori was shown to be much more sensitive than its parent to mitomycin C, an agent predominantly causing DNA double-strand breaks. The recN strain was unable to survive exposure to either air or acid as well as the parent strain, and air exposure resulted in no viable recN cells recovered after 8 h. In oxidative stress conditions (i.e., air exposure), a recN strain accumulated significantly more damaged (multiply fragmented) DNA than the parent strain. To assess the DNA recombination abilities of strains, their transformation abilities were compared by separately monitoring transformation using H. pylori DNA fragments containing either a site-specific mutation (conferring rifampin resistance) or a large insertion (kanamycin resistance cassette). The transformation frequencies using the two types of DNA donor were 10- and 50-fold lower, respectively, for the recN strain than for the wild type, indicating that RecN plays an important role in facilitating DNA recombination. In two separate mouse colonization experiments, the recN strain colonized most of the stomachs, but the average number of recovered cells was 10-fold less for the mutant than for the parent strain (a statistically significant difference). Complementation of the recN strain by chromosomal insertion of a functional recN gene restored both the recombination frequency and mouse colonization ability to the wild-type levels. Thus, H. pylori RecN, as a component of DNA recombinational repair, plays a significant role in H. pylori survival in vivo.

scholarly journals Helicobacter pylori Infection Introduces DNA Double-Strand Breaks in Host Cells

2014 ◽  
Vol 82 (10) ◽  
pp. 4182-4189 ◽  
Author(s):  
Katsuhiro Hanada ◽  
Tomohisa Uchida ◽  
Yoshiyuki Tsukamoto ◽  
Masahide Watada ◽  
Nahomi Yamaguchi ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Genomic Instability ◽  
Double Strand Breaks ◽  
Host Cells ◽  
Dna Double Strand Breaks ◽  
Content Type ◽  
Strand Breaks ◽  
H Pylori

ABSTRACTGastric cancer is an inflammation-related malignancy related to long-standing acute and chronic inflammation caused by infection with the human bacterial pathogenHelicobacter pylori. Inflammation can result in genomic instability. However, there are considerable data thatH. pyloriitself can also produce genomic instability both directly and through epigenetic pathways. Overall, the mechanisms ofH. pylori-induced host genomic instabilities remain poorly understood. We used microarray screening ofH. pylori-infected human gastric biopsy specimens to identify candidate genes involved inH. pylori-induced host genomic instabilities. We found upregulation ofATMexpressionin vivoin gastric mucosal cells infected withH. pylori. Using gastric cancer cell lines, we confirmed that theH. pylori-related activation of ATM was due to the accumulation of DNA double-strand breaks (DSBs). DSBs were observed following infection with bothcagpathogenicity island (PAI)-positive and -negative strains, but the effect was more robust withcagPAI-positive strains. These results are consistent with the fact that infections with bothcagPAI-positive and -negative strains are associated with gastric carcinogenesis, but the risk is higher in individuals infected withcagPAI-positive strains.

scholarly journals H. pylori infection alters repair of DNA double-strand breaks via SNHG17

2020 ◽  
Vol 130 (7) ◽  
pp. 3901-3918
Author(s):  
Taotao Han ◽  
Xiaohui Jing ◽  
Jiayu Bao ◽  
Lianmei Zhao ◽  
Aidong Zhang ◽  
...  
Keyword(s):  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
H Pylori

scholarly journals The Karyopherin Kap142p/Msn5p Mediates Nuclear Import and Nuclear Export of Different Cargo Proteins

2001 ◽  
Vol 152 (4) ◽  
pp. 729-740 ◽  
Author(s):  
Kimihisa Yoshida ◽  
Günter Blobel
Keyword(s):  
Nuclear Import ◽  
Nuclear Export ◽  
Protein Import ◽  
Protein A ◽  
Double Strand Breaks ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Highly Sensitive ◽  
Cargo Proteins

We have identified a novel pathway for protein import into the nucleus. Although the product of Saccharomyces cerevisiae gene MSN5 was previously shown to function as a karyopherin (Kap) for nuclear export of various proteins, we discovered a nuclear import pathway mediated by Msn5p (also referred to as Kap142p). We have purified from yeast cytosol a complex containing Kap142p and the trimeric replication protein A (RPA), which is required for multiple aspects of DNA metabolism, including DNA replication, DNA repair, and recombination. In wild-type cells, RPA was localized primarily to the nucleus but, in a KAP142 deletion strain, RPA was mislocalized to the cytoplasm and the strain was highly sensitive to bleomycin (BLM). BLM causes DNA double-strand breaks and, in S. cerevisiae, the DNA damage is repaired predominantly by RPA-dependent homologous recombination. Therefore, our results indicate that in wild-type cells a critical portion of RPA was imported into the nucleus by Kap142p. Like several other import-related Kap–substrate complexes, the endogenous RPA–Kap142p complex was dissociated by RanGTP, but not by RanGDP. All three RPA genes are essential for viability, whereas KAP142 is not. Perhaps explaining this disparity, we observed an interaction between RPA and Kap95p in a strain lacking Kap142p. This interaction could provide a mechanism for import of RPA into the nucleus and cell viability in the absence of Kap142p. Together with published results (Kaffman, A., N.M. Rank, E.M. O'Neill, L.S. Huang, and E.K. O'Shea. 1998. Nature. 396:482–486; Blondel, M., P.M. Alepuz, L.S. Huang, S. Shaham, G. Ammerer, and M. Peter. 1999. Genes Dev. 13:2284–2300; DeVit, M.J., and M. Johnston. 1999. Curr. Biol. 9:1231–1241; Mahanty, S.K., Y. Wang, F.W. Farley, and E.A. Elion. 1999. Cell. 98:501–512) our data indicate that the karyopherin Kap142p is able to mediate nuclear import of one set of proteins and nuclear export of a different set of proteins.

scholarly journals The cohesin-like RecN protein stimulates RecA-mediated recombinational repair of DNA double-strand breaks

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Lee A. Uranga ◽  
Emigdio D. Reyes ◽  
Praveen L. Patidar ◽  
Lindsay N. Redman ◽  
Shelley L. Lusetti
Keyword(s):  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

scholarly journals Interleukin33 deficiency causes tau abnormality and neurodegeneration with Alzheimer-like symptoms in aged mice

2017 ◽  
Vol 7 (7) ◽  
pp. e1164-e1164 ◽  
Author(s):  
C Carlock ◽  
J Wu ◽  
J Shim ◽  
I Moreno-Gonzalez ◽  
M R Pitcher ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Memory Impairment ◽  
Middle Age ◽  
Late Onset ◽  
Double Strand Breaks ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Rapid Accumulation ◽  
Do So

Abstract Late-onset Alzheimer’s disease (AD) remains a medical mystery. Recent studies have linked it to impaired repair of aged neurons. Potential involvement of interleukin33 (IL33) in AD has been reported. Here we show that IL33, which was expressed by up to 75% astrocytes in the aged brains, was critical for repair of aged neurons. Mice lacking Il33 gene (Il33 −/− ) developed AD-like disease after 60–80 weeks, which was characterized by tau abnormality and a heavy loss of neurons/neurites in the cerebral cortex and hippocampus accompanied with cognition/memory impairment. We detected an abrupt aging surge in the cortical and hippocampal neurons at middle age (40 weeks). To counter the aging surge, wild-type mice rapidly upregulated repair of DNA double-strand breaks (DSBs) and autophagic clearance of cellular wastes in these neurons. Il33 −/− mice failed to do so, but instead went on to develop rapid accumulation of abnormal tau, massive DSBs and abnormal autophagic vacuoles in these neurons. Thus, uncontrolled neuronal aging surge at middle age due to lack of IL33 resulted in neurodegeneration and late-onset AD-like symptome in Il33 −/− mice. Our study also suggests that the aging surge is a time to search for biomarkers for early diagnosis of AD before massive neuron loss.

scholarly journals Nonhomologous end-joining of site-specific but not of radiation-induced DNA double-strand breaks is reduced in the presence of wild-type p53

Oncogene ◽  
2005 ◽  
Vol 24 (10) ◽  
pp. 1663-1672 ◽  
Author(s):  
Jochen Dahm-Daphi ◽  
Petra Hubbe ◽  
Fruzsina Horvath ◽  
Raafat A El-Awady ◽  
Katie E Bouffard ◽  
...  
Keyword(s):  
Double Strand Breaks ◽  
Nonhomologous End Joining ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Site Specific ◽  
Strand Breaks ◽  
Radiation Induced ◽  
Wild Type P53

scholarly journals Mdt1 Facilitates Efficient Repair of Blocked DNA Double-Strand Breaks and Recombinational Maintenance of Telomeres

2007 ◽  
Vol 27 (18) ◽  
pp. 6532-6545 ◽  
Author(s):  
Brietta L. Pike ◽  
Jörg Heierhorst
Keyword(s):  
Dna Recombination ◽  
Double Strand Breaks ◽  
Telomere Maintenance ◽  
Type I ◽  
Dna Double Strand Breaks ◽  
Drug Induced ◽  
Exogenous Dna ◽  
Strand Breaks ◽  
Dramatic Shift ◽  
Recombination Pathway

ABSTRACT DNA recombination plays critical roles in DNA repair and alternative telomere maintenance. Here we show that absence of the SQ/TQ cluster domain-containing protein Mdt1 (Ybl051c) renders Saccharomyces cerevisiae particularly hypersensitive to bleomycin, a drug that causes 3′-phospho-glycolate-blocked DNA double-strand breaks (DSBs). mdt1Δ also hypersensitizes partially recombination-defective cells to camptothecin-induced 3′-phospho-tyrosyl protein-blocked DSBs. Remarkably, whereas mdt1Δ cells are unable to restore broken chromosomes after bleomycin treatment, they efficiently repair “clean” endonuclease-generated DSBs. Epistasis analyses indicate that MDT1 acts in the repair of bleomycin-induced DSBs by regulating the efficiency of the homologous recombination pathway as well as telomere-related functions of the KU complex. Moreover, mdt1Δ leads to severe synthetic growth defects with a deletion of the recombination facilitator and telomere-positioning factor gene CTF18 already in the absence of exogenous DNA damage. Importantly, mdt1Δ causes a dramatic shift from the usually prevalent type II to the less-efficient type I pathway of recombinational telomere maintenance in the absence of telomerase in liquid senescence assays. As telomeres resemble protein-blocked DSBs, the results indicate that Mdt1 acts in a novel blocked-end-specific recombination pathway that is required for the efficiency of both drug-induced DSB repair and telomerase-independent telomere maintenance.

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