scholarly journals H. pylori infection inhibits autophagy to aggravate DNA damage by p62-mediated Rad51 ubiquitination

2019 ◽  
Author(s):  
Chuan Xie ◽  
Nianshuang Li ◽  
Huan Wang ◽  
Cong He ◽  
Yi Hu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Direct Interaction ◽  
Gastric Carcinogenesis ◽  
Mongolian Gerbils ◽  
Dependent Manner ◽  
Gastric Intestinal Metaplasia ◽  
Uba Domain ◽  
Tumorigenic Transformation ◽  
Infected Cells ◽  
H Pylori

AbstractHelicobacter pylori (H. pylori) infection is the strongest known risk factor for gastric carcinogenesis. DNA damage response (DDR) and autophagy play key roles in tumorigenic transformation. However, it remains unclear how H. pylori infection modulate DNA damage and autophagy. Here we report that H. pylori infection promotes DNA damage via suppression of Rad51 expression through inhibition of autophagy and accumulation of p62 in gastric carcinogenesis. We find that H. pylori infection caused alteration of DDR pathway and autophagy in gastric cells and Mongolian gerbils in a CagA-dependent manner. Moreover, loss of autophagy led to promotion of DNA damage in H. pylori-infected cells. Furthermore, knockdown of autophagic substrate p62 upregulated Rad51 expression, and p62 promoted ubiquitination of Rad51 via the direct interaction of the UBA domain with Rad51. Finally, H. pylori infection was associated with elevated levels of p62 in gastric intestinal metaplasia and decreased levels of Rad51 in dysplasia compared to their H. pylori- counterparts. Our findings provide a novel mechanism into the linkage of H. pylori infection, autophagy, DNA damage and gastric tumorigenesis.

Reduced apoptosis in H. pylori-associated gastric intestinal metaplasia: A factor in gastric carcinogenesis?

1998 ◽  
Vol 114 ◽  
pp. A676 ◽  
Author(s):  
IA Scotiniotis ◽  
T Rokkas ◽  
EE Furth ◽  
JW Plotkin ◽  
B Rigas ◽  
...  
Keyword(s):  
Intestinal Metaplasia ◽  
Gastric Carcinogenesis ◽  
Gastric Intestinal Metaplasia ◽  
H Pylori

scholarly journals Helicobacter pylori induces intracellular galectin-8 aggregation around damaged lysosomes within gastric epithelial cells in a host O-glycan-dependent manner

Glycobiology ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 151-162 ◽  
Author(s):  
Fang-Yen Li ◽  
I-Chun Weng ◽  
Chun-Hung Lin ◽  
Mou-Chieh Kao ◽  
Ming-Shiang Wu ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Rhesus Macaques ◽  
Dependent Manner ◽  
Gastric Epithelial Cells ◽  
Vacuolating Cytotoxin ◽  
Infected Cells ◽  
H Pylori ◽  
Autophagy Activity ◽  
Binding Lectin

Abstract Galectin-8, a beta-galactoside-binding lectin, is upregulated in the gastric tissues of rhesus macaques infected with Helicobacter pylori. In this study, we found that H. pylori infection triggers intracellular galectin-8 aggregation in human-derived AGS gastric epithelial cells, and that these aggregates colocalize with lysosomes. Notably, this aggregation is markedly reduced following the attenuation of host O-glycan processing. This indicates that H. pylori infection induces lysosomal damage, which in turn results in the accumulation of cytosolic galectin-8 around damaged lysosomes through the recognition of exposed vacuolar host O-glycans. H. pylori-induced galectin-8 aggregates also colocalize with autophagosomes, and galectin-8 ablation reduces the activation of autophagy by H. pylori. This suggests that galectin-8 aggregates may enhance autophagy activity in infected cells. We also observed that both autophagy and NDP52, an autophagy adapter, contribute to the augmentation of galectin-8 aggregation by H. pylori. Additionally, vacuolating cytotoxin A, a secreted H. pylori cytotoxin, may contribute to the increased galectin-8 aggregation and elevated autophagy response in infected cells. Collectively, these results suggest that H. pylori promotes intracellular galectin-8 aggregation, and that galectin-8 aggregation and autophagy may reciprocally regulate each other during infection.

scholarly journals Epidermal growth factor receptor inhibition downregulates Helicobacter pylori-induced epithelial inflammatory responses, DNA damage and gastric carcinogenesis

Gut ◽  
2017 ◽  
Vol 67 (7) ◽  
pp. 1247-1260 ◽  
Author(s):  
Johanna C Sierra ◽  
Mohammad Asim ◽  
Thomas G Verriere ◽  
M Blanca Piazuelo ◽  
Giovanni Suarez ◽  
...  
Keyword(s):  
Dna Damage ◽  
Epidermal Growth Factor Receptor ◽  
Epithelial Cells ◽  
Growth Factor Receptor ◽  
Inflammatory Cells ◽  
Gastric Carcinogenesis ◽  
Gastric Epithelial Cells ◽  
Egfr Activation ◽  
Epidermal Growth ◽  
H Pylori

ObjectiveGastric cancer is the third leading cause of cancer death worldwide and infection by Helicobacter pylori is the strongest risk factor. We have reported increased epidermal growth factor receptor (EGFR) phosphorylation in the H. pylori-induced human carcinogenesis cascade, and association with DNA damage. Our goal was to determine the role of EGFR activation in gastric carcinogenesis.DesignWe evaluated gefitinib, a specific EGFR inhibitor, in chemoprevention of H. pylori-induced gastric inflammation and cancer development. Mice with genetically targeted epithelial cell-specific deletion of Egfr (EfgrΔepi mice) were also used.ResultsIn C57BL/6 mice, gefitinib decreased Cxcl1 and Cxcl2 expression by gastric epithelial cells, myeloperoxidase-positive inflammatory cells in the mucosa and epithelial DNA damage induced by H. pylori infection. Similar reductions in chemokines, inflammatory cells and DNA damage occurred in infected EgfrΔepi versus Egfrfl/fl control mice. In H. pylori-infected transgenic insulin-gastrin (INS-GAS) mice and gerbils, gefitinib treatment markedly reduced dysplasia and carcinoma. Gefitinib blocked H. pylori-induced activation of mitogen-activated protein kinase 1/3 (MAPK1/3) and activator protein 1 in gastric epithelial cells, resulting in inhibition of chemokine synthesis. MAPK1/3 phosphorylation and JUN activation was reduced in gastric tissues from infected wild-type and INS-GAS mice treated with gefitinib and in primary epithelial cells from EfgrΔepi versus Egfrfl/fl mice. Epithelial EGFR activation persisted in humans and mice after H. pylori eradication, and gefitinib reduced gastric carcinoma in INS-GAS mice treated with antibiotics.ConclusionsThese findings suggest that epithelial EGFR inhibition represents a potential strategy to prevent development of gastric carcinoma in H. pylori-infected individuals.

scholarly journals Poly(ADP-ribose)-dependent chromatin unfolding facilitates the association of DNA-binding proteins with DNA at sites of damage

2019 ◽  
Vol 47 (21) ◽  
pp. 11250-11267 ◽  
Author(s):  
Rebecca Smith ◽  
Théo Lebeaupin ◽  
Szilvia Juhász ◽  
Catherine Chapuis ◽  
Ostiane D’Augustin ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Binding ◽  
Chromatin Remodeling ◽  
Direct Interaction ◽  
Dna Lesions ◽  
Dependent Manner ◽  
Binding Domains ◽  
Damage Response ◽  
Direct Binding ◽  
Dnase Hypersensitivity

Abstract The addition of poly(ADP-ribose) (PAR) chains along the chromatin fiber due to PARP1 activity regulates the recruitment of multiple factors to sites of DNA damage. In this manuscript, we investigated how, besides direct binding to PAR, early chromatin unfolding events controlled by PAR signaling contribute to recruitment to DNA lesions. We observed that different DNA-binding, but not histone-binding, domains accumulate at damaged chromatin in a PAR-dependent manner, and that this recruitment correlates with their affinity for DNA. Our findings indicate that this recruitment is promoted by early PAR-dependent chromatin remodeling rather than direct interaction with PAR. Moreover, recruitment is not the consequence of reduced molecular crowding at unfolded damaged chromatin but instead originates from facilitated binding to more exposed DNA. These findings are further substantiated by the observation that PAR-dependent chromatin remodeling at DNA lesions underlies increased DNAse hypersensitivity. Finally, the relevance of this new mode of PAR-dependent recruitment to DNA lesions is demonstrated by the observation that reducing the affinity for DNA of both CHD4 and HP1α, two proteins shown to be involved in the DNA-damage response, strongly impairs their recruitment to DNA lesions.

scholarly journals Biphasic Functional Interaction between the Adenovirus E4orf4 Protein and DNA-PK

2019 ◽  
Vol 93 (10) ◽  
Author(s):  
Keren Nebenzahl-Sharon ◽  
Hassan Shalata ◽  
Rakefet Sharf ◽  
Jana Amer ◽  
Hanan Khoury-Haddad ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Virus Replication ◽  
Dna Damage Response ◽  
Late Phase ◽  
Direct Interaction ◽  
Dependent Manner ◽  
Functional Interaction ◽  
Cancer Cell Death ◽  
Damage Response

ABSTRACTThe adenovirus (Ad) E4orf4 protein contributes to virus-induced inhibition of the DNA damage response (DDR) by reducing ATM and ATR signaling. Consequently, E4orf4 inhibits DNA repair and sensitizes transformed cells to killing by DNA-damaging drugs. Inhibition of ATM and ATR signaling contributes to the efficiency of virus replication and may provide one explanation for the cancer selectivity of cell death induced by the expression of E4orf4 alone. In this report, we investigate a direct interaction of E4orf4 with the DDR. We show that E4orf4 physically associates with the DNA-dependent protein kinase (DNA-PK), and we demonstrate a biphasic functional interaction between these proteins, wherein DNA-PK is required for ATM and ATR inhibition by E4orf4 earlier during infection but is inhibited by E4orf4 as infection progresses. This biphasic process is accompanied by initial augmentation and a later inhibition of DNA-PK autophosphorylation as well as by colocalization of DNA-PK with early Ad replication centers and distancing of DNA-PK from late replication centers. Moreover, inhibition of DNA-PK improves Ad replication more effectively when a DNA-PK inhibitor is added later rather than earlier during infection. When expressed alone, E4orf4 is recruited to DNA damage sites in a DNA-PK-dependent manner. DNA-PK inhibition reduces the ability of E4orf4 to induce cancer cell death, likely because E4orf4 is prevented from arriving at the damage sites and from inhibiting the DDR. Our results support an important role for the E4orf4–DNA-PK interaction in Ad replication and in facilitation of E4orf4-induced cancer-selective cell death.IMPORTANCESeveral DNA viruses evolved mechanisms to inhibit the cellular DNA damage response (DDR), which acts as an antiviral defense system. We present a novel mechanism by which the adenovirus (Ad) E4orf4 protein inhibits the DDR. E4orf4 interacts with the DNA damage sensor DNA-PK in a biphasic manner. Early during infection, E4orf4 requires DNA-PK activity to inhibit various branches of the DDR, whereas it later inhibits DNA-PK itself. Furthermore, although both E4orf4 and DNA-PK are recruited to virus replication centers (RCs), DNA-PK is later distanced from late-phase RCs. Delayed DNA-PK inhibition greatly contributes to Ad replication efficiency. When E4orf4 is expressed alone, it is recruited to DNA damage sites. Inhibition of DNA-PK prevents both recruitment and the previously reported ability of E4orf4 to kill cancer cells. Our results support an important role for the E4orf4–DNA-PK interaction in Ad replication and in facilitation of E4orf4-induced cancer-selective cell death.

scholarly journals Adenovirus Replaces Mitotic Checkpoint Controls

2015 ◽  
Vol 89 (9) ◽  
pp. 5083-5096 ◽  
Author(s):  
Roberta L. Turner ◽  
Peter Groitl ◽  
Thomas Dobner ◽  
David A. Ornelles
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Tumor Suppressor ◽  
Adenovirus Type ◽  
Cyclin B1 ◽  
Mitotic Checkpoint ◽  
Mitotic Catastrophe ◽  
Dependent Manner ◽  
Infected Cells ◽  
Adenoviral Proteins

ABSTRACTInfection with adenovirus triggers the cellular DNA damage response, elements of which include cell death and cell cycle arrest. Early adenoviral proteins, including the E1B-55K and E4orf3 proteins, inhibit signaling in response to DNA damage. A fraction of cells infected with an adenovirus mutant unable to express the E1B-55K and E4orf3 genes appeared to arrest in a mitotic-like state. Cells infected early in G1of the cell cycle were predisposed to arrest in this state at late times of infection. This arrested state, which displays hallmarks of mitotic catastrophe, was prevented by expression of either the E1B-55K or the E4orf3 genes. However, E1B-55K mutant virus-infected cells became trapped in a mitotic-like state in the presence of the microtubule poison colcemid, suggesting that the two viral proteins restrict entry into mitosis or facilitate exit from mitosis in order to prevent infected cells from arresting in mitosis. The E1B-55K protein appeared to prevent inappropriate entry into mitosis through its interaction with the cellular tumor suppressor protein p53. The E4orf3 protein facilitated exit from mitosis by possibly mislocalizing and functionally inactivating cyclin B1. When expressed in noninfected cells, E4orf3 overcame the mitotic arrest caused by the degradation-resistant R42A cyclin B1 variant.IMPORTANCECells that are infected with adenovirus type 5 early in G1of the cell cycle are predisposed to arrest in a mitotic-like state in a p53-dependent manner. The adenoviral E1B-55K protein prevents entry into mitosis. This newly described activity for the E1B-55K protein appears to depend on the interaction between the E1B-55K protein and the tumor suppressor p53. The adenoviral E4orf3 protein facilitates exit from mitosis, possibly by altering the intracellular distribution of cyclin B1. By preventing entry into mitosis and by promoting exit from mitosis, these adenoviral proteins act to prevent the infected cell from arresting in a mitotic-like state.

scholarly journals Effect of Vietnamese Helicobactor pylori strain DN18 on the NF-κB pathway and H2AX activation of the AGS cell line

2020 ◽  
Vol 4 (2) ◽  
pp. First
Author(s):  
Dao Thi Hong Pham ◽  
Trang My Ho Nguyen ◽  
Vy Thuy Nguyen
Keyword(s):  
Molecular Mechanisms ◽  
Target Genes ◽  
Strand Break ◽  
Gastric Carcinogenesis ◽  
Mucosal Cell ◽  
Geographical Regions ◽  
Infected Cells ◽  
H Pylori ◽  
The Impact

Infection with Helicobacter pylori (H. pylori) is the strongest known risk factor for gastric cancer. The molecular mechanisms of H. pylori-associated gastric carcinogenesis remain not elucidated. Recent findings indicate that H. pylori infection may promote gastric carcinogenesis by inducing inflammation and genetic instability in gastric epithelial cells. In addition, it is shown that the impact of H. pylori on infected cells is associated with bacterial virulence that is diverse among geographical regions as well as populations. Therefore, we aimed to investigate the effect of H. pylori strain DN18 from Vietnamese subject on the in vitro activity of NF-κB transcription factor, a key regulator of inflammation, and expression of its target genes in this study. Moreover, host genomic instabilities were studied through examining the formation of DNA double-strand break (DSB) by using phosphorylated histone H2AX (γH2AX) as a DSB marker. Our results showed that H. pylori strain DN18 induced activation of NF-kB pathway and increased transcriptional expression of inflammatory mediators in human gastric mucosal cell AGS. We also provided evidence that the H. pylori infection triggered accumulation of  DSBs marker γH2AX. In summary, our study showed the potential ability to cause inflammation and DNA damage to infected cells of H. pylori strains isolated from Vietnamese patients.

A Role for Splicing Factors and the Transcriptional Machinery in the Pathophysiology of Fanconi Anemia,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3443-3443
Author(s):  
Allison M Green ◽  
James B Wilson ◽  
Nigel J Jones ◽  
Gary M. Kupfer
Keyword(s):  
Dna Damage ◽  
Fanconi Anemia ◽  
Genetic Disorder ◽  
Direct Interaction ◽  
Congenital Defects ◽  
Splicing Factors ◽  
Dependent Manner ◽  
Protein Levels ◽  
Transcriptional Machinery ◽  
In Cells

Abstract Abstract 3443 Introduction: Fanconi anemia(FA) is an autosomal and X-linked recessive genetic disorder characterized by congenital defects, aplastic anemia, and a predisposition to cancer. At the cellular level, patients with FA display hypersensitivity to DNA crosslinking agents and increased levels of chromosomal instability. Because of these cellular phenotypes, the FA pathway has been thought to function in DNA damage repair response. Our data suggest that one of the ways in which the FA pathway maintains genomic stability within cells is by preventing aberrant transcription following DNA damage. This regulation may be accomplished through a connection to splicing factors or through direct interaction with the transcriptional machinery itself (RNAPII). Methods: siRNA transfections were used to reduce protein levels of splicing factors. Survival assays were performed to determine cell sensitivity to mitomycin C (MMC). Chromatin extractions were performed to determine chromatin loading of proteins. Immunoprecipitations were used to determine protein-protein interactions. Results: Previous studies in our lab have shown that siRNA mediated knock down of the splicing factors ASF/SF2 and SC35 but not SRp55 result in decreased levels of FANCD2 ubiquitylation following MMC treatment and hypersensitivity to MMC. We have since shown that depletion of ASF/SF2 and SC35 but not SRp55 also prevents proper FANCD2 chromatin loading following MMC treatment. As depletion of the splicing factor ASF/SF2 has also been demonstrated to increase cellular genomic instability through the formation of increased levels of R-loop structures, we next wanted to determine what effects increased levels of RNaseH would have on activation of the FA pathway in cells with decreased ASF/SF2 expression. Interestingly, RNaseH overexpression was able to partially rescue the decreased levels of FANCD2 ubiquitylation following MMC treatment and hypersensitivity to MMC seen in cells with decreased protein levels of ASF/SF2. As splicing has been shown to occur co-transcriptionally, we next went on to determine whether transcription occurs normally in cells lacking an intact FA pathway. We discovered that proper degradation of the hyperphosphorylated, transcription competent form of RNAPII in response to DNA damage is dependent upon an intact FA pathway as cells mutant in FANCA or FANCD2 show delayed RNAPII degradation following MMC treatment. Accordingly, we also saw a decrease in the levels of RNAPII interacting with FANCD2 in chromatin after similar, short term MMC treatments. This was accompanied by FANCD2 interaction with RNAPII and BARD1 in a FANCD2 ubiquitylation-dependent manner. Conclusions: These results suggest that the FA pathway may play a part in regulating transcription via a connection to splicing factors and through direct interaction with the transcriptional machinery itself as a means of initiating the DNA damage response. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Oxidative DNA damage accumulation in gastric carcinogenesis

Gut ◽  
1998 ◽  
Vol 42 (3) ◽  
pp. 351-356 ◽  
Author(s):  
F Farinati ◽  
R Cardin ◽  
P Degan ◽  
M Rugge ◽  
F Di Mario ◽  
...  
Keyword(s):  
Dna Damage ◽  
Free Radical ◽  
Disease Activity ◽  
Atrophic Gastritis ◽  
Intestinal Metaplasia ◽  
Oxidative Dna Damage ◽  
Multiple Logistic Regression Analysis ◽  
Gastric Carcinogenesis ◽  
Indirect Measure ◽  
H Pylori

Background—Gastric carcinogenesis is a multifactorial, multistep process, in which chronic inflammation plays a major role.Aims—In order to ascertain whether free radical mediated oxidative DNA damage is involved in such a process, concentrations of 8-hydroxydeoxyguanosine (8OHdG), a mutagenic/carcinogenic adduct, and thiobarbituric acid reactive substances (TBARS), as an indirect measure of free radical mediated damage, were determined in biopsy specimens from patients undergoing endoscopy.Patients—Eighty eight patients were divided into histological subgroups as follows: 27 with chronic non-atrophic gastritis, 41 with atrophic gastritis, six with gastric cancer, and 14 unaffected controls.Methods—Intestinal metaplasia,Helicobacter pylori infection, and disease activity were semiquantitatively scored. 8OHdG concentrations were assessed by HPLC with electrochemical detection, and TBARS concentrations were fluorimetrically assayed.Results—8OHdG concentrations (mean number of adducts/105 dG residues) were significantly higher in chronic atrophic gastritis (p=0.0009). Significantly higher concentrations were also detected in the presence of severe disease activity (p=0.02), intestinal metaplasia (p=0.035), and H pylori infection (p=0.001). TBARS concentrations were also higher in atrophic gastritis, though not significantly so. In a multiple logistic regression analysis, 8OHdG concentrations correlated best with the presence and severity of H pylori infection (r=0.53, p=0.002).Conclusions—Chronic gastritis is characterised by the accumulation of oxidative DNA damage with mutagenic and carcinogenic potential. H pylori infection is the major determinant for DNA adduct formation.

scholarly journals Helicobacter pylori-Induced Signaling Pathways Contribute to Intestinal Metaplasia and Gastric Carcinogenesis

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Soichiro Sue ◽  
Wataru Shibata ◽  
Shin Maeda
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Atrophic Gastritis ◽  
Intestinal Metaplasia ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Gastric Carcinogenesis ◽  
Dependent Manner ◽  
Intracellular Signaling Pathways ◽  
H Pylori

Helicobacter pylori(H. pylori) induces chronic gastric inflammation, atrophic gastritis, intestinal metaplasia, and cancer. Although the risk of gastric cancer increases exponentially with the extent of atrophic gastritis, the precise mechanisms of gastric carcinogenesis have not been fully elucidated.H. pyloriinduces genetic and epigenetic changes in gastric epithelial cells through activating intracellular signaling pathways in a cagPAI-dependent manner.H. pylorieventually induces gastric cancer with chromosomal instability (CIN) or microsatellite instability (MSI), which are classified as two major subtypes of gastric cancer. Elucidation of the precise mechanisms of gastric carcinogenesis will also be important for cancer therapy.

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