The H. pylori CagA Oncoprotein Induces DNA Double Strand Breaks through Fanconi Anemia Pathway Downregulation and Replication Fork Collapse.
Int J Mol Sci
; 23(3)2022 Jan 31.
Article
em En
| MEDLINE
| ID: mdl-35163588
ABSTRACT
The proteins from the Fanconi Anemia (FA) pathway of DNA repair maintain DNA replication fork integrity by preventing the unscheduled degradation of nascent DNA at regions of stalled replication forks. Here, we ask if the bacterial pathogen H. pylori exploits the fork stabilisation machinery to generate double stand breaks (DSBs) and genomic instability. Specifically, we study if the H. pylori virulence factor CagA generates host genomic DSBs through replication fork destabilisation and collapse. An inducible gastric cancer model was used to examine global CagA-dependent transcriptomic and proteomic alterations, using RNA sequencing and SILAC-based mass spectrometry, respectively. The transcriptional alterations were confirmed in gastric cancer cell lines infected with H. pylori. Functional analysis was performed using chromatin fractionation, pulsed-field gel electrophoresis (PFGE), and single molecule DNA replication/repair fiber assays. We found a core set of 31 DNA repair factors including the FA genes FANCI, FANCD2, BRCA1, and BRCA2 that were downregulated following CagA expression. H. pylori infection of gastric cancer cell lines showed downregulation of the aforementioned FA genes in a CagA-dependent manner. Consistent with FA pathway downregulation, chromatin purification studies revealed impaired levels of Rad51 but higher recruitment of the nuclease MRE11 on the chromatin of CagA-expressing cells, suggesting impaired fork protection. In line with the above data, fibre assays revealed higher fork degradation, lower fork speed, daughter strands gap accumulation, and impaired re-start of replication forks in the presence of CagA, indicating compromised genome stability. By downregulating the expression of key DNA repair genes such as FANCI, FANCD2, BRCA1, and BRCA2, H. pylori CagA compromises host replication fork stability and induces DNA DSBs through fork collapse. These data unveil an intriguing example of a bacterial virulence factor that induces genomic instability by interfering with the host replication fork stabilisation machinery.
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Texto completo:
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Bases de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Transdução de Sinais
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Regulação para Baixo
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Helicobacter pylori
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Infecções por Helicobacter
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Proteínas Oncogênicas
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Replicação do DNA
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Proteínas de Grupos de Complementação da Anemia de Fanconi
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Quebras de DNA de Cadeia Dupla
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Antígenos de Bactérias
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Int J Mol Sci
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Singapura