title: The opportunistic pathogen Pseudomonas aeruginosa activates the DNA double-strand break signaling and repair pathway in infected cells.
abstract: Highly hazardous DNA double-strand breaks can be induced in eukaryotic cells by a number of agents including pathogenic bacterial strains. We have investigated the genotoxic potential of Pseudomonas aeruginosa, an opportunistic pathogen causing devastating nosocomial infections in cystic fibrosis or immunocompromised patients. Our data revealed that infection of immune or epithelial cells by P. aeruginosa triggered DNA strand breaks and phosphorylation of histone H2AX (γH2AX), a marker of DNA double-strand breaks. Moreover, it induced formation of discrete nuclear repair foci similar to gamma-irradiation-induced foci, and containing γH2AX and 53BP1, an adaptor protein mediating the DNA-damage response pathway. Gene deletion, mutagenesis, and complementation in P. aeruginosa identified ExoS bacterial toxin as the major factor involved in γH2AX induction. Chemical inhibition of several kinases known to phosphorylate H2AX demonstrated that Ataxia Telangiectasia Mutated (ATM) was the principal kinase in P. aeruginosa-induced H2AX phosphorylation. Finally, infection led to ATM kinase activation by an auto-phosphorylation mechanism. Together, these data show for the first time that infection by P. aeruginosa activates the DNA double-strand break repair machinery of the host cells. This novel information sheds new light on the consequences of P. aeruginosa infection in mammalian cells. As pathogenic Escherichia coli or carcinogenic Helicobacter pylori can alter genome integrity through DNA double-strand breaks, leading to chromosomal instability and eventually cancer, our findings highlight possible new routes for further investigations of P. aeruginosa in cancer biology and they identify ATM as a potential target molecule for drug design.
authors.affiliation: CEA, DSV, iRTSV-BCI, INSERM, UMR-S 1036, Biologie Du Cancer Et de L'Infection, CNRS, ERL 5261, Bacterial Pathogenesis and Cellular Responses, UJF-Grenoble 1, Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Elsen
authors.forename: Véronique
authors.initials: V
authors.lastname: Collin-Faure
authors.forename: Xavier
authors.initials: X
authors.lastname: Gidrol
authors.forename: Claudie
authors.initials: C
authors.lastname: Lemercier
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001427:Bacterial Toxins / Q000378:metabolism*; D045744:Cell Line, Tumor; D043171:Chromosomal Instability; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D018922:HL-60 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D015398:Signal Transduction; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; C468783:H2AX protein, human; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; D036002:ADP Ribose Transferases; C444820:exoenzyme S; D064007:Ataxia Telangiectasia Mutated Proteins; D048031:JNK Mitogen-Activated Protein Kinases