title: Deletion of p66Shc in mice increases the frequency of size-change mutations in the lacZ transgene.
abstract: Upon oxidative challenge the genome accumulates adducts and breaks that activate the DNA damage response to repair, arrest, or eliminate the damaged cell. Thus, reactive oxygen species (ROS) generated by endogenous oxygen metabolism are thought to affect mutation frequency. However, few studies determined the mutation frequency when oxidative stress is reduced. To test whether in vivo spontaneous mutation frequency is altered in mice with reduced oxidative stress and cell death rate, we crossed p66Shc knockout (p66KO) mice, characterized by reduced intracellular concentration of ROS and by impaired apoptosis, with a transgenic line harboring multiple copies of the lacZ mutation reporter gene as part of a plasmid that can be recovered from organs into Escherichia coli to measure mutation rate. Liver and small intestine from 2- to 24-month-old, lacZ (p66Shc+/+) and lacZp66KO mice, were investigated revealing no difference in overall mutation frequency but a significant increase in the frequency of size-change mutations in the intestine of lacZp66KO mice. This difference was further increased upon irradiation of mice with X-ray. In addition, we found that knocking down cyclophilin D, a gene that facilitates mitochondrial apoptosis acting downstream of p66Shc, increased the size-change mutation frequency in small intestine. Size-change mutations also accumulated in death-resistant embryonic fibroblasts from lacZp66KO mice treated with H2 O2 . These results indicate that p66Shc plays a role in the accumulation of DNA rearrangements and suggest that p66Shc functions to clear damaged cells rather than affect DNA metabolism.
authors.affiliation: Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, Milan, 20139, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Beltrami
authors.forename: Antonella
authors.initials: A
authors.lastname: Ruggiero
authors.forename: Rita
authors.initials: R
authors.lastname: Busuttil
authors.forename: Enrica
authors.initials: E
authors.lastname: Migliaccio
authors.forename: Pier Giuseppe
authors.initials: PG
authors.lastname: Pelicci
authors.forename: Jan
authors.initials: J
authors.lastname: Vijg
authors.forename: Marco
authors.initials: M
authors.lastname: Giorgio
mesh_terms: D000818:Animals; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005720:Gamma Rays; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D007763:Lac Operon; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D059645:Mutation Rate; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019076:Transgenes
chemical_list: D000081406:Peptidyl-Prolyl Isomerase F; C000631446:PPIF protein, mouse; D017382:Reactive Oxygen Species; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D006861:Hydrogen Peroxide; D021983:Cyclophilins