Using the novel RADR mouse to visualize the effects of age and environment on DNA repair in vivo in multiple tissues

Abstract

Homologous recombination (HR) is a DNA repair process that is critical for maintaining genomic integrity. HR is necessary for survival of vertebrate cells, but over‐ or under‐utilization of HR can lead to deleterious rearrangements and cancer. To study HR in vivo, we created the RADR (Rosa26 Direct Repeat) mouse that has enabled study of HR in a variety of tissues. The RADR mouse harbors two truncated EGFP genes integrated in the Rosa26 locus. Repair via HR at the substrate can yield a full‐length EGFP gene, resulting in a fluorescent cell. The frequency of HR can be estimated by flow cytometry or visualized in situ. The RADR mouse enables studies of DNA damage and repair in response to endogenous and exogenous factors in multiple tissues, which has never before been possible. We observed the accumulation of recombinant cells in the colon, liver and pancreas with age; this correlates with our understanding of age as a risk factor for cancer. We have also crossed the RADR mice with GPT‐Δ mice, enabling quantification of point mutations and small deletions. We crossed these mice with Rag2−/− mice allowing the study of sequence changes with enhanced innate immune response. In ongoing studies, we are investigating the impact of environmentally induced inflammation on susceptibility to large‐scale sequence rearrangements, point mutations and small deletions in multiple tissues. This work is supported by the NCI, NIEHS, NSF GRF.Grant Funding Source: NSF GRF, NCI, NIEHS