An EGFP reporter system to visualize homologous recombination in vivo

Abstract

The ability of cells to repair damaged DNA via homologous recombination (HR) is crucial to maintaining the fidelity of genomic information. While generally beneficial, HR can cause tumorgenic sequence rearrangements.Our laboratory has developed a method for measuring HR frequency in the mouse. The Fluorescent Yellow Direct Repeat (FYDR) mice harbor incomplete repeat copies of the EYFP coding sequence. In the event of HR repair at the substrate, a complete EYFP sequence can result, leading to a fluorescent cell visible via flow cytometry.In the FYDR mice, the EYFP substrate is not adequately expressed in all tissue types, preventing study of HR. To study previously inaccessible tissues, we have developed a new vector targeted at the ubiquitously expressed Rosa26 locus. We describe a new targeting vector consisting of tandem EGFP cassettes lacking essential sequences and initial characterization of the model.We will use this model for many studies, specifically genomic stability in tissues susceptible to inflammation‐induced cancer. Knowledge of the relationship between exposures and HR will help us identify key factors modulating cancer susceptibility. NSF GRF, NIH# P01‐CA26731, R33‐CA112151‐01A2Grant Funding Source: R33‐Ca112151‐01A2; NSF GRF, NIH Grant# P01‐CA26731