Visualizing homologous recombination and illustrating DNA repair pathway interaction in vivo via a bioengineered fluorescent reporter system

Abstract

Homologous recombination (HR) is a DNA repair process critical for maintaining genomic integrity. HR is generally beneficial, but over‐ or under‐utilization of HR can lead to can lead to deleterious rearrangements and cancer. To study HR, our laboratory previously developed the Fluorescent Yellow Direct Repeat (FYDR) mouse in which HR yields a fluorescent signal.We have utilized this mouse to study the interplay between HR and non‐homologous end‐joining (NHEJ) by knocking out the Ku86 protein. Both pathways are known to repair double strand breaks (DSB); preventing NHEJ in Ku86−/− mice resulted in an increase in HR. The newly proposed alternative end‐joining pathway was explored by knocking down the repair protein Ercc1. The Ercc1−/Δ mice showed an increase in HR in the pancreas, confirming in vivo an alternative DSB repair pathway and implicating ERCC1 in this pathway.While an excellent tool, the FYDR mouse is limited to study of HR in the pancreas and skin. We created the RADR (Recombination at a Direct Repeat) mouse, an improved model that has enabled our study of HR in a wide range of tissues including gut and liver. We can now study DNA damage and HR in multiple tissues in response to a treatment or exposure.Grant Funding Source : NIEHS Grant T32‐ES07020, NSF GRF, NIH Grant# P01‐CA026731‐31, R33‐CA112151‐01A2