DNA repair in murine embryonic stem cells and differentiated cells

Abstract

Embryonic stem (ES) cells are rapidly proliferating, self-renewing cells that have the capacity to differentiate into all three germ layers to form the embryo proper. Since these cells are critical for embryo formation, they must have robust prophylactic mechanisms to ensure that their genomic integrity is preserved. Indeed, several studies have suggested that ES cells are hypersensitive to DNA damaging agents and readily undergo apoptosis to eliminate damaged cells from the population. Other evidence suggests that DNA damage can cause premature differentiation in these cells. Several laboratories have also begun to investigate the role of DNA repair in the maintenance of ES cell genomic integrity. It does appear that ES cells differ in their capacity to repair damaged DNA compared to differentiated cells. This minireview focuses on repair mechanisms ES cells may use to help preserve genomic integrity and compares available data regarding these mechanisms with those utilized by differentiated cells.

Figure 1. γ-H2AX staining in ES cells and Mouse Embryo Fibroblasts (MEFs)

129/Sv derived ES cells (A, B) or passage 3 MEFs (C, D) were grown on coverslips in the absence (A, C) or presence (B, D) of 10µm etoposide for 4 or 6 hours. Cells were fixed and stained with γ-H2ax and nuclei were counterstained with draq5. Note the basal staining of γ-h2ax in ES cells (A). Scale bar represents 20 µm.

Figure 2. Endogenous protein expression levels of Rad51 and XRCC4 in MEFs and ES cells

SDS-PAGE was performed using 20 µg of 129/Sv ES cell or passage 3 MEF whole cell extracts and probed with the given antibodies.