T. Tsuzuki et al., TARGETED DISRUPTION OF THE RAD51 GENE LEADS TO LETHALITY IN EMBRYONICMICE, Proceedings of the National Academy of Sciences of the United Statesof America, 93(13), 1996, pp. 6236-6240
The mouse Rad51 gene is a mammalian homologue of the Escherichia coli
recA and yeast RAD51 genes, both of which are involved in homologous r
ecombination and DNA repair, To elucidate the physiological role of RA
D51 protein, the gene was targeted in embryonic stem (ES) cells, Mice
heterozygous for the Rad51 null mutation were inter-crossed and their
offspring were genotyped. There were no homozygous (Rad51(-1-)) pups a
mong 148 neonates examined but a few Rad51(-1-) embryos were identifie
d when examined during the early stages of embryonic development. Doub
ly knocked-out ES cells were not detected under conditions of selectiv
e growth. These results are interpreted to mean that RAD51 protein pla
ys an essential role in the proliferation of cell, The homozygous Rad5
1 null mutation can be categorized in cell-autonomous defects. Pre-imp
lantational lethal mutations that disrupt basic molecular functions wi
ll thus interfere with cell viability.