Co-transfer of restriction endonucleases and plasmid DNA into mammalian cells by electroporation: effects on stable transformation.

We co-transferred cloned HSV thymidine kinase gene and restriction endonucleases, HindIII, XbaI, or XhoI, into thymidine kinase-deficient mouse LtK- cells by electroporation. Stimulation of the transformation efficiency was observed with HindIII or XbaI, while little effect was observed with XhoI. The stimulation was observed for various forms of exogenous DNA (linear or circular plasmid DNA and single-stranded phage DNA) and correlated with the number of strand breaks in the host-cell DNA. These results suggest that the presence of DNA double-strand breaks stimulates the integration of exogenous DNA into host cell genomes.