Site-directed mutagenesis by gene targeting in mouse embryo-derived stem cells.
We mutated, by gene targeting, the endogenous hypoxanthine phosphoribosyl transferase (HPRT) gene in mouse embryo-derived stem (ES) cells. A specialized construct of the neomycin resistance (neor) gene was introduced into an exon of a cloned fragment of the Hprt gene and used to transfect ES cells. Among the G418r colonies, 1/1000 were also resistant to the base analog 6-thioguanine (6-TG). The G418r, 6-TGr cells were all shown to be Hprt- as the result of homologous recombination with the exogenous, neor-containing, Hprt sequences. We have compared the gene-targeting efficiencies of two classes of neor-Hprt recombinant vectors: those that replace the endogenous sequence with the exogenous sequence and those that insert the exogenous sequence into the endogenous sequence. The targeting efficiencies of both classes of vectors are strongly dependent upon the extent of homology between exogenous and endogenous sequences. The protocol described herein should be useful for targeting mutations into any gene.
Thomas
K R
KR
Department of Biology, University of Utah, Salt Lake City 84112.
Capecchi
M R
MR
D000818:Animals; D001755:Blastocyst / Q000201:enzymology*; D002478:Cells, Cultured; D004262:DNA Restriction Enzymes; D005796:Genes; D005822:Genetic Vectors; D006412:Hematopoietic Stem Cells / Q000201:enzymology*; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D009693:Nucleic Acid Hybridization
D007041:Hypoxanthine Phosphoribosyltransferase; D004262:DNA Restriction Enzymes