A postimplantation lethal mutation induced by transgene insertion on mouse chromosome 8.
We have produced three lines of transgenic mice that contain additional copies of the mouse phosphoglycerate kinase 1 (Pgk1) gene. Two of these lines, 94-A and 94-K, which are descendants of a common founder, did not produce liveborn progeny carrying two copies of these transgenes (i.e., A/A, K/K, or A/K). Genotyping of midgestation embryos showed that A/K embryos are dead by Embryonic Day 10. Comparison of the level of transgene expression in the three transgenic lines ruled out PGK1 toxicity as the cause of death of A/A, A/K, and K/K embryos. The death of A/A, K/K, and A/K transgenic mice was therefore attributed to an insertional mutation disrupting a gene or genes essential for normal embryogenesis. Analysis of the structure of the 94-A and 94-K transgenes indicated that they differ in the number of tandem repeats and in the positions of the transgene-cellular DNA junctions. To determine if the two transgenes represent a single integration followed by a rearrangement or two independent integration events, we cloned the endogenous sequences surrounding the 94-A and 94-K transgene insertion sites. Restriction analysis of the isolated genomic clones indicated that the endogenous sequences abutting the 3' ends of the 94-A and 94-K transgenes are separated by less than 20 kb, providing strong support for the single integration model. Further analysis indicated that the 94-A transgene is associated with a deletion of at least 18 kb and is located in the vicinity of a widely transcribed endogenous gene. Chromosomal mapping of the endogenous sequences flanking the 94-A and 94-K transgene insertions using mouse-hamster somatic cell hybrids and a (C57BL/6J x SPRET/Ei)F1 x SPRET/Ei backcross panel allowed us to assign the 94-A(K) transgene insertion to the subcentral region of mouse chromosome 8.
Pravtcheva
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Department of Pediatrics, Saint Louis University School of Medicine, Missouri 63110, USA.
Wise
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D000818:Animals; D002874:Chromosome Mapping; D002875:Chromosomes; D003001:Cloning, Molecular; D006224:Cricetinae; D003433:Crosses, Genetic; D005260:Female; D015870:Gene Expression; D005804:Genes, Lethal / Q000235:genetics*; D006720:Homozygote; D007621:Karyotyping; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016254:Mutagenesis, Insertional; D010735:Phosphoglycerate Kinase / Q000235:genetics*; D013997:Time Factors; D014158:Transcription, Genetic; D019076:Transgenes / Q000235:genetics*
D010735:Phosphoglycerate Kinase