Human BAC-mediated rescue of the Friedreich ataxia knockout mutation in transgenic mice.
Three independent transgenic mouse lines were generated with the human Friedreich ataxia gene, FRDA, in an 188-kb bacterial artificial chromosome (BAC) genomic sequence. Three copies of the transgene per diploid mouse genome were integrated in a single site in each mouse line. Transgenic mice were mated with mice heterozygous for a knockout mutation of the murine Frda gene, to generate mice homozygous for the Frda knockout mutation and hemizygous or homozygous for the human transgene. Rescue of the embryonic lethality that is associated with homozygosity for the Frda knockout mutation was observed in all three lines. Rescued mice displayed normal behavioral and biochemical parameters. RT-PCR analysis demonstrated that human FRDA mRNA is expressed in all the lines. The relative expression of the human FRDA and mouse Frda genes showed a similar pattern in different tissues in all three lines, indicating position-independent control of expression of the human FRDA transgene. However, large differences in the human:mouse mRNA ratio were observed between different tissues in all three lines. The human transgene is expressed at much higher levels in the brain, liver, and skeletal muscle than the endogenous gene, while expression of the human transgene in blood is only 25-30% of the mouse gene. These studies will facilitate the development of humanized mouse models of Friedreich ataxia through introduction of a GAA trinucleotide expansion or specific known point mutations in the normal human FRDA locus and the study of the regulation of gene expression from the FRDA locus.
Sarsero
Joseph P
JP
Cell and Gene Therapy Research Group, Murdoch Childrens Research Institute, University of Melbourne Department of Pediatrics, Royal Children's Hospital, Flemington Road, 3052, Melbourne, VIC, Australia.
Li
Lingli
L
Holloway
Timothy P
TP
Voullaire
Lucille
L
Gazeas
Sophie
S
Fowler
Kerry J
KJ
Kirby
Denise M
DM
Thorburn
David R
DR
Galle
Adam
A
Cheema
Surindar
S
Koenig
Michel
M
Williamson
Robert
R
Ioannou
Panos A
PA
D000818:Animals; D022202:Chromosomes, Artificial, Bacterial; D005260:Female; D005621:Friedreich Ataxia / Q000235:genetics* / Q000503:physiopathology*; D018628:Gene Dosage; D005804:Genes, Lethal; D005816:Genetic Complementation Test; D006720:Homozygote; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008124:Locomotion; D008297:Male; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics*; D008822:Mice, Transgenic / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019076:Transgenes / Q000502:physiology
D012333:RNA, Messenger