title: Dissecting the role of N-myc in development using a single targeting vector to generate a series of alleles.
abstract: The N-myc proto-oncogene is expressed in many organs of the mouse embryo, suggesting that it has multiple functions. A null mutation leads to mid-gestation lethality [1-4], obscuring the later roles of the gene in organogenesis. We have generated a multi-purpose gene alteration by combining the potential for homologous and site-specific recombination in a single targeting vector, and using the selectable marker for neomycin-resistance, neo, to downregulate gene activity. This allowed us to create a series of alleles that led to different levels of N-myc expression. The phenotypes revealed a spectrum of developmental problems. The hypomorphic allele produced can be repaired in situ by Cre-recombinase-mediated DNA excision. We show here for the first time the use of a single targeting vector to generate an allelic series. This, and the possibility of subsequent lineage-specific or conditional allele repair in situ, represent new genome modification strategies that can be used to investigate multiple functions of a single gene.
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada. nagy@mshri.on.ca
authors.forename: A
authors.initials: A
authors.lastname: Nagy
authors.forename: C
authors.initials: C
authors.lastname: Moens
authors.forename: E
authors.initials: E
authors.lastname: Ivanyi
authors.forename: J
authors.initials: J
authors.lastname: Pawling
authors.forename: M
authors.initials: M
authors.lastname: Gertsenstein
authors.forename: A K
authors.initials: AK
authors.lastname: Hadjantonakis
authors.forename: M
authors.initials: M
authors.lastname: Pirity
authors.forename: J
authors.initials: J
authors.lastname: Rossant
mesh_terms: D000483:Alleles; D000818:Animals; D001483:Base Sequence; D000013:Congenital Abnormalities / Q000235:genetics; D004260:DNA Repair; D004274:DNA, Recombinant / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018390:Gene Targeting / Q000379:methods*; D016259:Genes, myc; D005822:Genetic Vectors; D006579:Heterozygote; D006720:Homozygote; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D009355:Neomycin / Q000494:pharmacology; D010641:Phenotype; D011247:Pregnancy
chemical_list: D004274:DNA, Recombinant; D009355:Neomycin