title: Substitution of the alpha-lactalbumin transcription unit by a CAT cDNA within a BAC clone silenced the locus in transgenic mice without affecting the physically linked Cyclin T1 gene.
abstract: We recently reported that a goat bacterial artificial chromosome (BAC) clone conferred site-independent expression in transgenic mice of the two loci present within its insert, the ubiquitously expressed Cyclin T1 and the mammary specific alpha-lactalbumin (alphalac) genes. To assess if this vector could target mammary-restricted expression of cDNA, the CAT ORF was introduced by homologous recombination in Escherichia coli in place of the alphalac transcription unit. The insert of this modified BAC was injected into mice and three transgenic lines were derived. None of these lines expressed the CAT gene suggesting that the use of long genomic inserts is not sufficient to support the expression of intron-less transgenes. The physically linked goat Cyclin T1 locus was found to be active in all three lines. This observation reinforced the hypothesis that the two loci are localised in two separate chromatin domains.
authors.affiliation: Laboratoire de génétique biochimique et de cytogénétique, Département de génétique animale, Institut national de la recherche agronomique, 78352 Jouy-en-Josas Cedex, France.
authors.forename: Solange
authors.initials: S
authors.lastname: Soulier
authors.forename: Marthe
authors.initials: M
authors.lastname: Hudrisier
authors.forename: José Costa
authors.initials: JC
authors.lastname: Da Silva
authors.forename: Caroline
authors.initials: C
authors.lastname: Maeder
authors.forename: Céline
authors.initials: C
authors.lastname: Viglietta
authors.forename: Nathalie
authors.initials: N
authors.lastname: Besnard
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Vilotte
mesh_terms: D000818:Animals; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics*; D056906:Cyclin T; D016213:Cyclins / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D020868:Gene Silencing; D007768:Lactalbumin / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic
chemical_list: C503685:Ccnt1 protein, mouse; D056906:Cyclin T; D016213:Cyclins; D017931:DNA Primers; D007768:Lactalbumin