Chicken beta-globin insulator overcomes variegation of transgenes in Xenopus embryos.
Chromatin structure and gene transcription regulation are intimately linked, and mosaic expression of randomly integrated transgenes into the genome is frequently observed. This variegation of transgene expression is likely due to the genomic integration site, which can affect the behavior of the integrated DNA sequence in a positive or a negative way. Insulators are a class of DNA elements that can protect genes from inappropriate signals emanating from their environment by acting as boundaries that prevent the spreading of nearby condensed chromatin that may otherwise silence expression. Here we show that transgenes escape this silencing in Xenopus laevis and Xenopus tropicalis embryos and that a stable, uniform, and heritable expression pattern is obtained when transgenes are flanked with tandem copies of the chicken beta-globin 5'HS4 insulator. Our data also indicate that the insulator confers copy-number-dependent transgene expression and can increase transgene expression from weak regulatory elements. Hence, it will be an invaluable tool for generating stable lines expressing different levels of a particular coding sequence.
Sekkali
Belaïd
B
Department for Molecular Biomedical Research, VIB-Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
Tran
Hong Thi
HT
Crabbe
Ellen
E
De Beule
Christophe
C
Van Roy
Frans
F
Vleminckx
Kris
K
D000818:Animals; D030801:Animals, Genetically Modified / Q000502:physiology*; D002645:Chickens; D002843:Chromatin / Q000235:genetics / Q000648:ultrastructure; D017931:DNA Primers; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005786:Gene Expression Regulation; D014644:Genetic Variation; D005914:Globins / Q000235:genetics*; D038101:Insulator Elements / Q000235:genetics*; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014981:Xenopus / Q000196:embryology*
D002843:Chromatin; D017931:DNA Primers; D005914:Globins