title: Control of expression and methylation of a hepatitis B virus transgene by strain-specific modifiers.
abstract: In transgenic animals, genotype-specific modifiers exert a control over transgene methylation and expression that may or may not be position dependent. These factors belong to different classes, some of them possibly related to modifiers of position-effect variegation in Drosophila. The study of hepatitis B virus (HBV) gene expression in transgenic mice has revealed the existence of many factors influencing transcription, including hormones and tissue-specific transcription factors. We now report the effect of genotype-specific modifiers on HBV surface antigen (HBsAg) expression and transgene methylation. Compared with the C57BL/6 background, the DBA/2 and 129sv backgrounds cause enhancement of HBsAg expression, with little or not effect on transgene methylation or transcription. In contrast, a single cross with a BALB/c mouse is responsible for de novo methylation and silencing of the transgene in all offspring. Several modifiers appear to segregate in the progeny of a transgenic E36 male mouse crossed with (C57BL/6 x BALB/c) F1 females, with the emergence of a high-expressor group. Our observations suggest that different modifiers act cooperatively, at both the transcriptional and post-transcriptional levels, as part of a complex system regulating transgene expression. This transgenic model provides a system to genetically map new mouse strain-specific modifiers, some of them involved in epigenetic modification and transcription control.
authors.affiliation: UREG Institut Pasteur, Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Schweizer
authors.forename: P
authors.initials: P
authors.lastname: Valenza-Schaerly
authors.forename: F
authors.initials: F
authors.lastname: Goret
authors.forename: C
authors.initials: C
authors.lastname: Pourcel
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D019175:DNA Methylation; D005260:Female; D015967:Gene Expression Regulation, Viral; D006514:Hepatitis B Surface Antigens / Q000096:biosynthesis; D006515:Hepatitis B virus / Q000235:genetics*; D008099:Liver / Q000737:chemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D013045:Species Specificity; D019076:Transgenes
chemical_list: D006514:Hepatitis B Surface Antigens