title: Position-independent expression of whey acidic protein transgenes.
abstract: The expression of a 3-kilobase genomic rat whey acidic protein (WAP) clone (-949/+2020) in transgenic mice has been demonstrated previously to be copy number-dependent and independent of the site of integration (Dale, T., Krnacik, M. J., Schmidhauser, C., Yang, C. Q.-L., Bissell, M. J., and Rosen, J. M. (1992) Mol. Cell. Biol. 12, 905-914). The present study demonstrated that position-independent expression of the rat WAP -949/+2020 transgene was dependent on transgene spacing. Position-independent expression also was inhibited by an internal replacement of 49 base pair within the conserved GC-rich 3'-untranslated region (3'-UTR) with an identically sized nonspecific DNA sequence. Using electrophoretic mobility shift assays, nuclear factors isolated from mouse and human cells were shown to associate specifically with the rWAP 3'-UTR DNA, but not with the 3'-UTR containing the internal replacement or specific point mutations. Since a single copy of the 3'-UTR inserted 5' of the promoter could not rescue the 3'-UTR deletion, the 3'-UTR element does not appear to be functioning as either a classic enhancer or insulator element. However, the level of expression of rWAP transgenes was correlated with transgene association with the chromosomal scaffold in vivo.
authors.affiliation: Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Krnacik
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Liao
authors.forename: J M
authors.initials: JM
authors.lastname: Rosen
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002467:Cell Nucleus / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis; D017931:DNA Primers; D005091:Exons; D005260:Female; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D008321:Mammary Glands, Animal / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008894:Milk Proteins / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D017931:DNA Primers; D008894:Milk Proteins; D012333:RNA, Messenger; C024471:whey acidic proteins; D004247:DNA