Position-independent expression of whey acidic protein transgenes

J Biol Chem. 1995 May 12;270(19):11119-29. doi: 10.1074/jbc.270.19.11119.


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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Blotting, Southern
  • Cell Nucleus / metabolism
  • Chromosome Mapping
  • Cloning, Molecular
  • DNA / analysis
  • DNA Primers
  • Exons
  • Female
  • Gene Expression*
  • HeLa Cells
  • Humans
  • Mammary Glands, Animal / metabolism
  • Mice
  • Mice, Transgenic
  • Milk Proteins / biosynthesis*
  • Milk Proteins / genetics
  • Molecular Sequence Data
  • Point Mutation
  • Polymerase Chain Reaction
  • Promoter Regions, Genetic
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / metabolism
  • Rats
  • Repetitive Sequences, Nucleic Acid


  • DNA Primers
  • Milk Proteins
  • RNA, Messenger
  • whey acidic proteins
  • DNA