Matrix attachment region regulates basal beta-lactoglobulin transgene expression

Nuclear matrix attachment regions (MAR) have been implicated in the regulat ion of gene expression. We have identified a region within the proximal 3'- flanking sequences of the ovine beta-lactoglobulin (beta lg) gene that inte racts with the nuclear matrix in vitro. No equivalent region was detected i n the 5' flanking region. We have investigated the role of this element in regulating beta lg expression in vitro and in vivo. Removal of the MAR did not affect the frequency of beta lg transgene expression at the mRNA level, but beta lg transgenes that lacked the MAR were expressed at a lower level than wild-type beta lg transgenes. In neither in-vitro HC11 transfection e xperiments nor transgenic mice was hormonal induction of beta lg expression significantly affected by MAR removal. Nuclear run-on analysis demonstrate d that the impaired basal expression of beta lg transgene loci lacking the MAR was due to a reduced transcription rate. Thus, the single MAR enhances the basal transcriptional potential of the beta lg gene. (C) 2000 Elsevier Science B.V. All rights reserved.