HUMAN APOLIPOPROTEIN-B TRANSGENIC MICE GENERATED WITH 207-KILOBASE AND 145-KILOBASE PAIR BACTERIAL ARTIFICIAL CHROMOSOMES - EVIDENCE THAT ADISTANT 5'-ELEMENT CONFERS APPROPRIATE TRANSGENE EXPRESSION IN THE INTESTINE

We reported previously that similar to 80-kilobase pair (kb) P1 bacter iophage clones spanning either the human or mouse apoB gene (clones p1 58 and p649, respectively) confer apoB expression in the liver of tran sgenic mice, but not in the intestine, We hypothesized that the absenc e of intestinal expression was due to the fact that these clones lacke d a distant DNA element controlling intestinal expression, To test thi s possibility, transgenic mice were generated with 145- and 207-kb bac terial artificial chromosomes (BACs) that contained the human apoB gen e and more extensive 5'- and 3'-flanking sequences, RNase protection, in situ hybridization, immunohistochemical, and genetic complementatio n studies revealed that the BAC transgenic mice manifested appropriate apoB gene expression in both the intestine and the liver, indicating that both BACs contained the distant intestinal element, To determine whether the regulatory element was located 5' or 3' to the apoB gene, transgenic mice were generated by co-microinjecting embryos with p158 and either the 5'- or 3'-sequences from the 145-kb BAG. Analysis of th ese mice indicated that the apoB gene's intestinal element is located 5' to the structural gene, Cumulatively, the transgenic mouse studies suggest that the intestinal element is located between -33 and -70 kb 5' to the apoB gene.