Tg(APOE3*R224Q)1Her

This transgene resulted from random integration of a human APOE expression cassette encoding the E3 variant with an inadvertent mutation resulting in replacement of arginine by glutamine at amino acid position 224 (R224Q). The transgenic construct contained a mouse/human chimeric gene comprising 5.3 kb of strain 129 mouse genomic DNA upstream of the Apoe coding region, including exon 1 and the 5' 376 bp of intron 1; most of the human APOE3 variant allele, including the 3' 723 bp of intron 1, exons 2-4 containing the entire protein coding region, and 1.5 kb of 3'-flanking DNA; a neomycin resistance cassette; and a 1.4-kb mouse genomic fragment containing the 3' part of exon 4 and 3' flanking DNA. This construct was introduced into B6;129 fertilized oocytes. Western blot analysis of plasma and of liver lysates revealed similar levels of endogenous APOE protein in wild-type mice and of human APOE in mice homozygous for both the transgene and a null allele of Apoe (Apoetm1Unc), but hippocampal lysates from the latter mice contained barely detectable levels of human APOE; immunohistochemical analysis of hippocampal sections of transgenic/knockout brains using an anti-APOE antibody showed faint, diffuse interstitial staining, but no staining of cells. Thus, transgene-derived human APOE is expressed normally in the periphery, but is essentially absent in the brain. (J:41705, J:235715)