Gene correction of the apolipoprotein (apo) E2 phenotype to wild-type apoE3 by in situ chimeraplasty

Apolipoprotein (apo) E is a polymorphic plasma protein, synthesized mainly by liver. Here, we evaluate whether synthetic DNA-RNA oligonucleotides (chi meraplasts) can convert a dysfunctional isoform, apoE2 (C --> T, R158C), wh ich causes Type III hyperlipidemia and premature atherosclerosis, into apoE 3. First, we treated recombinant Chinese hamster ovary cells stably secreti ng apoE2 with a 68-mer apoE2 to apoE3 chimeraplast. About one-third of apoE 2 was converted to apoE3, and the repair was stable through 12 passages. Su bcloning treated cells produced both apoE2 and apoE3 clones. Direct sequenc ing and reverse transcription polymerase chain reaction confirmed the genot ype, whereas phenotypic change was verified by isoelectric focusing and imm unoblotting of secreted proteins. Second, we established that the APOE2 gen e can be targeted both in vivo, using transgenic mice overexpressing human apoE2, and in chromosomal context, using cultured lymphocytes from a patien t homozygous for the epsilon2 allele. We conclude that chimeraplasty has th e potential to convert the apoE2 mutation in patients with Type III hyperli pidemia to apoE3.