Chunk #18 — RESULTS — Reintroducing different apoE isoforms into apoE-deficient human neurons reveals a gain of toxic effects from apoE4 in hiPSC-derived apoE-null neurons
To further test the potential gain of toxicity conferred by apoE4, we transfected apoE−/− hiPSC-derived neurons with lentiviral cDNA constructs encoding apoE3 or apoE4. The transfected neurons expressed similar protein levels of apoE3 and apoE4 (Fig. 5h,i); however, those expressing apoE4 had higher p-tau levels (Fig. 5h,j) and fewer GABA-positive neurons (Fig. 5m,n) and produced more Aβ40 and Aβ42 (Fig. 5o,p) than neurons expressing apoE3 or controls (Fig. 5j–l, 5n–p). Interestingly, treating apoE−/− hiPSC-derived neurons with purified recombinant human apoE3 or apoE4 did not significantly alter Aβ production (Supplementary Fig. 10e,f), suggesting that the effect of apoE4 on Aβ production depends on the endogenous expression of apoE. Together, these findings strongly suggest that apoE4 confers a gain of toxic effects in hiPSC-derived neurons.
