Huntingtin Polyglutamine-Dependent Protein Aggregation in Reconstituted Cells.

One of the aims of synthetic biology is bottom-up construction of reconstituted human cells for medical uses. To that end, we generated giant unilamellar vesicles (GUVs) that contained a HeLa cell extract, which comprises a cell-free protein synthesis (CFPS) system. Then we expressed Huntingtin protein fragments that contained polyglutamine (polyQ) sequences (Htt-polyQ), a hallmark of Huntington's disease. That system produced polyQ-dependent protein aggregates, as previously demonstrated in living cells. We next simplified the system by generating GUVs that contained purified human factors, which reconstituted a CFPS system. Htt-polyQ fragments expressed in these GUVs also formed protein aggregates. Moreover, an N-terminal deletion mutant, which had failed to form protein aggregates in living cells, also failed to form protein aggregates in the reconstituted GUVs. Thus, the GUV systems that encapsulated a human CFPS system could serve as reconstituted cells for studying neurological diseases.