Figure 2.

PTMs can be expressed in human HD iPSC-derived NPCs. (A) Overlays of GFP and bright-field live images of HD or control NPCs after infection with lentivirus. Uninfected cells do not express GFP. Cells infected with PTM-encoding lentivirus have GFP expression in the majority of cells. White scale bar length represents 100 μm. (B) HD and control iPSC-derived NPCs infected with PTM-encoding lentivirus express the predicted high molecular weight HTT (indicated by chevron) as well as a specific low molecular weight N-terminal HTT fragment (indicated by arrow). Actin was used as an internal loading control. HD and control iPSC-derived NPCs infected with PTM-encoding lentivirus express two detectible isoforms of GFP via Western blotting. The lower molecular weight band corresponds to the expected size for GFP (indicated by arrowhead), whereas the higher molecular weight band is at the same size as the band found in the PTM-expressing cells via an anti-HTT antibody (indicated by arrow). Huntingtin (EM48) gave an additional a non-specific band (found in both + and – PTM) around 37 kDa (^* indicates non-specific bands). (C) Filter trap assay detects that HD and control iPSC-derived NPCs infected with PTM-encoding lentivirus have more polyQ aggregation. The lower right lane (thick outside border) was loaded with lysis buffer only to serve as a negative control. (D) NPCs derived from HD and control iPSCs express similar levels and localization of HTT and β3-tubulin/TUJ1 (an immature neuron marker) regardless of presence of PTM (indicated by expression of GFP). White scale bar length represents 50 μm.