FIGURE 1.

Biosensor platform to track Httex1 aggregation inside the cells and effect of aggregation on cell viability. A, schematic of the IRES vector system employed. The vector expresses Httex1^TC9, which is a biosensor of the Httex1 aggregation state that we previously showed can bind to the biarsenical dyes FlAsH or ReAsH when Httex1 is monomeric but not when it aggregates (17). Httex1^TC9 is fused to Cerulean as a marker to track Httex1 expression levels. Downstream the IRES sequence is the mKate2 fluorescent protein. We created two IRES versions, one with a farnesylation targeting sequence appended to the C terminus of mKate2 (mKate2-F) and another lacking this sequence (mKate2). B, expression and imaging of the IRES constructs in Neuro2a cells with derivatives of Httex1^TC9 containing different polyQ lengths. C, flow cytograms of Neuro2a cells transfected with the IRES vectors. Cells were pre-gated as indicated in Fig. 2. The gates L, M, and D were used for sorting, recovery, and visual inspection by microscopic imaging.