A widespread family of heat-resistant obscure (Hero) proteins protect against protein instability and aggregation
(A) Representative images of aggregation in human iPS-derived motor neurons transfected with GFP-TDP-43ΔNLS, together with the GST negative control or Hero7. Note that signals from aggregations are saturated. (B) Scheme for counting the saturated area of TDP-43ΔNLS aggregates. (C) Aggregation index analysis in motor neurons. GFP-TDP-43ΔNLS was expressed in motor neurons, together with each Hero protein or the GST negative control. Data indicate normalized saturated area (aggregation index), and represent means ± SD from 3 independent experiments. Hero9, -45, -7, and -11 reduced the aggregate formation. (D) Neurite length analysis in motor neurons. Each Hero protein or the GST control was individually expressed in motor neurons. Data indicate neurite length, and represent means ± SD from 8 cells. Hero45 showed a modest defect in neurite outgrowth. (E) Representative images of the neuron marker TUJ1 in motor neurons transfected with GFP-TDP-43ΔNLS, together with Hero7 or the GST control. Note that signals are saturated to clearly visualize the neurites. (F) Neurite length quantification in motor neurons transfected with GFP-TDP-43ΔNLS together with each Hero protein or the GST negative control. Data indicate neurite length, and represent means ± SD from 8 cells. Hero9, -7 and -11 rescued the neurite outgrowth defect by GFP-TDP-43ΔNLS aggregation. The numerical data pertaining to this figure can be found in S1 Data file. GFP, green fluorescence protein; GST, glutathione S-transferase; Hero, heat-resistant obscure; iPS, induced-pluripotent stem; TDP-43ΔNLS, TDP-43 lacking the nuclear localization signal; TUJ1, neuron-specific class III beta-tublin.