Fig. 5

DNAJB6b and DNAJB8 co-chaperones reduce poly-GA aggregate formation and increase its solubility. A The EGFP-poly-GA expression plasmid was co-transfected with expression plasmids for mCherry or selected chaperones and co-chaperones. Expression of DNAJB family proteins DNAJB6b and DNAJB8 strongly reduced the formation of cytoplasmic aggregates of poly-GA and caused its diffuse nucleocytoplasmic localization. (Scale bar: 50 µm; Hoechst DNA staining in blue). B Quantitative image analysis shows a decrease in the percentage of cells with poly-GA aggregates when DNAJB6b and DNAJB8 are co-expressed; n = 3, mean ± SD is shown. *p < 0.05, **p < 0.01 by Kruskal–Wallis test and Dunn’s multiple comparisons post-hoc test (number of post-hoc comparisons = 6). C Representative images of cells co-expressing DNAJB8 vs. mCherry show a shift from bright EGFP-positive foci to diffuse EGFP staining, indicating increased solubility of EGFP-poly-GA. Scale bar: 20 µm. D Filter trap assay (FTA, representative example) and E FTA quantification of poly-GA aggregates shows a reduction in detergent-insoluble poly-GA aggregates in lysates from cells co-transfected with DNAJB2a, DNAJB6b and DNAJB8; n = 3, mean ± SD is shown. *p < 0.05, **p < 0.01 by Kruskal–Wallis test and Dunn’s multiple comparisons post-hoc test (number of post-hoc comparisons = 6)