Fig 1: Co-localization of Staufen1 with ATXN2 in stress-granule-like structures. a ATXN2 and STAU1 co-localize in SGs. Immunostaining of HEK-293 cells with antibodies against ATXN2, STAU1, and TIA-1 show co-localization of STAU1 with ATXN2 and TIA-1 in SGs during stress (0.5 mM sodium arsenite for 15 and 30 min) that are not present in the absence of stress. Scale bar, 10 µM. b Constitutively present SG-like structures positive for both ATXN2 and STAU1 in SCA2 FBs, but not in normal FBs (white arrows). Cells were stained with antibodies to ATXN2 and STAU1. Scale bar, 100 µM. c Increased numbers of aggregates in SCA2 FBs at 37 °C. Aggregates > 4 pixels per cell positive for both ATXN2 and STAU1 are shown. One-hundred normal and 96 SCA2-FBs were used for analyses. Data are mean ± SD, **P < 0.01, Student t-test. d Histograms representing the quantities and sizes of ATXN2-STAU1 co-localized granules in normal vs. SCA2 FBs. e In vivo co-localization of ATXN2 (green) with Stau1 (red) to aggregates in cerebellar PCs of 24-weeks-old ATXN2Q127 mice (white arrows). Scale bar, 30 µM. f Co-localized ATXN2 (red) and STAU1 (green) to aggregates (white arrows) in cerebellar PCs from a human SCA2 brain, that are absent in an unaffected control. Scale bar, 30 µM. g Immunoprecipitation of ATXN2 with STAU1. Non-RNase A or RNase A treated HEK-293 cell extracts expressing Flag-tagged ATXN2-(Q22 or Q108) were subjected to immunoprecipitation with Flag mAb beads and analyzed by western blotting. STAU1 shows RNA-dependent interactions with wild-type and mutant ATXN2. ATXN2 also co-immunoprecipitates with DDX6 and PABPC1, known ATXN2 interactors. Representative blots of three independent experiments are shown