Fig. 1: Lin28 and YB-1 colocalize in cells and mix along microtubules, in contrast to G3BP-1, HuR, or FUS.

a Left panel: Detection scheme of the microtubule bench assay. Right panel: YB-1 used as bait (in red) and 4 RNA-binding proteins (RBPs) used as preys (in green) were co-expressed in HeLa cells. The bait is brought onto microtubules owing to its fusion to a microtubule-binding domain (MBD). The presence of a prey on microtubules therefore reveals a bait/prey interaction. Scale bar: 15 µm and 4 µm (higher magnification, right panel). b Upper panel: Spearman’s coefficient reflecting the presence of the prey on microtubules was measured at the single cell level (n = 20) for 4 different baits and 4 different preys, as indicated. Lower panel: Interaction score for indicated preys and baits measured by extrapolating the Spearman’s coefficient for very low bait expression level (see Materials and Methods). Values are given with 95 % confidence bounds. c Two RBPs as indicated are confined on the microtubule network (fused to RFP/GFP-MBD) to visualize their mixing/demixing in HeLa cells. Mixing: yellow microtubules. Demixing: red and green microtubules. Scale bars: 15 µm and 4 µm (higher magnification, left panel). d Upper panel: Representative images for Proximity Ligation Assays (PLA) between GFP and endogenous YB-1 in HeLa cells expressing indicated proteins GFP, LARP6-GFP and Lin28-GFP. Lower panel: PLA signal versus the expression levels of indicated proteins at the single cell level (GFP integrated intensity, n > 100). Scale bar: 15 µm.