Fig. 3: PolyU modulates hnRNPA1A condensation and amyloid formation in a concentration-dependent manner.
From: RNA modulates hnRNPA1A amyloid formation mediated by biomolecular condensates
a, The change in volume of the hnRNPA1A dense phase at a fixed bulk concentration as measured by turbidity (OD400, the optical density at 400 nm) in the presence of increasing polyU concentrations. Turbidity measurements were performed in technical triplicates (n = 3) and with two distinct protein preparations, yielding similar results. b, Bright-field microscopy images showing the absence and presence of protein condensates at different polyU concentrations and constant protein concentration after 30 min of incubation. Accordingly, we delineate three different regimes: (1) condensation driven by homotypic interactions; (2) condensation driven by both homotypic and heterotypic protein–RNA interactions; and (3) re-entrant phase and absence of condensation. The regimes are colour-coded in all figures by purple, blue and green colours, respectively. Bright-field imaging was always performed in parallel with turbidity measurements to confirm the presence of condensates, and was therefore repeated for two different protein preparations. c,d, Raw and normalized ThT profiles of hnRNPA1A at increasing concentrations of polyU. The experiment was performed with three protein batches, each with three technical replicates. e, Half-times of hnRNPA1A aggregation kinetics calculated from the normalized curves shown in d as a function of polyU concentration (n = 3). f, Re-scan confocal microscopy images of end-point samples (48 h), using ThT as fluorophore. Fibrils are rearranged in a circular shape resembling the structure of the condensates only in the absence or at a very low concentration of polyU. Confocal imaging was performed for each condition at the end of the aggregation reaction to visualize fibrils, and was repeated for two different protein preparations.
