Alphavirus nsP3 ADP-ribosylhydrolase Activity Disrupts Stress Granule Formation

Aravinth Kumar Jayabalan; Diane E. Griffin; Anthony K. L. Leung

Formation of aberrant SGs is a hallmark of several neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) [1, 57] . Genetic mutations are commonly observed in RNA-binding proteins such as FUS (e.g. R495X), and overexpression of some ALS-related mutant RNA-binding proteins results in the formation of aggregates enriched in canonical SG components such as G3BP1 and translation initiation factors [58, 59] . We hypothesized that the formation of FUS R495X-mediated SG-like aggregates might also be suppressed by nsP3 ADPribosylhydrolase activity. We co-transfected FLAG-tagged FUS R495X with either GFP alone, GFPtagged nsP3 WT or GFP-nsP3 G32E into U2OS cells and examined the presence of FUS R495Xinduced aggregates. Consistent with previous reports [48, 49, 60] , overexpression of FUS-R495X itself formed SG-like aggregates, which were positive for G3BP1 and eIF3b, in ~50% of transfected cells (vector, Fig. 3c , e, data not shown). Intriguingly, co-transfection with full-length nsP3 WT, but not the point mutant G32E, decreased formation of these aggregates by two-fold (Fig. 3c, e) . Moreover, the All rights reserved. No reuse allowed without permission.