In response to stress, mammalian cells halt the translation of mRNA, and instead form stress granules – mRNA-containing cytoplasmic foci that harbour abortive initiation complexes. Stress granules are in dynamic equilibrium with translating polysomes – but how is stress-granule assembly regulated? On page 563, Graciela Boccaccio and colleagues establish a role for Staufen 1 (a polysome-associated RNA-binding protein) in the dissolution of stress granules. Using several cell types, the authors show that Stau1 is recruited to stress granules when cells are subjected to ER stress or oxidative stress. Stau1 is not, however, an essential component of stress granules, which still form in Stau1-depleted cells. The authors note that knocking down Stau1 promotes stress-dependent granule formation, but that this granule formation is impaired when a construct encoding Stau1 is transfected. They show that the N-terminal half of Stau1 is responsible for this inhibitory capacity. Finally, the authors observe that polysomes that remain following stress induction are enriched in Stau1. They propose, therefore, that Stau1 helps to stabilise polysomes, tipping the polysome–stress-granule balance in favour of granule dissolution. These results help to clarify how the cellular stress response can be modulated.
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