CONICET | Buscador de Institutos y Recursos Humanos

Stress granules (SGs) are cytoplasmic mRNA silencing foci that form transiently during the stress response. SGs harbor abortive translation initiation complexes and are in dynamic equilibrium with translating polysomes. Mammalian Staufen 1 is a ubiquitous double-stranded RNA-binding protein associated to polysomes. Here we show that Staufen 1 is recruited to SGs upon induction of endoplasmic reticulum or oxidative stress as well in SGs induced by translation initiation blockers. We found that SGs lacking Staufen 1 formed in cells depleted of this molecule, indicating that Staufen 1 is not an essential component of SGs. Moreover, Staufen 1 knockdown facilitated SG formation upon stress induction. Conversely, transient transfection of Staufen 1 impaired SG formation upon stress or pharmacological initiation arrest. The inhibitory capacity of Staufen 1 mapped to the amino-terminal half of the molecule, a region known to bind to polysomes. We found that the fraction of polysomes remaining upon stress induction was enriched in Staufen 1, and that Staufen 1 overexpression stabilized polysomes against stress. We propose that Staufen 1 is involved in recovery from stress by stabilizing polysomes thus helping SG dissolution.