Mammalian Staufen 1 is recruited to stress granules and impairs their assembly

MARÍA GABRIELA THOMAS*, LEANDRO JULIÁN MARTINEZ TOSAR*, MARÍA ANDREA DESBATS*; CLAUDIA CARINA LEISHMAN, GRACIELA L. BOCCACCIO

JOURNAL OF CELL SCIENCE

Company of Biologists

Lugar: Inglaterra; Año: 2009 p. 563 - 573

0021-9533

Stress granules (SGs) are cytoplasmic mRNA silencing foci that form transientlyduring the stress response. SGs harbor abortive translation initiation complexes andare in dynamic equilibrium with translating polysomes. Mammalian Staufen 1 is aubiquitous double-stranded RNA-binding protein associated to polysomes. Here weshow that Staufen 1 is recruited to SGs upon induction of endoplasmic reticulum oroxidative stress, as well in SGs induced by translation initiation blockers. We foundthat SGs lacking Staufen 1 formed in cells depleted of this molecule, indicating thatStaufen 1 is not an essential component of SGs. Moreover, Staufen 1 knockdownfacilitated SG formation upon stress induction. Conversely, transient transfection ofStaufen 1 impaired SG formation upon stress or pharmacological initiation arrest.The inhibitory capacity of Staufen 1 mapped to the amino-terminal half of themolecule, a region known to bind to polysomes. Most polysomes are disrupted uponstress induction and we found that the fraction of remaining polysomes was enrichedin Staufen 1 and that Staufen 1 stabilized polysomes against stress. The blockage ofSG formation by Staufen 1 was partially released by pharmacological disruption ofpolysomes. We propose that Staufen 1 is involved in recovery from stress bystabilizing polysomes thus helping SG dissolution.