INVESTIGADORES
MARTINEZ TOSAR Leandro Julian
congresos y reuniones científicas
Título:
Staufen 1 and 2 are Recruited into Stress Granules in Mammalian Cells
Autor/es:
L. J. MARTÍNEZ TOSAR, M. G. THOMAS, M. LOSCHI, M. A. DESBATS, S. KINDLER, J. CORREALE, G. L. BOCCACCIO
Lugar:
Washington DC, EEUU
Reunión:
Conferencia; 44th Annual Meeting of the American Society for Cell Biology; 2004
Resumen:
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Staufen is
a double-stranded RNA-binding protein involved in mRNA cytoplasmic transport in
D.melanogaster oocytes and embryos, and in Xenopus oocytes. Two mammalian
Staufen orthologues have been described, which are thought to participate in
mRNA localization in neurons. We and others showed that mammalian Staufen 1 and
2 form granules in oligodendrocyte myelinating processes and in neuronal
dendrites. Staufen 1 and 2 are quite ubiquitous proteins which are present in
granules uniformly distributed throughout the cytoplasm in primary fibroblasts
and cell lines. Biochemical analysis revealed that both proteins associate to
polysomes and cytoskeletal components. Here we show that cellular stress or
drug-induced polysome disruption provokes a dramatic change of Staufen 1 and 2
distribution. Upon stress, normal Staufen granules coalesce into perinuclear
accretions of 5-10 μm. These structures contain polyadenilated RNA
-as indicated by PABP staining- and are reminiscent of stress granules (SG). SG
are large cytoplasmic RNPs formed during stress (UV, heat shock, oxidative
conditions, polysome disruption), and are thought to transiently store
housekeeping mRNAs in a silent state, while translation of stress-induced
transcripts is activated. Under oxidative stress or heat shock, Staufen
granules colocalize with TIAR and HuR, two RNA-binding proteins which normally
reside in the cell nucleus, but shuttle to the cytoplasm during the stress
response to form SG. Furthermore, Staufen stress granules contain small -but
not large- ribosomal subunits, another landmark of SG. Finally, stress-induced
Staufen granules remain attached to a Triton-resistant fraction, suggesting
interaction with cytoskeletal components. Our results suggest a putative role
for Staufen in the re-localization of polysomal mRNAs upon certain stimuli and
in particular, during the cellular stress response.
