Staufen2 isoforms localize to the somatodendritic domain of neurons and interact with different organelles
2002
Mammalian Staufen2 (Stau2) is involved in mRNA transport in neurons. Here,
we report that Stau2 is a double-stranded RNA-binding protein that is mainly
expressed in the brain. We show that Stau2 is found in the somatodendritic
compartment of neurons. In dendrites, Stau2 is aligned on individual tracts
and colocalizes with microtubules. Stau2 is expressed as at least three splice
isoforms, which can be observed in several subcellular complexes. Although a
62 kDa isoform (Stau2 62 ) fractionates in ribosome-free fractions of
light density, Stau2 59 and Stau2 52 are found in
high-density complexes. These complexes are resistant to EDTA and to non-ionic
detergent. For the first time, we also provide evidence for an interaction of
some Stau2 isoforms with ribosomes, thus pointing to an interesting new role
for Stau2 in translation. EDTA treatment, which dissociates ribosome subunits,
does not release Stau2 from the subunits, suggesting that Stau2-ribosome
associations are not mediated mainly by mRNA intermediates. Although Stau2 has
many features in common with its paralogue Stau1, it does not colocalize with
Stau1-containing particles, indicating that these proteins are components of
different complexes in dendrites. Our findings suggest that members of the
Staufen family share evolutionarily conserved properties and highlight the
complexity of Staufen-mediated RNA transport in neurons.
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