Staufen2 isoforms localize to the somatodendritic domain of neurons and interact with different organelles.
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.
Duchaîne
Thomas F
TF
Department of Biochemistry, University of Montreal, Montreal, H3C 3J7, Canada.
Hemraj
Indradeo
I
Furic
Luc
L
Deitinghoff
Anke
A
Kiebler
Michael A
MA
DesGroseillers
Luc
L
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002458:Cell Fractionation; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D015388:Organelles / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D016415:Sequence Alignment
D000906:Antibodies; D003598:Cytoskeletal Proteins; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C492185:STAU1 protein, human; C471844:STAU2 protein, human; C492187:Stau1 protein, mouse; C492186:Stau1 protein, rat; C492188:Stau2 protein, rat; C471845:stau2 protein, mouse; C117884:staufen protein, mammalian