July 1, 2004;
Xenopus Staufen is a component of a ribonucleoprotein complex containing Vg1 RNA and kinesin.
RNA localization is a key mechanism for generating cell and developmental polarity in a wide variety of organisms. We have performed studies to investigate a role for the Xenopus homolog of the double-stranded RNA-binding protein, Staufen
, in RNA localization during oogenesis. We have found that Xenopus Staufen
) is present in a ribonucleoprotein complex, and associates with both a kinesin motor protein and vegetally localized RNAs Vg1
. A functional role for XStau
was revealed through expression of a dominant-negative version that blocks localization of Vg1
RNA in vivo. Our results suggest a central role for XStau
in RNA localization in Xenopus oocytes, and provide evidence that Staufen
is a conserved link between specific mRNAs and the RNA localization machinery.
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Fig. 3. Distribution of XStau during oogenesis. Immunofluorescence was performed using XStau antibodies and Alexa-568 conjugated secondary antibody to detect the distribution of XStau in oocytes of the following stages: (A) stages I-II, (B) stages III-IV and (C) stages V-VI (Dumont, 1972). Confocal images are shown. Scale bars: 100 μm. Arrowheads show enrichment of XStau in the vegetal cortex of stage III-V oocytes.
Fig. 4. XStau and Vg1 RNA are colocalized in Xenopus oocytes. (A-D) Stage III-IV oocytes were microinjected with Alexa-546 labeled VLE RNA, followed by immunofluorescence using XStau antibodies and Alexa-647 secondary antibodies. (A) Localization of endogenous XStau, shown in red. (B) Injected VLE RNA, shown in green. (C) Colocalization of endogenous XStau and injected VLE RNA, digitally represented in white. (D) High-magnification image of the oocyte shown in C. (E) High-magnification image of the oocyte shown in A. (F) Distribution of XStau in vegetal hemisphere of an uninjected stage III oocyte, determined by immunofluorescence using XStau antibodies and Alexa-568-conjugated secondary antibodies. For all panels, representative confocal sections are shown. Scale bars: 20 μm.
stau1 (staufen, RNA binding protein, homolog 1) gene expression in Xenopus laevis oocyte IV, assayed via immunhistochemistry.