Transient posterior localization of a kinesin fusion protein reflects anteroposterior polarity of the Drosophila oocyte.
BACKGROUND
During oogenesis in Drosophila, determinants that will dictate abdomen and germline formation are localized to the 'polar plasm' in the posterior of the oocyte. Assembly of the polar plasm involves the sequential localization of several messenger RNAs and proteins to the posterior of the oocyte, beginning with the localization of oskar mRNA and Staufen protein during stages 8 and 9 of oogenesis. The mechanism by which these two early components accumulate at the posterior is not known. We have investigated whether directed transport along microtubules could be used to accomplish this localization.


RESULTS
We have made a fusion protein composed of the bacterial beta-galactosidase enzyme as a reporter, joined to part of the plus-end-directed microtubule motor, kinesin, and have found that the fusion protein transiently localizes to the posterior of the oocyte during stages 8 and 9 of oogenesis. Treatment with the microtubule-depolymerizing agent colchicine prevents both the localization of the fusion protein and the posterior transport of oskar mRNA and Staufen protein. Furthermore, the fusion protein localizes normally in oocytes mutant for either oskar and staufen, but not in other mutants in which oskar mRNA and Staufen protein are mislocalized.


CONCLUSIONS
Association with a plus-end-directed microtubule motor can promote posterior localization of a reporter protein during oogenesis. The genetic requirements for this localization and its sensitivity to colchicine, both of which are shared with the posterior transport of oskar mRNA and Staufen protein, suggest that similar mechanism may function in both processes.
Clark
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I
Howard Hughes Medical Institute, University of California at San Francisco 94143-0724.
Giniger
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E
Ruohola-Baker
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H
Jan
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LY
Jan
Y N
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D016764:Cell Polarity; D003078:Colchicine / Q000494:pharmacology; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D005260:Female; D017344:Genes, Insect; D017930:Genes, Reporter; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics
D011993:Recombinant Fusion Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D001616:beta-Galactosidase; D016547:Kinesins; D003078:Colchicine