The localization of Oskar at the posterior pole of the Drosophila oocyte induces the assembly of the pole plasm and therefore defines where the abdomen and germ cells form in the embryo. This localization is achieved by the targeting of oskar mRNA to the posterior and the localized activation of its translation. oskar mRNA seems likely to be actively transported along microtubules, since its localization requires both an intact microtubule cytoskeleton and the plus end–directed motor kinesin I, but nothing is known about how the RNA is coupled to the motor. Here, we describe barentsz, a novel gene required for the localization of oskar mRNA. In contrast to all other mutations that disrupt this process, barentsz-null mutants completely block the posterior localization of oskar mRNA without affecting bicoid and gurken mRNA localization, the organization of the microtubules, or subsequent steps in pole plasm assembly. Surprisingly, most mutant embryos still form an abdomen, indicating that oskar mRNA localization is partially redundant with the translational control. Barentsz protein colocalizes to the posterior with oskar mRNA, and this localization is oskar mRNA dependent. Thus, Barentsz is essential for the posterior localization of oskar mRNA and behaves as a specific component of the oskar RNA transport complex.
Barentsz is essential for the posterior localization of oskar mRNA and colocalizes with it to the posterior pole
F.J.M. van Eeden and I.M. Palacios contributed equally to this work.
F.J.M. van Eeden's present address is The Hubrecht Laboratory, Uppsalalaan 8 3584CT, Utrecht, Netherlands.
M. Petronczki's present address is the Research Institute of Molecular Pathology, Dr. Bohr Gasse 7, A-1030 Vienna, Austria.
Abbreviations used in this paper: GFP, green fluorescent protein; RFLP, restriction fragment length polymorphism; UTR, untranslated region.
Fredericus J.M. van Eeden, Isabel M. Palacios, Mark Petronczki, Matthew J.D. Weston, Daniel St Johnston; Barentsz is essential for the posterior localization of oskar mRNA and colocalizes with it to the posterior pole . J Cell Biol 6 August 2001; 154 (3): 511–524. doi: https://doi.org/10.1083/jcb.200105056
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