The actin-binding protein Lasp promotes Oskar accumulation at the posterior pole of theDrosophilaembryo

Abstract

During Drosophila oogenesis, oskar mRNA is transported to the posterior pole of the oocyte, where it is locally translated and induces germ-plasm assembly. Oskar protein recruits all of the components necessary for the establishment of posterior embryonic structures and of the germline. Tight localization of Oskar is essential, as its ectopic expression causes severe patterning defects. Here, we show that the Drosophila homolog of mammalian Lasp1 protein, an actin-binding protein previously implicated in cell migration in vertebrate cell culture, contributes to the accumulation of Oskar protein at the posterior pole of the embryo. The reduced number of primordial germ cells in embryos derived from lasp mutant females can be rescued only with a form of Lasp that is capable of interacting with Oskar, revealing the physiological importance of the Lasp-Oskar interaction.

mRNA localization in theDrosophilagermline

“…23 At the posterior, the actin cytoskeleton, the actin binding proteins Lasp, Didum, Spire, Cappuccino, the Myosin-V motor, MTs and Dynein are all required for proper posterior accumulation and maintenance. [69][70][71][72][73][74][75] The involvement of both kinesin and Dynein in osk mRNA localization suggests that RNP particles are exposed to opposing directional forces during localization. How particles in vivo transition between plus and minus end movement remains unclear and an aim for future research.…”

A late phase of germ plasm accumulation during Drosophila oogenesis requires Lost and Rumpelstiltskin

“…Drosophila oogenesis can be divided into 14 morphologically defined stages, with nurse cell dumping occurring at the end of stage 10 (King, 1970). Microtubule-dependent transport of osk to the posterior of the oocyte occurs primarily during stage 9 and the mRNA is subsequently maintained at the posterior by a mechanism involving Osk protein and the actin cytoskeleton (Rongo et al, 1995;Babu et al, 2004;Vanzo et al, 2007;Suyama et al, 2009). In contrast to previously characterized mutants with osk localization defects, posterior localization of osk appears wild type in 100% of stage 9 egg chambers (n33) and 98% of stage 10 egg chambers (n52) (Fig.…”

Localization, anchoring and translational control ofoskar,gurken,bicoidandnanosmRNA during Drosophila oogenesis

“…Unlike initial posterior transport which depends on microtubules, osk mRNA anchoring requires the F-actin cytoskeleton as well as a number of F-actin-associated proteins. [41][42][43][44] Furthermore, long Osk is required for osk mRNA anchoring as osk mRNA detaches from the posterior of oocytes expressing short Osk alone. 45 Osk induces the formation of long actin projections from the posterior cortex into the pole plasm, corroborating the link between osk anchoring and the F-actin cytoskeleton.…”