Inscuteable and Staufen Mediate Asymmetric Localization and Segregation of prospero RNA during Drosophila Neuroblast Cell Divisions

Abstract

When neuroblasts divide, inscuteable acts to coordinate protein localization and mitotic spindle orientation, ensuring that asymmetrically localized determinants like Prospero partition into one progeny. staufen encodes a dsRNA-binding protein implicated in mRNA transport in oocytes. We demonstrate that prospero RNA is also asymmetrically localized and partitioned during neuroblast cell divisions, a process requiring both inscuteable and staufen. Inscuteable and Staufen interact and colocalize with prospero RNA on the apical cortex of interphase neuroblasts. Staufen binds prospero RNA in its 3'UTR. Our findings suggest that Inscuteable nucleates an apical complex and is required for protein localization, spindle orientation, and RNA localization. Stau, as one component of this complex, is required only for RNA localization. Hence staufen also acts zygotically, downstream of inscuteable, to effect aspects of neuroblast asymmetry.

Cloning and characterization of the mouse Interleukin Enhancer Binding Factor 3 ( Ilf3 ) homolog in a screen for RNA binding proteins

“…To date, no dsRBM-containing protein has shown sequence-specific binding in vitro. However, in vivo experiments with the Drosophila protein Staufen, which contains five copies of the dsRBM, indicates it can interact with selected RNAs (Broadus et al 1998;Ferrandon et al 1994;KimHa et al 1991;Li et al 1997). Most proteins with the dsRNA binding motif have more than one copy, although some copies are non-functional or not required for RNA binding (Bycroft et al 1995;St Johnston et al 1992).…”

RNA Targets and Specificity of Staufen, a Double-stranded RNA-binding Protein in Caenorhabditis elegans

“…These defects are caused, at least in part, by mislocalization of mRNAs, such as oskar and bicoid, in the developing oocyte and embryo (32,33). Staufen is also required for efficient localization of prospero mRNA during the formation of neuroblasts (10,34). Staufen associates with the bicoid and prospero 3Ј-untranslated regions (UTR) in vivo.…”

Polarité cellulaire et localisation intracellulaire des ARNm de l’actine

“…Cependant, dans de nombreux cas, l'ARN est capable d'assembler une structure spécifiquement destinée à son transport. Ces structures, appelées granules ou, plus récemment, locasomes, ont été mises en évidence dans de nombreux systèmes : la levure [16], les embryons et cellules somatiques de drosophile [17], ou encore les cellules somatiques de vertébrés, principalement les neurones [18,19]. L'assemblage d'une structure dévolue au transport de l'ARN procure plusieurs avantages.…”