Glorund, a Drosophila hnRNP F/H Homolog, Is an Ovarian Repressor of nanos Translation

Abstract

Patterning of the anterior-posterior body axis of the Drosophila embryo requires production of Nanos protein selectively in the posterior. Spatially restricted Nanos synthesis is accomplished by translational repression of unlocalized nanos mRNA together with translational activation of posteriorly localized nanos. Repression of unlocalized nanos mRNA is mediated by a bipartite translational control element (TCE) in its 3' untranslated region. TCE stem-loop II functions during embryogenesis, through its interaction with the Smaug repressor. Stem-loop III represses unlocalized nanos mRNA during oogenesis, but trans-acting factors that carry out this function have remained elusive. Here we identify a Drosophila hnRNP, Glorund, that interacts specifically with stem-loop III. We establish that the ability of the TCE to repress translation in vivo reflects its ability to bind Glorund in vitro. These data, together with the analysis of a glorund null mutant, reveal a specific role for an hnRNP in repression of nanos translation during oogenesis.

Heterogeneous Nuclear Ribonucleoprotein (hnRNP) F Is a Novel Component of Oligodendroglial RNA Transport Granules Contributing to Regulation of Myelin Basic Protein (MBP) Synthesis

“…hnRNP F Is a Novel Functional Component of Oligodendrocyte MBP mRNA Granules-Intriguingly, Glorund has been shown to regulate the translation of nanos mRNA during Drosophila oogenesis (31). The cytoplasmic distribution in nurse cells and oocytes resembles the hnRNP F-containing RNA granules we observed in oligodendrocytes.…”

“…1A). The homologue of hnRNP F in Drosophila, Glorund, has been shown to regulate the translation of specific mRNAs in the cytoplasm of oocytes (31). As the granular pattern of hnRNP F staining resembled the cytoplasmic distribution of hnRNP A2 and E1, proteins that play a role in the localization and translation of MBP mRNA in oligodendrocytes (21, 32), we further evaluated a potential cytoplasmic function of hnRNP F. A substantial fraction of hnRNP F colocalizes with hnRNP A2 in cytoplasmic granular structures of differentiated Oli-neu cells and primary oligodendrocytes (Fig.…”

Emerging Roles for hnRNPs in post-transcriptional regulation: what can we learn from flies?

“…3c). Interestingly, the Drosophila hnRNP Glorund (Glo), together with Smg, contributes to the specific translational repression of nos mRNA (Kalifa et al 2006). Glo protein is part of a complex that also contains the hnRNP Hrb27C, the splicing factor Half-pint and the Otu protein (Fig.…”

“…Grk, osk and nos and mRNAs are in orange, green and violet lines, respectively. stages to regulate the translation of neuronal mRNAs (Piper and Holt 2004;Martin 2005;Kalifa et al 2006;Olson et al 2007). Moreover, the hnRNP Hrb87F, in addition to its role in omega speckle formation as well as normal development and stress tolerance , is also widely involved in neuronal development.…”

“…Cell polarity HNRNPH2, GRSF1, HNRNPH3, RBM12, HNRNPH1, HNRNPF [Kalifa et al 2006] heph hephaestus PTB, CG2094, l(3)03429, dmPTB, ema…”