title: oskar RNA plays multiple noncoding roles to support oogenesis and maintain integrity of the germline/soma distinction.
abstract: The Drosophila oskar (osk) mRNA is unusual in that it has both coding and noncoding functions. As an mRNA, osk encodes a protein required for embryonic patterning and germ cell formation. Independent of that function, the absence of osk mRNA disrupts formation of the karyosome and blocks progression through oogenesis. Here we show that loss of osk mRNA also affects the distribution of regulatory proteins, relaxing their association with large RNPs within the germline, and allowing them to accumulate in the somatic follicle cells. This and other noncoding functions of the osk mRNA are mediated by multiple sequence elements with distinct roles. One role, provided by numerous binding sites in two distinct regions of the osk 3' UTR, is to sequester the translational regulator Bruno (Bru), which itself controls translation of osk mRNA. This defines a novel regulatory circuit, with Bru restricting the activity of osk, and osk in turn restricting the activity of Bru. Other functional elements, which do not bind Bru and are positioned close to the 3' end of the RNA, act in the oocyte and are essential. Despite the different roles played by the different types of elements contributing to RNA function, mutation of any leads to accumulation of the germline regulatory factors in the follicle cells.
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Matt
authors: M
authors: Kanke
authors: Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
authors: Helena
authors: H
authors: Jambor
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: John
authors: J
authors: Reich
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Brittany
authors: B
authors: Marches
authors: Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
authors: Ronald
authors: R
authors: Gstir
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Young Hee
authors: YH
authors: Ryu
authors: Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
authors: Anne
authors: A
authors: Ephrussi
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Paul M
authors: PM
authors: Macdonald
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001665:Binding Sites; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D009154:Mutation; D009866:Oogenesis; D010063:Ovum / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D050436:Regulatory Elements, Transcriptional
chemical_list: D020413:3' Untranslated Regions; D029721:Drosophila Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C093437:bru1 protein, Drosophila; C091675:osk protein, Drosophila
keywords: Bruno; lncRNA function; oskar; protein sequestration