title: Organellar non-coding RNAs: emerging regulation mechanisms.
abstract: Originally focused on the nuclear and cytosolic compartments, the concept of regulation driven by non-coding RNAs (ncRNAs) is extending to mitochondria and chloroplasts. These organelles have distinct genetic systems that need coordination with cellular demands. In mammals, nuclear-encoded microRNAs were found associated with the mitochondria. Some of these contribute to the regulation of mitochondrial transcription and translation. Others were proposed to be stored in the organelles and to be released for regulation of nuclear transcripts. Further ncRNAs of various sizes derive from the mitochondrial genome and it was speculated that organelles host antisense or RNA interference pathways. Long ncRNAs mapping to the mitochondrial DNA seem to operate in the nucleus. Altogether, the origin and trafficking of ncRNAs categorized as mitochondrial in mammals raise questions far beyond the current knowledge. In protozoa, hundreds of guide RNAs specify editing events needed to generate functional messenger RNAs. Only few ncRNAs have been reported in plant mitochondria, but editing sites were revealed in non-coding regions of the organellar genome, suggesting that the corresponding transcripts have a function. Conversely, numerous ncRNA candidates were identified in chloroplasts, essentially mapping to the plastid genome. A synthetic view of the data with their functional implications is given here.
authors.affiliation: Institut de biologie moléculaire des plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France. Electronic address: andre.dietrich@ibmp-cnrs.unistra.fr.
authors.forename: André
authors.initials: A
authors.lastname: Dietrich
authors.affiliation: Institut de biologie moléculaire des plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France. Electronic address: clementine.wallet@ibmp-cnrs.unistra.fr.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Wallet
authors.affiliation: Institut de biologie moléculaire des plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France. Electronic address: khalid.iqbal@ibmp-cnrs.unistra.fr.
authors.forename: Rana Khalid
authors.initials: RK
authors.lastname: Iqbal
authors.affiliation: Institut de biologie moléculaire des plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France. Electronic address: jose.gualberto@ibmp-cnrs.unistra.fr.
authors.forename: José M
authors.initials: JM
authors.lastname: Gualberto
authors.affiliation: Institut de biologie moléculaire des plantes, CNRS and Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France. Electronic address: lotfif@unistra.fr.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Lotfi
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008928:Mitochondria / Q000235:genetics*; D008957:Models, Genetic; D010944:Plants / Q000235:genetics*; D022661:RNA, Untranslated / Q000235:genetics* / Q000378:metabolism
chemical_list: D022661:RNA, Untranslated
keywords: Antisense regulation; Chloroplasts; Mitochondria; Non-coding RNA; RNA interference; RNA trafficking