title: Human mitochondrial RNA decay mediated by PNPase-hSuv3 complex takes place in distinct foci.
abstract: RNA decay is usually mediated by protein complexes and can occur in specific foci such as P-bodies in the cytoplasm of eukaryotes. In human mitochondria nothing is known about the spatial organization of the RNA decay machinery, and the ribonuclease responsible for RNA degradation has not been identified. We demonstrate that silencing of human polynucleotide phosphorylase (PNPase) causes accumulation of RNA decay intermediates and increases the half-life of mitochondrial transcripts. A combination of fluorescence lifetime imaging microscopy with Förster resonance energy transfer and bimolecular fluorescence complementation (BiFC) experiments prove that PNPase and hSuv3 helicase (Suv3, hSuv3p and SUPV3L1) form the RNA-degrading complex in vivo in human mitochondria. This complex, referred to as the degradosome, is formed only in specific foci (named D-foci), which co-localize with mitochondrial RNA and nucleoids. Notably, interaction between PNPase and hSuv3 is essential for efficient mitochondrial RNA degradation. This provides indirect evidence that degradosome-dependent mitochondrial RNA decay takes place in foci.
authors.affiliation: Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland.
authors.forename: Lukasz S
authors.initials: LS
authors.lastname: Borowski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Dziembowski
authors.forename: Monika S
authors.initials: MS
authors.lastname: Hejnowicz
authors.forename: Piotr P
authors.initials: PP
authors.lastname: Stepien
authors.forename: Roman J
authors.initials: RJ
authors.lastname: Szczesny
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D048708:Cell Growth Processes; D002460:Cell Line; D053487:DEAD-box RNA Helicases / Q000032:analysis / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000032:analysis; D004722:Endoribonucleases / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism*; D011117:Polyribonucleotide Nucleotidyltransferase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000032:analysis / Q000378:metabolism*; D020365:RNA Helicases / Q000378:metabolism*; D020871:RNA Stability; D000077278:RNA, Mitochondrial
chemical_list: D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; D000077278:RNA, Mitochondrial; C111244:degradosome; D012313:RNA; D000255:Adenosine Triphosphate; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases; C469673:SUPV3L1 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases