OPA1 links human mitochondrial genome maintenance to mtDNA replication and distribution
- Ghizlane Elachouri1,10,
- Sara Vidoni1,2,10,
- Claudia Zanna2,
- Alexandre Pattyn1,
- Hassan Boukhaddaoui1,
- Karen Gaget1,
- Patrick Yu-Wai-Man3,
- Giuseppe Gasparre4,
- Emmanuelle Sarzi5,
- Cécile Delettre1,
- Aurélien Olichon6,
- Dominique Loiseau7,
- Pascal Reynier7,
- Patrick F. Chinnery3,
- Agnès Rotig5,
- Valerio Carelli8,
- Christian P. Hamel1,9,
- Michela Rugolo2 and
- Guy Lenaers1,11
- 1 INSERM U-583, Institut des Neurosciences de Montpellier, Montpellier, France and Université de Montpellier I et II, Montpellier 34091, France;
- 2 Dipartimento di Biologia Evoluzionistica Sperimentale, Università di Bologna, Bologna 40126, Italy;
- 3 Mitochondrial Research Group, Institute of Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE1 3BZ, United Kingdom;
- 4 Dipartimento di Biochimica e Biologia Molecolare, E. Quagliariello, Università di Bari, Bari 70126, Italy;
- 5 INSERM U-781, Hôpital Necker-Enfants Malades, Paris 75015, France;
- 6 INSERM U-563, Institut Claudius Regaud, Toulouse 31052, France;
- 7 INSERM U771, CHU d'Angers, Angers 49933, France;
- 8 Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna 40123, Italy;
- 9 CHRU Montpellier, Centre of Reference for Genetic Sensory Diseases, Montpellier 34295, France
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↵10 These authors contributed equally to this work.
Abstract
Eukaryotic cells harbor a small multiploid mitochondrial genome, organized in nucleoids spread within the mitochondrial network. Maintenance and distribution of mitochondrial DNA (mtDNA) are essential for energy metabolism, mitochondrial lineage in primordial germ cells, and to prevent mtDNA instability, which leads to many debilitating human diseases. Mounting evidence suggests that the actors of the mitochondrial network dynamics, among which is the intramitochondrial dynamin OPA1, might be involved in these processes. Here, using siRNAs specific to OPA1 alternate spliced exons, we evidenced that silencing of the OPA1 variants including exon 4b leads to mtDNA depletion, secondary to inhibition of mtDNA replication, and to marked alteration of mtDNA distribution in nucleoid and nucleoid distribution throughout the mitochondrial network. We demonstrate that a small hydrophobic 10-kDa peptide generated by cleavage of the OPA1-exon4b isoform is responsible for this process and show that this peptide is embedded in the inner membrane and colocalizes and coimmunoprecipitates with nucleoid components. We propose a novel synthetic model in which a peptide, including two trans-membrane domains derived from the N terminus of the OPA1-exon4b isoform in vertebrates or from its ortholog in lower eukaryotes, might contribute to nucleoid attachment to the inner mitochondrial membrane and promotes mtDNA replication and distribution. Thus, this study places OPA1 as a direct actor in the maintenance of mitochondrial genome integrity.
Footnotes
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↵11 Corresponding author.
E-mail guy.lenaers{at}inserm.fr; fax (33) 499-63-60-20.
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[Supplemental material is available online at http://www.genome.org.]
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Article published online before print. Article and publication date are at http://www.genome.org/cgi/doi/10.1101/gr.108696.110.
- Received April 3, 2010.
- Accepted October 12, 2010.
- Copyright © 2011 by Cold Spring Harbor Laboratory Press