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Franchino CA, Brughera M, Baderna V, De Ritis D, Rocco A, Seneca S, Regal L, Podini P, D’Antonio M, Toro C, Quattrini A, Scalais E, Maltecca F. Sustained OMA1-mediated integrated stress response is beneficial for spastic ataxia type 5. Brain 2024; 147:1043-1056. [PMID: 37804316 PMCID: PMC10907083 DOI: 10.1093/brain/awad340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/28/2023] [Accepted: 09/12/2023] [Indexed: 10/09/2023] Open
Abstract
AFG3L2 is a mitochondrial protease exerting protein quality control in the inner mitochondrial membrane. Heterozygous AFG3L2 mutations cause spinocerebellar ataxia type 28 (SCA28) or dominant optic atrophy type 12 (DOA12), while biallelic AFG3L2 mutations result in the rare and severe spastic ataxia type 5 (SPAX5). The clinical spectrum of SPAX5 includes childhood-onset cerebellar ataxia, spasticity, dystonia and myoclonic epilepsy. We previously reported that the absence or mutation of AFG3L2 leads to the accumulation of mitochondria-encoded proteins, causing the overactivation of the stress-sensitive protease OMA1, which over-processes OPA1, leading to mitochondrial fragmentation. Recently, OMA1 has been identified as the pivotal player communicating mitochondrial stress to the cytosol via a pathway involving the inner mitochondrial membrane protein DELE1 and the cytosolic kinase HRI, thus eliciting the integrated stress response. In general, the integrated stress response reduces global protein synthesis and drives the expression of cytoprotective genes that allow cells to endure proteotoxic stress. However, the relevance of the OMA1-DELE1-HRI axis in vivo, and especially in a human CNS disease context, has been poorly documented thus far. In this work, we demonstrated that mitochondrial proteotoxicity in the absence/mutation of AFG3L2 activates the OMA1-DELE1-HRI pathway eliciting the integrated stress response. We found enhanced OMA1-dependent processing of DELE1 upon depletion of AFG3L2. Also, in both skin fibroblasts from SPAX5 patients (including a novel case) and in the cerebellum of Afg3l2-/- mice we detected increased phosphorylation of the α-subunit of the eukaryotic translation initiation factor 2 (eIF2α), increased levels of ATF4 and strong upregulation of its downstream targets (Chop, Chac1, Ppp1r15a and Ffg21). Silencing of DELE1 or HRI in SPAX5 fibroblasts (where OMA1 is overactivated at basal state) reduces eIF2α phosphorylation and affects cell growth. In agreement, pharmacological potentiation of integrated stress response via Sephin-1, a drug that selectively inhibits the stress-induced eIF2alpha phosphatase GADD34 (encoded by Ppp1r15a), improved cell growth of SPAX5 fibroblasts and cell survival and dendritic arborization ex vivo in primary Afg3l2-/- Purkinje neurons. Notably, Sephin-1 treatment in vivo extended the lifespan of Afg3l2-/- mice, improved Purkinje neuron morphology, mitochondrial ultrastructure and respiratory capacity. These data indicate that activation of the OMA1-DELE1-HRI pathway is protective in the context of SPAX5. Pharmacological tuning of the integrated stress response may represent a future therapeutic strategy for SPAX5 and other cerebellar ataxias caused by impaired mitochondrial proteostasis.
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Affiliation(s)
- Camilla Aurora Franchino
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Martina Brughera
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Valentina Baderna
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Daniele De Ritis
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Alessandra Rocco
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Sara Seneca
- Medical Center of Genetic, UZ-VUB, Vrije Universiteit Brussels, 1090 Brussels Jette, Belgium
| | - Luc Regal
- Pediatric Neurology and Metabolism, UZ-VUB, Vrije Universiteit Brussels, 1090 Brussels Jette, Belgium
| | - Paola Podini
- Experimental Neuropathology Unit, Division of Neuroscience and Institute of Experimental Neurology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Maurizio D’Antonio
- Biology of Myelin Unit, Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Camilo Toro
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Angelo Quattrini
- Experimental Neuropathology Unit, Division of Neuroscience and Institute of Experimental Neurology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Emmanuel Scalais
- Department of Pediatric, Division of Pediatric Neurology, Centre Hospitalier de Luxembourg, L1210 Luxembourg, Luxembourg
| | - Francesca Maltecca
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
- Università Vita-Salute San Raffaele, 20132 Milan, Italy
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Zaghi M, Longo F, Massimino L, Rubio A, Bido S, Mazzara PG, Bellini E, Banfi F, Podini P, Maltecca F, Zippo A, Broccoli V, Sessa A. SETD5 haploinsufficiency affects mitochondrial compartment in neural cells. Mol Autism 2023; 14:20. [PMID: 37264456 DOI: 10.1186/s13229-023-00550-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/18/2023] [Indexed: 06/03/2023] Open
Abstract
BACKGROUND Neurodevelopmental disorders (NDDs) are heterogeneous conditions due to alterations of a variety of molecular mechanisms and cell dysfunctions. SETD5 haploinsufficiency leads to NDDs due to chromatin defects. Epigenetic basis of NDDs has been reported in an increasing number of cases while mitochondrial dysfunctions are more common within NDD patients than in the general population. METHODS We investigated in vitro neural stem cells as well as the brain of the Setd5 haploinsufficiency mouse model interrogating its transcriptome, analyzing mitochondrial structure, biochemical composition, and dynamics, as well as mitochondrial functionality. RESULTS Mitochondrial impairment is facilitated by transcriptional aberrations originated by the decrease of the SETD5 enzyme. Low levels of SETD5 resulted in fragmented mitochondria, reduced mitochondrial membrane potential, and ATP production both in neural precursors and neurons. Mitochondria were also mislocalized in mutant neurons, with reduced organelles within neurites and synapses. LIMITATIONS We found several defects in the mitochondrial compartment; however, we can only speculate about their position in the hierarchy of the pathological mechanisms at the basis of the disease. CONCLUSIONS Our study explores the interplay between chromatin regulation and mitochondria functions as a possible important aspect of SETD5-associated NDD pathophysiology. Our data, if confirmed in patient context, suggest that the mitochondrial activity and dynamics may represent new therapeutic targets for disorders associated with the loss of SETD5.
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Affiliation(s)
- Mattia Zaghi
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
| | - Fabiana Longo
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
- University California, Irvine, USA
| | - Luca Massimino
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
| | - Alicia Rubio
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
- CNR Institute of Neuroscience, 20129, Milan, Italy
| | - Simone Bido
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
| | - Pietro Giuseppe Mazzara
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
- Department of Genetics and Development, Columbia University, New York, NY, 10032, USA
| | - Edoardo Bellini
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
| | - Federica Banfi
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy
- CNR Institute of Neuroscience, 20129, Milan, Italy
| | - Paola Podini
- Experimental Neuropathology Unit, INSPE, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Francesca Maltecca
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Alessio Zippo
- Chromatin Biology and Epigenetics Lab, Department of Cellular, Computational, and Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy
| | - Vania Broccoli
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy.
- CNR Institute of Neuroscience, 20129, Milan, Italy.
| | - Alessandro Sessa
- Stem Cell and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy.
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Del Bondio A, Longo F, De Ritis D, Spirito E, Podini P, Brais B, Bachi A, Quattrini A, Maltecca F. Restoring calcium homeostasis in Purkinje cells arrests neurodegeneration and neuroinflammation in the ARSACS mouse model. JCI Insight 2023:163576. [PMID: 37159335 PMCID: PMC10371240 DOI: 10.1172/jci.insight.163576] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) is caused by mutations in SACS gene encoding sacsin, a huge protein highly expressed in cerebellar Purkinje cells (PCs). ARSACS patients, as well as mouse models, display early degeneration of PCs, but the underlying mechanisms remain unexplored, with no available treatments.In this work, we demonstrated aberrant calcium (Ca2+) homeostasis and its impact on PC degeneration in ARSACS. Mechanistically, we found pathological elevation in Ca2+-evoked responses in Sacs-/- PCs, as the result of defective mitochondria and ER trafficking to distal dendrites and strong downregulation of key Ca2+ buffer-proteins. Alteration of cytoskeletal linkers, that we identified as specific sacsin interactors, likely account for faulty organellar trafficking in Sacs-/- cerebellum.Based on this pathogenetic cascade, we treated Sacs-/- mice with Ceftriaxone, a repurposed drug which exerts neuroprotection by limiting neuronal glutamatergic stimulation, and thus Ca2+ fluxes into PCs. Ceftriaxone treatment significantly improved motor performances of Sacs-/- mice, at both pre- and post-symptomatic stages. We correlated this effect to restored Ca2+ homeostasis, which arrests PC degeneration and attenuates secondary neuroinflammation. These findings disclose new key steps in ARSACS pathogenesis and support further optimization of Ceftriaxone in pre-clinical and clinical settings for the treatment of ARSACSpatients.
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Affiliation(s)
- Andrea Del Bondio
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Fabiana Longo
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Daniele De Ritis
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Erica Spirito
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Paola Podini
- Division of Neuroscience and Institute of Experimental Neurology, Ospedale San Raffaele, Milan, Italy
| | - Bernard Brais
- Department of Neurology and Neurosurgery, McGill University, Montréal, Canada
| | - Angela Bachi
- Functional Proteomics Unit, IFOM- FIRC Institute of Molecular Oncology, Milan, Italy
| | - Angelo Quattrini
- Division of Neuroscience and Institute of Experimental Neurology, Ospedale San Raffaele, Milan, Italy
| | - Francesca Maltecca
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
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Longo F, De Ritis D, Miluzio A, Fraticelli D, Baets J, Scarlato M, Santorelli FM, Biffo S, Maltecca F. Assessment of Sacsin Turnover in Patients With ARSACS: Implications for Molecular Diagnosis and Pathogenesis. Neurology 2021; 97:e2315-e2327. [PMID: 34649874 PMCID: PMC8665432 DOI: 10.1212/wnl.0000000000012962] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 10/07/2021] [Indexed: 11/15/2022] Open
Abstract
Background and Objectives Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is caused by variations in SACS gene encoding sacsin, a huge multimodular protein of unknown function. More than 200 SACS variations have been described worldwide to date. Because ARSACS presents phenotypic variability, previous empirical studies attempted to correlate the nature and position of SACS variations with the age at onset or with disease severity, although not considering the effect of the various variations on protein stability. In this work, we studied genotype-phenotype correlation in ARSACS at a functional level. Methods We analyzed a large set of skin fibroblasts derived from patients with ARSACS, including both new and already published cases, carrying variations of different types affecting diverse domains of the protein. Results We found that sacsin is almost absent in patients with ARSACS, regardless of the nature of the variation. As expected, we did not detect sacsin in patients with truncating variations. We found it strikingly reduced or absent also in compound heterozygotes carrying diverse missense variations. In this case, we excluded SACS mRNA decay, defective translation, or faster posttranslational degradation as possible causes of protein reduction. Conversely, our results demonstrate that nascent mutant sacsin protein undergoes cotranslational ubiquitination and degradation. Discussion Our results provide a mechanistic explanation for the lack of genotype-phenotype correlation in ARSACS. We also propose a new and unambiguous criterion for ARSACS diagnosis that is based on the evaluation of sacsin level. Last, we identified preemptive degradation of a mutant protein as a novel cause of a human disease.
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Affiliation(s)
- Fabiana Longo
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Daniele De Ritis
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Annarita Miluzio
- Istituto Nazionale di Genetica Molecolare, INGM, "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Davide Fraticelli
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy
| | - Jonathan Baets
- Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerpen, Belgium
| | - Marina Scarlato
- Department of Neurology, Ospedale San Raffaele, Milan, Italy
| | | | - Stefano Biffo
- Istituto Nazionale di Genetica Molecolare, INGM, "Romeo ed Enrica Invernizzi", Milan, Italy.,Department of Biosciences, University of Milan, Milan, Italy
| | - Francesca Maltecca
- Mitochondrial Dysfunctions in Neurodegeneration Unit, Ospedale San Raffaele, Milan, Italy .,Università Vita-Salute San Raffaele, Milan, Italy
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Sferruzza G, Del Bondio A, Citterio A, Vezzulli P, Guerrieri S, Radaelli M, Martinelli Boneschi F, Filippi M, Maltecca F, Bassi MT, Scarlato M. U-Fiber Leukoencephalopathy Due to a Novel Mutation in the TACO1 Gene. Neurol Genet 2021; 7:e573. [PMID: 33709035 PMCID: PMC7943219 DOI: 10.1212/nxg.0000000000000573] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/12/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Giacomo Sferruzza
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Andrea Del Bondio
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Andrea Citterio
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Paolo Vezzulli
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Simone Guerrieri
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Marta Radaelli
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Filippo Martinelli Boneschi
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Massimo Filippi
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Francesca Maltecca
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Maria Teresa Bassi
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
| | - Marina Scarlato
- Department of Neurology (G.S., S.G., M.F., M.S.), and Mitochondrial Dysfunctions in Neurodegeneration Unit (A.D.B., F.M.), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan; Laboratory of Molecular Biology (A.C., M.T.B.), Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco; Department of Neuroradiology (P.V.), IRCCS San Raffaele Scientific Institute, Milan; Department of Neurology (M.R.), Papa Giovanni XXIII, Bergamo; Dino Ferrari Centre (F.M.B.), Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan; and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.B.), Neurology Unit and Multiple Sclerosis Center, Milan, Italy
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Longo F, Benedetti S, Zambon AA, Sora MGN, Di Resta C, De Ritis D, Quattrini A, Maltecca F, Ferrari M, Previtali SC. Impaired turnover of hyperfused mitochondria in severe axonal neuropathy due to a novel DRP1 mutation. Hum Mol Genet 2020; 29:177-188. [PMID: 31868880 DOI: 10.1093/hmg/ddz211] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 08/09/2019] [Accepted: 08/28/2019] [Indexed: 12/09/2022] Open
Abstract
Mitochondria undergo continuous cycles of fusion and fission in response to physiopathological stimuli. The key player in mitochondrial fission is dynamin-related protein 1 (DRP1), a cytosolic protein encoded by dynamin 1-like (DNM1L) gene, which relocalizes to the outer mitochondrial membrane, where it assembles, oligomerizes and drives mitochondrial division upon guanosine-5'-triphosphate (GTP) hydrolysis. Few DRP1 mutations have been described so far, with patients showing complex and variable phenotype ranging from early death to encephalopathy and/or optic atrophy. The disease is the consequence of defective mitochondrial fission due to faulty DRP1 function. However, the underlying molecular mechanisms and the functional consequences at mitochondrial and cellular level remain elusive. Here we report on a 5-year-old girl presenting psychomotor developmental delay, global hypotonia and severe ataxia due to axonal sensory neuropathy harboring a novel de novo heterozygous missense mutation in the GTPase domain of DRP1 (NM_012062.3:c.436G>A, NP_036192.2: p.D146N variant in DNM1L). Patient's fibroblasts show hyperfused/balloon-like giant mitochondria, highlighting the importance of D146 residue for DRP1 function. This dramatic mitochondrial rearrangement phenocopies what observed overexpressing DRP1-K38A, a well-known experimental dominant negative version of DRP1. In addition, we demonstrated that p.D146N mutation has great impact on peroxisomal shape and function. The p.D146N mutation compromises the GTPase activity without perturbing DRP1 recruitment or assembly, causing decreased mitochondrial and peroxisomal turnover. In conclusion, our findings highlight the importance of sensory neuropathy in the clinical spectrum of DRP1 variants and, for the first time, the impact of DRP1 mutations on mitochondrial turnover and peroxisomal functionality.
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Affiliation(s)
- Fabiana Longo
- Neurogenomics Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Sara Benedetti
- Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Alberto A Zambon
- Department of Neurology, IRCCS Ospedale San Raffaele, Milan, Italy
| | | | - Chiara Di Resta
- Università Vita-Salute San Raffaele, Milan, Italy.,Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology IRCCS Ospedale San Raffaele, Milan, Italy
| | - Daniele De Ritis
- Neurogenomics Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Angelo Quattrini
- Department of Neurology, IRCCS Ospedale San Raffaele, Milan, Italy.,Inspe and Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Francesca Maltecca
- Neurogenomics Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
| | - Maurizio Ferrari
- Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy.,Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology IRCCS Ospedale San Raffaele, Milan, Italy
| | - Stefano Carlo Previtali
- Department of Neurology, IRCCS Ospedale San Raffaele, Milan, Italy.,Inspe and Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
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7
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Baderna V, Schultz J, Kearns LS, Fahey M, Thompson BA, Ruddle JB, Huq A, Maltecca F. A novel AFG3L2 mutation close to AAA domain leads to aberrant OMA1 and OPA1 processing in a family with optic atrophy. Acta Neuropathol Commun 2020; 8:93. [PMID: 32600459 PMCID: PMC7325028 DOI: 10.1186/s40478-020-00975-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 06/19/2020] [Indexed: 12/14/2022] Open
Abstract
Autosomal dominant optic atrophy (ADOA) is a neuro-ophthalmic condition characterized by bilateral degeneration of the optic nerves. Although heterozygous mutations in OPA1 represent the most common genetic cause of ADOA, a significant number of cases remain undiagnosed. Here, we describe a family with a strong ADOA history with most family members spanning three generation having childhood onset of visual symptoms. The proband, in addition to optic atrophy, had neurological symptoms consistent with relapsing remitting multiple sclerosis. Clinical exome analysis detected a novel mutation in the AFG3L2 gene (NM_006796.2:c.1010G > A; p.G337E), which segregated with optic atrophy in family members. AFG3L2 is a metalloprotease of the AAA subfamily which exerts quality control in the inner mitochondrial membrane. Interestingly, the identified mutation localizes close to the AAA domain of AFG3L2, while those localized in the proteolytic domain cause dominant spinocerebellar ataxia type 28 (SCA28) or recessive spastic ataxia with epilepsy (SPAX5). Functional studies in patient fibroblasts demonstrate that the p.G337E AFG3L2 mutation strongly destabilizes the long isoforms of OPA1 via OMA hyper-activation and leads to mitochondrial fragmentation, thus explaining the family phenotype. This study widens the clinical spectrum of neurodegenerative diseases caused by AFG3L2 mutations, which shall be considered as genetic cause of ADOA.
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8
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Carvalho HJF, Del Bondio A, Maltecca F, Colombo SF, Borgese N. The WRB Subunit of the Get3 Receptor is Required for the Correct Integration of its Partner CAML into the ER. Sci Rep 2019; 9:11887. [PMID: 31417168 PMCID: PMC6695381 DOI: 10.1038/s41598-019-48363-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/02/2019] [Indexed: 11/24/2022] Open
Abstract
Calcium-modulating cyclophilin ligand (CAML), together with Tryptophan rich basic protein (WRB, Get1 in yeast), constitutes the mammalian receptor for the Transmembrane Recognition Complex subunit of 40 kDa (TRC40, Get3 in yeast), a cytosolic ATPase with a central role in the post-translational targeting pathway of tail-anchored (TA) proteins to the endoplasmic reticulum (ER) membrane. CAML has also been implicated in other cell-specific processes, notably in immune cell survival, and has been found in molar excess over WRB in different cell types. Notwithstanding the stoichiometric imbalance, WRB and CAML depend strictly on each other for expression. Here, we investigated the mechanism by which WRB impacts CAML levels. We demonstrate that CAML, generated in the presence of sufficient WRB levels, is inserted into the ER membrane with three transmembrane segments (TMs) in its C-terminal region. By contrast, without sufficient levels of WRB, CAML fails to adopt this topology, and is instead incompletely integrated to generate two aberrant topoforms; these congregate in ER-associated clusters and are degraded by the proteasome. Our results suggest that WRB, a member of the recently proposed Oxa1 superfamily, acts catalytically to assist the topogenesis of CAML and may have wider functions in membrane biogenesis than previously appreciated.
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Affiliation(s)
- Hugo J F Carvalho
- Consiglio Nazionale delle Ricerche Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano, I-20129, Milan, Italy.,Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Andrea Del Bondio
- Division of Neuroscience, Ospedale San Raffaele, I-20132, Milan, Italy
| | | | - Sara F Colombo
- Consiglio Nazionale delle Ricerche Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano, I-20129, Milan, Italy.
| | - Nica Borgese
- Consiglio Nazionale delle Ricerche Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano, I-20129, Milan, Italy.
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9
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Tulli S, Del Bondio A, Baderna V, Mazza D, Codazzi F, Pierson TM, Ambrosi A, Nolte D, Goizet C, Toro C, Baets J, Deconinck T, DeJonghe P, Mandich P, Casari G, Maltecca F. Pathogenic variants in the AFG3L2 proteolytic domain cause SCA28 through haploinsufficiency and proteostatic stress-driven OMA1 activation. J Med Genet 2019; 56:499-511. [PMID: 30910913 PMCID: PMC6678042 DOI: 10.1136/jmedgenet-2018-105766] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/05/2019] [Accepted: 03/03/2019] [Indexed: 12/18/2022]
Abstract
Background Spinocerebellar ataxia type 28 (SCA28) is a dominantly inherited neurodegenerative disease caused by pathogenic variants in AFG3L2. The AFG3L2 protein is a subunit of mitochondrial m-AAA complexes involved in protein quality control. Objective of this study was to determine the molecular mechanisms of SCA28, which has eluded characterisation to date. Methods We derived SCA28 patient fibroblasts carrying different pathogenic variants in the AFG3L2 proteolytic domain (missense: the newly identified p.F664S and p.M666T, p.G671R, p.Y689H and a truncating frameshift p.L556fs) and analysed multiple aspects of mitochondrial physiology. As reference of residual m-AAA activity, we included SPAX5 patient fibroblasts with homozygous p.Y616C pathogenic variant, AFG3L2+/− HEK293 T cells by CRISPR/Cas9-genome editing and Afg3l2−/− murine fibroblasts. Results We found that SCA28 cells carrying missense changes have normal levels of assembled m-AAA complexes, while the cells with a truncating pathogenic variant had only half of this amount. We disclosed inefficient mitochondrial fusion in SCA28 cells caused by increased OPA1 processing operated by hyperactivated OMA1. Notably, we found altered mitochondrial proteostasis to be the trigger of OMA1 activation in SCA28 cells, with pharmacological attenuation of mitochondrial protein synthesis resulting in stabilised levels of OMA1 and OPA1 long forms, which rescued mitochondrial fusion efficiency. Secondary to altered mitochondrial morphology, mitochondrial calcium uptake resulted decreased in SCA28 cells. Conclusion Our data identify the earliest events in SCA28 pathogenesis and open new perspectives for therapy. By identifying similar mitochondrial phenotypes between SCA28 cells and AFG3L2+/− cells, our results support haploinsufficiency as the mechanism for the studied pathogenic variants.
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Affiliation(s)
- Susanna Tulli
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Andrea Del Bondio
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Valentina Baderna
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Davide Mazza
- Experimental Imaging Center, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Franca Codazzi
- Università Vita-Salute San Raffaele, Milan, Italy.,Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Tyler Mark Pierson
- Departments of Pediatrics and Neurology and the Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | | | - Dagmar Nolte
- Department of Medicine, Institute for Human Genetics, Justus-Liebig-University Giessen, Giessen, Germany
| | - Cyril Goizet
- Centre de Reference Neurogenetique, Service de Genetique Medicale, CHU Bordeaux, Bordeaux, France.,Laboratoire MRGM, INSERM U1211, Bordeaux, France
| | - Camilo Toro
- Undiagnosed Disease Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, Maryland, USA
| | - Jonathan Baets
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Tine Deconinck
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Peter DeJonghe
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Paola Mandich
- DINOGMI, University of Genoa and IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Giorgio Casari
- Università Vita-Salute San Raffaele, Milan, Italy.,Telethon Institute of Genetics and Medicine, Naples, Italy
| | - Francesca Maltecca
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
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10
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Mancini C, Hoxha E, Iommarini L, Brussino A, Richter U, Montarolo F, Cagnoli C, Parolisi R, Gondor Morosini DI, Nicolò V, Maltecca F, Muratori L, Ronchi G, Geuna S, Arnaboldi F, Donetti E, Giorgio E, Cavalieri S, Di Gregorio E, Pozzi E, Ferrero M, Riberi E, Casari G, Altruda F, Turco E, Gasparre G, Battersby BJ, Porcelli AM, Ferrero E, Brusco A, Tempia F. Mice harbouring a SCA28 patient mutation in AFG3L2 develop late-onset ataxia associated with enhanced mitochondrial proteotoxicity. Neurobiol Dis 2018; 124:14-28. [PMID: 30389403 DOI: 10.1016/j.nbd.2018.10.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/05/2018] [Accepted: 10/28/2018] [Indexed: 12/20/2022] Open
Abstract
Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m-AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but adult mice showed signs of cerebellar ataxia detectable by beam test. Although cerebellar pathology was negative, electrophysiological analysis showed a trend towards increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was altered, with greatly reduced expression of fusogenic Opa1 isoforms. Mitochondrial alterations were also detected in cerebella of 18-month-old heterozygous mutants and may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development.
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Affiliation(s)
- Cecilia Mancini
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Eriola Hoxha
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnologies (FABIT), University of Bologna, Bologna, Italy
| | | | - Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Francesca Montarolo
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Claudia Cagnoli
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Roberta Parolisi
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Diana Iulia Gondor Morosini
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Valentina Nicolò
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Francesca Maltecca
- Università Vita-Salute San Raffaele, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Luisa Muratori
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy; Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Giulia Ronchi
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy; Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Stefano Geuna
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy; Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Francesca Arnaboldi
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Elena Donetti
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Elisa Giorgio
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Simona Cavalieri
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Eleonora Di Gregorio
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, Italy
| | - Elisa Pozzi
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Marta Ferrero
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Evelise Riberi
- Department of Public Health and Pediatrics, University of Torino, Torino, Italy
| | - Giorgio Casari
- Università Vita-Salute San Raffaele, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Fiorella Altruda
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Emilia Turco
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Giuseppe Gasparre
- Department Medical and Surgical Sciences, Medical Genetics, University of Bologna, Bologna, Italy
| | | | - Anna Maria Porcelli
- Department of Pharmacy and Biotechnologies (FABIT), University of Bologna, Bologna, Italy
| | - Enza Ferrero
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Torino, Italy; Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, Italy.
| | - Filippo Tempia
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
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11
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Consolato F, Maltecca F, Tulli S, Sambri I, Casari G. m-AAA and i-AAA complexes coordinate to regulate OMA1, the stress-activated supervisor of mitochondrial dynamics. J Cell Sci 2018; 131:jcs.213546. [PMID: 29545505 DOI: 10.1242/jcs.213546] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 03/13/2018] [Indexed: 12/13/2022] Open
Abstract
The proteolytic processing of dynamin-like GTPase OPA1, mediated by the activity of both YME1L1 [intermembrane (i)-AAA protease complex] and OMA1, is a crucial step in the regulation of mitochondrial dynamics. OMA1 is a zinc metallopeptidase of the inner mitochondrial membrane that undergoes pre-activating proteolytic and auto-proteolytic cleavage after mitochondrial import. Here, we identify AFG3L2 [matrix (m)-AAA complex] as the major protease mediating this event, which acts by maturing the 60 kDa pre-pro-OMA1 to the 40 kDa pro-OMA1 form by severing the N-terminal portion without recognizing a specific consensus sequence. Therefore, m-AAA and i-AAA complexes coordinately regulate OMA1 processing and turnover, and consequently control which OPA1 isoforms are present, thus adding new information on the molecular mechanisms of mitochondrial dynamics and neurodegenerative diseases affected by these phenomena.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Francesco Consolato
- Vita-Salute San Raffaele University and Neurogenomics Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milano MI, Italy
| | - Francesca Maltecca
- Vita-Salute San Raffaele University and Neurogenomics Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milano MI, Italy
| | - Susanna Tulli
- Vita-Salute San Raffaele University and Neurogenomics Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milano MI, Italy
| | - Irene Sambri
- Genomic Medicine Program, Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli NA, Italy
| | - Giorgio Casari
- Vita-Salute San Raffaele University and Neurogenomics Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milano MI, Italy .,Genomic Medicine Program, Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli NA, Italy
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12
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Duncan EJ, Larivière R, Bradshaw TY, Longo F, Sgarioto N, Hayes MJ, Romano LEL, Nethisinghe S, Giunti P, Bruntraeger MB, Durham HD, Brais B, Maltecca F, Gentil BJ, Chapple JP. Altered organization of the intermediate filament cytoskeleton and relocalization of proteostasis modulators in cells lacking the ataxia protein sacsin. Hum Mol Genet 2018; 26:3130-3143. [PMID: 28535259 PMCID: PMC5886247 DOI: 10.1093/hmg/ddx197] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/16/2017] [Indexed: 01/09/2023] Open
Abstract
Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) is caused by mutations in the gene SACS, encoding the 520 kDa protein sacsin. Although sacsin’s physiological role is largely unknown, its sequence domains suggest a molecular chaperone or protein quality control function. Consequences of its loss include neurofilament network abnormalities, specifically accumulation and bundling of perikaryal and dendritic neurofilaments. To investigate if loss of sacsin affects intermediate filaments more generally, the distribution of vimentin was analysed in ARSACS patient fibroblasts and in cells where sacsin expression was reduced. Abnormal perinuclear accumulation of vimentin filaments, which sometimes had a cage-like appearance, occurred in sacsin-deficient cells. Mitochondria and other organelles were displaced to the periphery of vimentin accumulations. Reorganization of the vimentin network occurs in vitro under stress conditions, including when misfolded proteins accumulate. In ARSACS patient fibroblasts HSP70, ubiquitin and the autophagy-lysosome pathway proteins Lamp2 and p62 relocalized to the area of the vimentin accumulation. There was no overall increase in ubiquitinated proteins, suggesting the ubiquitin–proteasome system was not impaired. There was evidence for alterations in the autophagy–lysosome pathway. Specifically, in ARSACS HDFs cellular levels of Lamp2 were elevated while levels of p62, which is degraded in autophagy, were decreased. Moreover, autophagic flux was increased in ARSACS HDFs under starvation conditions. These data show that loss of sacsin effects the organization of intermediate filaments in multiple cell types, which impacts the cellular distribution of other organelles and influences autophagic activity.
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Affiliation(s)
- Emma J Duncan
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
| | - Roxanne Larivière
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Teisha Y Bradshaw
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
| | - Fabiana Longo
- Università Vita-Salute San Raffaele and Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy.,Università degli Studi dell'Insubria, Varese, Italy
| | - Nicolas Sgarioto
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | | | - Lisa E L Romano
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
| | - Suran Nethisinghe
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
| | - Paola Giunti
- Department of Molecular Neuroscience, UCL Institute of Neurology, London WC1N 3BG, UK
| | - Michaela B Bruntraeger
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
| | - Heather D Durham
- Laboratory of Neurogenetics of Motion, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Francesca Maltecca
- Università Vita-Salute San Raffaele and Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Benoit J Gentil
- Laboratory of Neurogenetics of Motion, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - J Paul Chapple
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
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13
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Maltecca F, Baseggio E, Consolato F, Mazza D, Podini P, Young SM, Drago I, Bahr BA, Puliti A, Codazzi F, Quattrini A, Casari G. Purkinje neuron Ca2+ influx reduction rescues ataxia in SCA28 model. J Clin Invest 2014; 125:263-74. [PMID: 25485680 DOI: 10.1172/jci74770] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 11/06/2014] [Indexed: 12/11/2022] Open
Abstract
Spinocerebellar ataxia type 28 (SCA28) is a neurodegenerative disease caused by mutations of the mitochondrial protease AFG3L2. The SCA28 mouse model, which is haploinsufficient for Afg3l2, exhibits a progressive decline in motor function and displays dark degeneration of Purkinje cells (PC-DCD) of mitochondrial origin. Here, we determined that mitochondria in cultured Afg3l2-deficient PCs ineffectively buffer evoked Ca²⁺ peaks, resulting in enhanced cytoplasmic Ca²⁺ concentrations, which subsequently triggers PC-DCD. This Ca²⁺-handling defect is the result of negative synergism between mitochondrial depolarization and altered organelle trafficking to PC dendrites in Afg3l2-mutant cells. In SCA28 mice, partial genetic silencing of the metabotropic glutamate receptor mGluR1 decreased Ca²⁺ influx in PCs and reversed the ataxic phenotype. Moreover, administration of the β-lactam antibiotic ceftriaxone, which promotes synaptic glutamate clearance, thereby reducing Ca²⁺ influx, improved ataxia-associated phenotypes in SCA28 mice when given either prior to or after symptom onset. Together, the results of this study indicate that ineffective mitochondrial Ca²⁺ handling in PCs underlies SCA28 pathogenesis and suggest that strategies that lower glutamate stimulation of PCs should be further explored as a potential treatment for SCA28 patients.
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14
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Magnoni R, Palmfeldt J, Christensen JH, Sand M, Maltecca F, Corydon TJ, West M, Casari G, Bross P. Late onset motoneuron disorder caused by mitochondrial Hsp60 chaperone deficiency in mice. Neurobiol Dis 2013; 54:12-23. [PMID: 23466696 DOI: 10.1016/j.nbd.2013.02.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 01/29/2013] [Accepted: 02/22/2013] [Indexed: 01/07/2023] Open
Abstract
Cells rely on efficient protein quality control systems (PQCs) to maintain proper activity of mitochondrial proteins. As part of this system, the mitochondrial chaperone Hsp60 assists folding of matrix proteins and it is an essential protein in all organisms. Mutations in Hspd1, the gene encoding Hsp60, are associated with two human inherited diseases of the nervous system, a dominantly inherited form of spastic paraplegia (SPG13) and an autosomal recessively inherited white matter disorder termed MitCHAP60 disease. Although the connection between mitochondrial failure and neurodegeneration is well known in many neurodegenerative disorders, such as Huntington's disease, Parkinson's disease, and hereditary spastic paraplegia, the molecular basis of the neurodegeneration associated with these diseases is still ill-defined. Here, we investigate mice heterozygous for a knockout allele of the Hspd1 gene encoding Hsp60. Our results demonstrate that Hspd1 haploinsufficiency is sufficient to cause a late onset and slowly progressive deficit in motor functions in mice. We furthermore emphasize the crucial role of the Hsp60 chaperone in mitochondrial function by showing that the motor phenotype is associated with morphological changes of mitochondria, deficient ATP synthesis, and in particular, a defect in the assembly of the respiratory chain complex III in neuronal tissues. In the current study, we propose that our heterozygous Hsp60 mouse model is a valuable model system for the investigation of the link between mitochondrial dysfunction and neurodegeneration.
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Affiliation(s)
- Raffaella Magnoni
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Health Aarhus University Hospital and Aarhus University, Aarhus, Denmark.
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15
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Maltecca F, De Stefani D, Cassina L, Consolato F, Wasilewski M, Scorrano L, Rizzuto R, Casari G. Respiratory dysfunction by AFG3L2 deficiency causes decreased mitochondrial calcium uptake via organellar network fragmentation. Hum Mol Genet 2012; 21:3858-70. [PMID: 22678058 PMCID: PMC3412383 DOI: 10.1093/hmg/dds214] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 05/29/2012] [Indexed: 11/28/2022] Open
Abstract
The mitochondrial protein AFG3L2 forms homo-oligomeric and hetero-oligomeric complexes with paraplegin in the inner mitochondrial membrane, named m-AAA proteases. These complexes are in charge of quality control of misfolded proteins and participate in the regulation of OPA1 proteolytic cleavage, required for mitochondrial fusion. Mutations in AFG3L2 cause spinocerebellar ataxia type 28 and a complex neurodegenerative syndrome of childhood. In this study, we demonstrated that the loss of AFG3L2 in mouse embryonic fibroblasts (MEFs) reduces mitochondrial Ca(2+) uptake capacity. This defect is neither a consequence of global alteration in cellular Ca(2+) homeostasis nor of the reduced driving force for Ca(2+) internalization within mitochondria, since cytosolic Ca(2+) transients and mitochondrial membrane potential remain unaffected. Moreover, experiments in permeabilized cells revealed unaltered mitochondrial Ca(2+) uptake speed in Afg3l2(-/-) cells, indicating the presence of functional Ca(2+) uptake machinery. Our results show that the defective Ca(2+) handling in Afg3l2(-/-) cells is caused by fragmentation of the mitochondrial network, secondary to respiratory dysfunction and the consequent processing of OPA1. This leaves a number of mitochondria devoid of connections to the ER and thus without Ca(2+) elevations, hampering the proper Ca(2+) diffusion along the mitochondrial network. The recovery of mitochondrial fragmentation in Afg3l2(-/-) MEFs by overexpression of OPA1 rescues the impaired mitochondrial Ca(2+) buffering, but fails to restore respiration. By linking mitochondrial morphology and Ca(2+) homeostasis, these findings shed new light in the molecular mechanisms underlining neurodegeneration caused by AFG3L2 mutations.
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Affiliation(s)
- Francesca Maltecca
- San Raffaele Scientific Institute, Vita-Salute San Raffaele University and Center for Translational Genomics and Bioinformatics, Milan-I, Italy
| | - Diego De Stefani
- Department of Biomedical Sciences, University of Padova, Padova-I, Italy
| | - Laura Cassina
- San Raffaele Scientific Institute, Vita-Salute San Raffaele University and Center for Translational Genomics and Bioinformatics, Milan-I, Italy
- Department of Genetics, Biology and Biochemistry, University of Turin, Turin-I, Italy
| | - Francesco Consolato
- San Raffaele Scientific Institute, Vita-Salute San Raffaele University and Center for Translational Genomics and Bioinformatics, Milan-I, Italy
- PhD school of Neurobiology, University of Insubria, Varese-I, Italy
| | - Michal Wasilewski
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Genève-CH, Switzerland and Dulbecco-Telethon Institute, Padova-I, Italy
| | - Luca Scorrano
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Genève-CH, Switzerland and Dulbecco-Telethon Institute, Padova-I, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Padova-I, Italy
| | - Giorgio Casari
- San Raffaele Scientific Institute, Vita-Salute San Raffaele University and Center for Translational Genomics and Bioinformatics, Milan-I, Italy
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16
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Bruni AC, Takahashi-Fujigasaki J, Maltecca F, Foncin JF, Servadio A, Casari G, D'Adamo P, Maletta R, Curcio SAM, De Michele G, Filla A, El Hachimi KH, Duyckaerts C. Behavioral disorder, dementia, ataxia, and rigidity in a large family with TATA box-binding protein mutation. ACTA ACUST UNITED AC 2004; 61:1314-20. [PMID: 15313853 DOI: 10.1001/archneur.61.8.1314] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Spinocerebellar ataxia type 17 is an autosomal dominant cerebellar ataxia caused by a CAG repeat expansion in the TATA box-binding protein gene. Ataxia is typically the first sign whereas behavioral symptoms occur later. OBJECTIVE To characterize the unusual phenotypic expression of a large spinocerebellar ataxia type 17 kindred. DESIGN Clinical, neuropathological, and molecular genetic characterization of a 4-generation family with 16 affected patients. RESULTS Behavioral symptoms and frontal impairment dominated the early stages preceding ataxia, rigidity, and dystonic movements. Neuropathological examination showed cortical, subcortical, and cerebellar atrophy. Purkinje cell loss and gliosis, pseudohypertrophic degeneration of the inferior olive, marked neuronal loss and gliosis in the caudate nucleus, and in the medial thalamic nuclei were salient features together with neuronal intranuclear inclusions stained with anti-TATA box-binding protein and antipolyglutamine antibodies. The disease was caused by a stable 52 CAG repeat expansion of the TATA box-binding protein gene, although there was apparent variability in the age of onset. CONCLUSION The characteristics of this family broaden the clinical picture of spinocerebellar ataxia type 17: initial presenile dementia with behavioral symptoms should be added to ataxia, rigidity, and dystonic movements, which are more commonly encountered.
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17
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De Michele G, Maltecca F, Carella M, Volpe G, Orio M, De Falco A, Gombia S, Servadio A, Casari G, Filla A, Bruni A. Dementia, ataxia, extrapyramidal features, and epilepsy: phenotype spectrum in two Italian families with spinocerebellar ataxia type 17. Neurol Sci 2004; 24:166-7. [PMID: 14598069 DOI: 10.1007/s10072-003-0112-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We observed two families with a dominantly inherited complex neurological syndrome with onset in adulthood. Family F included 9 affected in four generations. One patient showed prominent anticipation of onset age. Onset was with cerebellar signs followed by dementia, psychiatric symptoms, seizures, and extrapyramidal features. Family M included 14 affected individuals in five generations. Presenting symptoms were either psychiatric and cognitive impairment or a cerebellar syndrome. Extrapyramidal features, dysphagia, incontinence, seizures, and myoclonus may occur. In both families magnetic resonance imaging showed marked atrophy of the brain and cerebellum. Molecular analyses demonstrated an expanded CAG/CAA repeat in the in the TATA box-binding protein (TBP) gene (SCA17).
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Affiliation(s)
- G De Michele
- Dipartimento di Scienze Neurologiche, Università Federico II, via Pansini 5, Naples, Italy
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18
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Maltecca F, Filla A, Castaldo I, Coppola G, Fragassi NA, Carella M, Bruni A, Cocozza S, Casari G, Servadio A, De Michele G. Intergenerational instability and marked anticipation in SCA-17. Neurology 2003; 61:1441-3. [PMID: 14638975 DOI: 10.1212/01.wnl.0000094123.09098.a0] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The authors describe an Italian family with autosomal dominant ataxia, dementia, psychiatric and extrapyramidal features, epilepsy, mild sensorimotor axonal neuropathy, and MRI findings of cerebral and cerebellar atrophy. A child had a distinctive presentation with onset at 3 years, growth retardation, fast progression, and early death. Molecular analysis demonstrated an expanded CAG/CAA repeat in the TBP gene (SCA-17). The repeat size was 66 triplets in the child and 53 in all the other patients.
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Affiliation(s)
- F Maltecca
- San Raffaele Scientific Institute (DIBIT), Milan, Italy
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Maltecca F, Spirgi M, Berta JJ, Pouezat JR, Chevrolet S, Metral J. [Modified Hanau technic. Setting up of teeth. Modified occlusal systematization (by the Lauritzen technic). 3]. Rass Odontotec 1971; 18:19-27. [PMID: 5292444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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