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Lopriore P, Palermo G, Meli A, Bellini G, Benevento E, Montano V, Siciliano G, Mancuso M, Ceravolo R. Mitochondrial Parkinsonism: A Practical Guide to Genes and Clinical Diagnosis. Mov Disord Clin Pract 2024. [PMID: 38943319 DOI: 10.1002/mdc3.14148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 04/19/2024] [Accepted: 06/01/2024] [Indexed: 07/01/2024] Open
Abstract
BACKGROUND Primary mitochondrial diseases (PMDs) are the most common inborn errors of energy metabolism, with a combined prevalence of 1 in 4300. They can result from mutations in either nuclear DNA (nDNA) or mitochondrial DNA (mtDNA). These disorders are multisystemic and mainly affect high energy-demanding tissues, such as muscle and the central nervous system (CNS). Among many clinical features of CNS involvement, parkinsonism is one of the most common movement disorders in PMDs. METHODS This review provides a pragmatic educational overview of the most recent advances in the field of mitochondrial parkinsonism, from pathophysiology and genetic etiologies to phenotype and diagnosis. RESULTS mtDNA maintenance and mitochondrial dynamics alterations represent the principal mechanisms underlying mitochondrial parkinsonism. It can be present in isolation, alongside other movement disorders or, more commonly, as part of a multisystemic phenotype. Mutations in several nuclear-encoded genes (ie, POLG, TWNK, SPG7, and OPA1) and, more rarely, mtDNA mutations, are responsible for mitochondrial parkinsonism. Progressive external opthalmoplegia and optic atrophy may guide genetic etiology identification. CONCLUSION A comprehensive deep-phenotyping approach is needed to reach a diagnosis of mitochondrial parkinsonism, which lacks distinctive clinical features and exemplifies the intricate genotype-phenotype interplay of PMDs.
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Affiliation(s)
- Piervito Lopriore
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Giovanni Palermo
- Unit of Neurology, Department of Clinical and Experimental Medicine, Center for Neurodegenerative Diseases-Parkinson's Disease and Movement Disorders, University of Pisa, Pisa, Italy
| | - Adriana Meli
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Gabriele Bellini
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- Unit of Neurology, Department of Clinical and Experimental Medicine, Center for Neurodegenerative Diseases-Parkinson's Disease and Movement Disorders, University of Pisa, Pisa, Italy
| | - Elena Benevento
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- Unit of Neurology, Department of Clinical and Experimental Medicine, Center for Neurodegenerative Diseases-Parkinson's Disease and Movement Disorders, University of Pisa, Pisa, Italy
| | - Vincenzo Montano
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Gabriele Siciliano
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Michelangelo Mancuso
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Roberto Ceravolo
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- Unit of Neurology, Department of Clinical and Experimental Medicine, Center for Neurodegenerative Diseases-Parkinson's Disease and Movement Disorders, University of Pisa, Pisa, Italy
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Fasano A, Jinnah HA. Describing Clinical Features of Movement Disorders for Effective Research Reporting. Mov Disord Clin Pract 2024. [PMID: 39030741 DOI: 10.1002/mdc3.14140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 05/24/2024] [Accepted: 05/25/2024] [Indexed: 07/22/2024] Open
Affiliation(s)
- Alfonso Fasano
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, UHN, Toronto, Ontario, Canada
- Division of Neurology, University of Toronto, Toronto, Ontario, Canada
- Krembil Brain Institute, Toronto, Ontario, Canada
| | - Hyder A Jinnah
- Department of Neurology, Human Genetics, and Pediatrics; Emory University School of Medicine, Atlanta, Georgia, USA
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Del Greco C, Antonellis A. The Role of Nuclear-Encoded Mitochondrial tRNA Charging Enzymes in Human Inherited Disease. Genes (Basel) 2022; 13:2319. [PMID: 36553587 PMCID: PMC9777667 DOI: 10.3390/genes13122319] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are highly conserved essential enzymes that charge tRNA with cognate amino acids-the first step of protein synthesis. Of the 37 nuclear-encoded human ARS genes, 17 encode enzymes are exclusively targeted to the mitochondria (mt-ARSs). Mutations in nuclear mt-ARS genes are associated with rare, recessive human diseases with a broad range of clinical phenotypes. While the hypothesized disease mechanism is a loss-of-function effect, there is significant clinical heterogeneity among patients that have mutations in different mt-ARS genes and also among patients that have mutations in the same mt-ARS gene. This observation suggests that additional factors are involved in disease etiology. In this review, we present our current understanding of diseases caused by mutations in the genes encoding mt-ARSs and propose explanations for the observed clinical heterogeneity.
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Affiliation(s)
- Christina Del Greco
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Abstract
The human brain consumes five orders of magnitude more energy than the sun by unit of mass and time. This staggering bioenergetic cost serves mostly synaptic transmission and actin cytoskeleton dynamics. The peak of both brain bioenergetic demands and the age of onset for neurodevelopmental disorders is approximately 5 years of age. This correlation suggests that defects in the machinery that provides cellular energy would be causative and/or consequence of neurodevelopmental disorders. We explore this hypothesis from the perspective of the machinery required for the synthesis of the electron transport chain, an ATP-producing and NADH-consuming enzymatic cascade. The electron transport chain is constituted by nuclear- and mitochondrial-genome-encoded subunits. These subunits are synthesized by the 80S and the 55S ribosomes, which are segregated to the cytoplasm and the mitochondrial matrix, correspondingly. Mitochondrial protein synthesis by the 55S ribosome is the rate-limiting step in the synthesis of electron transport chain components, suggesting that mitochondrial protein synthesis is a bottleneck for tissues with high bionergetic demands. We discuss genetic defects in the human nuclear and mitochondrial genomes that affect these protein synthesis machineries and cause a phenotypic spectrum spanning autism spectrum disorders to neurodegeneration during neurodevelopment. We propose that dysregulated mitochondrial protein synthesis is a chief, yet understudied, causative mechanism of neurodevelopmental and behavioral disorders.
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Blaze J, Akbarian S. The tRNA regulome in neurodevelopmental and neuropsychiatric disease. Mol Psychiatry 2022; 27:3204-3213. [PMID: 35505091 PMCID: PMC9630165 DOI: 10.1038/s41380-022-01585-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 04/11/2022] [Accepted: 04/13/2022] [Indexed: 12/14/2022]
Abstract
Transfer (t)RNAs are 70-90 nucleotide small RNAs highly regulated by 43 different types of epitranscriptomic modifications and requiring aminoacylation ('charging') for mRNA decoding and protein synthesis. Smaller cleavage products of mature tRNAs, or tRNA fragments, have been linked to a broad variety of noncanonical functions, including translational inhibition and modulation of the immune response. Traditionally, knowledge about tRNA regulation in brain is derived from phenotypic exploration of monogenic neurodevelopmental and neurodegenerative diseases associated with rare mutations in tRNA modification genes. More recent studies point to the previously unrecognized potential of the tRNA regulome to affect memory, synaptic plasticity, and affective states. For example, in mature cortical neurons, cytosine methylation sensitivity of the glycine tRNA family (tRNAGly) is coupled to glycine biosynthesis and codon-specific alterations in ribosomal translation together with robust changes in cognition and depression-related behaviors. In this Review, we will discuss the emerging knowledge of the neuronal tRNA landscape, with a focus on epitranscriptomic tRNA modifications and downstream molecular pathways affected by alterations in tRNA expression, charging levels, and cleavage while mechanistically linking these pathways to neuropsychiatric disease and provide insight into future areas of study for this field.
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Affiliation(s)
- Jennifer Blaze
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA. .,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Schahram Akbarian
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA,Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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