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Shieh JT, Tintos-Hernandez JA, Murali CN, Penon-Portmann M, Flores-Mendez M, Santana A, Bulos JA, Du K, Dupuis L, Damseh N, Mendoza-Londoño R, Berera C, Lee JC, Phillips JJ, Alves CAPF, Dmochowski IJ, Ortiz-González XR. Heterozygous nonsense variants in the ferritin heavy-chain gene FTH1 cause a neuroferritinopathy. HGG ADVANCES 2023; 4:100236. [PMID: 37660254 PMCID: PMC10510067 DOI: 10.1016/j.xhgg.2023.100236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 09/04/2023] Open
Abstract
Ferritin, the iron-storage protein, is composed of light- and heavy-chain subunits, encoded by FTL and FTH1, respectively. Heterozygous variants in FTL cause hereditary neuroferritinopathy, a type of neurodegeneration with brain iron accumulation (NBIA). Variants in FTH1 have not been previously associated with neurologic disease. We describe the clinical, neuroimaging, and neuropathology findings of five unrelated pediatric patients with de novo heterozygous FTH1 variants. Children presented with developmental delay, epilepsy, and progressive neurologic decline. Nonsense FTH1 variants were identified using whole-exome sequencing, with a recurrent variant (p.Phe171∗) identified in four unrelated individuals. Neuroimaging revealed diffuse volume loss, features of pontocerebellar hypoplasia, and iron accumulation in the basal ganglia. Neuropathology demonstrated widespread ferritin inclusions in the brain. Patient-derived fibroblasts were assayed for ferritin expression, susceptibility to iron accumulation, and oxidative stress. Variant FTH1 mRNA transcripts escape nonsense-mediated decay (NMD), and fibroblasts show elevated ferritin protein levels, markers of oxidative stress, and increased susceptibility to iron accumulation. C-terminal variants in FTH1 truncate ferritin's E helix, altering the 4-fold symmetric pores of the heteropolymer, and likely diminish iron-storage capacity. FTH1 pathogenic variants appear to act by a dominant, toxic gain-of-function mechanism. The data support the conclusion that truncating variants in the last exon of FTH1 cause a disorder in the spectrum of NBIA. Targeted knockdown of mutant FTH1 transcript with antisense oligonucleotides rescues cellular phenotypes and suggests a potential therapeutic strategy for this pediatric neurodegenerative disorder.
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Affiliation(s)
- Joseph T Shieh
- Institute for Human Genetics and Department of Pediatrics, University of California San Francisco, San Francisco, CA 94143, USA.
| | - Jesus A Tintos-Hernandez
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Chaya N Murali
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Monica Penon-Portmann
- Institute for Human Genetics and Department of Pediatrics, University of California San Francisco, San Francisco, CA 94143, USA
| | - Marco Flores-Mendez
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Adrian Santana
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Joshua A Bulos
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kang Du
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lucie Dupuis
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - Nadirah Damseh
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - Roberto Mendoza-Londoño
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - Camilla Berera
- Institute for Human Genetics and Department of Pediatrics, University of California San Francisco, San Francisco, CA 94143, USA
| | - Julieann C Lee
- Division of Neuropathology, Department of Pathology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Joanna J Phillips
- Division of Neuropathology, Department of Pathology, University of California San Francisco, San Francisco, CA 94143, USA; Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94143, USA
| | - César A P F Alves
- Division of Neuroradiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Ivan J Dmochowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xilma R Ortiz-González
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Epilepsy Neurogenetics Initiative (ENGIN), The Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Shieh JT, Tintos-Hernández JA, Murali CN, Penon-Portmann M, Flores-Mendez M, Santana A, Bulos JA, Du K, Dupuis L, Damseh N, Mendoza-Londoño R, Berera C, Lee JC, Phillips JJ, Alves CAPF, Dmochowski IJ, Ortiz-González XR. Heterozygous Nonsense Variants in the Ferritin Heavy Chain Gene FTH1 Cause a Novel Pediatric Neuroferritinopathy. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.01.30.23285099. [PMID: 36778397 PMCID: PMC9915813 DOI: 10.1101/2023.01.30.23285099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ferritin, the iron storage protein, is composed of light and heavy chain subunits, encoded by FTL and FTH1 , respectively. Heterozygous variants in FTL cause hereditary neuroferritinopathy, a type of neurodegeneration with brain iron accumulation (NBIA). Variants in FTH1 have not been previously associated with neurologic disease. We describe the clinical, neuroimaging, and neuropathology findings of five unrelated pediatric patients with de novo heterozygous FTH1 variants. Children presented with developmental delay, epilepsy, and progressive neurologic decline. Nonsense FTH1 variants were identified using whole exome sequencing, with a recurrent de novo variant (p.F171*) identified in three unrelated individuals. Neuroimaging revealed diffuse volume loss, features of pontocerebellar hypoplasia and iron accumulation in the basal ganglia. Neuropathology demonstrated widespread ferritin inclusions in the brain. Patient-derived fibroblasts were assayed for ferritin expression, susceptibility to iron accumulation, and oxidative stress. Variant FTH1 mRNA transcripts escape nonsense-mediated decay (NMD), and fibroblasts show elevated ferritin protein levels, markers of oxidative stress, and increased susceptibility to iron accumulation. C-terminus variants in FTH1 truncate ferritin's E-helix, altering the four-fold symmetric pores of the heteropolymer and likely diminish iron-storage capacity. FTH1 pathogenic variants appear to act by a dominant, toxic gain-of-function mechanism. The data support the conclusion that truncating variants in the last exon of FTH1 cause a novel disorder in the spectrum of NBIA. Targeted knock-down of mutant FTH1 transcript with antisense oligonucleotides rescues cellular phenotypes and suggests a potential therapeutic strategy for this novel pediatric neurodegenerative disorder.
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Affiliation(s)
- Joseph T Shieh
- Institute for Human Genetics and Department of Pediatrics, University of California San Francisco, CA, 94143
- These authors contributed equally to this work
| | - Jesus A Tintos-Hernández
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104
- These authors contributed equally to this work
| | - Chaya N. Murali
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Monica Penon-Portmann
- Institute for Human Genetics and Department of Pediatrics, University of California San Francisco, CA, 94143
| | - Marco Flores-Mendez
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104
| | - Adrian Santana
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104
| | - Joshua A. Bulos
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Kang Du
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Lucie Dupuis
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Canada
| | - Nadirah Damseh
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Canada
| | - Roberto Mendoza-Londoño
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Canada
| | - Camilla Berera
- Institute for Human Genetics and Department of Pediatrics, University of California San Francisco, CA, 94143
| | - Julieann C Lee
- Division of Neuropathology, Department of Pathology, University of California San Francisco, CA, 94143
| | - Joanna J Phillips
- Division of Neuropathology, Department of Pathology, University of California San Francisco, CA, 94143
- Department of Neurological Surgery, University of California San Francisco, CA, 94143
| | - César A P F Alves
- Division of Neuroradiology, Department of Pediatrics, The Children’s Hospital of Philadelphia
| | - Ivan J Dmochowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Xilma R Ortiz-González
- Division of Neurology and Center for Mitochondrial and Epigenomic Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104
- Epilepsy Neurogenetics Initiative (ENGIN), The Children’s Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104
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Jellinger KA. Pallidal degenerations and related disorders: an update. J Neural Transm (Vienna) 2021; 129:521-543. [PMID: 34363531 DOI: 10.1007/s00702-021-02392-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/22/2021] [Indexed: 11/26/2022]
Abstract
Neurodegenerative disorders involving preferentially the globus pallidus, its efferet and afferent circuits and/or related neuronal systems are rare. They include a variety of both familial and sporadic progressive movement disorders, clinically manifesting as choreoathetosis, dystonia, Parkinsonism, akinesia or myoclonus, often associated with seizures, mental impairment and motor or cerebellar symptoms. Based on the involved neuronal systems, this heterogenous group has been classified into several subgroups: "pure" pallidal atrophy (PPA) and extended forms, pallidonigral and pallidonigrospinal degeneration (PND, PNSD), pallidopyramidal syndrome (PPS), a highly debatable group, pallidopontonigral (PPND), nigrostriatal-pallidal-pyramidal degeneration (NSPPD) (Kufor-Rakeb syndrome /KRS), pallidoluysian degeneration (PLD), pallidoluysionigral degeneration (PLND), pallidoluysiodentate atrophy (PLDA), the more frequent dentatorubral-pallidoluysian atrophy (DRPLA), and other hereditary multisystem disorders affecting these systems, e.g., neuroferritinopathy (NF). Some of these syndromes are sporadic, others show autosomal recessive or dominant heredity, and for some specific gene mutations have been detected, e.g., ATP13A2/PARK9 (KRS), FTL1 or ATP13A2 (neuroferritinopathy), CAG triple expansions in gene ATN1 (DRPLA) or pA152T variant in MAPT gene (PNLD). One of the latter, and both PPND and DRPLA are particular subcortical 4-R tauopathies, related to progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and frontotemporal lobe degeneration-17 (FTLD-17), while others show additional 3-R and 4-R tauopathies or TDP-43 pathologies. The differential diagnosis includes a large variety of neurodegenerations ranging from Huntington and Joseph-Machado disease, tauopathies (PSP), torsion dystonia, multiple system atrophy, neurodegeneration with brain iron accumulation (NBIA), and other extrapyramidal disorders. Neuroimaging data and biological markers have been published for only few syndromes. In the presence of positive family histories, an early genetic counseling may be effective. The etiology of most phenotypes is unknown, and only for some pathogenic mechanisms, like polyglutamine-induced oxidative stress and autophagy in DRPLA, mitochondrial dysfunction induced by oxidative stress in KRS or ferrostasis/toxicity and protein aggregation in NF, have been discussed. Currently no disease-modifying therapy is available, and symptomatic treatment of hypo-, hyperkinetic, spastic or other symptoms may be helpful.
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Affiliation(s)
- Kurt A Jellinger
- Institute of Clinical Neurobiology, Alberichgasse 5/13, 1150, Vienna, Austria.
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4
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Cozzi A, Santambrogio P, Ripamonti M, Rovida E, Levi S. Pathogenic mechanism and modeling of neuroferritinopathy. Cell Mol Life Sci 2021; 78:3355-3367. [PMID: 33439270 PMCID: PMC11072144 DOI: 10.1007/s00018-020-03747-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 12/26/2022]
Abstract
Neuroferritinopathy is a rare autosomal dominant inherited movement disorder caused by alteration of the L-ferritin gene that results in the production of a ferritin molecule that is unable to properly manage iron, leading to the presence of free redox-active iron in the cytosol. This form of iron has detrimental effects on cells, particularly severe for neuronal cells, which are highly sensitive to oxidative stress. Although very rare, the disorder is notable for two reasons. First, neuroferritinopathy displays features also found in a larger group of disorders named Neurodegeneration with Brain Iron Accumulation (NBIA), such as iron deposition in the basal ganglia and extrapyramidal symptoms; thus, the elucidation of its pathogenic mechanism may contribute to clarifying the incompletely understood aspects of NBIA. Second, neuroferritinopathy shows the characteristic signs of an accelerated process of aging; thus, it can be considered an interesting model to study the progress of aging. Here, we will review the clinical and neurological features of neuroferritinopathy and summarize biochemical studies and data from cellular and animal models to propose a pathogenic mechanism of the disorder.
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Affiliation(s)
- Anna Cozzi
- Proteomic of Iron Metabolism Unit, Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Paolo Santambrogio
- Proteomic of Iron Metabolism Unit, Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Maddalena Ripamonti
- Proteomic of Iron Metabolism Unit, Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Ermanna Rovida
- Institute for Genetic and Biomedical Research, National Research Council, 20138, Milan, Italy
| | - Sonia Levi
- Proteomic of Iron Metabolism Unit, Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy.
- Vita-Salute San Raffaele University and San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy.
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McNally JR, Mehlenbacher MR, Luscieti S, Smith GL, Reutovich AA, Maura P, Arosio P, Bou-Abdallah F. Mutant L-chain ferritins that cause neuroferritinopathy alter ferritin functionality and iron permeability. Metallomics 2020; 11:1635-1647. [PMID: 31513212 DOI: 10.1039/c9mt00154a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In mammals, the iron storage and detoxification protein ferritin is composed of two functionally and genetically distinct subunit types, H (heavy) and L (light). The two subunits co-assemble in various ratios, with a tissue specific distribution, to form shell-like protein structures of 24 subunits within which a mineralized iron core is stored. The H-subunits possess ferroxidase centers that catalyze the rapid oxidation of ferrous ions, whereas the L-subunit does not have such centers and is believed to play an important role in electron transfer reactions that occur during the uptake and release of iron. Pathogenic mutations on the L-chain lead to neuroferritinopathy, a neurodegenerative disease characterized by abnormal accumulation of ferritin inclusion bodies and iron in the central nervous system. Here, we have characterized the thermal stability, iron loading capacity, iron uptake, and iron release properties of ferritin heteropolymers carrying the three pathogenic L-ferritin mutants (L154fs, L167fs, and L148fs, which for simplicity we named Ln1, Ln2 and Ln3, respectively), and a non-pathogenic variant (L135P) bearing a single substitution on the 3-fold axes of L-subunits. The UV-Vis data show a similar iron loading capacity (ranging between 1800 to 2400 Fe(iii)/shell) for all ferritin samples examined in this study, with Ln2 holding the least amount of iron (i.e. 1800 Fe(iii)/shell). The three pathogenic L-ferritin mutants revealed higher rates of iron oxidation and iron release, suggesting that a few mutated L-chains on the heteropolymer have a significant effect on iron permeability through the ferritin shell. DSC thermograms showed a strong destabilization effect, the severity of which depends on the location of the frameshift mutations (i.e. wt heteropolymer ferritin ≅ homopolymer H-chain > L135P > Ln2 > Ln1 > Ln3). Variant L135P had only minor effects on the protein functionality and stability, suggesting that local melting of the 3-fold axes in this variant may not be responsible for neuroferritinopathy-like disorders. The data support the hypothesis that hereditary neuroferritinopathies are due to alterations of ferritin functionality and lower physical stability which correlate with the frameshifts introduced at the C-terminal sequence and explain the dominant transmission of the disorder.
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Affiliation(s)
- Justin R McNally
- Department of Chemistry, State University of New York, Potsdam, New York 13676, USA.
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Neuropathology and pathogenesis of extrapyramidal movement disorders: a critical update. II. Hyperkinetic disorders. J Neural Transm (Vienna) 2019; 126:997-1027. [DOI: 10.1007/s00702-019-02030-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/14/2019] [Indexed: 12/14/2022]
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7
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Iron Pathophysiology in Neurodegeneration with Brain Iron Accumulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1173:153-177. [DOI: 10.1007/978-981-13-9589-5_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Kumar N, Rizek P, Jog M. Neuroferritinopathy: Pathophysiology, Presentation, Differential Diagnoses and Management. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2016; 6:355. [PMID: 27022507 PMCID: PMC4795517 DOI: 10.7916/d8kk9bhf] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/14/2016] [Indexed: 12/20/2022]
Abstract
Background Neuroferritinopathy (NF) is a rare autosomal dominant disease caused by
mutations in the ferritin light chain 1 (FTL1) gene
leading to abnormal excessive iron accumulation in the brain, predominantly in the
basal ganglia. Methods A literature search was performed on Pubmed, for English-language articles,
utilizing the terms iron metabolism, neurodegeneration with brain iron
accumulation, and NF. The relevant articles were reviewed with a focus on the
pathophysiology, clinical presentation, differential diagnoses, and management of
NF. Results There have been nine reported mutations worldwide in the FTL1
gene in 90 patients, the most common mutation being 460InsA. Chorea and dystonia
are the most common presenting symptoms in NF. There are specific features, which
appear to depend upon the genetic mutation. We discuss the occurrence of specific
mutations in various regions along with their associated presenting phenomenology.
We have compared and contrasted the commonly occurring syndromes in the
differential diagnosis of NF to guide the clinician. Discussion NF must be considered in patients presenting clinically as a progressive movement
disorder with variable phenotype and imaging evidence of iron deposition within
the brain, decreased serum ferritin, and negative genetic testing for other more
common movement disorders such as Huntington’s disease. In the absence of a
disease-specific treatment, symptomatic drug therapy for specific movement
disorders may be used, although with variable success.
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Affiliation(s)
- Niraj Kumar
- Department of Clinical Neurological Sciences, Western University, London, ON, Canada
| | - Philippe Rizek
- Department of Clinical Neurological Sciences, Western University, London, ON, Canada
| | - Mandar Jog
- Department of Clinical Neurological Sciences, Western University, London, ON, Canada
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Neuroferritinopathy: From ferritin structure modification to pathogenetic mechanism. Neurobiol Dis 2015; 81:134-43. [PMID: 25772441 PMCID: PMC4642653 DOI: 10.1016/j.nbd.2015.02.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 01/20/2015] [Accepted: 02/05/2015] [Indexed: 12/23/2022] Open
Abstract
Neuroferritinopathy is a rare, late-onset, dominantly inherited movement disorder caused by mutations in L-ferritin gene. It is characterized by iron and ferritin aggregate accumulation in brain, normal or low serum ferritin levels and high variable clinical feature. To date, nine causative mutations have been identified and eight of them are frameshift mutations determined by nucleotide(s) insertion in the exon 4 of L-ferritin gene altering the structural conformation of the C-terminus of the L-ferritin subunit. Acting in a dominant negative manner, mutations are responsible for an impairment of the iron storage efficiency of ferritin molecule. Here, we review the main characteristics of neuroferritinopathy and present a computational analysis of some representative recently defined mutations with the purpose to gain new information about the pathogenetic mechanism of the disorder. This is particularly important as neuroferritinopathy can be considered an interesting model to study the relationship between iron, oxidative stress and neurodegeneration.
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10
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Behavioral characterization of mouse models of neuroferritinopathy. PLoS One 2015; 10:e0118990. [PMID: 25689865 PMCID: PMC4331086 DOI: 10.1371/journal.pone.0118990] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/08/2015] [Indexed: 01/02/2023] Open
Abstract
Ferritin is the main intracellular protein of iron storage with a central role in the regulation of iron metabolism and detoxification. Nucleotide insertions in the last exon of the ferritin light chain cause a neurodegenerative disease known as Neuroferritinopathy, characterized by iron deposition in the brain, particularly in the cerebellum, basal ganglia and motor cortex. The disease progresses relentlessly, leading to dystonia, chorea, motor disability and neuropsychiatry features. The characterization of a good animal model is required to compare and contrast specific features with the human disease, in order to gain new insights on the consequences of chronic iron overload on brain function and behavior. To this aim we studied an animal model expressing the pathogenic human FTL mutant 498InsTC under the phosphoglycerate kinase (PGK) promoter. Transgenic (Tg) mice showed strong accumulation of the mutated protein in the brain, which increased with age, and this was accompanied by brain accumulation of ferritin/iron bodies, the main pathologic hallmark of human neuroferritinopathy. Tg-mice were tested throughout development and aging at 2-, 8- and 18-months for motor coordination and balance (Beam Walking and Footprint tests). The Tg-mice showed a significant decrease in motor coordination at 8 and 18 months of age, with a shorter latency to fall and abnormal gait. Furthermore, one group of aged naïve subjects was challenged with two herbicides (Paraquat and Maneb) known to cause oxidative damage. The treatment led to a paradoxical increase in behavioral activation in the transgenic mice, suggestive of altered functioning of the dopaminergic system. Overall, data indicate that mice carrying the pathogenic FTL498InsTC mutation show motor deficits with a developmental profile suggestive of a progressive pathology, as in the human disease. These mice could be a powerful tool to study the neurodegenerative mechanisms leading to the disease and help developing specific therapeutic targets.
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