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Dong YN, Mercado-Ayón E, Coulman J, Flatley L, Ngaba LV, Adeshina MW, Lynch DR. The Regulation of the Disease-Causing Gene FXN. Cells 2024; 13:1040. [PMID: 38920668 PMCID: PMC11202134 DOI: 10.3390/cells13121040] [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: 05/15/2024] [Revised: 06/10/2024] [Accepted: 06/13/2024] [Indexed: 06/27/2024] Open
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease caused in almost all patients by expanded guanine-adenine-adenine (GAA) trinucleotide repeats within intron 1 of the FXN gene. This results in a relative deficiency of frataxin, a small nucleus-encoded mitochondrial protein crucial for iron-sulfur cluster biogenesis. Currently, there is only one medication, omaveloxolone, available for FRDA patients, and it is limited to patients 16 years of age and older. This necessitates the development of new medications. Frataxin restoration is one of the main strategies in potential treatment options as it addresses the root cause of the disease. Comprehending the control of frataxin at the transcriptional, post-transcriptional, and post-translational stages could offer potential therapeutic approaches for addressing the illness. This review aims to provide a general overview of the regulation of frataxin and its implications for a possible therapeutic treatment of FRDA.
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Affiliation(s)
- Yi Na Dong
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Jennifer Coulman
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Liam Flatley
- The Wharton School, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lucie Vanessa Ngaba
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Miniat W. Adeshina
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R. Lynch
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Luffarelli R, Panarello L, Quatrana A, Tiano F, Fortuni S, Rufini A, Malisan F, Testi R, Condò I. Interferon Gamma Enhances Cytoprotective Pathways via Nrf2 and MnSOD Induction in Friedreich's Ataxia Cells. Int J Mol Sci 2023; 24:12687. [PMID: 37628866 PMCID: PMC10454386 DOI: 10.3390/ijms241612687] [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: 06/08/2023] [Revised: 07/27/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023] Open
Abstract
Friedreich's ataxia (FRDA) is a rare monogenic disease characterized by multisystem, slowly progressive degeneration. Because of the genetic defect in a non-coding region of FXN gene, FRDA cells exhibit severe deficit of frataxin protein levels. Hence, FRDA pathophysiology is characterized by a plethora of metabolic disruptions related to iron metabolism, mitochondrial homeostasis and oxidative stress. Importantly, an impairment of the antioxidant defences exacerbates the oxidative damage. This appears closely associated with the disablement of key antioxidant proteins, such as the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and the mitochondrial superoxide dismutase (MnSOD). The cytokine interferon gamma (IFN-γ) has been shown to increase frataxin expression in FRDA cells and to improve functional deficits in FRDA mice. Currently, IFN-γ represents a potential therapy under clinical evaluation in FRDA patients. Here, we show that IFN-γ induces a rapid expression of Nrf2 and MnSOD in different cell types, including FRDA patient-derived fibroblasts. Our data indicate that IFN-γ signals two separate pathways to enhance Nrf2 and MnSOD levels in FRDA fibroblasts. MnSOD expression increased through an early transcriptional regulation, whereas the levels of Nrf2 are induced by a post-transcriptional mechanism. We demonstrate that the treatment of FRDA fibroblasts with IFN-γ stimulates a non-canonical Nrf2 activation pathway through p21 and potentiates antioxidant responses under exposure to hydrogen peroxide. Moreover, IFN-γ significantly reduced the sensitivity to hydrogen peroxide-induced cell death in FRDA fibroblasts. Collectively, these results indicate the presence of multiple pathways triggered by IFN-γ with therapeutic relevance to FRDA.
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Affiliation(s)
- Riccardo Luffarelli
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Luca Panarello
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Andrea Quatrana
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Francesca Tiano
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Silvia Fortuni
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Alessandra Rufini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
- Departmental Faculty of Medicine and Surgery, Saint Camillus International University of Health and Medical Sciences, 00131 Rome, Italy
| | - Florence Malisan
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Roberto Testi
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
| | - Ivano Condò
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (R.L.); (L.P.); (A.Q.); (F.T.); (S.F.); (A.R.); (F.M.); (R.T.)
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3
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Ramos L. Dimorphic frataxin and its gene regulation by sex steroids in hamsters. Mol Genet Genomics 2023; 298:615-626. [PMID: 36929169 DOI: 10.1007/s00438-023-02004-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 03/03/2023] [Indexed: 03/18/2023]
Abstract
The role of frataxin (FXN) has been studied extensively in Friedreich ataxia patients, however, the molecular bases underlining the sex steroid-dependent gene expression profiles of FXN in adult tissues are unknown. I describe the molecular characterization of hamster FXN by examining the sexually dimorphic expression and its regulation by sex steroids. Sequence analysis of FXN cDNA showed 630 bp-long ORF encoding 209 amino acids. qPCR analysis revealed that FXN is detected in a wide range of tissues, with the highest expression in the heart, liver, and epididymis, and the weakest expression in the lung, spleen, uterus, and gut. In the male Harderian gland (HG), castration decreased FXN expression, while dihydrotestosterone (DHT) administration reestablished levels. FXN expression levels were higher in the male HG than the female HG. Expression levels in endocrine tissues showed a certain degree of sexual dimorphism; the transcript in the testis was significantly higher than those in the ovary. The effects of the estrous cycle on FXN expression remained unchanged in the HG, ovary, and adrenal glands; however, in the pancreas, the FXN mRNA was overexpressed during proestrus and exhibited sexual dimorphism as compared to the male pancreas. The mRNA expression results indicated that Harderian FXN may play a dynamic role in intracellular Fe of heme required for processing cytochromes and other hemeproteins, also suggesting that the moderate sexual dimorphism present in the HG and gonads could be regulated by androgens, while sexually dimorphic expression of FXN in the female pancreas may be controlled by sex steroids.
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Affiliation(s)
- L Ramos
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición, Salvador Zubirán, Av. Vasco de Quiroga #15, Tlalpan, C.P. 14080, México City, México.
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4
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Small-molecule inhibitors of proteasome increase CjCas9 protein stability. PLoS One 2023; 18:e0280353. [PMID: 36656806 PMCID: PMC9851528 DOI: 10.1371/journal.pone.0280353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/27/2022] [Indexed: 01/20/2023] Open
Abstract
The small size of CjCas9 can make easier its vectorization for in vivo gene therapy. However, compared to the SpCas9, the CjCas9 is, in general, less efficient to generate indels in target genes. The factors that affect its efficacity are not yet determined. We observed that the CjCas9 protein expressed in HEK293T cells after transfection of this transgene under a CMV promoter was much lower than the SpCas9 protein in the same conditions. We thus evaluated the effect of proteasome inhibitors on CjCas9 protein stability and its efficiency on FXN gene editing. Western blotting showed that the addition of MG132 or bortezomib, significantly increased CjCas9 protein levels in HEK293T and HeLa cells. Moreover, bortezomib increased the level of CjCas9 protein expressed under promoters weaker than CMV such as CBH or EFS but which are specific for certain tissues. Finally, ddPCR quantification showed that bortezomib treatment enhanced CjCas9 efficiency to delete GAA repeat region of FXN gene in HEK293T cells. The improvement of CjCas9 protein stability would facilitate its used in CRISPR/Cas system.
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Baker MJ, Crameri JJ, Thorburn DR, Frazier AE, Stojanovski D. Mitochondrial biology and dysfunction in secondary mitochondrial disease. Open Biol 2022; 12:220274. [PMID: 36475414 PMCID: PMC9727669 DOI: 10.1098/rsob.220274] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial diseases are a broad, genetically heterogeneous class of metabolic disorders characterized by deficits in oxidative phosphorylation (OXPHOS). Primary mitochondrial disease (PMD) defines pathologies resulting from mutation of mitochondrial DNA (mtDNA) or nuclear genes affecting either mtDNA expression or the biogenesis and function of the respiratory chain. Secondary mitochondrial disease (SMD) arises due to mutation of nuclear-encoded genes independent of, or indirectly influencing OXPHOS assembly and operation. Despite instances of novel SMD increasing year-on-year, PMD is much more widely discussed in the literature. Indeed, since the implementation of next generation sequencing (NGS) techniques in 2010, many novel mitochondrial disease genes have been identified, approximately half of which are linked to SMD. This review will consolidate existing knowledge of SMDs and outline discrete categories within which to better understand the diversity of SMD phenotypes. By providing context to the biochemical and molecular pathways perturbed in SMD, we hope to further demonstrate the intricacies of SMD pathologies outside of their indirect contribution to mitochondrial energy generation.
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Affiliation(s)
- Megan J. Baker
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Jordan J. Crameri
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| | - David R. Thorburn
- Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia,Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Ann E. Frazier
- Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Diana Stojanovski
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
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6
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Hackett PT, Jia X, Li L, Ward DM. Posttranslational regulation of mitochondrial frataxin and identification of compounds that increase frataxin levels in Friedreich's ataxia. J Biol Chem 2022; 298:101982. [PMID: 35472330 PMCID: PMC9127368 DOI: 10.1016/j.jbc.2022.101982] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 11/18/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a degenerative disease caused by a decrease in the mitochondrial protein frataxin (Fxn), which is involved in iron-sulfur cluster (ISC) synthesis. Diminutions in Fxn result in decreased ISC synthesis, increased mitochondrial iron accumulation, and impaired mitochondrial function. Here, we show that conditions that result in increased mitochondrial reactive oxygen species in yeast or mammalian cell culture give rise to increased turnover of Fxn but not of other ISC synthesis proteins. We demonstrate that the mitochondrial Lon protease is involved in Fxn degradation and that iron export through the mitochondrial metal transporter Mmt1 protects yeast Fxn from degradation. We also determined that when FRDA fibroblasts were grown in media containing elevated iron, mitochondrial reactive oxygen species increased and Fxn decreased compared to WT fibroblasts. Furthermore, we screened a library of FDA-approved compounds and identified 38 compounds that increased yeast Fxn levels, including the azole bifonazole, antiparasitic fipronil, antitumor compound dibenzoylmethane, antihypertensive 4-hydroxychalcone, and a nonspecific anion channel inhibitor 4,4-diisothiocyanostilbene-2,2-sulfonic acid. We show that top hits 4-hydroxychalcone and dibenzoylmethane increased mRNA levels of transcription factor nuclear factor erythroid 2-related factor 2 in FRDA patient-derived fibroblasts, as well as downstream antioxidant targets thioredoxin, glutathione reductase, and superoxide dismutase 2. Taken together, these findings reveal that FRDA progression may be in part due to oxidant-mediated decreases in Fxn and that some approved compounds may be effective in increasing mitochondrial Fxn in FRDA, delaying disease progression.
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Affiliation(s)
- Peter T Hackett
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Xuan Jia
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Liangtao Li
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Diane M Ward
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah, USA.
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7
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Rufini A, Malisan F, Condò I, Testi R. Drug Repositioning in Friedreich Ataxia. Front Neurosci 2022; 16:814445. [PMID: 35221903 PMCID: PMC8863941 DOI: 10.3389/fnins.2022.814445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/07/2022] [Indexed: 12/14/2022] Open
Abstract
Friedreich ataxia is a rare neurodegenerative disorder caused by insufficient levels of the essential mitochondrial protein frataxin. It is a severely debilitating disease that significantly impacts the quality of life of affected patients and reduces their life expectancy, however, an adequate cure is not yet available for patients. Frataxin function, although not thoroughly elucidated, is associated with assembly of iron-sulfur cluster and iron metabolism, therefore insufficient frataxin levels lead to reduced activity of many mitochondrial enzymes involved in the electron transport chain, impaired mitochondrial metabolism, reduced ATP production and inefficient anti-oxidant response. As a consequence, neurons progressively die and patients progressively lose their ability to coordinate movement and perform daily activities. Therapeutic strategies aim at restoring sufficient frataxin levels or at correcting some of the downstream consequences of frataxin deficiency. However, the classical pathways of drug discovery are challenging, require a significant amount of resources and time to reach the final approval, and present a high failure rate. Drug repositioning represents a viable alternative to boost the identification of a therapy, particularly for rare diseases where resources are often limited. In this review we will describe recent efforts aimed at the identification of a therapy for Friedreich ataxia through drug repositioning, and discuss the limitation of such strategies.
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Affiliation(s)
- Alessandra Rufini
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
- Fratagene Therapeutics, Rome, Italy
- Saint Camillus International University of Health and Medical Sciences, Rome, Italy
- *Correspondence: Alessandra Rufini,
| | - Florence Malisan
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
| | - Ivano Condò
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
- Fratagene Therapeutics, Rome, Italy
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8
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Fu X, Eggert M, Yoo S, Patel N, Zhong J, Steinke I, Govindarajulu M, Turumtay EA, Mouli S, Panizzi P, Beyers R, Denney T, Arnold R, Amin RH. The Cardioprotective Mechanism of Phenylaminoethyl Selenides (PAESe) Against Doxorubicin-Induced Cardiotoxicity Involves Frataxin. Front Pharmacol 2021; 11:574656. [PMID: 33912028 PMCID: PMC8072348 DOI: 10.3389/fphar.2020.574656] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/09/2020] [Indexed: 11/28/2022] Open
Abstract
Doxorubicin (DOX) is an anthracycline cancer chemotherapeutic that exhibits cumulative dose-limiting cardiotoxicity and limits its clinical utility. DOX treatment results in the development of morbid cardiac hypertrophy that progresses to congestive heart failure and death. Recent evidence suggests that during the development of DOX mediated cardiac hypertrophy, mitochondrial energetics are severely compromised, thus priming the cardiomyocyte for failure. To mitigate cumulative dose (5 mg/kg, QIW x 4 weeks with 2 weeks recovery) dependent DOX, mediated cardiac hypertrophy, we applied an orally active selenium based compound termed phenylaminoethyl selenides (PAESe) (QIW 10 mg/kg x 5) to our animal model and observed that PAESe attenuates DOX-mediated cardiac hypertrophy in athymic mice, as observed by MRI analysis. Mechanistically, we demonstrated that DOX impedes the stability of the iron-sulfur cluster biogenesis protein Frataxin (FXN) (0.5 fold), resulting in enhanced mitochondrial free iron accumulation (2.5 fold) and reduced aconitase activity (0.4 fold). Our findings further indicate that PAESe prevented the reduction of FXN levels and the ensuing elevation of mitochondrial free iron levels. PAESe has been shown to have anti-oxidative properties in part, by regeneration of glutathione levels. Therefore, we observed that PAESe can mitigate DOX mediated cardiac hypertrophy by enhancing glutathione activity (0.4 fold) and inhibiting ROS formation (1.8 fold). Lastly, we observed that DOX significantly reduced cellular respiration (basal (5%) and uncoupled (10%)) in H9C2 cardiomyoblasts and that PAESe protects against the DOX-mediated attenuation of cellular respiration. In conclusion, the current study determined the protective mechanism of PAESe against DOX mediated myocardial damage and that FXN is implicitly involved in DOX-mediated cardiotoxicity.
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Affiliation(s)
- Xiaoyu Fu
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Mathew Eggert
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Sieun Yoo
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Nikhil Patel
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Juming Zhong
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Ian Steinke
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Manoj Govindarajulu
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | | | - Shravanthi Mouli
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Peter Panizzi
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Ronald Beyers
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, United States.,Auburn University M.R.I. Research Center, Auburn, AL, United States
| | - Thomas Denney
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, United States.,Auburn University M.R.I. Research Center, Auburn, AL, United States
| | - Robert Arnold
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
| | - Rajesh H Amin
- Department of Drug, Discovery and Development, Harrison School of Pharmacy, Auburn University, Alabama, AL, United States
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9
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Castro IH, Bringas M, Doni D, Noguera ME, Capece L, Aran M, Blaustein M, Costantini P, Santos J. Relationship between activity and stability: Design and characterization of stable variants of human frataxin. Arch Biochem Biophys 2020; 691:108491. [PMID: 32707090 DOI: 10.1016/j.abb.2020.108491] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/26/2020] [Accepted: 07/08/2020] [Indexed: 11/16/2022]
Abstract
The relationships between conformational dynamics, stability and protein function are not obvious. Frataxin (FXN) is an essential protein that forms part of a supercomplex dedicated to the iron-sulfur (Fe-S) cluster assembly within the mitochondrial matrix. In humans, the loss of FXN expression or a decrease in its functionality results in Friedreich's Ataxia, a cardio-neurodegenerative disease. Recently, the way in which FXN interacts with the rest of the subunits of the supercomplex was uncovered. This opens a window to explore relationships between structural dynamics and function. In this study, we prepared a set of FXN variants spanning a broad range of conformational stabilities. Variants S160I, S160M and A204R were more stable than the wild-type and showed similar biological activity. Additionally, we prepared SILCAR, a variant that combines S160I, L203C and A204R mutations. SILCAR was 2.4 kcal mol-1 more stable and equally active. Some of the variants were significantly more resistant to proteolysis than the wild-type FXN. SILCAR showed the highest resistance, suggesting a more rigid structure. It was corroborated by means of molecular dynamics simulations. Relaxation dispersion NMR experiments comparing SILCAR and wild-type variants suggested similar internal motions in the microsecond to millisecond timescale. Instead, variant S157I showed higher denaturation resistance but a significant lower function, similarly to that observed for the FRDA variant N146K. We concluded that the contribution of particular side chains to the conformational stability of FXN might be highly subordinated to their impact on both the protein function and the stability of the functional supercomplex.
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Affiliation(s)
- Ignacio Hugo Castro
- Instituto de Biociencias, Biotecnología y Biología Traslacional (iB(3)). Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Buenos Aires, Argentina
| | - Mauro Bringas
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE CONICET), C1428EGA, Buenos Aires, Argentina
| | - Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy
| | - Martin Ezequiel Noguera
- Instituto de Biociencias, Biotecnología y Biología Traslacional (iB(3)). Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Buenos Aires, Argentina; Instituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET, Junín 956, C1113AAD, Buenos Aires, Argentina
| | - Luciana Capece
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE CONICET), C1428EGA, Buenos Aires, Argentina
| | - Martín Aran
- Fundación Instituto Leloir, IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Matías Blaustein
- Instituto de Biociencias, Biotecnología y Biología Traslacional (iB(3)). Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Rivadavia 1917, C1033AAJ, Buenos Aires, Argentina
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy
| | - Javier Santos
- Instituto de Biociencias, Biotecnología y Biología Traslacional (iB(3)). Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Rivadavia 1917, C1033AAJ, Buenos Aires, Argentina; Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Buenos Aires, Argentina.
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10
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Pérez-Luz S, Loria F, Katsu-Jiménez Y, Oberdoerfer D, Yang OL, Lim F, Muñoz-Blanco JL, Díaz-Nido J. Altered Secretome and ROS Production in Olfactory Mucosa Stem Cells Derived from Friedreich's Ataxia Patients. Int J Mol Sci 2020; 21:ijms21186662. [PMID: 32933002 PMCID: PMC7555998 DOI: 10.3390/ijms21186662] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 09/08/2020] [Indexed: 12/14/2022] Open
Abstract
Friedreich’s ataxia is the most common hereditary ataxia for which there is no cure or approved treatment at present. However, therapeutic developments based on the understanding of pathological mechanisms underlying the disease have advanced considerably, with the implementation of cellular models that mimic the disease playing a crucial role. Human olfactory ecto-mesenchymal stem cells represent a novel model that could prove useful due to their accessibility and neurogenic capacity. Here, we isolated and cultured these stem cells from Friedreich´s ataxia patients and healthy donors, characterizing their phenotype and describing disease-specific features such as reduced cell viability, impaired aconitase activity, increased ROS production and the release of cytokines involved in neuroinflammation. Importantly, we observed a positive effect on patient-derived cells, when frataxin levels were restored, confirming the utility of this in vitro model to study the disease. This model will improve our understanding of Friedreich´s ataxia pathogenesis and will help in developing rationally designed therapeutic strategies.
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Affiliation(s)
- Sara Pérez-Luz
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain; (S.P.-L.); (D.O.); (O.-L.Y.); (J.D.-N.)
- Molecular Genetics Unit, Institute of Rare Diseases Research, Institute of Health Carlos III (ISCIII), Ctra. Majadahonda-Pozuelo Km 2,200, 28220 Madrid, Spain
| | - Frida Loria
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain; (S.P.-L.); (D.O.); (O.-L.Y.); (J.D.-N.)
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, Calle Budapest 1, 28922 Madrid, Spain
- Correspondence: ; Tel.: +34-911-964-594
| | - Yurika Katsu-Jiménez
- Karolinska Institutet, Department of Microbiology Tumor and Cell Biology, Solnaväjen 1, 171 77 Stockholm, Sweden;
| | - Daniel Oberdoerfer
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain; (S.P.-L.); (D.O.); (O.-L.Y.); (J.D.-N.)
| | - Oscar-Li Yang
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain; (S.P.-L.); (D.O.); (O.-L.Y.); (J.D.-N.)
| | - Filip Lim
- Department of Molecular Biology, Autonomous University of Madrid, Francisco Tomás y Valiente 7, 28049 Madrid, Spain;
| | - José Luis Muñoz-Blanco
- Department of Neurology, Hospital Universitario Gregorio Marañón, Dr. Esquerdo 46, 28007 Madrid, Spain;
| | - Javier Díaz-Nido
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain; (S.P.-L.); (D.O.); (O.-L.Y.); (J.D.-N.)
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11
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The Ubiquitin Proteasome System in Neuromuscular Disorders: Moving Beyond Movement. Int J Mol Sci 2020; 21:ijms21176429. [PMID: 32899400 PMCID: PMC7503226 DOI: 10.3390/ijms21176429] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/30/2020] [Accepted: 08/31/2020] [Indexed: 12/12/2022] Open
Abstract
Neuromuscular disorders (NMDs) affect 1 in 3000 people worldwide. There are more than 150 different types of NMDs, where the common feature is the loss of muscle strength. These disorders are classified according to their neuroanatomical location, as motor neuron diseases, peripheral nerve diseases, neuromuscular junction diseases, and muscle diseases. Over the years, numerous studies have pointed to protein homeostasis as a crucial factor in the development of these fatal diseases. The ubiquitin-proteasome system (UPS) plays a fundamental role in maintaining protein homeostasis, being involved in protein degradation, among other cellular functions. Through a cascade of enzymatic reactions, proteins are ubiquitinated, tagged, and translocated to the proteasome to be degraded. Within the ubiquitin system, we can find three main groups of enzymes: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-conjugating enzymes), and E3 (ubiquitin-protein ligases). Only the ubiquitinated proteins with specific chain linkages (such as K48) will be degraded by the UPS. In this review, we describe the relevance of this system in NMDs, summarizing the UPS proteins that have been involved in pathological conditions and neuromuscular disorders, such as Spinal Muscular Atrophy (SMA), Charcot-Marie-Tooth disease (CMT), or Duchenne Muscular Dystrophy (DMD), among others. A better knowledge of the processes involved in the maintenance of proteostasis may pave the way for future progress in neuromuscular disorder studies and treatments.
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12
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Bon C, Luffarelli R, Russo R, Fortuni S, Pierattini B, Santulli C, Fimiani C, Persichetti F, Cotella D, Mallamaci A, Santoro C, Carninci P, Espinoza S, Testi R, Zucchelli S, Condò I, Gustincich S. SINEUP non-coding RNAs rescue defective frataxin expression and activity in a cellular model of Friedreich's Ataxia. Nucleic Acids Res 2019; 47:10728-10743. [PMID: 31584077 PMCID: PMC6847766 DOI: 10.1093/nar/gkz798] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/08/2019] [Accepted: 09/28/2019] [Indexed: 12/16/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an untreatable disorder with neuro- and cardio-degenerative progression. This monogenic disease is caused by the hyper-expansion of naturally occurring GAA repeats in the first intron of the FXN gene, encoding for frataxin, a protein implicated in the biogenesis of iron-sulfur clusters. As the genetic defect interferes with FXN transcription, FRDA patients express a normal frataxin protein but at insufficient levels. Thus, current therapeutic strategies are mostly aimed to restore physiological FXN expression. We have previously described SINEUPs, natural and synthetic antisense long non-coding RNAs, which promote translation of partially overlapping mRNAs through the activity of an embedded SINEB2 domain. Here, by in vitro screening, we have identified a number of SINEUPs targeting human FXN mRNA and capable to up-regulate frataxin protein to physiological amounts acting at the post-transcriptional level. Furthermore, FXN-specific SINEUPs promote the recovery of disease-associated mitochondrial aconitase defects in FRDA-derived cells. In summary, we provide evidence that SINEUPs may be the first gene-specific therapeutic approach to activate FXN translation in FRDA and, more broadly, a novel scalable platform to develop new RNA-based therapies for haploinsufficient diseases.
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Affiliation(s)
- Carlotta Bon
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Riccardo Luffarelli
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Roberta Russo
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Silvia Fortuni
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Bianca Pierattini
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Chiara Santulli
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Cristina Fimiani
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Francesca Persichetti
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Diego Cotella
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Antonello Mallamaci
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Claudio Santoro
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Piero Carninci
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, Japan
| | - Stefano Espinoza
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Silvia Zucchelli
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Ivano Condò
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Stefano Gustincich
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
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13
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Gottesfeld JM. Molecular Mechanisms and Therapeutics for the GAA·TTC Expansion Disease Friedreich Ataxia. Neurotherapeutics 2019; 16:1032-1049. [PMID: 31317428 PMCID: PMC6985418 DOI: 10.1007/s13311-019-00764-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Friedreich ataxia (FRDA), the most common inherited ataxia, is caused by transcriptional silencing of the nuclear FXN gene, encoding the essential mitochondrial protein frataxin. Currently, there is no approved therapy for this fatal disorder. Gene silencing in FRDA is due to hyperexpansion of the triplet repeat sequence GAA·TTC in the first intron of the FXN gene, which results in chromatin histone modifications consistent with heterochromatin formation. Frataxin is involved in mitochondrial iron homeostasis and the assembly and transfer of iron-sulfur clusters to various mitochondrial enzymes and components of the electron transport chain. Frataxin insufficiency leads to progressive spinocerebellar neurodegeneration, causing symptoms of gait and limb ataxia, slurred speech, muscle weakness, sensory loss, and cardiomyopathy in many patients, resulting in death in early adulthood. Numerous approaches are being taken to find a treatment for FRDA, including excision or correction of the repeats by genome engineering methods, gene activation with small molecules or artificial transcription factors, delivery of frataxin to affected cells by protein replacement therapy, gene therapy, or small molecules to increase frataxin protein levels, and therapies aimed at countering the cellular consequences of reduced frataxin. This review will summarize the mechanisms involved in repeat-mediated gene silencing and recent efforts aimed at development of therapeutics.
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Affiliation(s)
- Joel M Gottesfeld
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, 92037, USA.
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14
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Alfedi G, Luffarelli R, Condò I, Pedini G, Mannucci L, Massaro DS, Benini M, Toschi N, Alaimo G, Panarello L, Pacini L, Fortuni S, Serio D, Malisan F, Testi R, Rufini A. Drug repositioning screening identifies etravirine as a potential therapeutic for friedreich's ataxia. Mov Disord 2019; 34:323-334. [PMID: 30624801 DOI: 10.1002/mds.27604] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/31/2018] [Accepted: 11/05/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Friedreich's ataxia is an autosomal-recessive cerebellar ataxia caused by mutation of the frataxin gene, resulting in decreased frataxin expression, mitochondrial dysfunction, and oxidative stress. Currently, no treatment is available for Friedreich's ataxia patients. Given that levels of residual frataxin critically affect disease severity, the main goal of a specific therapy for Friedreich's ataxia is to increase frataxin levels. OBJECTIVES With the aim to accelerate the development of a new therapy for Friedreich's ataxia, we took a drug repositioning approach to identify market-available drugs able to increase frataxin levels. METHODS Using a cell-based reporter assay to monitor variation in frataxin amount, we performed a high-throughput screening of a library containing 853 U.S. Food and Drug Administration-approved drugs. RESULTS Among the potentially interesting candidates isolated from the screening, we focused our attention on etravirine, an antiviral drug currently in use as an anti-human immunodeficiency virus therapy. Here, we show that etravirine can promote a significant increase in frataxin levels in cells derived from Friedreich's ataxia patients, by enhancing frataxin messenger RNA translation. Importantly, frataxin accumulation in treated patient cell lines is comparable to frataxin levels in unaffected carrier cells, suggesting that etravirine could be therapeutically relevant. Indeed, etravirine treatment restores the activity of the iron-sulphur cluster containing enzyme aconitase and confers resistance to oxidative stress in cells derived from Friedreich's ataxia patients. CONCLUSIONS Considering its excellent safety profile along with its ability to increase frataxin levels and correct some of the disease-related defects, etravirine represents a promising candidate as a therapeutic for Friedreich's ataxia. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Giulia Alfedi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Riccardo Luffarelli
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Giorgia Pedini
- Laboratory of Molecular Neurobiology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Liliana Mannucci
- Laboratory of Molecular Neurobiology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Damiano S Massaro
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Monica Benini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
| | - Nicola Toschi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging and Harvard Medical School, Boston, Massachusetts, USA
| | - Giorgia Alaimo
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
| | - Luca Panarello
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Laura Pacini
- Laboratory of Molecular Neurobiology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
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15
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Lai JI, Nachun D, Petrosyan L, Throesch B, Campau E, Gao F, Baldwin KK, Coppola G, Gottesfeld JM, Soragni E. Transcriptional profiling of isogenic Friedreich ataxia neurons and effect of an HDAC inhibitor on disease signatures. J Biol Chem 2019; 294:1846-1859. [PMID: 30552117 PMCID: PMC6369281 DOI: 10.1074/jbc.ra118.006515] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/12/2018] [Indexed: 12/16/2022] Open
Abstract
Friedreich ataxia (FRDA) is a neurodegenerative disorder caused by transcriptional silencing of the frataxin (FXN) gene, resulting in loss of the essential mitochondrial protein frataxin. Based on the knowledge that a GAA·TTC repeat expansion in the first intron of FXN induces heterochromatin, we previously showed that 2-aminobenzamide-type histone deacetylase inhibitors (HDACi) increase FXN mRNA levels in induced pluripotent stem cell (iPSC)-derived FRDA neurons and in circulating lymphocytes from patients after HDACi oral administration. How the reduced expression of frataxin leads to neurological and other systemic symptoms in FRDA patients remains unclear. Similar to other triplet-repeat disorders, it is unknown why FRDA affects only specific cell types, primarily the large sensory neurons of the dorsal root ganglia and cardiomyocytes. The combination of iPSC technology and genome-editing techniques offers the unique possibility to address these questions in a relevant cell model of FRDA, obviating confounding effects of variable genetic backgrounds. Here, using "scarless" gene-editing methods, we created isogenic iPSC lines that differ only in the length of the GAA·TTC repeats. To uncover the gene expression signatures due to the GAA·TTC repeat expansion in FRDA neuronal cells and the effect of HDACi on these changes, we performed RNA-seq-based transcriptomic analysis of iPSC-derived central nervous system (CNS) and isogenic sensory neurons. We found that cellular pathways related to neuronal function, regulation of transcription, extracellular matrix organization, and apoptosis are affected by frataxin loss in neurons of the CNS and peripheral nervous system and that these changes are partially restored by HDACi treatment.
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Affiliation(s)
- Jiun-I Lai
- From the Departments of Molecular Medicine and
| | - Daniel Nachun
- the Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, California 90095
| | | | - Benjamin Throesch
- Neuroscience, The Scripps Research Institute, La Jolla, California 92037 and
| | | | - Fuying Gao
- the Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, California 90095
| | - Kristin K Baldwin
- Neuroscience, The Scripps Research Institute, La Jolla, California 92037 and
| | - Giovanni Coppola
- the Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, California 90095
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16
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Castro IH, Pignataro MF, Sewell KE, Espeche LD, Herrera MG, Noguera ME, Dain L, Nadra AD, Aran M, Smal C, Gallo M, Santos J. Frataxin Structure and Function. Subcell Biochem 2019; 93:393-438. [PMID: 31939159 DOI: 10.1007/978-3-030-28151-9_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mammalian frataxin is a small mitochondrial protein involved in iron sulfur cluster assembly. Frataxin deficiency causes the neurodegenerative disease Friedreich's Ataxia. Valuable knowledge has been gained on the structural dynamics of frataxin, metal-ion-protein interactions, as well as on the effect of mutations on protein conformation, stability and internal motions. Additionally, laborious studies concerning the enzymatic reactions involved have allowed for understanding the capability of frataxin to modulate Fe-S cluster assembly function. Remarkably, frataxin biological function depends on its interaction with some proteins to form a supercomplex, among them NFS1 desulfurase and ISCU, the scaffolding protein. By combining multiple experimental tools including high resolution techniques like NMR and X-ray, but also SAXS, crosslinking and mass-spectrometry, it was possible to build a reliable model of the structure of the desulfurase supercomplex NFS1/ACP-ISD11/ISCU/frataxin. In this chapter, we explore these issues showing how the scientific view concerning frataxin structure-function relationships has evolved over the last years.
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Affiliation(s)
- Ignacio Hugo Castro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - María Florencia Pignataro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - Karl Ellioth Sewell
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - Lucía Daniela Espeche
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - María Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, B1876BXD, Bernal, Provincia de Buenos Aires, Argentina
| | - Liliana Dain
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - Alejandro Daniel Nadra
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Martín Aran
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Clara Smal
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Mariana Gallo
- IRBM Science Park S.p.A, Via Pontina km 30,600, 00071, Pomezia, RM, Italy
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina.
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina.
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17
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Zeitlberger AM, Thomas-Black G, Garcia-Moreno H, Foiani M, Heslegrave AJ, Zetterberg H, Giunti P. Plasma Markers of Neurodegeneration Are Raised in Friedreich's Ataxia. Front Cell Neurosci 2018; 12:366. [PMID: 30425621 PMCID: PMC6218876 DOI: 10.3389/fncel.2018.00366] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 09/27/2018] [Indexed: 12/13/2022] Open
Abstract
Background: Friedreich's ataxia (FRDA) is the most common autosomal recessive ataxia. Disease-modifying treatments are not available yet; however, several compounds are currently under investigation. As a result, there is a growing need for the identification of robust and easily accessible biomarkers for the monitoring of disease activity and therapeutic efficacy. The simultaneous measurement of multiple brain-derived proteins could represent a time- and cost-efficient approach for biomarker investigation in pathologically complex neurodegenerative diseases like FRDA. Objectives: To investigate the role of plasma neurofilament-light chain (NfL), glial fibrillary acidic protein (GFAP), total tau (t-tau) and ubiquitin C-terminal hydrolase L1(UCHL1) as biomarkers in FRDA. Additionally, NfL measurements derived from the novel multiplex assay were compared to those from an established NfL singleplex assay. Methods: In this study, an ultrasensitive Single molecule array (Simoa) 4-plex assay was used for the measurement of plasma NfL, GFAP, t-tau, and UCHL1 in 33 FRDA patients and 13 age-matched controls. Differences in biomarker concentrations between these groups were computed and associations with genetic and disease related parameters investigated. Additionally, the agreement between NfL measurements derived from the 4-Plex and an established Simoa NfL singleplex assay was assessed. Results: Mean plasma NfL, GFAP and UCHL1 levels were significantly higher in FRDA patients than in controls (NfL: p < 0.001; GFAP: p = 0.006, and UCHL1: p = 0.020). Conversely, there was no significant difference in concentrations of t-tau in the patient and control group (p = 0.236). None of the proteins correlated with the GAA repeat length or the employed measures of disease severity. The individual NfL values derived from the two assays showed a strong concordance (rc = 0.93). Although the mean difference of 1.29 pg/mL differed significantly from 0 (p = 0.006), regression analysis did not indicate the presence of a proportional bias. Conclusion: This is the first study demonstrating that NfL, GFAP, and UCHL1 levels are raised in FRDA, potentially reflecting ongoing neuronal degeneration and glial activation. Further studies are required to determine their role as marker for disease activity and progression. Furthermore, the novel 4-plex assay appears to be a valid tool to simultaneously measure brain-derived proteins at extremely low concentrations in the peripheral circulation.
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Affiliation(s)
- Anna M Zeitlberger
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, University College London Hospitals Foundation NHS Trust, London, United Kingdom
| | - Gilbert Thomas-Black
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, University College London Hospitals Foundation NHS Trust, London, United Kingdom
| | - Hector Garcia-Moreno
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, University College London Hospitals Foundation NHS Trust, London, United Kingdom
| | - Martha Foiani
- UK Dementia Research Institute, University College London, London, United Kingdom.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Amanda J Heslegrave
- UK Dementia Research Institute, University College London, London, United Kingdom.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Henrik Zetterberg
- UK Dementia Research Institute, University College London, London, United Kingdom.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.,Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.,Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, University College London Hospitals Foundation NHS Trust, London, United Kingdom
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18
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Makhouri FR, Ghasemi JB. In Silico Studies in Drug Research Against Neurodegenerative Diseases. Curr Neuropharmacol 2018; 16:664-725. [PMID: 28831921 PMCID: PMC6080098 DOI: 10.2174/1570159x15666170823095628] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 07/24/2017] [Accepted: 08/16/2017] [Indexed: 01/14/2023] Open
Abstract
Background Neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis, Parkinson's disease (PD), spinal cerebellar ataxias, and spinal and bulbar muscular atrophy are described by slow and selective degeneration of neurons and axons in the central nervous system (CNS) and constitute one of the major challenges of modern medicine. Computer-aided or in silico drug design methods have matured into powerful tools for reducing the number of ligands that should be screened in experimental assays. Methods In the present review, the authors provide a basic background about neurodegenerative diseases and in silico techniques in the drug research. Furthermore, they review the various in silico studies reported against various targets in neurodegenerative diseases, including homology modeling, molecular docking, virtual high-throughput screening, quantitative structure activity relationship (QSAR), hologram quantitative structure activity relationship (HQSAR), 3D pharmacophore mapping, proteochemometrics modeling (PCM), fingerprints, fragment-based drug discovery, Monte Carlo simulation, molecular dynamic (MD) simulation, quantum-mechanical methods for drug design, support vector machines, and machine learning approaches. Results Detailed analysis of the recently reported case studies revealed that the majority of them use a sequential combination of ligand and structure-based virtual screening techniques, with particular focus on pharmacophore models and the docking approach. Conclusion Neurodegenerative diseases have a multifactorial pathoetiological origin, so scientists have become persuaded that a multi-target therapeutic strategy aimed at the simultaneous targeting of multiple proteins (and therefore etiologies) involved in the development of a disease is recommended in future.
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Affiliation(s)
| | - Jahan B Ghasemi
- Chemistry Department, Faculty of Sciences, University of Tehran, Tehran, Iran
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19
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Khdour OM, Bandyopadhyay I, Chowdhury SR, Visavadiya NP, Hecht SM. Lipophilic methylene blue analogues enhance mitochondrial function and increase frataxin levels in a cellular model of Friedreich's ataxia. Bioorg Med Chem 2018; 26:3359-3369. [PMID: 29773347 DOI: 10.1016/j.bmc.2018.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 04/25/2018] [Accepted: 05/03/2018] [Indexed: 01/31/2023]
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder resulting from reduced expression of the protein frataxin (FXN). Although its function is not fully understood, frataxin appears to help assemble iron sulfur clusters; these are critical for the function of many proteins, including those needed for mitochondrial energy production. Finding ways to increase FXN levels has been a major therapeutic strategy for this disease. Previously, we described a novel series of methylene violet analogues and their structural optimization as potential therapeutic agents for neurodegenerative and mitochondrial disorders. Presently, a series of methylene blue analogues has been synthesized and characterized for their in vitro biochemical and biological properties in cultured Friedreich's ataxia lymphocytes. Favorable methylene blue analogues were shown to increase frataxin levels and mitochondrial biogenesis, and to improve aconitase activity. The analogues were found to be good ROS scavengers, and able to protect cultured FRDA lymphocytes from oxidative stress resulting from inhibition of complex I and from glutathione depletion. The analogues also preserved mitochondrial membrane potential and augmented ATP production. Our results suggest that analogue 5, emerging from the initial structure of the parent compound methylene blue (MB), represents a promising lead structure and lacks the cytotoxicity associated with the parent compound MB.
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Affiliation(s)
- Omar M Khdour
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
| | - Indrajit Bandyopadhyay
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Sandipan Roy Chowdhury
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Nishant P Visavadiya
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Sidney M Hecht
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
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20
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Vannocci T, Notario Manzano R, Beccalli O, Bettegazzi B, Grohovaz F, Cinque G, de Riso A, Quaroni L, Codazzi F, Pastore A. Adding a temporal dimension to the study of Friedreich's ataxia: the effect of frataxin overexpression in a human cell model. Dis Model Mech 2018; 11:dmm032706. [PMID: 29794127 PMCID: PMC6031361 DOI: 10.1242/dmm.032706] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/08/2018] [Indexed: 12/27/2022] Open
Abstract
The neurodegenerative disease Friedreich's ataxia is caused by lower than normal levels of frataxin, an important protein involved in iron-sulfur (Fe-S) cluster biogenesis. An important step in designing strategies to treat this disease is to understand whether increasing the frataxin levels by gene therapy would simply be beneficial or detrimental, because previous studies, mostly based on animal models, have reported conflicting results. Here, we have exploited an inducible model, which we developed using the CRISPR/Cas9 methodology, to study the effects of frataxin overexpression in human cells and monitor how the system recovers after overexpression. Using new tools, which range from high-throughput microscopy to in cell infrared, we prove that overexpression of the frataxin gene affects the cellular metabolism. It also leads to a significant increase of oxidative stress and labile iron pool levels. These cellular alterations are similar to those observed when the gene is partly silenced, as occurs in Friedreich's ataxia patients. Our data suggest that the levels of frataxin must be tightly regulated and fine-tuned, with any imbalance leading to oxidative stress and toxicity.
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Affiliation(s)
- Tommaso Vannocci
- Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London, 5 Cutcombe Road, London SE5 9RT, UK
| | - Roberto Notario Manzano
- Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London, 5 Cutcombe Road, London SE5 9RT, UK
| | - Ombretta Beccalli
- Division of Neuroscience, Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Barbara Bettegazzi
- Division of Neuroscience, Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Fabio Grohovaz
- Division of Neuroscience, Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Gianfelice Cinque
- Department of Physical Chemistry and Electrochemistry, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | | | - Luca Quaroni
- Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, PL-30387, Kraków, Poland
| | - Franca Codazzi
- Division of Neuroscience, Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Annalisa Pastore
- Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London, 5 Cutcombe Road, London SE5 9RT, UK
- Molecular Medicine Department, University of Pavia, I-27100 Pavia, Italy
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21
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Cherif K, Gérard C, Rousseau J, Ouellet DL, Chapdelaine P, Tremblay JP. Increased Frataxin Expression Induced in Friedreich Ataxia Cells by Platinum TALE-VP64s or Platinum TALE-SunTag. MOLECULAR THERAPY-NUCLEIC ACIDS 2018; 12:19-32. [PMID: 30195758 PMCID: PMC6019861 DOI: 10.1016/j.omtn.2018.04.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 11/28/2022]
Abstract
Frataxin gene (FXN) expression is reduced in Friedreich’s ataxia patients due to an increase in the number of GAA trinucleotides in intron 1. The frataxin protein, encoded by that gene, plays an important role in mitochondria’s iron metabolism. Platinum TALE (plTALE) proteins targeting the regulatory region of the FXN gene, fused with a transcriptional activator (TA) such as VP64 or P300, were used to increase the expression of that gene. Many effectors, plTALEVP64, plTALEp300, and plTALESunTag, targeting 14 sequences of the FXN gene promoter or intron 1 were produced. This permitted selection of 3 plTALEVP64s and 2 plTALESunTag that increased FXN gene expression by up to 19-fold in different Friedreich ataxia (FRDA) primary fibroblasts. Adeno-associated viruses were used to deliver the best effectors to the YG8R mouse model to validate their efficiencies in vivo. Our results showed that these selected plTALEVP64s or plTALESunTag induced transcriptional activity of the endogenous FXN gene as well as expression of the frataxin protein in YG8R mouse heart by 10-fold and in skeletal muscles by up to 35-fold. The aconitase activity was positively modulated by the frataxin level in mitochondria, and it was, thus, increased in vitro and in vivo by the increased frataxin expression.
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Affiliation(s)
- Khadija Cherif
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Catherine Gérard
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Joël Rousseau
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Dominique L Ouellet
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Pierre Chapdelaine
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Jacques P Tremblay
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada.
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22
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Progress in the treatment of Friedreich ataxia. Neurol Neurochir Pol 2018; 52:129-139. [PMID: 29499876 DOI: 10.1016/j.pjnns.2018.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 02/12/2018] [Indexed: 11/19/2022]
Abstract
Friedreich ataxia (FRDA) is a progressive neurological disorder affecting approximately 1 in 29,000 individuals of European descent. At present, there is no approved pharmacological treatment for this condition however research into treatment of FRDA has advanced considerably over the last two decades since the genetic cause was identified. Current proposed treatment strategies include decreasing oxidative stress, increasing cellular frataxin, improving mitochondrial function as well as modulating frataxin controlled metabolic pathways. Genetic and cell based therapies also hold great promise. Finally, physical therapies are being explored as a means of maximising function in those affected by FRDA.
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23
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Chandran V, Gao K, Swarup V, Versano R, Dong H, Jordan MC, Geschwind DH. Inducible and reversible phenotypes in a novel mouse model of Friedreich's Ataxia. eLife 2017; 6:e30054. [PMID: 29257745 PMCID: PMC5736353 DOI: 10.7554/elife.30054] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/20/2017] [Indexed: 12/13/2022] Open
Abstract
Friedreich's ataxia (FRDA), the most common inherited ataxia, is caused by recessive mutations that reduce the levels of frataxin (FXN), a mitochondrial iron binding protein. We developed an inducible mouse model of Fxn deficiency that enabled us to control the onset and progression of disease phenotypes by the modulation of Fxn levels. Systemic knockdown of Fxn in adult mice led to multiple phenotypes paralleling those observed in human patients across multiple organ systems. By reversing knockdown after clinical features appear, we were able to determine to what extent observed phenotypes represent reversible cellular dysfunction. Remarkably, upon restoration of near wild-type FXN levels, we observed significant recovery of function, associated pathology and transcriptomic dysregulation even after substantial motor dysfunction and pathology were observed. This model will be of broad utility in therapeutic development and in refining our understanding of the relative contribution of reversible cellular dysfunction at different stages in disease.
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Affiliation(s)
- Vijayendran Chandran
- Program in Neurogenetics, Department of Neurology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Kun Gao
- Program in Neurogenetics, Department of Neurology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Vivek Swarup
- Program in Neurogenetics, Department of Neurology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Revital Versano
- Program in Neurogenetics, Department of Neurology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Hongmei Dong
- Program in Neurogenetics, Department of Neurology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Maria C Jordan
- Department of Physiology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
| | - Daniel H Geschwind
- Program in Neurogenetics, Department of Neurology, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
- Department of Human Genetics, David Geffen School of MedicineUniversity of California, Los AngelesLos AngelesUnited States
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24
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Edenharter O, Clement J, Schneuwly S, Navarro JA. Overexpression of Drosophila frataxin triggers cell death in an iron-dependent manner. J Neurogenet 2017; 31:189-202. [PMID: 28838288 DOI: 10.1080/01677063.2017.1363200] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/31/2017] [Indexed: 10/24/2022]
Abstract
Friedreich ataxia (FRDA) is the most important autosomal recessive ataxia in the Caucasian population. FRDA patients display severe neurological and cardiac symptoms that reflect a strong cellular and axonal degeneration. FRDA is caused by a loss of function of the mitochondrial protein frataxin which impairs the biosynthesis of iron-sulfur clusters and in turn the catalytic activity of several enzymes in the Krebs cycle and the respiratory chain leading to a diminished energy production. Although FRDA is due to frataxin depletion, overexpression might also be very helpful to better understand cellular functions of frataxin. In this work, we have increased frataxin expression in neurons to elucidate specific roles that frataxin might play in these tissues. Using molecular, biochemical, histological and behavioral methods, we report that frataxin overexpression is sufficient to increase oxidative phosphorylation, modify mitochondrial morphology, alter iron homeostasis and trigger oxidative stress-dependent cell death. Interestingly, genetic manipulation of mitochondrial iron metabolism by silencing mitoferrin successfully improves cell survival under oxidative-attack conditions, although enhancing antioxidant defenses or mitochondrial fusion failed to ameliorate frataxin overexpression phenotypes. This result suggests that cell degeneration is directly related to enhanced incorporation of iron into the mitochondria. Drosophila frataxin overexpression might also provide an alternative approach to identify processes that are important in FRDA such as changes in mitochondrial morphology and oxidative stress induced cell death.
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Affiliation(s)
- Oliver Edenharter
- a Institute of Zoology , University of Regensburg , Regensburg , Germany
| | - Janik Clement
- a Institute of Zoology , University of Regensburg , Regensburg , Germany
| | - Stephan Schneuwly
- a Institute of Zoology , University of Regensburg , Regensburg , Germany
| | - Juan A Navarro
- a Institute of Zoology , University of Regensburg , Regensburg , Germany
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25
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Strawser C, Schadt K, Hauser L, McCormick A, Wells M, Larkindale J, Lin H, Lynch DR. Pharmacological therapeutics in Friedreich ataxia: the present state. Expert Rev Neurother 2017; 17:895-907. [PMID: 28724340 DOI: 10.1080/14737175.2017.1356721] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Friedreich ataxia (FRDA) is a progressive, inherited, neurodegenerative disease for which there is currently no cure or approved treatment. FRDA is caused by deficits in the production and expression of frataxin, a protein found in the mitochondria that is most likely responsible for regulating iron-sulfur cluster enzymes within the cell. A decrease in frataxin causes dysfunction of adenosine triphosphate synthesis, accumulation of mitochondrial iron, and other events leading to downstream cellular dysfunction. Areas covered: Therapeutic development for FRDA currently focuses on improving mitochondrial function and finding ways to increase frataxin expression. Additionally, the authors will review potential approaches aimed at iron modulation and genetic modulation. Finally, gene therapy is progressing rapidly and is being explored as a treatment for FRDA. Expert commentary: The collection of multiple therapeutic approaches provides many possible ways to treat FRDA. Although the mitochondrial approaches are not thought to be curative, as the primary frataxin deficit will remain, they may still produce improvements in quality of life and slowing of progression. Therapies aimed at frataxin restoration are more likely to truly modify the disease, with gene therapy as the best possibility to alter the course of the disease from both a cardiac and neurological perspective.
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Affiliation(s)
| | - Kimberly Schadt
- a Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Lauren Hauser
- a Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | | | - McKenzie Wells
- a Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Jane Larkindale
- a Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Hong Lin
- a Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - David R Lynch
- a Children's Hospital of Philadelphia , Philadelphia , PA , USA
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26
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Bürk K. Friedreich Ataxia: current status and future prospects. CEREBELLUM & ATAXIAS 2017; 4:4. [PMID: 28405347 PMCID: PMC5383992 DOI: 10.1186/s40673-017-0062-x] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/24/2017] [Indexed: 01/23/2023]
Abstract
Friedreich ataxia (FA) represents the most frequent type of inherited ataxia. Most patients carry homozygous GAA expansions in the first intron of the frataxin gene on chromosome 9. Due to epigenetic alterations, frataxin expression is significantly reduced. Frataxin is a mitochondrial protein. Its deficiency leads to mitochondrial iron overload, defective energy supply and generation of reactive oxygen species. This review gives an overview over clinical and genetic aspects of FA and discusses current concepts of frataxin biogenesis and function as well as new therapeutic strategies.
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Affiliation(s)
- Katrin Bürk
- University of Marburg, and Paracelsus-Elena Klinik, Klinikstr. 16, 34128 Kassel, Germany
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27
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Benini M, Fortuni S, Condò I, Alfedi G, Malisan F, Toschi N, Serio D, Massaro DS, Arcuri G, Testi R, Rufini A. E3 Ligase RNF126 Directly Ubiquitinates Frataxin, Promoting Its Degradation: Identification of a Potential Therapeutic Target for Friedreich Ataxia. Cell Rep 2017; 18:2007-2017. [PMID: 28228265 PMCID: PMC5329121 DOI: 10.1016/j.celrep.2017.01.079] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/14/2016] [Accepted: 01/29/2017] [Indexed: 12/21/2022] Open
Abstract
Friedreich ataxia (FRDA) is a severe genetic neurodegenerative disease caused by reduced expression of the mitochondrial protein frataxin. To date, there is no therapy to treat this condition. The amount of residual frataxin critically affects the severity of the disease; thus, attempts to restore physiological frataxin levels are considered therapeutically relevant. Frataxin levels are controlled by the ubiquitin-proteasome system; therefore, inhibition of the frataxin E3 ligase may represent a strategy to achieve an increase in frataxin levels. Here, we report the identification of the RING E3 ligase RNF126 as the enzyme that specifically mediates frataxin ubiquitination and targets it for degradation. RNF126 interacts with frataxin and promotes its ubiquitination in a catalytic activity-dependent manner, both in vivo and in vitro. Most importantly, RNF126 depletion results in frataxin accumulation in cells derived from FRDA patients, highlighting the relevance of RNF126 as a new therapeutic target for Friedreich ataxia.
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Affiliation(s)
- Monica Benini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Giulia Alfedi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Nicola Toschi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging and Harvard Medical School, Boston, MA 02115, USA
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy
| | - Damiano Sergio Massaro
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Gaetano Arcuri
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy.
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28
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Faraj SE, González-Lebrero RM, Roman EA, Santos J. Human Frataxin Folds Via an Intermediate State. Role of the C-Terminal Region. Sci Rep 2016; 6:20782. [PMID: 26856628 PMCID: PMC4746760 DOI: 10.1038/srep20782] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/12/2016] [Indexed: 11/30/2022] Open
Abstract
The aim of this study is to investigate the folding reaction of human frataxin, whose deficiency causes the neurodegenerative disease Friedreich's Ataxia (FRDA). The characterization of different conformational states would provide knowledge about how frataxin can be stabilized without altering its functionality. Wild-type human frataxin and a set of mutants, including two highly destabilized FRDA-associated variants were studied by urea-induced folding/unfolding in a rapid mixing device and followed by circular dichroism. The analysis clearly indicates the existence of an intermediate state (I) in the folding route with significant secondary structure content but relatively low compactness, compared with the native ensemble. However, at high NaCl concentrations I-state gains substantial compaction, and the unfolding barrier is strongly affected, revealing the importance of electrostatics in the folding mechanism. The role of the C-terminal region (CTR), the key determinant of frataxin stability, was also studied. Simulations consistently with experiments revealed that this stretch is essentially unstructured, in the most compact transition state ensemble (TSE2). The complete truncation of the CTR drastically destabilizes the native state without altering TSE2. Results presented here shed light on the folding mechanism of frataxin, opening the possibility of mutating it to generate hyperstable variants without altering their folding kinetics.
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Affiliation(s)
- Santiago E. Faraj
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
| | - Rodolfo M. González-Lebrero
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
| | - Ernesto A. Roman
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
| | - Javier Santos
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
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