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Volianskis R, Lundbye CJ, Petroff GN, Jane DE, Georgiou J, Collingridge GL. Cage effects on synaptic plasticity and its modulation in a mouse model of fragile X syndrome. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230484. [PMID: 38853552 DOI: 10.1098/rstb.2023.0484] [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: 02/01/2024] [Accepted: 04/08/2024] [Indexed: 06/11/2024] Open
Abstract
Fragile X syndrome (FXS) is characterized by impairments in executive function including different types of learning and memory. Long-term potentiation (LTP), thought to underlie the formation of memories, has been studied in the Fmr1 mouse model of FXS. However, there have been many discrepancies in the literature with inconsistent use of littermate and non-littermate Fmr1 knockout (KO) and wild-type (WT) control mice. Here, the influence of the breeding strategy (cage effect) on short-term potentiation (STP), LTP, contextual fear conditioning (CFC), expression of N-methyl-d-aspartate receptor (NMDAR) subunits and the modulation of NMDARs, were examined. The largest deficits in STP, LTP and CFC were found in KO mice compared with non-littermate WT. However, the expression of NMDAR subunits was unchanged in this comparison. Rather, NMDAR subunit (GluN1, 2A, 2B) expression was sensitive to the cage effect, with decreased expression in both WT and KO littermates compared with non-littermates. Interestingly, an NMDAR-positive allosteric modulator, UBP714, was only effective in potentiating the induction of LTP in non-littermate KO mice and not the littermate KO mice. These results suggest that commonly studied phenotypes in Fmr1 KOs are sensitive to the cage effect and therefore the breeding strategy may contribute to discrepancies in the literature.This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Rasa Volianskis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario M5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Camilla J Lundbye
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario M5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Gillian N Petroff
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario M5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - David E Jane
- Hello Bio Limited, Cabot Park, Avonmouth, Bristol BS11 0QL, UK
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario M5G 1X5, Canada
- TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Graham L Collingridge
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario M5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Protic D, Hagerman R. State-of-the-art therapies for fragile X syndrome. Dev Med Child Neurol 2024; 66:863-871. [PMID: 38385885 PMCID: PMC11144093 DOI: 10.1111/dmcn.15885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/23/2024]
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by a full mutation (> 200 CGG repeats) in the FMR1 gene. FXS is the leading cause of inherited intellectual disabilities and the most commonly known genetic cause of autism spectrum disorder. Children with FXS experience behavioral and sleep problems, anxiety, inattention, learning difficulties, and speech and language delays. There are no approved medications for FXS; however, there are several interventions and treatments aimed at managing the symptoms and improving the quality of life of individuals with FXS. A combination of non-pharmacological therapies and pharmacotherapy is currently the most effective treatment for FXS. Currently, several targeted treatments, such as metformin, sertraline, and cannabidiol, can be used by clinicians to treat FXS. Gene therapy is rapidly developing and holds potential as a prospective treatment option. Soon its efficacy and safety in patients with FXS will be demonstrated. WHAT THIS PAPER ADDS: Targeted treatment of fragile X syndrome (FXS) is the best current therapeutic approach. Gene therapy holds potential as a prospective treatment for FXS in the future.
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Affiliation(s)
- Dragana Protic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine University of Belgrade, Belgrade, Serbia
- Fragile X Clinic, Special Hospital for Cerebral Palsy and Developmental Neurology, Belgrade, Serbia
| | - Randi Hagerman
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, CA, USA
- Department of Pediatrics, University of California, Davis School of Medicine, Sacramento, CA, USA
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Zhan X, Asmara H, Pfaffinger P, Turner RW. Calcium-Dependent Regulation of Neuronal Excitability Is Rescued in Fragile X Syndrome by a Tat-Conjugated N-Terminal Fragment of FMRP. J Neurosci 2024; 44:e0136242024. [PMID: 38664011 PMCID: PMC11112635 DOI: 10.1523/jneurosci.0136-24.2024] [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: 01/18/2024] [Revised: 04/04/2024] [Accepted: 04/12/2024] [Indexed: 05/24/2024] Open
Abstract
Fragile X syndrome (FXS) arises from the loss of fragile X messenger ribonucleoprotein (FMRP) needed for normal neuronal excitability and circuit functions. Recent work revealed that FMRP contributes to mossy fiber long-term potentiation by adjusting the Kv4 A-type current availability through interactions with a Cav3-Kv4 ion channel complex, yet the mechanism has not yet been defined. In this study using wild-type and Fmr1 knock-out (KO) tsA-201 cells and cerebellar sections from male Fmr1 KO mice, we show that FMRP associates with all subunits of the Cav3.1-Kv4.3-KChIP3 complex and is critical to enabling calcium-dependent shifts in Kv4.3 inactivation to modulate the A-type current. Specifically, upon depolarization Cav3 calcium influx activates dual-specific phosphatase 1/6 (DUSP1/6) to deactivate ERK1/2 (ERK) and lower phosphorylation of Kv4.3, a signaling pathway that does not function in Fmr1 KO cells. In Fmr1 KO mouse tissue slices, cerebellar granule cells exhibit a hyperexcitable response to membrane depolarizations. Either incubating Fmr1 KO cells or in vivo administration of a tat-conjugated FMRP N-terminus fragment (FMRP-N-tat) rescued Cav3-Kv4 function and granule cell excitability, with a decrease in the level of DUSP6. Together these data reveal a Cav3-activated DUSP signaling pathway critical to the function of a FMRP-Cav3-Kv4 complex that is misregulated in Fmr1 KO conditions. Moreover, FMRP-N-tat restores function of this complex to rescue calcium-dependent control of neuronal excitability as a potential therapeutic approach to alleviating the symptoms of FXS.
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Affiliation(s)
- Xiaoqin Zhan
- Hotchkiss Brain Institute, Baylor College of Medicine, Houston, Texas 77030
- Alberta Children's Hospital Research Institute, Baylor College of Medicine, Houston, Texas 77030
| | - Hadhimulya Asmara
- Hotchkiss Brain Institute, Baylor College of Medicine, Houston, Texas 77030
- Alberta Children's Hospital Research Institute, Baylor College of Medicine, Houston, Texas 77030
| | - Paul Pfaffinger
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Ray W Turner
- Hotchkiss Brain Institute, Baylor College of Medicine, Houston, Texas 77030
- Alberta Children's Hospital Research Institute, Baylor College of Medicine, Houston, Texas 77030
- Department Clinical Neurosciences, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Malone TJ, Wu J, Zhang Y, Licznerski P, Chen R, Nahiyan S, Pedram M, Jonas EA, Kaczmarek LK. Neuronal potassium channel activity triggers initiation of mRNA translation through binding of translation regulators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.07.579306. [PMID: 38370631 PMCID: PMC10871293 DOI: 10.1101/2024.02.07.579306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Neuronal activity stimulates mRNA translation crucial for learning and development. While FMRP (Fragile X Mental Retardation Protein) and CYFIP1 (Cytoplasmic FMR1 Interacting Protein 1) regulate translation, the mechanism linking translation to neuronal activity is not understood. We now find that translation is stimulated when FMRP and CYFIP1 translocate to the potassium channel Slack (KCNT1, Slo2.2). When Slack is activated, both factors are released from eIF4E (Eukaryotic Initiation Factor 4E), where they normally inhibit translation initiation. A constitutively active Slack mutation and pharmacological stimulation of the wild-type channel both increase binding of FMRP and CYFIP1 to the channel, enhancing the translation of a reporter for β-actin mRNA in cell lines and the synthesis of β-actin in neuronal dendrites. Slack activity-dependent translation is abolished when both FMRP and CYFIP1 expression are suppressed. The effects of Slack mutations on activity-dependent translation may explain the severe intellectual disability produced by these mutations in humans. HIGHLIGHTS Activation of Slack channels triggers translocation of the FMRP/CYFIP1 complexSlack channel activation regulates translation initiation of a β-actin reporter constructA Slack gain-of-function mutation increases translation of β-actin reporter construct and endogenous cortical β-actinFMRP and CYFIP1 are required for Slack activity-dependent translation. IN BRIEF Malone et al . show that the activation of Slack channels triggers translocation of the FMRP/CYFIP1 complex from the translation initiation factor eIF4E to the channel. This translocation releases eIF4E and stimulates mRNA translation of a reporter for β-actin and cortical β-actin mRNA, elucidating the mechanism that connects neuronal activity with translational regulation.
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Shao N, Ye T, Xuan W, Zhang M, Chen Q, Liu J, Zhou P, Song H, Cai B. The effects of N 6-methyladenosine RNA methylation on the nervous system. Mol Cell Biochem 2023; 478:2657-2669. [PMID: 36899139 DOI: 10.1007/s11010-023-04691-6] [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: 03/19/2022] [Accepted: 02/24/2023] [Indexed: 03/12/2023]
Abstract
Epitranscriptomics, also known as "RNA epigenetics", is a type of chemical modification that regulates RNA. RNA methylation is a significant discovery after DNA and histone methylation. The dynamic reversible process of m6A involves methyltransferases (writers), m6A binding proteins (readers), as well as demethylases (erasers). We summarized the current research status of m6A RNA methylation in the neural stem cells' growth, synaptic and axonal function, brain development, learning and memory, neurodegenerative diseases, and glioblastoma. This review aims to provide a theoretical basis for studying the mechanism of m6A methylation and finding its potential therapeutic targets in nervous system diseases.
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Affiliation(s)
- Nan Shao
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China
| | - Ting Ye
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China
| | - Weiting Xuan
- Department of Neurosurgery (Rehabilitation), Anhui Hospital of Integrated Chinese and Western Medicine, Hefei, 230031, China
| | - Meng Zhang
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China
| | - Qian Chen
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China
| | - Juan Liu
- Department of Chinese Internal Medicine, Taihe County People's Hospital, Fuyang, 236699, China
| | - Peng Zhou
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Institute of Integrated Chinese and Western Medicine, Anhui Academy of Chinese Medicine, Hefei, 230012, China.
- Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Anhui Province Key Laboratory of Chinese Medicinal Formula, Hefei, 230012, China.
| | - Hang Song
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Institute of Integrated Chinese and Western Medicine, Anhui Academy of Chinese Medicine, Hefei, 230012, China.
- Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Anhui Province Key Laboratory of Chinese Medicinal Formula, Hefei, 230012, China.
| | - Biao Cai
- College of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Institute of Integrated Chinese and Western Medicine, Anhui Academy of Chinese Medicine, Hefei, 230012, China.
- Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Anhui Province Key Laboratory of Chinese Medicinal Formula, Hefei, 230012, China.
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Zhao S, Jiang X, Han L, Jiang Y, Wang Y, Meng J, Zhu X, Zhang X, Luo H, Zhang YW. Tau reduction attenuates autism-like features in Fmr1 knockout mice. Mol Autism 2023; 14:42. [PMID: 37936174 PMCID: PMC10629153 DOI: 10.1186/s13229-023-00574-1] [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: 07/19/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Fragile X syndrome (FXS) is a leading cause of autism spectrum disorder (ASD) and resulted from a loss of the FMR1-encoded fragile X messenger ribonucleoprotein 1 (FMRP) protein due to large CGG repeat expansions in the promoter region of the FMR1 gene. The microtubule-associated protein Tau is a promising target for Tauopathic diseases and our preliminary study found that Tau protein levels were increased in the brain of Fmr1 knockout (KO) mice, a model of FXS. However, whether Tau reduction can prevent autism-like features in Fmr1 KO mice and become a novel strategy for FXS treatment remain unknown. METHODS Tau was genetically reduced in Fmr1 KO mice through crossing Fmr1± female mice with Mapt± male mice. The male offspring with different genotypes were subjected to various autism-related behavioral tests, RNA sequencing, and biochemical analysis. Fmr1 KO male mice were treated with Tau-targeting antisense oligonucleotide (ASO) and then subjected to behavioral tests and biochemical analysis. RESULTS Tau expression was increased in the cortex of Fmr1 KO mice. Genetically reducing Tau prevented social defects, stereotyped and repetitive behavior, and spine abnormality in Fmr1 KO mice. Tau reduction also reversed increased periodic activity and partially rescued Per1 expression reduction in Fmr1 KO mice. Moreover, Tau reduction reversed compromised P38/MAPK signaling in Fmr1 KO mice. Finally, Tau-targeting ASO also effectively alleviated autism-like phenotypes and promoted P38/MAPK signaling in Fmr1 KO mice. LIMITATIONS Our study is limited to male mice, in agreement with the higher incidence of FXS in males than females. Whether Tau reduction also exerts protection in females deserves further scrutiny. Moreover, although Tau reduction rescues impaired P38/MAPK signaling in Fmr1 KO mice, whether this is the responsible molecular mechanism requires further determination. CONCLUSION Our data indicate that Tau reduction prevents autism-like phenotypes in Fmr1 KO mice. Tau may become a new target for FXS treatment.
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Affiliation(s)
- Shanshan Zhao
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Xiangyu Jiang
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Linkun Han
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Yiru Jiang
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Yong Wang
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Jian Meng
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Xiang Zhu
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Xian Zhang
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Hong Luo
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Yun-Wu Zhang
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China.
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Filandrova R, Douglas P, Zhan X, Verhey TB, Morrissy S, Turner RW, Schriemer DC. Mouse Model of Fragile X Syndrome Analyzed by Quantitative Proteomics: A Comparison of Methods. J Proteome Res 2023; 22:3054-3067. [PMID: 37595185 DOI: 10.1021/acs.jproteome.3c00363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
Multiple methods for quantitative proteomics are available for proteome profiling. It is unclear which methods are most useful in situations involving deep proteome profiling and the detection of subtle distortions in the proteome. Here, we compared the performance of seven different strategies in the analysis of a mouse model of Fragile X Syndrome, involving the knockout of the fmr1 gene that is the leading cause of autism spectrum disorder. Focusing on the cerebellum, we show that data-independent acquisition (DIA) and the tandem mass tag (TMT)-based real-time search method (RTS) generated the most informative profiles, generating 334 and 329 significantly altered proteins, respectively, although the latter still suffered from ratio compression. Label-free methods such as BoxCar and a conventional data-dependent acquisition were too noisy to generate a reliable profile, while TMT methods that do not invoke RTS showed a suppressed dynamic range. The TMT method using the TMTpro reagents together with complementary ion quantification (ProC) overcomes ratio compression, but current limitations in ion detection reduce sensitivity. Overall, both DIA and RTS uncovered known regulators of the syndrome and detected alterations in calcium signaling pathways that are consistent with calcium deregulation recently observed in imaging studies. Data are available via ProteomeXchange with the identifier PXD039885.
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Affiliation(s)
- Ruzena Filandrova
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Pauline Douglas
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Xiaoqin Zhan
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Theodore B Verhey
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Sorana Morrissy
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Raymond W Turner
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Chadman KK, Adayev T, Udayan A, Ahmed R, Dai CL, Goodman JH, Meeker H, Dolzhanskaya N, Velinov M. Efficient Delivery of FMR1 across the Blood Brain Barrier Using AAVphp Construct in Adult FMR1 KO Mice Suggests the Feasibility of Gene Therapy for Fragile X Syndrome. Genes (Basel) 2023; 14:505. [PMID: 36833432 PMCID: PMC9957373 DOI: 10.3390/genes14020505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/19/2023] Open
Abstract
Background Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism. Gene therapy may offer an efficient method to ameliorate the symptoms of this disorder. Methods An AAVphp.eb-hSyn-mFMR1IOS7 vector and an empty control were injected into the tail vein of adult Fmr1 knockout (KO) mice and wildtype (WT) controls. The KO mice were injected with 2 × 1013 vg/kg of the construct. The control KO and WT mice were injected with an empty vector. Four weeks following treatment, the animals underwent a battery of tests: open field, marble burying, rotarod, and fear conditioning. The mouse brains were studied for levels of the Fmr1 product FMRP. Results: No significant levels of FMRP were found outside the CNS in the treated animals. The gene delivery was highly efficient, and it exceeded the control FMRP levels in all tested brain regions. There was also improved performance in the rotarod test and partial improvements in the other tests in the treated KO animals. Conclusion: These experiments demonstrate efficient, brain-specific delivery of Fmr1 via peripheral administration in adult mice. The gene delivery led to partial alleviation of the Fmr1 KO phenotypical behaviors. FMRP oversupply may explain why not all behaviors were significantly affected. Since AAV.php vectors are less efficient in humans than in the mice used in the current experiment, studies to determine the optimal dose using human-suitable vectors will be necessary to further demonstrate feasibility.
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Affiliation(s)
- Kathryn K. Chadman
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Tatyana Adayev
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Aishwarya Udayan
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
- Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA
| | - Rida Ahmed
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
- Macaulay Honors College at Hunter CUNY, New York, NY 10065, USA
| | - Chun-Ling Dai
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Jeffrey H. Goodman
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Harry Meeker
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Natalia Dolzhanskaya
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Milen Velinov
- Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA
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Wang X, Fan Q, Yu X, Wang Y. Cellular distribution of the Fragile X mental retardation protein in the inner ear: a developmental and comparative study in the mouse, rat, gerbil, and chicken. J Comp Neurol 2023; 531:149-169. [PMID: 36222577 PMCID: PMC9691623 DOI: 10.1002/cne.25420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 09/08/2022] [Accepted: 09/16/2022] [Indexed: 11/11/2022]
Abstract
The Fragile X mental retardation protein (FMRP) is an mRNA binding protein that is essential for neural circuit assembly and synaptic plasticity. Loss of functional FMRP leads to Fragile X syndrome (FXS), a neurodevelopmental disorder characterized by sensory dysfunction including abnormal auditory processing. While the central mechanisms of FMRP regulation have been studied in the brain, whether FMRP is expressed in the auditory periphery and how it develops and functions remains unknown. In this study, we characterized the spatiotemporal distribution pattern of FMRP immunoreactivity in the inner ear of mice, rats, gerbils, and chickens. Across species, FMRP was expressed in hair cells and supporting cells, with a particularly high level in immature hair cells during the prehearing period. Interestingly, the distribution of cytoplasmic FMRP displayed an age-dependent translocation in hair cells, and this feature was conserved across species. In the auditory ganglion (AG), FMRP immunoreactivity was detected in neuronal cell bodies as well as their peripheral and central processes. Distinct from hair cells, FMRP intensity in AG neurons was high both during development and after maturation. Additionally, FMRP was evident in mature glial cells surrounding AG neurons. Together, these observations demonstrate distinct developmental trajectories across cell types in the auditory periphery. Given the importance of peripheral inputs to the maturation of auditory circuits, these findings implicate involvement of FMRP in inner ear development as well as a potential contribution of periphery FMRP to the generation of auditory dysfunction in FXS.
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Affiliation(s)
- Xiaoyu Wang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, College of Medicine, Jinan University, Guangzhou 510632, China
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Qiwei Fan
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, College of Medicine, Jinan University, Guangzhou 510632, China
| | - Xiaoyan Yu
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Yuan Wang
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
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D'Souza MN, Ramakrishna S, Radhakrishna BK, Jhaveri V, Ravindran S, Yeramala L, Nair D, Palakodeti D, Muddashetty RS. Function of FMRP Domains in Regulating Distinct Roles of Neuronal Protein Synthesis. Mol Neurobiol 2022; 59:7370-7392. [PMID: 36181660 DOI: 10.1007/s12035-022-03049-1] [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: 01/11/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022]
Abstract
The Fragile-X Mental Retardation Protein (FMRP) is an RNA binding protein that regulates translation of mRNAs essential for synaptic development and plasticity. FMRP interacts with a specific set of mRNAs, aids in their microtubule-dependent transport and regulates their translation through its association with ribosomes. However, the biochemical role of FMRP's domains in forming neuronal granules and associating with microtubules and ribosomes is currently undefined. We report that the C-terminus domain of FMRP is sufficient to bind to ribosomes akin to the full-length protein. Furthermore, the C-terminus domain alone is essential and responsible for FMRP-mediated neuronal translation repression. However, dendritic distribution of FMRP and its microtubule association is favored by the synergistic combination of FMRP domains rather than individual domains. Interestingly, we show that the phosphorylation of hFMRP at Serine-500 is important in modulating the dynamics of translation by controlling ribosome association. This is a fundamental mechanism governing the size and number of FMRP puncta that contain actively translating ribosomes. Finally through the use of pathogenic mutations, we emphasize the hierarchical contribution of FMRP's domains in translation regulation.
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Affiliation(s)
- Michelle Ninochka D'Souza
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India, 560065.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, India, 560064.,Centre for Brain Research, Indian Institute of Science, CV Raman Avenue, Bangalore, India, 560012
| | - Sarayu Ramakrishna
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India, 560065.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, India, 560064.,Centre for Brain Research, Indian Institute of Science, CV Raman Avenue, Bangalore, India, 560012
| | | | - Vishwaja Jhaveri
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India, 560065
| | - Sreenath Ravindran
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India, 560065
| | - Lahari Yeramala
- National Centre For Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India, 560065
| | - Deepak Nair
- Centre for Neuroscience, Indian Institute of Science, Bangalore, India, 560012
| | - Dasaradhi Palakodeti
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, India, 560065
| | - Ravi S Muddashetty
- Centre for Brain Research, Indian Institute of Science, CV Raman Avenue, Bangalore, India, 560012.
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11
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Zhan X, Drummond-Main C, Greening D, Yao J, Chen SWR, Appendino JP, Au PYB, Turner RW. Cannabidiol counters the effects of a dominant-negative pathogenic Kv7.2 variant. iScience 2022; 25:105092. [PMID: 36157585 PMCID: PMC9490039 DOI: 10.1016/j.isci.2022.105092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 08/17/2022] [Accepted: 09/02/2022] [Indexed: 11/04/2022] Open
Abstract
Epilepsy and neurodevelopmental disorders can arise from pathogenic variants of KCNQ (Kv7) channels. A patient with developmental and epileptic encephalopathy exhibited an in-frame deletion of histidine 260 on Kv7.2. Coexpression of Kv7.2 mutant (mut) subunits with Kv7.3 invoked a decrease in current density, a depolarizing shift in voltage for activation, and a decrease in membrane conductance. Biotinylation revealed an increased level of surface Kv7.2mut compared to Kv7.3 with no change in total membrane protein expression. Super-resolution and FRET imaging confirmed heteromeric channel formation and a higher expression density of Kv7.2mut. Cannabidiol (1 μM) offset the effects of Kv7.2mut by inducing a hyperpolarizing shift in voltage for activation independent of CB1 or CB2 receptors. These data reveal that the ability for cannabidiol to reduce the effects of a pathogenic Kv7.2 variant supports its use as a potential therapeutic to reduce seizure activity. A patient with epileptic encephalopathy exhibits a Kv7.2 deletion at H260 (Kv7.2mut) Kv7.2mut shows increased expression at the membrane compared to Kv7.3 Kv7.2mut acts in a dominant-negative manner to reduce Kv7 conductance Cannabidiol acts on Kv7.x activation voltage to offset the effects of Kv7.2mut
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Affiliation(s)
- Xiaoqin Zhan
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Chris Drummond-Main
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Dylan Greening
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Jinjing Yao
- Libin Cardiovascular Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - S W R Chen
- Libin Cardiovascular Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - J P Appendino
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Pediatric Department, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - P Y Billie Au
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Department of Medical Genetics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ray W Turner
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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12
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Malone TJ, Kaczmarek LK. The role of altered translation in intellectual disability and epilepsy. Prog Neurobiol 2022; 213:102267. [PMID: 35364140 PMCID: PMC10583652 DOI: 10.1016/j.pneurobio.2022.102267] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 02/18/2022] [Accepted: 03/24/2022] [Indexed: 11/29/2022]
Abstract
A very high proportion of cases of intellectual disability are genetic in origin and are associated with the occurrence of epileptic seizures during childhood. These two disorders together effect more than 5% of the world's population. One feature linking the two diseases is that learning and memory require the synthesis of new synaptic components and ion channels, while maintenance of overall excitability also requires synthesis of similar proteins in response to altered neuronal stimulation. Many of these disorders result from mutations in proteins that regulate mRNA processing, translation initiation, translation elongation, mRNA stability or upstream translation modulators. One theme that emerges on reviewing this field is that mutations in proteins that regulate changes in translation following neuronal stimulation are more likely to result in epilepsy with intellectual disability than general translation regulators with no known role in activity-dependent changes. This is consistent with the notion that activity-dependent translation in neurons differs from that in other cells types in that the changes in local cellular composition, morphology and connectivity that occur generally in response to stimuli are directly coupled to local synaptic activity and persist for months or years after the original stimulus.
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Affiliation(s)
- Taylor J Malone
- Departments of Pharmacology, and of Cellular & Molecular Physiology, Yale University, 333 Cedar Street B-309, New Haven, CT 06520, USA
| | - Leonard K Kaczmarek
- Departments of Pharmacology, and of Cellular & Molecular Physiology, Yale University, 333 Cedar Street B-309, New Haven, CT 06520, USA.
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13
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Deng PY, Kumar A, Cavalli V, Klyachko VA. FMRP regulates GABA A receptor channel activity to control signal integration in hippocampal granule cells. Cell Rep 2022; 39:110820. [PMID: 35584668 DOI: 10.1016/j.celrep.2022.110820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/11/2022] [Accepted: 04/21/2022] [Indexed: 11/29/2022] Open
Abstract
Fragile X syndrome, the most common inherited form of intellectual disability, is caused by loss of fragile X mental retardation protein (FMRP). GABAergic system dysfunction is one of the hallmarks of FXS, yet the underlying mechanisms remain poorly understood. Here, we report that FMRP interacts with GABAA receptor (GABAAR) and modulates its single-channel activity. Specifically, FMRP regulates spontaneous GABAAR opening through modulating its single-channel conductance and open probability in dentate granule cells. FMRP loss reduces spontaneous GABAAR activity underlying tonic inhibition, while N-terminal FMRP fragment (aa 1-297) is sufficient to rapidly normalize tonic inhibition in Fmr1 knockout (KO) granule cells. FMRP-GABAAR interaction is supported by co-immunoprecipitation of FMRP with at least one GABAAR subunit, the α5. Functionally, FMRP-GABAAR interaction ensures accuracy of coincidence detection of granule cells, which is markedly reduced in Fmr1 KOs. Our study reveals a mechanism underlying FMRP regulation of the GABAergic system and information processing in the hippocampus.
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Affiliation(s)
- Pan-Yue Deng
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Ajeet Kumar
- Department of Neuroscience, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Valeria Cavalli
- Department of Neuroscience, Washington University School of Medicine, St Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Vitaly A Klyachko
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA.
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14
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Sotoudeh Anvari M, Vasei H, Najmabadi H, Badv RS, Golipour A, Mohammadi-Yeganeh S, Salehi S, Mohamadi M, Goodarzynejad H, Mowla SJ. Identification of microRNAs associated with human fragile X syndrome using next-generation sequencing. Sci Rep 2022; 12:5011. [PMID: 35322102 PMCID: PMC8943156 DOI: 10.1038/s41598-022-08916-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 03/15/2022] [Indexed: 11/09/2022] Open
Abstract
Fragile X syndrome (FXS) is caused by a mutation in the FMR1 gene which can lead to a loss or shortage of the FMR1 protein. This protein interacts with specific miRNAs and can cause a range of neurological disorders. Therefore, miRNAs could act as a novel class of biomarkers for common CNS diseases. This study aimed to test this theory by exploring the expression profiles of various miRNAs in Iranian using deep sequencing-based technologies and validating the miRNAs affecting the expression of the FMR1 gene. Blood samples were taken from 15 patients with FXS (9 males, 6 females) and 12 controls. 25 miRNAs were differentially expressed in individuals with FXS compared to controls. Levels of 9 miRNAs were found to be significantly changed (3 upregulated and 6 downregulated). In Patients, the levels of hsa-miR-532-5p, hsa-miR-652-3p and hsa-miR-4797-3p were significantly upregulated while levels of hsa-miR-191-5p, hsa-miR-181-5p, hsa-miR-26a-5p, hsa-miR-30e-5p, hsa-miR-186-5p, and hsa-miR-4797-5p exhibited significant downregulation; and these dysregulations were confirmed by RT-qPCR. This study presents among the first evidence of altered miRNA expression in blood samples from patients with FXS, which could be used for diagnostic, prognostic, and treatment purposes. Larger studies are required to confirm these preliminary results.
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Affiliation(s)
- Maryam Sotoudeh Anvari
- Department of Molecular Pathology, School of Medicine, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran.
| | - Hamed Vasei
- Department of Mathematical Science, Sharif University of Technology, Tehran, Iran
| | - Hossein Najmabadi
- Department of Genetics, School of Rehabilitation Sciences, Genetic Research Center, The University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Reza Shervin Badv
- Department of Pediatrics, School of Medicine, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Akram Golipour
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Samira Mohammadi-Yeganeh
- Medical Nanotechnology and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Saeede Salehi
- Cell-Based Therapies Research Center, Digestive Diseases Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahmood Mohamadi
- Department of Pediatrics, School of Medicine, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Hamidreza Goodarzynejad
- Department of Basic and Clinical Research, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Javad Mowla
- Department of Molecular Genetics, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran.
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15
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Liu X, Kumar V, Tsai NP, Auerbach BD. Hyperexcitability and Homeostasis in Fragile X Syndrome. Front Mol Neurosci 2022; 14:805929. [PMID: 35069112 PMCID: PMC8770333 DOI: 10.3389/fnmol.2021.805929] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/14/2021] [Indexed: 01/13/2023] Open
Abstract
Fragile X Syndrome (FXS) is a leading inherited cause of autism and intellectual disability, resulting from a mutation in the FMR1 gene and subsequent loss of its protein product FMRP. Despite this simple genetic origin, FXS is a phenotypically complex disorder with a range of physical and neurocognitive disruptions. While numerous molecular and cellular pathways are affected by FMRP loss, there is growing evidence that circuit hyperexcitability may be a common convergence point that can account for many of the wide-ranging phenotypes seen in FXS. The mechanisms for hyperexcitability in FXS include alterations to excitatory synaptic function and connectivity, reduced inhibitory neuron activity, as well as changes to ion channel expression and conductance. However, understanding the impact of FMR1 mutation on circuit function is complicated by the inherent plasticity in neural circuits, which display an array of homeostatic mechanisms to maintain activity near set levels. FMRP is also an important regulator of activity-dependent plasticity in the brain, meaning that dysregulated plasticity can be both a cause and consequence of hyperexcitable networks in FXS. This makes it difficult to separate the direct effects of FMR1 mutation from the myriad and pleiotropic compensatory changes associated with it, both of which are likely to contribute to FXS pathophysiology. Here we will: (1) review evidence for hyperexcitability and homeostatic plasticity phenotypes in FXS models, focusing on similarities/differences across brain regions, cell-types, and developmental time points; (2) examine how excitability and plasticity disruptions interact with each other to ultimately contribute to circuit dysfunction in FXS; and (3) discuss how these synaptic and circuit deficits contribute to disease-relevant behavioral phenotypes like epilepsy and sensory hypersensitivity. Through this discussion of where the current field stands, we aim to introduce perspectives moving forward in FXS research.
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Affiliation(s)
- Xiaopeng Liu
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Beckman Institute for Advanced Science & Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Vipendra Kumar
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Nien-Pei Tsai
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Benjamin D. Auerbach
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Beckman Institute for Advanced Science & Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- *Correspondence: Benjamin D. Auerbach
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16
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Abstract
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability and the leading monogenic cause of autism. The condition stems from loss of fragile X mental retardation protein (FMRP), which regulates a wide range of ion channels via translational control, protein-protein interactions and second messenger pathways. Rapidly increasing evidence demonstrates that loss of FMRP leads to numerous ion channel dysfunctions (that is, channelopathies), which in turn contribute significantly to FXS pathophysiology. Consistent with this, pharmacological or genetic interventions that target dysregulated ion channels effectively restore neuronal excitability, synaptic function and behavioural phenotypes in FXS animal models. Recent studies further support a role for direct and rapid FMRP-channel interactions in regulating ion channel function. This Review lays out the current state of knowledge in the field regarding channelopathies and the pathogenesis of FXS, including promising therapeutic implications.
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17
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Light-regulated voltage-gated potassium channels for acute interrogation of channel function in neurons and behavior. PLoS One 2021; 16:e0248688. [PMID: 33755670 PMCID: PMC7987177 DOI: 10.1371/journal.pone.0248688] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 03/03/2021] [Indexed: 01/02/2023] Open
Abstract
Voltage-gated potassium (Kv) channels regulate the membrane potential and conductance of excitable cells to control the firing rate and waveform of action potentials. Even though Kv channels have been intensely studied for over 70 year, surprisingly little is known about how specific channels expressed in various neurons and their functional properties impact neuronal network activity and behavior in vivo. Although many in vivo genetic manipulations of ion channels have been tried, interpretation of these results is complicated by powerful homeostatic plasticity mechanisms that act to maintain function following perturbations in excitability. To better understand how Kv channels shape network function and behavior, we have developed a novel optogenetic technology to acutely regulate Kv channel expression with light by fusing the light-sensitive LOV domain of Vaucheria frigida Aureochrome 1 to the N-terminus of the Kv1 subunit protein to make an Opto-Kv1 channel. Recording of Opto-Kv1 channels expressed in Xenopus oocytes, mammalian cells, and neurons show that blue light strongly induces the current expression of Opto-Kv1 channels in all systems tested. We also find that an Opto-Kv1 construct containing a dominant-negative pore mutation (Opto-Kv1(V400D)) can be used to down-regulate Kv1 currents in a blue light-dependent manner. Finally, to determine whether Opto-Kv1 channels can elicit light-dependent behavioral effect in vivo, we targeted Opto-Kv1 (V400D) expression to Kv1.3-expressing mitral cells of the olfactory bulb in mice. Exposure of the bulb to blue light for 2–3 hours produced a significant increase in sensitivity to novel odors after initial habituation to a similar odor, comparable to behavioral changes seen in Kv1.3 knockout animals. In summary, we have developed novel photoactivatable Kv channels that provide new ways to interrogate neural circuits in vivo and to examine the roles of normal and disease-causing mutant Kv channels in brain function and behavior.
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18
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The life cycle of voltage-gated Ca 2+ channels in neurons: an update on the trafficking of neuronal calcium channels. Neuronal Signal 2021; 5:NS20200095. [PMID: 33664982 PMCID: PMC7905535 DOI: 10.1042/ns20200095] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/10/2021] [Accepted: 02/15/2021] [Indexed: 01/26/2023] Open
Abstract
Neuronal voltage-gated Ca2+ (CaV) channels play a critical role in cellular excitability, synaptic transmission, excitation-transcription coupling and activation of intracellular signaling pathways. CaV channels are multiprotein complexes and their functional expression in the plasma membrane involves finely tuned mechanisms, including forward trafficking from the endoplasmic reticulum (ER) to the plasma membrane, endocytosis and recycling. Whether genetic or acquired, alterations and defects in the trafficking of neuronal CaV channels can have severe physiological consequences. In this review, we address the current evidence concerning the regulatory mechanisms which underlie precise control of neuronal CaV channel trafficking and we discuss their potential as therapeutic targets.
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