1
|
Wong H, Hooper AW, Kang HR, Lee SJ, Zhao J, Sadhu C, Rawat S, Gray SJ, Hampson DR. CNS-dominant human FMRP isoform rescues seizures, fear, and sleep abnormalities in Fmr1-KO mice. JCI Insight 2023; 8:169650. [PMID: 37288657 PMCID: PMC10393223 DOI: 10.1172/jci.insight.169650] [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: 02/15/2023] [Accepted: 04/18/2023] [Indexed: 06/09/2023] Open
Abstract
Fragile X syndrome is a neurodevelopmental disorder caused by the absence of the mRNA-binding protein fragile X messenger ribonucleoprotein (FMRP). Because FMRP is a highly pleiotropic protein controlling the expression of hundreds of genes, viral vector-mediated gene replacement therapy is viewed as a potential viable treatment to correct the fundamental underlying molecular pathology inherent in the disorder. Here, we studied the safety profile and therapeutic effects of a clinically relevant dose of a self-complementary adeno-associated viral (AAV) vector containing a major human brain isoform of FMRP after intrathecal injection into wild-type and fragile X-KO mice. Analysis of the cellular transduction in the brain indicated primarily neuronal transduction with relatively sparse glial expression, similar to endogenous FMRP expression in untreated wild-type mice. AAV vector-treated KO mice showed recovery from epileptic seizures, normalization of fear conditioning, reversal of slow-wave deficits as measured via electroencephalographic recordings, and restoration of abnormal circadian motor activity and sleep. Further assessment of vector efficacy by tracking and analyzing individual responses demonstrated correlations between the level and distribution of brain transduction and drug response. These preclinical findings further demonstrate the validity of AAV vector-mediated gene therapy for treating the most common genetic cause of cognitive impairment and autism in children.
Collapse
Affiliation(s)
- Hayes Wong
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Alexander Wm Hooper
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Hye Ri Kang
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Shiron J Lee
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Jiayi Zhao
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | | | | | - Steven J Gray
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - David R Hampson
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
2
|
Hooper AW, Wong H, Niibori Y, Abdoli R, Karumuthil-Melethil S, Qiao C, Danos O, Bruder JT, Hampson DR. Gene therapy using an ortholog of human fragile X mental retardation protein partially rescues behavioral abnormalities and EEG activity. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 22:196-209. [PMID: 34485605 PMCID: PMC8399347 DOI: 10.1016/j.omtm.2021.06.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/30/2021] [Indexed: 01/28/2023]
Abstract
Fragile X syndrome (FXS), a neurodevelopmental disorder with no known cure, is caused by a lack of expression of the fragile X mental retardation protein (FMRP). As a single-gene disorder, FXS is an excellent candidate for viral-vector-based gene therapy, although that is complicated by the existence of multiple isoforms of FMRP, whose individual cellular functions are unknown. We studied the effects of rat and mouse orthologs of human isoform 17, a major expressed isoform of FMRP. Injection of neonatal Fmr1 knockout rats and mice with adeno-associated viral vectors (AAV9 serotype) under the control of an MeCP2 mini-promoter resulted in widespread distribution of the FMRP transgenes throughout the telencephalon and diencephalon. Transgene expression occurred mainly in non-GABAergic neurons, with little expression in glia. Early postnatal treatment resulted in partial rescue of the Fmr1 KO rat phenotype, including improved social dominance in treated Fmr1 KO females and partial rescue of locomotor activity in males. Electro-encephalogram (EEG) recordings showed correction of abnormal slow-wave activity during the sleep-like state in male Fmr1 KO rats. These findings support the use of AAV-based gene therapy as a treatment for FXS and specifically demonstrate the potential therapeutic benefit of human FMRP isoform 17 orthologs.
Collapse
Affiliation(s)
- Alexander W.M. Hooper
- Leslie Dan Faculty of Pharmacy, Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| | - Hayes Wong
- Leslie Dan Faculty of Pharmacy, Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| | - Yosuke Niibori
- Leslie Dan Faculty of Pharmacy, Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| | - Rozita Abdoli
- Leslie Dan Faculty of Pharmacy, Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| | | | - Chunping Qiao
- Research and Early Development, REGENXBIO Inc. Rockville, Maryland, U.S.A. 20850
| | - Olivier Danos
- Research and Early Development, REGENXBIO Inc. Rockville, Maryland, U.S.A. 20850
| | - Joseph T. Bruder
- Research and Early Development, REGENXBIO Inc. Rockville, Maryland, U.S.A. 20850
| | - David R. Hampson
- Leslie Dan Faculty of Pharmacy, Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3M2
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada M5S 3M2
- Corresponding author: David R. Hampson, PhD, Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, Univerity of Toronto, ON M5S 3M2, Canada.
| |
Collapse
|
3
|
Zafarullah M, Tang HT, Durbin-Johnson B, Fourie E, Hessl D, Rivera SM, Tassone F. FMR1 locus isoforms: potential biomarker candidates in fragile X-associated tremor/ataxia syndrome (FXTAS). Sci Rep 2020; 10:11099. [PMID: 32632326 PMCID: PMC7338407 DOI: 10.1038/s41598-020-67946-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 05/18/2020] [Indexed: 12/12/2022] Open
Abstract
Fragile X associated tremor/ataxia syndrome (FXTAS) is a late adult-onset neurodegenerative disorder that affects movement and cognition in male and female carriers of a premutation allele of 55-200 CGG repeats in the Fragile X mental retardation (FMR1) gene. It is currently unknown if and when an individual carrier of a premutation allele will develop FXTAS, as clinical assessment fails to identify carriers at risk before significant neurological symptoms are evident. The primary objective of this study was to investigate the alternative splicing landscape at the FMR1 locus in conjunction with brain measures in male individuals with a premutation allele enrolled in a very first longitudinal study, compared to age-matched healthy male controls, with the purpose of identifying biomarkers for early diagnosis, disease prediction and, a progression of FXTAS. Our findings indicate that increased expression of FMR1 mRNA isoforms, including Iso4/4b, Iso10/10b, as well as of the ASFMR1 mRNAs Iso131bp, are present in premutation carriers as compared to non-carrier healthy controls. More specifically, we observed a higher expression of Iso4/4b and Iso10/10b, which encode for truncated proteins, only in those premutation carriers who developed symptoms of FXTAS over time as compared to non-carrier healthy controls, suggesting a potential role in the development of the disorder. In addition, we found a significant association of these molecular changes with various measurements of brain morphology, including the middle cerebellar peduncle (MCP), superior cerebellar peduncle (SCP), pons, and midbrain, indicating their potential contribution to the pathogenesis of FXTAS. Interestingly, the high expression levels of Iso4/4b observed both at visit 1 and visit 2 and found to be associated with a decrease in mean MCP width only in those individuals who developed FXTAS over time, suggests their role as potential biomarkers for early diagnosis of FXTAS.
Collapse
Affiliation(s)
- Marwa Zafarullah
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, 95817 CA, USA
| | - Hiu-Tung Tang
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, 95817 CA, USA
| | - Blythe Durbin-Johnson
- Division of Biostatistics, School of Medicine, University of California Davis, Davis, CA, USA
| | - Emily Fourie
- Center for Mind and Brain, University of California Davis, Davis, CA, USA
- Department of Psychology, University of California, Davis, Davis, CA, USA
| | - David Hessl
- MIND Institute, University of California Davis Medical Center, Sacramento, 95817 CA, USA
- Department of Psychiatry and Behavioral Sciences, University of California Davis Medical Center, Sacramento, 95817 CA, USA
| | - Susan M Rivera
- Center for Mind and Brain, University of California Davis, Davis, CA, USA
- Department of Psychology, University of California, Davis, Davis, CA, USA
- MIND Institute, University of California Davis Medical Center, Sacramento, 95817 CA, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, 95817 CA, USA.
- MIND Institute, University of California Davis Medical Center, Sacramento, 95817 CA, USA.
| |
Collapse
|
4
|
Fu XG, Yan AZ, Xu YJ, Liao J, Guo XY, Zhang D, Yang WJ, Zheng DZ, Lan FH. Splicing of exon 9a in FMR1 transcripts results in a truncated FMRP with altered subcellular distribution. Gene 2020; 731:144359. [PMID: 31935509 DOI: 10.1016/j.gene.2020.144359] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/13/2022]
Abstract
FMRP is an RNA-binding protein, loss of which causes fragile X syndrome (FXS). FMRP has several isoforms resulted from alternative splicing (AS) of fragile X mental retardation 1 (FMR1) gene, but their biological functions are still poorly understood. In the analysis of alternatively spliced FMR1 transcripts in the blood cells from a patient with FXS-like phenotypes (normal CGG repeats and no mutation in coding sequence of FMR1), we identified three novel FMR1 transcripts that include a previously unidentified microexon (46 bp), terming the exon 9a. This microexon exists widely in unaffected individuals, inclusion of which introduces an in-frame termination codon. To address whether these exon 9a-containing transcripts could produce protein by evading nonsense-mediated decay (NMD), Western blot was used to analysis blood cell lysate from unaffected individuals and a 34 kDa protein that consistent in size with the molecular weight of the predicted truncated protein produced from mRNA with this microexon was found. Meanwhile, treatment of peripheral blood mononuclear cells with an inhibitor of NMD (Cycloheximide) did not result in significant increase in exon 9a-containing transcripts. Using confocal immunofluorescence, we found the truncated protein displayed both nuclear and cytoplasmic localization in HEK293T and HeLa cells due to lacking C-terminal domains including KH2, NES, and RGG, while the full-length FMRP protein mainly localized in the cytoplasm. Therefore, we hypothesize that the inclusion of this microexon to generate exon 9a-containing transcripts may regulate the normal functionality of FMRP, and the dysregulation of normal FMRP due to increased exon 9a-containing alternatively spliced transcripts in that patient may be associated with the manifestation of FXS phenotype.
Collapse
Affiliation(s)
- Xian-Guo Fu
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Ai-Zhen Yan
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Yong-Jun Xu
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Juan Liao
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Xiao-Yan Guo
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Duo Zhang
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Wen-Jing Yang
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - De-Zhu Zheng
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China
| | - Feng-Hua Lan
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Fujian Medical University, Fuzhou, Fujian 350025, China.
| |
Collapse
|
5
|
The Application of Adeno-Associated Viral Vector Gene Therapy to the Treatment of Fragile X Syndrome. Brain Sci 2019; 9:brainsci9020032. [PMID: 30717399 PMCID: PMC6406794 DOI: 10.3390/brainsci9020032] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 01/18/2023] Open
Abstract
Viral vector-mediated gene therapy has grown by leaps and bounds over the past several years. Although the reasons for this progress are varied, a deeper understanding of the basic biology of the viruses, the identification of new and improved versions of viral vectors, and simply the vast experience gained by extensive testing in both animal models of disease and in clinical trials, have been key factors. Several studies have investigated the efficacy of adeno-associated viral (AAV) vectors in the mouse model of fragile X syndrome where AAVs have been used to express fragile X mental retardation protein (FMRP), which is missing or highly reduced in the disorder. These studies have demonstrated a range of efficacies in different tests from full correction, to partial rescue, to no effect. Here we provide a backdrop of recent advances in AAV gene therapy as applied to central nervous system disorders, outline the salient features of the fragile X studies, and discuss several key issues for moving forward. Collectively, the findings to date from the mouse studies on fragile X syndrome, and data from clinical trials testing AAVs in other neurological conditions, indicate that AAV-mediated gene therapy could be a viable strategy for treating fragile X syndrome.
Collapse
|