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Lockman S, Genung M, Sheikholeslami K, Sher AA, Kroft D, Buist M, Olson CO, Toor B, Rastegar M. Transcriptional Inhibition of the Mecp2 Promoter by MeCP2E1 and MeCP2E2 Isoforms Suggests Negative Auto-Regulatory Feedback that can be Moderated by Metformin. J Mol Neurosci 2024; 74:14. [PMID: 38277073 DOI: 10.1007/s12031-023-02177-0] [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: 08/31/2023] [Accepted: 12/29/2023] [Indexed: 01/27/2024]
Abstract
The epigenetic factor Methyl-CpG-Binding Protein 2 (MeCP2) is a nuclear protein that binds methylated DNA molecules (both 5-methylcytosine and 5-hydroxymethylcytosine) and controls gene transcription. MeCP2 is an important transcription factor that acts in a dose-dependent manner in the brain; thus, its optimal expression level in brain cells is important. As such, its deregulated expression, as well as gain- or loss-of-function mutation, lead to impaired neurodevelopment, and compromised structure and function of brain cells, particularly in neurons. Studies from others and us have characterized two well-recognized MeCP2 isoforms: MeCP2E1 and MeCP2E2. We have reported that in Daoy medulloblastoma brain cells, MeCP2E2 overexpression leads to MeCP2E1 protein degradation. Whether MeCP2 isoforms regulate the Mecp2 promoter regulatory elements remains unexplored. We previously showed that in Daoy cells, metformin (an anti-diabetic drug) induces MECP2E1 transcripts. However, possible impact of metformin on the Mecp2 promoter activity was not studied. Here, we generated stably transduced Daoy cell reporters to express EGFP driven by the Mecp2 promoter. Transduced cells were sorted into four EGFP-expressing groups (R4-to-R7) with different intensities of EGFP expression. Our results confirm that the Mecp2 promoter is active in Daoy cells, and that overexpression of either isoform inhibits the Mecp2 promoter activity, as detected by flow cytometry and luciferase reporter assays. Interestingly, metformin partially relieved the inhibitory effect of MeCP2E1 on the Mecp2 promoter, detected by flow cytometry. Taken together, our data provide important insight towards the regulation of MeCP2 isoforms at the promoter level, which might have biological relevance to the neurobiology of the brain.
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Affiliation(s)
- Sandhini Lockman
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Matthew Genung
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kimia Sheikholeslami
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Annan Ali Sher
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Daniel Kroft
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Marjorie Buist
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Carl O Olson
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Brian Toor
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
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MeCP2 and transcriptional control of eukaryotic gene expression. Eur J Cell Biol 2022; 101:151237. [DOI: 10.1016/j.ejcb.2022.151237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/30/2022] [Accepted: 05/09/2022] [Indexed: 11/19/2022] Open
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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: 13] [Impact Index Per Article: 4.3] [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.
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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.
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Rodrigues DC, Mufteev M, Ellis J. Regulation, diversity and function of MECP2 exon and 3'UTR isoforms. Hum Mol Genet 2021; 29:R89-R99. [PMID: 32681172 PMCID: PMC7530521 DOI: 10.1093/hmg/ddaa154] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/12/2020] [Accepted: 07/14/2020] [Indexed: 12/11/2022] Open
Abstract
The methyl-CpG-binding protein 2 (MECP2) is a critical global regulator of gene expression. Mutations in MECP2 cause neurodevelopmental disorders including Rett syndrome (RTT). MECP2 exon 2 is spliced into two alternative messenger ribonucleic acid (mRNA) isoforms encoding MECP2-E1 or MECP2-E2 protein isoforms that differ in their N-termini. MECP2-E2, isolated first, was used to define the general roles of MECP2 in methyl-deoxyribonucleic acid (DNA) binding, targeting of transcriptional regulatory complexes, and its disease-causing impact in RTT. It was later found that MECP2-E1 is the most abundant isoform in the brain and its exon 1 is also mutated in RTT. MECP2 transcripts undergo alternative polyadenylation generating mRNAs with four possible 3'untranslated region (UTR) lengths ranging from 130 to 8600 nt. Together, the exon and 3'UTR isoforms display remarkable abundance disparity across cell types and tissues during development. These findings indicate discrete means of regulation and suggest that protein isoforms perform non-overlapping roles. Multiple regulatory programs have been explored to explain these disparities. DNA methylation patterns of the MECP2 promoter and first intron impact MECP2-E1 and E2 isoform levels. Networks of microRNAs and RNA-binding proteins also post-transcriptionally regulate the stability and translation efficiency of MECP2 3'UTR isoforms. Finally, distinctions in biophysical properties in the N-termini between MECP2-E1 and E2 lead to variable protein stabilities and DNA binding dynamics. This review describes the steps taken from the discovery of MECP2, the description of its key functions, and its association with RTT, to the emergence of evidence revealing how MECP2 isoforms are differentially regulated at the transcriptional, post-transcriptional and post-translational levels.
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Affiliation(s)
- Deivid Carvalho Rodrigues
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto ON M5G 0A4, Canada
| | - Marat Mufteev
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto ON M5S 1A8, Canada
| | - James Ellis
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto ON M5S 1A8, Canada
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Wegmann S, DeVos SL, Zeitler B, Marlen K, Bennett RE, Perez-Rando M, MacKenzie D, Yu Q, Commins C, Bannon RN, Corjuc BT, Chase A, Diez L, Nguyen HOB, Hinkley S, Zhang L, Goodwin A, Ledeboer A, Lam S, Ankoudinova I, Tran H, Scarlott N, Amora R, Surosky R, Miller JC, Robbins AB, Rebar EJ, Urnov FD, Holmes MC, Pooler AM, Riley B, Zhang HS, Hyman BT. Persistent repression of tau in the brain using engineered zinc finger protein transcription factors. SCIENCE ADVANCES 2021; 7:7/12/eabe1611. [PMID: 33741591 PMCID: PMC7978433 DOI: 10.1126/sciadv.abe1611] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/05/2021] [Indexed: 05/12/2023]
Abstract
Neuronal tau reduction confers resilience against β-amyloid and tau-related neurotoxicity in vitro and in vivo. Here, we introduce a novel translational approach to lower expression of the tau gene MAPT at the transcriptional level using gene-silencing zinc finger protein transcription factors (ZFP-TFs). Following a single administration of adeno-associated virus (AAV), either locally into the hippocampus or intravenously to enable whole-brain transduction, we selectively reduced tau messenger RNA and protein by 50 to 80% out to 11 months, the longest time point studied. Sustained tau lowering was achieved without detectable off-target effects, overt histopathological changes, or molecular alterations. Tau reduction with AAV ZFP-TFs was able to rescue neuronal damage around amyloid plaques in a mouse model of Alzheimer's disease (APP/PS1 line). The highly specific, durable, and controlled knockdown of endogenous tau makes AAV-delivered ZFP-TFs a promising approach for the treatment of tau-related human brain diseases.
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Affiliation(s)
- Susanne Wegmann
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA.
- German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Sarah L DeVos
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | | | | | - Rachel E Bennett
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Marta Perez-Rando
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Danny MacKenzie
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Qi Yu
- Sangamo Therapeutics Inc., Richmond, CA 94804, USA
| | - Caitlin Commins
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Riley N Bannon
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Bianca T Corjuc
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Alison Chase
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | - Lisa Diez
- German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | | | | | - Lei Zhang
- Sangamo Therapeutics Inc., Richmond, CA 94804, USA
| | | | | | - Stephen Lam
- Sangamo Therapeutics Inc., Richmond, CA 94804, USA
| | | | - Hung Tran
- Sangamo Therapeutics Inc., Richmond, CA 94804, USA
| | | | | | | | | | - Ashley B Robbins
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA
| | | | | | | | - Amy M Pooler
- Sangamo Therapeutics Inc., Richmond, CA 94804, USA
| | - Brigit Riley
- Sangamo Therapeutics Inc., Richmond, CA 94804, USA
| | | | - Bradley T Hyman
- Massachusetts General Hospital, Massachusetts Institute of Neurodegenerative Disease, Charlestown, MA 02129, USA.
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Matagne V, Borloz E, Ehinger Y, Saidi L, Villard L, Roux JC. Severe offtarget effects following intravenous delivery of AAV9-MECP2 in a female mouse model of Rett syndrome. Neurobiol Dis 2020; 149:105235. [PMID: 33383186 DOI: 10.1016/j.nbd.2020.105235] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 12/18/2020] [Accepted: 12/26/2020] [Indexed: 01/06/2023] Open
Abstract
Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder that is primarily caused by mutations in the methyl CpG binding protein 2 gene (MECP2). RTT is the second most prevalent genetic cause of intellectual disability in girls, and there is currently no cure for the disease. We have previously shown that gene therapy using a self-complementary AAV9 viral vector expressing a codon-optimized Mecp2 version (AAV9-MCO) significantly improved symptoms and increased survival in male Mecp2-deficient mice. Here, we pursued our studies and investigated the safety and efficacy of long-term gene therapy in the genetically relevant RTT mouse model: the heterozygous (HET) Mecp2 deficient female mouse. These mice were injected with the AAV9-MCO vector through the tail vein and an array of behavioral tests was performed. At 16- and 30-weeks post-injection, this treatment was able to rescue apneas and improved the spontaneous locomotor deficits and circadian locomotor activity in Mecp2 HET mice treated with AAV9-MCO at a dose of 5 × 1011 vg/mouse. To examine whether a higher dose of vector could result in increased improvements, we injected Mecp2 HET mice with a higher MCO vector dose (1012 vg/mouse), which resulted in some severe, sometimes lethal, side effects. In order to confirm these effects, a new cohort of Mecp2 HET mice were administered increasing doses of MCO vector (1011, 5 × 1011 and 1012 vg/mouse). Again, two weeks after vector administration, some Mecp2 HET mice were found dead while others displayed severe side effects and had to be euthanized. These deleterious effects were not observed in Mecp2 HET mice injected with a high dose of AAV9-GFP and were directly proportionate to vector dosage (0, 23 or 54% mortality at an AAV9-MCO dose of 1011, 5 × 1011, 1012 vg/mouse, respectively), and no such lethality was observed in wild-type (WT) mice. In the Mecp2 HET mice treated with the high and medium AAV9-MCO doses, blood chemistry analysis and post-mortem histology showed liver damage with drastically elevated levels of liver transaminases and disorganized liver architecture. Apoptosis was confirmed by the presence of TUNEL- and cleaved-caspase 3-positive cells in the Mecp2 HET mice treated with the higher doses of AAV9-MCO. We then studied the involvement of the unfolded protein response (UPR) in triggering apoptosis since it can be activated by AAV vectors. Increased expression of the C/EBP homologous protein (CHOP), one of UPR downstream effectors, was confirmed in Mecp2 HET mice after vector administration. The toxic reaction seen in some treated mice indicates that, although gene therapy for RTT improved breathing deficits observed in Mecp2 HET mice, further studies are needed to better understand the underlying mechanisms and caution must be exercised before similar attempts are undertaken in female Rett patients.
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Affiliation(s)
- Valerie Matagne
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385 Marseille, France
| | - Emilie Borloz
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385 Marseille, France
| | - Yann Ehinger
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385 Marseille, France
| | - Lydia Saidi
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385 Marseille, France
| | - Laurent Villard
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385 Marseille, France
| | - Jean-Christophe Roux
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385 Marseille, France.
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Self-Complementary AAV9 Gene Delivery Partially Corrects Pathology Associated with Juvenile Neuronal Ceroid Lipofuscinosis (CLN3). J Neurosci 2017; 36:9669-82. [PMID: 27629717 DOI: 10.1523/jneurosci.1635-16.2016] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 07/29/2016] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Juvenile neuronal ceroid lipofuscinosis (JNCL) is a fatal lysosomal storage disease caused by autosomal-recessive mutations in CLN3 for which no treatment exists. Symptoms appear between 5 and 10 years of age, beginning with blindness and seizures, followed by progressive cognitive and motor decline and premature death (late teens to 20s). We explored a gene delivery approach for JNCL by generating two self-complementary adeno-associated virus 9 (scAAV9) constructs to address CLN3 dosage effects using the methyl-CpG-binding protein 2 (MeCP2) and β-actin promoters to drive low versus high transgene expression, respectively. This approach was based on the expectation that low CLN3 levels are required for cellular homeostasis due to minimal CLN3 expression postnatally, although this had not yet been demonstrated in vivo One-month-old Cln3(Δex7/8) mice received one systemic (intravenous) injection of scAAV9/MeCP2-hCLN3 or scAAV9/β-actin-hCLN3, with green fluorescent protein (GFP)-expressing viruses as controls. A promoter-dosage effect was observed in all brain regions examined, in which hCLN3 levels were elevated 3- to 8-fold in Cln3(Δex7/8) mice receiving scAAV9/β-actin-hCLN3 versus scAAV9/MeCP2-hCLN3. However, a disconnect occurred between CLN3 levels and disease improvement, because only the scAAV9 construct driving low CLN3 expression (scAAV9/MeCP2-hCLN3) corrected motor deficits and attenuated microglial and astrocyte activation and lysosomal pathology. This may have resulted from preferential promoter usage because transgene expression after intravenous scAAV9/MeCP2-GFP injection was primarily detected in NeuN(+) neurons, whereas scAAV9/β-actin-GFP drove transgene expression in GFAP(+) astrocytes. This is the first demonstration of a systemic delivery route to restore CLN3 in vivo using scAAV9 and highlights the importance of promoter selection for disease modification in juvenile animals. SIGNIFICANCE STATEMENT Juvenile neuronal ceroid lipofuscinosis (JNCL) is a fatal lysosomal storage disease caused by CLN3 mutations. We explored a gene delivery approach using two self-complementary adeno-associated virus 9 (scAAV9) constructs to address CLN3 dosage effects using the methyl-CpG-binding protein 2 (MeCP2) and β-actin promoters. hCLN3 levels were elevated 3- to 8-fold in Cln3(Δex7/8) mice receiving scAAV9/β-actin-hCLN3 versus scAAV9/MeCP2-hCLN3 after a single systemic injection. However, only scAAV9/MeCP2-hCLN3 corrected motor deficits and attenuated glial activation and lysosomal pathology. This may reflect preferential promoter usage because transgene expression with scAAV9/MeCP2-green fluorescent protein (GFP) was primarily in neurons, whereas scAAV9/β-actin-GFP drove transgene expression in astrocytes. This is the first demonstration of systemic delivery for CLN3 using scAAV9 and highlights the importance of promoter selection for disease modification in juvenile animals.
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Gadalla KK, Vudhironarit T, Hector RD, Sinnett S, Bahey NG, Bailey ME, Gray SJ, Cobb SR. Development of a Novel AAV Gene Therapy Cassette with Improved Safety Features and Efficacy in a Mouse Model of Rett Syndrome. Mol Ther Methods Clin Dev 2017; 5:180-190. [PMID: 28497075 PMCID: PMC5423329 DOI: 10.1016/j.omtm.2017.04.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 04/19/2017] [Indexed: 12/21/2022]
Abstract
Rett syndrome (RTT), caused by loss-of-function mutations in the MECP2 gene, is a neurological disorder characterized by severe impairment of motor and cognitive functions. The aim of this study was to investigate the impact of vector design, dosage, and delivery route on the efficacy and safety of gene augmentation therapy in mouse models of RTT. Our results show that AAV-mediated delivery of MECP2 to Mecp2 null mice by systemic administration, and utilizing a minimal endogenous promoter, was associated with a narrow therapeutic window and resulted in liver toxicity at higher doses. Lower doses of this vector significantly extended the survival of mice lacking MeCP2 or expressing a mutant T158M allele but had no impact on RTT-like neurological phenotypes. Modifying vector design by incorporating an extended Mecp2 promoter and additional regulatory 3' UTR elements significantly reduced hepatic toxicity after systemic administration. Moreover, direct cerebroventricular injection of this vector into neonatal Mecp2-null mice resulted in high brain transduction efficiency, increased survival and body weight, and an amelioration of RTT-like phenotypes. Our results show that controlling levels of MeCP2 expression in the liver is achievable through modification of the expression cassette. However, it also highlights the importance of achieving high brain transduction to impact the RTT-like phenotypes.
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Affiliation(s)
- Kamal K.E. Gadalla
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Pharmacology Department, Faculty of Medicine, Tanta University, Tanta 31527, Egypt
| | - Thishnapha Vudhironarit
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ralph D. Hector
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sarah Sinnett
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Noha G. Bahey
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Histology Department, Faculty of Medicine, Tanta University, Tanta 31527, Egypt
| | - Mark E.S. Bailey
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Steven J. Gray
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Stuart R. Cobb
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Kwon DY, Zhao YT, Lamonica JM, Zhou Z. Locus-specific histone deacetylation using a synthetic CRISPR-Cas9-based HDAC. Nat Commun 2017; 8:15315. [PMID: 28497787 PMCID: PMC5437308 DOI: 10.1038/ncomms15315] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 03/20/2017] [Indexed: 12/26/2022] Open
Abstract
Efforts to manipulate locus-specific histone acetylation to assess their causal role in gene expression and cellular and behavioural phenotypes have been impeded by a lack of experimental tools. The Cas9 nuclease has been adapted to target epigenomic modifications, but a detailed description of the parameters of such synthetic epigenome remodellers is still lacking. Here we describe a Cas9-based histone deacetylase (HDAC) and the design principles required to achieve locus-specific histone deacetylation. We assess its range of activity and specificity, and analyse target gene expression in two different cell types to investigate cellular context-dependent effects. Our findings demonstrate that the chromatin environment is an important element to consider when utilizing this synthetic HDAC. CRISPR-Cas9 has been utilized, through the fusion of catalytic dead nuclease with chromatin-remodellers, to modify the epigenetic state of specific loci. Here the authors manipulate locus-specific histone acetylation and describe the parameters that need to be considered for its use.
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Affiliation(s)
- Deborah Y Kwon
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Ying-Tao Zhao
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Janine M Lamonica
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Zhaolan Zhou
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Matagne V, Ehinger Y, Saidi L, Borges-Correia A, Barkats M, Bartoli M, Villard L, Roux JC. A codon-optimized Mecp2 transgene corrects breathing deficits and improves survival in a mouse model of Rett syndrome. Neurobiol Dis 2016; 99:1-11. [PMID: 27974239 DOI: 10.1016/j.nbd.2016.12.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/07/2016] [Accepted: 12/09/2016] [Indexed: 11/15/2022] Open
Abstract
Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder that is primarily caused by mutations in the methyl CpG binding protein 2 gene (MECP2). RTT is the second most prevalent cause of intellectual disability in girls and there is currently no cure for the disease. The finding that the deficits caused by the loss of Mecp2 are reversible in the mouse has bolstered interest in gene therapy as a cure for RTT. In order to assess the feasibility of gene therapy in a RTT mouse model, and in keeping with translational goals, we investigated the efficacy of a self-complementary AAV9 vector expressing a codon-optimized version of Mecp2 (AAV9-MCO) delivered via a systemic approach in early symptomatic Mecp2-deficient (KO) mice. Our results show that AAV9-MCO administered at a dose of 2×1011 viral genome (vg)/mouse was able to significantly increase survival and weight gain, and delay the occurrence of behavioral deficits. Apneas, which are one of the core RTT breathing deficits, were significantly decreased to WT levels in Mecp2 KO mice after AAV9-MCO administration. Semi-quantitative analysis showed that AAV9-MCO administration in Mecp2 KO mice resulted in 10 to 20% Mecp2 immunopositive cells compared to WT animals, with the highest Mecp2 expression found in midbrain regions known to regulate cardio-respiratory functions. In addition, we also found a cell autonomous increase in tyrosine hydroxylase levels in the A1C1 and A2C2 catecholaminergic Mecp2+ neurons in treated Mecp2 KO mice, which may partly explain the beneficial effect of AAV9-MCO administration on apneas occurrence.
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Affiliation(s)
- Valerie Matagne
- Aix Marseille Univ, INSERM, GMGF, UMR_S 910, 13385 Marseille, France
| | - Yann Ehinger
- Aix Marseille Univ, INSERM, GMGF, UMR_S 910, 13385 Marseille, France
| | - Lydia Saidi
- Aix Marseille Univ, INSERM, GMGF, UMR_S 910, 13385 Marseille, France
| | | | - Martine Barkats
- Center of Research on Myology, FRE 3617 Centre National de la Recherche Scientifique, UMRS 974 INSERM, French Institute of Myology, Pierre and Marie Curie University Paris, France
| | - Marc Bartoli
- Aix Marseille Univ, INSERM, GMGF, UMR_S 910, 13385 Marseille, France
| | - Laurent Villard
- Aix Marseille Univ, INSERM, GMGF, UMR_S 910, 13385 Marseille, France
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Gadalla KKE, Ross PD, Hector RD, Bahey NG, Bailey MES, Cobb SR. Gene therapy for Rett syndrome: prospects and challenges. FUTURE NEUROLOGY 2015. [DOI: 10.2217/fnl.15.29] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rett syndrome (RTT) is a neurological disorder that affects females and is caused by loss-of-function mutations in the X-linked gene MECP2. Deletion of Mecp2 in mice results in a constellation of neurological features that resemble those seen in RTT patients. Experiments in mice have demonstrated that restoration of MeCP2, even at adult stages, reverses several aspects of the RTT-like pathology suggesting that the disorder may be inherently treatable. This has provided an impetus to explore several therapeutic approaches targeting RTT at the level of the gene, including gene therapy, activation of MECP2 on the inactive X chromosome and read-through and repair of RTT-causing mutations. Here, we review these different strategies and the challenges of gene-based approaches in RTT.
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Affiliation(s)
- Kamal KE Gadalla
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
- Pharmacology Department, Faculty of Medicine, Tanta University, Egypt
| | - Paul D Ross
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
| | - Ralph D Hector
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
| | - Noha G Bahey
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
- Histology Department, Faculty of Medicine, Tanta University, Egypt
| | - Mark ES Bailey
- School of Life Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Stuart R Cobb
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
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12
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Maguire CA, Ramirez SH, Merkel SF, Sena-Esteves M, Breakefield XO. Gene therapy for the nervous system: challenges and new strategies. Neurotherapeutics 2014; 11:817-39. [PMID: 25159276 PMCID: PMC4391389 DOI: 10.1007/s13311-014-0299-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Current clinical treatments for central nervous system (CNS) diseases, such as Parkinson's disease and glioblastoma do not halt disease progression and have significant treatment morbidities. Gene therapy has the potential to "permanently" correct disease by bringing in a normal gene to correct a mutant gene deficiency, knocking down mRNA of mutant alleles, and inducing cell-death in cancer cells using transgenes encoding apoptosis-inducing proteins. Promising results in clinical trials of eye disease (Leber's congenital aumorosis) and Parkinson's disease have shown that gene-based neurotherapeutics have great potential. The recent development of genome editing technology, such as zinc finger nucleases, TALENS, and CRISPR, has made the ultimate goal of gene correction a step closer. This review summarizes the challenges faced by gene-based neurotherapeutics and the current and recent strategies designed to overcome these barriers. We have chosen the following challenges to focus on in this review: (1) delivery vehicles (both virus and nonviral), (2) use of promoters for vector-mediated gene expression in CNS, and (3) delivery across the blood-brain barrier. The final section (4) focuses on promising pre-clinical/clinical studies of neurotherapeutics.
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Affiliation(s)
- Casey A Maguire
- Department of Neurology, Massachusetts General Hospital, and Neuroscience Program, Harvard Medical School, Molecular Neurogenetics Unit, 13th Street, Building 149, Charlestown, MA, 02129, USA,
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Abstract
Rett syndrome (RTT) is a severe and progressive neurological disorder, which mainly affects young females. Mutations of the methyl-CpG binding protein 2 (MECP2) gene are the most prevalent cause of classical RTT cases. MECP2 mutations or altered expression are also associated with a spectrum of neurodevelopmental disorders such as autism spectrum disorders with recent links to fetal alcohol spectrum disorders. Collectively, MeCP2 relation to these neurodevelopmental disorders highlights the importance of understanding the molecular mechanisms by which MeCP2 impacts brain development, mental conditions, and compromised brain function. Since MECP2 mutations were discovered to be the primary cause of RTT, a significant progress has been made in the MeCP2 research, with respect to the expression, function and regulation of MeCP2 in the brain and its contribution in RTT pathogenesis. To date, there have been intensive efforts in designing effective therapeutic strategies for RTT benefiting from mouse models and cells collected from RTT patients. Despite significant progress in MeCP2 research over the last few decades, there is still a knowledge gap between the in vitro and in vivo research findings and translating these findings into effective therapeutic interventions in human RTT patients. In this review, we will provide a synopsis of Rett syndrome as a severe neurological disorder and will discuss the role of MeCP2 in RTT pathophysiology.
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Olson CO, Zachariah RM, Ezeonwuka CD, Liyanage VRB, Rastegar M. Brain region-specific expression of MeCP2 isoforms correlates with DNA methylation within Mecp2 regulatory elements. PLoS One 2014; 9:e90645. [PMID: 24594659 PMCID: PMC3940938 DOI: 10.1371/journal.pone.0090645] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 02/05/2014] [Indexed: 01/08/2023] Open
Abstract
MeCP2 is a critical epigenetic regulator in brain and its abnormal expression or compromised function leads to a spectrum of neurological disorders including Rett Syndrome and autism. Altered expression of the two MeCP2 isoforms, MeCP2E1 and MeCP2E2 has been implicated in neurological complications. However, expression, regulation and functions of the two isoforms are largely uncharacterized. Previously, we showed the role of MeCP2E1 in neuronal maturation and reported MeCP2E1 as the major protein isoform in the adult mouse brain, embryonic neurons and astrocytes. Recently, we showed that DNA methylation at the regulatory elements (REs) within the Mecp2 promoter and intron 1 impact the expression of Mecp2 isoforms in differentiating neural stem cells. This current study is aimed for a comparative analysis of temporal, regional and cell type-specific expression of MeCP2 isoforms in the developing and adult mouse brain. MeCP2E2 displayed a later expression onset than MeCP2E1 during mouse brain development. In the adult female and male brain hippocampus, both MeCP2 isoforms were detected in neurons, astrocytes and oligodendrocytes. Furthermore, MeCP2E1 expression was relatively uniform in different brain regions (olfactory bulb, striatum, cortex, hippocampus, thalamus, brainstem and cerebellum), whereas MeCP2E2 showed differential enrichment in these brain regions. Both MeCP2 isoforms showed relatively similar distribution in these brain regions, except for cerebellum. Lastly, a preferential correlation was observed between DNA methylation at specific CpG dinucleotides within the REs and Mecp2 isoform-specific expression in these brain regions. Taken together, we show that MeCP2 isoforms display differential expression patterns during brain development and in adult mouse brain regions. DNA methylation patterns at the Mecp2 REs may impact this differential expression of Mecp2/MeCP2 isoforms in brain regions. Our results significantly contribute towards characterizing the expression profiles of Mecp2/MeCP2 isoforms and thereby provide insights on the potential role of MeCP2 isoforms in the developing and adult brain.
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Affiliation(s)
- Carl O. Olson
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Robby M. Zachariah
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Chinelo D. Ezeonwuka
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Vichithra R. B. Liyanage
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Mojgan Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Liyanage VRB, Zachariah RM, Rastegar M. Decitabine alters the expression of Mecp2 isoforms via dynamic DNA methylation at the Mecp2 regulatory elements in neural stem cells. Mol Autism 2013; 4:46. [PMID: 24238559 PMCID: PMC3900258 DOI: 10.1186/2040-2392-4-46] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 10/01/2013] [Indexed: 01/01/2023] Open
Abstract
Background Aberrant MeCP2 expression in brain is associated with neurodevelopmental disorders including autism. In the brain of stressed mouse and autistic human patients, reduced MeCP2 expression is correlated with Mecp2/MECP2 promoter hypermethylation. Altered expression of MeCP2 isoforms (MeCP2E1 and MeCP2E2) is associated with neurological disorders, highlighting the importance of proper regulation of both isoforms. While known regulatory elements (REs) within the MECP2/Mecp2 promoter and intron 1 are involved in MECP2/Mecp2 regulation, Mecp2 isoform-specific regulatory mechanisms are unknown. We hypothesized that DNA methylation at these REs may impact the expression of Mecp2 isoforms. Methods We used a previously characterized in vitro differentiating neural stem cell (NSC) system to investigate the interplay between Mecp2 isoform-specific expression and DNA methylation at the Mecp2 REs. We studied altered expression of Mecp2 isoforms, affected by global DNA demethylation and remethylation, induced by exposure and withdrawal of decitabine (5-Aza-2′-deoxycytidine). Further, we performed correlation analysis between DNA methylation at the Mecp2 REs and the expression of Mecp2 isoforms after decitabine exposure and withdrawal. Results At different stages of NSC differentiation, Mecp2 isoforms showed reciprocal expression patterns associated with minor, but significant changes in DNA methylation at the Mecp2 REs. Decitabine treatment induced Mecp2e1/MeCP2E1 (but not Mecp2e2) expression at day (D) 2, associated with DNA demethylation at the Mecp2 REs. In contrast, decitabine withdrawal downregulated both Mecp2 isoforms to different extents at D8, without affecting DNA methylation at the Mecp2 REs. NSC cell fate commitment was minimally affected by decitabine under tested conditions. Expression of both isoforms negatively correlated with methylation at specific regions of the Mecp2 promoter, both at D2 and D8. The correlation between intron 1 methylation and Mecp2e1 (but not Mecp2e2) varied depending on the stage of NSC differentiation (D2: negative; D8: positive). Conclusions Our results show the correlation between the expression of Mecp2 isoforms and DNA methylation in differentiating NSC, providing insights on the potential role of DNA methylation at the Mecp2 REs in Mecp2 isoform-specific expression. The ability of decitabine to induce Mecp2e1/MeCP2E1, but not Mecp2e2 suggests differential sensitivity of Mecp2 isoforms to decitabine and is important for future drug therapies for autism.
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Affiliation(s)
| | | | - Mojgan Rastegar
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Rm, 627, Basic Medical Sciences Bldg,, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada.
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Zachariah RM, Olson CO, Ezeonwuka C, Rastegar M. Novel MeCP2 isoform-specific antibody reveals the endogenous MeCP2E1 expression in murine brain, primary neurons and astrocytes. PLoS One 2012. [PMID: 23185431 PMCID: PMC3501454 DOI: 10.1371/journal.pone.0049763] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Rett Syndrome (RTT) is a severe neurological disorder in young females, and is caused by mutations in the X-linked MECP2 gene. MECP2/Mecp2 gene encodes for two protein isoforms; MeCP2E1 and MeCP2E2 that are identical except for the N-terminus region of the protein. In brain, MECP2E1 transcripts are 10X higher, and MeCP2E1 is suggested to be the relevant isoform for RTT. However, due to the unavailability of MeCP2 isoform-specific antibodies, the endogenous expression pattern of MeCP2E1 is unknown. To gain insight into the expression of MeCP2E1 in brain, we have developed an anti-MeCP2E1 antibody and validated its specificity in cells exogenously expressing individual MeCP2 isoforms. This antibody does not show any cross-reactivity with MeCP2E2 and detects endogenous MeCP2E1 in mice brain, with no signal in Mecp2tm1.1Bird y/− null mice. Additionally, we show the endogenous MeCP2E1 expression throughout different brain regions in adult mice, and demonstrate its highest expression in the brain cortex. Our results also indicate that MeCP2E1 is highly expressed in primary neurons, as compared to primary astrocytes. This is the first report of the endogenous MeCP2E1 expression at the protein levels, providing novel avenues for understanding different aspects of MeCP2 function.
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Affiliation(s)
- Robby M. Zachariah
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Carl O. Olson
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Chinelo Ezeonwuka
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Mojgan Rastegar
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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17
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Gray SJ. Gene therapy and neurodevelopmental disorders. Neuropharmacology 2012; 68:136-42. [PMID: 22750077 DOI: 10.1016/j.neuropharm.2012.06.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 06/11/2012] [Accepted: 06/13/2012] [Indexed: 02/06/2023]
Abstract
With a number of recent clinical successes, gene therapy is quickly becoming a realistic treatment option for neurological disorders. Advancements in global central nervous system (CNS) gene delivery, in particular, have accelerated to the point that treatments for neurological disorders such as lysosomal storage diseases seem within reach. Other neurodevelopmental disorders, such as Rett Syndrome, Fragile X, and autism still face significant obstacles to overcome before a viable human gene therapy can be considered. This review focuses on the most common CNS gene delivery vehicle, adeno-associated virus (AAV), and the current state of AAV vector design and delivery for CNS gene therapy. Relevant examples of gene therapy studies for neurodevelopmental disorders, as well as outstanding challenges, are discussed. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Steven James Gray
- Gene Therapy Center, University of North Carolina at Chapel Hill, 7109 Thurston Bowles, 104 Manning Drive, Chapel Hill, NC 27599-7352, USA.
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Yasui DH, Scoles HA, Horike SI, Meguro-Horike M, Dunaway KW, Schroeder DI, Lasalle JM. 15q11.2-13.3 chromatin analysis reveals epigenetic regulation of CHRNA7 with deficiencies in Rett and autism brain. Hum Mol Genet 2011; 20:4311-23. [PMID: 21840925 DOI: 10.1093/hmg/ddr357] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Copy number variations (CNVs) within human 15q11.2-13.3 show reduced penetrance and variable expressivity in a range of neurologic disorders. Therefore, characterizing 15q11.2-13.3 chromatin structure is important for understanding the regulation of this locus during normal neuronal development. Deletion of the Prader-Willi imprinting center (PWS-IC) within 15q11.2-13.3 disrupts long-range imprinted gene expression resulting in Prader-Willi syndrome. Previous results establish that MeCP2 binds to the PWS-IC and is required for optimal expression of distal GABRB3 and UBE3A. To examine the hypothesis that MeCP2 facilitates 15q11.2-13.3 transcription by linking the PWS-IC with distant elements, chromosome capture conformation on chip (4C) analysis was performed in human SH-SY5Y neuroblastoma cells. SH-SY5Y neurons had 2.84-fold fewer 15q11.2-13.3 PWS-IC chromatin interactions than undifferentiated SH-SY5Y neuroblasts, revealing developmental chromatin de-condensation of the locus. Out of 68 PWS-IC interactions with15q11.2-13.3 identified by 4C analysis and 62 15q11.2-13.3 MeCP2-binding sites identified by previous ChIP-chip studies, only five sites showed overlap. Remarkably, two of these overlapping PWS-IC- and MeCP2-bound sites mapped to sites flanking CHRNA7 (cholinergic receptor nicotinic alpha 7) encoding the cholinergic receptor, nicotinic, alpha 7. PWS-IC interaction with CHRNA7 in neurons was independently confirmed by fluorescent in situ hybridization analysis. Subsequent quantitative transcriptional analyses of frontal cortex from Rett syndrome and autism patients revealed significantly reduced CHRNA7 expression compared with controls. Together, these results suggest that transcription of CHRNA7 is modulated by chromatin interactions with the PWS-IC. Thus, loss of long-range chromatin interactions within 15q11.2-13.3 may contribute to multiple human neurodevelopmental disorders.
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Affiliation(s)
- Dag H Yasui
- Department of Medical Microbiology and Immunology, Genome Center, University of California Davis School of Medicine, One Shields Avenue, Davis, CA 95616, USA.
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Gray SJ, Foti SB, Schwartz JW, Bachaboina L, Taylor-Blake B, Coleman J, Ehlers MD, Zylka MJ, McCown TJ, Samulski RJ. Optimizing promoters for recombinant adeno-associated virus-mediated gene expression in the peripheral and central nervous system using self-complementary vectors. Hum Gene Ther 2011; 22:1143-53. [PMID: 21476867 DOI: 10.1089/hum.2010.245] [Citation(s) in RCA: 277] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
With the increased use of small self-complementary adeno-associated viral (AAV) vectors, the design of compact promoters becomes critical for packaging and expressing larger transgenes under ubiquitous or cell-specific control. In a comparative study of commonly used 800-bp cytomegalovirus (CMV) and chicken β-actin (CBA) promoters, we report significant differences in the patterns of cell-specific gene expression in the central and peripheral nervous systems. The CMV promoter provides high initial neural expression that diminishes over time. The CBA promoter displayed mostly ubiquitous and high neural expression, but substantially lower expression in motor neurons (MNs). We report the creation of a novel hybrid form of the CBA promoter (CBh) that provides robust long-term expression in all cells observed with CMV or CBA, including MNs. To develop a short neuronal promoter to package larger transgenes into AAV vectors, we also found that a 229-bp fragment of the mouse methyl-CpG-binding protein-2 (MeCP2) promoter was able to drive neuron-specific expression within the CNS. Thus the 800-bp CBh promoter provides strong, long-term, and ubiquitous CNS expression whereas the MeCP2 promoter allows an extra 570-bp packaging capacity, with low and mostly neuronal expression within the CNS, similar to the MeCP2 transcription factor.
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Affiliation(s)
- Steven J Gray
- Gene Therapy Center, University of North Carolina, Chapel Hill, NC 27599, USA
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20
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Alvarez-Saavedra M, Carrasco L, Sura-Trueba S, Demarchi Aiello V, Walz K, Neto JX, Young JI. Elevated expression of MeCP2 in cardiac and skeletal tissues is detrimental for normal development. Hum Mol Genet 2010; 19:2177-90. [PMID: 20203171 DOI: 10.1093/hmg/ddq096] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
MeCP2 plays a critical role in interpreting epigenetic signatures that command chromatin conformation and regulation of gene transcription. In spite of MeCP2's ubiquitous expression, its functions have always been considered in the context of brain physiology. In this study, we demonstrate that alterations of the normal pattern of expression of MeCP2 in cardiac and skeletal tissues are detrimental for normal development. Overexpression of MeCP2 in the mouse heart leads to embryonic lethality with cardiac septum hypertrophy and dysregulated expression of MeCP2 in skeletal tissue produces severe malformations. We further show that MeCP2's expression in the heart is developmentally regulated; further suggesting that it plays a key role in regulating transcriptional programs in non-neural tissues.
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MECP2 isoform-specific vectors with regulated expression for Rett syndrome gene therapy. PLoS One 2009; 4:e6810. [PMID: 19710912 PMCID: PMC2728539 DOI: 10.1371/journal.pone.0006810] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Accepted: 07/30/2009] [Indexed: 12/19/2022] Open
Abstract
Background Rett Syndrome (RTT) is an Autism Spectrum Disorder and the leading cause of mental retardation in females. RTT is caused by mutations in the Methyl CpG-Binding Protein-2 (MECP2) gene and has no treatment. Our objective is to develop viral vectors for MECP2 gene transfer into Neural Stem Cells (NSC) and neurons suitable for gene therapy of Rett Syndrome. Methodology/Principal Findings We generated self-inactivating (SIN) retroviral vectors with the ubiquitous EF1α promoter avoiding known silencer elements to escape stem-cell-specific viral silencing. High efficiency NSC infection resulted in long-term EGFP expression in transduced NSC and after differentiation into neurons. Infection with Myc-tagged MECP2-isoform-specific (E1 and E2) vectors directed MeCP2 to heterochromatin of transduced NSC and neurons. In contrast, vectors with an internal mouse Mecp2 promoter (MeP) directed restricted expression only in neurons and glia and not NSC, recapitulating the endogenous expression pattern required to avoid detrimental consequences of MECP2 ectopic expression. In differentiated NSC from adult heterozygous Mecp2tm1.1Bird+/− female mice, 48% of neurons expressed endogenous MeCP2 due to random inactivation of the X-linked Mecp2 gene. Retroviral MECP2 transduction with EF1α and MeP vectors rescued expression in 95–100% of neurons resulting in increased dendrite branching function in vitro. Insulated MECP2 isoform-specific lentiviral vectors show long-term expression in NSC and their differentiated neuronal progeny, and directly infect dissociated murine cortical neurons with high efficiency. Conclusions/Significance MeP vectors recapitulate the endogenous expression pattern of MeCP2 in neurons and glia. They have utility to study MeCP2 isoform-specific functions in vitro, and are effective gene therapy vectors for rescuing dendritic maturation of neurons in an ex vivo model of RTT.
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MeCP2-mediated transcription repression in the basolateral amygdala may underlie heightened anxiety in a mouse model of Rett syndrome. J Neurosci 2009; 29:4218-27. [PMID: 19339616 DOI: 10.1523/jneurosci.4225-08.2009] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Rett syndrome (RTT) is an X-linked neurodevelopmental disorder that results from loss of function mutations in the methyl-CpG binding protein 2 (MECP2) gene. Using viral-mediated basolateral amygdala (BLA)-specific deletion of Mecp2 in mice, we show that intact Mecp2 function is required for normal anxiety behavior as well as some types of learning and memory. To examine whether these behavioral deficits are the result of impaired transcriptional repression, because Mecp2 is believed to act as a transcriptional repressor in complex with histone deacetylases (HDACs), we infused a HDAC inhibitor chronically into the BLA of wild-type mice. We found that HDAC inhibition produces behavioral deficits similar to those observed after the deletion of Mecp2 in the BLA. These results suggest a key role for Mecp2 as a transcriptional repressor in the BLA in mediating behavioral features of RTT.
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Jones FS, Jing J, Stonehouse AH, Stevens A, Edelman GM. Caffeine Stimulates Cytochrome Oxidase Expression and Activity in the Striatum in a Sexually Dimorphic Manner. Mol Pharmacol 2008; 74:673-84. [DOI: 10.1124/mol.108.046888] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Abstract
Recent progress in our understanding of Rett syndrome has been dramatic. Against the background that the clinical features of Rett syndrome may be reversible, in part or in whole, substantial optimism has emerged regarding possible therapies. As such, it is timely to update recent research progress. This update summarizes research advances during the past 18 to 24 months in terms of clinical and translational research, as well as basic research.
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Affiliation(s)
- Alan K Percy
- Department of Pediatrics, University of Alabama at Birmingham, AL 35294-0021, USA.
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25
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Nagarajan RP, Hogart AR, Gwye Y, Martin MR, LaSalle JM. Reduced MeCP2 expression is frequent in autism frontal cortex and correlates with aberrant MECP2 promoter methylation. Epigenetics 2008; 1:e1-11. [PMID: 17486179 PMCID: PMC1866172 DOI: 10.4161/epi.1.4.3514] [Citation(s) in RCA: 246] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mutations in MECP2, encoding methyl CpG binding protein 2 (MeCP2), cause most cases of Rett syndrome (RTT), an X-linked neurodevelopmental disorder. Both RTT and autism are "pervasive developmental disorders" and share a loss of social, cognitive and language skills and a gain in repetitive stereotyped behavior, following apparently normal perinatal development. Although MECP2 coding mutations are a rare cause of autism, MeCP2 expression defects were previously found in autism brain. To further study the role of MeCP2 in autism spectrum disorders (ASDs), we determined the frequency of MeCP2 expression defects in brain samples from autism and other ASDs. We also tested the hypotheses that MECP2 promoter mutations or aberrant promoter methylation correlate with reduced expression in cases of idiopathic autism. MeCP2 immunofluorescence in autism and other neurodevelopmental disorders was quantified by laser scanning cytometry and compared with control postmortem cerebral cortex samples on a large tissue microarray. A significant reduction in MeCP2 expression compared to age-matched controls was found in 11/14 autism (79%), 9/9 RTT (100%), 4/4 Angelman syndrome (100%), 3/4 Prader-Willi syndrome (75%), 3/5 Down syndrome (60%), and 2/2 attention deficit hyperactivity disorder (100%) frontal cortex samples. One autism female was heterozygous for a rare MECP2 promoter variant that correlated with reduced MeCP2 expression. A more frequent occurrence was significantly increased MECP2 promoter methylation in autism male frontal cortex compared to controls. Furthermore, percent promoter methylation of MECP2 significantly correlated with reduced MeCP2 protein expression. These results suggest that both genetic and epigenetic defects lead to reduced MeCP2 expression and may be important in the complex etiology of autism.
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Affiliation(s)
| | | | | | | | - Janine M. LaSalle
- * Address correspondence to: Janine M. LaSalle, Medical Microbiology and Immunology, One Shields Ave., Davis, CA 95616, (530) 754-7598 (phone), (530) 752-8692, (fax)
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Jung BP, Purushotham D, Eubanks JH. Identification of a murine methyl cytosine phosphate guanine binding domain-containing factor 3 (MBD3) promoter segment sufficient for driving reporter gene expression in neurons in vitro and in vivo. Neuroscience 2007; 145:1016-25. [PMID: 17289276 DOI: 10.1016/j.neuroscience.2006.12.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 12/08/2006] [Accepted: 12/27/2006] [Indexed: 10/23/2022]
Abstract
In this study, we characterize the functional properties of a segment of the murine methyl cytosine phosphate guanine binding domain-containing factor 3 (MBD3) promoter region. Transient transfection of a chimera consisting of a 1072 base pair region extending upstream from the MBD3 initiation codon fused to a luciferase complementary DNA (cDNA) confirmed the presence of a functional promoter unit. Primer extension analysis failed to identify a single predominant transcription initiation site, but rather detected multiple transcription initiation sites in both brain tissue and cultured neuroblastomaxglioma cell line (NG108-15) and rat pheochromocytoma cell line (PC12) cells. Reporter gene assays revealed that this 1072 base pair fragment efficiently drives expression in transfected NG108-15 cells, PC12 cells, cultured primary neurons, and in neurons of a transgenic mouse brain. Deletion analysis mapped the critical region for promoter activity to a segment of approximately 518 base pairs, located from positions -585 to -68 relative to the translational start codon. Taken together, these data indicate that a 1072 base pair fragment of the MBD3 promoter is sufficient to drive expression in cell lines and primary cultured neurons, and is able to direct transgene expression in the mouse brain in a pattern with spatial similarity to that of native MBD3.
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Affiliation(s)
- B P Jung
- Division of Cellular and Molecular Biology, Toronto Western Research Institute, Mac 11-412, 399 Bathurst Street, Toronto, Ontario, Canada
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Lugtenberg D, JC Hamel B, van Bokhoven H, PM de Brouwer A. Strategies for present and future mental retardation diagnosis. FUTURE NEUROLOGY 2006. [DOI: 10.2217/14796708.1.6.775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mental retardation (MR) is a highly heterogeneous condition with a prevalence of 1–3% in the general population. The psychosocial burden on families with mentally handicapped children is extensive. In addition, the accompanying expenses with mental handicaps are considerable. In this review a comprehensive strategy to systematically identify the causative genetic defect in patients with mental retardation is proposed. This strategy is a combination of routinely used and recently developed approaches, such as direct DNA sequencing, single nucleotide polymorphism arrays and expression profiling, to establish a molecular diagnosis in MR patients. Finally, it will be described how these mutations can be studied in different model systems, which can eventually be used to elucidate the neurobiological basis of MR and to facilitate possible therapeutic intervention.
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Affiliation(s)
- Dorien Lugtenberg
- Radboud University, Department of Human Genetics, Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Ben JC Hamel
- Radboud University, Department of Human Genetics, Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Hans van Bokhoven
- Radboud University, Department of Human Genetics, Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Arjan PM de Brouwer
- Radboud University, Department of Human Genetics, Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Abstract
Rett syndrome (RTT) is an X-linked dominant disabling neurodevelopmental disorder caused by loss of function mutations in the MECP2 gene, located at Xq28, which encodes a multifunctional protein. MECP2 expression is regulated in a developmental stage and cell-type-specific manner. The need for tightly controlled MeCP2 levels in brain is strongly suggested by neurologically abnormal phenotypes of mouse models with mild overexpression and by mental retardation in human males with MECP2 duplication. We set out to identify long-range cis-regulatory sequences that differentially regulate MECP2 transcription and, when mutated, may contribute to the pathogenesis of RTT, autism or X-linked mental retardation. By inter-species sequence comparisons, we detected 27 highly conserved non-coding DNA sequences within a 210 kb region covering MECP2. We functionally confirmed four enhancer and two silencer elements by performing luciferase reporter assays in four different human cell lines. The transcription factor binding capability of the identified regulatory elements was tested by gel shift assays. To locate the human MECP2 core promoter, we dissected the promoter region by reporter assays with deletion constructs. We then used chromosome conformation capture methods to document long-range interactions of three enhancers and two silencers with the MECP2 promoter. Acting over distances of up to 130 kb, these elements may influence chromatin configurations and regulate MECP2 transcription. Our study has defined the "MECP2 functional expression module" and identified enhancer and silencer elements that are likely to be responsible for the tissue-specific, developmental stage-specific or splice-variant-specific control of MeCP2 protein expression.
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Affiliation(s)
- Jinglan Liu
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
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