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Achilly NP, He LJ, Kim OA, Ohmae S, Wojaczynski GJ, Lin T, Sillitoe RV, Medina JF, Zoghbi HY. Deleting Mecp2 from the cerebellum rather than its neuronal subtypes causes a delay in motor learning in mice. eLife 2021; 10:64833. [PMID: 33494858 PMCID: PMC7837679 DOI: 10.7554/elife.64833] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/13/2021] [Indexed: 12/28/2022] Open
Abstract
Rett syndrome is a devastating childhood neurological disorder caused by mutations in MECP2. Of the many symptoms, motor deterioration is a significant problem for patients. In mice, deleting Mecp2 from the cortex or basal ganglia causes motor dysfunction, hypoactivity, and tremor, which are abnormalities observed in patients. Little is known about the function of Mecp2 in the cerebellum, a brain region critical for motor function. Here we show that deleting Mecp2 from the cerebellum, but not from its neuronal subtypes, causes a delay in motor learning that is overcome by additional training. We observed irregular firing rates of Purkinje cells and altered heterochromatin architecture within the cerebellum of knockout mice. These findings demonstrate that the motor deficits present in Rett syndrome arise, in part, from cerebellar dysfunction. For Rett syndrome and other neurodevelopmental disorders, our results highlight the importance of understanding which brain regions contribute to disease phenotypes.
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Affiliation(s)
- Nathan P Achilly
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Medical Scientist Training Program, Baylor College of Medicine, Houston, United States
| | - Ling-Jie He
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Olivia A Kim
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Shogo Ohmae
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | | | - Tao Lin
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States
| | - Roy V Sillitoe
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States
| | - Javier F Medina
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Huda Y Zoghbi
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Department of Neurology, Baylor College of Medicine, Houston, United States.,Department of Pediatrics, Baylor College of Medicine, Houston, United States
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Sloan JL, Achilly NP, Arnold ML, Catlett JL, Blake T, Bishop K, Jones M, Harper U, English MA, Anderson S, Trivedi NS, Elkahloun A, Hoffmann V, Brooks BP, Sood R, Venditti CP. The vitamin B12 processing enzyme, mmachc, is essential for zebrafish survival, growth and retinal morphology. Hum Mol Genet 2020; 29:2109-2123. [PMID: 32186706 PMCID: PMC7399538 DOI: 10.1093/hmg/ddaa044] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/10/2020] [Accepted: 03/11/2020] [Indexed: 12/16/2022] Open
Abstract
Cobalamin C (cblC) deficiency, the most common inborn error of intracellular cobalamin metabolism, is caused by mutations in MMACHC, a gene responsible for the processing and intracellular trafficking of vitamin B12. This recessive disorder is characterized by a failure to metabolize cobalamin into adenosyl- and methylcobalamin, which results in the biochemical perturbations of methylmalonic acidemia, hyperhomocysteinemia and hypomethioninemia caused by the impaired activity of the downstream enzymes, methylmalonyl-CoA mutase and methionine synthase. Cobalamin C deficiency can be accompanied by a wide spectrum of clinical manifestations, including progressive blindness, and, in mice, manifests with very early embryonic lethality. Because zebrafish harbor a full complement of cobalamin metabolic enzymes, we used genome editing to study the loss of mmachc function and to develop the first viable animal model of cblC deficiency. mmachc mutants survived the embryonic period but perished in early juvenile life. The mutants displayed the metabolic and clinical features of cblC deficiency including methylmalonic acidemia, severe growth retardation and lethality. Morphologic and metabolic parameters improved when the mutants were raised in water supplemented with small molecules used to treat patients, including hydroxocobalamin, methylcobalamin, methionine and betaine. Furthermore, mmachc mutants bred to express rod and/or cone fluorescent reporters, manifested a retinopathy and thin optic nerves (ON). Expression analysis using whole eye mRNA revealed the dysregulation of genes involved in phototransduction and cholesterol metabolism. Zebrafish with mmachc deficiency recapitulate the several of the phenotypic and biochemical features of the human disorder, including ocular pathology, and show a response to established treatments.
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Affiliation(s)
- Jennifer L Sloan
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Nathan P Achilly
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Madeline L Arnold
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Jerrel L Catlett
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Trevor Blake
- Zebrafish Core Facility, Translational and Functional Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Kevin Bishop
- Zebrafish Core Facility, Translational and Functional Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Marypat Jones
- Genomics Core, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Ursula Harper
- Genomics Core, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Milton A English
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, Bethesda, MD, 20892 USA
| | - Stacie Anderson
- Flow Cytometry, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Niraj S Trivedi
- Social Behavioral Research Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Abdel Elkahloun
- Microarray Core, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Victoria Hoffmann
- Diagnostic and Research Services Branch, Division of Veterinary Resources, Office of the Director, National Institutes of Health, Bethesda, MD, 20892 USA
| | - Brian P Brooks
- Office of the Clinical Director, National Eye Institute, Bethesda, MD, 20892 USA
| | - Raman Sood
- Zebrafish Core Facility, Translational and Functional Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Charles P Venditti
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
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Arnold M, Sloan JL, Achilly NP, Elliot G, Onojafe IF, Brooks BP, Venditti CP. 46. The First Viable Mouse Model of cblC Type Combined Methylmalonic Acidemia and Homocysteinemia: AAV Gene Therapy Rescues Neonatal Lethality and Provides Insight into Disease-Associated Retinal Degeneration. Mol Ther 2016. [DOI: 10.1016/s1525-0016(16)32855-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Achilly NP. Properties of VIP+ synapses in the suprachiasmatic nucleus highlight their role in circadian rhythm. J Neurophysiol 2015; 115:2701-4. [PMID: 26581865 DOI: 10.1152/jn.00393.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 11/17/2015] [Indexed: 01/19/2023] Open
Abstract
Circadian rhythms coordinate cyclical behavioral and physiological changes in most organisms. In humans, this biological clock is located within the suprachiasmatic nucleus (SCN) of the hypothalamus and consists of a heterogeneous neuron population characterized by their enriched expression of various neuropeptides. As highlighted here, Fan et al. (J Neurosci 35: 1905-1029, 2015) developed an elegant experimental system to investigate the synaptic properties of vasoactive intestinal peptide (VIP)-expressing neurons between day and night, and further delineate their broader architecture and function within the SCN.
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Affiliation(s)
- Nathan P Achilly
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas
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Yu HC, Sloan JL, Scharer G, Brebner A, Quintana AM, Achilly NP, Manoli I, Coughlin CR, Geiger EA, Schneck U, Watkins D, Suormala T, Van Hove JLK, Fowler B, Baumgartner MR, Rosenblatt DS, Venditti CP, Shaikh TH. An X-linked cobalamin disorder caused by mutations in transcriptional coregulator HCFC1. Am J Hum Genet 2013; 93:506-14. [PMID: 24011988 DOI: 10.1016/j.ajhg.2013.07.022] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/09/2013] [Accepted: 07/26/2013] [Indexed: 12/31/2022] Open
Abstract
Derivatives of vitamin B12 (cobalamin) are essential cofactors for enzymes required in intermediary metabolism. Defects in cobalamin metabolism lead to disorders characterized by the accumulation of methylmalonic acid and/or homocysteine in blood and urine. The most common inborn error of cobalamin metabolism, combined methylmalonic acidemia and hyperhomocysteinemia, cblC type, is caused by mutations in MMACHC. However, several individuals with presumed cblC based on cellular and biochemical analysis do not have mutations in MMACHC. We used exome sequencing to identify the genetic basis of an X-linked form of combined methylmalonic acidemia and hyperhomocysteinemia, designated cblX. A missense mutation in a global transcriptional coregulator, HCFC1, was identified in the index case. Additional male subjects were ascertained through two international diagnostic laboratories, and 13/17 had one of five distinct missense mutations affecting three highly conserved amino acids within the HCFC1 kelch domain. A common phenotype of severe neurological symptoms including intractable epilepsy and profound neurocognitive impairment, along with variable biochemical manifestations, was observed in all affected subjects compared to individuals with early-onset cblC. The severe reduction in MMACHC mRNA and protein within subject fibroblast lines suggested a role for HCFC1 in transcriptional regulation of MMACHC, which was further supported by the identification of consensus HCFC1 binding sites in MMACHC. Furthermore, siRNA-mediated knockdown of HCFC1 expression resulted in the coordinate downregulation of MMACHC mRNA. This X-linked disorder demonstrates a distinct disease mechanism by which transcriptional dysregulation leads to an inborn error of metabolism with a complex clinical phenotype.
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Affiliation(s)
- Hung-Chun Yu
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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Puffenberger EG, Jinks RN, Sougnez C, Cibulskis K, Willert RA, Achilly NP, Cassidy RP, Fiorentini CJ, Heiken KF, Lawrence JJ, Mahoney MH, Miller CJ, Nair DT, Politi KA, Worcester KN, Setton RA, Dipiazza R, Sherman EA, Eastman JT, Francklyn C, Robey-Bond S, Rider NL, Gabriel S, Morton DH, Strauss KA. Genetic mapping and exome sequencing identify variants associated with five novel diseases. PLoS One 2012; 7:e28936. [PMID: 22279524 PMCID: PMC3260153 DOI: 10.1371/journal.pone.0028936] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 11/17/2011] [Indexed: 01/12/2023] Open
Abstract
The Clinic for Special Children (CSC) has integrated biochemical and molecular methods into a rural pediatric practice serving Old Order Amish and Mennonite (Plain) children. Among the Plain people, we have used single nucleotide polymorphism (SNP) microarrays to genetically map recessive disorders to large autozygous haplotype blocks (mean = 4.4 Mb) that contain many genes (mean = 79). For some, uninformative mapping or large gene lists preclude disease-gene identification by Sanger sequencing. Seven such conditions were selected for exome sequencing at the Broad Institute; all had been previously mapped at the CSC using low density SNP microarrays coupled with autozygosity and linkage analyses. Using between 1 and 5 patient samples per disorder, we identified sequence variants in the known disease-causing genes SLC6A3 and FLVCR1, and present evidence to strongly support the pathogenicity of variants identified in TUBGCP6, BRAT1, SNIP1, CRADD, and HARS. Our results reveal the power of coupling new genotyping technologies to population-specific genetic knowledge and robust clinical data.
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Affiliation(s)
- Erik G Puffenberger
- Clinic for Special Children, Strasburg, Pennsylvania, United States of America.
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