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Nitschke S, Sullivan MA, Mitra S, Marchioni C, Lee JP Y, Smith BH, Ahonen S, Wu J, Chown E, Wang P, Petković S, Zhao X, DiGiovanni LF, Perri AM, Israelian L, Grossman TR, Kordasiewicz H, Vilaplana F, Iwai K, Nitschke F, Minassian BA. Glycogen synthase downregulation rescues the amylopectinosis of murine RBCK1 deficiency. Brain 2022; 145:2361-2377. [PMID: 35084461 PMCID: PMC9612801 DOI: 10.1093/brain/awac017] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/17/2021] [Accepted: 01/09/2022] [Indexed: 12/06/2023] Open
Abstract
Longer glucan chains tend to precipitate. Glycogen, by far the largest mammalian glucan and the largest molecule in the cytosol with up to 55 000 glucoses, does not, due to a highly regularly branched spherical structure that allows it to be perfused with cytosol. Aberrant construction of glycogen leads it to precipitate, accumulate into polyglucosan bodies that resemble plant starch amylopectin and cause disease. This pathology, amylopectinosis, is caused by mutations in a series of single genes whose functions are under active study toward understanding the mechanisms of proper glycogen construction. Concurrently, we are characterizing the physicochemical particularities of glycogen and polyglucosans associated with each gene. These genes include GBE1, EPM2A and EPM2B, which respectively encode the glycogen branching enzyme, the glycogen phosphatase laforin and the laforin-interacting E3 ubiquitin ligase malin, for which an unequivocal function is not yet known. Mutations in GBE1 cause a motor neuron disease (adult polyglucosan body disease), and mutations in EPM2A or EPM2B a fatal progressive myoclonus epilepsy (Lafora disease). RBCK1 deficiency causes an amylopectinosis with fatal skeletal and cardiac myopathy (polyglucosan body myopathy 1, OMIM# 615895). RBCK1 is a component of the linear ubiquitin chain assembly complex, with unique functions including generating linear ubiquitin chains and ubiquitinating hydroxyl (versus canonical amine) residues, including of glycogen. In a mouse model we now show (i) that the amylopectinosis of RBCK1 deficiency, like in adult polyglucosan body disease and Lafora disease, affects the brain; (ii) that RBCK1 deficiency glycogen, like in adult polyglucosan body disease and Lafora disease, has overlong branches; (iii) that unlike adult polyglucosan body disease but like Lafora disease, RBCK1 deficiency glycogen is hyperphosphorylated; and finally (iv) that unlike laforin-deficient Lafora disease but like malin-deficient Lafora disease, RBCK1 deficiency's glycogen hyperphosphorylation is limited to precipitated polyglucosans. In summary, the fundamental glycogen pathology of RBCK1 deficiency recapitulates that of malin-deficient Lafora disease. Additionally, we uncover sex and genetic background effects in RBCK1 deficiency on organ- and brain-region specific amylopectinoses, and in the brain on consequent neuroinflammation and behavioural deficits. Finally, we exploit the portion of the basic glycogen pathology that is common to adult polyglucosan body disease, both forms of Lafora disease and RBCK1 deficiency, namely overlong branches, to show that a unified approach based on downregulating glycogen synthase, the enzyme that elongates glycogen branches, can rescue all four diseases.
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Affiliation(s)
- Silvia Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mitchell A Sullivan
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
- Glycation and Diabetes Complications, Mater Research Institute–The University of Queensland, Translational Research Institute, Brisbane, QLD, 4102, Australia
| | - Sharmistha Mitra
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Charlotte R Marchioni
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jennifer P Y Lee
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Brandon H Smith
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Saija Ahonen
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Jun Wu
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Erin E Chown
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Peixiang Wang
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Sara Petković
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Laura F DiGiovanni
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Lori Israelian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Tamar R Grossman
- Department of Antisense Drug Discovery, Ionis Pharmaceuticals, Carlsbad, California, USA
| | - Holly Kordasiewicz
- Department of Antisense Drug Discovery, Ionis Pharmaceuticals, Carlsbad, California, USA
| | - Francisco Vilaplana
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm 10691, Sweden
| | - Kazuhiro Iwai
- Department of Molecular and Cellular Physiology, Kyoto University School of Medicine, Kyoto 606-8501, Japan
| | - Felix Nitschke
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Berge A Minassian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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2
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Nitschke S, Chown EE, Zhao X, Gabrielian S, Petković S, Guisso DR, Perri AM, Wang P, Ahonen S, Nitschke F, Minassian BA. An inducible glycogen synthase-1 knockout halts but does not reverse Lafora disease progression in mice. J Biol Chem 2020; 296:100150. [PMID: 33277363 PMCID: PMC7857511 DOI: 10.1074/jbc.ra120.015773] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [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: 08/26/2020] [Revised: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 12/21/2022] Open
Abstract
Malstructured glycogen accumulates over time in Lafora disease (LD) and precipitates into Lafora bodies (LBs), leading to neurodegeneration and intractable fatal epilepsy. Constitutive reduction of glycogen synthase-1 (GYS1) activity prevents murine LD, but the effect of GYS1 reduction later in disease course is unknown. Our goal was to knock out Gys1 in laforin (Epm2a)-deficient LD mice after disease onset to determine whether LD can be halted in midcourse, or even reversed. We generated Epm2a-deficient LD mice with tamoxifen-inducible Cre-mediated Gys1 knockout. Tamoxifen was administered at 4 months and disease progression assessed at 12 months. We verified successful knockout at mRNA and protein levels using droplet digital PCR and Western blots. Glycogen determination and periodic acid-Schiff-diastase staining were used to analyze glycogen and LB accumulation. Immunohistochemistry using astrocytic (glial fibrillary acidic protein) and microglial (ionized calcium-binding adapter molecule 1) markers was performed to investigate neuroinflammation. In the disease-relevant organ, the brain, Gys1 mRNA levels were reduced by 85% and GYS1 protein depleted. Glycogen accumulation was halted at the 4-month level, while LB formation and neuroinflammation were significantly, though incompletely, prevented. Skeletal muscle analysis confirmed that Gys1 knockout inhibits glycogen and LB accumulation. However, tamoxifen-independent Cre recombination precluded determination of disease halting or reversal in this tissue. Our study shows that Gys1 knockdown is a powerful means to prevent LD progression, but this approach did not reduce brain glycogen or LBs to levels below those at the time of intervention. These data suggest that endogenous mechanisms to clear brain LBs are absent or, possibly, compromised in laforin-deficient murine LD.
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Affiliation(s)
- Silvia Nitschke
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Erin E Chown
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Shoghig Gabrielian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Sara Petković
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Dikran R Guisso
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ami M Perri
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Peixiang Wang
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Saija Ahonen
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Felix Nitschke
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
| | - Berge A Minassian
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.
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Chown EE, Wang P, Zhao X, Crowder JJ, Strober JW, Sullivan MA, Xue Y, Bennett CS, Perri AM, Evers BM, Roach PJ, Depaoli‐Roach AA, Akman HO, Pederson BA, Minassian BA. GYS1 or PPP1R3C deficiency rescues murine adult polyglucosan body disease. Ann Clin Transl Neurol 2020; 7:2186-2198. [PMID: 33034425 PMCID: PMC7664254 DOI: 10.1002/acn3.51211] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [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: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Adult polyglucosan body disease (APBD) is an adult-onset neurological variant of glycogen storage disease type IV. APBD is caused by recessive mutations in the glycogen branching enzyme gene, and the consequent accumulation of poorly branched glycogen aggregates called polyglucosan bodies in the nervous system. There are presently no treatments for APBD. Here, we test whether downregulation of glycogen synthesis is therapeutic in a mouse model of the disease. METHODS We characterized the effects of knocking out two pro-glycogenic proteins in an APBD mouse model. APBD mice were crossed with mice deficient in glycogen synthase (GYS1), or mice deficient in protein phosphatase 1 regulatory subunit 3C (PPP1R3C), a protein involved in the activation of GYS1. Phenotypic and histological parameters were analyzed and glycogen was quantified. RESULTS APBD mice deficient in GYS1 or PPP1R3C demonstrated improvements in life span, morphology, and behavioral assays of neuromuscular function. Histological analysis revealed a reduction in polyglucosan body accumulation and of astro- and micro-gliosis in the brains of GYS1- and PPP1R3C-deficient APBD mice. Brain glycogen quantification confirmed the reduction in abnormal glycogen accumulation. Analysis of skeletal muscle, heart, and liver found that GYS1 deficiency reduced polyglucosan body accumulation in all three tissues and PPP1R3C knockout reduced skeletal muscle polyglucosan bodies. INTERPRETATION GYS1 and PPP1R3C are effective therapeutic targets in the APBD mouse model. These findings represent a critical step toward the development of a treatment for APBD and potentially other glycogen storage disease type IV patients.
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Affiliation(s)
- Erin E. Chown
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
- Institute of Medical ScienceUniversity of TorontoTorontoOntarioCanada
| | - Peixiang Wang
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
| | - Xiaochu Zhao
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
| | - Justin J. Crowder
- Indiana University School of Medicine‐MuncieBall State UniversityMuncieIndianaUSA
| | - Jordan W. Strober
- Indiana University School of Medicine‐MuncieBall State UniversityMuncieIndianaUSA
| | - Mitchell A. Sullivan
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
- Glycation and DiabetesMater Research Institute‐University of QueenslandTranslational Research InstituteBrisbaneQueenslandAustralia
| | - Yunlin Xue
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
| | - Cody S. Bennett
- Indiana University School of Medicine‐MuncieBall State UniversityMuncieIndianaUSA
| | - Ami M. Perri
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
| | - Bret M. Evers
- Department of PathologyUniversity of Texas SouthwesternDallasTexasUSA
| | - Peter J. Roach
- Department of Biochemistry and Molecular BiologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Anna A. Depaoli‐Roach
- Department of Biochemistry and Molecular BiologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - H. Orhan Akman
- Department of NeurologyH. Houston Merritt Neuromuscular Research CenterColumbia University Medical CenterNew YorkNew YorkUSA
| | | | - Berge A. Minassian
- Genetics and Genome Biology ProgramThe Hospital for Sick ChildrenPeter Gilgan Centre for Research and LearningTorontoOntarioCanada
- Division of NeurologyDepartment of PediatricsUniversity of Texas SouthwesternDallasTexasUSA
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4
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Israelian L, Nitschke S, Wang P, Zhao X, Perri AM, Lee JPY, Verhalen B, Nitschke F, Minassian BA. Ppp1r3d deficiency preferentially inhibits neuronal and cardiac Lafora body formation in a mouse model of the fatal epilepsy Lafora disease. J Neurochem 2020; 157:1897-1910. [PMID: 32892347 DOI: 10.1111/jnc.15176] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 08/27/2020] [Accepted: 08/31/2020] [Indexed: 12/20/2022]
Abstract
Mammalian glycogen chain lengths are subject to complex regulation, including by seven proteins (protein phosphatase-1 regulatory subunit 3, PPP1R3A through PPP1R3G) that target protein phosphatase-1 (PP1) to glycogen to activate the glycogen chain-elongating enzyme glycogen synthase and inactivate the chain-shortening glycogen phosphorylase. Lafora disease is a fatal neurodegenerative epilepsy caused by aggregates of long-chained, and as a result insoluble, glycogen, termed Lafora bodies (LBs). We previously eliminated PPP1R3C from a Lafora disease mouse model and studied the effect on LB formation. In the present work, we eliminate and study the effect of absent PPP1R3D. In the interim, brain cell type levels of all PPP1R3 genes have been published, and brain cell type localization of LBs clarified. Integrating these data we find that PPP1R3C is the major isoform in most tissues including brain. In the brain, PPP1R3C is expressed at 15-fold higher levels than PPP1R3D in astrocytes, the cell type where most LBs form. PPP1R3C deficiency eliminates ~90% of brain LBs. PPP1R3D is quantitatively a minor isoform, but possesses unique MAPK, CaMK2 and 14-3-3 binding domains and appears to have an important functional niche in murine neurons and cardiomyocytes. In neurons, it is expressed equally to PPP1R3C, and its deficiency eliminates ~50% of neuronal LBs. In heart, it is expressed at 25% of PPP1R3C where its deficiency eliminates ~90% of LBs. This work studies the role of a second (PPP1R3D) of seven PP1 subunits that regulate the structure of glycogen, toward better understanding of brain glycogen metabolism generally, and in Lafora disease.
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Affiliation(s)
- Lori Israelian
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Silvia Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Peixiang Wang
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Jennifer P Y Lee
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Brandy Verhalen
- Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Felix Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Berge A Minassian
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Division of Neurology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
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5
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Sullivan MA, Nitschke S, Skwara EP, Wang P, Zhao X, Pan XS, Chown EE, Wang T, Perri AM, Lee JPY, Vilaplana F, Minassian BA, Nitschke F. Skeletal Muscle Glycogen Chain Length Correlates with Insolubility in Mouse Models of Polyglucosan-Associated Neurodegenerative Diseases. Cell Rep 2020; 27:1334-1344.e6. [PMID: 31042462 DOI: 10.1016/j.celrep.2019.04.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [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: 12/04/2018] [Revised: 01/29/2019] [Accepted: 04/02/2019] [Indexed: 01/31/2023] Open
Abstract
Lafora disease (LD) and adult polyglucosan body disease (APBD) are glycogen storage diseases characterized by a pathogenic buildup of insoluble glycogen. Mechanisms causing glycogen insolubility are poorly understood. Here, in two mouse models of LD (Epm2a-/- and Epm2b-/-) and one of APBD (Gbe1ys/ys), the separation of soluble and insoluble muscle glycogen is described, enabling separate analysis of each fraction. Total glycogen is increased in LD and APBD mice, which, together with abnormal chain length and molecule size distributions, is largely if not fully attributed to insoluble glycogen. Soluble glycogen consists of molecules with distinct chain length distributions and differential corresponding solubility, providing a mechanistic link between soluble and insoluble glycogen in vivo. Phosphorylation states differ across glycogen fractions and mouse models, demonstrating that hyperphosphorylation is not a basic feature of insoluble glycogen. Lastly, model-specific variances in protein and activity levels of key glycogen synthesis enzymes suggest uninvestigated regulatory mechanisms.
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Affiliation(s)
- Mitchell A Sullivan
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Glycation and Diabetes, Translational Research Institute, Mater Research Institute - University of Queensland, Brisbane, QLD 4102, Australia
| | - Silvia Nitschke
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Evan P Skwara
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Peixiang Wang
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Xiao S Pan
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Erin E Chown
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Travis Wang
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Jennifer P Y Lee
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Francisco Vilaplana
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm 10691, Sweden
| | - Berge A Minassian
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada; Division of Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Felix Nitschke
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada.
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6
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Nitschke F, Sullivan MA, Wang P, Zhao X, Chown EE, Perri AM, Israelian L, Juana-López L, Bovolenta P, Rodríguez de Córdoba S, Steup M, Minassian BA. Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease. EMBO Mol Med 2018; 9:906-917. [PMID: 28536304 PMCID: PMC5494504 DOI: 10.15252/emmm.201707608] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [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] [Indexed: 01/25/2023] Open
Abstract
Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss-of-function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase-inactive laforin rescues the laforin-deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin- or malin-deficient mouse lines expressing phosphatase-inactive laforin. We find that: (i) in laforin-deficient mice, phosphatase-inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin-deficient mice, phosphatase-inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD We conclude that laforin's principle function is to control glycogen chain lengths, in a malin-dependent fashion, and that loss of this control underlies LD.
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Affiliation(s)
- Felix Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Mitchell A Sullivan
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Glycation and Diabetes, Mater Research Institute, Translational Research Institute, The University of Queensland, Brisbane, Qld, Australia
| | - Peixiang Wang
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Erin E Chown
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Lori Israelian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Lucia Juana-López
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas and Ciber de Enfermedades Raras, Madrid, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM and Ciber de Enfermedades Raras, Universidad Autónoma de Madrid, Madrid, Spain
| | - Santiago Rodríguez de Córdoba
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas and Ciber de Enfermedades Raras, Madrid, Spain
| | - Martin Steup
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Berge A Minassian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada .,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, USA
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7
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Mucaki EJ, Caminsky NG, Perri AM, Lu R, Laederach A, Halvorsen M, Knoll JHM, Rogan PK. A unified analytic framework for prioritization of non-coding variants of uncertain significance in heritable breast and ovarian cancer. BMC Med Genomics 2016; 9:19. [PMID: 27067391 PMCID: PMC4828881 DOI: 10.1186/s12920-016-0178-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 03/15/2016] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Sequencing of both healthy and disease singletons yields many novel and low frequency variants of uncertain significance (VUS). Complete gene and genome sequencing by next generation sequencing (NGS) significantly increases the number of VUS detected. While prior studies have emphasized protein coding variants, non-coding sequence variants have also been proven to significantly contribute to high penetrance disorders, such as hereditary breast and ovarian cancer (HBOC). We present a strategy for analyzing different functional classes of non-coding variants based on information theory (IT) and prioritizing patients with large intragenic deletions. METHODS We captured and enriched for coding and non-coding variants in genes known to harbor mutations that increase HBOC risk. Custom oligonucleotide baits spanning the complete coding, non-coding, and intergenic regions 10 kb up- and downstream of ATM, BRCA1, BRCA2, CDH1, CHEK2, PALB2, and TP53 were synthesized for solution hybridization enrichment. Unique and divergent repetitive sequences were sequenced in 102 high-risk, anonymized patients without identified mutations in BRCA1/2. Aside from protein coding and copy number changes, IT-based sequence analysis was used to identify and prioritize pathogenic non-coding variants that occurred within sequence elements predicted to be recognized by proteins or protein complexes involved in mRNA splicing, transcription, and untranslated region (UTR) binding and structure. This approach was supplemented by in silico and laboratory analysis of UTR structure. RESULTS 15,311 unique variants were identified, of which 245 occurred in coding regions. With the unified IT-framework, 132 variants were identified and 87 functionally significant VUS were further prioritized. An intragenic 32.1 kb interval in BRCA2 that was likely hemizygous was detected in one patient. We also identified 4 stop-gain variants and 3 reading-frame altering exonic insertions/deletions (indels). CONCLUSIONS We have presented a strategy for complete gene sequence analysis followed by a unified framework for interpreting non-coding variants that may affect gene expression. This approach distills large numbers of variants detected by NGS to a limited set of variants prioritized as potential deleterious changes.
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Affiliation(s)
- Eliseos J Mucaki
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 2C1, Canada
| | - Natasha G Caminsky
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 2C1, Canada
| | - Ami M Perri
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 2C1, Canada
| | - Ruipeng Lu
- Department of Computer Science, Faculty of Science, Western University, London, N6A 2C1, Canada
| | - Alain Laederach
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3290, USA
| | - Matthew Halvorsen
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY, 10032, USA
| | - Joan H M Knoll
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, N6A 2C1, Canada
- Cytognomix Inc., London, Canada
| | - Peter K Rogan
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 2C1, Canada.
- Department of Computer Science, Faculty of Science, Western University, London, N6A 2C1, Canada.
- Cytognomix Inc., London, Canada.
- Department of Oncology, Schulich School of Medicine and Dentistry, Western University, London, N6A 2C1, Canada.
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8
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Caminsky NG, Mucaki EJ, Perri AM, Lu R, Knoll JHM, Rogan PK. Prioritizing Variants in Complete Hereditary Breast and Ovarian Cancer Genes in Patients Lacking Known BRCA Mutations. Hum Mutat 2016; 37:640-52. [PMID: 26898890 DOI: 10.1002/humu.22972] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [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: 09/08/2015] [Revised: 01/22/2016] [Accepted: 02/16/2016] [Indexed: 12/11/2022]
Abstract
BRCA1 and BRCA2 testing for hereditary breast and ovarian cancer (HBOC) does not identify all pathogenic variants. Sequencing of 20 complete genes in HBOC patients with uninformative test results (N = 287), including noncoding and flanking sequences of ATM, BARD1, BRCA1, BRCA2, CDH1, CHEK2, EPCAM, MLH1, MRE11A, MSH2, MSH6, MUTYH, NBN, PALB2, PMS2, PTEN, RAD51B, STK11, TP53, and XRCC2, identified 38,372 unique variants. We apply information theory (IT) to predict and prioritize noncoding variants of uncertain significance in regulatory, coding, and intronic regions based on changes in binding sites in these genes. Besides mRNA splicing, IT provides a common framework to evaluate potential affinity changes in transcription factor (TFBSs), splicing regulatory (SRBSs), and RNA-binding protein (RBBSs) binding sites following mutation. We prioritized variants affecting the strengths of 10 splice sites (four natural, six cryptic), 148 SRBS, 36 TFBS, and 31 RBBS. Three variants were also prioritized based on their predicted effects on mRNA secondary (2°) structure and 17 for pseudoexon activation. Additionally, four frameshift, two in-frame deletions, and five stop-gain mutations were identified. When combined with pedigree information, complete gene sequence analysis can focus attention on a limited set of variants in a wide spectrum of functional mutation types for downstream functional and co-segregation analysis.
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Affiliation(s)
- Natasha G Caminsky
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Eliseos J Mucaki
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Ami M Perri
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Ruipeng Lu
- Department of Computer Science, Faculty of Science, Western University, London, Ontario, Canada
| | - Joan H M Knoll
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Cytognomix Inc, London, Ontario, Canada
| | - Peter K Rogan
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Computer Science, Faculty of Science, Western University, London, Ontario, Canada.,Cytognomix Inc, London, Ontario, Canada.,Department of Oncology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
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9
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Nesset KA, Perri AM, Mueller CR. Frequent promoter hypermethylation and expression reduction of the glucocorticoid receptor gene in breast tumors. Epigenetics 2014; 9:851-9. [PMID: 24622770 DOI: 10.4161/epi.28484] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Previous studies have found that expression of the Glucocorticoid Receptor (GR) is altered or reduced in various cancers, while the GR promoter has been shown to be methylated in gastric, lung, and colorectal cancers. Examining a small cohort of matched normal and breast cancer samples we found that GR levels were dramatically reduced in almost all tumors in relation to their normal tissue. The methylation status of the GR promoter was assessed to determine if this observed decrease of expression in breast tumors could be due to epigenetic regulation. While it was not methylated in normal tissue, the GR proximal promoter was methylated in 15% of tumor samples, particularly, but not exclusively, in Estrogen Receptor positive tumors. GR expression in these tumors was particularly low and loss of GR expression was specifically correlated with methylation of the proximal promoter GR B region. Overall, these results show that hypermethylation of the promoter in tumors is a frequent event and suggests that GR may act as a tumor suppressor in breast tissue.
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Affiliation(s)
- Kirsten A Nesset
- Department of Biomedical and Molecular Sciences; Department of Pathology and Molecular Medicine; Queen's Cancer Research Institute; Queen's University; Kingston, ON Canada
| | - Ami M Perri
- Department of Biomedical and Molecular Sciences; Department of Pathology and Molecular Medicine; Queen's Cancer Research Institute; Queen's University; Kingston, ON Canada
| | - Christopher R Mueller
- Department of Biomedical and Molecular Sciences; Department of Pathology and Molecular Medicine; Queen's Cancer Research Institute; Queen's University; Kingston, ON Canada
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Lachance MA, Perri AM, Farahbakhsh AS, Starmer WT. Genetic structure ofKurtzmaniella cleridarum, a cactus flower beetle yeast of the Sonoran and Mojave Deserts: speciation by distance? FEMS Yeast Res 2013; 13:674-81. [DOI: 10.1111/1567-1364.12066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/09/2013] [Accepted: 07/09/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
| | - Ami M. Perri
- Department of Biology; University of Western Ontario; London; ON; Canada
| | - Amy S. Farahbakhsh
- Department of Biology; University of Western Ontario; London; ON; Canada
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