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Cataldi MP, Vannoy CH, Blaeser A, Tucker JD, Leroy V, Rawls R, Killilee J, Holbrook MC, Lu QL. Improved efficacy of FKRP AAV gene therapy by combination with ribitol treatment for LGMD2I. Mol Ther 2023; 31:3478-3489. [PMID: 37919902 PMCID: PMC10727973 DOI: 10.1016/j.ymthe.2023.10.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/05/2023] [Accepted: 10/31/2023] [Indexed: 11/04/2023] Open
Abstract
Mutations in the fukutin-related protein (FKRP) gene cause dystroglycanopathy, with disease severity ranging from mild LGMD2I to severe congenital muscular dystrophy. Recently, considerable progress has been made in developing experimental therapies, with adeno-associated virus (AAV) gene therapy and ribitol treatment demonstrating significant therapeutic effect. However, each treatment has its strengths and weaknesses. AAV gene therapy can achieve normal levels of transgene expression, but it requires high doses, with toxicity concerns and variable distribution. Ribitol relies on residual FKRP function and restores limited levels of matriglycan. We hypothesized that these two treatments can work synergistically to offer an optimized therapy with efficacy and safety unmatched by each treatment alone. The most effective treatment is the combination of high-dose (5e-13 vg/kg) AAV-FKRP with ribitol, whereas low dose (1e-13 vg/kg) AAV-FKRP combined with ribitol showed a 22.6% increase in positive matriglycan fibers and the greater improvement in pathology when compared to low-dose AAV-FKRP alone. Together, our results support the potential benefits of combining ribitol with AAV gene therapy for treating FKRP-related muscular dystrophy. The fact that ribitol is a metabolite in nature and has already been tested in animal models and clinical trials in humans without severe side effects provides a safety profile for it to be trialed in combination with AAV gene therapy.
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Affiliation(s)
- Marcela P Cataldi
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA.
| | - Charles H Vannoy
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Anthony Blaeser
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Jason D Tucker
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Victoria Leroy
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Raegan Rawls
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Jessalyn Killilee
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Molly C Holbrook
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Qi Long Lu
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA.
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Kuwabara N, Imae R, Manya H, Tanaka T, Mizuno M, Tsumoto H, Kanagawa M, Kobayashi K, Toda T, Senda T, Endo T, Kato R. Crystal structures of fukutin-related protein (FKRP), a ribitol-phosphate transferase related to muscular dystrophy. Nat Commun 2020; 11:303. [PMID: 31949166 PMCID: PMC6965139 DOI: 10.1038/s41467-019-14220-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 12/10/2019] [Indexed: 12/16/2022] Open
Abstract
α-Dystroglycan (α-DG) is a highly-glycosylated surface membrane protein. Defects in the O-mannosyl glycan of α-DG cause dystroglycanopathy, a group of congenital muscular dystrophies. The core M3 O-mannosyl glycan contains tandem ribitol-phosphate (RboP), a characteristic feature first found in mammals. Fukutin and fukutin-related protein (FKRP), whose mutated genes underlie dystroglycanopathy, sequentially transfer RboP from cytidine diphosphate-ribitol (CDP-Rbo) to form a tandem RboP unit in the core M3 glycan. Here, we report a series of crystal structures of FKRP with and without donor (CDP-Rbo) and/or acceptor [RboP-(phospho-)core M3 peptide] substrates. FKRP has N-terminal stem and C-terminal catalytic domains, and forms a tetramer both in crystal and in solution. In the acceptor complex, the phosphate group of RboP is recognized by the catalytic domain of one subunit, and a phosphate group on O-mannose is recognized by the stem domain of another subunit. Structure-based functional studies confirmed that the dimeric structure is essential for FKRP enzymatic activity. Fukutin-related protein (FKRP) catalyses the addition of ribitol-phosphate (RboP) to the O-mannosyl glycan of α-dystroglycan and mutations in FKRP cause dystroglycanopathy. Here the authors provide insights into its oligomerization and recognition of the substrates, CDP-Rbo and the RboP-(phospho-)core M3 glycan, by determining the crystal structures of human FKRP.
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Affiliation(s)
- Naoyuki Kuwabara
- Structural Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Rieko Imae
- Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Hiroshi Manya
- Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Tomohiro Tanaka
- Laboratory of Glyco-organic Chemistry, The Noguchi Institute, Itabashi-ku, Tokyo, 173-0003, Japan
| | - Mamoru Mizuno
- Laboratory of Glyco-organic Chemistry, The Noguchi Institute, Itabashi-ku, Tokyo, 173-0003, Japan
| | - Hiroki Tsumoto
- Proteome Research, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Motoi Kanagawa
- Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Hyogo, 650-0017, Japan
| | - Kazuhiro Kobayashi
- Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Hyogo, 650-0017, Japan
| | - Tatsushi Toda
- Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Hyogo, 650-0017, Japan.,Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Toshiya Senda
- Structural Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan.,School of High Energy Accelerator Science, SOKENDAI, Tsukuba, Ibaraki, 305-0801, Japan
| | - Tamao Endo
- Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi-ku, Tokyo, 173-0015, Japan.
| | - Ryuichi Kato
- Structural Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan. .,School of High Energy Accelerator Science, SOKENDAI, Tsukuba, Ibaraki, 305-0801, Japan.
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3
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Vannoy CH, Leroy V, Lu QL. Dose-Dependent Effects of FKRP Gene-Replacement Therapy on Functional Rescue and Longevity in Dystrophic Mice. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2018; 11:106-120. [PMID: 30417025 PMCID: PMC6222079 DOI: 10.1016/j.omtm.2018.10.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/08/2018] [Indexed: 12/31/2022]
Abstract
Muscular dystrophy-dystroglycanopathies (MDDGs) resulting from fukutin-related protein (FKRP) gene mutations are rare disorders that result in a wide spectrum of clinical severity based on the age of onset, the degree of myogenic atrophy, and/or neurologic involvement. There is no cure for any of the FKRP-related disorders, and few options are available for symptom management. Herein, we examine the longitudinal effects of a dose-escalation study to evaluate the safety and therapeutic potential of FKRP gene-replacement therapy in a p.P448L (FKRPP448L) mouse model of MDDG. A recombinant adeno-associated virus (AAV) serotype 9 vector expressing human FKRP (AAV9-FKRP) was systemically administered to FKRPP448L mice at 5 weeks of age, when early onset of the disease is evidenced. A comprehensive analysis of protein and gene expression, histopathology, skeletal muscle function, and cardiorespiratory function was performed over short (9-week) and/or long-term (52-week) study periods. Additional studies assessed the impact of FKRP gene-replacement therapy on lifespan at an advanced stage of disease progression. Results indicate that treatment intervention can restore the biochemical defects in a dose-dependent manner, with potential for improvement in the trajectory of disease progression and extension of the expected lifespan. This study supports the initiation of early-stage clinical trials for FKRP-related disorders.
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Affiliation(s)
- Charles Harvey Vannoy
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
- Corresponding author: Charles Harvey Vannoy, McColl-Lockwood Laboratory for Muscular Dystrophy Research, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA.
| | - Victoria Leroy
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
| | - Qi Long Lu
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA
- Corresponding author: Qi Long Lu, McColl-Lockwood Laboratory for Muscular Dystrophy Research, Carolinas Medical Center, Atrium Health, Charlotte, NC 28203, USA.
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4
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Cho EB, Yoo W, Yoon SK, Yoon JB. β-dystroglycan is regulated by a balance between WWP1-mediated degradation and protection from WWP1 by dystrophin and utrophin. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2199-2213. [PMID: 29635000 DOI: 10.1016/j.bbadis.2018.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/20/2018] [Accepted: 04/03/2018] [Indexed: 01/07/2023]
Abstract
Dystroglycan is a ubiquitous membrane protein that functions as a mechanical connection between the extracellular matrix and cytoskeleton. In skeletal muscle, dystroglycan plays an indispensable role in regulating muscle regeneration; a malfunction in dystroglycan is associated with muscular dystrophy. The regulation of dystroglycan stability is poorly understood. Here, we report that WWP1, a member of NEDD4 E3 ubiquitin ligase family, promotes ubiquitination and subsequent degradation of β-dystroglycan. Our results indicate that dystrophin and utrophin protect β-dystroglycan from WWP1-mediated degradation by competing with WWP1 for the shared binding site at the cytosolic tail of β-dystroglycan. In addition, we show that a missense mutation (arginine 440 to glutamine) in WWP1-which is known to cause muscular dystrophy in chickens-increases the ubiquitin ligase-mediated ubiquitination of both β-dystroglycan and WWP1. The R440Q missense mutation in WWP1 decreases HECT domain-mediated intramolecular interactions to relieve autoinhibition of the enzyme. Our results provide new insight into the regulation of β-dystroglycan degradation by WWP1 and other Nedd4 family members and improves our understanding of dystroglycan-related disorders.
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Affiliation(s)
- Eun-Bee Cho
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Wonjin Yoo
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Sungjoo Kim Yoon
- Department of Medical Lifesciences, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Jong-Bok Yoon
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
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5
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Frattini P, Villa C, De Santis F, Meregalli M, Belicchi M, Erratico S, Bella P, Raimondi MT, Lu Q, Torrente Y. Autologous intramuscular transplantation of engineered satellite cells induces exosome-mediated systemic expression of Fukutin-related protein and rescues disease phenotype in a murine model of limb-girdle muscular dystrophy type 2I. Hum Mol Genet 2018; 26:3682-3698. [PMID: 28666318 PMCID: PMC5886111 DOI: 10.1093/hmg/ddx252] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 06/28/2017] [Indexed: 12/20/2022] Open
Abstract
α-Dystroglycanopathies are a group of muscular dystrophies characterized by α-DG hypoglycosylation and reduced extracellular ligand-binding affinity. Among other genes involved in the α-DG glycosylation process, fukutin related protein (FKRP) gene mutations generate a wide range of pathologies from mild limb girdle muscular dystrophy 2I (LGMD2I), severe congenital muscular dystrophy 1C (MDC1C), to Walker-Warburg Syndrome and Muscle-Eye-Brain disease. FKRP gene encodes for a glycosyltransferase that in vivo transfers a ribitol phosphate group from a CDP –ribitol present in muscles to α-DG, while in vitro it can be secreted as monomer of 60kDa. Consistently, new evidences reported glycosyltransferases in the blood, freely circulating or wrapped within vesicles. Although the physiological function of blood stream glycosyltransferases remains unclear, they are likely released from blood borne or distant cells. Thus, we hypothesized that freely or wrapped FKRP might circulate as an extracellular glycosyltransferase, able to exert a “glycan remodelling” process, even at distal compartments. Interestingly, we firstly demonstrated a successful transduction of MDC1C blood-derived CD133+ cells and FKRP L276IKI mouse derived satellite cells by a lentiviral vector expressing the wild-type of human FKRP gene. Moreover, we showed that LV-FKRP cells were driven to release exosomes carrying FKRP. Similarly, we observed the presence of FKRP positive exosomes in the plasma of FKRP L276IKI mice intramuscularly injected with engineered satellite cells. The distribution of FKRP protein boosted by exosomes determined its restoration within muscle tissues, an overall recovery of α-DG glycosylation and improved muscle strength, suggesting a systemic supply of FKRP protein acting as glycosyltransferase.
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Affiliation(s)
- Paola Frattini
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy
| | - Chiara Villa
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy
| | - Francesca De Santis
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy
| | - Mirella Meregalli
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy.,Novystem S.r.l., Milan, Italy
| | - Marzia Belicchi
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy.,Novystem S.r.l., Milan, Italy
| | | | - Pamela Bella
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy
| | - Manuela Teresa Raimondi
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Qilong Lu
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Neuromuscular/ALS Center, Department of Neurology, Carolinas Medical Center, Charlotte, North Carolina, NC, USA
| | - Yvan Torrente
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Unit of Neurology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Centro Dino Ferrari, Milan, Italy.,Novystem S.r.l., Milan, Italy.,Ystem S.r.l., Milan, Italy
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6
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Glucocorticoid Steroid and Alendronate Treatment Alleviates Dystrophic Phenotype with Enhanced Functional Glycosylation of α-Dystroglycan in Mouse Model of Limb-Girdle Muscular Dystrophy with FKRPP448L Mutation. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:1635-48. [DOI: 10.1016/j.ajpath.2016.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 02/02/2016] [Accepted: 02/19/2016] [Indexed: 12/13/2022]
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7
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Abdelmagid SM, Belcher JY, Moussa FM, Lababidi SL, Sondag GR, Novak KM, Sanyurah AS, Frara NA, Razmpour R, Del Carpio-Cano FE, Safadi FF. Mutation in osteoactivin decreases bone formation in vivo and osteoblast differentiation in vitro. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:697-713. [PMID: 24462663 DOI: 10.1016/j.ajpath.2013.11.031] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/19/2013] [Accepted: 11/26/2013] [Indexed: 11/25/2022]
Abstract
We have previously identified osteoactivin (OA), encoded by Gpnmb, as an osteogenic factor that stimulates osteoblast differentiation in vitro. To elucidate the importance of OA in osteogenesis, we characterized the skeletal phenotype of a mouse model, DBA/2J (D2J) with a loss-of-function mutation in Gpnmb. Microtomography of D2J mice showed decreased trabecular mass, compared to that in wild-type mice [DBA/2J-Gpnmb(+)/SjJ (D2J/Gpnmb(+))]. Serum analysis showed decreases in OA and the bone-formation markers alkaline phosphatase and osteocalcin in D2J mice. Although D2J mice showed decreased osteoid and mineralization surfaces, their osteoblasts were increased in number, compared to D2J/Gpnmb(+) mice. We then examined the ability of D2J osteoblasts to differentiate in culture, where their differentiation and function were decreased, as evidenced by low alkaline phosphatase activity and matrix mineralization. Quantitative RT-PCR analyses confirmed the decreased expression of differentiation markers in D2J osteoblasts. In vitro, D2J osteoblasts proliferated and survived significantly less, compared to D2J/Gpnmb(+) osteoblasts. Next, we investigated whether mutant OA protein induces endoplasmic reticulum stress in D2J osteoblasts. Neither endoplasmic reticulum stress markers nor endoplasmic reticulum ultrastructure were altered in D2J osteoblasts. Finally, we assessed underlying mechanisms that might alter proliferation of D2J osteoblasts. Interestingly, TGF-β receptors and Smad-2/3 phosphorylation were up-regulated in D2J osteoblasts, suggesting that OA contributes to TGF-β signaling. These data confirm the anabolic role of OA in postnatal bone formation.
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Affiliation(s)
- Samir M Abdelmagid
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio
| | - Joyce Y Belcher
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio
| | - Fouad M Moussa
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio; School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Suzanne L Lababidi
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio
| | - Gregory R Sondag
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio; School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Kimberly M Novak
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio
| | - Afif S Sanyurah
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio; School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Nagat A Frara
- Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Roshanak Razmpour
- Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Fabiola E Del Carpio-Cano
- Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Fayez F Safadi
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio; School of Biomedical Sciences, Kent State University, Kent, Ohio.
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8
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Alhamidi M, Kjeldsen Buvang E, Fagerheim T, Brox V, Lindal S, Van Ghelue M, Nilssen Ø. Fukutin-related protein resides in the Golgi cisternae of skeletal muscle fibres and forms disulfide-linked homodimers via an N-terminal interaction. PLoS One 2011; 6:e22968. [PMID: 21886772 PMCID: PMC3160285 DOI: 10.1371/journal.pone.0022968] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 07/04/2011] [Indexed: 12/01/2022] Open
Abstract
Limb-Girdle Muscular Dystrophy type 2I (LGMD2I) is an inheritable autosomal, recessive disorder caused by mutations in the FuKutin-Related Protein (FKRP) gene (FKRP) located on chromosome 19 (19q13.3). Mutations in FKRP are also associated with Congenital Muscular Dystrophy (MDC1C), Walker-Warburg Syndrome (WWS) and Muscle Eye Brain disease (MEB). These four disorders share in common an incomplete/aberrant O-glycosylation of the membrane/extracellular matrix (ECM) protein α-dystroglycan. However, further knowledge on the FKRP structure and biological function is lacking, and its intracellular location is controversial. Based on immunogold electron microscopy of human skeletal muscle sections we demonstrate that FKRP co-localises with the middle-to-trans-Golgi marker MG160, between the myofibrils in human rectus femoris muscle fibres. Chemical cross-linking experiments followed by pairwise yeast 2-hybrid experiments, and co-immune precipitation, demonstrate that FKRP can exist as homodimers as well as in large multimeric protein complexes when expressed in cell culture. The FKRP homodimer is kept together by a disulfide bridge provided by the most N-terminal cysteine, Cys6. FKRP contains N-glycan of high mannose and/or hybrid type; however, FKRP N-glycosylation is not required for FKRP homodimer or multimer formation. We propose a model for FKRP which is consistent with that of a Golgi resident type II transmembrane protein.
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Affiliation(s)
- Maisoon Alhamidi
- Division of Child and Adolescent Health, Department of Medical Genetics, University Hospital of North-Norway, Tromsø, Norway
- Department of Clinical Medicine – Medical Genetics, University of Tromsø, Tromsø, Norway
| | | | - Toril Fagerheim
- Division of Child and Adolescent Health, Department of Medical Genetics, University Hospital of North-Norway, Tromsø, Norway
| | - Vigdis Brox
- Division of Child and Adolescent Health, Department of Medical Genetics, University Hospital of North-Norway, Tromsø, Norway
| | - Sigurd Lindal
- Department of Pathology, University Hospital of North-Norway, Tromsø, Norway
- Institute of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Marijke Van Ghelue
- Division of Child and Adolescent Health, Department of Medical Genetics, University Hospital of North-Norway, Tromsø, Norway
- Department of Clinical Medicine – Medical Genetics, University of Tromsø, Tromsø, Norway
| | - Øivind Nilssen
- Division of Child and Adolescent Health, Department of Medical Genetics, University Hospital of North-Norway, Tromsø, Norway
- Department of Clinical Medicine – Medical Genetics, University of Tromsø, Tromsø, Norway
- * E-mail:
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Hong D, Zhang W, Wang W, Wang Z, Yuan Y. Asian patients with limb girdle muscular dystrophy 2I (LGMD2I). J Clin Neurosci 2011; 18:494-9. [PMID: 21296577 DOI: 10.1016/j.jocn.2010.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 05/20/2010] [Accepted: 08/02/2010] [Indexed: 11/25/2022]
Abstract
Limb girdle muscular dystrophy type 2I (LGMD2I) is caused by defects in the fukutin-related protein (FKRP) gene. In most Caucasian patients with LGMD2I, the condition is associated with a missense mutation - c.826C>A (p.Leu276Ile). We describe two Chinese brothers with progressive shoulder and pelvic muscle weakness. They had muscle stiffness and myalgia after exercise, but lacked obvious hypertrophy of the calves. Muscle biopsy showed dystrophic features with many rimmed vacuoles in the fibers. Immunohistochemistry and immunoblot analyses revealed reductions of alpha-(α)-dystroglycan (VIA4-1) and laminin-α2 (80-kDa C-terminal and 300-kDaN-terminal). Two novel heterozygous mutations (c.208T>A and c.1030G>T) in the FKRP gene were identified in these patients. In addition, we summarise the clinical features of patients with LGMD2I in the Asian region. Our findings might indicate that the pathogenic FKRP mutations in Asian patients with LGMD2I are sporadic compound heterozygous mutations rather than the hot-spot c.826C>A mutation seen in Caucasian populations.
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Affiliation(s)
- Daojun Hong
- Department of Neurology, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing 100034, China
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10
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Post-Natal knockdown of fukutin-related protein expression in muscle by long-termRNA interference induces dystrophic pathology [corrected]. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 178:261-72. [PMID: 21224063 DOI: 10.1016/j.ajpath.2010.11.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 08/08/2010] [Accepted: 09/08/2010] [Indexed: 01/15/2023]
Abstract
Limb-girdle muscular dystrophy 2I (LGMD2I) is caused by mutations in the fukutin-related protein (FKRP) gene. Unlike its severe allelic forms, LGMD2I usually involves slower onset and milder course without defects in the central nervous system. The lack of viable animal models that closely recapitulate LGMD2I clinical phenotypes led us to use RNA interference technology to knock down FKRP expression via postnatal gene delivery so as to circumvent embryonic lethality. Specifically, an adeno-associated viral vector was used to deliver short hairpin (shRNA) genes to healthy ICR mice. Adeno-associated viral vectors expressing a single shRNA or two different shRNAs were injected one time into the hind limb muscles. We showed that FKRP expression at 10 months postinjection was reduced by about 50% with a single shRNA and by 75% with the dual shRNA cassette. Dual-cassette injection also reduced a-dystroglycan glycosylation and its affinity to laminin by up to 70% and induced α-dystrophic pathology, including fibrosis and central nucleation, in more than 50% of the myofibers at 10 months after injection. These results suggest that the reduction of approximately or more than 75% of the normal level of FKRP expression induces chronic dystrophic phenotypes in skeletal muscles. Furthermore, the restoration of about 25% of the normal FKRP level could be sufficient for LGMD2I therapy to correct the genetic deficiency effectively and prevent dystrophic pathology.
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Chan YM, Keramaris-Vrantsis E, Lidov HG, Norton JH, Zinchenko N, Gruber HE, Thresher R, Blake DJ, Ashar J, Rosenfeld J, Lu QL. Fukutin-related protein is essential for mouse muscle, brain and eye development and mutation recapitulates the wide clinical spectrums of dystroglycanopathies. Hum Mol Genet 2010; 19:3995-4006. [PMID: 20675713 DOI: 10.1093/hmg/ddq314] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in fukutin-related protein (FKRP) cause a common subset of muscular dystrophies characterized by aberrant glycosylation of alpha-dystroglycan (α-DG), collectively known as dystroglycanopathies. The clinical variations associated with FKRP mutations range from mild limb-girdle muscular dystrophy type 2I with predominantly muscle phenotypes to severe Walker-Warburg syndrome and muscle-eye-brain disease with striking structural brain and eye defects. In the present study, we have generated animal models and demonstrated that ablation of FKRP functions is embryonic lethal and that the homozygous-null embryos die before reaching E12.5. The homozygous knock-in mouse carrying the missense P448L mutation almost completely lacks functional glycosylation of α-DG in muscles and brain, validating the essential role of FKRP in the functional glycosylation of α-DG. However, the knock-in mouse survives and develops a wide range of structural abnormalities in the central nervous system, characteristics of neuronal migration defects. The brain and eye defects are highly reminiscent of the phenotypes seen in severe dystroglycanopathy patients. In addition, skeletal muscles develop progressive muscular dystrophy. Our results confirm that post-translational modifications of α-DG are essential for normal development of the brain and eyes. In addition, both the mutation itself and the levels of FKRP expression are equally critical for the survival of the animals. The exceptionally wide clinical spectrums recapitulated in the P448L mice also suggest the involvement of other factors in the disease progression. The mutant mouse represents a valuable model to further elucidate the functions of FKRP and develop therapies for FKRP-related muscular dystrophies.
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Affiliation(s)
- Yiumo Michael Chan
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Neuromuscular/ALS Center, Carolinas Medical Center, Charlotte, NC 28231, USA
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