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Wheeler JR, Whitney ON, Vogler TO, Nguyen ED, Pawlikowski B, Lester E, Cutler A, Elston T, Dalla Betta N, Parker KR, Yost KE, Vogel H, Rando TA, Chang HY, Johnson AM, Parker R, Olwin BB. RNA-binding proteins direct myogenic cell fate decisions. eLife 2022; 11:e75844. [PMID: 35695839 PMCID: PMC9191894 DOI: 10.7554/elife.75844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
RNA-binding proteins (RBPs), essential for skeletal muscle regeneration, cause muscle degeneration and neuromuscular disease when mutated. Why mutations in these ubiquitously expressed RBPs orchestrate complex tissue regeneration and direct cell fate decisions in skeletal muscle remains poorly understood. Single-cell RNA-sequencing of regenerating Mus musculus skeletal muscle reveals that RBP expression, including the expression of many neuromuscular disease-associated RBPs, is temporally regulated in skeletal muscle stem cells and correlates with specific stages of myogenic differentiation. By combining machine learning with RBP engagement scoring, we discovered that the neuromuscular disease-associated RBP Hnrnpa2b1 is a differentiation-specifying regulator of myogenesis that controls myogenic cell fate transitions during terminal differentiation in mice. The timing of RBP expression specifies cell fate transitions by providing post-transcriptional regulation of messenger RNAs that coordinate stem cell fate decisions during tissue regeneration.
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Affiliation(s)
- Joshua R Wheeler
- Department of Biochemistry, University of ColoradoBoulderUnited States
- Medical Scientist Training Program, University of Colorado Anschutz Medical CampusAuroraUnited States
- Howard Hughes Medical Institute, University of ColoradoBoulderUnited States
- Department of Pathology, Stanford UniversityStanfordUnited States
- Department of Neuropathology, Stanford UniversityStanfordUnited States
| | - Oscar N Whitney
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Thomas O Vogler
- Medical Scientist Training Program, University of Colorado Anschutz Medical CampusAuroraUnited States
- Department of Molecular, Cellular and Developmental Biology, University of ColoradoBoulderUnited States
- Department of Surgery, University of ColoradoAuroraUnited States
| | - Eric D Nguyen
- Medical Scientist Training Program, University of Colorado Anschutz Medical CampusAuroraUnited States
- Molecular Biology Program and Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Bradley Pawlikowski
- Department of Molecular, Cellular and Developmental Biology, University of ColoradoBoulderUnited States
| | - Evan Lester
- Department of Biochemistry, University of ColoradoBoulderUnited States
- Medical Scientist Training Program, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Alicia Cutler
- Department of Molecular, Cellular and Developmental Biology, University of ColoradoBoulderUnited States
| | - Tiffany Elston
- Department of Molecular, Cellular and Developmental Biology, University of ColoradoBoulderUnited States
| | - Nicole Dalla Betta
- Department of Molecular, Cellular and Developmental Biology, University of ColoradoBoulderUnited States
| | - Kevin R Parker
- Center for Personal and Dynamic Regulomes, Stanford UniversityPalo AltoUnited States
| | - Kathryn E Yost
- Center for Personal and Dynamic Regulomes, Stanford UniversityPalo AltoUnited States
| | - Hannes Vogel
- Department of Pathology, Stanford UniversityStanfordUnited States
| | - Thomas A Rando
- Department of Neurology and Neurological Sciences, Stanford University School of MedicineStanfordUnited States
- Paul F. Glenn Center for the Biology of Aging, Stanford University School of MedicineStanfordUnited States
- Center for Tissue Regeneration, Repair, and Restoration, Veterans Affairs Palo Alto Health Care SystemPalo AltoUnited States
| | - Howard Y Chang
- Center for Personal and Dynamic Regulomes, Stanford UniversityPalo AltoUnited States
- Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
| | - Aaron M Johnson
- Molecular Biology Program and Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical CampusAuroraUnited States
- University of Colorado School of Medicine, RNA Bioscience Initiative, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Roy Parker
- Howard Hughes Medical Institute, University of ColoradoBoulderUnited States
| | - Bradley B Olwin
- Department of Molecular, Cellular and Developmental Biology, University of ColoradoBoulderUnited States
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Sun J, Yang H, Yang X, Chen X, Xu H, Shen Y, Ding F, Gu X, Zhu J, Sun H. Global alternative splicing landscape of skeletal muscle atrophy induced by hindlimb unloading. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:643. [PMID: 33987341 PMCID: PMC8106077 DOI: 10.21037/atm-20-5388] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Background Long-term exposure to microgravity will cause skeletal muscle atrophy, which can cause serious harm to astronauts in space travel. Therefore, it is important to explore skeletal muscle atrophy’s molecular mechanism for its prevention and treatment. However, as an important regulatory approach of skeletal muscle physiology, the role of alternative splicing in skeletal muscle atrophy, especially skeletal muscle atrophy caused by disuse, is unclear. Methods We established a rat hindlimb unloading model and performed RNA sequencing on soleus muscle, which was seriously atrophied during unloading. Several bioinformatics methods were used to identify alternative splicing events and determine their gene functions. Results Many alternative splicing events were found to occur at different time points (12 h, 24 h, 36 h, 3 days, and 7 days) after hindlimb unloading. These differential alternative splicing events mainly occurred in the gene's coding domain sequence region, and 59% of the alternative splicing events caused open reading frameshift. Bioinformatics analysis results showed that genes with different alternative splicing events were enriched in multiple pathways related to muscle atrophy, including the insulin signaling pathway, endocytosis, mitophagy, and ubiquitin-proteasome pathway. Moreover, alternative splicing of several deubiquitinase genes persisted during skeletal muscle atrophy induced by unloading. Additionally, we identified 10 differentially expressed RNA binding proteins during skeletal muscle atrophy induced by unloading, mainly containing Xpo4, Eif4e2, P4ha1, Lrrfip1, Zc3h14, Emg1, Hnrnp h1, Mbnl2, RBfox1, and Mbnl1. Hnrnp h1 and Mbnl2 were significantly downregulated, and RBfox1 and Mbnl1 were significantly upregulated during skeletal muscle atrophy caused by unloading. Conclusions To the best of our knowledge, the present study is the first to propose alternative splicing alterations related to disuse-induced muscle atrophy, emphasizing that alternative splicing is a new focus of attention in the occurrence of muscle atrophy.
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Affiliation(s)
- Junjie Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Hua Yang
- Department of Neurosurgery, People's Hospital of Binhai County, Yancheng, China
| | - Xiaoming Yang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Xin Chen
- Department of Neurology, Department of Orthopedics, Affiliated Hospital of Nantong University, Nantong, China
| | - Hua Xu
- Department of Neurology, Department of Orthopedics, Affiliated Hospital of Nantong University, Nantong, China
| | - Yuntian Shen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Fei Ding
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Xiaosong Gu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Jianwei Zhu
- Department of Neurology, Department of Orthopedics, Affiliated Hospital of Nantong University, Nantong, China
| | - Hualin Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
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3
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Maimaiti R, Zhu C, Zhang Y, Ding Q, Guo W. RBM20-Mediated Pre-mRNA Splicing Has Muscle-Specificity and Differential Hormonal Responses between Muscles and in Muscle Cell Cultures. Int J Mol Sci 2021; 22:2928. [PMID: 33805770 PMCID: PMC7999644 DOI: 10.3390/ijms22062928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 11/16/2022] Open
Abstract
Pre-mRNA splicing plays an important role in muscle function and diseases. The RNA binding motif 20 (RBM20) is a splicing factor that is predominantly expressed in muscle tissues and primarily regulates pre-mRNA splicing of Ttn, encoding a giant muscle protein titin that is responsible for muscle function and diseases. RBM20-mediated Ttn splicing has been mostly studied in heart muscle, but not in skeletal muscle. In this study, we investigated splicing specificity in different muscle types in Rbm20 knockout rats and hormonal effects on RBM20-mediated splicing both in cellulo and in vivo studies. The results revealed that RBM20 is differentially expressed across muscles and RBM20-mediated splicing is muscle-type specific. In the presence of RBM20, Ttn splicing responds to hormones in a muscle-type dependent manner, while in the absence of RBM20, Ttn splicing is not affected by hormones. In differentiated and undifferentiated C2C12 cells, RBM20-mediated splicing in response to hormonal effects is mainly through genomic signaling pathway. The knowledge gained from this study may help further understand muscle-specific gene splicing in response to hormone stimuli in different muscle types.
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Affiliation(s)
- Rexiati Maimaiti
- Animal Science Department, University of Wyoming, Laramie, WY 82071, USA; (R.M.); (C.Z.)
| | - Chaoqun Zhu
- Animal Science Department, University of Wyoming, Laramie, WY 82071, USA; (R.M.); (C.Z.)
| | - Yanghai Zhang
- Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (Y.Z.); (Q.D.)
| | - Qiyue Ding
- Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (Y.Z.); (Q.D.)
| | - Wei Guo
- Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (Y.Z.); (Q.D.)
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Cicardi ME, Cristofani R, Crippa V, Ferrari V, Tedesco B, Casarotto E, Chierichetti M, Galbiati M, Piccolella M, Messi E, Carra S, Pennuto M, Rusmini P, Poletti A. Autophagic and Proteasomal Mediated Removal of Mutant Androgen Receptor in Muscle Models of Spinal and Bulbar Muscular Atrophy. Front Endocrinol (Lausanne) 2019; 10:569. [PMID: 31481932 PMCID: PMC6710630 DOI: 10.3389/fendo.2019.00569] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 08/05/2019] [Indexed: 12/25/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an X-linked motoneuron disease (MND) caused by a mutant androgen receptor (AR) containing an elongated polyglutamine (polyQ) tract. ARpolyQ toxicity is triggered by androgenic AR ligands, which induce aberrant conformations (misfolding) of the ARpolyQ protein that aggregates. Misfolded proteins perturb the protein quality control (PQC) system leading to cell dysfunction and death. Spinal cord motoneurons, dorsal root ganglia neurons and skeletal muscle cells are affected by ARpolyQ toxicity. Here, we found that, in stabilized skeletal myoblasts (s-myoblasts), ARpolyQ formed testosterone-inducible aggregates resistant to NP-40 solubilization; these aggregates did not affect s-myoblasts survival or viability. Both wild type AR and ARpolyQ were processed via proteasome, but ARpolyQ triggered (and it was also cleared via) autophagy. ARpolyQ reduced two pro-autophagic proteins expression (BAG3 and VCP), leading to decreased autophagic response in ARpolyQ s-myoblasts. Overexpression of two components of the chaperone assisted selective autophagy (CASA) complex (BAG3 and HSPB8), enhanced ARpolyQ clearance, while the treatment with the mTOR independent autophagy activator trehalose induced complete ARpolyQ degradation. Thus, trehalose has beneficial effects in SBMA skeletal muscle models even when autophagy is impaired, possibly by stimulating CASA to assist the removal of ARpolyQ misfolded species/aggregates.
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Affiliation(s)
- Maria Elena Cicardi
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Riccardo Cristofani
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Valeria Crippa
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Veronica Ferrari
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Barbara Tedesco
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Elena Casarotto
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Marta Chierichetti
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Mariarita Galbiati
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Margherita Piccolella
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Elio Messi
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Serena Carra
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Centro Interdipartimentale di Neuroscienze e Neurotecnologie (CfNN), Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Maria Pennuto
- Department of Neurosciences, Neuromuscular Center, University of Padova, Padova, Italy
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Dulbecco Telethon Institute, Centre for Integrative Biology (CIBIO), University of Trento, Povo, Italy
| | - Paola Rusmini
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Angelo Poletti
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
- Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Milan, Italy
- *Correspondence: Angelo Poletti
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Querin G, Sorarù G, Pradat PF. Kennedy disease (X-linked recessive bulbospinal neuronopathy): A comprehensive review from pathophysiology to therapy. Rev Neurol (Paris) 2017; 173:326-337. [PMID: 28473226 DOI: 10.1016/j.neurol.2017.03.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/03/2017] [Accepted: 03/28/2017] [Indexed: 01/18/2023]
Abstract
Kennedy's disease, also known as spinal and bulbar muscular atrophy (SBMA), is a rare, adult-onset, X-linked recessive neuromuscular disease caused by expansion of a CAG repeat sequence in exon 1 of the androgen receptor gene (AR) encoding a polyglutamine (polyQ) tract. The polyQ-expanded AR accumulates in nuclei, and initiates degeneration and loss of motor neurons and dorsal root ganglia. While the disease has long been considered a pure lower motor neuron disease, recently, the presence of major hyper-creatine-kinase (CK)-emia and myopathic alterations on muscle biopsy has suggested the presence of a primary myopathy underlying a wide range of clinical manifestations. The disease, which affects male adults, is characterized by muscle weakness and atrophy localized proximally in the limbs, and bulbar involvement. Sensory disturbances are associated with the motor phenotype, but may be subclinical. The most frequent systemic symptom is gynecomastia related to androgen insensitivity, but other abnormalities, such as heart rhythm and urinary disturbances, have also been reported. The course of the disease is slowly progressive with normal life expectancy. The diagnosis of SBMA is based on genetic testing, with 38 CAG repeats taken as pathogenic. Despite several therapeutic attempts made in mouse models, no effective disease-modifying therapy is yet available, although symptomatic therapy is beneficial for the management of the weakness, fatigue and bulbar symptoms.
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Affiliation(s)
- G Querin
- Laboratoire d'imagerie biomédicale, Sorbonne universités, UPMC University Paris 06, CNRS, Inserm, 75013 Paris, France; Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - G Sorarù
- Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - P-F Pradat
- Laboratoire d'imagerie biomédicale, Sorbonne universités, UPMC University Paris 06, CNRS, Inserm, 75013 Paris, France; Département des maladies du système nerveux, hôpital Pitié-Salpêtriere, centre référent-SLA, AP-HP, 47-83, boulevard de l'Hôpital, 75013 Paris, France.
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6
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Poort JE, Rheuben MB, Breedlove SM, Jordan CL. Neuromuscular junctions are pathological but not denervated in two mouse models of spinal bulbar muscular atrophy. Hum Mol Genet 2016; 25:3768-3783. [PMID: 27493028 DOI: 10.1093/hmg/ddw222] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 06/15/2016] [Accepted: 07/04/2016] [Indexed: 12/21/2022] Open
Abstract
Spinal bulbar muscular atrophy (SBMA) is a progressive, late onset neuromuscular disease causing motor dysfunction in men. While the morphology of the neuromuscular junction (NMJ) is typically affected by neuromuscular disease, whether NMJs in SBMA are similarly affected by disease is not known. Such information will shed light on whether defective NMJs might contribute to the loss of motor function and represent a potential therapeutic target for treating symptoms of SBMA. To address this gap in information, the morphology of NMJs was examined in two mouse models of SBMA, a myogenic model that overexpresses wildtype androgen receptor (AR) exclusively in muscle fibres and a knockin (KI) model expressing a humanized mutant AR gene. The tripartite motor synapse consisting of motor nerve terminal, terminal Schwann cells (tSCs) and postsynaptic specialization were visualized and analysed using confocal microscopy. Counter to expectation, we found no evidence of denervation in either model, but junctions in both models show pathological fragmentation and an abnormal synaptophysin distribution consistent with functionally weak synapses. Neurofilament accumulations were observed only in the myogenic model, even though axonal transport dysfunction is characteristic of both models. The ultrastructure of NMJs revealed additional pathology, including deficits in docked vesicles presynaptically, wider synaptic clefts, and simpler secondary folds postsynaptically. The observed pathology of NMJs in diseased SBMA mice is likely the morphological correlates of defects in synaptic function which may underlie motor impairments associated with SBMA.
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Affiliation(s)
| | - Mary B Rheuben
- Neuroscience Program, Michigan State University, MI, USA
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Bott LC, Badders NM, Chen KL, Harmison GG, Bautista E, Shih CCY, Katsuno M, Sobue G, Taylor JP, Dantuma NP, Fischbeck KH, Rinaldi C. A small-molecule Nrf1 and Nrf2 activator mitigates polyglutamine toxicity in spinal and bulbar muscular atrophy. Hum Mol Genet 2016; 25:1979-1989. [PMID: 26962150 DOI: 10.1093/hmg/ddw073] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 02/29/2016] [Indexed: 11/12/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA, also known as Kennedy's disease) is one of nine neurodegenerative disorders that are caused by expansion of polyglutamine-encoding CAG repeats. Intracellular accumulation of abnormal proteins in these diseases, a pathological hallmark, is associated with defects in protein homeostasis. Enhancement of the cellular proteostasis capacity with small molecules has therefore emerged as a promising approach to treatment. Here, we characterize a novel curcumin analog, ASC-JM17, as an activator of central pathways controlling protein folding, degradation and oxidative stress resistance. ASC-JM17 acts on Nrf1, Nrf2 and Hsf1 to increase the expression of proteasome subunits, antioxidant enzymes and molecular chaperones. We show that ASC-JM17 ameliorates toxicity of the mutant androgen receptor (AR) responsible for SBMA in cell, fly and mouse models. Knockdown of the Drosophila Nrf1 and Nrf2 ortholog cap 'n' collar isoform-C, but not Hsf1, blocks the protective effect of ASC-JM17 on mutant AR-induced eye degeneration in flies. Our observations indicate that activation of the Nrf1/Nrf2 pathway is a viable option for pharmacological intervention in SBMA and potentially other polyglutamine diseases.
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Affiliation(s)
- Laura C Bott
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA, Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden,
| | - Nisha M Badders
- Department of Cell and Molecular Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Ke-Lian Chen
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - George G Harmison
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Elaine Bautista
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | | | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Nico P Dantuma
- Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Kenneth H Fischbeck
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Carlo Rinaldi
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
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Aberrant Autophagic Response in The Muscle of A Knock-in Mouse Model of Spinal and Bulbar Muscular Atrophy. Sci Rep 2015; 5:15174. [PMID: 26490709 PMCID: PMC4614888 DOI: 10.1038/srep15174] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/18/2015] [Indexed: 12/12/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is characterized by loss of motoneurons and sensory neurons, accompanied by atrophy of muscle cells. SBMA is due to an androgen receptor containing a polyglutamine tract (ARpolyQ) that misfolds and aggregates, thereby perturbing the protein quality control (PQC) system. Using SBMA AR113Q mice we analyzed proteotoxic stress-induced alterations of HSPB8-mediated PQC machinery promoting clearance of misfolded proteins by autophagy. In muscle of symptomatic AR113Q male mice, we found expression upregulation of Pax-7, myogenin, E2-ubiquitin ligase UBE2Q1 and acetylcholine receptor (AchR), but not of MyoD, and of two E3-ligases (MuRF-1 and Cullin3). TGFβ1 and PGC-1α were also robustly upregulated. We also found a dramatic perturbation of the autophagic response, with upregulation of most autophagic markers (Beclin-1, ATG10, p62/SQSTM1, LC3) and of the HSPB8-mediated PQC response. Both HSPB8 and its co-chaperone BAG3 were robustly upregulated together with other specific HSPB8 interactors (HSPB2 and HSPB3). Notably, the BAG3:BAG1 ratio increased in muscle suggesting preferential misfolded proteins routing to autophagy rather than to proteasome. Thus, mutant ARpolyQ induces a potent autophagic response in muscle cells. Alteration in HSPB8-based PQC machinery may represent muscle-specific biomarkers useful to assess SBMA progression in mice and patients in response to pharmacological treatments.
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9
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Oki K, Halievski K, Vicente L, Xu Y, Zeolla D, Poort J, Katsuno M, Adachi H, Sobue G, Wiseman RW, Breedlove SM, Jordan CL. Contractile dysfunction in muscle may underlie androgen-dependent motor dysfunction in spinal bulbar muscular atrophy. J Appl Physiol (1985) 2015; 118:941-52. [PMID: 25663674 DOI: 10.1152/japplphysiol.00886.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 02/03/2015] [Indexed: 01/11/2023] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is characterized by progressive muscle weakness linked to a polyglutamine expansion in the androgen receptor (AR). Current evidence indicates that mutant AR causes SBMA by acting in muscle to perturb its function. However, information about how muscle function is impaired is scant. One fundamental question is whether the intrinsic strength of muscles, an attribute of muscle independent of its mass, is affected. In the current study, we assess the contractile properties of hindlimb muscles in vitro from chronically diseased males of three different SBMA mouse models: a transgenic (Tg) model that broadly expresses a full-length human AR with 97 CAGs (97Q), a knock-in (KI) model that expresses a humanized AR containing a CAG expansion in the first exon, and a Tg myogenic model that overexpresses wild-type AR only in skeletal muscle fibers. We found that hindlimb muscles in the two Tg models (97Q and myogenic) showed marked losses in their intrinsic strength and resistance to fatigue, but were minimally affected in KI males. However, diseased muscles of all three models showed symptoms consistent with myotonic dystrophy type 1, namely, reduced resting membrane potential and deficits in chloride channel mRNA. These data indicate that muscle dysfunction is a core feature of SBMA caused by at least some of the same pathogenic mechanisms as myotonic dystrophy. Thus mechanisms controlling muscle function per se independent of mass are prime targets for SBMA therapeutics.
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Affiliation(s)
- Kentaro Oki
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | | | - Laura Vicente
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Youfen Xu
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Donald Zeolla
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Jessica Poort
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, Fukuoka, Japan; and
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Robert W Wiseman
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - S Marc Breedlove
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Cynthia L Jordan
- Neuroscience Program, Michigan State University, East Lansing, Michigan;
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10
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Giorgetti E, Rusmini P, Crippa V, Cristofani R, Boncoraglio A, Cicardi ME, Galbiati M, Poletti A. Synergic prodegradative activity of Bicalutamide and trehalose on the mutant androgen receptor responsible for spinal and bulbar muscular atrophy. Hum Mol Genet 2014; 24:64-75. [PMID: 25122660 PMCID: PMC4262493 DOI: 10.1093/hmg/ddu419] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an X-linked motoneuron disease due to a CAG triplet-repeat expansion in the androgen receptor (AR) gene, which is translated into an elongated polyglutamine (polyQ) tract in AR protein (ARpolyQ). ARpolyQ toxicity is activated by the AR ligand testosterone (or dihydrotestosterone), and the polyQ triggers ARpolyQ misfolding and aggregation in spinal cord motoneurons and muscle cells. In motoneurons, testosterone triggers nuclear toxicity by inducing AR nuclear translocation. Thus, (i) prevention of ARpolyQ nuclear localization, combined with (ii) an increased ARpolyQ cytoplasmic clearance, should reduce its detrimental activity. Using the antiandrogen Bicalutamide (Casodex®), which slows down AR activation and nuclear translocation, and the disaccharide trehalose, an autophagy activator, we found that, in motoneurons, the two compounds together reduced ARpolyQ insoluble forms with higher efficiency than that obtained with single treatments. The ARpolyQ clearance was mediated by trehalose-induced autophagy combined with the longer cytoplasmic retention of ARpolyQ bound to Bicalutamide. This allows an increased recognition of misfolded species by the autophagic system prior to their migration into the nucleus. Interestingly, the combinatory use of trehalose and Bicalutamide was also efficient in the removal of insoluble species of AR with a very long polyQ (Q112) tract, which typically aggregates into the cell nuclei. Collectively, these data suggest that the combinatory use of Bicalutamide and trehalose is a novel approach to facilitate ARpolyQ clearance that has to be tested in other cell types target of SBMA (i.e. muscle cells) and in vivo in animal models of SBMA.
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Affiliation(s)
- Elisa Giorgetti
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA and
| | - Paola Rusmini
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy
| | - Valeria Crippa
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy
| | - Riccardo Cristofani
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy
| | - Alessandra Boncoraglio
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy Department of Cell Biology, University Medical Center of Groningen, RB 9700 Groningen, The Netherlands
| | - Maria E Cicardi
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy
| | - Mariarita Galbiati
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy
| | - Angelo Poletti
- Sezione di Biomedicina ed Endocrinologia, Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milano 20133, Italy Centro InterUniversitario sulle Malattie Neurodegenerative, Università degli Studi di Firenze, Genova e Roma Tor Vergata, Milano 20133, Italy
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11
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Peripheral androgen receptor gene suppression rescues disease in mouse models of spinal and bulbar muscular atrophy. Cell Rep 2014; 7:774-84. [PMID: 24746732 DOI: 10.1016/j.celrep.2014.02.008] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 01/10/2014] [Accepted: 02/05/2014] [Indexed: 02/07/2023] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is caused by the polyglutamine androgen receptor (polyQ-AR), a protein expressed by both lower motor neurons and skeletal muscle. Although viewed as a motor neuronopathy, data from patients and mouse models suggest that muscle contributes to disease pathogenesis. Here, we tested this hypothesis using AR113Q knockin and human bacterial artificial chromosome/clone (BAC) transgenic mice that express the full-length polyQ-AR and display androgen-dependent weakness, muscle atrophy, and early death. We developed antisense oligonucleotides that suppressed AR gene expression in the periphery but not the CNS after subcutaneous administration. Suppression of polyQ-AR in the periphery rescued deficits in muscle weight, fiber size, and grip strength, reversed changes in muscle gene expression, and extended the lifespan of mutant males. We conclude that polyQ-AR expression in the periphery is an important contributor to pathology in SBMA mice and that peripheral administration of therapeutics should be explored for SBMA patients.
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12
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Boyer JG, Ferrier A, Kothary R. More than a bystander: the contributions of intrinsic skeletal muscle defects in motor neuron diseases. Front Physiol 2013; 4:356. [PMID: 24391590 PMCID: PMC3866803 DOI: 10.3389/fphys.2013.00356] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 11/20/2013] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and spinal-bulbar muscular atrophy (SBMA) are devastating diseases characterized by the degeneration of motor neurons. Although the molecular causes underlying these diseases differ, recent findings have highlighted the contribution of intrinsic skeletal muscle defects in motor neuron diseases. The use of cell culture and animal models has led to the important finding that muscle defects occur prior to and independently of motor neuron degeneration in motor neuron diseases. In SMA for instance, the muscle specific requirements of the SMA disease-causing gene have been demonstrated by a series of genetic rescue experiments in SMA models. Conditional ALS mouse models expressing a muscle specific mutant SOD1 gene develop atrophy and muscle degeneration in the absence of motor neuron pathology. Treating SBMA mice by over-expressing IGF-1 in a skeletal muscle-specific manner attenuates disease severity and improves motor neuron pathology. In the present review, we provide an in depth description of muscle intrinsic defects, and discuss how they impact muscle function in these diseases. Furthermore, we discuss muscle-specific therapeutic strategies used to treat animal models of SMA, ALS, and SBMA. The study of intrinsic skeletal muscle defects is crucial for the understanding of the pathophysiology of these diseases and will open new therapeutic options for the treatment of motor neuron diseases.
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Affiliation(s)
- Justin G Boyer
- Ottawa Hospital Research Institute, Regenerative Medicine Program Ottawa ON, Canada ; Department of Cellular and Molecular Medicine, University of Ottawa Ottawa, ON, Canada
| | - Andrew Ferrier
- Ottawa Hospital Research Institute, Regenerative Medicine Program Ottawa ON, Canada ; Department of Cellular and Molecular Medicine, University of Ottawa Ottawa, ON, Canada
| | - Rashmi Kothary
- Ottawa Hospital Research Institute, Regenerative Medicine Program Ottawa ON, Canada ; Department of Cellular and Molecular Medicine, University of Ottawa Ottawa, ON, Canada ; Department of Medicine, University of Ottawa Ottawa, ON, Canada
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13
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Chua JP, Lieberman AP. Pathogenic mechanisms and therapeutic strategies in spinobulbar muscular atrophy. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2013; 12:1146-1156. [PMID: 24040817 PMCID: PMC4003563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 07/10/2012] [Accepted: 07/10/2012] [Indexed: 06/02/2023]
Abstract
We review the genetic and clinical features of spinobulbar muscular atrophy (SBMA), a progressive neuromuscular disorder caused by a CAG/glutamine tract expansion in the androgen receptor. SBMA was the first polyglutamine disease to be discovered, and we compare and contrast it with related degenerative disorders of the nervous system caused by expanded glutamine tracts. We review the cellular and animals models that have been most widely used to study this disorder, and highlight insights into disease pathogenesis derived from this work. These model systems have revealed critical aspects of the disease, including its hormone dependence, a feature that underlies disease occurrence only in men with the mutant allele. We discuss how this and other findings have been translated to clinical trials for SBMA patients, and examine emerging therapeutic targets that have been identified by recent work.
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Affiliation(s)
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, 3510 MSRB1, 1150 W. Medical Center Dr., Ann Arbor, Michigan 48109-0605, USA.
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14
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Malena A, Pennuto M, Tezze C, Querin G, D’Ascenzo C, Silani V, Cenacchi G, Scaramozza A, Romito S, Morandi L, Pegoraro E, Russell AP, Sorarù G, Vergani L. Androgen-dependent impairment of myogenesis in spinal and bulbar muscular atrophy. Acta Neuropathol 2013; 126:109-21. [PMID: 23644820 DOI: 10.1007/s00401-013-1122-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 04/15/2013] [Accepted: 04/25/2013] [Indexed: 01/05/2023]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an inherited neuromuscular disease caused by expansion of a polyglutamine (polyQ) tract in the androgen receptor (AR). SBMA is triggered by the interaction between polyQ-AR and its natural ligands, testosterone and dihydrotestosterone (DHT). SBMA is characterized by the loss of lower motor neurons and skeletal muscle fasciculations, weakness, and atrophy. To test the hypothesis that the interaction between polyQ-AR and androgens exerts cell-autonomous toxicity in skeletal muscle, we characterized the process of myogenesis and polyQ-AR expression in DHT-treated satellite cells obtained from SBMA patients and age-matched healthy control subjects. Treatment with androgens increased the size and number of myonuclei in myotubes from control subjects, but not from SBMA patients. Myotubes from SBMA patients had a reduced number of nuclei, suggesting impaired myotube fusion and altered contractile structures. The lack of anabolic effects of androgens on myotubes from SBMA patients was not due to defects in myoblast proliferation, differentiation or apoptosis. DHT treatment of myotubes from SBMA patients increased nuclear accumulation of polyQ-AR and decreased the expression of interleukin-4 (IL-4) when compared to myotubes from control subjects. Following DHT treatment, exposure of myotubes from SBMA patients with IL-4 treatment rescued myonuclear number and size to control levels. This supports the hypothesis that androgens alter the fusion process in SBMA myogenesis. In conclusion, these results provide evidence of an androgen-dependent impairment of myogenesis in SBMA that could contribute to disease pathogenesis.
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15
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Beitel LK, Alvarado C, Mokhtar S, Paliouras M, Trifiro M. Mechanisms mediating spinal and bulbar muscular atrophy: investigations into polyglutamine-expanded androgen receptor function and dysfunction. Front Neurol 2013; 4:53. [PMID: 23720649 PMCID: PMC3654311 DOI: 10.3389/fneur.2013.00053] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 04/26/2013] [Indexed: 11/13/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA, Kennedy’s disease), a late-onset neuromuscular disorder, is caused by expansion of the polymorphic polyglutamine tract in the androgen receptor (AR). The AR is a ligand-activated transcription factor, but plays roles in other cellular pathways. In SBMA, selective motor neuron degeneration occurs in the brainstem and spinal cord, thus the causes of neuronal dysfunction have been studied. However, pathogenic pathways in muscles may also be involved. Cultured cells, fly and mouse models are used to study the molecular mechanisms leading to SBMA. Both the structure of the polyglutamine-expanded AR (polyQ AR) and its interactions with other proteins are altered relative to the normal AR. The ligand-dependent translocation of the polyQ AR to the nucleus appears to be critical, as are interdomain interactions. The polyQ AR, or fragments thereof, can form nuclear inclusions, but their pathogenic or protective nature is unclear. Other data suggests soluble polyQ AR oligomers can be harmful. Post-translational modifications such as phosphorylation, acetylation, and ubiquitination influence AR function and modulate the deleterious effects of the polyQ AR. Transcriptional dysregulation is highly likely to be a factor in SBMA; deregulation of non-genomic AR signaling may also be involved. Studies on polyQ AR-protein degradation suggest inhibition of the ubiquitin proteasome system and changes to autophagic pathways may be relevant. Mitochondrial function and axonal transport may also be affected by the polyQ AR. Androgens, acting through the AR, can be neurotrophic and are important in muscle development; hence both loss of normal AR functions and gain of novel harmful functions by the polyQ AR can contribute to neurodegeneration and muscular atrophy. Thus investigations into polyQ AR function have shown that multiple complex mechanisms lead to the initiation and progression of SBMA.
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Affiliation(s)
- Lenore K Beitel
- Lady Davis Institute for Medical Research, Jewish General Hospital Montreal, QC, Canada ; Department of Medicine, McGill University Montreal, QC, Canada ; Department of Human Genetics, McGill University Montreal, QC, Canada
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16
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Sicot G, Gomes-Pereira M. RNA toxicity in human disease and animal models: from the uncovering of a new mechanism to the development of promising therapies. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1390-409. [PMID: 23500957 DOI: 10.1016/j.bbadis.2013.03.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/01/2013] [Accepted: 03/04/2013] [Indexed: 01/06/2023]
Abstract
Mutant ribonucleic acid (RNA) molecules can be toxic to the cell, causing human disease through trans-acting dominant mechanisms. RNA toxicity was first described in myotonic dystrophy type 1, a multisystemic disorder caused by the abnormal expansion of a non-coding trinucleotide repeat sequence. The development of multiple and complementary animal models of disease has greatly contributed to clarifying the complex disease pathways mediated by toxic RNA molecules. RNA toxicity is not limited to myotonic dystrophy and spreads to an increasing number of human conditions, which share some unifying pathogenic events mediated by toxic RNA accumulation and disruption of RNA-binding proteins. The remarkable progress in the dissection of disease pathobiology resulted in the rational design of molecular therapies, which have been successfully tested in animal models. Toxic RNA diseases, and in particular myotonic dystrophy, clearly illustrate the critical contribution of animal models of disease in translational research: from gene mutation to disease mechanisms, and ultimately to therapy development. This article is part of a Special Issue entitled: Animal Models of Disease.
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17
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Wang AM, Miyata Y, Klinedinst S, Peng HM, Chua JP, Komiyama T, Li X, Morishima Y, Merry DE, Pratt WB, Osawa Y, Collins CA, Gestwicki JE, Lieberman AP. Activation of Hsp70 reduces neurotoxicity by promoting polyglutamine protein degradation. Nat Chem Biol 2013; 9:112-8. [PMID: 23222885 PMCID: PMC3552084 DOI: 10.1038/nchembio.1140] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 11/09/2012] [Indexed: 12/21/2022]
Abstract
We sought new strategies to reduce amounts of the polyglutamine androgen receptor (polyQ AR) and achieve benefits in models of spinobulbar muscular atrophy, a protein aggregation neurodegenerative disorder. Proteostasis of the polyQ AR is controlled by the heat shock protein 90 (Hsp90)- and Hsp70-based chaperone machinery, but mechanisms regulating the protein's turnover are incompletely understood. We demonstrate that overexpression of Hsp70 interacting protein (Hip), a co-chaperone that enhances binding of Hsp70 to its substrates, promotes client protein ubiquitination and polyQ AR clearance. Furthermore, we identify a small molecule that acts similarly to Hip by allosterically promoting Hsp70 binding to unfolded substrates. Like Hip, this synthetic co-chaperone enhances client protein ubiquitination and polyQ AR degradation. Both genetic and pharmacologic approaches targeting Hsp70 alleviate toxicity in a Drosophila model of spinobulbar muscular atrophy. These findings highlight the therapeutic potential of allosteric regulators of Hsp70 and provide new insights into the role of the chaperone machinery in protein quality control.
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Affiliation(s)
- Adrienne M. Wang
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Neuroscience Graduate Program, The University of Michigan, Ann Arbor, MI 48109
| | - Yoshinari Miyata
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Life Sciences Institute, The University of Michigan, Ann Arbor, MI 48109
| | - Susan Klinedinst
- Molecular, Cellular, and Developmental Biology, The University of Michigan, Ann Arbor, MI 48109
| | - Hwei-Ming Peng
- Department of Pharmacology, The University of Michigan, Ann Arbor, MI 48109
| | - Jason P. Chua
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Neuroscience Graduate Program, The University of Michigan, Ann Arbor, MI 48109
- Medical Scientist Training Program, The University of Michigan, Ann Arbor, MI 48109
| | - Tomoko Komiyama
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Life Sciences Institute, The University of Michigan, Ann Arbor, MI 48109
| | - Xiaokai Li
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Life Sciences Institute, The University of Michigan, Ann Arbor, MI 48109
| | | | - Diane E. Merry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - William B. Pratt
- Department of Pharmacology, The University of Michigan, Ann Arbor, MI 48109
| | - Yoichi Osawa
- Department of Pharmacology, The University of Michigan, Ann Arbor, MI 48109
| | - Catherine A. Collins
- Molecular, Cellular, and Developmental Biology, The University of Michigan, Ann Arbor, MI 48109
| | - Jason E. Gestwicki
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Life Sciences Institute, The University of Michigan, Ann Arbor, MI 48109
| | - Andrew P. Lieberman
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109
- Neuroscience Graduate Program, The University of Michigan, Ann Arbor, MI 48109
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18
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Vlasova-St Louis I, Dickson AM, Bohjanen PR, Wilusz CJ. CELFish ways to modulate mRNA decay. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:695-707. [PMID: 23328451 DOI: 10.1016/j.bbagrm.2013.01.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/03/2013] [Accepted: 01/05/2013] [Indexed: 12/14/2022]
Abstract
The CELF family of RNA-binding proteins regulates many steps of mRNA metabolism. Although their best characterized function is in pre-mRNA splice site choice, CELF family members are also powerful modulators of mRNA decay. In this review we focus on the different modes of regulation that CELF proteins employ to mediate mRNA decay by binding to GU-rich elements. After starting with an overview of the importance of CELF proteins during development and disease pathogenesis, we then review the mRNA networks and cellular pathways these proteins regulate and the mechanisms by which they influence mRNA decay. Finally, we discuss how CELF protein activity is modulated during development and in response to cellular signals. We conclude by highlighting the priorities for new experiments in this field. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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19
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Katsuno M, Tanaka F, Adachi H, Banno H, Suzuki K, Watanabe H, Sobue G. Pathogenesis and therapy of spinal and bulbar muscular atrophy (SBMA). Prog Neurobiol 2012; 99:246-56. [PMID: 22609045 DOI: 10.1016/j.pneurobio.2012.05.007] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/24/2012] [Accepted: 05/08/2012] [Indexed: 01/18/2023]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a late-onset motor neuron disease characterized by slowly progressive muscle weakness and atrophy. During the last two decades, basic and clinical research has provided important insights into the disease phenotype and pathophysiology. The cause of SBMA is the expansion of a trinucleotide CAG repeat encoding a polyglutamine tract within the first exon of the androgen receptor (AR) gene. SBMA exclusively affects adult males, whereas females homozygous for the AR mutation do not manifest neurological symptoms. The ligand-dependent nuclear accumulation of the polyglutamine-expanded AR protein is central to the gender-specific pathogenesis of SBMA, although additional steps, e.g., DNA binding, inter-domain interactions, and post-translational modification of AR, modify toxicity. The interactions with co-regulators are another requisite for the toxic properties of the polyglutamine-expanded AR. It is also shown that the polyglutamine-expanded AR induces diverse molecular events, such as transcriptional dysregulation, axonal transport disruption, and mitochondrial dysfunction, which play causative roles in the neurodegeneration in SBMA. The pathogenic AR-induced myopathy also contributes to the non-cell autonomous degeneration of motor neurons. Pre-clinical studies using animal models show that the pathogenic AR-mediated neurodegeneration is suppressed by androgen inactivation, the efficacy of which has been tested in clinical trials. Pharmacological activation of cellular defense machineries, such as molecular chaperones, ubiquitin-proteasome system, and autophagy, also exerts neuroprotective effects in experimental models of SBMA.
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Affiliation(s)
- Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
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20
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Sambataro F, Pennuto M. Cell-autonomous and non-cell-autonomous toxicity in polyglutamine diseases. Prog Neurobiol 2012; 97:152-72. [DOI: 10.1016/j.pneurobio.2011.10.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 10/21/2011] [Accepted: 10/26/2011] [Indexed: 12/21/2022]
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21
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Robins DM. Androgen receptor gene polymorphisms and alterations in prostate cancer: of humanized mice and men. Mol Cell Endocrinol 2012; 352:26-33. [PMID: 21689727 PMCID: PMC3188356 DOI: 10.1016/j.mce.2011.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 05/18/2011] [Accepted: 06/03/2011] [Indexed: 11/26/2022]
Abstract
Germline polymorphisms and somatic mutations of the androgen receptor (AR) have been intensely investigated in prostate cancer but even with genomic approaches their impact remains controversial. To assess the functional significance of AR genetic variation, we converted the mouse gene to the human sequence by germline recombination and engineered alleles to query the role of a polymorphic glutamine (Q) tract implicated in cancer risk. In a prostate cancer model, AR Q tract length influences progression and castration response. Mutation profiling in mice provides direct evidence that somatic AR variants are selected by therapy, a finding validated in human metastases from distinct treatment groups. Mutant ARs exploit multiple mechanisms to resist hormone ablation, including alterations in ligand specificity, target gene selectivity, chaperone interaction and nuclear localization. Regardless of their frequency, these variants permute normal function to reveal novel means to target wild type AR and its key interacting partners.
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Affiliation(s)
- Diane M Robins
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109-5618, USA.
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22
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Kumar A, Parkesh R, Sznajder LJ, Childs-Disney JL, Sobczak K, Disney MD. Chemical correction of pre-mRNA splicing defects associated with sequestration of muscleblind-like 1 protein by expanded r(CAG)-containing transcripts. ACS Chem Biol 2012; 7:496-505. [PMID: 22252896 DOI: 10.1021/cb200413a] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recently, it was reported that expanded r(CAG) triplet repeats (r(CAG)(exp)) associated with untreatable neurological diseases cause pre-mRNA mis-splicing likely due to sequestration of muscleblind-like 1 (MBNL1) splicing factor. Bioactive small molecules that bind the 5'CAG/3'GAC motif found in r(CAG)(exp) hairpin structure were identified by using RNA binding studies and virtual screening/chemical similarity searching. Specifically, a benzylguanidine-containing small molecule was found to improve pre-mRNA alternative splicing of MBNL1-sensitive exons in cells expressing the toxic r(CAG)(exp). The compound was identified by first studying the binding of RNA 1 × 1 nucleotide internal loops to small molecules known to have affinity for nucleic acids. Those studies identified 4',6-diamidino-2-phenylindole (DAPI) as a specific binder to RNAs with the 5'CAG/3'GAC motif. DAPI was then used as a query molecule in a shape- and chemistry alignment-based virtual screen to identify compounds with improved properties, which identified 4-guanidinophenyl 4-guanidinobenzoate, a small molecule that improves pre-mRNA splicing defects associated with the r(CAG)(exp)-MBNL1 complex. This compound may facilitate the development of therapeutics to treat diseases caused by r(CAG)(exp) and could serve as a useful chemical tool to dissect the mechanisms of r(CAG)(exp) toxicity. The approach used in these studies, defining the small RNA motifs that bind small molecules with known affinity for nucleic acids and then using virtual screening to optimize them for bioactivity, may be generally applicable for designing small molecules that target other RNAs in the human genomic sequence.
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Affiliation(s)
- Amit Kumar
- Department
of Chemistry, The Scripps Research Institute, Scripps Florida, 130
Scripps Way 3A1, Jupiter, Florida 33458, United States
| | - Raman Parkesh
- Department
of Chemistry, The Scripps Research Institute, Scripps Florida, 130
Scripps Way 3A1, Jupiter, Florida 33458, United States
| | - Lukasz J. Sznajder
- Department of Gene Expression,
Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan,
Poland
| | - Jessica L. Childs-Disney
- Department
of Chemistry, The Scripps Research Institute, Scripps Florida, 130
Scripps Way 3A1, Jupiter, Florida 33458, United States
| | - Krzysztof Sobczak
- Department of Gene Expression,
Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan,
Poland
| | - Matthew D. Disney
- Department
of Chemistry, The Scripps Research Institute, Scripps Florida, 130
Scripps Way 3A1, Jupiter, Florida 33458, United States
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Yu Z, Wang AM, Adachi H, Katsuno M, Sobue G, Yue Z, Robins DM, Lieberman AP. Macroautophagy is regulated by the UPR-mediator CHOP and accentuates the phenotype of SBMA mice. PLoS Genet 2011; 7:e1002321. [PMID: 22022281 PMCID: PMC3192827 DOI: 10.1371/journal.pgen.1002321] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 08/10/2011] [Indexed: 12/11/2022] Open
Abstract
Altered protein homeostasis underlies degenerative diseases triggered by misfolded proteins, including spinal and bulbar muscular atrophy (SBMA), a neuromuscular disorder caused by a CAG/glutamine expansion in the androgen receptor. Here we show that the unfolded protein response (UPR), an ER protein quality control pathway, is induced in skeletal muscle from SBMA patients, AR113Q knock-in male mice, and surgically denervated wild-type mice. To probe the consequence of UPR induction, we deleted CHOP (C/EBP homologous protein), a transcription factor induced following ER stress. CHOP deficiency accentuated atrophy in both AR113Q and surgically denervated muscle through activation of macroautophagy, a lysosomal protein quality control pathway. Conversely, impaired autophagy due to Beclin-1 haploinsufficiency decreased muscle wasting and extended lifespan of AR113Q males, producing a significant and unexpected amelioration of the disease phenotype. Our findings highlight critical cross-talk between the UPR and macroautophagy, and they indicate that autophagy activation accentuates aspects of the SBMA phenotype. In many age-dependent neurodegenerative diseases, the accumulation of misfolded or mutant proteins drives pathogenesis. Several protein quality control pathways have emerged as central regulators of the turnover of these toxic proteins and therefore impact phenotypic severity. In spinal and bulbar muscular atrophy (SBMA), the mutant androgen receptor with an expanded glutamine tract undergoes hormone-dependent nuclear translocation, unfolding, and oligomerization—steps that are critical to the development of progressive proximal limb and bulbar muscle weakness in men. Here we show that the unfolded protein response (UPR), an endoplasmic reticulum stress response, is triggered in skeletal muscle from SBMA patients and knock-in mice. We find that disruption of the UPR exacerbates skeletal muscle atrophy through the induction of macroautophagy, a lysosomal protein quality pathway. In contrast, impaired autophagy diminishes muscle wasting and prolongs lifespan of SBMA mice. Our findings highlight cross-talk between the UPR and autophagy, and they suggest that limited activation of the autophagic pathway may be beneficial in certain neuromuscular diseases such as SBMA where the nucleus is the essential site of toxicity.
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Affiliation(s)
- Zhigang Yu
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Adrienne M. Wang
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Neuroscience Graduate Program, The University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Hiroaki Adachi
- Department of Neurology, Nagoya University, Nagoya, Japan
| | | | - Gen Sobue
- Department of Neurology, Nagoya University, Nagoya, Japan
| | - Zhenyu Yue
- Departments of Neurology and Neuroscience, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Diane M. Robins
- Department of Human Genetics, The University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Andrew P. Lieberman
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Neuroscience Graduate Program, The University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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Apponi LH, Corbett AH, Pavlath GK. RNA-binding proteins and gene regulation in myogenesis. Trends Pharmacol Sci 2011; 32:652-8. [PMID: 21982546 DOI: 10.1016/j.tips.2011.06.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 06/03/2011] [Accepted: 06/17/2011] [Indexed: 11/17/2022]
Abstract
Skeletal muscle development, repair and function are dependent on highly coordinated expression of many genes. RNA-binding proteins are crucial determinants of gene expression in the health and disease of various tissues, including skeletal muscle. A variety of RNA-binding proteins are associated with a transcript during its life cycle and define the lifetime, cellular localization, processing and rate at which that transcript is translated and ultimately degraded. The focus of this review is to highlight the roles of the best-characterized RNA-binding proteins in muscle, including HuR, KSRP, CUGBP1, PABPN1, Lin-28 and TTP. Recent studies indicate key functions for these RNA-binding proteins in different aspects of muscle physiology. Understanding the role of specific RNA-binding proteins in skeletal muscle will provide insights not only into basic mechanisms regulating gene expression in muscle, but also into the etiology and pathology of muscle disease.
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Affiliation(s)
- Luciano H Apponi
- Department of Pharmacology, Emory University, Atlanta, GA 30322, USA
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25
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Mykowska A, Sobczak K, Wojciechowska M, Kozlowski P, Krzyzosiak WJ. CAG repeats mimic CUG repeats in the misregulation of alternative splicing. Nucleic Acids Res 2011; 39:8938-51. [PMID: 21795378 PMCID: PMC3203611 DOI: 10.1093/nar/gkr608] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Mutant transcripts containing expanded CUG repeats in the untranslated region are a pathogenic factor in myotonic dystrophy type 1 (DM1). The mutant RNA sequesters the muscleblind-like 1 (MBNL1) splicing factor and causes misregulation of the alternative splicing of multiple genes that are linked to clinical symptoms of the disease. In this study, we show that either long untranslated CAG repeat RNA or short synthetic CAG repeats induce splicing aberrations typical of DM1. Alternative splicing defects are also caused by translated CAG repeats in normal cells transfected with a mutant ATXN3 gene construct and in cells derived from spinocerebellar ataxia type 3 and Huntington's disease patients. Splicing misregulation is unlikely to be caused by traces of antisense transcripts with CUG repeats, and the possible trigger of this misregulation may be sequestration of the MBNL1 protein with nuclear RNA inclusions containing expanded CAG repeat transcripts. We propose that alternative splicing misregulation by mutant CAG repeats may contribute to the pathological features of polyglutamine disorders.
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Affiliation(s)
- Agnieszka Mykowska
- Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704 Poznan, Poland
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26
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Gomes-Pereira M, Cooper TA, Gourdon G. Myotonic dystrophy mouse models: towards rational therapy development. Trends Mol Med 2011; 17:506-17. [PMID: 21724467 DOI: 10.1016/j.molmed.2011.05.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 05/04/2011] [Accepted: 05/17/2011] [Indexed: 01/26/2023]
Abstract
DNA repeat expansions can result in the production of toxic RNA. RNA toxicity has been best characterised in the context of myotonic dystrophy. Nearly 20 mouse models have contributed significant and complementary insights into specific aspects of this novel disease mechanism. These models provide a unique resource to test pharmacological, anti-sense, and gene-therapy therapeutic strategies that target specific events of the pathobiological cascade. Further proof-of-principle concept studies and preclinical experiments require critical and thorough analysis of the multiple myotonic dystrophy transgenic lines available. This review provides in-depth assessment of the molecular and phenotypic features of these models and their contribution towards the dissection of disease mechanisms, and compares them with the human condition. More importantly, it provides critical assessment of their suitability and limitations for preclinical testing of emerging therapeutic strategies.
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Affiliation(s)
- Mário Gomes-Pereira
- Inserm U781, Université Paris Descartes, Faculté de Medicine Necker Enfants Malades, Paris, France.
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27
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Orengo JP, Ward AJ, Cooper TA. Alternative splicing dysregulation secondary to skeletal muscle regeneration. Ann Neurol 2011; 69:681-90. [PMID: 21400563 DOI: 10.1002/ana.22278] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 09/06/2010] [Accepted: 09/17/2010] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Dysregulation of alternative splicing has become a molecular hallmark of myotonic dystrophy type 1 (DM1), in which neonatal splice variants are expressed in adult skeletal muscle. Splicing dysregulation is induced by RNA containing expanded CUG repeats expressed from the expanded mutant allele by sequestration of muscleblindlike 1 (MBNL1) protein within nuclear RNA foci and increased CUGBP, ELAV-like family member 1 (CELF1) protein levels. Dysregulated splicing has also been identified in other neuromuscular disorders, suggesting either that diseases with different molecular causes share a common pathogenic mechanism or that dysregulated splicing can also be a common secondary consequence of muscle degeneration and regeneration. METHODS In this study, we examined regulation of alternative splicing in 4 different mouse models of muscular dystrophy, including DM1, limb-girdle muscular dystrophy, congenital merosin-deficient muscular dystrophy, and Duchenne muscular dystrophy, and 2 myotoxin (cardiotoxin and notexin) muscle injury models. RESULTS We show that DM1-like alternative splicing dysregulation and altered expression of MBNL1 and CELF1 occur in non-DM1 mouse models of muscular dystrophy and muscle injury, most likely due to recapitulation of neonatal splicing patterns in regenerating fibers. In contrast, CELF1 was elevated in nuclei of mature myofibers of the DM1 model, consistent with a primary effect of pathogenic RNA expression. INTERPRETATION Splicing dysregulation in DM1 is a primary effect of RNA containing expanded CUG repeats. However, we conclude that splicing changes can also be observed secondary to muscle regeneration, and this possibility must be taken into account when evaluating cause-effect relationships between dysregulated splicing and disease processes.
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Affiliation(s)
- James P Orengo
- Department of Pathology and Immunology and, Baylor College of Medicine Houston, TX 77030, USA
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28
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Systematic analysis of cis-elements in unstable mRNAs demonstrates that CUGBP1 is a key regulator of mRNA decay in muscle cells. PLoS One 2010; 5:e11201. [PMID: 20574513 PMCID: PMC2888570 DOI: 10.1371/journal.pone.0011201] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 05/27/2010] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Dramatic changes in gene expression occur in response to extracellular stimuli and during differentiation. Although transcriptional effects are important, alterations in mRNA decay also play a major role in achieving rapid and massive changes in mRNA abundance. Moreover, just as transcription factor activity varies between different cell types, the factors influencing mRNA decay are also cell-type specific. PRINCIPAL FINDINGS We have established the rates of decay for over 7000 transcripts expressed in mouse C2C12 myoblasts. We found that GU-rich (GRE) and AU-rich (ARE) elements are over-represented in the 3'UTRs of short-lived mRNAs and that these mRNAs tend to encode factors involved in cell cycle and transcription regulation. Stabilizing elements were also identified. By comparing mRNA decay rates in C2C12 cells with those previously measured for pluripotent and differentiating embryonic stem (ES) cells, we identified several groups of transcripts that exhibit cell-type specific decay rates. Further, whereas in C2C12 cells the impact of GREs on mRNA decay appears to be greater than that of AREs, AREs are more significant in ES cells, supporting the idea that cis elements make a cell-specific contribution to mRNA stability. GREs are recognized by CUGBP1, an RNA-binding protein and instability factor whose function is affected in several neuromuscular diseases. We therefore utilized RNA immunoprecipitation followed by microarray (RIP-Chip) to identify CUGBP1-associated transcripts. These mRNAs also showed dramatic enrichment of GREs in their 3'UTRs and encode proteins linked with cell cycle, and intracellular transport. Interestingly several CUGBP1 substrate mRNAs, including those encoding the myogenic transcription factors Myod1 and Myog, are also bound by the stabilizing factor HuR in C2C12 cells. Finally, we show that several CUGBP1-associated mRNAs containing 3'UTR GREs, including Myod1, are stabilized in cells depleted of CUGBP1, consistent with the role of CUGBP1 as a destabilizing factor. CONCLUSIONS Taken together, our results systematically establish cis-acting determinants of mRNA decay rates in C2C12 myoblast cells and demonstrate that CUGBP1 associates with GREs to regulate decay of a wide range of mRNAs including several that are critical for muscle development.
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Dickson AM, Wilusz CJ. Repeat expansion diseases: when a good RNA turns bad. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:173-92. [PMID: 21956913 DOI: 10.1002/wrna.18] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An increasing number of dominantly inherited diseases have now been linked with expansion of short repeats within specific genes. Although some of these expansions affect protein function or result in haploinsufficiency, a significant portion cause pathogenesis through production of toxic RNA molecules that alter cellular metabolism. In this review, we examine the criteria that influence toxicity of these mutant RNAs and discuss new developments in therapeutic approaches.
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Affiliation(s)
- Alexa M Dickson
- Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO 80523, USA
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Abstract
The production of functional spermatozoa is a complex process requiring the coordinated expression of thousands of genes. It is likely that the intricate nature of these interactions contributes to the large number of idiopathic male infertility cases seen in humans. Conversely, the complexity of the highly regulated and interconnected processes of spermatogenesis and posttesticular sperm maturation events offers opportunities for the development of male-based contraceptive targets. The recent advances in genetic manipulation technologies and the completion of the human and mouse genome sequencing programs have provided scientists with sophisticated ways to generate mouse models for the study of basic biological mechanisms, in order to understand disease pathology and develop novel therapeutic approaches. The three common types of mouse model used for medical research are transgenic, knockout/knockin, and chemical-induced point mutant mice. Each type has relative strengths and weaknesses with respect to its fidelity to the disease processes in humans. In this chapter, we focus on the utility of the different types of mouse model in obtaining a better understanding of the mechanisms that control spermatogenesis and developing male-based contraceptive regimens.
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