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Mangiamele LA, Dawn A, LeCure KM, Mantica GE, Racicot R, Fuxjager MJ, Preininger D. How new communication behaviors evolve: Androgens as modifiers of neuromotor structure and function in foot-flagging frogs. Horm Behav 2024; 161:105502. [PMID: 38382227 DOI: 10.1016/j.yhbeh.2024.105502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/08/2023] [Accepted: 02/05/2024] [Indexed: 02/23/2024]
Abstract
How diverse animal communication signals have arisen is a question that has fascinated many. Xenopus frogs have been a model system used for three decades to reveal insights into the neuroendocrine mechanisms and evolution of vocal diversity. Due to the ease of studying central nervous system control of the laryngeal muscles in vitro, Xenopus has helped us understand how variation in vocal communication signals between sexes and between species is produced at the molecular, cellular, and systems levels. Yet, it is becoming easier to make similar advances in non-model organisms. In this paper, we summarize our research on a group of frog species that have evolved a novel hind limb signal known as 'foot flagging.' We have previously shown that foot flagging is androgen dependent and that the evolution of foot flagging in multiple unrelated species is accompanied by the evolution of higher androgen hormone sensitivity in the leg muscles. Here, we present new preliminary data that compare patterns of androgen receptor expression and neuronal cell density in the lumbar spinal cord - the neuromotor system that controls the hind limb - between foot-flagging and non-foot-flagging frog species. We then relate our work to prior findings in Xenopus, highlighting which patterns of hormone sensitivity and neuroanatomical structure are shared between the neuromotor systems underlying Xenopus vocalizations and foot-flagging frogs' limb movement and which appear to be species-specific. Overall, we aim to illustrate the power of drawing inspiration from experiments in model organisms, in which the mechanistic details have been worked out, and then applying these ideas to a non-model species to reveal new details, further complexities, and fresh hypotheses.
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Affiliation(s)
- Lisa A Mangiamele
- Department of Biological Sciences, Smith College, Northampton, MA 01063, United States of America.
| | - AllexAndrya Dawn
- Department of Biological Sciences, Smith College, Northampton, MA 01063, United States of America
| | - Kerry M LeCure
- Department of Biological Sciences, Smith College, Northampton, MA 01063, United States of America
| | - Gina E Mantica
- Department of Biological Sciences, Smith College, Northampton, MA 01063, United States of America
| | - Riccardo Racicot
- Department of Biological Sciences, Smith College, Northampton, MA 01063, United States of America
| | - Matthew J Fuxjager
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, United States of America
| | - Doris Preininger
- Department of Evolutionary Biology, University of Vienna, Vienna, Austria; Vienna Zoo, Vienna, Austria
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2
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Ogura Y, Sahashi K, Hirunagi T, Iida M, Miyata T, Katsuno M. Mid1 is associated with androgen-dependent axonal vulnerability of motor neurons in spinal and bulbar muscular atrophy. Cell Death Dis 2022; 13:601. [PMID: 35821212 PMCID: PMC9276699 DOI: 10.1038/s41419-022-05001-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/31/2022] [Accepted: 06/07/2022] [Indexed: 01/21/2023]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an adult-onset hereditary neurodegenerative disease caused by the expansions of CAG repeats in the androgen receptor (AR) gene. Androgen-dependent nuclear accumulation of pathogenic AR protein causes degeneration of lower motor neurons, leading to progressive muscle weakness and atrophy. While the successful induction of SBMA-like pathology has been achieved in mouse models, mechanisms underlying motor neuron vulnerability remain unclear. In the present study, we performed a transcriptome-based screening for genes expressed exclusively in motor neurons and dysregulated in the spinal cord of SBMA mice. We found upregulation of Mid1 encoding a microtubule-associated RNA binding protein which facilitates the translation of CAG-expanded mRNAs. Based on the finding that lower motor neurons begin expressing Mid1 during embryonic stages, we developed an organotypic slice culture system of the spinal cord obtained from SBMA mouse fetuses to study the pathogenic role of Mid1 in SBMA motor neurons. Impairment of axonal regeneration arose in the spinal cord culture in SBMA mice in an androgen-dependent manner, but not in mice with non-CAG-expanded AR, and was either exacerbated or ameliorated by Mid1 overexpression or knockdown, respectively. Hence, an early Mid1 expression confers vulnerability to motor neurons, at least by inducing axonogenesis defects, in SBMA.
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Affiliation(s)
- Yosuke Ogura
- grid.27476.300000 0001 0943 978XDepartment of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kentaro Sahashi
- grid.27476.300000 0001 0943 978XDepartment of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tomoki Hirunagi
- grid.27476.300000 0001 0943 978XDepartment of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Madoka Iida
- grid.27476.300000 0001 0943 978XDepartment of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takaki Miyata
- grid.27476.300000 0001 0943 978XDepartment of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masahisa Katsuno
- grid.27476.300000 0001 0943 978XDepartment of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan ,grid.27476.300000 0001 0943 978XDepartment of Clinical Research Education, Nagoya University Graduate School of Medicine, Nagoya, Japan
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3
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Molotsky E, Liu Y, Lieberman AP, Merry DE. Neuromuscular junction pathology is correlated with differential motor unit vulnerability in spinal and bulbar muscular atrophy. Acta Neuropathol Commun 2022; 10:97. [PMID: 35791011 PMCID: PMC9258097 DOI: 10.1186/s40478-022-01402-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/23/2022] [Indexed: 11/10/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an X-linked, neuromuscular neurodegenerative disease for which there is no cure. The disease is characterized by a selective decrease in fast-muscle power (e.g., tongue pressure, grip strength) accompanied by a selective loss of fast-twitch muscle fibers. However, the relationship between neuromuscular junction (NMJ) pathology and fast-twitch motor unit vulnerability has yet to be explored. In this study, we used a cross-model comparison of two mouse models of SBMA to evaluate neuromuscular junction pathology, glycolytic-to-oxidative fiber-type switching, and cytoskeletal alterations in pre- and postsynaptic termini of tibialis anterior (TA), gastrocnemius, and soleus hindlimb muscles. We observed significantly increased NMJ and myofiber pathology in fast-twitch, glycolytic motor units of the TA and gastrocnemius compared to slow-twitch, oxidative motor units of the soleus, as seen by decreased pre- and post-synaptic membrane area, decreased pre- and post-synaptic membrane colocalization, increased acetylcholine receptor compactness, a decrease in endplate area and complexity, and deficits in neurofilament heavy chain. Our data also show evidence for metabolic dysregulation and myofiber atrophy that correlate with severity of NMJ pathology. We propose a model in which the dynamic communicative relationship between the motor neuron and muscle, along with the developmental subtype of the muscle, promotes motor unit subtype specific vulnerability, metabolic alterations, and NMJ pathology.
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Affiliation(s)
- Elana Molotsky
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Jefferson Alumni Hall, Rm. 411E, Philadelphia, PA, 19107, USA
| | - Yuhong Liu
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Jefferson Alumni Hall, Rm. 411E, Philadelphia, PA, 19107, USA
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Diane E Merry
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Jefferson Alumni Hall, Rm. 411E, Philadelphia, PA, 19107, USA.
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4
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Genetic architecture of motor neuron diseases. J Neurol Sci 2021; 434:120099. [PMID: 34965490 DOI: 10.1016/j.jns.2021.120099] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/26/2021] [Accepted: 12/14/2021] [Indexed: 12/18/2022]
Abstract
Motor neuron diseases (MNDs) are rare and frequently fatal neurological disorders in which motor neurons within the brainstem and spinal cord regions slowly die. MNDs are primarily caused by genetic mutations, and > 100 different mutant genes in humans have been discovered thus far. Given the fact that many more MND-related genes have yet to be discovered, the growing body of genetic evidence has offered new insights into the diverse cellular and molecular mechanisms involved in the aetiology and pathogenesis of MNDs. This search may aid in the selection of potential candidate genes for future investigation and, eventually, may open the door to novel interventions to slow down disease progression. In this review paper, we have summarized detailed existing research findings of different MNDs, such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), spinal bulbar muscle atrophy (SBMA) and hereditary spastic paraplegia (HSP) in relation to their complex genetic architecture.
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5
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Silva AC, Lobo DD, Martins IM, Lopes SM, Henriques C, Duarte SP, Dodart JC, Nobre RJ, Pereira de Almeida L. Antisense oligonucleotide therapeutics in neurodegenerative diseases: the case of polyglutamine disorders. Brain 2020; 143:407-429. [PMID: 31738395 DOI: 10.1093/brain/awz328] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 08/09/2019] [Accepted: 08/22/2019] [Indexed: 12/20/2022] Open
Abstract
Polyglutamine (polyQ) disorders are a group of nine neurodegenerative diseases that share a common genetic cause, which is an expansion of CAG repeats in the coding region of the causative genes that are otherwise unrelated. The trinucleotide expansion encodes for an expanded polyQ tract in the respective proteins, resulting in toxic gain-of-function and eventually in neurodegeneration. Currently, no disease-modifying therapies are available for this group of disorders. Nevertheless, given their monogenic nature, polyQ disorders are ideal candidates for therapies that target specifically the gene transcripts. Antisense oligonucleotides (ASOs) have been under intense investigation over recent years as gene silencing tools. ASOs are small synthetic single-stranded chains of nucleic acids that target specific RNA transcripts through several mechanisms. ASOs can reduce the levels of mutant proteins by breaking down the targeted transcript, inhibit mRNA translation or alter the maturation of the pre-mRNA via splicing correction. Over the years, chemical optimization of ASO molecules has allowed significant improvement of their pharmacological properties, which has in turn made this class of therapeutics a very promising strategy to treat a variety of neurodegenerative diseases. Indeed, preclinical and clinical strategies have been developed in recent years for some polyQ disorders using ASO therapeutics. The success of ASOs in several animal models, as well as encouraging results in the clinic for Huntington's disease, points towards a promising future regarding the application of ASO-based therapies for polyQ disorders in humans, offering new opportunities to address unmet medical needs for this class of disorders. This review aims to present a brief overview of key chemical modifications, mechanisms of action and routes of administration that have been described for ASO-based therapies. Moreover, it presents a review of the most recent and relevant preclinical and clinical trials that have tested ASO therapeutics in polyQ disorders.
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Affiliation(s)
- Ana C Silva
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Diana D Lobo
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Inês M Martins
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Sara M Lopes
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Carina Henriques
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,ViraVector, Viral Vector for Gene Transfer Core Facility, University of Coimbra, Coimbra, Portugal
| | - Sónia P Duarte
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | | | - Rui Jorge Nobre
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal.,ViraVector, Viral Vector for Gene Transfer Core Facility, University of Coimbra, Coimbra, Portugal
| | - Luis Pereira de Almeida
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,ViraVector, Viral Vector for Gene Transfer Core Facility, University of Coimbra, Coimbra, Portugal.,Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
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6
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Halievski K, Xu Y, Haddad YW, Tang YP, Yamada S, Katsuno M, Adachi H, Sobue G, Breedlove SM, Jordan CL. Muscle BDNF improves synaptic and contractile muscle strength in Kennedy's disease mice in a muscle-type specific manner. J Physiol 2020; 598:2719-2739. [PMID: 32306402 DOI: 10.1113/jp279208] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 04/14/2020] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Muscle-derived neurotrophic factors may offer therapeutic promise for treating neuromuscular diseases. We report that a muscle-derived neurotrophic factor, BDNF, rescues synaptic and muscle function in a muscle-type specific manner in mice modelling Kennedy's disease (KD). We also find that BDNF rescues select molecular mechanisms in slow and fast muscle that may underlie the improved cellular function. We also report for the first time that expression of BDNF, but not other members of the neurotrophin family, is perturbed in muscle from patients with KD. Given that muscle BDNF had divergent therapeutic effects that depended on muscle type, a combination of neurotrophic factors may optimally rescue neuromuscular function via effects on both pre- and postsynaptic function, in the face of disease. ABSTRACT Deficits in muscle brain-derived neurotrophic factor (BDNF) correlate with neuromuscular deficits in mouse models of Kennedy's disease (KD), suggesting that restoring muscle BDNF might restore function. To test this possibility, transgenic mice expressing human BDNF in skeletal muscle were crossed with '97Q' KD mice. We found that muscle BDNF slowed disease, doubling the time between symptom onset and endstage. BDNF also improved expression of genes in muscle known to play key roles in neuromuscular function, including counteracting the expression of neonatal isoforms induced by disease. Intriguingly, BDNF's ameliorative effects differed between muscle types: synaptic strength was rescued only in slow-twitch muscle, while contractile strength was improved only in fast-twitch muscle. In sum, muscle BDNF slows disease progression, rescuing select cellular and molecular mechanisms that depend on fibre type. Muscle BDNF expression was also affected in KD patients, reinforcing its translational and therapeutic potential for treating this disorder.
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Affiliation(s)
- Katherine Halievski
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA.,Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada
| | - Youfen Xu
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA
| | - Yazeed W Haddad
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA
| | - Yu Ping Tang
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA
| | - Shinichiro Yamada
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environment Health School of Medicine, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka, 807-8555, Japan
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - S Marc Breedlove
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA
| | - Cynthia L Jordan
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA.,Physiology Department, Michigan State University, 108 Giltner Hall, East Lansing, MI, 48824-1115, USA
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7
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Halievski K, Nath SR, Katsuno M, Adachi H, Sobue G, Breedlove SM, Lieberman AP, Jordan CL. Disease Affects Bdnf Expression in Synaptic and Extrasynaptic Regions of Skeletal Muscle of Three SBMA Mouse Models. Int J Mol Sci 2019; 20:ijms20061314. [PMID: 30875922 PMCID: PMC6470984 DOI: 10.3390/ijms20061314] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/08/2019] [Accepted: 03/09/2019] [Indexed: 01/01/2023] Open
Abstract
Spinal bulbar muscular atrophy (SBMA) is a slowly progressive, androgen-dependent neuromuscular disease in men that is characterized by both muscle and synaptic dysfunction. Because gene expression in muscle is heterogeneous, with synaptic myonuclei expressing genes that regulate synaptic function and extrasynaptic myonuclei expressing genes to regulate contractile function, we used quantitative PCR to compare gene expression in these two domains of muscle from three different mouse models of SBMA: the "97Q" model that ubiquitously expresses mutant human androgen receptor (AR), the 113Q knock-in (KI) model that expresses humanized mouse AR with an expanded glutamine tract, and the "myogenic" model that overexpresses wild-type rat AR only in skeletal muscle. We were particularly interested in neurotrophic factors because of their role in maintaining neuromuscular function via effects on both muscle and synaptic function, and their implicated role in SBMA. We confirmed previous reports of the enriched expression of select genes (e.g., the acetylcholine receptor) in the synaptic region of muscle, and are the first to report the synaptic enrichment of others (e.g., glial cell line-derived neurotrophic factor). Interestingly, all three models displayed comparably dysregulated expression of most genes examined in both the synaptic and extrasynaptic domains of muscle, with only modest differences between regions and models. These findings of comprehensive gene dysregulation in muscle support the emerging view that skeletal muscle may be a prime therapeutic target for restoring function of both muscles and motoneurons in SBMA.
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Affiliation(s)
- Katherine Halievski
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
| | - Samir R Nath
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environment Health School of Medicine, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu Fukuoka 807-8555, Japan.
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - S Marc Breedlove
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Cynthia L Jordan
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
- Physiology Department, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
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8
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Xu Y, Halievski K, Katsuno M, Adachi H, Sobue G, Breedlove SM, Jordan CL. Pre-clinical symptoms of SBMA may not be androgen-dependent: implications from two SBMA mouse models. Hum Mol Genet 2019; 27:2425-2442. [PMID: 29897452 DOI: 10.1093/hmg/ddy142] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/16/2018] [Indexed: 12/31/2022] Open
Abstract
A distinguishing aspect of spinal and bulbar muscular atrophy (SBMA) is its androgen-dependence, possibly explaining why only males are clinically affected. This disease, which impairs neuromuscular function, is linked to a polyglutamine expansion mutation in the androgen receptor (AR). In mouse models of SBMA, motor dysfunction is associated with pronounced defects in neuromuscular transmission, including defects in evoked transmitter release (quantal content, QC) and fiber membrane excitability (based on the resting membrane potential, RMP). However, whether such defects are androgen-dependent is unknown. Thus, we recorded synaptic potentials intracellularly from adult muscle fibers of transgenic (Tg) AR97Q male mice castrated pre-symptomatically. Although castration largely protects both QC and the RMP of fibers, correlating with the protective effect of castration on motor function, significant deficits in QC and RMP remained. Surprisingly, comparable defects in QC and RMP were also observed in pre-symptomatic AR97Q males, indicating that such defects emerge early and are pre-clinical. Exposing asymptomatic Tg females to androgens also induces both motor dysfunction and comparable defects in QC and RMP. Notably, asymptomatic Tg females also showed significant deficits in QC and RMP, albeit less severe, supporting their pre-clinical nature, but also raising questions about the androgen-dependence of pre-clinical symptoms. In summary, current evidence indicates that disease progression depends on androgens, but early pathogenic events may be triggered by the mutant AR allele independent of androgens. Such early, androgen-independent disease mechanisms may also be relevant to females carrying the SBMA allele.
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Affiliation(s)
- Youfen Xu
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
| | | | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Japan
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environment Health School of Medicine, Yahatanishi-ku, Kitakyushu Fukuoka, Japan
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Japan
| | - S Marc Breedlove
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
| | - Cynthia L Jordan
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
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9
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Lieberman AP, Shakkottai VG, Albin RL. Polyglutamine Repeats in Neurodegenerative Diseases. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2018; 14:1-27. [PMID: 30089230 DOI: 10.1146/annurev-pathmechdis-012418-012857] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Among the age-dependent protein aggregation disorders, nine neurodegenerative diseases are caused by expansions of CAG repeats encoding polyglutamine (polyQ) tracts. We review the clinical, pathological, and biological features of these inherited disorders. We discuss insights into pathogenesis gleaned from studies of model systems and patients, highlighting work that informs efforts to develop effective therapies. An important conclusion from these analyses is that expanded CAG/polyQ domains are the primary drivers of neurodegeneration, with the biology of carrier proteins influencing disease-specific manifestations. Additionally, it has become apparent that CAG/polyQ repeat expansions produce neurodegeneration via multiple downstream mechanisms, involving both gain- and loss-of-function effects. This conclusion indicates that the likelihood of developing effective therapies targeting single nodes is reduced. The evaluation of treatments for premanifest disease will likely require new investigational approaches. We highlight the opportunities and challenges underlying ongoing work and provide recommendations related to the development of symptomatic and disease-modifying therapies and biomarkers that could inform future research.
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Affiliation(s)
- Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA;
| | - Vikram G Shakkottai
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA; , .,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Roger L Albin
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA; , .,Neurology Service and the Geriatric Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare System, Ann Arbor, Michigan 48105, USA
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10
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Nath SR, Yu Z, Gipson TA, Marsh GB, Yoshidome E, Robins DM, Todi SV, Housman DE, Lieberman AP. Androgen receptor polyglutamine expansion drives age-dependent quality control defects and muscle dysfunction. J Clin Invest 2018; 128:3630-3641. [PMID: 29809168 DOI: 10.1172/jci99042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 05/24/2018] [Indexed: 12/28/2022] Open
Abstract
Skeletal muscle has emerged as a critical, disease-relevant target tissue in spinal and bulbar muscular atrophy, a degenerative disorder of the neuromuscular system caused by a CAG/polyglutamine (polyQ) expansion in the androgen receptor (AR) gene. Here, we used RNA-sequencing (RNA-Seq) to identify pathways that are disrupted in diseased muscle using AR113Q knockin mice. This analysis unexpectedly identified substantially diminished expression of numerous ubiquitin/proteasome pathway genes in AR113Q muscle, encoding approximately 30% of proteasome subunits and 20% of E2 ubiquitin conjugases. These changes were age, hormone, and glutamine length dependent and arose due to a toxic gain of function conferred by the mutation. Moreover, altered gene expression was associated with decreased levels of the proteasome transcription factor NRF1 and its activator DDI2 and resulted in diminished proteasome activity. Ubiquitinated ADRM1 was detected in AR113Q muscle, indicating the occurrence of stalled proteasomes in mutant mice. Finally, diminished expression of Drosophila orthologues of NRF1 or ADRM1 promoted the accumulation of polyQ AR protein and increased toxicity. Collectively, these data indicate that AR113Q muscle develops progressive proteasome dysfunction that leads to the impairment of quality control and the accumulation of polyQ AR protein, key features that contribute to the age-dependent onset and progression of this disorder.
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Affiliation(s)
- Samir R Nath
- Department of Pathology.,Medical Scientist Training Program, and.,Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Theresa A Gipson
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Gregory B Marsh
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | | | - Diane M Robins
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - David E Housman
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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11
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Pennuto M, Rinaldi C. From gene to therapy in spinal and bulbar muscular atrophy: Are we there yet? Mol Cell Endocrinol 2018; 465:113-121. [PMID: 28688959 DOI: 10.1016/j.mce.2017.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/30/2017] [Accepted: 07/03/2017] [Indexed: 01/12/2023]
Abstract
Abnormal polyglutamine expansions in the androgen receptor (AR) cause a muscular condition, known as Kennedy's disease or spinal and bulbar muscular atrophy (SBMA). The disease is transmitted in an X-linked fashion and is clinically characterized by weakness, atrophy and fasciculations of the limb and bulbar muscles as a result of a toxic gain-of-function of the mutant protein. Notably, affected males also show signs of androgen insensitivity, such as gynaecomastia and reduced fertility. The characterization of the natural history of the disease, the increasing understanding of the mechanism of pathogenesis and the elucidation of the functions of normal and mutant AR have offered a momentum for developing a rational therapeutic strategy for this disease. In this special issue on androgens and AR functions, we will review the molecular, biochemical, and cellular mechanisms underlying the pathogenesis of SBMA. We will discuss recent advances on therapeutic approaches and opportunities for this yet incurable disease, ranging from androgen deprivation, to gene silencing, to an expanding repertoire of peripheral targets, including muscle. With the advancement of these strategies into the clinic, it can be reasonably anticipated that the landscape of treatment options for SBMA and other neuromuscular conditions will change rapidly in the near future.
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Affiliation(s)
- Maria Pennuto
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, 38123 Trento, Italy; Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy.
| | - Carlo Rinaldi
- Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3QX Oxford, UK.
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12
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Abstract
Spinal and bulbar muscular atrophy (SBMA) is an adult-onset degenerative disorder of the neuromuscular system resulting in slowly progressive weakness and atrophy of the proximal limb and bulbar muscles. The disease is caused by the expansion of a CAG/glutamine tract in the amino-terminus of the androgen receptor. That SBMA exclusively affects males reflects the fact that critical pathogenic events are hormone-dependent. These include translocation of the polyglutamine androgen receptor from the cytoplasm to the nucleus and unfolding of the mutant protein. Studies of the pathology of SBMA subjects have revealed nuclear aggregates of the mutant androgen receptor, loss of lower motor neurons in the brainstem and spinal cord, and both neurogenic and myopathic changes in skeletal muscle. Mechanisms underlying disease pathogenesis include toxicity in both lower motor neurons and skeletal muscle, where effects on transcription, intracellular transport, and mitochondrial function have been documented. Therapies to treat SBMA patients remain largely supportive, although experimental approaches targeting androgen action or promoting degradation of the mutant androgen receptor protein or the encoding RNA are under active study.
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13
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X-Linked Spinal and Bulbar Muscular Atrophy: From Clinical Genetic Features and Molecular Pathology to Mechanisms Underlying Disease Toxicity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:103-133. [PMID: 29427100 DOI: 10.1007/978-3-319-71779-1_5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spinal and Bulbar Muscular Atrophy (SBMA) is an inherited neuromuscular disorder caused by a CAG-polyglutamine (polyQ) repeat expansion in the androgen receptor (AR) gene. Unlike other polyQ diseases, where the function of the native causative protein is unknown, the biology of AR is well understood, and this knowledge has informed our understanding of how native AR function interfaces with polyQ-AR dysfunction. Furthermore, ligand-dependent activation of AR has been linked to SBMA disease pathogenesis, and has led to a thorough study of androgen-mediated effects on polyQ-AR stability, degradation, and post-translational modifications, as well as their roles in the disease process. Transcriptional dysregulation, proteostasis dysfunction, and mitochondrial abnormalities are central to polyQ-AR neurotoxicity, most likely via a 'change-of-function' mechanism. Intriguingly, recent work has demonstrated a principal role for skeletal muscle in SBMA disease pathogenesis, indicating that polyQ-AR toxicity initiates in skeletal muscle and results in secondary motor neuron demise. The existence of robust animal models for SBMA has permitted a variety of preclinical trials, driven by recent discoveries of altered cellular processes, and some of this preclinical work has led to human clinical trials. In this chapter, we review SBMA clinical features and disease biology, discuss our current understanding of the cellular and molecular basis of SBMA pathogenesis, and highlight ongoing efforts toward therapy development.
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14
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Giorgetti E, Yu Z, Chua JP, Shimamura R, Zhao L, Zhu F, Venneti S, Pennuto M, Guan Y, Hung G, Lieberman AP. Rescue of Metabolic Alterations in AR113Q Skeletal Muscle by Peripheral Androgen Receptor Gene Silencing. Cell Rep 2017; 17:125-136. [PMID: 27681426 DOI: 10.1016/j.celrep.2016.08.084] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 07/05/2016] [Accepted: 08/24/2016] [Indexed: 01/09/2023] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA), a progressive degenerative disorder, is caused by a CAG/glutamine expansion in the androgen receptor (polyQ AR). Recent studies demonstrate that skeletal muscle is an important site of toxicity that contributes to the SBMA phenotype. Here, we sought to identify critical pathways altered in muscle that underlie disease manifestations in AR113Q mice. This led to the unanticipated identification of gene expression changes affecting regulators of carbohydrate metabolism, similar to those triggered by denervation. AR113Q muscle exhibits diminished glycolysis, altered mitochondria, and an impaired response to exercise. Strikingly, the expression of genes regulating muscle energy metabolism is rescued following peripheral polyQ AR gene silencing by antisense oligonucleotides (ASO), a therapeutic strategy that alleviates disease. Our data establish the occurrence of a metabolic imbalance in SBMA muscle triggered by peripheral expression of the polyQ AR and indicate that alterations in energy utilization contribute to non-neuronal disease manifestations.
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Affiliation(s)
- Elisa Giorgetti
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Zhigang Yu
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Jason P Chua
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ryosuke Shimamura
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lili Zhao
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, MI 48109, USA
| | - Fan Zhu
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Sriram Venneti
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Maria Pennuto
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, Trento 38123, Italy
| | - Yuanfang Guan
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Gene Hung
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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15
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Francis SP, Cunningham LL. Non-autonomous Cellular Responses to Ototoxic Drug-Induced Stress and Death. Front Cell Neurosci 2017; 11:252. [PMID: 28878625 PMCID: PMC5572385 DOI: 10.3389/fncel.2017.00252] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/08/2017] [Indexed: 12/20/2022] Open
Abstract
The first major recognition of drug-induced hearing loss can be traced back more than seven decades to the development of streptomycin as an antimicrobial agent. Since then at least 130 therapeutic drugs have been recognized as having ototoxic side-effects. Two important classes of ototoxic drugs are the aminoglycoside antibiotics and the platinum-based antineoplastic agents. These drugs save the lives of millions of people worldwide, but they also cause irreparable hearing loss. In the inner ear, sensory hair cells (HCs) and spiral ganglion neurons (SGNs) are important cellular targets of these drugs, and most mechanistic studies have focused on the cell-autonomous responses of these cell types in response to ototoxic stress. Despite several decades of studies on ototoxicity, important unanswered questions remain, including the cellular and molecular mechanisms that determine whether HCs and SGNs will live or die when confronted with ototoxic challenge. Emerging evidence indicates that other cell types in the inner ear can act as mediators of survival or death of sensory cells and SGNs. For example, glia-like supporting cells (SCs) can promote survival of both HCs and SGNs. Alternatively, SCs can act to promote HC death and inhibit neural fiber expansion. Similarly, tissue resident macrophages activate either pro-survival or pro-death signaling that can influence HC survival after exposure to ototoxic agents. Together these data indicate that autonomous responses that occur within a stressed HC or SGN are not the only (and possibly not the primary) determinants of whether the stressed cell ultimately lives or dies. Instead non-cell-autonomous responses are emerging as significant determinants of HC and SGN survival vs. death in the face of ototoxic stress. The goal of this review is to summarize the current evidence on non-cell-autonomous responses to ototoxic stress and to discuss ways in which this knowledge may advance the development of therapies to reduce hearing loss caused by these drugs.
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Affiliation(s)
- Shimon P Francis
- National Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesda, MD, United States
| | - Lisa L Cunningham
- National Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesda, MD, United States
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16
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Defects in Neuromuscular Transmission May Underlie Motor Dysfunction in Spinal and Bulbar Muscular Atrophy. J Neurosci 2017; 36:5094-106. [PMID: 27147661 DOI: 10.1523/jneurosci.3485-15.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 03/22/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Spinal and bulbar muscular atrophy (SBMA) in men is an androgen-dependent neuromuscular disease caused by expanded CAG repeats in the androgen receptor (AR). Whether muscle or motor neuron dysfunction or both underlies motor impairment in SBMA is unknown. Muscles of SBMA mice show significant contractile dysfunction, implicating them as a likely source of motor dysfunction, but whether disease also impairs neuromuscular transmission is an open question. Thus, we examined synaptic function in three well-studied SBMA mouse models-the AR97Q, knock-in (KI), and myogenic141 models-by recording in vitro miniature and evoked end-plate potentials (MEPPs and EPPs, respectively) intracellularly from adult muscle fibers. We found striking defects in neuromuscular transmission suggesting that toxic AR in SBMA impairs both presynaptic and postsynaptic mechanisms. Notably, SBMA causes neuromuscular synapses to become weak and muscles to become hyperexcitable in all three models. Presynaptic defects included deficits in quantal content, reduced size of the readily releasable pool, and impaired short-term facilitation. Postsynaptic defects included prolonged decay times for both MEPPs and EPPs, marked resistance to μ-conotoxin (a sodium channel blocker), and enhanced membrane excitability. Quantitative PCR revealed robust upregulation of mRNAs encoding neonatal isoforms of the AChR (γ-subunit) and the voltage-gated sodium channel (NaV1.5) in diseased adult muscles of all three models, consistent with the observed slowing of synaptic potentials and resistance to μ-conotoxin. These findings suggest that muscles of SBMA patients regress to an immature state that impairs neuromuscular function. SIGNIFICANCE STATEMENT We have discovered that SBMA is accompanied by marked defects in neuromuscular synaptic transmission involving both presynaptic and postsynaptic mechanisms. For three different mouse models, we find that diseased synapses are weak, having reduced quantal content due to reductions in the size of the readily releasable pool and/or probability of release. Synaptic potentials in diseased adult fibers are slowed, explained by an aberrant upregulation of the neonatal isoform of the acetylcholine receptor. Diseased fibers also show marked resistance to μ-conotoxin, explained by an aberrant upregulation in the neonatal isoform of the sodium channel, and are hyperexcitable, reminiscent of myotonic dystrophy, showing anode-break action potentials. This work identifies several new molecular targets for recovering function in SBMA.
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17
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Nath SR, Lieberman AP. The Ubiquitination, Disaggregation and Proteasomal Degradation Machineries in Polyglutamine Disease. Front Mol Neurosci 2017; 10:78. [PMID: 28381987 PMCID: PMC5360718 DOI: 10.3389/fnmol.2017.00078] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 03/06/2017] [Indexed: 12/14/2022] Open
Abstract
Polyglutamine disorders are chronic, progressive neurodegenerative diseases caused by expansion of a glutamine tract in widely expressed genes. Despite excellent models of disease, a well-documented clinical history and progression, and established genetic causes, there are no FDA approved, disease modifying treatments for these disorders. Downstream of the mutant protein, several divergent pathways of toxicity have been identified over the last several decades, supporting the idea that targeting only one of these pathways of toxicity is unlikely to robustly alleviate disease progression. As a result, a vast body of research has focused on eliminating the mutant protein to broadly prevent downstream toxicity, either by silencing mutant protein expression or leveraging the endogenous protein quality control machinery. In the latter approach, a focus has been placed on four critical components of mutant protein degradation that are active in the nucleus, a key site of toxicity: disaggregation, ubiquitination, deubiquitination, and proteasomal activity. These machineries have unique functional components, but work together as a cellular defense system that can be successfully leveraged to alleviate disease phenotypes in several models of polyglutamine toxicity. This review will highlight recent advances in understanding both the potential and role of these components of the protein quality control machinery in polyglutamine disease pathophysiology.
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Affiliation(s)
- Samir R Nath
- Medical Scientist Training Program, University of Michigan Medical SchoolAnn Arbor, MI, USA; Cellular and Molecular Biology Graduate Program, University of Michigan Medical SchoolAnn Arbor, MI, USA; Department of Pathology, University of Michigan Medical SchoolAnn Arbor, MI, USA
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School Ann Arbor, MI, USA
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18
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Milioto C, Malena A, Maino E, Polanco MJ, Marchioretti C, Borgia D, Pereira MG, Blaauw B, Lieberman AP, Venturini R, Plebani M, Sambataro F, Vergani L, Pegoraro E, Sorarù G, Pennuto M. Beta-agonist stimulation ameliorates the phenotype of spinal and bulbar muscular atrophy mice and patient-derived myotubes. Sci Rep 2017; 7:41046. [PMID: 28117338 PMCID: PMC5259768 DOI: 10.1038/srep41046] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/15/2016] [Indexed: 02/02/2023] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease characterized by the loss of lower motor neurons. SBMA is caused by expansions of a polyglutamine tract in the gene coding for androgen receptor (AR). Expression of polyglutamine-expanded AR causes damage to motor neurons and skeletal muscle cells. Here we investigated the effect of β-agonist stimulation in SBMA myotube cells derived from mice and patients, and in knock-in mice. We show that treatment of myotubes expressing polyglutamine-expanded AR with the β-agonist clenbuterol increases their size. Clenbuterol activated the phosphatidylinositol-3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway and decreased the accumulation of polyglutamine-expanded AR. Treatment of SBMA knock-in mice with clenbuterol, which was started at disease onset, ameliorated motor function and extended survival. Clenbuterol improved muscle pathology, attenuated the glycolytic-to-oxidative metabolic alterations occurring in SBMA muscles and induced hypertrophy of both glycolytic and oxidative fibers. These results indicate that β-agonist stimulation is a novel therapeutic strategy for SBMA.
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Affiliation(s)
- Carmelo Milioto
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, 38123 Trento, Italy.,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, 16163 Genova, Italy.,Dipartimento di Medicina Sperimentale, University of Genova, 16100 Genova, Italy
| | - Adriana Malena
- Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - Eleonora Maino
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Maria J Polanco
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Caterina Marchioretti
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Doriana Borgia
- Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - Marcelo Gomes Pereira
- Venetian Institute of Molecular Medicine, Department of Biomedical Science, University of Padova, 35100 Padova, Italy
| | - Bert Blaauw
- Venetian Institute of Molecular Medicine, Department of Biomedical Science, University of Padova, 35100 Padova, Italy
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Roberta Venturini
- Department of Laboratory Medicine, University Hospital of Padova, 35100 Padova, Italy
| | - Mario Plebani
- Department of Laboratory Medicine, University Hospital of Padova, 35100 Padova, Italy
| | - Fabio Sambataro
- Department of Experimental &Clinical Medical Sciences (DISM), University of Udine, 33100 Udine, Italy
| | - Lodovica Vergani
- Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - Elena Pegoraro
- Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - Gianni Sorarù
- Department of Neurosciences, University of Padova, 35100 Padova, Italy
| | - Maria Pennuto
- Dulbecco Telethon Institute, Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
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19
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Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model. eNeuro 2016; 3:eN-NWR-0062-16. [PMID: 27517091 PMCID: PMC4978821 DOI: 10.1523/eneuro.0062-16.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 06/23/2016] [Accepted: 07/14/2016] [Indexed: 11/25/2022] Open
Abstract
Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique “myogenic” transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons.
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20
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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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21
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Glycolytic-to-oxidative fiber-type switch and mTOR signaling activation are early-onset features of SBMA muscle modified by high-fat diet. Acta Neuropathol 2016; 132:127-44. [PMID: 26971100 PMCID: PMC4911374 DOI: 10.1007/s00401-016-1550-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/19/2016] [Accepted: 02/19/2016] [Indexed: 12/13/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by the expansion of a polyglutamine tract in the androgen receptor (AR). The mechanism by which expansion of polyglutamine in AR causes muscle atrophy is unknown. Here, we investigated pathological pathways underlying muscle atrophy in SBMA knock-in mice and patients. We show that glycolytic muscles were more severely affected than oxidative muscles in SBMA knock-in mice. Muscle atrophy was associated with early-onset, progressive glycolytic-to-oxidative fiber-type switch. Whole genome microarray and untargeted lipidomic analyses revealed enhanced lipid metabolism and impaired glycolysis selectively in muscle. These metabolic changes occurred before denervation and were associated with a concurrent enhancement of mechanistic target of rapamycin (mTOR) signaling, which induced peroxisome proliferator-activated receptor γ coactivator 1 alpha (PGC1α) expression. At later stages of disease, we detected mitochondrial membrane depolarization, enhanced transcription factor EB (TFEB) expression and autophagy, and mTOR-induced protein synthesis. Several of these abnormalities were detected in the muscle of SBMA patients. Feeding knock-in mice a high-fat diet (HFD) restored mTOR activation, decreased the expression of PGC1α, TFEB, and genes involved in oxidative metabolism, reduced mitochondrial abnormalities, ameliorated muscle pathology, and extended survival. These findings show early-onset and intrinsic metabolic alterations in SBMA muscle and link lipid/glucose metabolism to pathogenesis. Moreover, our results highlight an HFD regime as a promising approach to support SBMA patients.
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22
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Bott LC, Salomons FA, Maric D, Liu Y, Merry D, Fischbeck KH, Dantuma NP. The polyglutamine-expanded androgen receptor responsible for spinal and bulbar muscular atrophy inhibits the APC/C(Cdh1) ubiquitin ligase complex. Sci Rep 2016; 6:27703. [PMID: 27312068 PMCID: PMC4911547 DOI: 10.1038/srep27703] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/24/2016] [Indexed: 01/05/2023] Open
Abstract
Polyglutamine expansion in the androgen receptor (AR) causes spinal and bulbar muscular atrophy (SBMA), an X-linked neuromuscular disease that is fully manifest only in males. It has been suggested that proteins with expanded polyglutamine tracts impair ubiquitin-dependent proteolysis due to their propensity to aggregate, but recent studies indicate that the overall activity of the ubiquitin-proteasome system is preserved in SBMA models. Here we report that AR selectively interferes with the function of the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C), which, together with its substrate adaptor Cdh1, is critical for cell cycle arrest and neuronal architecture. We show that both wild-type and mutant AR physically interact with the APC/CCdh1 complex in a ligand-dependent fashion without being targeted for proteasomal degradation. Inhibition of APC/CCdh1 by mutant but not wild-type AR in PC12 cells results in enhanced neurite outgrowth which is typically followed by rapid neurite retraction and mitotic entry. Our data indicate a role of AR in neuronal differentiation through regulation of APC/CCdh1 and suggest abnormal cell cycle reactivation as a pathogenic mechanism in SBMA.
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Affiliation(s)
- Laura C Bott
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm 17177, Sweden.,National Institute of Neurological Disorders and Stroke, Neurogenetics Branch, Bethesda, MD 20892, USA
| | - Florian A Salomons
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm 17177, Sweden
| | - Dragan Maric
- Flow Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Yuhong Liu
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Diane Merry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kenneth H Fischbeck
- National Institute of Neurological Disorders and Stroke, Neurogenetics Branch, Bethesda, MD 20892, USA
| | - Nico P Dantuma
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm 17177, Sweden
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23
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Sahashi K, Katsuno M, Hung G, Adachi H, Kondo N, Nakatsuji H, Tohnai G, Iida M, Bennett CF, Sobue G. Silencing neuronal mutant androgen receptor in a mouse model of spinal and bulbar muscular atrophy. Hum Mol Genet 2015; 24:5985-94. [PMID: 26231218 DOI: 10.1093/hmg/ddv300] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/21/2015] [Indexed: 12/25/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA), an adult-onset neurodegenerative disease that affects males, results from a CAG triplet repeat/polyglutamine expansions in the androgen receptor (AR) gene. Patients develop progressive muscular weakness and atrophy, and no effective therapy is currently available. The tissue-specific pathogenesis, especially relative pathological contributions between degenerative motor neurons and muscles, remains inconclusive. Though peripheral pathology in skeletal muscle caused by toxic AR protein has been recently reported to play a pivotal role in the pathogenesis of SBMA using mouse models, the role of motor neuron degeneration in SBMA has not been rigorously investigated. Here, we exploited synthetic antisense oligonucleotides to inhibit the RNA levels of mutant AR in the central nervous system (CNS) and explore its therapeutic effects in our SBMA mouse model that harbors a mutant AR gene with 97 CAG expansions and characteristic SBMA-like neurogenic phenotypes. A single intracerebroventricular administration of the antisense oligonucleotides in the presymptomatic phase efficiently suppressed the mutant gene expression in the CNS, and delayed the onset and progression of motor dysfunction, improved body weight gain and survival with the amelioration of neuronal histopathology in motor units such as spinal motor neurons, neuromuscular junctions and skeletal muscle. These findings highlight the importance of the neurotoxicity of mutant AR protein in motor neurons as a therapeutic target.
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Affiliation(s)
- Kentaro Sahashi
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan,
| | - Gene Hung
- Isis Pharmaceuticals, Carlsbad, CA 92008, USA and
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, Kitakyushu 807-8555, Japan
| | - Naohide Kondo
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hideaki Nakatsuji
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Genki Tohnai
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Madoka Iida
- 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,
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24
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Halievski K, Henley CL, Domino L, Poort JE, Fu M, Katsuno M, Adachi H, Sobue G, Breedlove SM, Jordan CL. Androgen-dependent loss of muscle BDNF mRNA in two mouse models of SBMA. Exp Neurol 2015; 269:224-32. [PMID: 25929689 DOI: 10.1016/j.expneurol.2015.04.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/03/2015] [Accepted: 04/21/2015] [Indexed: 10/23/2022]
Abstract
Transgenic expression of neurotrophic factors in skeletal muscle has been found to protect mice from neuromuscular disease, including spinal bulbar muscular atrophy (SBMA), triggering renewed interest in neurotrophic factors as therapeutic agents for treating neuromuscular disease. Because SBMA is an androgen-dependent disease, and brain-derived neurotrophic factor (BDNF) mediates effects of androgens on neuromuscular systems, we asked whether BDNF expression is impaired in two different transgenic (Tg) mouse models of SBMA, the so called "97Q" and "myogenic" SBMA models. The 97Q model globally overexpresses a full length human AR with 97 glutamine repeats whereas the myogenic model of SBMA overexpresses a wild-type rat androgen receptor (AR) only in skeletal muscle fibers. Using quantitative PCR, we find that muscle BDNF mRNA declines in an androgen-dependent manner in both models, paralleling changes in motor function, with robust deficits (6-8 fold) in both fast and slow twitch muscles of impaired Tg males. Castration rescues or reverses disease-related deficits in muscle BDNF mRNA in both models, paralleling its effect on motor function. Moreover, when disease is acutely induced in Tg females, both motor function and muscle BDNF mRNA expression plummet, with the deficit in muscle BDNF emerging before overt motor dysfunction. That androgen-dependent motor dysfunction is tightly associated with a robust and early down-regulation of muscle BDNF mRNA suggests that BDNF delivered to skeletal muscle may have therapeutic value for SBMA.
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Affiliation(s)
- Katherine Halievski
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA.
| | - Casey L Henley
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA
| | - Laurel Domino
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA
| | - Jessica E Poort
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA
| | - Martina Fu
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka 807-8555, Japan
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - S Marc Breedlove
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA
| | - Cynthia L Jordan
- Neuroscience Program, Michigan State University, 293 Farm Lane, 108 Giltner, East Lansing, MI 48824-1101, USA
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Halievski K, Mo K, Westwood JT, Monks DA. Transcriptional profile of muscle following acute induction of symptoms in a mouse model of Kennedy's disease/spinobulbar muscular atrophy. PLoS One 2015; 10:e0118120. [PMID: 25719894 PMCID: PMC4341878 DOI: 10.1371/journal.pone.0118120] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 01/07/2015] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Kennedy's disease/Spinobulbar muscular atrophy (KD/SBMA) is a degenerative neuromuscular disease affecting males. This disease is caused by polyglutamine expansion mutations of the androgen receptor (AR) gene. Although KD/SBMA has been traditionally considered a motor neuron disease, emerging evidence points to a central etiological role of muscle. We previously reported a microarray study of genes differentially expressed in muscle of three genetically unique mouse models of KD/SBMA but were unable to detect those which are androgen-dependent or are associated with onset of symptoms. METHODOLOGY/PRINCIPAL FINDINGS In the current study we examined the time course and androgen-dependence of transcriptional changes in the HSA-AR transgenic (Tg) mouse model, in which females have a severe phenotype after acute testosterone treatment. Using microarray analysis we identified differentially expressed genes at the onset and peak of muscle weakness in testosterone-treated Tg females. We found both transient and persistent groups of differentially expressed genes and analysis of gene function indicated functional groups such as mitochondrion, ion and nucleotide binding, muscle development, and sarcomere maintenance. CONCLUSIONS/SIGNIFICANCE By comparing the current results with those from the three previously reported models we were able to identify KD/SBMA candidate genes that are androgen dependent, and occur early in the disease process, properties which are promising for targeted therapeutics.
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Affiliation(s)
- Katherine Halievski
- Department of Psychology, University of Toronto Mississauga,
Mississauga, Ontario, Canada
| | - Kaiguo Mo
- Department of Psychology, University of Toronto Mississauga,
Mississauga, Ontario, Canada
| | - J. Timothy Westwood
- Department of Psychology, University of Toronto Mississauga,
Mississauga, Ontario, Canada
| | - Douglas A. Monks
- Department of Psychology, University of Toronto Mississauga,
Mississauga, Ontario, Canada
- * E-mail:
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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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27
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Chua JP, Reddy SL, Yu Z, Giorgetti E, Montie HL, Mukherjee S, Higgins J, McEachin RC, Robins DM, Merry DE, Iñiguez-Lluhí JA, Lieberman AP. Disrupting SUMOylation enhances transcriptional function and ameliorates polyglutamine androgen receptor-mediated disease. J Clin Invest 2015; 125:831-45. [PMID: 25607844 DOI: 10.1172/jci73214] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 11/25/2014] [Indexed: 12/20/2022] Open
Abstract
Expansion of the polyglutamine (polyQ) tract within the androgen receptor (AR) causes neuromuscular degeneration in individuals with spinobulbar muscular atrophy (SBMA). PolyQ AR has diminished transcriptional function and exhibits ligand-dependent proteotoxicity, features that have both been implicated in SBMA; however, the extent to which altered AR transcriptional function contributes to pathogenesis remains controversial. Here, we sought to dissociate effects of diminished AR function from polyQ-mediated proteotoxicity by enhancing the transcriptional activity of polyQ AR. To accomplish this, we bypassed the inhibitory effect of AR SUMOylation (where SUMO indicates small ubiquitin-like modifier) by mutating conserved lysines in the polyQ AR that are sites of SUMOylation. We determined that replacement of these residues by arginine enhances polyQ AR activity as a hormone-dependent transcriptional regulator. In a murine model, disruption of polyQ AR SUMOylation rescued exercise endurance and type I muscle fiber atrophy; it also prolonged survival. These changes occurred without overt alterations in polyQ AR expression or aggregation, revealing the favorable trophic support exerted by the ligand-activated receptor. Our findings demonstrate beneficial effects of enhancing the transcriptional function of the ligand-activated polyQ AR and indicate that the SUMOylation pathway may be a potential target for therapeutic intervention in SBMA.
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Renier KJ, Troxell-Smith SM, Johansen JA, Katsuno M, Adachi H, Sobue G, Chua JP, Sun Kim H, Lieberman AP, Breedlove SM, Jordan CL. Antiandrogen flutamide protects male mice from androgen-dependent toxicity in three models of spinal bulbar muscular atrophy. Endocrinology 2014; 155:2624-34. [PMID: 24742193 PMCID: PMC4060177 DOI: 10.1210/en.2013-1756] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a late-onset, progressive neurodegenerative disease linked to a polyglutamine (polyQ) expansion in the androgen receptor (AR). Men affected by SBMA show marked muscle weakness and atrophy, typically emerging midlife. Given the androgen-dependent nature of this disease, one might expect AR antagonists to have therapeutic value for treating SBMA. However, current work from animal models suggests otherwise, raising questions about whether polyQ-expanded AR exerts androgen-dependent toxicity through mechanisms distinct from normal AR function. In this study, we asked whether the nonsteroidal AR antagonist flutamide, delivered via a time-release pellet, could reverse or prevent androgen-dependent AR toxicity in three different mouse models of SBMA: the AR97Q transgenic (Tg) model, a knock-in (KI) model, and a myogenic Tg model. We find that flutamide protects mice from androgen-dependent AR toxicity in all three SBMA models, preventing or reversing motor dysfunction in the Tg models and significantly extending the life span in KI males. Given that flutamide effectively protects against androgen-dependent disease in three different mouse models of SBMA, our data are proof of principle that AR antagonists have therapeutic potential for treating SBMA in humans and support the notion that toxicity caused by polyQ-expanded AR uses at least some of the same mechanisms as normal AR before diverging to produce disease and muscle atrophy.
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Affiliation(s)
- Kayla J Renier
- Neuroscience Program (K.J.R., S.M.T.-S., S.M.B., C.L.J.), Michigan State University, E Lansing, Michigan 48824-1101; College of Medicine (J.A.J.), Central Michigan University, Mt Pleasant Michigan 48859; Department of Neurology (M.K., H.A., G.S.), Nagoya University Graduate School of Medicine, Nagoya, Japan 466-8550; and Department of Pathology (J.P.C., H.S.K., A.P.L.), University of Michigan, Ann Arbor, Michigan 48109
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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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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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31
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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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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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Ottem EN, Bailey DJ, Jordan CL, Breedlove SM. With a little help from my friends: androgens tap BDNF signaling pathways to alter neural circuits. Neuroscience 2012; 239:124-38. [PMID: 23262234 DOI: 10.1016/j.neuroscience.2012.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 12/03/2012] [Accepted: 12/05/2012] [Indexed: 12/20/2022]
Abstract
Gonadal androgens are critical for the development and maintenance of sexually dimorphic regions of the male nervous system, which is critical for male-specific behavior and physiological functioning. In rodents, the motoneurons of the spinal nucleus of the bulbocavernosus (SNB) provide a useful example of a neural system dependent on androgen. Unless rescued by perinatal androgens, the SNB motoneurons will undergo apoptotic cell death. In adulthood, SNB motoneurons remain dependent on androgen, as castration leads to somal atrophy and dendritic retraction. In a second vertebrate model, the zebra finch, androgens are critical for the development of several brain nuclei involved in song production in males. Androgen deprivation during a critical period during postnatal development disrupts song acquisition and dimorphic size-associated nuclei. Mechanisms by which androgens exert masculinizing effects in each model system remain elusive. Recent studies suggest that brain-derived neurotrophic factor (BDNF) may play a role in androgen-dependent masculinization and maintenance of both SNB motoneurons and song nuclei of birds. This review aims to summarize studies demonstrating that BDNF signaling via its tyrosine receptor kinase (TrkB) receptor may work cooperatively with androgens to maintain somal and dendritic morphology of SNB motoneurons. We further describe studies that suggest the cellular origin of BDNF is of particular importance in androgen-dependent regulation of SNB motoneurons. We review evidence that androgens and BDNF may synergistically influence song development and plasticity in bird species. Finally, we provide hypothetical models of mechanisms that may underlie androgen- and BDNF-dependent signaling pathways.
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Affiliation(s)
- E N Ottem
- Department of Biology, Northern Michigan University, Marquette, MI 49855, USA.
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Xiao H, Yu Z, Wu Y, Nan J, Merry DE, Sekiguchi JM, Ferguson DO, Lieberman AP, Dressler GR. A polyglutamine expansion disease protein sequesters PTIP to attenuate DNA repair and increase genomic instability. Hum Mol Genet 2012; 21:4225-36. [PMID: 22736030 DOI: 10.1093/hmg/dds246] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glutamine (Q) expansion diseases are a family of degenerative disorders caused by the lengthening of CAG triplet repeats present in the coding sequences of seemingly unrelated genes whose mutant proteins drive pathogenesis. Despite all the molecular evidence for the genetic basis of these diseases, how mutant poly-Q proteins promote cell death and drive pathogenesis remains controversial. In this report, we show a specific interaction between the mutant androgen receptor (AR), a protein associated with spinal and bulbar muscular atrophy (SBMA), and the nuclear protein PTIP (Pax Transactivation-domain Interacting Protein), a protein with an unusually long Q-rich domain that functions in DNA repair. Upon exposure to ionizing radiation, PTIP localizes to nuclear foci that are sites of DNA damage and repair. However, the expression of poly-Q AR sequesters PTIP away from radiation-induced nuclear foci. This results in sensitivity to DNA-damaging agents and chromosomal instabilities. In a mouse model of SBMA, evidence for DNA damage is detected in muscle cell nuclei and muscular atrophy is accelerated when one copy of the gene encoding PTIP is removed. These data provide a new paradigm for understanding the mechanisms of cellular degeneration observed in poly-Q expansion diseases.
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Affiliation(s)
- Hong Xiao
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
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35
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Current world literature. Curr Opin Endocrinol Diabetes Obes 2012; 19:233-47. [PMID: 22531108 DOI: 10.1097/med.0b013e3283542fb3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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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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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Banno H, Katsuno M, Suzuki K, Tanaka F, Sobue G. Pathogenesis and molecular targeted therapy of spinal and bulbar muscular atrophy (SBMA). Cell Tissue Res 2012; 349:313-20. [PMID: 22476656 DOI: 10.1007/s00441-012-1377-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/16/2012] [Indexed: 12/15/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is an adult-onset, X-linked motor neuron disease characterized by muscle atrophy, weakness, contraction fasciculations, and bulbar involvement. SBMA is caused by the expansion of a CAG triplet repeat, encoding a polyglutamine tract within the first exon of the androgen receptor (AR) gene. The histopathological finding in SBMA is the loss of lower motor neurons in the anterior horn of the spinal cord as well as in the brainstem motor nuclei. There is no established disease-modifying therapy for SBMA. Animal studies have revealed that the pathogenesis of SBMA depends on the level of serum testosterone, and that androgen deprivation mitigates neurodegeneration through inhibition of nuclear accumulation and/or stabilization of the pathogenic AR. Heat shock proteins, the ubiquitin-proteasome system and transcriptional regulation are also potential targets for development of therapy for SBMA. Among these therapeutic approaches, the luteinizing hormone-releasing hormone analogue, leuprorelin, prevents nuclear translocation of aberrant AR proteins, resulting in a significant improvement of disease phenotype in a mouse model of SBMA. In a phase 2 clinical trial of leuprorelin, the patients treated with this drug exhibited decreased mutant AR accumulation in scrotal skin biopsy. Phase 3 clinical trial showed the possibility that leuprorelin treatment is associated with improved swallowing function particularly in patients with a disease duration less than 10 years. These observations suggest that pharmacological inhibition of the toxic accumulation of mutant AR is a potential therapy for SBMA.
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Affiliation(s)
- Haruhiko Banno
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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Bricceno KV, Fischbeck KH, Burnett BG. Neurogenic and myogenic contributions to hereditary motor neuron disease. NEURODEGENER DIS 2012; 9:199-209. [PMID: 22327341 DOI: 10.1159/000335311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 11/23/2011] [Indexed: 12/21/2022] Open
Abstract
Spinal muscular atrophy and spinal and bulbar muscular atrophy are characterized by lower motor neuron loss and muscle atrophy. Although it is accepted that motor neuron loss is a primary event in disease pathogenesis, inherent defects in muscle may also contribute to the disease progression and severity. In this review, we discuss the relative contributions of primary pathological processes in the motor axons, neuromuscular junctions and muscle to disease manifestations. Characterizing these contributions helps us to better understand the disease mechanisms and to better target therapeutic intervention.
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Affiliation(s)
- Katherine V Bricceno
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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Ikenaka K, Katsuno M, Kawai K, Ishigaki S, Tanaka F, Sobue G. Disruption of axonal transport in motor neuron diseases. Int J Mol Sci 2012; 13:1225-1238. [PMID: 22312314 PMCID: PMC3269748 DOI: 10.3390/ijms13011225] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/11/2012] [Accepted: 01/16/2012] [Indexed: 12/29/2022] Open
Abstract
Motor neurons typically have very long axons, and fine-tuning axonal transport is crucial for their survival. The obstruction of axonal transport is gaining attention as a cause of neuronal dysfunction in a variety of neurodegenerative motor neuron diseases. Depletions in dynein and dynactin-1, motor molecules regulating axonal trafficking, disrupt axonal transport in flies, and mutations in their genes cause motor neuron degeneration in humans and rodents. Axonal transport defects are among the early molecular events leading to neurodegeneration in mouse models of amyotrophic lateral sclerosis (ALS). Gene expression profiles indicate that dynactin-1 mRNA is downregulated in degenerating spinal motor neurons of autopsied patients with sporadic ALS. Dynactin-1 mRNA is also reduced in the affected neurons of a mouse model of spinal and bulbar muscular atrophy, a motor neuron disease caused by triplet CAG repeat expansion in the gene encoding the androgen receptor. Pathogenic androgen receptor proteins also inhibit kinesin-1 microtubule-binding activity and disrupt anterograde axonal transport by activating c-Jun N-terminal kinase. Disruption of axonal transport also underlies the pathogenesis of spinal muscular atrophy and hereditary spastic paraplegias. These observations suggest that the impairment of axonal transport is a key event in the pathological processes of motor neuron degeneration and an important target of therapy development for motor neuron diseases.
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Affiliation(s)
- Kensuke Ikenaka
- Department of Neurology, Nagoya University Graduate School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; E-Mails: (K.I.); (K.K.); (F.T.)
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; E-Mails: (K.I.); (K.K.); (F.T.)
- Authors to whom correspondence should be addressed; E-Mails: (M.K.); (G.S.); Tel.: +81-52-744-2391 (M.K.); +81-52-744-2385 (G.S.); Fax: +81-52-744-2394 (M.K.); +81-52-744-2384 (G.S.)
| | - Kaori Kawai
- Department of Neurology, Nagoya University Graduate School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; E-Mails: (K.I.); (K.K.); (F.T.)
| | - Shinsuke Ishigaki
- Department of Neurology, Nagoya University Graduate School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; E-Mails: (K.I.); (K.K.); (F.T.)
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan; E-Mail: (S.I.)
| | - Fumiaki Tanaka
- Department of Neurology, Nagoya University Graduate School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; E-Mails: (K.I.); (K.K.); (F.T.)
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan; E-Mails: (K.I.); (K.K.); (F.T.)
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan; E-Mail: (S.I.)
- Authors to whom correspondence should be addressed; E-Mails: (M.K.); (G.S.); Tel.: +81-52-744-2391 (M.K.); +81-52-744-2385 (G.S.); Fax: +81-52-744-2394 (M.K.); +81-52-744-2384 (G.S.)
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Abstract
Gene products such as organelles, proteins and RNAs are actively transported to synaptic terminals for the remodeling of pre-existing neuronal connections and formation of new ones. Proteins described as molecular motors mediate this transport and utilize specialized cytoskeletal proteins that function as molecular tracks for the motor based transport of cargos. Molecular motors such as kinesins and dynein's move along microtubule tracks formed by tubulins whereas myosin motors utilize tracks formed by actin. Deficits in active transport of gene products have been implicated in a number of neurological disorders. We describe such disorders collectively as "transportopathies". Here we review current knowledge of critical components of active transport and their relevance to neurodegenerative diseases.
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