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Richardson K, Sengupta M, Sujkowski A, Libohova K, Harris AC, Wessells R, Merry DE, Todi SV. A phenotypically robust model of spinal and bulbar muscular atrophy in Drosophila. J Neurosci Res 2024; 102:e25278. [PMID: 38284836 DOI: 10.1002/jnr.25278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/14/2023] [Accepted: 11/05/2023] [Indexed: 01/30/2024]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an X-linked disorder that affects males who inherit the androgen receptor (AR) gene with an abnormal CAG triplet repeat expansion. The resulting protein contains an elongated polyglutamine (polyQ) tract and causes motor neuron degeneration in an androgen-dependent manner. The precise molecular sequelae of SBMA are unclear. To assist with its investigation and the identification of therapeutic options, we report here a new model of SBMA in Drosophila melanogaster. We generated transgenic flies that express the full-length, human AR with a wild-type or pathogenic polyQ repeat. Each transgene is inserted into the same safe harbor site on the third chromosome of the fly as a single copy and in the same orientation. Expression of pathogenic AR, but not of its wild-type variant, in neurons or muscles leads to consistent, progressive defects in longevity and motility that are concomitant with polyQ-expanded AR protein aggregation and reduced complexity in neuromuscular junctions. Additional assays show adult fly eye abnormalities associated with the pathogenic AR species. The detrimental effects of pathogenic AR are accentuated by feeding flies the androgen, dihydrotestosterone. This new, robust SBMA model can be a valuable tool toward future investigations of this incurable disease.
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Affiliation(s)
- Kristin Richardson
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Medha Sengupta
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania, USA
| | - Alyson Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Autumn C Harris
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
- Maximizing Access to Science Careers Program, Wayne State University, Detroit, Michigan, USA
| | - Robert Wessells
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Diane E Merry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
- Maximizing Access to Science Careers Program, Wayne State University, Detroit, Michigan, USA
- Department of Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA
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Sengupta M, Pluciennik A, Merry DE. The role of ubiquitination in spinal and bulbar muscular atrophy. Front Mol Neurosci 2022; 15:1020143. [PMID: 36277484 PMCID: PMC9583669 DOI: 10.3389/fnmol.2022.1020143] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neurodegenerative and neuromuscular genetic disease caused by the expansion of a polyglutamine-encoding CAG tract in the androgen receptor (AR) gene. The AR is an important transcriptional regulator of the nuclear hormone receptor superfamily; its levels are regulated in many ways including by ubiquitin-dependent degradation. Ubiquitination is a post-translational modification (PTM) which plays a key role in both AR transcriptional activity and its degradation. Moreover, the ubiquitin-proteasome system (UPS) is a fundamental component of cellular functioning and has been implicated in diseases of protein misfolding and aggregation, including polyglutamine (polyQ) repeat expansion diseases such as Huntington’s disease and SBMA. In this review, we discuss the details of the UPS system, its functions and regulation, and the role of AR ubiquitination and UPS components in SBMA. We also discuss aspects of the UPS that may be manipulated for therapeutic effect in SBMA.
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Guilherme JPLF, V Shikhova Y, R Dondukovskaya R, A Topanova A, A Semenova E, V Astratenkova I, Ahmetov II. Androgen receptor gene microsatellite polymorphism is associated with muscle mass and strength in bodybuilders and power athlete status. Ann Hum Biol 2021; 48:142-149. [PMID: 33900145 DOI: 10.1080/03014460.2021.1919204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND The androgen receptor (AR) gene contains a polymorphic trinucleotide (CAG) microsatellite repeat sequence (short or long alleles) that has been associated with fat-free mass in untrained men, which needs to be replicated in athletic cohorts. AIM The purpose of this study was to explore the AR (CAG)n polymorphism in trained individuals. SUBJECTS AND METHODS A total of 61 professional bodybuilders (40 males, 21 females), 73 elite male sprinters and weightlifters and 186 male controls were enrolled in this study. The influence of the AR (CAG)n polymorphism on muscle mass and strength was assessed in bodybuilders, while the frequencies of AR (CAG)n alleles were compared between power athletes and non-athletes. RESULTS The polymorphism was associated with anthropometric and strength measurements in bodybuilders of both genders. Those with ≥21 CAG repeats (i.e. carriers of long alleles) exhibited greater (p < 0.05) body mass index, absolute muscle mass, arm/thigh circumference and upper/lower limb strength compared to those with <21 CAG repeats. Furthermore, carriers of ≥21 CAG repeats were more frequent among power athletes compared to controls (p = 0.0076). CONCLUSIONS Long alleles of the AR (CAG)n polymorphism were associated with greater muscle mass and strength in bodybuilders, and power athlete status.
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Affiliation(s)
- João Paulo L F Guilherme
- Laboratory of Applied Nutrition and Metabolism, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Yulia V Shikhova
- Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, St Petersburg, Russia
| | - Rimma R Dondukovskaya
- Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, St Petersburg, Russia.,Weider College of Fitness and Bodybuilding, St Petersburg, Russia
| | - Alexandra A Topanova
- Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, St Petersburg, Russia.,Institute of Medical Education, Almazov National Medical Research Centre, St Petersburg, Russia
| | - Ekaterina A Semenova
- Department of Molecular Biology and Genetics, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia.,Sport Technology Research Center, Volga Region State University of Physical Culture, Sport and Tourism, Kazan, Russia
| | - Irina V Astratenkova
- Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, St Petersburg, Russia.,Department of Physiology, St Petersburg State University, St Petersburg, Russia
| | - Ildus I Ahmetov
- Sports Genetics Laboratory, St Petersburg Research Institute of Physical Culture, St Petersburg, Russia.,Department of Physical Education, Plekhanov Russian University of Economics, Moscow, Russia.,Laboratory of Molecular Genetics, Kazan State Medical University, Kazan, Russia.,Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by a polyglutamine (polyQ) expansion in the androgen receptor (AR). Despite the fact that the monogenic cause of SBMA has been known for nearly 3 decades, there is no effective treatment for this disease, underscoring the complexity of the pathogenic mechanisms that lead to a loss of motor neurons and muscle in SBMA patients. In the current review, we provide an overview of the system-wide clinical features of SBMA, summarize the structure and function of the AR, discuss both gain-of-function and loss-of-function mechanisms of toxicity caused by polyQ-expanded AR, and describe the cell and animal models utilized in the study of SBMA. Additionally, we summarize previously conducted clinical trials which, despite being based on positive results from preclinical studies, proved to be largely ineffective in the treatment of SBMA; nonetheless, these studies provide important insights as researchers develop the next generation of therapies.
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Affiliation(s)
- Frederick J Arnold
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 411E Jefferson Alumni Hall, 1020 Locust Street, Philadelphia, Pennsylvania, 19107, USA
| | - Diane E Merry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 411E Jefferson Alumni Hall, 1020 Locust Street, Philadelphia, Pennsylvania, 19107, USA.
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Abstract
This review explores the presence and functions of polyglutamine (polyQ) in viral proteins. In mammals, mutations in polyQ segments (and CAG repeats at the nucleotide level) have been linked to neural disorders and ataxias. PolyQ regions in normal human proteins have documented functional roles, in transcription factors and, more recently, in regulating autophagy. Despite the high frequency of polyQ repeats in eukaryotic genomes, little attention has been given to the presence or possible role of polyQ sequences in virus genomes. A survey described here revealed that polyQ repeats occur rarely in RNA viruses, suggesting that they have detrimental effects on virus replication at the nucleotide or protein level. However, there have been sporadic reports of polyQ segments in potyviruses and in reptilian nidoviruses (among the largest RNA viruses known). Conserved polyQ segments are found in the regulatory control proteins of many DNA viruses. Variable length polyQ tracts are found in proteins that contribute to transmissibility (cowpox A-type inclusion protein (ATI)) and control of latency (herpes viruses). New longer-read sequencing methods, using original biological samples, should reveal more details on the presence and functional role of polyQ in viruses, as well as the nucleotide regions that encode them. Given the known toxic effects of polyQ repeats, the role of these segments in neurovirulent and tumorigenic viruses should be further explored.
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Swift-Gallant A, Monks DA. Androgenic mechanisms of sexual differentiation of the nervous system and behavior. Front Neuroendocrinol 2017; 46:32-45. [PMID: 28455096 DOI: 10.1016/j.yfrne.2017.04.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 04/21/2017] [Accepted: 04/24/2017] [Indexed: 01/23/2023]
Abstract
Testicular androgens are the major endocrine factor promoting masculine phenotypes in vertebrates, but androgen signaling is complex and operates via multiple signaling pathways and sites of action. Recently, selective androgen receptor mutants have been engineered to study androgenic mechanisms of sexual differentiation of the nervous system and behavior. The focus of these studies has been to evaluate androgenic mechanisms within the nervous system by manipulating androgen receptor conditionally in neural tissues. Here we review both the effects of neural loss of AR function as well as the effects of neural overexpression of AR in relation to global AR mutants. Although some studies have conformed to our expectations, others have proved challenging to assumptions underlying the dominant hypotheses. Notably, these studies have called into question both the primacy of direct, neural mechanisms and also the linearity of the relationship between androgenic dose and sexual differentiation of brain and behavior.
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Affiliation(s)
- A Swift-Gallant
- Department of Psychology, University of Toronto, 100 St. George Street, Toronto, ON M5S 3G3, Canada; Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON L5L 1C6, Canada
| | - D A Monks
- Department of Psychology, University of Toronto, 100 St. George Street, Toronto, ON M5S 3G3, Canada; Department of Cells and Systems Biology, University of Toronto, 100 St. George Street, Toronto, ON M5S 3G3, Canada; Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON L5L 1C6, Canada.
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