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The Role of the Protein Quality Control System in SBMA. J Mol Neurosci 2015; 58:348-64. [PMID: 26572535 DOI: 10.1007/s12031-015-0675-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/01/2015] [Indexed: 12/13/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) or Kennedy's disease is an X-linked disease associated with the expansion of the CAG triplet repeat present in exon 1 of the androgen receptor (AR) gene. This results in the production of a mutant AR containing an elongated polyglutamine tract (polyQ) in its N-terminus. Interestingly, the ARpolyQ becomes toxic only after its activation by the natural androgenic ligands, possibly because of aberrant androgen-induced conformational changes of the ARpolyQ, which generate misfolded species. These misfolded ARpolyQ species must be cleared from motoneurons and muscle cells, and this process is mediated by the protein quality control (PQC) system. Experimental evidence suggested that failure of the PQC pathways occurs in disease, leading to ARpolyQ accumulation and toxicity in the target cells. In this review, we summarized the overall impact of mutant and misfolded ARpolyQ on the PQC system and described how molecular chaperones and the degradative pathways (ubiquitin-proteasome system (UPS), the autophagy-lysosome pathway (ALP), and the unfolded protein response (UPR), which activates the endoplasmic reticulum-associated degradation (ERAD)) are differentially affected in SBMA. We also extensively and critically reviewed several molecular and pharmacological approaches proposed to restore a global intracellular activity of the PQC system. Collectively, these data suggest that the fine and delicate equilibrium existing among the different players of the PQC system could be restored in a therapeutic perspective by the synergic/additive activities of compounds designed to tackle sequential or alternative steps of the intracellular defense mechanisms triggered against proteotoxic misfolded species.
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Trinucleotide repeats and protein folding and disease: the perspective from studies with the androgen receptor. Future Sci OA 2015; 1:FSO47. [PMID: 28031874 PMCID: PMC5137883 DOI: 10.4155/fso.15.47] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The androgen receptor (AR), a ligand activated transcription factor plays a number of roles in reproduction, homeostasis and pathogenesis of disease. It has two major polymorphic sequences; a polyglutamine and a polyglycine repeat that determine the length of the protein and influence receptor folding, structure and function. Here, we review the role the folding of the AR plays in the pathogenesis of spinal-bulbar muscular atrophy (SBMA), a neuromuscular degenerative disease arising from expansion of the polyglutamine repeat. We discuss current management for SBMA patients and how research on AR structure function may lead to future drug treatments.
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Tirabassi G, Cignarelli A, Perrini S, delli Muti N, Furlani G, Gallo M, Pallotti F, Paoli D, Giorgino F, Lombardo F, Gandini L, Lenzi A, Balercia G. Influence of CAG Repeat Polymorphism on the Targets of Testosterone Action. Int J Endocrinol 2015; 2015:298107. [PMID: 26421011 PMCID: PMC4572434 DOI: 10.1155/2015/298107] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 08/09/2015] [Indexed: 01/11/2023] Open
Abstract
In the last decade, ample evidence has demonstrated the growing importance of androgen receptor (AR) CAG repeat polymorphism in andrology. This genetic parameter is able to condition the peripheral effects of testosterone and therefore to influence male sexual function and fertility, cardiovascular risk, body composition, bone metabolism, the risk of prostate and testicular cancer, the psychiatric status, and the onset of neurodegenerative disorders. In this review, we extensively discuss the literature data and identify a role for AR CAG repeat polymorphism in conditioning the systemic testosterone effects. In particular, our main purpose was to provide an updated text able to shed light on the many and often contradictory findings reporting an influence of CAG repeat polymorphism on the targets of testosterone action.
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Affiliation(s)
- Giacomo Tirabassi
- Division of Endocrinology, Department of Clinical and Molecular Sciences, Umberto I Hospital, Polytechnic University of Marche, Via Conca 71, 60126 Ancona, Italy
| | - Angelo Cignarelli
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Sebastio Perrini
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Nicola delli Muti
- Division of Endocrinology, Department of Clinical and Molecular Sciences, Umberto I Hospital, Polytechnic University of Marche, Via Conca 71, 60126 Ancona, Italy
| | - Giorgio Furlani
- Division of Endocrinology, Department of Clinical and Molecular Sciences, Umberto I Hospital, Polytechnic University of Marche, Via Conca 71, 60126 Ancona, Italy
| | - Mariagrazia Gallo
- Laboratory of Seminology-Sperm Bank, Department of Experimental Medicine, University of Rome “La Sapienza”, Viale del Policlinico 155, 00161 Rome, Italy
| | - Francesco Pallotti
- Laboratory of Seminology-Sperm Bank, Department of Experimental Medicine, University of Rome “La Sapienza”, Viale del Policlinico 155, 00161 Rome, Italy
| | - Donatella Paoli
- Laboratory of Seminology-Sperm Bank, Department of Experimental Medicine, University of Rome “La Sapienza”, Viale del Policlinico 155, 00161 Rome, Italy
| | - Francesco Giorgino
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Francesco Lombardo
- Laboratory of Seminology-Sperm Bank, Department of Experimental Medicine, University of Rome “La Sapienza”, Viale del Policlinico 155, 00161 Rome, Italy
| | - Loredana Gandini
- Laboratory of Seminology-Sperm Bank, Department of Experimental Medicine, University of Rome “La Sapienza”, Viale del Policlinico 155, 00161 Rome, Italy
| | - Andrea Lenzi
- Laboratory of Seminology-Sperm Bank, Department of Experimental Medicine, University of Rome “La Sapienza”, Viale del Policlinico 155, 00161 Rome, Italy
| | - Giancarlo Balercia
- Division of Endocrinology, Department of Clinical and Molecular Sciences, Umberto I Hospital, Polytechnic University of Marche, Via Conca 71, 60126 Ancona, Italy
- *Giancarlo Balercia:
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