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Hsu JY, Jhang YL, Cheng PH, Chang YF, Mao SH, Yang HI, Lin CW, Chen CM, Yang SH. The Truncated C-terminal Fragment of Mutant ATXN3 Disrupts Mitochondria Dynamics in Spinocerebellar Ataxia Type 3 Models. Front Mol Neurosci 2017; 10:196. [PMID: 28676741 PMCID: PMC5476786 DOI: 10.3389/fnmol.2017.00196] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/02/2017] [Indexed: 01/24/2023] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3), known as Machado-Joseph disease, is an autosomal dominant disease caused by an abnormal expansion of polyglutamine in ATXN3 gene, leading to neurodegeneration in SCA3 patients. Similar to other neurodegenerative diseases, the dysfunction of mitochondria is observed to cause neuronal death in SCA3 patients. Based on previous studies, proteolytic cleavage of mutant ATXN3 is found to produce truncated C-terminal fragments in SCA3 models. However, whether these truncated mutant fragments disturb mitochondrial functions and result in pathological death is still unclear. Here, we used neuroblastoma cell and transgenic mouse models to examine the effects of truncated mutant ATXN3 on mitochondria functions. In different models, we observed truncated mutant ATXN3 accelerated the formation of aggregates, which translocated into the nucleus to form intranuclear aggregates. In addition, truncated mutant ATXN3 caused more mitochondrial fission, and decreased the expression of mitochondrial fusion markers, including Mfn-1 and Mfn-2. Furthermore, truncated mutant ATXN3 decreased the mitochondrial membrane potential, increased reactive oxygen species and finally increased cell death rate. In transgenic mouse models, truncated mutant ATXN3 also led to more mitochondrial dysfunction, neurodegeneration and cell death in the cerebellums. This study supports the toxic fragment hypothesis in SCA3, and also provides evidence that truncated mutant ATXN3 is severer than full-length mutant one in vitro and in vivo.
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Affiliation(s)
- Jung-Yu Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung UniversityTainan, Taiwan.,Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Yu-Ling Jhang
- Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Pei-Hsun Cheng
- Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Yu-Fan Chang
- Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Su-Han Mao
- Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Han-In Yang
- Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Chia-Wei Lin
- Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Chuan-Mu Chen
- Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing UniversityTaichung, Taiwan
| | - Shang-Hsun Yang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung UniversityTainan, Taiwan.,Department of Physiology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
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Her LS, Lin JY, Fu MH, Chang YF, Li CL, Tang TY, Jhang YL, Chang CY, Shih MC, Cheng PH, Yang SH. The Differential Profiling of Ubiquitin-Proteasome and Autophagy Systems in Different Tissues before the Onset of Huntington's Disease Models. Brain Pathol 2014; 25:481-90. [PMID: 25178567 DOI: 10.1111/bpa.12191] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/18/2014] [Indexed: 12/19/2022] Open
Abstract
Huntington's disease (HD) is a genetic and neurodegenerative disease, leading to motor and cognitive dysfunction in HD patients. At cellular level, this disease is caused by the accumulation of mutant huntingtin (HTT) in different cells, and finally results in the dysfunction of different cells. To clean these mutant proteins, ubiquitin-proteasome system (UPS) and autophagy system are two critical pathways in the brain; however, little is known in other peripheral tissues. As mutant HTT affects different tissues progressively and might influence the UPS and autophagy pathways at early stages, we attempted to examine two clearance systems in HD models before the onset. Here, in vitro results showed that the accumulation of UPS signals with time was observed obviously in neuroblastoma and kidney cells, not in other cells. In HD transgenic mice, we observed the impairment of UPS, but not autophagy, over time in the cortex and striatum. In heart and muscle tissues, disturbance of autophagy was observed, whereas dysfunction of UPS was displayed in liver and lung. These results suggest that two protein clearance pathways are disturbed differentially in different tissues before the onset of HD, and enhancement of protein clearance at early stages might provide a potential stratagem to alleviate the progression of HD.
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Affiliation(s)
- Lu-Shiun Her
- Department of Life Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Jian-Yu Lin
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Mu-Hui Fu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Fan Chang
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Chia-Ling Li
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ting-Yu Tang
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Ling Jhang
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Chih-Yi Chang
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Meng-Chi Shih
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Pei-Hsun Cheng
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Shang-Hsun Yang
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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