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Truant R, Harding RJ, Neuman K, Maiuri T. Revisiting huntingtin activity and localization signals in the context of protein structure. J Huntingtons Dis 2024; 13:419-430. [PMID: 39973382 DOI: 10.1177/18796397241295303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2025]
Abstract
Protein localization signals and activity motifs have been defined within huntingtin since 2003. Advances in technology in protein structure determination by cryo-electron microscopy (EM) have led to 2.6 Å resolution structures of huntingtin and HAP40 for the majority of the protein, although structure of the amino terminus with the polyglutamine expansion remains elusive in the context of full-length huntingtin. Recent advances in protein modeling using neural network algorithms trained on a database of known protein structures has resulted in structure predictions that are useful for researchers but need experimental validation. Here, we use both structures solved by cryo-EM as well as modeling centered around experimental structural data to retrospectively revisit huntingtin protein localization signals identified prior to the cryo-EM and AI-enabled structural revolutions. We interrogate these models as well as put forward testable hypotheses of allosteric changes in huntingtin and how they could be affected by polyglutamine expansion. We also extended this methodology to another polyglutamine disease protein, ataxin-1, expanded in Spinocerebellar Ataxia Type 1 (SCA1).
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Affiliation(s)
- Ray Truant
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Rachel J Harding
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
- Structural Genomics Consortium, University of Toronto, Toronto, Canada
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Kaitlyn Neuman
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Tamara Maiuri
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
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Son S, Bowie LE, Maiuri T, Hung CLK, Desmond CR, Xia J, Truant R. High-mobility group box 1 links sensing of reactive oxygen species by huntingtin to its nuclear entry. J Biol Chem 2018; 294:1915-1923. [PMID: 30538129 DOI: 10.1074/jbc.ra117.001440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 12/04/2018] [Indexed: 11/06/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative, age-onset disorder caused by a CAG DNA expansion in exon 1 of the HTT gene, resulting in a polyglutamine expansion in the huntingtin protein. Nuclear accumulation of mutant huntingtin is a hallmark of HD, resulting in elevated mutant huntingtin levels in cell nuclei. Huntingtin is normally retained at the endoplasmic reticulum via its N17 amphipathic α-helix domain but is released by oxidation of Met-8 during reactive oxygen species (ROS) stress. Huntingtin enters the nucleus via an importin β1- and 2-dependent proline-tyrosine nuclear localization signal (PY-NLS), which has a unique intervening sequence in huntingtin. Here, we have identified the high-mobility group box 1 (HMGB1) protein as an interactor of the intervening sequence within the PY-NLS. Nuclear levels of HMGB1 positively correlated with varying levels of nuclear huntingtin in both HD and normal human fibroblasts. We also found that HMGB1 interacts with the huntingtin N17 region and that this interaction is enhanced by the presence of ROS and phosphorylation of critical serine residues in the N17 region. We conclude that HMGB1 is a huntingtin N17/PY-NLS ROS-dependent interactor, and this protein bridging is essential for relaying ROS sensing by huntingtin to its nuclear entry during ROS stress. ROS may therefore be a critical age-onset stress that triggers nuclear accumulation of mutant huntington in Huntington's disease.
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Affiliation(s)
- Susie Son
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Laura E Bowie
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Tamara Maiuri
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Claudia L K Hung
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Carly R Desmond
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Jianrun Xia
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Ray Truant
- From the Department of Biochemistry and Biomedical Research, McMaster University, Hamilton, Ontario L8S 4L8, Canada
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Xu Z, Chen J, Shi J, Zhao J, Wang J, Ji Y, Han L, Zhu L, Li X, Zhang D. Upregulated Expression of Karyopherin α2 is Involved in Neuronal Apoptosis Following Intracerebral Hemorrhage in Adult Rats. Cell Mol Neurobiol 2016; 36:755-65. [PMID: 26340948 PMCID: PMC11482370 DOI: 10.1007/s10571-015-0258-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/25/2015] [Indexed: 12/19/2022]
Abstract
Karyopherin α2 (KPNA2) plays a central role in nucleocytoplasmic transport. It is involved in controlling the flow of genetic information and the modulation of diverse cellular activities. Here we explored the KPNA2's roles during the pathophysiological processes of intracerebral hemorrhage (ICH). An ICH rat model was built and evaluated according to behavioral testing. Using Western blot, immunohistochemistry, and immunofluorescence, significant upregulation of KPNA2 was found in neurons in brain areas surrounding the hematoma following ICH. Increasing KPNA2 level was found to be accompanied by the upregulation of active caspase-3, Bax, and decreased expression of Bcl-2. Besides, KPNA2 co-localized well with active caspase-3 in neurons, indicating its potential role in neuronal apoptosis. What's more, knocking down KPNA2 by RNA-interference in PC12 cells reduced active caspase-3 expression. Thus, KPNA2 may play a role in promoting the brain secondary damage following ICH.
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Affiliation(s)
- Zhiwei Xu
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Jianping Chen
- Surgical Comprehensive Laboratory, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Jiansheng Shi
- Surgical Comprehensive Laboratory, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Jianmei Zhao
- Surgical Comprehensive Laboratory, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Jun Wang
- Surgical Comprehensive Laboratory, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Yuhong Ji
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Lijian Han
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Liang Zhu
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Xiaohong Li
- Surgical Comprehensive Laboratory, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China.
| | - Dongmei Zhang
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Medical College of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China.
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Gao X, Campbell WA, Chaibva M, Jain P, Leslie AE, Frey SL, Legleiter J. Cholesterol Modifies Huntingtin Binding to, Disruption of, and Aggregation on Lipid Membranes. Biochemistry 2015; 55:92-102. [PMID: 26652744 DOI: 10.1021/acs.biochem.5b00900] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disease caused by abnormally long CAG-repeats in the huntingtin gene that encode an expanded polyglutamine (polyQ) domain near the N-terminus of the huntingtin (htt) protein. Expanded polyQ domains are directly correlated to disease-related htt aggregation. Htt is found highly associated with a variety of cellular and subcellular membranes that are predominantly comprised of lipids. Since cholesterol homeostasis is altered in HD, we investigated how varying cholesterol content modifies the interactions between htt and lipid membranes. A combination of Langmuir trough monolayer techniques, vesicle permeability and binding assays, and in situ atomic force microscopy were used to directly monitor the interaction of a model, synthetic htt peptide and a full-length htt-exon1 recombinant protein with model membranes comprised of total brain lipid extract (TBLE) and varying amounts of exogenously added cholesterol. As the cholesterol content of the membrane increased, the extent of htt insertion decreased. Vesicles containing extra cholesterol were resistant to htt-induced permeabilization. Morphological and mechanical changes in the bilayer associated with exposure to htt were also drastically altered by the presence of cholesterol. Disrupted regions of pure TBLE bilayers were grainy in appearance and associated with a large number of globular aggregates. In contrast, morphological changes induced by htt in bilayers enriched in cholesterol were plateau-like with a smooth appearance. Collectively, these observations suggest that the presence and amount of cholesterol in lipid membranes play a critical role in htt binding and aggregation on lipid membranes.
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Affiliation(s)
- Xiang Gao
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States
| | - Warren A Campbell
- Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania 17325, United States
| | - Maxmore Chaibva
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States
| | - Pranav Jain
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States
| | - Ashley E Leslie
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States
| | - Shelli L Frey
- Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania 17325, United States
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.,NanoSAFE, P.O. Box 6223, West Virginia University, Morgantown, West Virginia 26506, United States.,The Center for Neurosciences, West Virginia University, Morgantown, West Virginia 26505, United States
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Bowles KR, Brooks SP, Dunnett SB, Jones L. Huntingtin Subcellular Localisation Is Regulated by Kinase Signalling Activity in the StHdhQ111 Model of HD. PLoS One 2015; 10:e0144864. [PMID: 26660732 PMCID: PMC4679340 DOI: 10.1371/journal.pone.0144864] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 11/23/2015] [Indexed: 12/03/2022] Open
Abstract
Huntington's disease is a neurodegenerative disorder characterised primarily by motor abnormalities, and is caused by an expanded polyglutamine repeat in the huntingtin protein. Huntingtin dynamically shuttles between subcellular compartments, and the mutant huntingtin protein is mislocalised to cell nuclei, where it may interfere with nuclear functions, such as transcription. However, the mechanism by which mislocalisation of mutant huntingtin occurs is currently unknown. An immortalised embryonic striatal cell model of HD (StHdhQ111) was stimulated with epidermal growth factor in order to determine whether the subcellular localisation of huntingtin is dependent on kinase signalling pathway activation. Aberrant phosphorylation of AKT and MEK signalling pathways was identified in cells carrying mutant huntingtin. Activity within these pathways was found to contribute to the regulation of huntingtin and mutant huntingtin localisation, as well as to the expression of immediate-early genes. We propose that altered kinase signalling is a phenotype of Huntington's disease that occurs prior to cell death; specifically, that altered kinase signalling may influence huntingtin localisation, which in turn may impact upon nuclear processes such as transcriptional regulation. Aiming to restore the balance of activity between kinase signalling networks may therefore prove to be an effective approach to delaying Huntington's disease symptom development and progression.
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Affiliation(s)
- Kathryn R. Bowles
- Institute of Psychological Medicine and Clinical Neurosciences, MRC centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Hadyn Ellis building, Maindy Road, Cardiff University, Cardiff CF24 4HQ, Wales, United Kingdom
| | - Simon P. Brooks
- The Brain Repair Group, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales, United Kingdom
| | - Stephen B. Dunnett
- The Brain Repair Group, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, Wales, United Kingdom
| | - Lesley Jones
- Institute of Psychological Medicine and Clinical Neurosciences, MRC centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Hadyn Ellis building, Maindy Road, Cardiff University, Cardiff CF24 4HQ, Wales, United Kingdom
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Senapedis WT, Baloglu E, Landesman Y. Clinical translation of nuclear export inhibitors in cancer. Semin Cancer Biol 2014; 27:74-86. [DOI: 10.1016/j.semcancer.2014.04.005] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 04/10/2014] [Indexed: 01/18/2023]
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