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Lo CH, Pandey NK, Lim CKW, Ding Z, Tao M, Thomas DD, Langen R, Sachs JN. Discovery of Small Molecule Inhibitors of Huntingtin Exon 1 Aggregation by FRET-Based High-Throughput Screening in Living Cells. ACS Chem Neurosci 2020; 11:2286-2295. [PMID: 32568514 DOI: 10.1021/acschemneuro.0c00226] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Huntington's disease (HD) is the most common inherited neurodegenerative disorder and one of the nine polyglutamine (polyQ) diseases. HD is characterized by the pathological aggregation of the misfolded huntingtin exon 1 protein (Httex1) with abnormally long polyQ expansion due to genetic mutation. While there is currently no effective treatment for HD, inhibition of aggregate formation represents a direct approach in mediating the toxicity associated with Httex1 misfolding. To exploit this therapeutic window, we engineered two fluorescence resonance energy transfer (FRET) based biosensors that monitor the aggregation of Httex1 with different expanded Q-lengths (Q39 and Q72) in living cells. These FRET biosensors, together with a high-precision fluorescence lifetime detection platform, enable high-throughput screening of small molecules that target Httex1 aggregation. We found six small molecules that decreased the FRET of the biosensors and reduced Httex1-Q72-induced neuronal cytotoxicity in N2a cells with nanomolar potency. Using advanced SPR and EPR techniques, we confirmed that the compounds directly bind to Httex1 fibrils and inhibit aggregate formation. This strategy in targeting the Httex1 aggregates can be applicable to other proteins involved in polyQ related diseases.
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Affiliation(s)
- Chih Hung Lo
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Nitin K. Pandey
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, United States
| | - Colin Kin-Wye Lim
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Zhipeng Ding
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Meixin Tao
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, United States
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Photonic Pharma LLC, Minneapolis, Minnesota 55410, United States
| | - Ralf Langen
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, United States
| | - Jonathan N. Sachs
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Gao W, Chen R, Xie N, Tang D, Zhou B, Wang D. Duloxetine-Induced Neural Cell Death and Promoted Neurite Outgrowth in N2a Cells. Neurotox Res 2020; 38:859-870. [PMID: 32415528 PMCID: PMC7591439 DOI: 10.1007/s12640-020-00216-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/15/2020] [Accepted: 04/22/2020] [Indexed: 02/04/2023]
Abstract
Duloxetine is a clinical drug that is primarily used for treatment of depression and pain, but it has side effects of addiction and tolerance. Cytochrome P450 (CYP) is its metabolic enzyme, and the drug's biofunction results from its neuro-protective effect in animal and cell models. We aimed to investigate the duloxetine-induced neural cytotoxicity effect and its performance in an N2a cell neurite outgrowth model. Cell death was assessed as cell viability using a Cell Count Kit-8 and further evaluated using bright-field images, propidium iodide (PI) and annexin V staining, colony-formation analysis, TUNEL staining of the cells, and biochemical testing. N2a cells were committed to differentiation by serum withdrawal and RA induction, and the neurite outgrowth was evaluated as the number of differentiated cells, longest neurite length, and average neurite length. Cell cycle analysis, PI and annexin V staining, mRNA expression, and biochemical testing were used to evaluate the drug effects on differentiation. The induction of neural cell death by duloxetine was not affected by classic cell death inhibitors but was promoted by the CYP inducer rifampicin. N2a cell neurite outgrowth was promoted by duloxetine via reduction of the CYP2D6 and MDA levels and induction of Bdnf protein levels. Duloxetine induces neural cell death through effects on CYP and promotes N2a cell neurite outgrowth by regulating CYP, Bdnf protein, and the intracellular lipid peroxidation level.
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Affiliation(s)
- Wanli Gao
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Center for DAMP Biology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China.,Department of Neurology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China
| | - Rui Chen
- Department of Reproductive, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China
| | - Nan Xie
- Department of Oral Pathology, Guanghua School of Stomatology, Research Institute of Stomatology, Guangdong Province Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, 510055, Guangdong, People's Republic of China
| | - Daolin Tang
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Borong Zhou
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Center for DAMP Biology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China. .,Department of Neurology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China.
| | - Ding Wang
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Center for DAMP Biology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China. .,Experimental Department of Institute of Gynecology and Obstetrics, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510510, People's Republic of China.
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3
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Ghosh R, Wood-Kaczmar A, Dobson L, Smith EJ, Sirinathsinghji EC, Kriston-Vizi J, Hargreaves IP, Heaton R, Herrmann F, Abramov AY, Lam AJ, Heales SJ, Ketteler R, Bates GP, Andre R, Tabrizi SJ. Expression of mutant exon 1 huntingtin fragments in human neural stem cells and neurons causes inclusion formation and mitochondrial dysfunction. FASEB J 2020; 34:8139-8154. [PMID: 32329133 PMCID: PMC8432155 DOI: 10.1096/fj.201902277rr] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 03/27/2020] [Accepted: 04/02/2020] [Indexed: 11/11/2022]
Abstract
Robust cellular models are key in determining pathological mechanisms that lead to neurotoxicity in Huntington's disease (HD) and for high throughput pre‐clinical screening of potential therapeutic compounds. Such models exist but mostly comprise non‐human or non‐neuronal cells that may not recapitulate the correct biochemical milieu involved in pathology. We have developed a new human neuronal cell model of HD, using neural stem cells (ReNcell VM NSCs) stably transduced to express exon 1 huntingtin (HTT) fragments with variable length polyglutamine (polyQ) tracts. Using a system with matched expression levels of exon 1 HTT fragments, we investigated the effect of increasing polyQ repeat length on HTT inclusion formation, location, neuronal survival, and mitochondrial function with a view to creating an in vitro screening platform for therapeutic screening. We found that expression of exon 1 HTT fragments with longer polyQ tracts led to the formation of intra‐nuclear inclusions in a polyQ length‐dependent manner during neurogenesis. There was no overt effect on neuronal viability, but defects of mitochondrial function were found in the pathogenic lines. Thus, we have a human neuronal cell model of HD that may recapitulate some of the earliest stages of HD pathogenesis, namely inclusion formation and mitochondrial dysfunction.
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Affiliation(s)
- Rhia Ghosh
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Alison Wood-Kaczmar
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Lucianne Dobson
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Edward J Smith
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Eva C Sirinathsinghji
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Janos Kriston-Vizi
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | | | - Robert Heaton
- School of Pharmacy, Liverpool John Moores University, Liverpool, UK
| | | | - Andrey Y Abramov
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Amanda J Lam
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Simon J Heales
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Robin Ketteler
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Gillian P Bates
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Ralph Andre
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Sarah J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
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Mohara M, Kawasaki T, Owada R, Imai T, Kanetaka H, Izumi SI, Tsukiyama K, Nakamura K. Restoration from polyglutamine toxicity after free electron laser irradiation of neuron-like cells. Neurosci Lett 2018; 685:42-49. [PMID: 30044955 DOI: 10.1016/j.neulet.2018.07.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 07/05/2018] [Accepted: 07/19/2018] [Indexed: 01/21/2023]
Abstract
Proteins containing an expanded polyglutamine tract tend to aggregate, leading to the neuronal damage observed in polyglutamine diseases. We recently reported that free electron laser (FEL) irradiation markedly dissociates naked polyglutamine aggregates as well as the aggregate in the 293 T cells. In the present study, we investigated whether FEL irradiation of neuron-like cells with polyglutamine aggregates would restore the cellular damage and dysfunction. The aggregated polyglutamine peptides induced neurite retraction of differentiated SH-SY5Y cells. Upon FEL irradiation, the polyglutamine aggregates in the SH-SY5Y cells were dissociated, and the shorter length of individual neurite, fewer number of neurites per cell and shorter total length of neurite by polyglutamine were inhibited. Same results were essentially obtained in PC12 cells. Moreover, when FEL irradiation was applied to undifferentiated SH-SY5Y cells, the deficits in neuron-like differentiation seen in expanded polyglutamine peptide-containing cells were also rescued. Thus, FEL irradiation restored both the damage and differentiation caused by polyglutamine in neuron-like cells.
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Affiliation(s)
- Miho Mohara
- Gunma University Graduate School of Health Sciences, 3-39-22, Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Takayasu Kawasaki
- IR Free Electron Laser Research Center, Research Institute for Science and Technology, Organization for Research Advancement, Tokyo University of Science, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Ryuji Owada
- Gunma University Graduate School of Health Sciences, 3-39-22, Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Takayuki Imai
- IR Free Electron Laser Research Center, Research Institute for Science and Technology, Organization for Research Advancement, Tokyo University of Science, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Hiroyasu Kanetaka
- Laison Center for Innovative Dentistry, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Shin-Ichi Izumi
- Department of Physical Medicine and Rehabilitation, Tohoku University Graduate School of Biomedical Engineering, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Koichi Tsukiyama
- IR Free Electron Laser Research Center, Research Institute for Science and Technology, Organization for Research Advancement, Tokyo University of Science, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Kazuhiro Nakamura
- Gunma University Graduate School of Health Sciences, 3-39-22, Showa-machi, Maebashi, Gunma, 371-8511, Japan.
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Ghosh DK, Roy A, Ranjan A. Aggregation-prone Regions in HYPK Help It to Form Sequestration Complex for Toxic Protein Aggregates. J Mol Biol 2018; 430:963-986. [DOI: 10.1016/j.jmb.2018.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/09/2018] [Accepted: 02/10/2018] [Indexed: 11/24/2022]
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Gatto RG, Chu Y, Ye AQ, Price SD, Tavassoli E, Buenaventura A, Brady ST, Magin RL, Kordower JH, Morfini GA. Analysis of YFP(J16)-R6/2 reporter mice and postmortem brains reveals early pathology and increased vulnerability of callosal axons in Huntington's disease. Hum Mol Genet 2015; 24:5285-98. [PMID: 26123489 DOI: 10.1093/hmg/ddv248] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/23/2015] [Indexed: 11/14/2022] Open
Abstract
Cumulative evidence indicates that the onset and severity of Huntington's disease (HD) symptoms correlate with connectivity deficits involving specific neuronal populations within cortical and basal ganglia circuits. Brain imaging studies and pathological reports further associated these deficits with alterations in cerebral white matter structure and axonal pathology. However, whether axonopathy represents an early pathogenic event or an epiphenomenon in HD remains unknown, nor is clear the identity of specific neuronal populations affected. To directly evaluate early axonal abnormalities in the context of HD in vivo, we bred transgenic YFP(J16) with R6/2 mice, a widely used HD model. Diffusion tensor imaging and fluorescence microscopy studies revealed a marked degeneration of callosal axons long before the onset of motor symptoms. Accordingly, a significant fraction of YFP-positive cortical neurons in YFP(J16) mice cortex were identified as callosal projection neurons. Callosal axon pathology progressively worsened with age and was influenced by polyglutamine tract length in mutant huntingtin (mhtt). Degenerating axons were dissociated from microscopically visible mhtt aggregates and did not result from loss of cortical neurons. Interestingly, other axonal populations were mildly or not affected, suggesting differential vulnerability to mhtt toxicity. Validating these results, increased vulnerability of callosal axons was documented in the brains of HD patients. Observations here provide a structural basis for the alterations in cerebral white matter structure widely reported in HD patients. Collectively, our data demonstrate a dying-back pattern of degeneration for cortical projection neurons affected in HD, suggesting that axons represent an early and potentially critical target for mhtt toxicity.
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Affiliation(s)
- Rodolfo G Gatto
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Rm 578 M/C 512, Chicago, IL 60612, USA
| | - Yaping Chu
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA and
| | - Allen Q Ye
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Steven D Price
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Rm 578 M/C 512, Chicago, IL 60612, USA
| | - Ehsan Tavassoli
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Rm 578 M/C 512, Chicago, IL 60612, USA
| | - Andrea Buenaventura
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Rm 578 M/C 512, Chicago, IL 60612, USA
| | - Scott T Brady
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Rm 578 M/C 512, Chicago, IL 60612, USA
| | - Richard L Magin
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Jeffrey H Kordower
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA and
| | - Gerardo A Morfini
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Rm 578 M/C 512, Chicago, IL 60612, USA,
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Lin YS, Cheng TH, Chang CP, Chen HM, Chern Y. Enhancement of brain-type creatine kinase activity ameliorates neuronal deficits in Huntington's disease. Biochim Biophys Acta Mol Basis Dis 2013; 1832:742-53. [DOI: 10.1016/j.bbadis.2013.02.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/22/2013] [Accepted: 02/05/2013] [Indexed: 12/27/2022]
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An in vitro perspective on the molecular mechanisms underlying mutant huntingtin protein toxicity. Cell Death Dis 2012; 3:e382. [PMID: 22932724 PMCID: PMC3434668 DOI: 10.1038/cddis.2012.121] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Huntington's disease (HD) is a devastating neurodegenerative disorder whose main hallmark is brain atrophy. However, several peripheral organs are considerably affected and their symptoms may, in fact, manifest before those resulting from brain pathology. HD is of genetic origin and caused by a mutation in the huntingtin gene. The mutated protein has detrimental effects on cell survival, but whether the mutation leads to a gain of toxic function or a loss of function of the altered protein is still highly controversial. Most currently used in vitro models have been designed, to a large extent, to investigate the effects of the aggregation process in neuronal-like cells. However, as the pathology involves several other organs, new in vitro models are critically needed to take into account the deleterious effects of mutant huntingtin in peripheral tissues, and thus to identify new targets that could lead to more effective clinical interventions in the early course of the disease. This review aims to present current in vitro models of HD pathology and to discuss the knowledge that has been gained from these studies as well as the new in vitro tools that have been developed, which should reflect the more global view that we now have of the disease.
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Cheng YC, Chen TA, Chen CY, Liang CM, Liang SM. 3'poly-G-tailed ODNs inhibit F-spondin to induce cell death and neurite retraction in rat embryonic neurons. Mol Neurobiol 2012; 45:536-49. [PMID: 22592270 DOI: 10.1007/s12035-012-8275-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Accepted: 05/01/2012] [Indexed: 10/28/2022]
Abstract
The effects and mechanism of action of oligodeoxyribonucleotides containing CpG motif (CpG-ODNs) on neuron cells are largely unexamined. Here, we found that CpG-A ODNs but not other types of CpG-ODNs induced neurite retraction and cell apoptosis of rat embryonic neurons in a TLR9-independent manner. These effects of CpG-A ODNs were primarily due to the poly-guanosine at the 3' terminus (3'G-ODNs). Pull-down analysis showed that 3'G-ODNs associated with transcription factor Y-BOX1 (YB-1) to facilitate the translocation of YB-1 into the nucleus via the nuclear localizing sequence of YB-1. YB-1 then interacted with the promoter of F-spondin directly at -45 and -1,375 sites as demonstrated by chromatin immunoprecipitation (ChIP) analysis. Binding of YB-1 to F-spondin promoter resulted in downregulation of F-spondin expression. Overexpression of F-spondin rescued the cell death and neurite retraction induced by 3'G-ODNs in embryonic neuron cells. Taken together, these findings suggest that 3'G-ODNs enhance nucleus YB-1 to inhibit F-spondin leading to cell death and neurite retraction of embryonic neuron cells.
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Affiliation(s)
- Yung-Chih Cheng
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
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Sellamuthu S, Shin BH, Han HE, Park SM, Oh HJ, Rho SH, Lee YJ, Park WJ. An engineered viral protease exhibiting substrate specificity for a polyglutamine stretch prevents polyglutamine-induced neuronal cell death. PLoS One 2011; 6:e22554. [PMID: 21799895 PMCID: PMC3140514 DOI: 10.1371/journal.pone.0022554] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 06/23/2011] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Polyglutamine (polyQ)-induced protein aggregation is the hallmark of a group of neurodegenerative diseases, including Huntington's disease. We hypothesized that a protease that could cleave polyQ stretches would intervene in the initial events leading to pathogenesis in these diseases. To prove this concept, we aimed to generate a protease possessing substrate specificity for polyQ stretches. METHODOLOGY/PRINCIPAL FINDINGS Hepatitis A virus (HAV) 3C protease (3CP) was subjected to engineering using a yeast-based method known as the Genetic Assay for Site-specific Proteolysis (GASP). Analysis of the substrate specificity revealed that 3CP can cleave substrates containing glutamine at positions P5, P4, P3, P1, P2', or P3', but not substrates containing glutamine at the P2 or P1' positions. To accommodate glutamine at P2 and P1', key residues comprising the active sites of the S2 or S1' pockets were separately randomized and screened. The resulting sets of variants were combined by shuffling and further subjected to two rounds of randomization and screening using a substrate containing glutamines from positions P5 through P3'. One of the selected variants (Var26) reduced the expression level and aggregation of a huntingtin exon1-GFP fusion protein containing a pathogenic polyQ stretch (HttEx1(97Q)-GFP) in the neuroblastoma cell line SH-SY5Y. Var26 also prevented cell death and caspase 3 activation induced by HttEx1(97Q)-GFP. These protective effects of Var26 were proteolytic activity-dependent. CONCLUSIONS/SIGNIFICANCE These data provide a proof-of-concept that proteolytic cleavage of polyQ stretches could be an effective modality for the treatment of polyQ diseases.
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Affiliation(s)
- Saravanan Sellamuthu
- College of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
| | - Bae Hyun Shin
- College of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
| | - Hye-Eun Han
- College of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
| | - Sang Min Park
- College of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
| | - Hye Jin Oh
- College of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
| | - Seong-Hwan Rho
- Physics Institute, University of Freiburg, Freiburg, Germany
| | - Yong Jae Lee
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Woo Jin Park
- College of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
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Kim S, Leal SS, Ben Halevy D, Gomes CM, Lev S. Structural requirements for VAP-B oligomerization and their implication in amyotrophic lateral sclerosis-associated VAP-B(P56S) neurotoxicity. J Biol Chem 2010; 285:13839-49. [PMID: 20207736 DOI: 10.1074/jbc.m109.097345] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The integral endoplasmic reticulum (ER)-membrane protein VAP-B interacts with various lipid-transfer/binding proteins containing an FFAT motif through its N-terminal MSP domain. A genetic mutation within its MSP domain, P56S, was identified in familial forms of motor neuron diseases. This mutation induces the formation of insoluble VAP-B(P56S) protein aggregates by an unknown mechanism. In this study, we defined the structural requirements for VAP-B oligomerization and demonstrated their contribution for VAP-B(P56S) aggregation and neurotoxicity. We show that the oligomerization of VAP-B is mainly mediated by its coiled-coil domain and that the GXXXG dimerization motif within the transmembrane domain mediates transmembrane domains self-association but is insufficient to drive VAP-B oligomerization. We further show that the oligomerization of the wild-type VAP-B is independent of its MSP domain. However, we found that the P56S mutation induces conformational changes within the MSP domain and facilitates its propensity to aggregate by exposing hydrophobic patches to the solvent. These conformational changes have no direct effect on FFAT binding. Rather, they enhance VAP-B(P56S) oligomerization driven by the combined contributions of the coiled-coil and the transmembrane domains, thereby preventing accessibility to FFAT-binding site, facilitating the production of VAP-B(P56S)-insoluble aggregates and consequently its neurotoxicity. These results shed light on the mechanism by which VAP-B(P56S) aggregates are formed and induce familial motor neuron diseases.
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Affiliation(s)
- SoHui Kim
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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HSP40 ameliorates impairment of insulin secretion by inhibiting huntingtin aggregation in a HD pancreatic beta cell model. Biosci Biotechnol Biochem 2009; 73:1787-92. [PMID: 19661690 DOI: 10.1271/bbb.90147] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Diabetes frequently develops in Huntington's disease patients. Here, we found that mutant huntingtin forms aggregates in the cytoplasm and reduces insulin secretion from huntingtin transfected pancreatic beta cell lines, NIT-1 cells. Activity of the pro-survival factor, Akt, is enhanced in these cells, which might improve the maintenance of insulin content. Overexpression of heat shock protein 40 (HSP40) inhibits aggregation, reverses impaired insulin release, and blocks the enhancement of Akt activity. These results suggest that impairment of beta cells is mostly linked with the aggregate formation of mutant huntingtin, and that HSP40 ameliorates the malfunction of pancreatic beta cells by inhibiting aggregation.
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