研究生: |
楊淑婷 Shu-Ting Yang |
---|---|
論文名稱: |
第十七型脊髓小腦共濟失調症 (SCA17)體外之藥物篩檢模式暨TBP與HMGB1蛋白質交互作用之研究 In vitro compound screening for SCA17 and interaction analysis between expanded TBP and HMGB1 |
指導教授: |
李桂楨
Lee, Guey-Jen |
學位類別: |
碩士 Master |
系所名稱: |
生命科學系 Department of Life Science |
論文出版年: | 2010 |
畢業學年度: | 98 |
語文別: | 中文 |
論文頁數: | 59 |
中文關鍵詞: | 脊髓小腦共濟失調症 |
英文關鍵詞: | SCA17 |
論文種類: | 學術論文 |
相關次數: | 點閱:85 下載:2 |
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脊髓小腦共濟失調症(SCAs)中的第1、2、3、6、7、17型和亨丁頓氏舞蹈症(HD)等神經退化性疾病,起因於特定基因上不正常的polyQ擴增,導致蛋白質的構型改變,在細胞中產生聚集(aggregation),並透過不正常的蛋白質交互作用,影響細胞的功能。第17型SCA (SCA17)是由於位在TATA binding protein (TBP)基因上的CAG三核苷不正常擴增所導致。TBP為一轉錄起始因子,會與其他蛋白因子交互作用來調節基因的表現。TBP N端區域的polyQ長度,正常人約在25到42間,病人約在43到66間。本研究的第一目的為探討polyQ擴增是否會影響TBP和HMGB1的結合。利用原核E. coli及真核HEK293T表現的蛋白質,分別以石英晶體微量天平(QCM)與GST pull down方法,分析HMGB1與TBP蛋白間的交互作用,結果發現TBP蛋白上polyQ長度的增加,會減弱其與HMGB1蛋白的交互作用。真核HEK293T的HMGB1與TBP共表現及免疫共沉澱實驗,亦顯示TBP與HMGB1的交互作用,隨polyQ長度的增加而減弱。本研究的第二目的為藉測量thioflavin T與擴增polyQ結合產生的螢光量變化,來篩選可能抑制polyQ聚集的化合物。與剛果紅相較,所篩選的31種化合物抑制polyQ聚集的效果皆不顯著。
Neurodegenerative diseases such as hereditary spinocerebellar ataxias (SCAs) type 1, 2, 3, 6, 7, 17 and Huntington's disease are linked to abnormally expanded polyglutamine (polyQ) tract in the respective proteins. The polyQ expansions cause a conformational change in the polypeptide to promote misfolding and aggregation of the disease protein. The expanded polyQ protein may also acquire a toxic function through aberrant protein interactions. The disease-causing gene in SCA17 has been identified as polyQ expansion in the TATA-box binding protein (TBP) gene. TBP is a transcription initiation factor. TBP interacts with other protein factors to regulate gene expression. PolyQ length in TBP N terminal domain ranges from 25~42 in normal population and 43~66 in SCA17. The first aim of this study is to investigate if the polyQ expansion affects HMGB1 binding. By using quartz crystal microbalance (QCM) and GST pull down assay, both E. coli and HEK293T expressed proteins were used to study the interactions between HMGB1 and TBP carrying 20~61 polyQ tract. The results suggest the negative association of polyQ length and HMGB1-TBP interaction. The in vivo length-dependent negative association between TBP and HMGB1 interaction was also suggested by co-expression and co-immunoprecipitation. The second aim of this study is to screen effective chemical compounds which may inhibit polyQ aggregation using thioflavin T binding assay. Among the 31 compounds examined, none displayed effective aggregation inhibition as compared to congo red.
陳襄銘(2007)。脊髓小腦運動失調症:SCA2、SCA4的遺傳檢測及擴增SCA17 TBP蛋白與HMGB1蛋白的交互作用分析。國立台灣師範大學生命科學系九十六學年度碩士論文。
黃慧茹(2007)。第十七型脊髓小腦運動失調症:遺傳檢測及發展生化暨酵母菌的藥物篩檢模式。國立台灣師範大學生命科學系九十六學年度碩士論文。
李麗卿(2009)。Spinocerebellar ataxia 17 (SCA17) pathogenic mechanisms: Chaperones function and misfolding proteins caused by the expanded polyglutamine in TATA-binding protein
Agnello D, Wang H, Yang H, Tracey KJ, Ghezzi P. HMGB-1, a DNA-binding protein with cytokine activity, induces brain TNF and IL-β production, and mediates anorexia and taste aversion. Cytokine 2002;18:231-236.
Agresti A, Bianchi ME. HMGB proteins and gene expression. Curr Opin Genet Dev 2003;13:170-178.
Andersson U, Wang H, Palmblad K, Aveberger AC, Bloom O, Erlandsson-Harris H, Janson A, Kokkola R, Zhang M, Yang H, Tracey KJ. High mobility group 1 protein (HMG-1) stimulates proinflammatory cytokine synthesis in human monocytes. J Exp Med 1996;192:565-570.
Barton S, Jacak R, Khare SD, Ding F, Dokholyan NV. The length dependence of the polyQ-mediated protein aggregation. J Biol Chem. 2007;282:25487-25492.
Bennett EJ, Shaler TA, Woodman B, Ryu KY, Zaitseva TS, Becker CH, Bates GP, Schulman H, Kopito RR. Global changes to the ubiquitin system in Huntington's disease. Nature 2007;448:704-708.
Bonaldi T, Längst G, Strohner R, Becker PB, Bianchi ME. The DNA chaperone HMGB1 facilitates ACF/CHRAC-dependent nucleosome sliding. EMBO J 2006;21:6865-6873.
Boonyaratanakornkit V, Melvin V, Prendergast P, Altmann M, Ronfani L, Bianchi ME, Taraseviciene L, Nordeen SK, Allegretto EA, Edwards DP. High-mobility group chromatin proteins 1 and 2 functionally interact with steroid hormone receptors to enhance their DNA binding in vitro and transcriptional activity in mammalian cells. Mol Cell Biol 1998;18:4471-4487.
Bruni AC, Takahashi-Fujigasaki J, Maltecca F, Foncin JF, Servadio A, Casari G, D'Adamo P, Maletta R, Curcio SA, De Michele G, Filla A, El Hachimi KH, Duyckaerts C. Behavioral disorder, dementia, ataxia, and rigidity in a large family with TATA box-binding protein mutation. Arch Neurol 2004;61:1314-1320.
Das D, Scovell WM. The binding interaction of HMG-1 with the TATA-binding protein/TATA complex. J Biol Chem 2001;276:32597-32605.
David G, Abbas N, Stevanin G, Duerr A, Yvert G, Cancel G, Weber C, Imbert G, Saudou F, Antoniou E, Drabkin H, Gemmill R, Giunti P, Benomar A, Brice A. Cloning of the SCA7 gene reveals a highly unstable CAG repeat expansion. Nat Genet 1997;17:65-70.
De Michele G, Maltecca F, Carella M, Volpe G, Orio M, De Falco A, Gombia S, Servadio A, Casari G, Filla A, Bruni A. Dementia, ataxia, extrapyramidal features, and epilepsy: phenotype spectrum in two Italian families with spinocerebellar ataxia type 17. Neurol Sci 2003;24:166-167.
De Virgilio C, Buerckert N, Bell W, Jenoe P, Boller T, Wiemken A. Disruption of TPS2, the gene encoding the 100-kDa subunit of the trehalose-6-phosphate synthase/phosphatase complex in Saccharomyces cerevisiae, causes accumulation of trehalose-6-phosphate and loss of trehalose-6-phosphate phosphatase activity. Eur J Biochem1993;212:315-323.
Dedeoglu A, Kubilus JK, Jeitner TM, Matson SA, Bogdanov M, Kowall NW, Matson WR, Cooper AJ, Ratan RR, Beal MF, Hersch SM, Ferrante RJ. Therapeutic effects of cystamine in a murine model of Huntington's disease. J Neurosci 2002;22:8942-8950.
Dorval V, Fraser PE. SUMO on the road to neurodegeneration. Biochim Biophys Acta 2007;1773:694-706.
Ferrante RJ, Andreassen OA, Jenkins BG, Dedeoglu A, Kuemmerle S, Kubilus JK, Kaddurah-Daouk R, Hersch SM, Beal MF. Neuroprotective effects of creatine in a transgenic mouse model of Huntington's disease. J Neurosci 2000;20:4389-4397.
Ferrante RJ, Kubilus JK, Lee J, Ryu H, Beesen A, Zucker B, Smith K, Kowall NW, Ratan RR, Luthi-Carter R, Hersch SM. Histone deacetylase inhibition by sodium butyrate chemotherapy ameliorates the neurodegenerative phenotype in Huntington's disease mice. J Neurosci 2003;23:9418-9427.
Friedman MJ, Shah AG, Fang ZH, Ward EG, Warren ST, Li S, Li XJ. Polyglutamine domain modulates the TBP-TFIIB interaction: implications for its normal function and neurodegeneration. Nat Neurosci 2007;10:1519-1528
Friedman MJ, Wang CE, Li XJ, Li S. Polyglutamine expansion reduces the association of TBP with DNA and induces DNA binding- independent neurotoxicity. J Biol Chem 2008;283:8283-8290.
Fujigasaki H, Martin JJ, De Deyn PP, Camuzat A, Deffond D, Stevanin G, Dermaut B, Van Broeckhoven C, Dürr A, Brice A. CAG repeat expansion in the TATA box-binding protein gene causes autosomal dominant cerebellar ataxia. Brain 2001;124:1939-1947.
Gostout B, Liu Q, Sommer SS. "Cryptic" repeating triplets of purines and pyrimidines (cRRY(i)) are frequent and polymorphic: analysis of coding cRRY(i) in the proopiomelanocortin (POMC) and TATA-binding protein (TBP) genes. Am J Hum Genet 1993;52:1182-1190.
Guazzi S, Strangio A, Franzi AT, Bianchi ME. HMGB1, an architectural chromatin protein and an extracellular signaling factor, has a spatially and temporally restricted expression pattern in mouse brain. Gene Expr 2003;3:29-33.
Gusella JF and MacDonald ME. Molecular genetics: unmasking polyglutamine triggers in neurodegenerative disease. Nat Neurosci 2000;1:109-115.
Hamuro L, Zhang G, Tucker TJ, Self C, Strittmatter WJ, Burke JR. Optimization of a polyglutamine aggregation inhibitor peptide (QBP1) using a thioflavin T fluorescence assay. Assay Drug Dev Technol 2007;5:629-636.
Heiser V, Engemann S, Bröcker W, Dunkel I, Boeddrich A, Waelter S, Nordhoff E, Lurz R, Schugardt N, Rautenberg S, Herhaus C, Barnickel G, Böttcher H, Lehrach H, Wanker EE. Identification of benzothiazoles as potential polyglutamine aggregation inhibitors of Huntington's disease by using an automated filter retardation assay. Proc Natl Acad Sci USA 2002;99 Suppl 4:16400-16406.
Hernandez D, Hanson M, Singleton A, Gwinn-Hardy K, Freeman J, Ravina B, Doheny D, Gallardo M, Weiser R, Hardy J, Singleton A. Mutation at the SCA17 locus is not a common cause of parkinsonism. Parkinsonism Relat Disord 2003;9:317-320.
Hochheimer A, Tjian R. Diversified transcription initiation complexes expand promoter selectivity and tissue-specific gene expression. Genes Dev 2003;1309-1320.
Hockly E, Richon VM, Woodman B, Smith DL, Zhou X, Rosa E, Sathasivam K, Ghazi-Noori S, Mahal A, Lowden PA, Steffan JS, Marsh JL, Thompson LM, Lewis CM, Marks PA, Bates GP. Suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, ameliorates motor deficits in a mouse model of Huntington's disease. Proc Natl Acad Sci USA 2003;100:2041-2046.
Hottiger T, de Virgilio C, Hall MN, Boller T, Wiemken A. The role of trehalose synthesis for the acquisition of thermotolerance in yeast. II. Physiological concentrations of trehalose increase the thermal stability of proteins in vitro. Eur J Biochem.1994;219:187–193.
Imbert G, Saudou F, Yvert G, Devys D, Trottier Y, Garnier JM, Weber C, Mandel JL, Cancel G, Abbas N, Durr A, Didierjean O, Stevanin G, Agid Y, Brice A. Cloning of the gene for spinocerebellar ataxia 2 reveals a locus with high sensitivity to expanded CAG/glutamine repeats. Nat Genet 1996;14:285-291.
Kawaguchi Y, Okamoto T, Taniwaki M, Aizawa M, Inoue M, Katayama S, Kawakami H, Nakamura S, Kakizuka A. CAG expansions in a novel gene for machado-joseph disease at chromosome 14q32.1. Nat Genet 1994;8:221-228.
Kim JB, Sig Choi J, Yu YM, Nam K, Piao CS, Kim SW, Lee MH, Han P L, Park JS, Lee JK. HMGB1, a novel cytokine-like mediator linking acute neuronal death and delayed neuroinflammation in the postischemic brain. J Neurosci 2006;26:6413-6421.
Koide R, Ikeuchi T, Onodera O, Tanaka H, Igarashi S, Endo K, Takahashi H, Kondo R, Ishikawa A, Hayashi T, Saito M, Tomoda A, Miike T, Naito H, Ikuta F, Tsuji S. Unstable expansion of CAG repeat in hereditary dentatorubral-pallidoluysian atrophy (DRPLA). Nat Genet 1994;6:9-13.
Koide R, Kobayashi S, Shimohata T, Ikeuchi T, Maruyama M, Saito M, Yamada M, Takahashi H, Tsuji S. A neurological disease caused by an expanded CAG trinucleotide repeat in the TATA-binding protein gene: A new polyglutamine disease? Hum Mol Genet 1999;8:2047-2053.
Lange SS, Mitchell DL, Vasquez KM. High mobility group protein B1 enhances DNA repair and chromatin modification after DNA damage. Proc Natl Acad Sci USA 2008;105:10320-10325.
Lasek K, Lencer R, Gaser C, Hagenah J, Walter U, Wolters A, Kock N, Steinlechner S, Nagel M, Zühlke C, Nitschke MF, Brockmann K, Klein C, Rolfs A, Binkofski F. Morphological basis for the spectrum of clinical deficits in spinocerebellar ataxia 17 (SCA17). Brain 2006;129:2341-2352.
Lendel C, Bolognesi B, Wahlström A, Dobson CM, Gräslund A. Detergent-like interaction of Congo red with the amyloid beta peptide. Biochemistry 2010;49:1358-1360.
Lindsten K, Menéndez-Benito V, Masucci1 MG, Dantuma1 NP. A transgenic mouse model of the ubiquitin/proteasome system. Nat Biotechnol 2003;21:897-902.
Maltecca F, Filla A, Castaldo I, Coppola G, Fragassi NA, Carella M, Bruni A, Cocozza S, Casari G, Servadio A, De Michele G. Intergenerational instability and marked anticipation in SCA-17. Neurology 2003;61:1441-1443.
Matilla-Dueñas A, Sánchez I, Corral-Juan M, Dávalos A, Alvarez R, Latorre P. Cellular and molecular pathways triggering neurodegeneration in the spinocerebellar ataxias. Cerebellum 2009 Nov 5. [Epub ahead of print]
Maynard CJ, Böttcher C, Ortega Z, Smith R, Florea BI, Díaz-Hernández M, Brundin P, Overkleeft HS, Li JY, Lucas JJ, Dantuma NP. Accumulation of ubiquitin conjugates in a polyglutamine disease model occurs without global ubiquitin/proteasome system impairment. Proc Natl Acad Sci USA 2009;106:13986-13991.
Nagafuchi S, Yanagisawa H, Sato K, Shirayama T, Ohsaki E, Bundo M, Takeda T, Tadokoro K, Kondo I, Murayama N, Tanaka Y, Kikushima H, Umino K, Kurosawa H, Furukawa T, Nihei K, Inoue T, Sano A,. Komure O, Takahashi M, Yoshizawa T, Kanazawa I, Yamada M. Dentatorubral and pallidoluysian atrophy expansion of an unstable CAG trinucleotide on chromosome 12p. Nat Genet 1994;6:14-18.
Nagai Y, Tucker T, Ren H, Kenan DJ, Henderson BS, Keene JD, Strittmatter WJ, Burke JR. Inhibition of polyglutamine protein aggregation and cell death by novel peptides identified by phage display screening. J Biol Chem 2000;275:10437-10442.
Nagai Y, Fujikake N, Ohno K, Higashiyama H, Popiel HA, Rahadian J, Yamaguchi M, Strittmatter WJ, Burke JR, Toda T. Prevention of polyglutamine oligomerization and neurodegeneration by the peptide inhibitor QBP1 in Drosophila. Hum Mol Genet 2003;12:1253-1259.
Nightingale K, Dimitrov S, Reeves R, Wolffe AP. Evidence for a shared structural role for HMG1 and linker histones B4 and H1 in organizing chromatin. EMBO J 1996;15:548-561.
O’Connor KA, Hansen MK, Pugh CR, Deak MM, Biedenkapp JC, Milligan ED, Johnson JD, Wang H, Maier SF, Tracey KJ, Watkins LR. Further characterization of High mobility group box 1 (HMGB1) as a proinflammatory cytokine: central nervous system effects. Cytokine 2003;24:254-265.
Okazawa H. Polyglutamine diseases: a transcription disorder? Cell Mol Life Sci 2003;60:1427-1439.
Orr HT, Chung M, Banfi S, Kwiatkowski TJ Jr, Servadio A, Beaudet AL, McCall AE, Duvick LA, Ranum LPW, Zoghbi HY. Expansion of an unstable trinucleotide CAG repeat in spinocerebellar ataxia type 1. Nat Genet 1993;4:221-226.
Pedrazzi M, Patrone M, Passalacqua M, Ranzato E, Colamassaro D, Sparatore B, Pontremoli S, Melloni E. Selective proinflammatory activation of astrocytes by high-mobility group box 1 protein signaling. J Immunol 2007;179:8525-8532.
Perutz MF, Johnson T, Suzuki M, Finch JT. Glutamine repeats as polar zippers: their possible role in inherited neurodegenerative diseases. Proc Natl Acad Sci USA 1994;91:5355-5358.
Pulst SM, Nechiporuk A, Nechiporuk T, Gispert S, Chen X, Lopes-Cendes I, Pearlman S, Starkman S, Orozoco-Diaz G, Lunkes A, DeJong P, Rouleau GA, Auburger G, Sahba S. Moderate expansion of a normally biallelic trinucleotide repeat in spinocerebellar ataxia type 2. Nat Genet 1996;14:269-276.
Qi ML, Tagawa K, Enokido Y, Yoshimura N, Wada Y, Watase K, Ishiura S, Kanazawa I, Botas J, Saitoe M, Wanker EE, Okazawa H. Proteome analysis of soluble nuclear proteins reveals that HMGB1/2 suppress genotoxic stress in polyglutamine diseases. Nat Cell Biol 2007;9:402-414.
Rangachari V, Reed DK, Moore BD, Rosenberry TL. Secondary structure and interfacial aggregation of amyloid-beta(1-40) on sodium dodecyl sulfate micelles. Biochemistry 2006;45:8639-8648.
Riley BE, Zoghbi HY, Orr HT. SUMOylation of the polyglutamine repeat protein, ataxin-1, is dependent on a functional nuclear localization signal. J Biol Chem 2005;280:21942-21948.
Rolfs A, Koeppen AH, Bauer I, Bauer P, Buhlmann S, Topka H, Schöls L, Riess O. Clinical features and neuropathology of autosomal dominant spinocerebellar ataxia (SCA17). Ann Neurol 2003;54:367-375.
Sauerbrey G. Verwendung von Schwingquarzen zur Wägung dünner Schichten und zur Mikrowägung. Z Phys 1959;155:206.
Shiota M, Izumi H, Miyamoto N, Onitsuka T, Kashiwagi E, Kidani A, Hirano G, Takahashi M, Ono M, Kuwano M, Naito S, Sasaguri Y, Kohno K. Ets regulates peroxiredoxin1 and 5 expressions through their interaction with the high-mobility group protein B1. Cancer Sci 2008;99:1950-1959.
Silveira I, Miranda C, Guimaraes L, Moreira MC, Alonso I, Mendonça P, Ferro A, Pinto-Basto J, Coelho J, Ferreirinha F, Poirier J, Parreira E, Vale J, Januário C, Barbot C, Tuna A, Barros J, Koide R, Tsuji S, Holmes SE, Margolis RL, Jardim L, Pandolfo M, Coutinho P, Sequeiros J. Trinucleotide repeats in 202 families with ataxia: a small expanded (CAG)n allele at the SCA17 locus. Arch Neurol 2002;59:623-629.
Smith DL, Portier R, Woodman B, Hockly E, Mahal A, Klunk WE, Li XJ, Wanker E, Murray KD, Bates GP. Inhibition of polyglutamine aggregation in R6/2 HD brain slices-complex dose-response profiles. Neurobiol Dis 2001;8:1017-1026.
Stevanin G, Fujigasaki H, Lebre AS, Camuzat A, Jeannequin C, Dode C, Takahashi J, San C, Bellance R, Brice A, Durr A. Huntington’s disease-like phenotype due to trinucleotide repeat expansions in the TBP and JPH3 genes. Brain 2003;126:1599-1603.
Stros M, Polanská E, Struncová S, Pospísilová S.HMGB1 and HMGB2 proteins up-regulate cellular expression of human topoisomerase IIalpha. Nucleic Acids Res 2009;2070-2086.
Swanson PC. Fine structure and activity of discrete RAG-HMG complexes on V(D)J recombination signals. Mol Cell Biol 2002;22:1340-1351.
Takahashi-Fujigasaki J, Arai K, Funata N, Fujigasaki H. SUMOylation substrates in neuronal intranuclear inclusion disease. Neuropathol Appl Neurobiol 2006;32:92-100.
Takata K, Kitamura Y, Kakimura J, Shibagaki K, Tsuchiya D, Taniguchi T, Smith MA, Perry G, Shimohama S. Role of high mobility group protein-1 (HMG1) in amyloid-β homeostasis. Biochem Biophys Res Commun 2003;301:699-703.
Takata K, Kitamura Y, Tsuchiya D, Kawasaki T, Taniguchi T, Shimohama S. High mobility group box protein-1 inhibits microglial Aβ clearance and enhances Aβ neurotoxicity. J Neurosci Res 2004;78:880-891.
Tanaka M, Machida Y, Niu S, Ikeda T, Jana NR, Doi H, Kurosawa M, Nekooki M, Nukina N. Trehalose alleviates polyglutamine- mediated pathology in a mouse model of Huntington disease. Nat Med 2004;10:148-154.
Tanaka M, Machida Y, Nukina N. A novel therapeutic strategy for polyglutamine disease by stabilizing aggregation-prone proteins with small molecules. J Mol Med 2005;83:343-352.
Teive HA. Spinocerebellar ataxias. Arq Neuropsiquiatr 2009;67:1133-1142.
Toyoshima Y, Yamada M, Onodera O, Shimohata M, Inenaga C, Fujita N, Morita M, Tsuji S, Takahashi H. SCA17 homozygote showing Huntington’s disease-like phenotype. Ann Neurol 2004;55:281-286.
Wahlström A, Hugonin L, Perálvarez-Marín A, Jarvet J, Gräslund A. Secondary structure conversions of Alzheimer's Abeta(1-40) peptide induced by membrane-mimicking detergents. FEBS J 2008;275:5117-5128.
Wang J, Gines S, MacDonald ME, Gusella JF. Reversal of a full-length mutant huntingtin neuronal cell phenotype by chemical inhibitors of polyglutamine-mediated aggregation. BMC Neurosci 2005;6:1.
Wullner U. Genes implicated in the pathogenesis of spinocerebellar ataxias. Drugs Today 2003;39:927-937.
Zhang X, Smith DL, Meriin AB, Engemann S, Russel DE, Roark M, Washington SL, Maxwell MM, Marsh JL, Thompson LM, Wanker EE, Young AB, Housman DE, Bates GP, Sherman MY, Kazantsev AG. A potent small molecule inhibits polyglutamine aggregation in Huntington's disease neurons and suppresses neurodegeneration in vivo. Proc Natl Acad Sci USA 2005;102:892-897.
Zhuchenko O, Bailey J, Bonnen P, Ashizawa T, Stockton DW, Amos C, Dobyns WB, Subramony SH, Zoghbi HY, Lee CC. Autosomal dominant cerebellar ataxia (SCA6) associated with small polyglutamine expansions in the alpha 1A-voltage-dependent calcium channel. Nat Genet 1997;15:62-69.
Zoghbi HY and Orr HT. Glutamine repeats and neurodegeneration. Annu Rev Neurosci 2000;23:217-247.