Background: Spinocerebellar ataxia type 2 (SCA2) is an autosomal-dominant hereditary ataxia characterized by progressive gait and limb ataxia, dysarthria, slow saccades, neuropathy and dementia. The expansion of trinucleotide CAG repeats in the coding region of the ATXN-2 gene leads to expanded polyglutamine stretch in the mutated protein which causes neuronal death. Objective: In this study, we investigated the blood plasma of SCA2 patients to find protein biomarkers. Methods: Thirty-two ataxia patients clinically suspected for SCA2 were evaluated by the International Co-operative Ataxia Rating Scale followed by genetic analysis using PCR. Plasma proteomics of SCA2 patients and age- and gender-matched healthy controls was done using 2D-difference in-gel electrophoresis, LC-MS/MS and Western blot. Results: Genetic analysis confirmed 10 of 32 suspected SCA2 patients. Proteomic data revealed nine differentially expressed proteins in SCA2. These proteins find good association with oxidative stress, calcium-dependent apoptosis, neuropathy, and cognitive impairment in SCA2 patients. Interestingly, the elevated levels of the voltage-dependent calcium channel γ-3 subunit showed a direct correlation with calcium-generated apoptosis of Purkinje cells. The cognitive deficit, a common symptom in SCA2 patients, seems to correlate with decreased levels of transthyretin and retinol-binding protein-4. Conclusions: Some of these identified proteins in SCA2 can be useful for therapeutic, diagnostic and prognostic purposes.

Keywords:
2D-difference in-gel electrophoresis, Spinocerebellar ataxia, Proteomics, Neurological disorders
1.
Dueñas AM, Sánchez I, Juan MC, Dávalos A, Alvarez R, Latorre P: Cellular and molecular pathways triggering neurodegeneration in the spinocerebellar ataxias. Cerebellum 2010;9:148-166.
2.
Zoghbi HFY, Orr HT: Glutamine repeats and neurodegeneration. Annu Rev Neurosci 2000;23:217-247.
3.
Dueñas MA: The highly heterogeneous spinocerebellar ataxias: from genes to targets for therapeutic intervention. Cerebellum 2008;7:97-100.
4.
Orr HT: Cell biology of spinocerebellar ataxia. J Cell Biol 2012;197:167-177.
5.
Pulst SM, Nechiporuk A, Nechiporuk T, Gispert S, Chen XN, Lopes-Cendes I, Pearlman S, Starkman S, Orozco-Diaz G, Lunkes A, DeJong P, Rouleau GA, Auburger G, Korenberg JR, Figueroa C, Sahba S: Moderate expansion of a normally biallelic trinucleotide repeat in spinocerebellar ataxia type 2. Nat Genet 1996;14:269-276.
6.
Pulst SM, Santos N, Wang D, Yang H, Huynh D, Velazquez L: Spinocerebellar ataxia type 2:polyQ repeat variation in the CACNA1A calcium channel modifies age of onset. Brain 2005;128:2297-2303.
7.
Auburger GWJ: Spinocerebellar ataxia type 2. Handb Clin Neurol Ataxic Disorders Ed 2012;103:423-436.
8.
Bird TD: Hereditary ataxia overview. http://www.ncbi.nlm.nih.gov/books/NBK1138/ (modified July 2011).
9.
Basu P, Chattopadhyay B, Gangopadhaya PK, Mukherjee SC, Sinha KK, Das SK, Roychoudhury S, Majumder PP, Bhattacharyya NP: Analysis of CAG repeats in SCA1, SCA2, SCA3, SCA6, SCA7 and DRPLA loci in spinocerebellar ataxia patients and distribution of CAG repeats at the SCA1, SCA2 and SCA6 loci in nine ethnic populations of eastern India. Hum Genet 2000;106:597-604.
10.
Sinha KK, Worth PF, Jha DK, Sinha S, Stinton VJ, Davis MB, Wood NW, Sweeney MG, Bhatia KP: Autosomal dominant cerebellar ataxia: SCA2 is the most frequent mutation in eastern India. J Neurol Neurosurg Psychiatry 2004;75:448-452.
11.
Faruq M, Scaria V, Singh I, Tyagi S, Srivastava AK, Mukerji M: SCA-LSVD: a repeat-oriented locus-specific variation database for genotype to phenotype correlations in spinocerebellar ataxias. Hum Mut 2009;30:1037-1042.
12.
Netravathi M, Pal PK, Purushottam M, Thennarasu K, Mukherjee M, Jain S: Spinocerebellar ataxias types 1, 2 and 3: age adjusted clinical severity of disease at presentation correlates with size of CAG repeat lengths. J Neurol Sci 2009;277:83-86.
13.
Kasumu A, Bezprozvanny I: Deranged calcium signaling in Purkinje cells and pathogenesis in spinocerebellar ataxia 2 (SCA2) and other ataxias. Cerebellum 2012;11:630-639.
14.
Laffita-Mesa JM, Bauer PO, Kourí V, Peña Serrano L, Roskams J, Almaguer Gotay D, Montes Brown JC, Martínez Rodríguez PA, González-Zaldívar Y, Almaguer Mederos L, Cuello-Almarales D, Aguiar Santiago J: Epigenetics DNA methylation in the core ataxin-2 gene promoter: novel physiological and pathological implications. Hum Genet 2012;131:625-638.
15.
Trouillas P, Takayanagi T, Hallett M, Currier RD, Subramony SH, Wessel K, Bryer A, Diener HC, Massaquoi S, Gomez CM, Coutinho P, Ben Hamida M, Campanella G, Filla A, Schut L, Timann D, Honnorat J, Nighoghossian N, Manyam B: International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome. The Ataxia Neuropharmacology Committee of the World Federation of Neurology. J Neurol Sci 1997;145:205-211.
16.
Swarup V, Srivastava AK, Padma MV, Rajeswari MR: Quantification of circulating plasma DNA in Friedreich's ataxia and spinocerebellar ataxia types 2 and 12. DNA Cell Biol 2011;30:389-394.
17.
Swarup V, Srivastava AK, Rajeswari MR: Identification and quantification of differentially expressed proteins in plasma of spinocerebellar ataxia type 12. Neurosci Res 2012;73:161-167.
18.
Storey E, Tuck K, Hester R, Hughes A, Churchyard A: Inter-rater reliability of the International Cooperative Ataxia Rating Scale (ICARS). Mov Disord 2004;19:190-192.
19.
Saleem Q, Choudhry S, Mukerji M, Bashyam L, Padma MV, Chakravarthy A: Molecular analysis of autosomal dominant hereditary ataxias in the Indian population: high frequency of SCA2 and evidence for a common founder mutation. Hum Genet 2000;106:179-187.
20.
Freeman WM, Hemby SE: Proteomics for protein expression profiling in neuroscience. Neurochem Res 2004;29:1065-1081.
21.
Varadi G, Strobeck M, Koch S, Caglioti L, Zucchi C, Palyi G: Molecular elements of ion permeation and selectivity within calcium channels. Crit Rev Biochem Mol Biol 1999;34:181-214.
22.
Chu PJ, Robertson HM, Best PM: Calcium channel gamma subunits provide insights into the evolution of this gene family. Gene 2001;280:37-48.
23.
Singer D, Biel M, Lotan I, Flockerzi V, Hofmann F, Dascal N: The roles of the subunits in the function of the calcium channel. Science 1991;253:1553-1557.
24.
Liu J, Tang TS, Tu H, Nelson O, Herndon E, Huynh DP, Pulst SM, Bezprozvanny I: Deranged calcium signalling and neurodegeneration in spinocerebellar ataxia type 2. J Neurosci 2009;29:9148-9162.
25.
Bezprozvanny I: Role of inositol 1,4,5-trisphosphate receptors in pathogenesis of Huntington's disease and spinocerebellar ataxias. Neurochem Res 2011;36:1186-1197.
26.
Cocco S, Diaz G, Stancampiano R, Diana A, Carta M, Curreli R, Sarais L, Fadda F: Vitamin A deficiency produces spatial learning and memory impairment in rats. Neuroscience 2002;115:475-482.
27.
Etchamendy N, Enderlin V, Marighetto A, Pallet V, Higueret P, Jaffard R: Vitamin A deficiency and relational memory deficit in adult mice: relationships with changes in brain retinoid signalling. Behav Brain Res 2003;145:37-49.
28.
Yadav R, Pal PK, Krishna N, Amar BR, Jain S, Purushottam M: Electrophysiological evaluation of spinocerebellar ataxias 1, 2 and 3. J Neurol Sci 2012;312:142-145.
29.
Ng DS, O'Connor PW, Mortimer CB, Leiter LA, Connelly PW, Hegele RA: Case report: retinopathy and neuropathy associated with complete apolipoprotein A-I deficiency. Am J Med Sci 1996;312:30-33.
30.
Roche M, Rondeau P, Singh NR, Tarnus E, Bourdon E: The antioxidant properties of serum albumin. FEBS Lett 2008;582:1783-1787.
31.
Candiano G, Petretto A, Bruschi M, Santucci L, Dimuccio V, Prunotto M, Gusmano R, Urbani A, Ghiggeri GM: The oxido-redox potential of albumin methodological approach and relevance to human diseases. J Proteomics 2009;73:188-195.
32.
Forment GR, Bonne OM, Gutiérrez RG, Blanco AP, Balboa JP, Pereira N, Perez LV: Oxidative damage and antioxidant enzymes in blood of patients with spinocerebellar ataxia type 2. Rev Cubana Genet Comun 2010;4:42-47.
33.
Takeda S, Sato N, Rakugi H, Morishita R: Plasma beta-amyloid as potential biomarker of Alzheimer disease: possibility of diagnostic tool for Alzheimer disease. Mol Biosyst 2010;6:1760-1766.
34.
Mates JM, Pérez-Gómez C, Nuñez de Castro I: Antioxidant enzymes and human diseases. Clin Biochem 1999;32:595-603.
35.
Jackson RL, Baker HN, Gilliam EB, Gotto AM: Primary structure of very low density apolipoprotein C-II of human plasma. Proc Natl Acad Sci USA 1977;74:1942-1945.
36.
Mendivil CO, Zheng C, Furtado J, Lel J, Sacks FM: Metabolism of VLDL and LDL containing apolipoprotein C-III and not other small apolipoproteins - R2. Arterioscler Thromb Vasc Biol 2009;30:239-245.
37.
Turnbull VJ, Storey E, Tarlac V, Walsh R, Stefani D, Clark R: Different ataxin-2 antibodies display different immunoreactive profiles. Brain Res 2004;1027:103-116.
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