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. 2011 Apr 30;43(4):216-22.
doi: 10.3858/emm.2011.43.4.026.

Dopamine promotes formation and secretion of non-fibrillar alpha-synuclein oligomers

He-Jin Lee  1 , Sung Min Baek, Dong-Hwan Ho, Ji-Eun Suk, Eun-Duk Cho, Seung-Jae Lee
Affiliations

Dopamine promotes formation and secretion of non-fibrillar alpha-synuclein oligomers

He-Jin Lee et al. Exp Mol Med. .

Abstract

Parkinson's disease (PD) is characterized by selective and progressive degeneration of dopamine (DA)-producing neurons in the substantia nigra pars compacta (SNpc) and by abnormal aggregation of α-synuclein. Previous studies have suggested that DA can interact with α-synuclein, thus modulating the aggregation process of this protein; this interaction may account for the selective vulnerability of DA neurons in patients with PD. However, the relationship between DA and α-synuclein, and the role in progressive degeneration of DA neurons remains elusive. We have shown that in the presence of DA, recombinant human α-synuclein produces non-fibrillar, SDS-resistant oligomers, while β-sheet-rich fibril formation is inhibited. Pharmacologic elevation of the cytoplasmic DA level increased the formation of SDS-resistant oligomers in DA-producing neuronal cells. DA promoted α-synuclein oligomerization in intracellular vesicles, but not in the cytosol. Furthermore, elevation of DA levels increased secretion of α-synuclein oligomers to the extracellular space, but the secretion of monomers was not changed. DA-induced secretion of α-synuclein oligomers may contribute to the progressive loss of the dopaminergic neuronal population and the pronounced neuroinflammation observed in the SNpc in patients with PD.

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Figures

Figure 1
Figure 1
DA-induced oligomerization of α-synuclein in vitro. (A) Thioflavin T binding assay. Recombinant α-synuclein was incubated in the presence (red) or absence (green) of DA. (B) CD analysis of α-synuclein monomer (blue), fibrils (green), and oligomer-monomer mixture prepared in the presence of DA (red).
Figure 2
Figure 2
Analysis of DA-induced α-synuclein oligomers Size exclusion chromatography (A) and Western blotting (B) of α-synuclein proteins incubated with DA. (Dotted line: α-synuclein monomer, black line: DA-induced α-synuclein oligomer profiles. △: blue-dextran [2,000 kDa], █: albumin [66,000 Da], ●: cytochrome c [12,400 Da]) (C) Electron microscopy images of control (left) and DA-induced oligomers (right) (Scale bar: 0.2 µm).
Figure 3
Figure 3
DA-induced α-synuclein aggregation and vesicular localization in SH-SY5Y cells. (A) L-dopa treatment increased α-synuclein aggregation in differentiated SH-SY5Y cells in a dose-dependent manner. Differentiated SH-SY5Y neuronal cells overexpressing α-synuclein were treated with L-dopa at final concentrations of 0, 50, 150, and 400 µM for 48 hours. (B) Inhibition of MAO-B by pargyline (0, 1, 5, and 20 µM) further elevated α-synuclein aggregate formation in L-dopa-treated cells (1 mM). The data were obtained from the same blot. (C) Addition of c-dopa (1, 4, and 10 mM) inhibited DA-induced α-synuclein aggregation (L-dopa [1 mM)], pargyline [5 µM]). All the data shown here were originated from the same blot. (D) Quantitation of high MW α-synuclein aggregates in blot (C). β-actin was shown to demonstrate equal loading of proteins on all blots.
Figure 4
Figure 4
Localization of DA-induced α-synuclein aggregates in vesicle fractions. Differentiated SH-SY5Y neuronal cells overexpressing α-synuclein were treated with 1 mM L-dopa and the extract was separated by density gradient centrifugation to obtain vesicle (Ves) or cytosolic (Cyt) fractions. Note the increased α-synuclein aggregates (side bar) in vesicle fraction of L-dopa treated cells.
Figure 5
Figure 5
DA-induced secretion of α-synuclein aggregates from SH-SY5Y cells. Differentiated SH-SY5Y cells were treated with 1 mM L-dopa and 10 µM pargyline for indicated times and the conditioned media were collected and analyzed for α-synuclein release. Note that the monomer levels do not differ but the amount of α-synuclein aggregates increased significantly in L-dopa- and pargyline-treated cells (***P < 0.001).
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References

    1. Bisaglia M, Mammi S, Bubacco L. Kinetic and structural analysis of the early oxidation products of dopamine: analysis of the interactions with {alpha}- synuclein. J Biol Chem. 2007;282:15597–15605. - PubMed
    1. Braak H, Del Tredici K, Rub U, de Vos RA, Jansen Steur EN, Braak E. Staging of brain pathology related to sporadic Parkinson's disease. Neurobiol Aging. 2003;24:197–211. - PubMed
    1. Burke WJ, Kumar VB, Pandey N, Panneton WM, Gan Q, Franko MW, O'Dell M, Li SW, Pan Y, Chung HD, Galvin JE. Aggregation of alpha-synuclein by DOPAL, the monoamine oxidase metabolite of dopamine. Acta Neuropathol. 2008;115:193–203. - PubMed
    1. Cappai R, Leck SL, Tew DJ, Williamson NA, Smith DP, Galatis D, Sharples RA, Curtain CC, Ali FE, Cherny RA, Culvenor JG, Bottomley SP, Masters CL, Barnham KJ, Hill AF. Dopamine promotes alpha-synuclein aggregation into SDS-resistant soluble oligomers via a distinct folding pathway. FASEB J. 2005;19:1377–1379. - PubMed
    1. Conway KA, Rochet JC, Bieganski RM, Lansbury PT., Jr Kinetic stabilization of the alpha-synuclein protofibril by a dopamine-alpha-synuclein adduct. Science. 2001;294:1346–1349. - PubMed

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