Proteomic and quantitative data of dopaminergic neuron vesicles potentiated by beta-synuclein after MPTP-induced toxicity

Previous studies have demonstrated the importance of alpha-synuclein as a modulator of various mechanisms implicated in chemical neurotransmission but information about other two synuclein family members’ involvement in molecular processes taking place in presynaptic terminals is limited. Here we demonstrated that dopamine uptake by synaptic vesicles isolated from the striatum of mice lacking beta-synuclein was significantly reduced. Reciprocally, reintroduction, either in vivo or in vitro, of beta-synuclein but not alpha- or gamma-synuclein improved uptake by vesicles isolated from the striatum of triple-alpha/beta/gamma-synuclein deficient mice. Proteomic analysis of synuclein-free and beta-synuclein-only-containing synaptic vesicles suggested that mechanistically, beta-synuclein potentiates vesicular monoamine transporter 2 (VMAT2)-dependent dopamine uptake by assembling specific multiprotein complexes comprised of resident vesicular proteins and transiently associated predominantly cytosolic proteins. The increased availability of such complexes on the surface of striatal synaptic vesicles lacking other synucleins should also promote sequestration of 1-methyl-4-phenylpyridinium (MPP+), a toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which explains the resistance of dopaminergic neurons of substantia nigra lacking alpha-synuclein and/or gamma-synuclein to this neurotoxin.

The present data demonstrate the rational distribution of the most significantly altered proteins between WT, TKO, and alpha/gamma-synuclein KO striatal vesicle proteomes. Data cover essential information regarding proteomic assay.

既往研究已证实α-突触核蛋白作为化学神经递质传递相关机制调节因子的重要性，然而，关于其他两种突触核蛋白家族成员在突触前末端发生的分子过程中的参与情况的信息则相对有限。本研究中，我们证明了从缺乏β-突触核蛋白的小鼠纹状体中分离的突触小泡对多巴胺的摄取显著降低。相反，无论是在体内还是在体外重新引入β-突触核蛋白（而非α-或γ-突触核蛋白），都改善了从三重α/β/γ-突触核蛋白缺乏小鼠纹状体中分离的小泡的摄取。对无突触核蛋白和小泡中仅含β-突触核蛋白的突触小泡进行的蛋白质组学分析表明，从机制上讲，β-突触核蛋白通过组装由驻留小泡蛋白和短暂结合的以细胞质蛋白为主的特定多蛋白复合物，增强了依赖小泡单胺转运蛋白2（VMAT2）的多巴胺摄取。这些复合物在缺乏其他突触核蛋白的纹状体小泡表面的增加可用性也应促进1-甲基-4-苯基吡啶（MPP+），即1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）的毒性代谢产物，这解释了缺乏α-突触核蛋白和/或γ-突触核蛋白的黑质多巴胺能神经元对这种神经毒素的抵抗力。当前数据展示了野生型（WT）、敲除型（TKO）和α/γ-突触核蛋白敲除型纹状体小泡蛋白质组中最为显著改变蛋白的合理分布。数据涵盖了有关蛋白质组学检测的必要信息。