Monti Barbara, Polazzi Elisabetta, Batti Laura, Crochemore Christophe, Virgili Marco, Contestabile Antonio
Department of Biology, University of Bologna, Bologna, Italy.
J Neurochem. 2007 Oct;103(2):518-30. doi: 10.1111/j.1471-4159.2007.04778.x. Epub 2007 Jul 17.
The physiological role of alpha-synuclein, a protein found enriched in intraneuronal deposits characterizing Parkinson's disease, is debated. While its aggregation is usually considered linked to neuropathology, its normal function may be related to fundamental processes of synaptic transmission and plasticity. By using antisense oligonucleotide strategy, we report in this study that alpha-synuclein silencing in cultured cerebellar granule cells results in widespread death of these neurons, thus demonstrating an essential pro-survival role of the protein towards primary neurons. To study alpha-synuclein expression and processing in a Parkinson's disease model of neurotoxicity, we exposed differentiated cultures of cerebellar granule neurons to toxic concentrations of 6-hydroxydopamine (6-OHDA). This resulted in neuronal death accompanied by a decrease of the monomeric form of alpha-synuclein, which was due to both decreased synthesis of the protein and its increased mono-ubiquitination accompanied by nuclear translocation. The essential neuroprotective role of alpha-synuclein was confirmed by the fact that subchronic valproate treatment, which increases alpha-synuclein expression and prevents its nuclear translocation in cerebellar granule cells exposed to 6-OHDA, significantly protected these neurons from 6-OHDA insult. In agreement with the pro-survival role of alpha-synuclein in this model, subtoxic concentrations of alpha-synuclein antisense oligonucleotides, aggravated 6-OHDA toxicity towards granule neurons. Our results demonstrate that normal alpha-synuclein expression is essential for the viability of primary neurons and that its pro-survival role is abolished in 6-OHDA neurotoxic challenge. These results are relevant to more precisely define the role of alpha-synuclein in neuronal cells and to better understand its putative involvement in neurodegeneration.
α-突触核蛋白是一种在帕金森病特征性神经元内沉积物中大量存在的蛋白质，其生理作用存在争议。虽然通常认为其聚集与神经病理学有关，但其正常功能可能与突触传递和可塑性的基本过程有关。通过使用反义寡核苷酸策略，我们在本研究中报告，培养的小脑颗粒细胞中α-突触核蛋白沉默导致这些神经元广泛死亡，从而证明该蛋白对原代神经元具有重要的促存活作用。为了研究α-突触核蛋白在神经毒性帕金森病模型中的表达和加工，我们将分化的小脑颗粒神经元培养物暴露于有毒浓度的6-羟基多巴胺（6-OHDA）。这导致神经元死亡，同时α-突触核蛋白的单体形式减少，这是由于该蛋白合成减少及其单泛素化增加并伴有核转位。α-突触核蛋白的重要神经保护作用通过以下事实得到证实：亚慢性丙戊酸盐治疗增加α-突触核蛋白表达并防止其在暴露于6-OHDA的小脑颗粒细胞中的核转位，显著保护这些神经元免受6-OHDA损伤。与该模型中α-突触核蛋白的促存活作用一致，亚毒性浓度的α-突触核蛋白反义寡核苷酸加重了6-OHDA对颗粒神经元的毒性。我们的结果表明，正常的α-突触核蛋白表达对原代神经元的存活至关重要，并且其促存活作用在6-OHDA神经毒性挑战中被消除。这些结果对于更精确地定义α-突触核蛋白在神经元细胞中的作用以及更好地理解其在神经退行性变中的假定参与具有重要意义。
