Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA.
Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA; Geriatric Research, Education and Clinical Center, Pittsburgh VA Healthcare System, Pittsburgh, PA, USA.
Neurobiol Dis. 2019 May;125:146-153. doi: 10.1016/j.nbd.2019.01.004. Epub 2019 Jan 15.
α-Synuclein plays a central role in the pathogenesis of Parkinson's disease (PD); interventions that decrease its expression appear neuroprotective in PD models. Successful translation of these observations into effective therapies will be dependent on the safety of suppressing α-synuclein expression in the adult brain. We investigated long-term α-synuclein knockdown in the adult rat CNS. 8-month old animals received either AAV-sh[Snca] (an RNA interference vector targeting the Snca mRNA transcript) or AAV-sh[Ctrl] (a control vector) unilaterally into the substantia nigra. No signs of systemic toxicity or motor dysfunction were observed in either experimental group over 12 months. Viral transgene expression persisted to 12 months post-inoculation, at which point Snca mRNA expression in substantia nigra dopaminergic neurons of animals that received AAV-sh[Snca] was decreased by ≈90%, and α-synuclein immunoreactivity by >70% relative to the control side. Stereological quantification of Nissl-labeled neurons showed no evidence of neurodegeneration in the substantia nigra 12 months after inoculation with either vector, and we observed abundant dopaminergic neurons with minimal α-synuclein immunoreactivity that appeared otherwise unremarkable in the AAV-sh[Snca] group. Despite the absence of neurodegeneration, some loss of TH expression was evident in nigral neurons after transduction with either vector, presumably a non-specific consequence of vector delivery, cellular transduction, or expression of shRNA or GFP. We conclude that long-term α-synuclein knockdown in the substantia nigra does not cause significant functional deficits in the ascending dopaminergic projection, or neurodegeneration. These findings are encouraging that it may be feasible to target α-synuclein expression therapeutically in PD.
α-突触核蛋白在帕金森病 (PD) 的发病机制中起着核心作用；降低其表达的干预措施在 PD 模型中显示出神经保护作用。将这些观察结果成功转化为有效的治疗方法将取决于在成年大脑中抑制 α-突触核蛋白表达的安全性。我们研究了成年大鼠中枢神经系统中 α-突触核蛋白的长期敲低。8 个月大的动物单侧接受 AAV-sh[Snca]（一种针对 Snca mRNA 转录本的 RNA 干扰载体）或 AAV-sh[Ctrl]（对照载体）。在 12 个月内，两个实验组均未观察到全身毒性或运动功能障碍的迹象。病毒转基因表达持续到接种后 12 个月，此时接受 AAV-sh[Snca]的动物纹状体多巴胺能神经元中的 Snca mRNA 表达降低了约 90%，α-突触核蛋白免疫反应性降低了 >70%相对对照侧。尼氏染色标记神经元的立体定量分析显示，接种任何一种载体 12 个月后，黑质中均没有神经退行性变的证据，我们观察到大量多巴胺能神经元，其 α-突触核蛋白免疫反应性降低 >70%，且在 AAV-sh[Snca]组中其他方面无明显异常。尽管没有神经退行性变，但在转导后，黑质神经元中的 TH 表达明显减少，这可能是载体递送、细胞转导或 shRNA 或 GFP 表达的非特异性后果。我们得出结论，黑质中 α-突触核蛋白的长期敲低不会导致上行多巴胺能投射的明显功能缺陷或神经退行性变。这些发现令人鼓舞，表明在 PD 中靶向 α-突触核蛋白表达进行治疗可能是可行的。
