Ettle Benjamin, Kerman Bilal E, Valera Elvira, Gillmann Clarissa, Schlachetzki Johannes C M, Reiprich Simone, Büttner Christian, Ekici Arif B, Reis André, Wegner Michael, Bäuerle Tobias, Riemenschneider Markus J, Masliah Eliezer, Gage Fred H, Winkler Jürgen
Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schwabachanlage 6, 91054, Erlangen, Germany.
Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA.
Acta Neuropathol. 2016 Jul;132(1):59-75. doi: 10.1007/s00401-016-1572-y. Epub 2016 Apr 8.
Multiple system atrophy (MSA) is a rare atypical parkinsonian disorder characterized by a rapidly progressing clinical course and at present without any efficient therapy. Neuropathologically, myelin loss and neurodegeneration are associated with α-synuclein accumulation in oligodendrocytes, but underlying pathomechanisms are poorly understood. Here, we analyzed the impact of oligodendrocytic α-synuclein on the formation of myelin sheaths to define a potential interventional target for MSA. Post-mortem analyses of MSA patients and controls were performed to quantify myelin and oligodendrocyte numbers. As pre-clinical models, we used transgenic MSA mice, a myelinating stem cell-derived oligodendrocyte-neuron co-culture, and primary oligodendrocytes to determine functional consequences of oligodendrocytic α-synuclein overexpression on myelination. We detected myelin loss accompanied by preserved or even increased numbers of oligodendrocytes in post-mortem MSA brains or transgenic mouse forebrains, respectively, indicating an oligodendrocytic dysfunction in myelin formation. Corroborating this observation, overexpression of α-synuclein in primary and stem cell-derived oligodendrocytes severely impaired myelin formation, defining a novel α-synuclein-linked pathomechanism in MSA. We used the pro-myelinating activity of the muscarinic acetylcholine receptor antagonist benztropine to analyze the reversibility of the myelination deficit. Transcriptome profiling of primary pre-myelinating oligodendrocytes demonstrated that benztropine readjusts myelination-related processes such as cholesterol and membrane biogenesis, being compromised by oligodendrocytic α-synuclein. Additionally, benztropine restored the α-synuclein-induced myelination deficit of stem cell-derived oligodendrocytes. Strikingly, benztropine also ameliorated the myelin deficit in transgenic MSA mice, resulting in a prevention of neuronal cell loss. In conclusion, this study defines the α-synuclein-induced myelination deficit as a novel and crucial pathomechanism in MSA. Importantly, the reversible nature of this oligodendrocytic dysfunction opens a novel avenue for an intervention in MSA.
多系统萎缩（MSA）是一种罕见的非典型帕金森综合征，临床病程进展迅速，目前尚无有效治疗方法。在神经病理学上，髓鞘脱失和神经退行性变与少突胶质细胞中α-突触核蛋白的积累有关，但潜在的发病机制尚不清楚。在此，我们分析了少突胶质细胞α-突触核蛋白对髓鞘形成的影响，以确定MSA的潜在干预靶点。对MSA患者和对照进行尸检分析，以量化髓鞘和少突胶质细胞数量。作为临床前模型，我们使用转基因MSA小鼠、一种由髓鞘形成干细胞衍生的少突胶质细胞-神经元共培养体系以及原代少突胶质细胞，来确定少突胶质细胞α-突触核蛋白过表达对髓鞘形成的功能影响。我们分别在MSA患者尸检脑或转基因小鼠前脑中检测到髓鞘脱失，同时少突胶质细胞数量保持不变甚至增加，这表明在髓鞘形成过程中存在少突胶质细胞功能障碍。进一步证实这一观察结果的是，原代和干细胞衍生的少突胶质细胞中α-突触核蛋白的过表达严重损害了髓鞘形成，这确定了MSA中一种新的α-突触核蛋白相关发病机制。我们利用毒蕈碱型乙酰胆碱受体拮抗剂苯海索的促髓鞘形成活性，分析髓鞘形成缺陷的可逆性。对原代前髓鞘形成少突胶质细胞的转录组分析表明，苯海索可重新调整与髓鞘形成相关的过程，如胆固醇和膜生物合成，这些过程因少突胶质细胞α-突触核蛋白而受损。此外，苯海索恢复了干细胞衍生的少突胶质细胞中α-突触核蛋白诱导的髓鞘形成缺陷。令人惊讶的是，苯海索还改善了转基因MSA小鼠的髓鞘缺陷，从而防止了神经元细胞丢失。总之，本研究将α-突触核蛋白诱导的髓鞘形成缺陷定义为MSA中一种新的关键发病机制。重要的是，这种少突胶质细胞功能障碍的可逆性为MSA的干预开辟了一条新途径。
