Investigation of alpha-synuclein pathogenic mechanisms with human stem cells and neurons

帕金森病（PD）是一种进行性脑退行性疾病。环境和遗传因素的混合物被认为是导致这种情况的散发形式。所有PD病例之间的一个共同联系是一种称为α-突触核蛋白的蛋白质的不寻常和破坏性行为。这种蛋白质存在于所有人的神经元中，通常是良性的。然而，在帕金森氏症和某些形式的痴呆症患者中，α-突触核蛋白呈现出不寻常的形状，并对神经元产生毒性，最终杀死它们。这种蛋白质的第二个令人不快的特性是，它被认为是通过大脑传播疾病。这种行为可能类似于感染牛肉的朊病毒蛋白如何从肠道神经元扩散到脊髓，最终进入大脑，导致严重的神经系统问题。我们建议在实验室中使用活的人类神经元来模拟α-突触核蛋白的致病行为。我们最近发表了来自一名患者的诱导多能干细胞（iPSC），该患者具有4个编码α-突触核蛋白的基因拷贝，而不是正常的两个拷贝。这位患者和她的家庭中大约一半的成员患有严重的早发性PD伴痴呆症。由PD iPSC制成的神经元产生的α-突触核蛋白是来自该患者未受影响的一级亲属的对照神经元的两倍。PD和健康神经元将用于比较研究，以研究由α-突触核蛋白过度产生引起的任何问题。在平行工作中，人类胚胎干细胞（hESC）被遗传修饰，以超过正常水平2倍至6倍的广泛范围过度产生α-突触核蛋白。iPSC和hESC都将用于研究α-突触核蛋白的异常行为，包括其神经毒性特性。如果观察到可重复的致病行为，这些细胞将是建模PD和了解α-突触核蛋白如何杀死神经元的理想选择。该系统将用于筛选可以阻止α-突触核蛋白有害行为的药物。将对选定数量的化合物进行几次试点筛选，以确定这种方法的可行性。预防α-突触核蛋白的错误折叠和病理行为的有效药物将通过停止或严重延缓疾病的进展来改变PD和痴呆治疗的面貌。

Parkinson's disease (PD) is a progressive degenerative disorder of the brain. A mixture of environmental and genetic triggers are thought to cause the sporadic forms of this condition. A common link between all cases of PD is the unusual and damaging behaviour of a protein known as alpha-synuclein. This protein is present in neurons of all people, and is usually benign. However, in people with Parkinson's and some forms of dementia, alpha-synuclein takes on unusual shapes and becomes toxic to neurons, eventually killing them. A second unpleasant property of this protein is that it is thought to travel through the brain spreading disease. This behaviour may be similar to how prion protein from infected beef can spread from gut neurons into the spinal cord, and eventually into the brain causing severe neurological problems. We propose to use live human neurons to model the disease-causing behaviour of alpha-synuclein in the laboratory. We have recently published induced pluripotent stem cells (iPSCs) from a patient with 4 copies of the gene encoding alpha-synuclein, instead of the normal two copies. This patient and about half the members of her family get a severe, early-onset form of PD with dementia. The neurons made from PD iPSCs produce twice as much alpha-synuclein protein as control neurons from an unaffected 1st-degree relative of this patient. The PD and healthy neurons will be used in comparative studies to investigate any problems caused by over-production of alpha-synuclein. In parallel work, human embryonic stem cells (hESCs) were genetically modified to over-produce alpha-synuclein at a wide range from 2-fold to 6-fold above normal levels. Both iPSCs and hESCs will be used to investigate the unusual behaviour of alpha-synuclein including its neurotoxic properties. If reproducible, disease-causing behaviour is observed, these cells will be ideal for modeling PD and understanding how alpha-synuclein kills neurons. This system will be used for screening drugs that could stop the harmful behaviour of alpha-synuclein. Several pilot screens of a select number of compounds will be performed to determine the feasibility of this approach. Potent drugs that prevent the misfolding and pathological behaviour of alpha-synuclein will change the face of PD and dementia treatment by stopping or severely retarding the progression of the disease.