Gorbatyuk Oleg S, Li Shoudong, Sullivan Layla F, Chen Weijun, Kondrikova Galina, Manfredsson Fredric P, Mandel Ronald J, Muzyczka Nicholas
Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610, USA.
Proc Natl Acad Sci U S A. 2008 Jan 15;105(2):763-8. doi: 10.1073/pnas.0711053105. Epub 2008 Jan 4.
Studies have shown that alpha-synuclein (alpha-syn) deposited in Lewy bodies in brain tissue from patients with Parkinson disease (PD) is extensively phosphorylated at Ser-129. We used recombinant Adeno-associated virus (rAAV) to overexpress human wild-type (wt) alpha-syn and two human alpha-syn mutants with site-directed replacement of Ser-129 to alanine (S129A) or to aspartate (S129D) in the nigrostriatal tract of the rat to investigate the effect of Ser-129 phosphorylation state on dopaminergic neuron pathology. Rats were injected with rAAV2/5 vectors in the substantia nigra pars compacta (SNc) on one side of the brain; the other side remained as a nontransduced control. The level of human wt or mutant alpha-syn expressed on the injected side was about four times the endogenous rat alpha-syn. There was a significant reduction of dopaminergic neurons in the SNc and dopamine (DA) and tyrosine hydroxylase (TH) levels in the striatum of all S129A-treated rats as early as 4 wk postinjection. Nigral DA pathology occurred more slowly in the wt-injected animals, but by 26 wk the wt alpha-syn group lost nigral TH neurons equivalent to the mutated S129A group at 8 wk. In stark contrast, we did not observe any pathological changes in S129D-treated animals. Therefore, the nonphosphorylated form of S129 exacerbates alpha-syn-induced nigral pathology, whereas Ser-129 phosphorylation eliminates alpha-syn-induced nigrostriatal degeneration. This suggests possible new therapeutic targets for Parkinson Disease.
研究表明，帕金森病（PD）患者脑组织中路易小体里沉积的α-突触核蛋白（α-syn）在丝氨酸129位点发生了广泛磷酸化。我们利用重组腺相关病毒（rAAV）在大鼠黑质纹状体通路中过表达人野生型（wt）α-syn以及丝氨酸129定点突变为丙氨酸（S129A）或天冬氨酸（S129D）的两个人α-syn突变体，以研究丝氨酸129磷酸化状态对多巴胺能神经元病理变化的影响。在大鼠一侧脑的黑质致密部（SNc）注射rAAV2/5载体；另一侧作为未转导的对照。注射侧表达的人wt或突变体α-syn水平约为大鼠内源性α-syn的四倍。早在注射后4周，所有接受S129A处理的大鼠的SNc中多巴胺能神经元以及纹状体中多巴胺（DA）和酪氨酸羟化酶（TH）水平就显著降低。wt注射组动物的黑质DA病理变化出现得较慢，但到26周时，wt α-syn组损失的黑质TH神经元数量与8周时的突变S129A组相当。与之形成鲜明对比的是，我们在接受S129D处理的动物中未观察到任何病理变化。因此，S129的非磷酸化形式会加剧α-syn诱导的黑质病理变化，而丝氨酸129磷酸化则可消除α-syn诱导的黑质纹状体变性。这提示了帕金森病可能的新治疗靶点。
