From the Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany, the Center for Nanoscale Microscopy and Molecular Physiology of the Brain, D-37073 Göttingen, Germany.
the Tanz Centre for Research in Neurodegenerative Diseases and Department of Medical Biophysics, University of Toronto, Ontario M5T 2S8, Canada, and.
J Biol Chem. 2014 Nov 7;289(45):31224-40. doi: 10.1074/jbc.M114.559237. Epub 2014 Sep 17.
Parkinson disease is associated with the progressive loss of dopaminergic neurons from the substantia nigra. The pathological hallmark of the disease is the accumulation of intracytoplasmic inclusions known as Lewy bodies that consist mainly of post-translationally modified forms of α-synuclein. Whereas phosphorylation is one of the major modifications of α-synuclein in Lewy bodies, sumoylation has recently been described. The interplay between α-synuclein phosphorylation and sumoylation is poorly understood. Here, we examined the interplay between these modifications as well as their impact on cell growth and inclusion formation in yeast. We found that α-synuclein is sumoylated in vivo at the same sites in yeast as in human cells. Impaired sumoylation resulted in reduced yeast growth combined with an increased number of cells with inclusions, suggesting that this modification plays a protective role. In addition, inhibition of sumoylation prevented autophagy-mediated aggregate clearance. A defect in α-synuclein sumoylation could be suppressed by serine 129 phosphorylation by the human G protein-coupled receptor kinase 5 (GRK5) in yeast. Phosphorylation reduced foci formation, alleviated yeast growth inhibition, and partially rescued autophagic α-synuclein degradation along with the promotion of proteasomal degradation, resulting in aggregate clearance in the absence of a small ubiquitin-like modifier. These findings suggest a complex interplay between sumoylation and phosphorylation in α-synuclein aggregate clearance, which may open new horizons for the development of therapeutic strategies for Parkinson disease.
帕金森病与黑质多巴胺能神经元的进行性丧失有关。该疾病的病理标志是细胞内包含物的积累，这些包含物被称为路易体，主要由α-突触核蛋白的翻译后修饰形式组成。虽然磷酸化是路易体中α-突触核蛋白的主要修饰之一，但最近已描述了 sumoylation。α-突触核蛋白磷酸化和 sumoylation 之间的相互作用知之甚少。在这里，我们研究了这些修饰之间的相互作用以及它们对酵母中细胞生长和包含物形成的影响。我们发现，α-突触核蛋白在酵母体内与在人类细胞中一样，在体内发生 sumoylation。sumoylation 受损导致酵母生长减少，同时具有包含物的细胞数量增加，这表明该修饰发挥了保护作用。此外，抑制 sumoylation 会阻止自噬介导的聚集体清除。在酵母中，人类 G 蛋白偶联受体激酶 5（GRK5）可以通过丝氨酸 129 磷酸化来抑制α-突触核蛋白的 sumoylation。磷酸化减少焦点形成，缓解酵母生长抑制，并部分挽救自噬性α-突触核蛋白降解，同时促进蛋白酶体降解，从而在没有小泛素样修饰物的情况下清除聚集体。这些发现表明 sumoylation 和 phosphorylation 在α-突触核蛋白聚集体清除中存在复杂的相互作用，这可能为帕金森病的治疗策略的发展开辟新的视野。
