Corti Olga, Hampe Cornelia, Koutnikova Hana, Darios Frédéric, Jacquier Sandrine, Prigent Annick, Robinson Jean-Charles, Pradier Laurent, Ruberg Merle, Mirande Marc, Hirsch Etienne, Rooney Thomas, Fournier Alain, Brice Alexis
INSERM U289, Hôpital de la Salpêtrière, Bâtiment Pharmacie, 47 boulevard de l'Hôpital, 75651 Paris Cedex 13, France.
Hum Mol Genet. 2003 Jun 15;12(12):1427-37. doi: 10.1093/hmg/ddg159.
Parkinson's disease (PD) is a severe neurological disorder, characterized by the progressive degeneration of the dopaminergic nigrostriatal pathway and the presence of Lewy bodies (LBs). The discovery of genes responsible for familial forms of the disease has provided insights into its pathogenesis. Mutations in the parkin gene, which encodes an E3 ubiquitin-protein ligase involved in the ubiquitylation and proteasomal degradation of specific protein substrates, have been found in nearly 50% of patients with autosomal-recessive early-onset parkinsonism. The abnormal accumulation of substrates due to loss of Parkin function may be the cause of neurodegeneration in parkin-related parkinsonism. Here, we demonstrate that Parkin interacts with, ubiquitylates and promotes the degradation of p38, a key structural component of the mammalian aminoacyl-tRNA synthetase complex. We found that the ubiquitylation of p38 is abrogated by truncated variants of Parkin lacking essential functional domains, but not by the pathogenic Lys161Asn point mutant. Expression of p38 in COS7 cells resulted in the formation of aggresome-like inclusions in which Parkin was systematically sequestered. In the human dopaminergic neuroblastoma-derived SH-SY5Y cell line, Parkin promoted the formation of ubiquitylated p38-positive inclusions. Moreover, the overexpression of p38 in SH-SY5Y cells caused significant cell death against which Parkin provided protection. Analysis of p38 expression in the human adult midbrain revealed strong immunoreactivity in normal dopaminergic neurons and the labeling of LBs in idiopathic PD. This suggests that p38 plays a role in the pathogenesis of PD, opening the way for a detailed examination of its potential non-canonical role in neurodegeneration.
帕金森病(PD)是一种严重的神经疾病,其特征是多巴胺能黑质纹状体通路进行性退化以及存在路易小体(LBs)。对家族性帕金森病相关基因的发现为其发病机制提供了线索。在近50%的常染色体隐性早发性帕金森综合征患者中发现了parkin基因的突变,该基因编码一种E3泛素蛋白连接酶,参与特定蛋白质底物的泛素化和蛋白酶体降解。由于Parkin功能丧失导致的底物异常积累可能是parkin相关帕金森综合征神经退行性变的原因。在此,我们证明Parkin与哺乳动物氨酰-tRNA合成酶复合体的关键结构成分p38相互作用、使其泛素化并促进其降解。我们发现,缺乏必需功能域的Parkin截短变体可消除p38的泛素化,但致病性赖氨酸161天冬酰胺点突变体则不能。p38在COS7细胞中的表达导致形成聚集体样包涵体,Parkin被系统性地隔离在其中。在人多巴胺能神经母细胞瘤衍生的SH-SY5Y细胞系中,Parkin促进了泛素化p38阳性包涵体的形成。此外,p38在SH-SY5Y细胞中的过表达导致显著的细胞死亡,而Parkin可提供保护作用。对成人中脑p38表达的分析显示,在正常多巴胺能神经元中有强烈的免疫反应性,在特发性帕金森病中有路易小体的标记。这表明p38在帕金森病的发病机制中起作用,为详细研究其在神经退行性变中潜在的非经典作用开辟了道路。