富含亮氨酸的重复激酶2(LRRK2)中的多个错义突变与家族形式的迟发性帕金森病(PD)有关,最常见的与年龄相关的运动障碍。多巴胺传递的功能障碍有助于PD相关的运动症状。有趣的是,与产生多巴胺的黑质纹状体多巴胺能神经元相比,LRRK2在多巴胺感受纹状体棘突投射神经元(SPN)中更丰富。衰老是PD和其他神经退行性疾病的最重要风险身分。然而,LRRK2是否调制SPN的老化还有待确定。
我们对从2和12月龄的Lrrk2敲除(Lrrk2-/-)和对照(Lrrk2+/+)小鼠分离的纹状体组织进行了RNA测序(RNA-seq)分析。我们检查了SPN核DNA损伤和表观遗传修饰;SPN核,细胞体和树突形态;以及2至24个月大的Lrrk2/和Lrrk2-/-小鼠的运动和运动技能学习。考虑到未来机理研究的细胞培养强度,我们还对来自Lrrk2+/+和Lrrk2-/-小鼠以及与PD相关的Lrrk2G2019S和R1441C突变小鼠的原代培养SPN进行了初步研究.
Lrrk2缺乏加速核肥大和诱导树突萎缩,衰老过程中SPN的体细胞肥大和核内陷。此外,在衰老的Lrk2-/-纹状体神经元中也观察到核DNA损伤增加和组蛋白甲基化异常,以及调节神经元兴奋性的分子途径的改变,基因组稳定性和蛋白质稳态。此外,PD相关的Lrrk2G2019S突变体和LRRK2激酶抑制剂均导致核肥大,而Lrrk2R1441C突变体和γ-氨基丁酸A型受体(GABA-AR)抑制剂促进了培养的SPN的核内陷。另一方面,神经元兴奋性的抑制阻止了培养的Lrrk2-/-和R1441CSPN中核内陷的形成。
我们的发现支持LRRK2在正常衰老过程中维持核结构完整性和基因组稳定性的重要生理功能。提示PD相关的LRRK2突变可能通过加速衰老过程引起神经元结构的恶化。
Multiple missense mutations in Leucine-rich repeat kinase 2 (LRRK2) are associated with familial forms of late onset Parkinson\'s disease (PD), the most common age-related movement disorder. The dysfunction of dopamine transmission contributes to PD-related motor symptoms. Interestingly, LRRK2 is more abundant in the dopaminoceptive striatal spiny projection neurons (SPNs) compared to the dopamine-producing nigrostriatal dopaminergic neurons. Aging is the most important risk factor for PD and other neurodegenerative diseases. However, whether LRRK2 modulates the aging of SPNs remains to be determined.
We conducted RNA-sequencing (RNA-seq) analyses of striatal tissues isolated from Lrrk2 knockout (Lrrk2-/-) and control (Lrrk2+/+) mice at 2 and 12 months of age. We examined SPN nuclear DNA damage and epigenetic modifications; SPN nuclear, cell body and dendritic morphology; and the locomotion and motor skill learning of Lrrk2+/+ and Lrrk2-/- mice from 2 to 24 months of age. Considering the strength of cell cultures for future mechanistic studies, we also performed preliminary studies in primary cultured SPNs derived from the Lrrk2+/+ and Lrrk2-/- mice as well as the PD-related Lrrk2 G2019S and
R1441C mutant mice.
Lrrk2-deficiency accelerated nuclear hypertrophy and induced dendritic atrophy, soma hypertrophy and nuclear invagination in SPNs during aging. Additionally, increased nuclear DNA damage and abnormal histone methylations were also observed in aged Lrrk2-/- striatal neurons, together with alterations of molecular pathways involved in regulating neuronal excitability, genome stability and protein homeostasis. Furthermore, both the PD-related Lrrk2 G2019S mutant and LRRK2 kinase inhibitors caused nuclear hypertrophy, while the Lrrk2
R1441C mutant and γ-Aminobutyric acid type A receptor (GABA-AR) inhibitors promoted nuclear invagination in the cultured SPNs. On the other hand, inhibition of neuron excitability prevented the formation of nuclear invagination in the cultured Lrrk2-/- and
R1441C SPNs.
Our findings support an important physiological function of LRRK2 in maintaining nuclear structure integrity and genomic stability during the normal aging process, suggesting that PD-related LRRK2 mutations may cause the deterioration of neuronal structures through accelerating the aging process.