BACKGROUND 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

中文翻译：

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帕金森病相关的富含亮氨酸的重复激酶 2 在衰老过程中调节纹状体投射神经元的核形态和基因组稳定性。


背景富含亮氨酸重复激酶 2 (LRRK2) 的多个错义突变与家族性迟发性帕金森病 (PD) 相关，这是最常见的与年龄相关的运动障碍。多巴胺传递功能障碍会导致帕金森病相关的运动症状。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 在多巴胺感受性纹状体棘投射神经元 (SPN) 中更为丰富。衰老是帕金森病和其他神经退行性疾病最重要的危险因素。然而，LRRK2 是否调节 SPN 的衰老仍有待确定。方法 我们对 2 月龄和 12 月龄的 Lrrk2 敲除小鼠 (Lrrk2-/-) 和对照小鼠 (Lrrk2+/+) 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 个月龄 Lrrk2+/+ 和 Lrrk2-/- 小鼠的运动和运动技能学习。考虑到细胞培养对未来机制研究的强度，我们还对源自Lrrk2+/+和Lrrk2-/-小鼠以及PD相关Lrrk2 G2019S和R1441C突变小鼠的原代培养SPN进行了初步研究。结果 Lrrk2 缺陷在衰老过程中加速了 SPN 的核肥大并诱导树突萎缩、胞体肥大和核内陷。此外，在衰老的 Lrrk2-/- 纹状体神经元中还观察到核 DNA 损伤增加和异常组蛋白甲基化，以及涉及调节神经元兴奋性、基因组稳定性和蛋白质稳态的分子途径的改变。 此外，PD相关的Lrrk2 G2019S突变体和LRRK2激酶抑制剂均引起核肥大，而Lrrk2 R1441C突变体和γ-氨基丁酸A型受体（GABA-AR）抑制剂则促进培养的SPN中的核内陷。另一方面，神经元兴奋性的抑制阻止了培养的 Lrrk2-/- 和 R1441C SPN 中核内陷的形成。结论我们的研究结果支持LRRK2在正常衰老过程中维持核结构完整性和基因组稳定性方面的重要生理功能，表明PD相关的LRRK2突变可能通过加速衰老过程导致神经元结构恶化。