Department of Anatomy, College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, China.
Department of Morphology, College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, China.
J Neuroinflammation. 2024 Nov 14;21(1):296. doi: 10.1186/s12974-024-03284-4.
The aging of the central nervous system(CNS) is a primary contributor to neurodegenerative diseases in older individuals and significantly impacts their quality of life. Neuroinflammation, characterized by activation of microglia(MG) and release of cytokines, is closely associated with the onset of these neurodegenerative diseases. The activated status of MG is modulated by specifically programmed metabolic changes under various conditions. Succinylation, a novel post-translational modification(PTM) mainly involved in regulating mitochondrial energy metabolism pathways, remains unknown in its role in MG activation and aging. In the present study, we found that succinylation levels were significantly increased both during aging and upon lipopolysaccharide-induced(LPS-induced) MG activation undergoing metabolic reprogramming. Up-regulated succinylation induced by sirtuin 5 knockdown(Sirt5 KD) in microglial cell line BV2 resulted in significant up-regulation of aging-related genes, accompanied by impaired mitochondrial adaptability and a shift towards glycolysis as a major metabolic pathway. Furthermore, after LPS treatment, Sirt5 KD BV2 cells exhibited increased generation of reactive oxygen species(ROS), accumulation of lipid droplets, and elevated levels of lipid peroxidation. By employing immunoprecipitation, introducing point mutation to critical succinylation sites, and conducting enzyme activity assays for succinate dehydrogenase(SDH) and trifunctional enzyme subunit alpha(ECHA), we demonstrated that succinylation plays a regulatory role in modulating the activities of these mitochondrial enzymes. Finally, down-regulation the succinylation levels achieved through administration of succinyl phosphonate(SP) led to amelioration of MG senescence in vitro and neuroinflammation in vivo. To our knowledge, our data provide preliminary evidence indicating that up-regulated succinylation modifications elicit a senescence phenotype in MG through alterations in energy metabolism. Moreover, these findings suggest that manipulation of succinylation levels may offer valuable insights into the treatment of aging-related neuroinflammation.
中枢神经系统（CNS）的老化是导致老年人神经退行性疾病的主要原因，极大地影响了他们的生活质量。神经炎症的特征是小胶质细胞（MG）的激活和细胞因子的释放，与这些神经退行性疾病的发生密切相关。MG 的激活状态受到各种条件下特定编程代谢变化的调节。琥珀酰化是一种新的翻译后修饰（PTM），主要参与调节线粒体能量代谢途径，但在 MG 激活和衰老中的作用尚不清楚。在本研究中，我们发现琥珀酰化水平在衰老过程中和脂多糖诱导（LPS 诱导）的 MG 激活时均显著增加，同时发生代谢重编程。小胶质细胞系 BV2 中 Sirtuin 5 敲低（Sirt5 KD）引起的上调琥珀酰化导致与衰老相关的基因显著上调，同时伴随着线粒体适应性受损和糖酵解作为主要代谢途径的转变。此外，在 LPS 处理后，Sirt5 KD BV2 细胞表现出活性氧（ROS）生成增加、脂滴积累和脂质过氧化水平升高。通过免疫沉淀、引入关键琥珀酰化位点的点突变以及琥珀酸脱氢酶（SDH）和三功能酶亚基α（ECHA）的酶活性测定，我们证明琥珀酰化在调节这些线粒体酶的活性中起调节作用。最后，通过给予琥珀酰膦酸盐（SP）来降低琥珀酰化水平，可改善体外 MG 衰老和体内神经炎症。据我们所知，我们的数据提供了初步证据，表明上调的琥珀酰化修饰通过改变能量代谢在 MG 中引发衰老表型。此外，这些发现表明，操纵琥珀酰化水平可能为治疗与衰老相关的神经炎症提供有价值的见解。
