Department of Orthopedics, Xinqiao Hospital, Army Military Medical University, Chongqing, 400037, China.
State Key Laboratory of Trauma, Burn and Combined Injury, Army Military Medical University, Chongqing, 400038, China.
Cell Mol Life Sci. 2024 Jan 12;81(1):24. doi: 10.1007/s00018-023-05094-y.
The accumulation of metabolites in the intervertebral disc is considered an important cause of intervertebral disc degeneration (IVDD). Lactic acid, which is a metabolite that is produced by cellular anaerobic glycolysis, has been proven to be closely associated with IVDD. However, little is known about the role of lactic acid in nucleus pulposus cells (NPCs) senescence and oxidative stress. The aim of this study was to investigate the effect of lactic acid on NPCs senescence and oxidative stress as well as the underlying mechanism. A puncture-induced disc degeneration (PIDD) model was established in rats. Metabolomics analysis revealed that lactic acid levels were significantly increased in degenerated intervertebral discs. Elimination of excessive lactic acid using a lactate oxidase (LOx)-overexpressing lentivirus alleviated the progression of IVDD. In vitro experiments showed that high concentrations of lactic acid could induce senescence and oxidative stress in NPCs. High-throughput RNA sequencing results and bioinformatic analysis demonstrated that the induction of NPCs senescence and oxidative stress by lactic acid may be related to the PI3K/Akt signaling pathway. Further study verified that high concentrations of lactic acid could induce NPCs senescence and oxidative stress by interacting with Akt and regulating its downstream Akt/p21/p27/cyclin D1 and Akt/Nrf2/HO-1 pathways. Utilizing molecular docking, site-directed mutation and microscale thermophoresis assays, we found that lactic acid could regulate Akt kinase activity by binding to the Lys39 and Leu52 residues in the PH domain of Akt. These results highlight the involvement of lactic acid in NPCs senescence and oxidative stress, and lactic acid may become a novel potential therapeutic target for the treatment of IVDD.
代谢物在椎间盘内的积累被认为是椎间盘退变（IVDD）的一个重要原因。乳酸是细胞无氧糖酵解产生的一种代谢物，已被证明与 IVDD 密切相关。然而，乳酸在核芯细胞（NPCs）衰老和氧化应激中的作用知之甚少。本研究旨在探讨乳酸对 NPCs 衰老和氧化应激的影响及其潜在机制。在大鼠中建立了穿刺诱导的椎间盘退变（PIDD）模型。代谢组学分析显示，退变椎间盘内的乳酸水平显著升高。使用过表达乳酸氧化酶（LOx）的慢病毒消除过多的乳酸可缓解 IVDD 的进展。体外实验表明，高浓度的乳酸可诱导 NPCs 衰老和氧化应激。高通量 RNA 测序结果和生物信息学分析表明，乳酸诱导 NPCs 衰老和氧化应激可能与 PI3K/Akt 信号通路有关。进一步的研究证实，高浓度的乳酸通过与 Akt 相互作用并调节其下游 Akt/p21/p27/cyclin D1 和 Akt/Nrf2/HO-1 通路，可诱导 NPCs 衰老和氧化应激。利用分子对接、定点突变和微尺度热泳动测定，我们发现乳酸可以通过与 Akt PH 结构域的 Lys39 和 Leu52 残基结合来调节 Akt 激酶活性。这些结果强调了乳酸在 NPCs 衰老和氧化应激中的作用，乳酸可能成为治疗 IVDD 的一种新的潜在治疗靶点。
