Background Nucleus pulposus cell (NPC) senescence in intervertebral disc (IVD) tissue is the major pathological cause during intervertebral disc degeneration (IDD). N6-methyladenosine (m6A) methylation and gut microbiota play important roles in the progression of IDD. This study investigated whether methyltransferase-like 3 (METTL3) regulates TLR2 m6A modification and gut microbiota to influence NPC senescence. Methods An IDD rat model was established by lumbar intervertebral disc puncture and NPCs were challenged with IL-1β to mimic IVD injury. IDD rats and IL-1β-exposed NPCs were treated with METTL3-interfering lentivirus and the TLR2 agonist Pam3CSK4. Compositional changes in the rat gut microbiota were analyzed and fecal microbiota transplantation procedures were used. NPC senescence, cell cycle and the expression of senescence-associated secretory phenotype (SASP) factors were assessed. The m6A enrichment of TLR2 and the binding of IGF2BP1 to TLR2 mRNA were examined. Results METTL3 and TLR2 were highly expressed in IDD rats. METTL3 silencing attenuated senescent phenotypes and reduced secretion of SASP factors. Pam3CSK4 reversed the beneficial effects of METTL3 silencing on NPC senescence and IVD injury. METTL3 stabilized TLR2 mRNA in an IGF2BP1-dependent manner. METTL3 silencing restored specific gut microbiota levels in IDD rats, which was further reversed by administration of Pam3CSK4. Fecal microbiota from METTL3 silenced IDD rats altered the pathological phenotypes of IDD rats. Conclusions These results demonstrate the beneficial effects of METTL3 silencing on NPC senescence and amelioration of IVD injury, involving modulation of TLR2 m6A modification and gut microbiota. These findings support METTL3 silencing as a potential therapeutic target for IDD.

中文翻译：

---

METTL3通过调节TLR2 m6A甲基化和肠道微生物群促进椎间盘退变中髓核细胞衰老


背景椎间盘（IVD）组织中的髓核细胞（NPC）衰老是椎间盘退变（IDD）过程中的主要病理原因。 N6-甲基腺苷 (m6A) 甲基化和肠道微生物群在 IDD 的进展中发挥重要作用。本研究调查了甲基转移酶样 3 (METTL3) 是否通过调节 TLR2 m6A 修饰和肠道微生物群来影响鼻咽癌衰老。方法采用腰椎间盘穿刺法建立IDD大鼠模型，并用IL-1β刺激NPC模拟IVD损伤。用 METTL3 干扰慢病毒和 TLR2 激动剂 Pam3CSK4 治疗 IDD 大鼠和暴露于 IL-1β 的 NPC。分析了大鼠肠道微生物群的组成变化，并使用了粪便微生物群移植程序。评估了鼻咽癌衰老、细胞周期和衰老相关分泌表型（SASP）因子的表达。检查了 TLR2 的 m6A 富集以及 IGF2BP1 与 TLR2 mRNA 的结合。结果 METTL3和TLR2在IDD大鼠中高表达。 METTL3 沉默减弱了衰老表型并减少了 SASP 因子的分泌。 Pam3CSK4 逆转了 METTL3 沉默对 NPC 衰老和 IVD 损伤的有益影响。 METTL3 以 IGF2BP1 依赖性方式稳定 TLR2 mRNA。 METTL3 沉默恢复了 IDD 大鼠的特定肠道微生物群水平，而通过施用 Pam3CSK4 可以进一步逆转这种情况。 METTL3 沉默 IDD 大鼠的粪便微生物群改变了 IDD 大鼠的病理表型。结论 这些结果证明 METTL3 沉默对 NPC 衰老和改善 IVD 损伤具有有益作用，涉及调节 TLR2 m6A 修饰和肠道微生物群。这些发现支持 METTL3 沉默作为 IDD 的潜在治疗靶点。