Liu Hongjiang, Liu Haiquan, Meng Zuyu, Zhang Wensheng
Department of Spine, Third Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou City, PR China.
Huizhou Hospital of Guangzhou University of Chinese Medicine (Huizhou Hospital of Traditional Chinese Medicine), Huizhou City, PR China.
Histol Histopathol. 2025 May;40(5):733-743. doi: 10.14670/HH-18-813. Epub 2024 Sep 12.
Intervertebral disc (IVD) degeneration (IVDD) is characterized by structural destruction accompanied by accelerated signs of aging. This study aimed to investigate the mechanism of lysine methyltransferase 2D (KMT2D) in the proliferation, apoptosis, and inflammation of nucleus pulposus cells (NPCs) in IVDD.
Mouse-derived NPCs were cultured and induced with interleukin-1 beta (IL-1β) to establish cell models. KMT2D expression was detected by western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). KMT2D expression was interfered with, and the contents of IL-18, IL-6, and tumor necrosis factor (TNF) were detected by enzyme-linked immunosorbent assay. Cell proliferation, apoptosis, and the expression of miR-133a-5p and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2) were measured. The enrichment of KMT2D and Histone 3 Lysine 4 monomethylation/dimethylation (H3K4me1/2) on the miR-133a-5p promoter was analyzed by chromatin immunoprecipitation and qPCR. The binding of miR-133a-5p and PFKFB2 was analyzed by a dual-luciferase assay.
IL-1β treatment promoted KMT2D expression in NPCs. KMT2D knockdown reduced inflammation and apoptosis and promoted the proliferation of IL-1β-induced NPCs. Mechanistically, KMT2D upregulated miR-133a-5p expression by increasing the level of H3K4me2 at the miR-133a-5p promoter, thereby promoting the binding between miR-133a-5p and PFKFB2 and downregulating the transcription of PFKFB2. miR-133a-5p overexpression or PFKFB2 knockdown alleviated the protective effect of KMT2D knockdown on IL-1β-induced NPCs.
KMT2D promoted miR-133a-5p expression through H3K4me2 methylation, thereby promoting the binding of miR-133a-5p to PFKFB2, reducing the mRNA level of PFKFB2, promoting inflammation and apoptosis of IL-1β-induced NPCs, and inhibiting NPC proliferation.
椎间盘退变（IVDD）的特征是结构破坏并伴有加速的衰老迹象。本研究旨在探讨赖氨酸甲基转移酶2D（KMT2D）在IVDD中髓核细胞（NPCs）增殖、凋亡和炎症中的作用机制。
培养源自小鼠的NPCs，并用白细胞介素-1β（IL-1β）诱导以建立细胞模型。通过蛋白质免疫印迹法和逆转录-定量聚合酶链反应（RT-qPCR）检测KMT2D表达。干扰KMT2D表达，采用酶联免疫吸附测定法检测IL-18、IL-6和肿瘤坏死因子（TNF）的含量。检测细胞增殖、凋亡以及miR-133a-5p和6-磷酸果糖-2-激酶/果糖-2,6-二磷酸酶2（PFKFB2）的表达。通过染色质免疫沉淀和qPCR分析KMT2D和组蛋白3赖氨酸4单甲基化/二甲基化（H3K4me1/2）在miR-133a-5p启动子上的富集情况。通过双荧光素酶报告基因检测分析miR-133a-5p与PFKFB2的结合情况。
IL-1β处理促进NPCs中KMT2D表达。敲低KMT2D可减轻炎症和凋亡，并促进IL-1β诱导的NPCs增殖。机制上，KMT2D通过增加miR-133a-5p启动子处H3K4me2水平上调miR-133a-5p表达，从而促进miR-133a-5p与PFKFB2结合并下调PFKFB2转录。过表达miR-133a-5p或敲低PFKFB2可减轻KMT2D敲低对IL-1β诱导的NPCs的保护作用。
KMT2D通过H3K4me2甲基化促进miR-133a-5p表达，从而促进miR-133a-5p与PFKFB2结合，降低PFKFB2的mRNA水平，促进IL-1β诱导的NPCs炎症和凋亡，并抑制NPCs增殖。
