Nonresolving inflammation causes irreversible damage to periodontal ligament stem cells (PDLSCs) and impedes alveolar bone restoration. The impaired tissue regeneration ability of stem cells is associated with abnormal mitochondrial metabolism. However, the impact of specific metabolic alterations on the differentiation process of PDLSCs remains to be understood. In this study, we found that inflammation altered the metabolic flux of the tricarboxylic acid cycle and induced the accumulation of fumarate through metabolic testing and metabolic flux analysis. Transcriptome sequencing revealed the potential of fumarate in modulating epigenetics. Specifically, histone methylation typically suppresses the expression of genes related to osteogenesis. Fumarate was found to impede the osteogenic differentiation of PDLSCs that exhibited high levels of H3K9me3. Various techniques, including assay for transposase-accessible chromatin with high-throughput sequencing, chromatin immunoprecipitation sequencing, and RNA sequencing, were used to identify the target genes regulated by H3K9me3. Mechanistically, accumulated fumarate inhibited lysine-specific demethylase 4B (KDM4B) activity and increased H3K9 methylation, thus silencing asporin gene transcription. Preventing fumarate from binding to the histone demethylase KDM4B with α-ketoglutarate effectively restored the impaired osteogenic capacity of PDLSCs and improved alveolar bone recovery. Collectively, our research has revealed the significant impact of accumulated fumarate on the regulation of osteogenesis in stem cells, suggesting that inhibiting fumarate production could be a viable therapeutic approach for treating periodontal diseases.

中文翻译：

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富马酸盐通过调节 H3K9 甲基化抑制牙槽骨修复


未消退的炎症会对牙周韧带干细胞 （PDLSCs） 造成不可逆的损伤，并阻碍牙槽骨修复。干细胞组织再生能力受损与线粒体代谢异常有关。然而，特定代谢改变对 PDLSCs 分化过程的影响仍有待了解。在这项研究中，我们发现炎症改变了三羧酸循环的代谢通量，并通过代谢测试和代谢通量分析诱导了富马酸盐的积累。转录组测序揭示了富马酸盐在调节表观遗传学方面的潜力。具体来说，组蛋白甲基化通常会抑制与成骨相关的基因的表达。发现富马酸盐阻碍了表现出高水平 H3K9me3 的 PDLSCs 的成骨分化。使用各种技术，包括高通量测序检测转座酶可及染色质、染色质免疫沉淀测序和 RNA 测序，以鉴定受 H3K9me3 调控的靶基因。从机制上讲，积累的富马酸抑制赖氨酸特异性脱甲基酶 4B （KDM4B） 活性并增加 H3K9 甲基化，从而沉默 asporin 基因转录。用 α-酮戊二酸阻止富马酸盐与组蛋白去甲基化酶 KDM4B 结合，有效恢复了 PDLSCs 受损的成骨能力并改善了牙槽骨恢复。总的来说，我们的研究揭示了积累的富马酸盐对干细胞成骨调节的显着影响，表明抑制富马酸盐的产生可能是治疗牙周病的可行治疗方法。