Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing 100081, P.R. China.
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing 100191, P.R. China.
Biosci Rep. 2021 Nov 26;41(11). doi: 10.1042/BSR20211148.
Lysine methyltransferase 2D (KMT2D), as one of the key histone methyltransferases responsible for histone 3 lysine 4 methylation (H3K4me), has been proved to be the main pathogenic gene of Kabuki syndrome disease. Kabuki patients with KMT2D mutation frequently present various dental abnormalities, including abnormal tooth number and crown morphology. However, the exact function of KMT2D in tooth development remains unclear. In this report, we systematically elucidate the expression pattern of KMT2D in early tooth development and outline the molecular mechanism of KMT2D in dental epithelial cell line. KMT2D and H3K4me mainly expressed in enamel organ and Kmt2d knockdown led to the reduction in cell proliferation activity and cell cycling activity in dental epithelial cell line (LS8). RNA-sequencing (RNA-seq) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis screened out several important pathways affected by Kmt2d knockdown including Wnt signaling. Consistently, Top/Fop assay confirmed the reduction in Wnt signaling activity in Kmt2d knockdown cells. Nuclear translocation of β-catenin was significantly reduced by Kmt2d knockdown, while lithium chloride (LiCl) partially reversed this phenomenon. Moreover, LiCl partially reversed the decrease in cell proliferation activity and G1 arrest, and the down-regulation of Wnt-related genes in Kmt2d knockdown cells. In summary, the present study uncovered a pivotal role of histone methyltransferase KMT2D in dental epithelium proliferation and cell cycle homeostasis partially through regulating Wnt/β-catenin signaling. The findings are important for understanding the role of KMT2D and histone methylation in tooth development.
赖氨酸甲基转移酶 2D（KMT2D）作为负责组蛋白 3 赖氨酸 4 甲基化（H3K4me）的关键组蛋白甲基转移酶之一，已被证实是歌舞伎综合征疾病的主要致病基因。KMT2D 突变的歌舞伎综合征患者常表现出各种牙齿异常，包括牙齿数量和牙冠形态异常。然而，KMT2D 在牙齿发育中的确切功能仍不清楚。在本报告中，我们系统地阐明了 KMT2D 在早期牙齿发育中的表达模式，并概述了 KMT2D 在牙上皮细胞系中的分子机制。KMT2D 和 H3K4me 主要在釉质器官中表达，Kmt2d 敲低导致牙上皮细胞系（LS8）中的细胞增殖活性和细胞周期活性降低。RNA 测序（RNA-seq）和京都基因与基因组百科全书（KEGG）富集分析筛选出几个受 Kmt2d 敲低影响的重要通路，包括 Wnt 信号通路。一致地，Top/Fop 测定证实 Kmt2d 敲低细胞中的 Wnt 信号活性降低。β-catenin 的核易位被 Kmt2d 敲低显著减少，而氯化锂（LiCl）部分逆转了这一现象。此外，LiCl 部分逆转了 Kmt2d 敲低细胞中细胞增殖活性和 G1 期阻滞的降低，以及 Wnt 相关基因的下调。综上所述，本研究揭示了组蛋白甲基转移酶 KMT2D 在牙上皮细胞增殖和细胞周期平衡中的关键作用，部分通过调节 Wnt/β-catenin 信号通路。这些发现对于理解 KMT2D 和组蛋白甲基化在牙齿发育中的作用具有重要意义。
