Institute of Biomedicine, University of Turku, Turku, Finland.
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America.
PLoS One. 2022 Mar 7;17(3):e0265027. doi: 10.1371/journal.pone.0265027. eCollection 2022.
Epigenetic mechanisms regulate osteogenic lineage differentiation of mesenchymal stromal cells. Histone methylation is controlled by multiple lysine demethylases and is an important step in controlling local chromatin structure and gene expression. Here, we show that the lysine-specific histone demethylase Kdm1A/Lsd1 is abundantly expressed in osteoblasts and that its suppression impairs osteoblast differentiation and bone nodule formation in vitro. Although Lsd1 knockdown did not affect global H3K4 methylation levels, genome-wide ChIP-Seq analysis revealed high levels of Lsd1 at gene promoters and its binding was associated with di- and tri-methylation of histone 3 at lysine 4 (H3K4me2 and H3K4me3). Lsd1 binding sites in osteoblastic cells were enriched for the Runx2 consensus motif suggesting a functional link between the two proteins. Importantly, inhibition of Lsd1 activity decreased osteoblast activity in vivo. In support, mesenchymal-targeted knockdown of Lsd1 led to decreased osteoblast activity and disrupted primary spongiosa ossification and reorganization in vivo. Together, our studies demonstrate that Lsd1 occupies Runx2-binding cites at H3K4me2 and H3K4me3 and its activity is required for proper bone formation.
表观遗传机制调节间充质基质细胞的成骨谱系分化。组蛋白甲基化受多种赖氨酸去甲基酶控制，是控制局部染色质结构和基因表达的重要步骤。在这里，我们表明赖氨酸特异性组蛋白去甲基酶 Kdm1A/Lsd1 在成骨细胞中大量表达，其抑制作用会损害体外成骨细胞分化和骨结节形成。虽然 Lsd1 敲低不影响全局 H3K4 甲基化水平，但全基因组 ChIP-Seq 分析显示 Lsd1 在基因启动子处的水平较高，其结合与组蛋白 3 赖氨酸 4 上的二甲基化和三甲基化（H3K4me2 和 H3K4me3）有关。成骨细胞中的 Lsd1 结合位点富含 Runx2 共有基序，表明这两种蛋白之间存在功能联系。重要的是，抑制 Lsd1 活性会降低体内成骨细胞的活性。支持这一观点的是，间充质细胞靶向敲低 Lsd1 会导致成骨细胞活性降低，并破坏体内初级松质骨骨化和重组。总之，我们的研究表明 Lsd1 占据 H3K4me2 和 H3K4me3 上的 Runx2 结合位点，其活性是正常骨形成所必需的。
