Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, 61186, South Korea.
Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, 61186, South Korea.
Sci Rep. 2017 Aug 14;7(1):8060. doi: 10.1038/s41598-017-08868-0.
Plant homeodomain finger protein 20 (PHF20), a methyl lysine effector protein, is a component MOF-NSL lysine acetyltranferase complex. Global deletion of PHF20 has shown spinal bone defects and reduced skeletal formation. However, the molecular basis of PHF20 involved in skeletal development has not been elucidated yet. The objective of this study was to determine the role of PHF20 in osteoblast differentiation and mineralization. Expression of PHF20 was gradually increased during osteoblast differentiation. Overexpression of PHF20 enhanced ALP activity and mineralized nodule formation as well as the expression of osteogenic markers including Runx2. In contrast, inhibition of PHF20 expression reduced osteoblast differentiation and mineralization. Mechanistically, PHF20 increased the promoter activity of osteogenic genes including Og2, Alp, and Bsp through direct association with Runx2. Moreover, PHF20 increased the enrichment of H3K4me3 on the promoter of Runx2 followed by increased Runx2 promoter activity. Interestingly, Bix-01294, a histone methylation inhibitor, decreased mineralized nodule formation through decreasing the levels of H3K4me3 and Runx2. Overexpression of PHF20 restored the Bix-01294 effects. Taken together, these results indicate that methyl lysine-binding protein PHF20 might be a novel regulator of osteoblast differentiation.
植物同源结构域指蛋白 20（PHF20）是一种甲基赖氨酸效应蛋白，是 MOF-NSL 赖氨酸乙酰转移酶复合物的组成部分。PHF20 的全局缺失已显示出脊柱骨缺陷和骨骼形成减少。然而，PHF20 参与骨骼发育的分子基础尚未阐明。本研究的目的是确定 PHF20 在成骨细胞分化和矿化中的作用。PHF20 的表达在成骨细胞分化过程中逐渐增加。PHF20 的过表达增强了碱性磷酸酶（ALP）活性和矿化结节形成以及成骨标志物（包括 Runx2）的表达。相反，抑制 PHF20 的表达降低了成骨细胞分化和矿化。从机制上讲，PHF20 通过与 Runx2 直接结合，增加了包括 Og2、Alp 和 Bsp 在内的成骨基因的启动子活性。此外，PHF20 增加了 H3K4me3 在 Runx2 启动子上的富集，随后增加了 Runx2 启动子活性。有趣的是，组蛋白甲基化抑制剂 Bix-01294 通过降低 H3K4me3 和 Runx2 的水平减少了矿化结节的形成。PHF20 的过表达恢复了 Bix-01294 的作用。总之，这些结果表明，甲基赖氨酸结合蛋白 PHF20 可能是成骨细胞分化的一种新型调节因子。
