Department of Molecular Medicine, College of Medicine, Ewha Womans University, 25 Magokdong-ro-2-gil, Gangseo-gu, Seoul 07804, Korea.
Global Business Development Division, Kangstem Biotech Co., Ltd., 512 Teheran-ro, Gangnam-gu, Seoul 06179, Korea.
Cells. 2022 Feb 3;11(3):534. doi: 10.3390/cells11030534.
Our previous study found that the level of CCN1 increases as osteogenic differentiation progresses in tonsil-derived mesenchymal stem cells (TMSCs). This study investigated how CCN1 is regulated through HDAC inhibition in TMSCs and their relationship with osteogenesis. Valproic acid (VPA) (1-5 mM), a well-known histone deacetylase (HDAC) inhibitor, strongly inhibited TMSC proliferation without altering MSC-specific surface markers, CD14, 34, 45, 73, 90 and 105. However, CD146 expression increased at 5 mM VPA. VPA increased osteogenic differentiation of TMSCs but decreased adipogenesis and chondrogenesis, as evidenced by the cell-specific staining of differentiation. The former was validated by the increased osteocalcin (OCN). The changes in CCN1 by VPA was biphasic; it increased until 48 h and decreased thereafter. Knockdown of CCN1 by using siRNA inhibited the osteogenic effect of VPA. VPA had no effect on mRNA expression, but inhibition of protein synthesis by cycloheximide showed that VPA slowed down the CCN1 protein degradation. Moreover, overexpression of HDAC1 completely inhibited VPA-induced CCN1. Our results indicate that VPA inhibits the HDAC1, inducing CCN1 protein stability rather than gene expression, thereby promoting osteogenic differentiation of TMSCs. These findings present the noble implication of VPA as an inhibitor of HDAC1 to facilitate CCN1-induced osteogenic differentiation of MSCs.
我们之前的研究发现，在扁桃体间充质干细胞（TMSCs）的成骨分化过程中，CCN1 的水平会增加。本研究探讨了 CCN1 如何通过 TMSCs 中的组蛋白去乙酰化酶（HDAC）抑制来调节及其与成骨的关系。丙戊酸（VPA）（1-5 mM）是一种众所周知的组蛋白去乙酰化酶（HDAC）抑制剂，它强烈抑制 TMSC 增殖，而不改变 MSC 特异性表面标志物 CD14、34、45、73、90 和 105。然而，在 5 mM VPA 下，CD146 的表达增加。VPA 增加了 TMSC 的成骨分化，但减少了脂肪生成和软骨生成，这可通过分化的细胞特异性染色来证明。前者通过骨钙素（OCN）的增加得到验证。VPA 对 CCN1 的影响呈双相变化；在 48 小时内增加，之后减少。使用 siRNA 敲低 CCN1 抑制了 VPA 的成骨作用。VPA 对 mRNA 表达没有影响，但用环己酰亚胺抑制蛋白质合成表明，VPA 减缓了 CCN1 蛋白的降解。此外，HDAC1 的过表达完全抑制了 VPA 诱导的 CCN1。我们的结果表明，VPA 抑制 HDAC1，诱导 CCN1 蛋白稳定性而不是基因表达，从而促进 TMSCs 的成骨分化。这些发现表明 VPA 作为 HDAC1 抑制剂具有促进 MSC 中 CCN1 诱导的成骨分化的重要意义。
