Department of Stomatology, Qingdao Municipal Hospital, Qingdao, China.
School of Stomatology, Dalian Medical University, Dalian, China.
Mol Biol Rep. 2022 Apr;49(4):2777-2784. doi: 10.1007/s11033-021-07089-z. Epub 2022 Jan 10.
In orthodontics, mechanical stress plays an important role in the process of bone remodeling. Mechanical stress has an effect on osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). However, the mechanism remains to be studied. The aim of this study is to investigate the effects of demethyltransferase fat mass and obesity-associated (FTO) on osteogenic differentiation of BMSCs under mechanical stress condition.
The rat BMSCs were cultured in vitro, followed by flow cytometry to identify the cell surface antigens. Osteogenic differentiation of BMSCs was induced by mechanical stress by using the flexcell tension system for 6 h every day and 3 days in total. BMSCs were transfected by using plasmid for FTO knockdown. The expression level of FTO, hypoxia-inducible factor (HIF)-1α, runt-related transcription factor 2 (RUNX2), bone morphogenetic proteins (BMPs) and alkaline phosphatase (ALP) were measured by real-time qPCR, western blotting. ALP activity were determined by ALP staining assays. The expression of FTO and HIF-1α in BMSCs with mechanical stress were significantly higher than BMSCs without mechanical stress, also, the expression of osteogenic differentiation markers were higher in BMSCs with mechanical stress. Knockdown of FTO decreased expression of osteogenic differentiation marker and ALP activity in stretched BMSCs. In addition, the expression of HIF-1α was decreased after knocking down FTO.
FTO promotes the expression of HIF-1α and osteogenic differentiation under the condition of mechanical stress. This finding may facilitate the clinical application of orthodontics and the mechanism research of mechanical stress-induced osteogenesis.
在正畸学中，机械应力在骨重塑过程中起着重要作用。机械应力对骨髓间充质干细胞（BMSCs）的成骨分化有影响。然而，其机制仍有待研究。本研究旨在探讨去甲基转移酶脂肪量和肥胖相关（FTO）在机械应力条件下对 BMSCs 成骨分化的影响。
体外培养大鼠 BMSCs，采用流式细胞术鉴定细胞表面抗原。采用 flexcell 张力系统每天对 BMSCs 施加机械应力 6 小时，共 3 天诱导其成骨分化。用质粒转染 FTO 敲低 BMSCs。通过实时 qPCR、western blot 检测 FTO、缺氧诱导因子（HIF）-1α、成骨转录因子 2（RUNX2）、骨形态发生蛋白（BMPs）和碱性磷酸酶（ALP）的表达水平。通过 ALP 染色检测 ALP 活性。机械应力作用下 BMSCs 的 FTO 和 HIF-1α 表达明显高于无机械应力作用的 BMSCs，同时机械应力作用下成骨分化标志物的表达也较高。FTO 敲低降低了拉伸 BMSCs 中成骨分化标志物和 ALP 活性的表达。此外，敲低 FTO 后 HIF-1α 的表达降低。
FTO 在机械应力条件下促进 HIF-1α 的表达和成骨分化。这一发现可能有助于正畸学的临床应用和机械应力诱导成骨的机制研究。
