Department of Orthopaedics, Provincial Hospital Affiliated to Shandong University, Jinan, P.R. China.
J Cell Biochem. 2013 Dec;114(12):2738-45. doi: 10.1002/jcb.24622.
Tumor necrosis factor (TNF)-alpha is a key cytokine regulator of bone and mediates inflammatory bone loss. The molecular signaling that regulates bone loss downstream of TNF-alpha is poorly defined. Recent studies implicated an important role of microRNAs (miRNAs) in TNF-alpha-mediated bone metabolism, including osteoblasts differentiation, osteoclasts differentiation and apoptosis. However, there are very few studies on the complex regulation of miRNAs during TNF-alpha-induced osteoblasts apoptosis. In the present study, the clonal murine osteoblastic cell line, MC3T3-E1, was used. We screened for differentially expressed miRNAs during TNF-alpha induced MC3T3-E1 cell apoptosis and identified microRNA-23a as a potential inhibitor of apoptosis. To delineate the role of microRNA-23a in apoptosis, we respectively silenced and overexpressed microRNA-23a in MC3T3-E1 cells. We found that microRNA-23a depletion significantly enhances TNF-alpha-induced MC3T3-E1 cell apoptosis and over-expressing microRNA-23a remarkably attenuates this phenomenon. Mechanistic studies showed that microRNA-23a inhibits Fas expression through a microRNA-23a-binding site within the 3'-untranslational region of Fas. The post-transcriptional repression of Fas was further confirmed by luciferase reporter assay. These results showed that microRNA-23a, an important protecting factor, plays a significant role in the process of TNF-alpha induced MC3T3-E1 cell apoptosis, by regulating Fas expression.
肿瘤坏死因子 (TNF)-α 是一种关键的细胞因子调节剂，可调节骨骼，并介导炎症性骨丢失。目前，TNF-α 下游调节骨丢失的分子信号通路还未完全明确。最近的研究表明 microRNAs（miRNAs）在 TNF-α 介导的骨代谢中发挥重要作用，包括成骨细胞分化、破骨细胞分化和凋亡。然而，关于 TNF-α 诱导成骨细胞凋亡过程中 miRNAs 的复杂调控，目前研究较少。本研究中，我们选用克隆鼠成骨细胞系 MC3T3-E1。我们筛选了 TNF-α 诱导 MC3T3-E1 细胞凋亡过程中的差异表达 miRNAs，并鉴定 microRNA-23a 是一种潜在的凋亡抑制剂。为了阐明 microRNA-23a 在凋亡中的作用，我们分别在 MC3T3-E1 细胞中沉默和过表达 microRNA-23a。我们发现，microRNA-23a 耗竭可显著增强 TNF-α 诱导的 MC3T3-E1 细胞凋亡，而过表达 microRNA-23a 则显著减弱这种现象。机制研究表明，microRNA-23a 通过 Fas 3'-非翻译区的 miRNA-23a 结合位点抑制 Fas 表达。荧光素酶报告基因检测进一步证实了 Fas 的转录后抑制。这些结果表明，microRNA-23a 作为一种重要的保护因子，通过调节 Fas 表达，在 TNF-α 诱导的 MC3T3-E1 细胞凋亡过程中发挥重要作用。
