Department of Orthopaedics, the Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
Harbin First Hospital Community Health Center, Harbin, Heilongjiang, China.
Life Sci. 2020 Aug 1;254:116801. doi: 10.1016/j.lfs.2019.116801. Epub 2019 Aug 28.
The study aimed to investigate the regulation of long noncoding RNA (lncRNA), Metastasis associated lung adenocarcinoma transcript 1 (MALAT1) in osteoarthritis (OA) development. Isolated rat chondrocytes treated with lipopolysaccharide (LPS) were used as OA cell model. Results from quantitative real-time PCR (Q-PCR) showed that, in OA patients and OA cell model, the expression of MALAT1 and PI3K was clearly reduced, while the miR-146a levels were increased. Next, MALAT1 was silenced in LPS-treated chondrocytes. Following with MALAT1 silencing, the generation of Cyclooxygenase-2 (COX-2), Interleukin-6 (IL-6) and Matrix metallopeptidase-13 (MMP-13) were promoted, while the level of type II collagen (COL2) was inhibited. Moreover, MALAT1 silencing caused a significant reduction in the proliferative rate of LPS-treated chondrocytes through inducing apoptosis. Bioinformatics prediction and dual-luciferase reporter assay (DLRA) results showed that MALAT1 targets miR-146a. MALAT1 silencing also resulted in the upregulation of miR-146a. Further studies revealed that miR-146a has the opposite effect on MALAT1, and its inhibition can antagonize the function of MALAT1 silencing on cell proliferation and apoptosis. Additionally, the 3'-UTR of the Phosphoinositide 3-kinase (PI3K) gene was found to be a target of miR-146a, while PI3K protein and mRNA expression, as well as the activation of downstream Akt and mammalian target of rapamycin (mTOR) were clearly reduced upon transfection with a miR-146a mimic. These results show that MALAT1 can modulate ECM catabolism, inflammation, and especially apoptosis in chondrocytes treated with LPS, which targets PI3K/Akt/mTOR to eventually regulate the progression of OA. Our findings provide a novel regulatory mechanism of MALAT1 in OA.
本研究旨在探讨长链非编码 RNA（lncRNA），转移相关肺腺癌转录物 1（MALAT1）在骨关节炎（OA）发展中的调节作用。用脂多糖（LPS）处理分离的大鼠软骨细胞作为 OA 细胞模型。实时定量 PCR（Q-PCR）结果显示，在 OA 患者和 OA 细胞模型中，MALAT1 和 PI3K 的表达明显降低，而 miR-146a 的水平升高。接着，沉默 LPS 处理的软骨细胞中的 MALAT1。沉默 MALAT1 后，促进环氧化酶-2（COX-2）、白细胞介素-6（IL-6）和基质金属蛋白酶-13（MMP-13）的生成，同时抑制 II 型胶原（COL2）的水平。此外，沉默 MALAT1 通过诱导细胞凋亡显著降低 LPS 处理的软骨细胞的增殖率。生物信息学预测和双荧光素酶报告基因分析（DLRA）结果表明，MALAT1 靶向 miR-146a。沉默 MALAT1 也导致 miR-146a 的上调。进一步研究表明，miR-146a 对 MALAT1 具有相反的作用，其抑制作用可以拮抗 MALAT1 沉默对细胞增殖和凋亡的功能。此外，发现 Phosphoinositide 3-kinase（PI3K）基因的 3'-UTR 是 miR-146a 的靶标，而转染 miR-146a 模拟物后，PI3K 蛋白和 mRNA 表达以及下游 Akt 和哺乳动物雷帕霉素靶蛋白（mTOR）的激活明显降低。这些结果表明，沉默 MALAT1 可以调节 LPS 处理的软骨细胞中细胞外基质代谢、炎症，特别是细胞凋亡，其作用靶点是 PI3K/Akt/mTOR，从而调节 OA 的进展。我们的研究结果为 MALAT1 在 OA 中的调控机制提供了新的见解。
