Background/Aims: There have been many studies on the etiology of osteoarthritis (OA) with regard to the function of inflammatory cytokines, the process of cartilage degradation, the function of miR-146a, hypoxia stimulation and autophagy in OA chondrocytes, but there have been no reports on the relationship between miR-146a and autophagy in cartilage, especially under hypoxia. This study aimed to confirm the relationship of miR-146a and autophagy in cartilage under hypoxia. Methods: Chondrocytes were treated by hypoxia gradients, and the main factors including HIF-1α, HIF-2α, miR-146a and Bcl-2 and autophagy markers ULK-1, ATG-5 were detected by quantitative PCR (Q-PCR) and western blotting. The autophagy marker LC-3 was detected by immunofluorescence. The reciprocal effects between miR-146a and Bcl-2 were confirmed by several combinations of shRNAs and adenovirus-gene systems followed by Q-PCR and western blot detection. Results: Hypoxia maintained the chondrocytes phenotype and promoted autophagy and miR-146a expression via HIF-1α, but not HIF-2α, while miR-146a did not reversely affect HIF-1α. The autophagy induced by hypoxia through HIF-1α, miR-146a and Bcl-2. Simply, hypoxia induced HIF-1α, and HIF-1α increased miR-146a, but miR-146a suppressed Bcl-2, an autophagy inhibitor. While Bcl-2 affected neither HIF-1α nor miR-146a. The absence of both HIF-1α and miR-146a or Bcl-2 over-expression inhibited hypoxia-induced autophagy. Conclusion: HIF-1α, miR-146a and Bcl-2 play crucial roles during hypoxia-induced autophagy, Hypoxia, HIF-1α and miR-146a promote chondrocytes autophagy via depressing Bcl-2. We conclude that miR-146a may serve as a novel therapeutic target for protecting cartilage from degeneration in OA.

中文翻译：

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低氧诱导的MicroRNA-146a通过Bcl-2促进软骨细胞自噬。

背景/目的：关于骨关节炎（OA）的病因学，已经进行了许多研究，涉及炎性细胞因子的功能，软骨降解的过程，miR-146a的功能，缺氧刺激和OA软骨细胞自噬的研究，但是尚无关于miR-146a与软骨自噬之间关系的报道，尤其是在缺氧条件下。本研究旨在证实低氧条件下miR-146a与软骨自噬的关系。方法：采用缺氧梯度处理软骨细胞，采用定量PCR（Q-PCR）检测HIF-1α，HIF-2α，miR-146a和Bcl-2以及自噬标记物ULK-1，ATG-5的主要影响因素。蛋白质印迹。通过免疫荧光检测自噬标记物LC-3。miR-146a和Bcl-2之间的相互影响通过shRNA和腺病毒基因系统的几种组合，随后的Q-PCR和Western blot检测得到证实。结果：缺氧通过HIF-1α维持软骨细胞表型并促进自噬和miR-146a表达，但不通过HIF-2α促进，而miR-146a不会逆向影响HIF-1α。低氧通过HIF-1α，miR-146a和Bcl-2诱导自噬。简单地说，低氧诱导的HIF-1α和HIF-1α增加了miR-146a，但miR-146a抑制了自噬抑制剂Bcl-2。而Bcl-2既不影响HIF-1α，也不影响miR-146a。HIF-1α和miR-146a或Bcl-2的过度表达均抑制缺氧诱导的自噬。结论：HIF-1α，miR-146a和Bcl-2在缺氧诱导的自噬，缺氧，HIF-1α和miR-146a通过抑制Bcl-2促进软骨细胞自噬。我们得出的结论是，miR-146a可以作为保护软骨免于OA变性的新型治疗靶标。