Moderate Fluid Shear Stress Regulates Heme Oxygenase-1 Expression to Promote Autophagy and ECM Homeostasis in the Nucleus Pulposus Cells
Moderate Fluid Shear Stress Regulates Heme Oxygenase-1 Expression to Promote Autophagy and ECM Homeostasis in the Nucleus Pulposus Cells
复制标题
中等流体剪切应力调节血红素加氧酶 1 表达，促进髓核细胞自噬和 ECM 稳态
DOI：
10.3389/fcell.2020.00127
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发表时间：
2020-03-03
影响因子：
5.5
通讯作者：
Cao, Hulling
中科院分区：
文献类型：
--
作者：
Chen, Sheng;Qin, Lei;Cao, Hulling
在脊椎动物中，髓核作为椎间盘的重要组成部分，经常受到流体切应力的影响，然而流体切应力调节髓核稳态的分子机制(S)却知之甚少。在这里，我们表明，FSS调节细胞外基质(ECM)在NP细胞内的稳态。中等剂量的FSS(12dyne/cm(2))可使大鼠NP细胞COL2a1和Aggrecan的硫酸糖胺聚糖(SGAG)含量和蛋白水平升高，而基质金属蛋白酶13(MMP13)和带血栓反应蛋白5的去整合素和金属蛋白酶(ADMATS5)的含量和蛋白水平降低，而较高剂量(24dyne/cm(2))的FSS则相反。RNA测序分析、实时定量RT-PCR分析和Western blotting结果表明，HO-1是NP细胞中FSS作用的关键下游调节因子。HO-1基因敲除可消除FSS诱导的NP细胞ECM蛋白产生和SGAG含量的改变，而HO-1诱导的这种改变是可逆的。此外，FSS通过增加Lc3-II/Lc3-I比值、Beclin-1蛋白水平以及自噬小体和自溶酶体的形成来激活自噬途径，从而以HO-1依赖的方式调节ECM蛋白和SGAG的产生。最后，我们证明了鞭毛内转运(IFT)88是原生纤毛的核心运输蛋白，在HO-1介导的自噬激活以及FSS处理的NP细胞中ECM蛋白和SGAG的产生中起关键作用。因此，我们首次证明了FSS通过依赖于HO-1激活NP细胞中的自噬，在维持ECM动态平衡方面发挥了重要作用。
In vertebrate, the nucleus pulposus (NP), which is an essential component of the intervertebral disk, is constantly impacted by fluid shear stress (FSS); however, molecular mechanism(s) through which FSS modulates the NP homeostasis is poorly understood. Here we show that FSS regulates the extracellular matrix (ECM) homeostasis in NP cells. A moderate dose of FSS (i.e., 12 dyne/cm(2)) increases the sulfated glycosaminoglycan (sGAG) content and protein levels of Col2a1 and Aggrecan and decreases those of matrix metalloproteinase 13 (MMP13) and a disintegrin and metalloproteinase with thrombospondin motif 5 (ADMATS5) in rat NP cells, while a higher dose of FSS (i.e., 24 dyne/cm(2)) displays opposite effects. Results from RNA sequencing analysis, quantitative real-time RT-PCR analysis and western blotting establish that the heme oxygenase-1 (HO-1) is a key downstream mediator of the FSS actions in NP cells. HO-1 knockdown abolishes FSS-induced alterations in ECM protein production and sGAG content in NP cells, which is reversed by HO-1 induction. Furthermore, FSS activates the autophagic pathway by increasing the LC3-II/LC3-I ratio, Beclin-1 protein level, and formation of autophagosome and autolysosome and thereby regulates ECM protein and sGAG production in a HO-1 dependent manner. Finally, we demonstrate that the intraflagellar transport (IFT) 88, a core trafficking protein of primary cilia, is critically involved in the HO-1-mediated autophagy activation and ECM protein and sGAG production in FSS-treated NP cells. Thus, we for the first time demonstrate that FSS plays an important role in maintaining ECM homeostasis through HO-1-dependent activation of autophagy in NP cells.