The interactions between mTOR and NF-κB: a novel mechanism mediating mechanical stretch-stimulated osteoblast differentiation
The interactions between mTOR and NF-κB: a novel mechanism mediating mechanical stretch-stimulated osteoblast differentiation
复制标题
mTOR 和 NF-κB 之间的相互作用：介导机械拉伸刺激成骨细胞分化的新机制
DOI：
10.1002/jcp.30184
复制
发表时间：
--
期刊：
影响因子：
--
通讯作者：
景达
中科院分区：
文献类型：
--
作者：
王丹;蔡静;曾照斌;高雪;邵希;丁元钧;冯雪;景达
机械牵张在体外可促进成骨细胞分化，在体内可加速骨再生，但其机制尚不清楚。最近的研究表明，mTOR和NF-κB（Akt的两个下游分子）之间的相互作用在肿瘤细胞调节中的重要性。因此，我们假设mTOR和NF-κB以及它们之间的相互作用在介导牵张诱导的成骨细胞的成骨分化中起关键作用。我们发现，机械拉伸（10%拉伸，6个周期/分钟）显著促进成骨样MG-63细胞中成骨细胞分化相关标志物（包括ALP、BMP 2、Col 1 α、OCN和Runx 2）的表达，同时伴有mTOR磷酸化和NF-κB p65磷酸化的增加以及核转位。通过拮抗剂或siRNA阻断mTOR抑制了对机械牵张的成骨相关基因表达，而抑制NF-κB进一步增加牵张诱导的成骨细胞分化。此外，在机械牵张条件下，抑制mTOR可降低MG 63细胞NF-κB的磷酸化水平，阻断NF-κB可降低mTOR的活化。共同抑制mTOR和NF-κB可消除机械牵张条件下单独抑制mTOR或NF-κB诱导的成骨分化改变，相当于机械牵张条件下成骨细胞无抑制水平。在机械牵张条件下，抑制Akt后成骨细胞成骨分化的表达水平与共抑制mTOR和NF-κB后相似。本研究首次揭示了机械牵张条件下成骨细胞中mTOR和NF-κB之间的相互联系，表明mTOR和NF-κB及其相互作用在机械牵张条件下成骨细胞内稳态的调节中起着关键作用。这些发现有助于丰富我们对成骨细胞力学转导的分子机制的基础知识，也有助于深入了解与机械拉伸相关的临床治疗方式（例如，牵张成骨）。
Mechanical stretch is known to promote osteoblast differentiation in vitro and accelerate bone regeneration in vivo, whereas the relevant mechanism remains unclear. Recent studies have shown the importance of reciprocal interactions between mTOR and NF-κB (two downstream molecules of Akt) in the regulation of tumor cells. Thus, we hypothesize that mTOR and NF-κB as well as their interconnection play a critical role in mediating stretch-induced osteogenic differentiation in osteoblasts. We herein found that mechanical stretch (10% elongation at 6 cycles/min) significantly promoted the expression of osteoblast differentiation-related markers (including ALP, BMP2, Col1α, OCN and Runx2) in osteoblast-like MG-63 cells, accompanied by increased mTOR phosphorylation and NF-κB p65 phosphorylation and nuclear translocation. Blockade of mTOR by antagonist or siRNA suppressed osteogenesis-related gene expression in response to mechanical stretch, whereas inhibition of NF-κB further increased stretch-induced osteoblast differentiation. Moreover, inhibition of mTOR decreased the phosphorylation of NF-κB, and blockade of NF-κB reduced the mTOR activation in MG63 cells under mechanical stretch. Co-inhibition of mTOR and NF-κB abolishes the alteration of osteogenic differentiation induced by single mTOR or NF-κB inhibition under mechanical stretch, which is equivalent to the non-inhibition level for osteoblasts under mechanical stretch. The expression levels of osteogenic differentiation in osteoblasts after inhibition of Akt were similar to those after co-inhibition of mTOR and NF-κB under mechanical stretch. This study for the first time reveals the reciprocal interconnection between mTOR and NF-κB in osteoblasts under mechanical stretch, and indicates that mTOR and NF-κB as well as their interactions play a key role in the regulation of cellular homeostasis of osteoblasts in response to mechanical stretch. These findings are helpful for enriching our basic knowledge of the molecular mechanisms of osteoblast mechanotransduction, and also providing insight into the clinical therapeutic modality associated with mechanical stretch (e.g., distraction osteogenesis).