Methylsulfonylmethane Inhibits RANKL-Induced Osteoclastogenesis in BMMs by Suppressing NF-κB and STAT3 Activities.
Methylsulfonylmethane Inhibits RANKL-Induced Osteoclastogenesis in BMMs by Suppressing NF-κB and STAT3 Activities.
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DOI：
10.1371/journal.pone.0159891
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Yang YM
中科院分区：
文献类型：
--
作者：
Joung YH;Darvin P;Kang DY;Sp N;Byun HJ;Lee CH;Lee HK;Yang YM
破骨细胞的分化依赖于受体激活剂NF-kB配体（RANKL）和巨噬细胞集落刺激因子（M-CSF）的活性。鉴于RANKL在破骨细胞形成和骨吸收中起着至关重要的作用，任何改变其活性的新化合物都将被预测为具有治疗骨质流失相关疾病的潜力。甲基磺酰甲烷（MSM）是一种天然存在的含硫化合物，具有充分证明的抗氧化和抗炎特性；目前，其对破骨细胞分化的影响尚不清楚。我们试图研究MSM是否可以调节破骨细胞的发生，如果是，其作用机制。在这项研究中，我们研究了MSM对rankl诱导的破骨细胞分化的影响，以及STAT3参与破骨基因标记物的表达。这些实验使用骨髓源性巨噬细胞（BMMs）和细胞系材料进行，同时分析了蛋白质和mRNA水平以及信号通路活性。虽然MSM对破骨细胞前体没有毒性，但MSM明显抑制rankl诱导的TRAP活性、多核破骨细胞形成和骨吸收活性。此外，MSM抑制了几个破骨细胞发生相关标记基因的表达，包括TRAF6、c-Fos、NFATc1、cathepsin K和OSCAR。MSM介导的rankl诱导的破骨细胞生成的抑制涉及ITAM信号效应如PLCγ和Syk的抑制，通过阻断NF-kB而不是MAPK活性。此外，MSM抑制rankl诱导的STAT3 Ser727磷酸化。使用shRNAs敲低STAT3导致在STAT3缺失的细胞中，rankl介导的Ser727 STAT3和TRAF6磷酸化减少。此外，MSM和STAT3敲低显著降低了rankl诱导的破骨标志物基因的表达。综上所述，这些结果表明STAT3在rankl诱导的破骨细胞形成中起关键作用，MSM可以通过阻断NF-kB和STAT3活性来减弱rankl诱导的破骨细胞形成。
Osteoclast differentiation is dependent on the activities of receptor activator NF-kB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Given that RANKL plays a critical role in osteoclast formation and bone resorption, any new compounds found to alter its activity would be predicted to have therapeutic potential for disorders associated with bone loss. Methylsulfonylmethane (MSM) is a naturally occurring sulfur compound with well-documented anti-oxidant and anti-inflammatory properties; currently its effects on osteoclast differentiation are unknown. We sought to investigate whether MSM could regulate osteoclastogenesis, and if so, its mechanism of action. In this study, we investigated the effects of MSM on RANKL-induced osteoclast differentiation, together with STAT3’s involvement in the expression of osteoclastic gene markers. These experiments were conducted using bone marrow derived macrophages (BMMs) and cell line material, together with analyses that interrogated both protein and mRNA levels, as well as signaling pathway activity. Although MSM was not toxic to osteoclast precursors, MSM markedly inhibited RANKL-induced TRAP activity, multinucleated osteoclast formation, and bone resorptive activity. Additionally, the expression of several osteoclastogenesis-related marker genes, including TRAF6, c-Fos, NFATc1, cathepsin K, and OSCAR were suppressed by MSM. MSM mediated suppression of RANKL-induced osteoclastogenesis involved inhibition of ITAM signaling effectors such as PLCγ and Syk, with a blockade of NF-kB rather than MAPK activity. Furthermore, MSM inhibited RANKL-induced phosphorylation of STAT3 Ser727. Knockdown of STAT3 using shRNAs resulted in reduced RANKL-mediated phosphorylation of Ser727 STAT3, and TRAF6 in cells for which depletion of STAT3 was confirmed. Additionally, the expression of RANKL-induced osteoclastogenic marker genes were significantly decreased by MSM and STAT3 knockdown. Taken together, these results indicate that STAT3 plays a pivotal role in RANKL-induced osteoclast formation, and that MSM can attenuate RANKL-induced osteoclastogenesis by blocking both NF-kB and STAT3 activity.