Tsang Eric J, Wu Benjamin, Zuk Patricia
a Regenerative Bioengineering and Repair Laboratory, Department of Surgery , David Geffen School of Medicine at UCLA, University of California , Los Angeles , CA , USA.
b Department of Bioengineering , Henry Samueli School of Engineering and Applied Sciences, University of California , Los Angeles , CA , USA.
Connect Tissue Res. 2018 Mar;59(2):129-146. doi: 10.1080/03008207.2017.1313248. Epub 2017 May 19.
The use of pro-osteogenic growth factors, such as BMP2, in human adipose-derived stem cell (ASC) osteogenesis is well described. Because these growth factors work via signal transduction pathways, such as the mitogen-activated protein kinase (MAPK) cascade, a study of the relationship between MAPK signaling and ASC osteogenesis was conducted.
ERK, JNK, and p38MAPK activation were measured in ASCs osteo-induced using either dexamethasone or vitamin D3 and correlated with mineralization. Activation and mineralization were also measured without dexamethasone or using the glucocorticoid, cortisone. The expression of the MAPK phosphatase, MKP1, and its relationship to mineralization was also assessed. The effect of decreasing MAPK activation on mineralization through the use of exogenous inhibitors was examined along with siRNA-knockdown and adenoviral overexpression of ERK1/2. Finally, the effect of ERK1/2 overexpression on ASCs induced on PLGA scaffolds was assessed.
ASC mineralization in dexamethasone or vitamin D3-induced ASCs correlated with both increased ERK1/2 and JNK1/2 activation. ASCs induced without dexamethasone also mineralized, with JNK1/2 signaling possibly mediating this event. No link between cortisone induction and MAPK signaling could be ascertained. ASCs treated with ERK, JNK, or p38MAPK inhibitors showed decreased osteogenic gene expression and diminished mineralization. Mineralization levels were also affected by viruses designed to inhibit or augment ERK1/2 expression and activity. Finally, ASC mineralization appeared to be a balance between the MAPK kinase activity and MKP1.
It is likely that MAPK signaling plays a significant role in ASC osteogenesis, affecting differentiation in kinase- and stage-specific manners.
促骨生成生长因子，如骨形态发生蛋白2（BMP2），在人脂肪来源干细胞（ASC）成骨过程中的应用已有详细描述。由于这些生长因子通过信号转导途径发挥作用，如丝裂原活化蛋白激酶（MAPK）级联反应，因此开展了一项关于MAPK信号与ASC成骨之间关系的研究。
在使用地塞米松或维生素D3诱导成骨的ASC中测量细胞外信号调节激酶（ERK）、应激活化蛋白激酶（JNK）和p38丝裂原活化蛋白激酶（p38MAPK）的激活情况，并将其与矿化相关联。在不使用地塞米松或使用糖皮质激素可的松的情况下也测量激活情况和矿化情况。还评估了MAPK磷酸酶MKP1的表达及其与矿化的关系。通过使用外源性抑制剂、ERK1/2的小干扰RNA敲低和腺病毒过表达来研究降低MAPK激活对矿化的影响。最后，评估ERK1/2过表达对聚乳酸-羟基乙酸共聚物（PLGA）支架上诱导的ASC的影响。
地塞米松或维生素D3诱导的ASC中的矿化与ERK1/2和JNK1/2激活增加相关。未用地塞米松诱导的ASC也发生矿化，JNK1/2信号可能介导了这一过程。无法确定可的松诱导与MAPK信号之间的联系。用ERK、JNK或p38MAPK抑制剂处理的ASC显示成骨基因表达降低且矿化减少。矿化水平也受到旨在抑制或增强ERK1/2表达和活性的病毒的影响。最后，ASC矿化似乎是MAPK激酶活性和MKP1之间的一种平衡。
MAPK信号可能在ASC成骨过程中起重要作用，以激酶特异性和阶段特异性方式影响分化。
