Phosphate increases bone morphogenetic protein-2 expression through cAMP-dependent protein kinase and ERK1/2 pathways in human dental pulp cells
Phosphate increases bone morphogenetic protein-2 expression through cAMP-dependent protein kinase and ERK1/2 pathways in human dental pulp cells
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DOI：
10.1016/j.bone.2011.03.675
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发表时间：
2011-06-01
期刊：
影响因子：
4.1
通讯作者：
Shimauchi, Hidetoshi
中科院分区：
文献类型：
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作者：
Tada, Hiroyuki;Nemoto, Eiji;Shimauchi, Hidetoshi
细胞外磷酸盐（Pi）通过改变基因表达和细胞功能在促进成骨细胞分化中起关键作用。重要的是，有可能使用这种知识作为一种手段，将Pi递送到局部部位，以再生与口腔相关的矿化组织。因此，我们确定了Pi调节牙髓细胞向成牙本质细胞表型分化的能力，并进一步确定这是否部分是由于骨形态发生蛋白（BMP）-2（矿化的关键调节因子）表达的增加。结果表明，Pi在mRNA和蛋白水平上增加BMP-2表达，并增加BMP-2启动子活性。信号抑制剂显示，增加BMP-2的表达依赖于cAMP/蛋白激酶A，而不是蛋白激酶C信号通路。用8-Br-cAMP（cAMP的细胞渗透性类似物）处理增强了Pi介导的BMP-2表达，但单独用8-Br-cAMP处理不增加BMP-2，这表明cAMP是必不可少的，但对于Pi介导的BMP-2表达是不够的。Pi激活ERK 1/2，并且用ERK 1/2抑制剂PD 98059处理抑制Pi介导的BMP-2增加，表明需要ERK 1/2的激活。ERK 1/2通路可能独立于cAMP依赖性信号传导而起作用，因为腺苷酸环化酶抑制剂MDL 1/2，330 A不抑制ERK 1/2响应于Pi的磷酸化。牙髓细胞表达钠依赖性Pi转运蛋白（NaPi）III型，而不表达NaPi-I型或NaPi-II型。Pi介导的BMP-2的增加在膦甲酸的存在下被抑制，膦甲酸不仅是NaPi运输的抑制剂，而且也是晶体成核的抑制剂。此外，在存在焦磷酸盐（矿化抑制剂）的情况下观察到类似的抑制作用。这些发现首次证明，Pi通过cAMP/蛋白激酶A和ERK 1/2途径调节人牙髓细胞中BMP-2的表达。(C)2011 Elsevier Inc. All rights reserved.
Extracellular phosphate (Pi) is known to play a key role in promoting osteoblastic differentiation by altering gene expression and cellular function. Importantly, it may be possible to use this knowledge as a means to deliver Pi to local sites to regenerate mineralized tissues associated with the oral cavity. Therefore, we determined the ability of Pi to regulate differentiation of pulp cells toward an odontoblast phenotype and further determined if this was in part due to an increase in the expression of bone morphogenetic protein (BMP)-2, a crucial regulator of mineralization. Results showed that Pi increased BMP-2 expression at both mRNA and protein level and BMP-2 promoter activity. Signaling inhibitors revealed that increased BMP-2 expression was dependent on cAMP/protein kinase A but not the protein kinase C signaling pathway. Treatment with 8-Br-cAMP, a cell-permeable analog of cAMP, enhanced Pi-mediated BMP-2 expression, but treatment with 8-Br-cAMP alone did not increase BMP-2, suggesting that cAMP is indispensable but not sufficient for Pi-mediated BMP-2 expression. Pi activated ERK1/2, and treatment with PD98059, an ERK1/2 inhibitor, suppressed Pi-mediated BMP-2 increase, indicating a requirement for activation of ERK1/2. ERK1/2 pathway may operate independently of cAMP-dependent signaling because MDL12,330A, an adenylate cyclase inhibitor, did not inhibit phosphorylation of ERK1/2 in response to Pi. Pulp cells expressed the sodium-dependent Pi transporter (NaPi) III type, but not NaPi-I type or NaPi-II type. Pi-mediated BMP-2 increase was inhibited in the presence of phosphonoformic acid, an inhibitor not only of NaPi transport but also of crystal nucleation. Furthermore, a similar inhibition was observed in the presence of pyrophosphate, a mineralization inhibitor. These findings demonstrate, for the first time, that Pi regulates BMP-2 expression via cAMP/protein kinase A and ERK1/2 pathways in human dental pulp cells. (C) 2011 Elsevier Inc. All rights reserved.