MCP-1通过p38和ERK/MAPK途径在人单核细胞中诱导Stat3丝氨酸磷酸化

MCP-1 Inducing Stat3 Serine Phosphorylation via p38 and ERK Pathways in Human Monocytes

为了探讨人单核细胞中,人单核细胞趋化因子1(monocyte chemoattractant protein-1,MCP-1)诱导信号转导激活转录因子3(signal transducers and activators of transcription 3,Stat3)磷酸化以及导致磷酸化的丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)信号通路途径在其中的作用,首先采用针对Stat3 705位酪氨酸和727位丝氨酸特异性抗体进行磷酸化时间和剂量的检测,发现MCP-1仅导致Stat3丝氨酸磷酸化并且呈剂量和时间依赖性,而酪氨酸并没有磷酸化.在此基础上,采用不同时间点的方法对MAPK途径成员细胞外信号调节激酶(extracellular signal-regulated kinase,ERK)、p38、JNK进行检测,发现MCP-1在人单核细胞中仅诱导ERK、p38活化并呈时间依赖性,而不能诱导激活JNK途径.为了确证ERK、p38途径在人单核细胞中参与MCP-1诱导的Stat3丝氨酸磷酸化,采用ERK、p38途径活化的小分子抑制化合物不同浓度处理单核细胞,对Stat3丝氨酸磷酸化检测发现,MCP-1通过ERK、p38两条途径参与Stat3丝氨酸磷酸化.这些结果表明,MCP-1在人单核细胞中仅诱导Stat3丝氨酸磷酸化而不是酪氨酸磷酸化;MAPK成员中ERK、p38两条途径均参与MCP-1诱导的Stat3丝氨酸磷酸化,而JNK途径没有活化参与Stat3丝氨酸磷酸化.

Monocyte chemoattactant protein-1 （MCP-1） plays a crucial role in the recruitment of monocytes associated with several inflammatory disease and malignancies. In order to investigate Stat3 phosphorylation induced by MCP-1 in human monocytes, we used anti-phospho-STAT3 （Tyr 705） and （Ser 727） antibodies in Western blot analysis to identify that 727 serine phosphorylation of Stat3 was induced in monocytes only. Serine phosphorylation of Star3 induced by MCP-1 was in time and dose dependent fashion. Moreover, in the MAPK pathway involved in Star3 serine phosphorylation investigation, we observed that MCP-1 could trigger p38 and ERK （extracellular signal-regulated kinase） pathways but not JNK pathway in time dependent fashion. A few inhibitors of p38 and ERK activation used to block the serine phosphorylation of Star3 induced by MCP-1 identified that both p38 and ERK pathways involved in serine phosphorylation of Star3 in human monocytes. Taken together, MCP-1 can only trigger Stat3 serine phosphorylation and not tyrosine phosphorylation via p38 and ERK pathways in human monocytes.