Chen Jinling, Wang Jingjing, Gao Xuyang, Zhu Dandan, Chen Liuting, Duan Yinong
Department of Pathogen Biology, School of Medicine, Nantong University, Nantong, China.
J Cell Mol Med. 2020 Sep;24(18):10785-10791. doi: 10.1111/jcmm.15703. Epub 2020 Jul 29.
Toxoplasma gondii excreted-secreted antigens (ESA) could result in adverse outcomes of pregnancy including abortion, stillbirth, foetal infection or teratogenesis in mice during early stage of pregnancy. Defective generation or function of regulatory T cells (Tregs) may account for those adverse pregnancy outcomes. Forkhead box p3 (Foxp3), which is the key transcriptional factor of Tregs, modulates its development and maintains inhibitory function. We previously demonstrated that ESA inhibited Foxp3 expression by attenuating transforming growth factor β RII/Smad2/Smad3/Smad4 pathway. In this study, we propose to study the role of ESA on the activity of Foxp3 promoter and explore potential mechanisms. We demonstrated that ESA suppressed Foxp3 promoter activity using dual-luciferase reporter assay. ESA functioned at -443/-96 region of Foxp3 promoter to suppress its activity using truncated fragments of Foxp3 promoter. Further analysis revealed that suppressive role of ESA on Foxp3 promoter activity is related to specificity protein 1 (SP1). Transfection of expression plasmid of pcDNA3.1-SP1 could restore the down-regulation of Foxp3 induced by ESA. In conclusion, this study provides a new mechanism by which ESA could inhibit the Foxp3 promoter activity via SP1.
弓形虫排泄-分泌抗原（ESA）可导致妊娠不良结局，包括小鼠在妊娠早期出现流产、死产、胎儿感染或致畸。调节性T细胞（Tregs）生成缺陷或功能异常可能是这些不良妊娠结局的原因。叉头框蛋白p3（Foxp3）是Tregs的关键转录因子，可调节其发育并维持抑制功能。我们之前证明，ESA通过减弱转化生长因子β RII/Smad2/Smad3/Smad4信号通路来抑制Foxp3表达。在本研究中，我们拟研究ESA对Foxp3启动子活性的作用并探索潜在机制。我们通过双荧光素酶报告基因检测证明，ESA可抑制Foxp3启动子活性。利用Foxp3启动子的截短片段，ESA在Foxp3启动子的-443/-96区域发挥作用以抑制其活性。进一步分析表明，ESA对Foxp3启动子活性的抑制作用与特异性蛋白1（SP1）有关。转染pcDNA3.1-SP1表达质粒可恢复ESA诱导的Foxp3下调。总之，本研究提供了一种新机制，即ESA可通过SP1抑制Foxp3启动子活性。
