Wang Qing-Hui, Nishiyama Chiharu, Nakano Nobuhiro, Shimokawa Naomi, Hara Mutsuko, Kanada Shunsuke, Ogawa Hideoki, Okumura Ko
Atopy Research Center, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Immunogenetics. 2008 Oct;60(10):557-63. doi: 10.1007/s00251-008-0318-y. Epub 2008 Jul 16.
The high-affinity receptor for immunoglobulin E (IgE), FcepsilonRI, is specifically expressed in mast cells and basophils and plays a key role in IgE-mediated allergic reactions. The transcription factor Elf-1 has been previously identified to bind to the promoter of the human FcepsilonRI alpha-chain, which is essential for the function and expression of FcepsilonRI. In the present study, Elf-1 siRNA was conducted to evaluate the effects of Elf-1 on FcepsilonRI alpha-chain expression in the primary mouse mast cells, bone marrow-derived mast cells (BMMC). Introduction of Elf-1 siRNA effectively reduced expression levels of Elf-1 mRNA and protein in BMMC. Transient reporter assay showed that the knockdown of Elf-1 by siRNA resulted in increased FcepsilonRI alpha-chain promoter activity, while overexpression of Elf-1 suppressed alpha-chain promoter activity in BMMC. Elf-1 siRNA-treated BMMC exhibited marked upregulation of FcepsilonRI alpha-chain transcription, whereas beta-chain mRNA was not affected by Elf-1 siRNA. Chromatin immunoprecipitation assay showed that the amount of transcription factor PU.1, recognizing the cis-element close to the Elf-1-site on the FcepsilonRI alpha-chain promoter, was significantly increased by introduction of Elf-1 siRNA. These results indicate that Elf-1 negatively regulates FcepsilonRI alpha-chain expression by suppressing PU.1-mediated transcription of the alpha-chain in BMMC.
免疫球蛋白E（IgE）的高亲和力受体FcepsilonRI，在肥大细胞和嗜碱性粒细胞中特异性表达，并在IgE介导的过敏反应中起关键作用。转录因子Elf-1先前已被鉴定可结合人FcepsilonRIα链的启动子，这对FcepsilonRI的功能和表达至关重要。在本研究中，进行了Elf-1 siRNA实验，以评估Elf-1对原代小鼠肥大细胞、骨髓来源的肥大细胞（BMMC）中FcepsilonRIα链表达的影响。引入Elf-1 siRNA有效降低了BMMC中Elf-1 mRNA和蛋白质的表达水平。瞬时报告基因检测显示，siRNA敲低Elf-1导致BMMC中FcepsilonRIα链启动子活性增加，而Elf-1的过表达则抑制了α链启动子活性。经Elf-1 siRNA处理的BMMC表现出FcepsilonRIα链转录的显著上调，而β链mRNA不受Elf-1 siRNA影响。染色质免疫沉淀分析表明，识别FcepsilonRIα链启动子上靠近Elf-1位点的顺式元件的转录因子PU.1的量，通过引入Elf-1 siRNA而显著增加。这些结果表明，Elf-1通过抑制BMMC中PU.1介导的α链转录来负向调节FcepsilonRIα链的表达。
