Ishii Kenta, Nagata Kazuki, Yamashita Niya, Yamazaki Yuki, Akimoto Yuta, Zhao Weiting, Inoue Mariko, Ito Naoto, Kasakura Kazumi, Nishiyama Chiharu
Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan.
FEBS J. 2025 Sep 4. doi: 10.1111/febs.70252.
Mucosal mast cells (MMCs) are distinguished from connective tissue mast cells (MCs) by the specific cell-surface expression of integrin CD103 (also known as integrin αE/β7; αE is encoded by Itgae) and mast cell protease 1 and 2 (Mcpt1 and Mcpt2, respectively). Although the expression of the Mcpt1 and Mcpt2 genes is cooperatively regulated by the transcription factor GATA-binding protein 2 (GATA2) and transforming growth factor beta (TGF-β) signaling in MMCs, the transcriptional mechanism of the cell-surface expression of CD103 remains unknown. We herein found that surface CD103 and Itgae mRNA levels were significantly increased by the knockdown (KD) of Gata2 in mouse bone marrow-derived MCs (BMMCs), which was accelerated by TGF-β stimulation. Since the mRNA levels of Spi1 (encoding transcription factor PU.1) were increased in Gata2 KD BMMCs, we examined the effects of PU.1 on the cell-surface expression of CD103. As expected, CD103 levels on BMMCs were significantly decreased by Spi1 KD and increased by Spi1 overexpression. Spi1 KD suppressed Itgae expression even in the presence of TGF-β in BMMCs and peritoneal MCs, whereas Gata2 KD amplified the TGF-β-induced increase in Itgae expression. The amount of PU.1 binding to the cis-element in the Itgae gene was significantly and moderately increased by Gata2 KD and TGF-β stimulation, respectively. Since PU.1 is an essential transcription factor for dendritic cells (DCs), we examined the role of PU.1 in CD103 cell-surface expression on DCs. The KD experiment using bone marrow-derived DCs (BMDCs) showed a significant decrease in CD103 levels in Spi1-siRNA-transfected BMDCs. We concluded that PU.1 affected CD103 expression on MMCs and DCs by transactivating the Itgae gene, and also that GATA2, which positively regulated the MMC-specific expression of Mcpt1 and Mcpt2, inhibited the cell-surface expression of CD103 by repressing PU.1.
黏膜肥大细胞（MMCs）与结缔组织肥大细胞（MCs）的区别在于其特异性细胞表面表达整合素CD103（也称为整合素αE/β7；αE由Itgae编码）以及肥大细胞蛋白酶1和2（分别为Mcpt1和Mcpt2）。尽管在MMCs中Mcpt1和Mcpt2基因的表达由转录因子GATA结合蛋白2（GATA2）和转化生长因子β（TGF-β）信号协同调控，但CD103细胞表面表达的转录机制仍不清楚。我们在此发现，在小鼠骨髓来源的肥大细胞（BMMCs）中，通过敲低（KD）Gata2可显著增加表面CD103和Itgae mRNA水平，而TGF-β刺激可加速这种增加。由于在Gata2 KD的BMMCs中Spi1（编码转录因子PU.1）的mRNA水平升高，我们研究了PU.1对CD103细胞表面表达的影响。正如预期的那样，Spi1 KD使BMMCs上的CD103水平显著降低，而Spi1过表达则使其升高。Spi1 KD即使在BMMCs和腹膜肥大细胞存在TGF-β的情况下也会抑制Itgae表达，而Gata2 KD则放大了TGF-β诱导的Itgae表达增加。Gata2 KD和TGF-β刺激分别使PU.1与Itgae基因顺式元件的结合量显著且适度增加。由于PU.1是树突状细胞（DCs）的必需转录因子，我们研究了PU.1在DCs上CD103细胞表面表达中的作用。使用骨髓来源的树突状细胞（BMDCs）进行的KD实验表明，转染Spi1-siRNA的BMDCs中CD103水平显著降低。我们得出结论，PU.1通过反式激活Itgae基因影响MMCs和DCs上的CD103表达，并且，对Mcpt1和Mcpt2的MMC特异性表达起正向调控作用的GATA2通过抑制PU.1来抑制CD103的细胞表面表达。
