Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Japan.
FEBS Open Bio. 2020 Jun;10(6):1115-1121. doi: 10.1002/2211-5463.12861. Epub 2020 Apr 30.
C-C chemokine receptor type 7 (CCR7) is expressed on naïve T cells, B cells, and activated dendritic cells (DCs). We previously demonstrated that the transcription factor PU.1/Spi1 positively regulates the expression of CCR7 in DCs. In the present study, we investigated the role of PU.1 in CCR7 expression in T cells. To confirm whether PU.1 is involved in the expression of CCR7, we conducted a ChIP assay in various T cells purified from splenocytes and thymocytes and found that PU.1 binds to the Ccr7 promoter-proximal region in spleen naïve CD4 T cells, but not in thymocytes. Small interfering RNA-mediated PU.1 knockdown resulted in decreased CCR7 expression in spleen naïve CD4 T cells. Compared to naïve CD4 T cells, Spi1 and Ccr7 mRNA levels decreased in Th1 and Th2 cells, in which PU.1 did not bind to the Ccr7 promoter, suggesting that CCR7 expression decreases due to the dissociation of PU.1 from the Ccr7 promoter during the development of effector T cells from naïve T cells. Collectively, we concluded that CCR7 expression level correlates with the binding level of PU.1 to the Ccr7 promoter and PU.1 acts as a transcriptional activator of the Ccr7 gene in naïve CD4 T cells.
C-C 趋化因子受体 7（CCR7）在幼稚 T 细胞、B 细胞和活化的树突状细胞（DC）上表达。我们之前证明，转录因子 PU.1/Spi1 正向调节 DC 中 CCR7 的表达。在本研究中，我们研究了 PU.1 在 T 细胞中 CCR7 表达中的作用。为了确认 PU.1 是否参与 CCR7 的表达，我们在从脾细胞和胸腺细胞纯化的各种 T 细胞中进行了 ChIP 测定，发现 PU.1 在脾幼稚 CD4 T 细胞中结合 Ccr7 启动子近端区域，但在胸腺细胞中不结合。小干扰 RNA 介导的 PU.1 敲低导致脾幼稚 CD4 T 细胞中 CCR7 表达降低。与幼稚 CD4 T 细胞相比，Th1 和 Th2 细胞中的 Spi1 和 Ccr7 mRNA 水平降低，其中 PU.1 未结合 Ccr7 启动子，这表明在幼稚 T 细胞向效应 T 细胞的发育过程中，由于 PU.1 从 Ccr7 启动子解离，CCR7 表达降低。总的来说，我们得出结论，CCR7 表达水平与 PU.1 与 Ccr7 启动子的结合水平相关，并且 PU.1 在幼稚 CD4 T 细胞中作为 Ccr7 基因的转录激活剂发挥作用。
