Li Jian, Li Yang, Cao Yinyin, Yuan Meifen, Gao Zhengfeng, Guo Xuemei, Zhu Fenhua, Wang Yunfeng, Xu Jin
Center Clinical Laboratory, Children's Hospital of Fudan University, Shanghai 201102, China.
Laboratory Medicine, Kunming Medical University, Kunming 650101, China.
Arch Biochem Biophys. 2014 Dec 15;564:184-8. doi: 10.1016/j.abb.2014.10.004. Epub 2014 Oct 14.
CD4(+) T cell polarization plays a critical role in a number of immune disorders; the pathogenesis is unclear. Chromobox homolog 7 (Cbx7) is involved in the gene transcription of several cell types. This study aims to investigate the mechanism by which Cbx7 modulates the CD4(+) T cell polarization. Expression of Cbx7 was assessed by quantitative RT-PCR and Western blotting. Apoptosis of CD4(+) T cell was analyzed by flow cytometry. The FasL promoter methylation was evaluated by the methylation specific PCR. The results showed that CD4(+) CD25(-) T cells express Cbx7 that was increased significantly after activation by exposing to anti-CD3/CD28 Ab, but suppressed by exposing to specific antigens. More apoptotic cells were detected in CD4(+) T cells with the Cbx7 gene knockdown. Exposure to insulin-like growth factor-1 up regulated the expression of Cbx7 in CD4(+) T cells. After antigen-specific TCR activation, Cbx7-deficient CD4(+) T cells expressed more FasL and showed the FasL gene promoter hyper demethylation than wild CD4(+) T cells. In addition, CD4(+) T cells with overexpression of Cbx7 showed lower levels of FasL gene promoter demethylation. We conclude that CD4(+) T cells express Cbx7; the latter prevents FasL expression and the activation-induced CD4(+) T cell apoptosis.
CD4(+) T细胞极化在多种免疫紊乱中起关键作用；其发病机制尚不清楚。染色体盒同源物7（Cbx7）参与多种细胞类型的基因转录。本研究旨在探讨Cbx7调节CD4(+) T细胞极化的机制。通过定量逆转录聚合酶链反应（qRT-PCR）和蛋白质免疫印迹法评估Cbx7的表达。采用流式细胞术分析CD4(+) T细胞的凋亡情况。通过甲基化特异性聚合酶链反应评估FasL启动子甲基化。结果显示，CD4(+) CD25(-) T细胞表达Cbx7，在暴露于抗CD3/CD28抗体激活后显著增加，但在暴露于特异性抗原后受到抑制。在Cbx7基因敲低的CD4(+) T细胞中检测到更多凋亡细胞。暴露于胰岛素样生长因子-1可上调CD4(+) T细胞中Cbx7的表达。抗原特异性TCR激活后，Cbx7缺陷型CD4(+) T细胞比野生型CD4(+) T细胞表达更多FasL，且FasL基因启动子超甲基化。此外，Cbx7过表达的CD4(+) T细胞显示FasL基因启动子去甲基化水平较低。我们得出结论，CD4(+) T细胞表达Cbx7；后者可防止FasL表达及激活诱导的CD4(+) T细胞凋亡。
