microRNA-7 (miR-7), a distinct miRNA family member, has been reported to be involved in the biological functions of immune cells. However, the potential role of miR-7 in the CD8⁺ T cell development remains to be elucidated. In this study, we estimated the potential effects of miR-7 overexpression in the thymic CD8⁺ SP cell development using miR-7 overexpression mice. Our results showed that compared with those in control wild type (WT) mice, the volume, weight and total cell numbers of thymus in miR-7 overexpression (OE) mice increased significantly. The absolute cell number of CD8⁺ SP cells in miR-7 OE mice increased and its ability of activation and proliferation enhanced. Futhermore, we clarified that miR-7 overexpression had an intrinsic promote role in CD8⁺ SP cell development by adoptive cell transfer assay. Mechanistically, the expression level of PIK3R1, a target of miR-7, decreased significantly in CD8⁺ SP cells of miR-7 OE mice. Moreover, the expression level of phosphorylated (p)-AKT and p-ERK changed inversely and indicating that miR-7 overexpression impaired the balance of AKE and ERK pathways. In summary, our work reveals an essential role of miR-7 in promoting CD8⁺ SP cell development through the regulation of PIK3R1 and balance of AKT and ERK pathways.

microRNA-7 (miR-7) 是一种独特的 miRNA 家族成员，据报道参与免疫细胞的生物学功能。然而，miR-7 在 CD8 ⁺ T 细胞发育中的潜在作用仍有待阐明。在这项研究中，我们使用 miR-7 过表达小鼠估计了 miR-7 过表达在胸腺 CD8 ⁺ SP 细胞发育中的潜在影响。我们的结果表明，与对照野生型（WT）小鼠相比，miR-7过表达（OE）小鼠胸腺的体积、重量和总细胞数显着增加。CD8 ⁺的绝对细胞数miR-7 OE小鼠SP细胞增多，激活增殖能力增强。此外，我们通过过继细胞转移测定阐明了 miR-7 过表达在 CD8 ⁺ SP 细胞发育中具有内在促进作用。从机制上讲，miR-7 的靶标 PIK3R1 的表达水平在miR-7 OE 小鼠的CD8 ⁺ SP 细胞中显着降低。此外，磷酸化 (p)-AKT 和p -ERK的表达水平呈反向变化，表明 miR-7 过表达损害了 AKE 和 ERK 通路的平衡。总之，我们的工作揭示了 miR-7通过调节 PIK3R1 以及平衡 AKT 和 ERK 通路在促进 CD8 ⁺ SP 细胞发育中的重要作用。