Emergency Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China.
Department of Microbiology and Immunology, Burns Institute, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing 100048, China.
Chin Med J (Engl). 2018 Feb 5;131(3):330-338. doi: 10.4103/0366-6999.223855.
Mitofusin-2 (MFN2), a well-known mitochondrial fusion protein, has been shown to participate in innate immunity, but its role in mediating adaptive immunity remains poorly characterized. In this study, we explored the potential role of MFN2 in mediating the immune function of T lymphocytes.
We manipulated MFN2 gene expression in Jurkat cells via lentiviral transduction of MFN2 small interfering RNA (siRNA) or full-length MFN2. After transduction, the immune response and its underlying mechanism were determined in Jurkat cells. One-way analysis of variance and Student's t-test were performed to determine the statistical significance between the groups.
Overexpression of MFN2 enhanced the immune response of T lymphocytes by upregulating Ca2+ (359.280 ± 10.130 vs. 266.940 ± 10.170, P = 0.000), calcineurin (0.513 ± 0.014 vs. 0.403 ± 0.020 nmol/L, P = 0.024), and nuclear factor of activated T cells (NFATs) activation (1.040 ± 0.086 vs. 0.700 ± 0.115, P = 0.005), whereas depletion of MFN2 impaired the immune function of T lymphocytes by downregulating Ca2+ (141.140 ± 14.670 vs. 267.060 ± 9.230, P = 0.000), calcineurin (0.054 ± 0.030 nmol/L vs. 0.404 ± 0.063 nmol/L, P = 0.000), and NFAT activation (0.500 ± 0.025 vs. 0.720 ± 0.061, P = 0.012). Furthermore, upregulated calcineurin partially reversed the negative effects of MFN2 siRNA on T cell-mediated immunity evidenced by elevations in T cell proliferation (1.120 ± 0.048 vs. 0.580 ± 0.078, P = 0.040), interleukin-2 (IL-2) production (473.300 ± 24.100 vs. 175.330 ± 12.900 pg/ml, P = 0.000), and the interferon-γ/IL-4 ratio (3.080 ± 0.156 vs. 0.953 ± 0.093, P = 0.000). Meanwhile, calcineurin activity inhibitor depleted the positive effects of overexpressed MFN2 on T cells function.
Our findings suggest that MFN2 may regulate T cell immune functions primarily through the Ca2+-calcineurin-NFAT pathway. MFN2 may represent a potential therapeutic target for T cell immune dysfunction-related diseases.
线粒体融合蛋白 2（MFN2）是一种众所周知的线粒体融合蛋白，已被证明参与先天免疫，但它在介导适应性免疫中的作用仍未得到充分描述。在这项研究中，我们探讨了 MFN2 在介导 T 淋巴细胞免疫功能中的潜在作用。
我们通过慢病毒转导 MFN2 小干扰 RNA（siRNA）或全长 MFN2 来操纵 Jurkat 细胞中的 MFN2 基因表达。转导后，在 Jurkat 细胞中确定免疫反应及其潜在机制。采用单因素方差分析和学生 t 检验来确定组间的统计学意义。
MFN2 的过表达通过上调 Ca2+（359.280 ± 10.130 比 266.940 ± 10.170，P = 0.000）、钙调神经磷酸酶（0.513 ± 0.014 比 0.403 ± 0.020 nmol/L，P = 0.024）和核因子活化 T 细胞（NFATs）的激活（1.040 ± 0.086 比 0.700 ± 0.115，P = 0.005）来增强 T 淋巴细胞的免疫反应，而 MFN2 的耗竭则通过下调 Ca2+（141.140 ± 14.670 比 267.060 ± 9.230，P = 0.000）、钙调神经磷酸酶（0.054 ± 0.030 nmol/L 比 0.404 ± 0.063 nmol/L，P = 0.000）和 NFAT 激活（0.500 ± 0.025 比 0.720 ± 0.061，P = 0.012）来削弱 T 淋巴细胞的免疫功能。此外，上调的钙调神经磷酸酶部分逆转了 MFN2 siRNA 对 T 细胞介导免疫的负向作用，表现为 T 细胞增殖（1.120 ± 0.048 比 0.580 ± 0.078，P = 0.040）、白细胞介素 2（IL-2）产生（473.300 ± 24.100 比 175.330 ± 12.900 pg/ml，P = 0.000）和干扰素-γ/IL-4 比值（3.080 ± 0.156 比 0.953 ± 0.093，P = 0.000）的升高。同时，钙调神经磷酸酶活性抑制剂耗尽了过表达 MFN2 对 T 细胞功能的正向作用。
我们的研究结果表明，MFN2 可能主要通过 Ca2+-钙调神经磷酸酶-NFAT 途径调节 T 细胞免疫功能。MFN2 可能成为与 T 细胞免疫功能障碍相关疾病的潜在治疗靶点。
