CAS Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Immunol. 2019 Jul 4;10:1547. doi: 10.3389/fimmu.2019.01547. eCollection 2019.
The microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix-leucine zipper protein that plays a key role in cell proliferation, survival and immune defense through the direct transcriptional control of downstream genes. We have found that MITF participates in the immune response to infection in the clam . In this study, we focused on how MITF functions in immunity. First, , and were identified as the target genes of MpMITF in the clam by RNAi. EMSAs showed direct binding between the MpMITF protein and the E-box of the , and promoters. Yeast one-hybrid assays also suggested that MpMITF could activate the expression of these three downstream genes. These results demonstrated that the transcriptional expression of , and is directly regulated by MpMITF. Second, we analyzed the roles of , and in clam immunity. The mRNA expression of , and increased significantly after challenge, which implied that these genes might take part in the immune defense against challenge in clams. The purified recombinant proteins, MpPO and MpCTSK, inhibited the growth of . Additionally, the apoptosis rate of clam haemocytes rose significantly when the activity of was suppressed. These results revealed that , and are involved in the immune defense against . This study supports the idea that the MpMITF pathway plays a key role in immune defense through the direct regulation of the downstream genes , and in the clam, .
小眼畸形相关转录因子（MITF）是一种碱性螺旋-环-螺旋-亮氨酸拉链蛋白，通过对下游基因的直接转录调控，在细胞增殖、存活和免疫防御中发挥关键作用。我们发现 MITF 参与了 clam 对 的免疫反应。在这项研究中，我们重点研究了 MITF 在免疫中的作用。首先，通过 RNAi 鉴定出 clam 中的 MpMITF 的靶基因 、 和 。EMSA 显示 MpMITF 蛋白与 、 和 启动子的 E-box 之间存在直接结合。酵母单杂交实验也表明 MpMITF 可以激活这三个下游基因的表达。这些结果表明， 、 和 的转录表达受 MpMITF 的直接调控。其次，我们分析了 、 和 在 clam 免疫中的作用。在 挑战后， 、 和 的 mRNA 表达显著增加，这表明这些基因可能参与 clam 对 的免疫防御。纯化的重组蛋白 MpPO 和 MpCTSK 抑制了 的生长。此外，当抑制 的活性时，clam 血细胞的凋亡率显著升高。这些结果表明， 、 和 参与了 clam 对 的免疫防御。这项研究支持了这样一种观点，即 MpMITF 途径通过直接调节 clam 中的下游基因 、 和 ，在免疫防御中发挥关键作用。
