Direction de la Recherche Fondamentale, Institut de Biologie François Jacob, Service de Recherches en Hémato-Immunologie, Hôpital Saint-Louis, Commissariat à l'Energie Atomique et aux Energies Alternatives, Paris, France.
Institut de Recherche Saint-Louis, Université de Paris, UMR976 HIPI, Hôpital Saint-Louis, Université Paris-Diderot, Paris, France.
Immunology. 2019 Oct;158(2):121-135. doi: 10.1111/imm.13099. Epub 2019 Aug 19.
The Autoimmune Regulator (Aire) protein coordinates the negative selection of developing thymocytes by inducing the expression of hundreds of tissue-specific antigens within the thymic medulla, which is also a primary site of the expression of the immune checkpoint HLA-G molecule. Considering the immunomodulatory properties of Aire and HLA-G, and considering that the role of the constitutive thymus expression of HLA-G has not been elucidated, we studied the effect of AIRE cDNA transfection on HLA-G expression in 4D6 thymic cells and in the HLA-G-positive JEG-3 choriocarcinoma cells. Aire promoted the transactivation of HLA-G gene by increasing the overall transcription, inducing the transcription of at least G1 and G2/G4 isoforms, and incrementing the occurrence and distribution of intracellular HLA-G protein solely in 4D6 thymic cells. Luciferase-based assays and chromatin immunoprecipitation experiments performed in 4D6 cells revealed that Aire targeted at least two regions within the 5'-untranslated regulatory region (5'-URR) extending 1·4 kb from the first ATG initiation codon. The interaction occurs independently of three putative Aire-binding sites. These results indicate that the Aire-induced upregulation of HLA-G in thymic cells is likely to act through the interaction of Aire with specific HLA-G 5'-URR DNA-binding factors. Such a multimeric transcriptional complex might operate in the thymus during the process of promiscuous gene expression.
自身免疫调节因子 (Aire) 蛋白通过诱导胸腺髓质中数百种组织特异性抗原的表达来协调未成熟胸腺细胞的阴性选择，而这也是免疫检查点 HLA-G 分子表达的主要部位。鉴于 Aire 和 HLA-G 的免疫调节特性，以及考虑到 HLA-G 在固有胸腺表达的作用尚未阐明，我们研究了 AIRE cDNA 转染对 4D6 胸腺细胞和 HLA-G 阳性 JEG-3 绒毛膜癌细胞中 HLA-G 表达的影响。Aire 通过增加整体转录来促进 HLA-G 基因的反式激活，诱导至少 G1 和 G2/G4 异构体的转录，并仅在 4D6 胸腺细胞中增加细胞内 HLA-G 蛋白的发生和分布。在 4D6 细胞中进行的基于荧光素酶的测定和染色质免疫沉淀实验表明，Aire 靶向至少两个位于起始密码子 ATG 前的 5'-非翻译调节区 (5'-URR) 的区域，该区域延伸 1.4kb。这种相互作用独立于三个假定的 Aire 结合位点发生。这些结果表明，Aire 诱导胸腺细胞中 HLA-G 的上调可能是通过 Aire 与特定 HLA-G 5'-URR DNA 结合因子相互作用而发生的。这种多聚体转录复合物可能在胸腺中参与杂乱基因表达的过程中发挥作用。
