胸腺内T細胞分化に関与する上皮細胞表面分子の解析

以前我们报道了一种新的胸腺基质细胞抗原HS9，它是一种参与胸腺内T细胞发育的有效分子。HS9抗原在胸腺基质细胞上表达，尤其是在胸腺皮层，但在胸腺细胞上表达。在本研究中，我们分离并鉴定了一种新的编码HS9抗原的cDNA N14。对N14cDNA的测序分析表明，它是一个新颖的基因，与先前报道的功能分子没有明显的同源性。转染含有N14 cDNA表达载体的COS7细胞对hs9特异性单抗产生反应。Northern blot分析和原位杂交显示，一些HS9单抗阳性的组织表达n14mrna。为了研究该分子在T细胞发育中的作用，我们制造了转基因小鼠。原位杂交研究表明，该基因在胸腺皮质和髓质基质细胞上均有过表达，而在胸腺细胞上无过表达。流式细胞术分析显示，转基因小鼠成熟CD4^-CD8^+或CD4^+CD8^-胸腺细胞的百分比分别约为对照组的两倍和三倍。此外，大量CD4^+CD8^+胸腺细胞的tcri似乎与外周T细胞相当。组织学检查显示转基因小鼠皮层薄，髓质相对发达。这些数据表明N14基因在T细胞发育中的关键作用。

Previously we reported a novel thymic stromal cell antigen, HS9, as a potent molecule participating in intrathymic T cell development. HS9 antigen is expressed on thymic stromal cells especially in the cortex but out on thymocytes. In the present study, we isolated and characterized a novel cDNA,N14, encoding HS9 antigen. Sequencing analysis of N14cDNA has revealed it to be a nocel one without any significant homology to previously reported functional molecules. COS7 cells transfected with expression vectors harboring N14 cDNA became reactive with HS9-specific mAb. Northern blot analysis and in situ hybridization revealed that several tissues, which are positive for HS9 mAb, expressed N14 mRNA.In order to examine the role of this molecule in T cell development, transgenic mice were generated. In situ hybridization study showed that the transgene was significantly over-expressed on both cortical and medullar thymic stromal cells but not on thymocytes. Flowcytometric analysis showed that the percentage of mature CD4^-CD8^+ or CD4^+CD8^- thymocytes of transgenic mice were approximately twice and triple, respectively, than control littermates. Moreover, substantial CD4^+CD8^+ thymocytes appeared to be TCRhigh as comparable to peripheral T cells. Histological examination revealed that trangenic mice had thin cortex and relatively developed medulla. These data indicate the critical role of the N14 gene in T cell development.