Abstract：
Thymic epithelial cells (TECs) are crucial to the ability of the thymus to generate T cells for the adaptive immune system in vertebrates. However, no in vitro system for studying TEC function exists. Overexpressing the transcription factor FOXN1 initiates transdifferentiation of fibroblasts into TEC-like cells (iTECs) that support T-cell differentiation in culture or after transplant. In this study, we have characterized iTEC programming at the cellular and molecular level in mouse to determine how it proceeds, and have identified mechanisms that can be targeted for improving this process. These data show that iTEC programming consists of discrete gene expression changes that differ early and late in the process, and that iTECs upregulate markers of both cortical and medullary TEC (cTEC and mTEC) lineages. We demonstrate that promoting proliferation enhances iTEC generation, and that Notch inhibition allows the induction of mTEC differentiation. Finally, we show that MHCII expression is the major difference between iTECs and fetal TECs. MHCII expression was improved by co-culturing iTECs with fetal double-positive T-cells. This study supports future efforts to improve iTEC generation for both research and translational uses.
摘要：
胸腺上皮细胞（TECs）是脊椎动物胸腺产生适应性免疫系统T细胞的能力的关键功能成分。然而,不存在用于研究TEC功能的体外系统。过表达转录因子FOXN1启动成纤维细胞转分化为TEC样细胞(iTECs),其支持培养中或移植后的T细胞分化。在这项研究中,我们在细胞和分子水平对iTEC编程进行了表征,以确定其如何进行,并确定了可用于改善该过程的靶向机制.这些数据表明，iTEC编程由过程中早期和晚期不同的离散基因表达变化组成，iTECs上调皮质和髓质TEC（cTEC和mTEC）谱系的标志物。我们证明了促进增殖增强了iTEC的产生，并且Notch抑制允许诱导mTEC分化。最后,我们表明MHCII表达是iTECs和胎儿TECs之间的主要差异。通过将iTECs与胎儿双阳性T细胞共培养来改善MHCII表达。这项研究支持未来为研究和翻译用途改进iTEC生成的努力。
