REGULATION OF RAG-1 AND CD69 EXPRESSION IN THE THYMUS DURING POSITIVE AND NEGATIVE SELECTION
REGULATION OF RAG-1 AND CD69 EXPRESSION IN THE THYMUS DURING POSITIVE AND NEGATIVE SELECTION
复制标题
DOI：
10.1002/eji.1830240122
复制
发表时间：
1994-01-01
影响因子：
5.4
通讯作者：
PIRCHER, H
中科院分区：
文献类型：
--
作者：
BRANDLE, D;MULLER, S;PIRCHER, H
在胸腺选择过程中，T细胞受体（TPR）与主要组织相容性复合体（MHC）分子的成功相互作用下调了胸腺皮质细胞中重组激活基因(RAG)-1和-2的表达，从而阻止了内源性TCR α链基因的进一步重排（Borgulya， P., Kishi， H., Uematsu，Y.）。von Boehmer， H., Cell. 1992。69: 529 - 537;Brandle， D, Muller， C, Rulicke，T。，亨格特纳，H.和皮尔彻，H., n.c.。学会科学。美国1992年。89: 9529 - 9533)。为了解决rag1活性下调是否代表一个不可逆过程的问题，我们阻断了胸腺细胞与胸腺基质细胞的TPR-MHC相互作用。首先，向表达病毒特异性MHC I类（H-2D(b)）限制性TCR的转基因（Tg）小鼠注射抗d -b或抗cd8单克隆抗体，并通过胸腺切片原位杂交检测RAG-1的表达。结果表明，在给药后24小时内，皮质胸腺细胞上调了rag1的表达。其次，将TCR Tg小鼠的未成熟胸腺细胞从胸腺微环境中释放出来，在体外单细胞悬液中培养14 h。与新鲜分离的胸腺细胞相比，培养细胞中rag1 mRNA的数量增加了6倍。此外，我们发现携带非选择性MHC分子（11-2(d)）的TCR转基因小鼠的未成熟胸腺细胞在抗原诱导的TPR参与后下调了RAG-1的表达。细胞荧光分析进一步显示，在阳性和阴性选择过程中，未成熟胸腺细胞表面CD69的表达与RAG-1的表达呈负相关。
Successful interaction of the T cell receptor (TPR) with major histocompatibility complex (MHC) molecules during thymic selection down-regulates the expression of the recombination activating genes (RAG)-1 and -2 in cortical thymocytes and thereby prevents further endogenous TCR alpha-chain gene rearrangements (Borgulya, P., Kishi, H., Uematsu,Y. and von Boehmer, H., Cell. 1992. 69: 529-537; Brandle, D., Muller, C., Rulicke,T., Hengartner, H. and Pircher, H., Proc. Natl. Acad. Sci. USA 1992. 89: 9529-9533). To address the question whether down-regulation of RAG-1 activity represents an irreversible process we have blocked TPR-MHC interactions of thymocytes with thymic stromal cells. Firstly, transgenic (Tg) mice expressing a virus-specific MHC class I (H-2D(b))-restricted TCR were injected with anti-D-b or anti-CD8 monoclonal antibodies and RAG-1 expression was examined by in situ hybridization on thymus sections. The results show that cortical thymocytes up-regulated RAG-1 expression within 24h after antibody administration. Secondly, immature thymocytes from TCR Tg mice were released from the thymic microenvironment and cultured in vitro for 14 h in single-cell suspension. The amount of RAG-1 mRNA was increased sixfold in cultured cells when compared to freshly isolated thymocytes. In addition, we show that immature thymocytes from TCR transgenic mice bearing non-selective MHC molecules (11-2(d)) down-regulated RAG-1 expression after antigen-induced TPR engagement. Cytofluorometric analysis further revealed that surface expression of CD69 on immature thymocytes inversely correlated with RAG-1 expression during positive and negative selection processes.