Functional domains of Runx1 are differentially required for CD4 repression, TCRβ expression, and CD4/8 double-negative to CD4/8 double-positive transition in thymocyte development
Functional domains of Runx1 are differentially required for CD4 repression, TCRβ expression, and CD4/8 double-negative to CD4/8 double-positive transition in thymocyte development
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DOI：
10.4049/jimmunol.174.6.3526
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发表时间：
2005-03-15
影响因子：
4.4
通讯作者：
Hirai, H
中科院分区：
文献类型：
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作者：
Kawazu, M;Asai, T;Hirai, H
Runx 1（AML 1）在胸腺细胞发育中具有多种功能，包括未成熟胸腺细胞中的CD 4抑制、TCR β的表达和有效的β选择。为了确定重要的胸腺细胞发育的Runx 1的功能域，我们培养Runx 1缺陷的小鼠胎肝（FL）细胞OP 9-Delta样1小鼠基质细胞，表达Delta样I和支持胸腺细胞的体外发育，并引入Runx 1或C-末端缺失突变体Runx 1到FL细胞的逆转录病毒感染。在这个系统中，Runx 1缺陷的FL细胞未能遵循正常的胸腺细胞发育，而Runx 1的引入到细胞中足以产生胸腺细胞发育，这是难以区分的野生型FL细胞。相反，缺乏启动基因转录所必需的激活结构域的Runx 1突变体不能完全恢复胸腺细胞分化，因为它既不抑制CD 4表达，也不促进CD 4/8双阴性向CD 4/8双阳性的转变。虽然Runx 1的C-末端VWRPY基序缺陷突变体不能与转录辅阻遏物转导蛋白样分裂增强子（TLE）相互作用，但它促进了双阴性到双阳性的转变，但它不能有效地抑制CD 4的表达。这些结果表明，激活域是必不可少的Runx 1建立胸腺细胞的发展，Runx 1具有TLE依赖性和TLE独立的功能，在胸腺细胞的发展。
Runx1 (AML1) has multiple functions in thymocyte development, including CD4 repression in immature thymocytes, expression of TCRbeta,and efficient beta-selection. To determine the functional domains of Runx1 important for thymocyte development, we cultured Runx1-deficient murine fetal liver (FL) cells on OP9-Delta-like 1 murine stromal cells, which express Delta-like I and support thymocyte development in vitro, and introduced Runx1 or C-terminal-deletion mutants of Runx1 into the FL cells by retrovirus infection. In this system, Runx1-deficient FL cells failed to follow normal thymocyte development, whereas the introduction of Runx1 into the cells was sufficient to produce thymocyte development that was indistinguishable from that in wild-type FL cells. In contrast, Runx1 mutants that lacked the activation domain necessary for initiating gene transcription did not fully restore thymocyte differentiation, in that it neither repressed CD4 expression nor promoted the CD4/8 double-negative to CD4/8 double-positive transition. Although the C-terminal VWRPY motif-deficient mutant of Runx1, which cannot interact with the transcriptional corepressor Transducin-like enhancer of split (TLE), promoted the double-negative to double-positive transition, it did not efficiently repress CD4 expression. These results suggest that the activation domain is essential for Runx1 to establish thymocyte development and that Runx1 has both TLE-dependent and TLE-independent functions in thymocyte development.