Ossendorp F, Jacobs H, van der Horst G, de Vries E, Berns A, Borst J
Division of Immunology, The Netherlands Cancer Institute, Amsterdam.
J Immunol. 1992 Jun 15;148(12):3714-22.
A TCR-beta gene lacking V domain sequences (delta V-TCR-beta) was inserted into the germline of mice. Expression of the transgene inhibited endogenous TCR-beta, but not TCR-alpha gene rearrangement and expression. The mutated TCR-beta gene affected alpha beta T cell development: the common thymocyte pool was normal in cell number, with cells expressing CD4 and CD8, but the mature, "CD3bright" population expressing either CD4 or CD8 molecules was reduced by 90%. To help understand these effects on TCR-beta gene rearrangement and T cell development, biosynthesis of the delta V-TCR-beta protein was analyzed in a tumor cell line derived from a transgenic mouse. Despite absence of the V domain, the delta V-TCR-beta chain paired with endogenous TCR-alpha chains and assembled with CD3 gamma, -delta, -epsilon, and -zeta components in the endoplasmatic reticulum, followed by transport through the Golgi complex to the plasma membrane. Therefore, assembly of the complex, and even cell surface expression, may be relevant for allelic exclusion of the TCR-beta gene. In the common thymocyte population, the CD3 components, endogenous TCR-alpha, and the delta V-TCR-beta gene product were expressed at the RNA level, but endogenous TCR-beta was not. The TCR-alpha delta beta/CD3 complex was present at the cell surface at low levels and was functional in terms of anti-CD3-induced Ca2+ mobilization. The observed arrest of alpha beta T cell development at the CD4+8+ thymocyte stage indicates that ligand recognition by the TCR, with contribution of the beta-chain V domain, is not required for transition of CD4-8- thymocytes to the CD4+8+ phenotype, but necessary for entry into the "single positive," CD3bright differentiation stage.
将一个缺乏V结构域序列的TCR-β基因（δV-TCR-β）插入小鼠种系。转基因的表达抑制了内源性TCR-β，但不影响TCR-α基因的重排和表达。突变的TCR-β基因影响αβT细胞的发育：普通胸腺细胞池的细胞数量正常，细胞表达CD4和CD8，但表达CD4或CD8分子的成熟“CD3bright”群体减少了90%。为了帮助理解这些对TCR-β基因重排和T细胞发育的影响，在源自转基因小鼠的肿瘤细胞系中分析了δV-TCR-β蛋白的生物合成。尽管缺乏V结构域，δV-TCR-β链仍与内源性TCR-α链配对，并在内质网中与CD3γ、-δ、-ε和-ζ组分组装，随后通过高尔基体转运至质膜。因此，复合物的组装甚至细胞表面表达可能与TCR-β基因的等位基因排斥有关。在普通胸腺细胞群体中，CD3组分、内源性TCR-α和δV-TCR-β基因产物在RNA水平表达，但内源性TCR-β不表达。TCR-αδβ/CD3复合物在细胞表面低水平存在，并且在抗CD3诱导的Ca2+动员方面具有功能。观察到αβT细胞发育在CD4+8+胸腺细胞阶段停滞，这表明TCR对配体的识别（β链V结构域起作用）对于CD4-8-胸腺细胞向CD4+8+表型的转变不是必需的，但对于进入“单阳性”、CD3bright分化阶段是必需的。
