Langerak A W, Wolvers-Tettero I L, van Gastel-Mol E J, Oud M E, van Dongen J J
Department of Immunology, Erasmus University Rotterdam/University Hospital Rotterdam, The Netherlands.
Blood. 2001 Oct 15;98(8):2456-65. doi: 10.1182/blood.v98.8.2456.
T-cell receptor (TCR) gene rearrangements are mediated via V(D)J recombination, which is strictly regulated during lymphoid differentiation, most probably through the action of specific transcription factors. Investigated was whether cotransfection of RAG1 and RAG2 genes in combination with lymphoid transcription factors can induce TCR gene rearrangements in nonlymphoid human cells. Transfection experiments showed that basic helix-loop-helix transcription factors E2A and HEB induce rearrangements in the TCRD locus (Ddelta2-Ddelta3 and Vdelta2-Ddelta3) and TCRG locus (psi Vgamma7-Jgamma2.3 and Vgamma8-Jgamma2.3). Analysis of these rearrangements and their circular excision products revealed some peculiar characteristics. The Vdelta2-Ddelta3 rearrangements were formed by direct coupling without intermediate Ddelta2 gene segment usage, and most Ddelta2-Ddelta3 recombinations occurred via direct coupling of the respective upstream and downstream recombination signal sequences (RSSs) with deletion of the Ddelta2 and Ddelta3 coding sequences. Subsequently, the E2A/HEB-induced TCR gene recombination patterns were compared with those in early thymocytes and acute lymphoblastic leukemias of T- and B-lineage origin, and it was found that the TCR rearrangements in the transfectants were early (immature) and not necessarily T-lineage specific. Apparently, some parts of the TCRD (Vdelta2-Ddelta region) and TCRG genes are accessible for recombination not only in T cells, but also in early B-cells and even in nonlymphoid cells if the appropriate transcription factors are present. The transfection system described here appeared to be useful for studying the accessibility of immunoglobulin and TCR genes for V(D)J recombination, but might also be applied to study the induction of RSS-mediated chromosome aberrations.
T 细胞受体（TCR）基因重排是通过 V(D)J 重组介导的，在淋巴细胞分化过程中受到严格调控，很可能是通过特定转录因子的作用。研究了 RAG1 和 RAG2 基因与淋巴细胞转录因子共转染是否能在非淋巴细胞的人类细胞中诱导 TCR 基因重排。转染实验表明，碱性螺旋-环-螺旋转录因子 E2A 和 HEB 可诱导 TCRD 基因座（Dδ2-Dδ3 和 Vδ2-Dδ3）和 TCRG 基因座（ψVγ7-Jγ2.3 和 Vγ8-Jγ2.3）发生重排。对这些重排及其环状切除产物的分析揭示了一些独特的特征。Vδ2-Dδ3 重排是通过直接连接形成的，未使用中间的 Dδ2 基因片段，大多数 Dδ2-Dδ3 重组是通过各自上游和下游重组信号序列（RSS）的直接连接发生的，同时删除了 Dδ2 和 Dδ3 的编码序列。随后，将 E2A/HEB 诱导的 TCR 基因重组模式与 T 系和 B 系起源的早期胸腺细胞及急性淋巴细胞白血病中的模式进行了比较，发现转染细胞中的 TCR 重排是早期（不成熟）的，且不一定具有 T 系特异性。显然，如果存在适当的转录因子，TCRD（Vδ2-Dδ 区域）和 TCRG 基因的某些部分不仅在 T 细胞中可用于重组，在早期 B 细胞甚至非淋巴细胞中也可用于重组。这里描述的转染系统似乎有助于研究免疫球蛋白和 TCR 基因对于 V(D)J 重组的可及性，但也可能用于研究 RSS 介导的染色体畸变的诱导。
