A lymphocyte-specific enhancer in the mouse immunoglobulin κ gene
A lymphocyte-specific enhancer in the mouse immunoglobulin κ gene
复制标题
小鼠免疫球蛋白κ基因中的无母细胞淋巴特异性增强子
作者：
D. Picard;W. Schaffner
在淋巴细胞分化为抗体产生细胞的过程中，免疫球蛋白 κ 可变区基因通过重排而被转录激活，将其与 κ 恒定区 (Cκ) 区基因连接起来，该基因在体细胞重排之前就已经转录1,2。据推测，κ 轻链基因大内含子内存在转录增强子元件可以解释这种激活模式，并得到 DNase I3-5 和限制性内切酶优先进入的染色质区域证据的支持。该 DNA 区域包含一段约 130 个碱基对 (bp) 的片段，该片段在小鼠、兔和人之间高度保守。此外，在 κ 基因中检测不到转录本，该基因在大内含子内被截短。最近，在免疫球蛋白重链基因 8-10 的连接区域下游发现了淋巴细胞特异性增强子。我们现在展示了小鼠大 κ 基因内含子内功能相似的增强子的直接证据。然而，它的活性不如重链基因增强子。相反，没有发现增强子与克隆的 λI 轻链基因相关。
During differentiation of lymphocytes into antibody-producing cells, an immunoglobulin κ variable-region gene is transcriptionally activated by rearrangement linking it to a κ constant (Cκ) region gene which is already transcribed prior to somatic rearrangement1,2. The presence of a transcriptional enhancer element within the large intron of the κ light-chain gene has been postulated to explain this mode of activation, supported by evidence of a chromatin region which is preferentially accessible to DNase I3–5 and restriction enzymes5. This DNA region contains a segment of about 130 base pairs (bp) which is strongly conserved between mouse, rabbit and man6. Moreover, no transcripts are detectable from a κ gene, which is truncated within the large intron7. Recently, a lymphocyte-specific enhancer has been identified downstream of the joining region in immunoglobulin heavy-chain genes8–10. We now show direct evidence for a functionally similar enhancer within the large κ gene intron of the mouse. It is, however, less active than the heavy-chain gene enhancer. In contrast, no enhancer was found to be associated with a cloned λI light-chain gene.