Zaller D M, Eckhardt L A
Proc Natl Acad Sci U S A. 1985 Aug;82(15):5088-92. doi: 10.1073/pnas.82.15.5088.
A transcriptional enhancer has recently been identified between the variable and constant region coding segments of an assembled immunoglobulin heavy-chain gene. This enhancer is required for efficient expression of such genes when transfected into myeloma cells. A class switch rearrangement in the mouse myeloma cell line 9.9.2.1 has resulted in deletion of this enhancer, and yet this cell line continues to produce heavy chains at a high level. Cell line 9.9.2.1 is a gamma 2a-producing class-switch variant derived from the gamma 2b-producing myeloma cell line, MPC11. We demonstrate that despite the high level of heavy-chain production in 9.9.2.1, the cloned 9.9.2.1 heavy-chain gene is not expressed efficiently when transfected into myeloma cells. Efficient expression after transfection can be obtained only if the deleted enhancer is reinserted into the gene. The implication of this finding for the role of this enhancer in establishing and/or maintaining immunoglobulin heavy-chain gene expression is discussed.
最近在一个组装好的免疫球蛋白重链基因的可变区和恒定区编码片段之间发现了一个转录增强子。当转染到骨髓瘤细胞中时，这种基因的高效表达需要该增强子。小鼠骨髓瘤细胞系9.9.2.1中的一次类别转换重排导致了这个增强子的缺失，但该细胞系仍继续高水平产生重链。细胞系9.9.2.1是一个产生γ2a的类别转换变体，源自产生γ2b的骨髓瘤细胞系MPC11。我们证明，尽管9.9.2.1中重链产量很高，但克隆的9.9.2.1重链基因转染到骨髓瘤细胞中时并不能高效表达。只有将缺失的增强子重新插入该基因，转染后才能获得高效表达。本文讨论了这一发现对于该增强子在建立和/或维持免疫球蛋白重链基因表达中的作用的意义。
