Alt F W, Yancopoulos G D, Blackwell T K, Wood C, Thomas E, Boss M, Coffman R, Rosenberg N, Tonegawa S, Baltimore D
EMBO J. 1984 Jun;3(6):1209-19. doi: 10.1002/j.1460-2075.1984.tb01955.x.
The immunoglobulin heavy chain variable region is encoded as three separate libraries of elements in germ-line DNA: VH, D and JH. To examine the order and regulation of their joining, we have developed assays that distinguish their various combinations and have used the assays to study tumor cell analogs of B-lymphoid cells as well as normal B-lymphoid cells. Abelson murine leukemia virus (A-MuLV) transformed fetal liver cells - the most primitive B-lymphoid cell analog available for analysis - generally had DJH rearrangements at both JH loci. These lines continued DNA rearrangement in culture, in most cases by joining a VH gene segment to an existing DJH complex with the concomitant deletion of intervening DNA sequences. None of these lines or their progeny showed evidence of VHD or DD rearrangements. Heavy chain-producing tumor lines, representing more mature stages of the B-cell pathway, and normal B-lymphocytes had either two VHDJH rearrangements or a VHDJH plus a DJH rearrangement at their two heavy chain loci; they also showed no evidence of VHD or DD rearrangements. These results support an ordered mechanism of variable gene assembly during B-cell differentiation in which D-to-JH rearrangements generally occur first and on both chromosomes followed by VH-to-DJH rearrangements, with both types of joining processes occurring by intrachromosomal deletion. The high percentage of JH alleles remaining in the DJH configuration in heavy chain-producing lines and, especially, in normal B-lymphocytes supports a regulated mechanism of heavy chain allelic exclusion in which a VHDJH rearrangement, if productive, prevents an additional VH-to-DJH rearrangement.
免疫球蛋白重链可变区在种系DNA中被编码为三个独立的元件文库：VH、D和JH。为了研究它们连接的顺序和调控，我们开发了能够区分其各种组合的检测方法，并使用这些方法来研究B淋巴细胞的肿瘤细胞类似物以及正常B淋巴细胞。艾贝尔逊鼠白血病病毒（A-MuLV）转化的胎肝细胞——可用于分析的最原始的B淋巴细胞类似物——通常在两个JH基因座处都有DJH重排。这些细胞系在培养中继续进行DNA重排，在大多数情况下是通过将一个VH基因片段连接到现有的DJH复合体上，并伴随中间DNA序列的缺失。这些细胞系及其后代均未显示VHD或DD重排的证据。代表B细胞分化更成熟阶段的重链产生肿瘤细胞系和正常B淋巴细胞在其两个重链基因座处要么有两个VHDJH重排，要么有一个VHDJH加上一个DJH重排；它们也没有显示VHD或DD重排的证据。这些结果支持了B细胞分化过程中可变基因组装的有序机制，其中D-to-JH重排通常首先在两条染色体上发生，随后是VH-to-DJH重排，两种连接过程均通过染色体内缺失发生。在重链产生细胞系中，尤其是在正常B淋巴细胞中，DJH构型中剩余的JH等位基因比例很高，这支持了重链等位基因排斥的调控机制，即如果VHDJH重排是有功能的，则会阻止额外的VH-to-DJH重排。
