Burrows Peter D, Stephan Robert P, Wang Yui-Hsi, Lassoued Kaïss, Zhang Zhixin, Cooper Max D
Division of Developmental and Clinical Immunology, University of Alabama at Birmingham, WTI 378, 1824 6th Avenue South, Birmingham, AL 35294-3300, USA.
Semin Immunol. 2002 Oct;14(5):343-9. doi: 10.1016/s1044-5323(02)00067-2.
Only a subpopulation of relatively large pre-B cells express pre-B cell receptors (preBCR) that can be seen with very sensitive immunofluorescence methods. Inefficient assembly of the multicomponent preBCR coupled with their ligand-induced endocytosis may account for the remarkably low in vivo levels of preBCR expression. Signaling initiated via the preBCR promotes cellular proliferation and RAG-1 and RAG-2 downregulation to interrupt the immunoglobulin V(D)J gene rearrangement process. Silencing of the surrogate light chain genes, VpreB and lambda5, then terminates preBCR expression to permit cell cycle exit, recombinase gene upregulation, and VJ(L) rearrangement by small pre-B cells destined to become B cells.
只有相对较大的前B细胞亚群表达前B细胞受体（preBCR），这些受体可以通过非常灵敏的免疫荧光方法检测到。多组分preBCR组装效率低下，再加上其配体诱导的内吞作用，可能是导致preBCR在体内表达水平极低的原因。通过preBCR启动的信号传导促进细胞增殖以及RAG-1和RAG-2的下调，从而中断免疫球蛋白V(D)J基因重排过程。随后，替代轻链基因VpreB和λ5的沉默会终止preBCR表达，以使细胞退出细胞周期、重组酶基因上调，并使注定要成为B细胞的小前B细胞进行VJ(L)重排。
