Li Y S, Hayakawa K, Hardy R R
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
J Exp Med. 1993 Sep 1;178(3):951-60. doi: 10.1084/jem.178.3.951.
The expression of B lineage associated genes during early B cell differentiation stages is not firmly established. Using cell surface markers and multiparameter flow cytometry, bone marrow (BM) cells can be resolved into six fractions, representing sequential stages of development; i.e., pre-Pro-B, early Pro-B, late Pro-B/large Pre-B, small Pre-B, immature B, and mature B cells. Here we quantitate the levels of several B lineage associated genes in each of these fractions by RT-PCR, demonstrating different patterns of expression. We find that expression of terminal deoxynucleotidyl transferase (TdT), lambda 5, and VpreB is predominantly restricted to the Pro-B stages. Rag-1 and Rag-2 expression is also tightly regulated, and is found largely in the Pro-B through small Pre-B stages. Mb-1 is present from Pro-B throughout the pathway at high levels. Finally, Bcl-2 is expressed at high levels only at the pre-Pro-B and mature B stages, whereas it is low during all the intermediate stages. We also correlate this expression data with an analysis of the onset of Ig gene rearrangement as assessed by amplifying D-JH, VH-DJH, and VK-JK. Finally, we report differences in gene expression during B lymphopoiesis at two distinct ontogenic timings, in fetal liver and adult BM: both TdT and the precursor lymphocyte regulated myosin-like light chain are expressed at high levels in the Pro-B cell stage in bone marrow, but are absent from the corresponding fraction in fetal liver. In contrast, lambda 5, VpreB, Rag-1, and Rag-2 are expressed at comparable levels.
B细胞早期分化阶段中B谱系相关基因的表达尚未完全明确。利用细胞表面标志物和多参数流式细胞术，骨髓（BM）细胞可被分为六个部分，代表连续的发育阶段，即前原B细胞、早原B细胞、晚原B细胞/大前B细胞、小前B细胞、未成熟B细胞和成熟B细胞。在此，我们通过RT-PCR对这些部分中几种B谱系相关基因的水平进行定量，展示了不同的表达模式。我们发现末端脱氧核苷酸转移酶（TdT）、λ5和VpreB的表达主要局限于原B细胞阶段。Rag-1和Rag-2的表达也受到严格调控，主要存在于从原B细胞到小前B细胞阶段。Mb-1从原B细胞阶段开始在整个通路中高水平表达。最后, Bcl-2仅在前原B细胞和成熟B细胞阶段高水平表达，而在所有中间阶段表达水平较低。我们还将该表达数据与通过扩增D-JH、VH-DJH和VK-JK评估的Ig基因重排起始分析相关联。最后，我们报告了在胎儿肝脏和成人骨髓这两个不同个体发生时期的B淋巴细胞生成过程中基因表达的差异：TdT和前体淋巴细胞调节的肌球蛋白样轻链在骨髓中的原B细胞阶段均高水平表达，但在胎儿肝脏的相应部分中不存在。相反，λ5、VpreB、Rag-1和Rag-2在两者中的表达水平相当。
