Smith Emma M K, Gisler Ramiro, Sigvardsson Mikael
Laboratory of Cellular Differentiation, Department of Stem Cell Biology, Lund University, Lund, Sweden.
J Immunol. 2002 Jul 1;169(1):261-70. doi: 10.4049/jimmunol.169.1.261.
The early B cell factor (EBF) is a transcription factor shown crucial for the development of B lymphocytes. The protein is expressed from the earliest stages of B cell development until the mature B cell stage, but the control elements responsible for the regulation of the gene are unknown. In this study, we report of the identification of a promoter region flanking the EBF gene. Several transcription start sites were identified by primer extension analysis in a region approximately 3.1 kb from the predicted ATG. Transient transfections revealed that this region was able to stimulate transcription of a reporter gene in B lymphoid and to a lesser extent, myeloid cells, but not in a pre-T cell line. The promoter was also able to functionally interact with E47, suggesting that the EBF gene may be a direct target for activation by E-proteins. In addition, functional binding of EBF to its own promoter was confirmed by EMSA and transfection assays indicating that the EBF protein may be involved in an autoregulatory loop. Finally, a tissue-restricted factor was able to bind an upstream regulatory region in B-lineage cells, further supporting the idea that the cloned promoter participates in the regulation of stage and lineage specific expression of the EBF gene.
早期B细胞因子（EBF）是一种转录因子，对B淋巴细胞的发育至关重要。该蛋白从B细胞发育的最早阶段一直表达至成熟B细胞阶段，但负责该基因调控的控制元件尚不清楚。在本研究中，我们报告了EBF基因侧翼启动子区域的鉴定。通过引物延伸分析在距预测的ATG约3.1 kb的区域内鉴定出了几个转录起始位点。瞬时转染显示该区域能够刺激B淋巴细胞中报告基因的转录，在较小程度上也能刺激髓样细胞中的转录，但在T前体细胞系中则不能。该启动子还能够与E47进行功能相互作用，这表明EBF基因可能是E蛋白激活的直接靶点。此外，通过电泳迁移率变动分析（EMSA）和转染实验证实了EBF与其自身启动子的功能性结合，表明EBF蛋白可能参与了一个自我调节环。最后，一种组织限制性因子能够结合B系细胞中的上游调控区域，进一步支持了克隆的启动子参与EBF基因阶段和谱系特异性表达调控的观点。
