Donohoe M E, Blomberg B B
Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101, USA.
J Immunol. 1997 Feb 15;158(4):1681-91.
The 14.1 surrogate light chain protein is expressed on human pre-B lymphocytes in association with Vpre-B and the mu Ig heavy chain to form the pre-B receptor. The 14.1 chain has also been called the lambda (lambda)-like (LL) protein and is homologous to murine lambda5. The 14.1(IGLL1) gene is expressed in a lineage- and stage-restricted manner. To understand the molecular mechanism of the 14.1 gene tissue- and stage-specific expression, we analyzed the 5'-flanking region and characterized the promoter for this gene. In this report, we identify two DNase I-hypersensitive sites located at 2.6 kilobases (HSS 1) and 0.2 kilobases (HSS 1) upstream of 14.1 exon 1. These hypersensitive sites are present in pre-B lymphocyte cell lines, but absent in mature B and T cell lines. We have used RNase protection analysis to localize the 5' major transcriptional start site and rapid amplification of 5' cDNA ends to identify multiple start sites within the TATA-less, GC-rich 14.1 promoter. The region encompassing HSS 2 was analyzed for promoter activity. Transfection of cell lines with a series of truncated segments of the 5' flanking region linked to the luciferase reporter gene revealed that the 14.1 promoter is lineage- and stage-specific, and we localized this activity to positions +150 to +227 relative to the 5' major transcriptional start site.
14.1替代轻链蛋白与Vpre - B和μIg重链一起在人前B淋巴细胞上表达，形成前B细胞受体。14.1链也被称为类λ（λ）蛋白，与小鼠λ5同源。14.1（IGLL1）基因以谱系和阶段受限的方式表达。为了解14.1基因组织和阶段特异性表达的分子机制，我们分析了其5'侧翼区域并对该基因的启动子进行了表征。在本报告中，我们鉴定出位于14.1外显子1上游2.6千碱基（HSS 1）和0.2千碱基（HSS 2）处的两个DNase I超敏位点。这些超敏位点存在于前B淋巴细胞系中，但在成熟B和T细胞系中不存在。我们使用核糖核酸酶保护分析来定位5'主要转录起始位点，并通过5' cDNA末端的快速扩增来鉴定无TATA、富含GC的14.1启动子内的多个起始位点。对包含HSS 2的区域进行了启动子活性分析。用与荧光素酶报告基因相连的5'侧翼区域的一系列截短片段转染细胞系，结果表明14.1启动子具有谱系和阶段特异性，我们将这种活性定位到相对于5'主要转录起始位点的 +150至 +227位置。
