Volpe C P, Lundgren A, Aints A, Mohamed A J, Jaakkola P, Christensson B, Gahrton G, Jalkanen M, Smith C I, Dilber M S
Center for Biotechnology, Department of Biosciences, Karolinska Institute, NOVUM, Huddinge, Sweden.
Am J Hematol. 2001 May;67(1):20-6. doi: 10.1002/ajh.1071.
Syndecan-1 (CD138) is a cell membrane proteoglycan that binds extracellular matrix components and various growth factors. The role of syndecan-1 in the control of cell growth and morphology has been illustrated by its altered expression in hematological malignancies such as multiple myeloma as well as some solid tumors. It has been reported that the expression of syndecan-1 in cells of the B lineage is developmentally regulated such that pre-B cells and plasma cells express syndecan-1 while mature B cells do not. Thus, we investigated whether the proximal promoter region of the murine syndecan-1 promoter was able to confer the observed on-off-on expression of syndecan-1 in cells of the B lineage as they develop from pre-B cells to plasma cells. Experiments carried out using deletion mutants of the proximal promoter cloned upstream of the CAT reporter gene transfected into murine cell lines, representing the above stages of B-cell development, such as BA/F3 (pro-B cell), 70Z/3 (pre-B cell), 2PK3 (late mature B cell), and MPC-11 (plasma cell), showed detectable levels of CAT expression. The WEHI-231 (mature B cell) cell lines did not show detectable levels of CAT reporter activity. The strong levels of expression were observed with a fragment of the proximal promoter spanning the region from -365 to -95 (from the translation start point). However, Northern analysis of RNA obtained from the five murine B-cell lines, representing various stages of B-cell development, showed that the 70Z/3, MPC-11 but not BA/F3, and 2PK3 cells expressed detectable levels of syndecan-1 mRNA. By FACS analysis, using a rat anti mouse syndecan-1 antibody, syndecan-1 expression on the cell surface was found to correlate with the observed mRNA expression patterns in these cell lines. Our results indicate that the proximal promoter of the murine syndecan-1 promoter is not sufficient for the observed developmental pattern of syndecan expression in B cells.
Syndecan-1（CD138）是一种细胞膜蛋白聚糖，可结合细胞外基质成分和多种生长因子。Syndecan-1在控制细胞生长和形态方面的作用已通过其在血液系统恶性肿瘤（如多发性骨髓瘤）以及一些实体瘤中的表达改变得以体现。据报道，B淋巴细胞系细胞中Syndecan-1的表达受发育调控，前B细胞和浆细胞表达Syndecan-1，而成熟B细胞则不表达。因此，我们研究了小鼠Syndecan-1启动子的近端启动子区域是否能够赋予在B淋巴细胞系细胞从前B细胞发育为浆细胞过程中观察到的Syndecan-1的开-关-开表达模式。使用克隆到CAT报告基因上游的近端启动子缺失突变体进行的实验，转染到代表B细胞发育上述阶段的小鼠细胞系中，如BA/F3（前B细胞）、70Z/3（前B细胞）、2PK3（晚期成熟B细胞）和MPC-11（浆细胞），显示出可检测到的CAT表达水平。WEHI-231（成熟B细胞）细胞系未显示出可检测到的CAT报告基因活性水平。在跨越从-365至-95区域（从翻译起始点起）的近端启动子片段中观察到强表达水平。然而，对代表B细胞发育不同阶段的五种小鼠B细胞系获得的RNA进行Northern分析表明，70Z/3、MPC-11细胞表达可检测到水平的Syndecan-1 mRNA，但BA/F3和2PK3细胞不表达。通过流式细胞术分析，使用大鼠抗小鼠Syndecan-1抗体，发现细胞表面的Syndecan-1表达与这些细胞系中观察到的mRNA表达模式相关。我们的结果表明，小鼠Syndecan-1启动子的近端启动子不足以实现B细胞中观察到的Syndecan表达发育模式。
