Sp1/Sp3 and PU.1 differentially regulate β5 integrin gene expression in macrophages and osteoblasts
Sp1/Sp3 and PU.1 differentially regulate β5 integrin gene expression in macrophages and osteoblasts
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DOI：
10.1074/jbc.275.12.8331
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发表时间：
2000-03-24
影响因子：
4.8
通讯作者：
Ross, FP
中科院分区：
文献类型：
--
作者：
Feng, X;Teitelbaum, SL;Ross, FP
小鼠破骨细胞前体和成骨细胞表达整合素α(V)β(5)，其在细胞表面的出现由β(5)而不是α(V)亚单位控制，在这里，我们证明了β(5)启动子的173个碱基对在巨噬细胞(破骨细胞前体)样细胞和成骨细胞中介导了β(5)的基础转录。DNase I足迹揭示了173碱基对区域内的四个区域(FP1-FP4)，受到巨噬细胞核提取物的保护。相反，成骨细胞核提取液仅保护巨噬细胞和成骨细胞核提取液结合Sp1和Sp3。FP4不结合成骨细胞蛋白，但结合来自巨噬细胞的PU1。转染研究表明，在MC3T3-E1(成骨细胞样)和J774(巨噬细胞样)细胞系中，FP1和FP2 Sp1/SP3位点起增强子作用，而FP3 Sp1/SP3位点起沉默作用。在J774细胞中，Fp2 Sp1/SP3位点的突变使启动子活性完全丧失，而在MC3T3-E1细胞中仅部分降低。最后，我们证明了PU1在J774细胞中作为β(5)沉默因子，而在MC3T3-E1细胞中不起作用。因此，三个Sp1/SP3位点调节巨噬细胞和成骨细胞中的β(5)基因表达，每个元件都表现出细胞类型和/或激活抑制特异性。
Murine osteoclast precursors and osteoblasts express the integrin alpha(v)beta(5), the appearance of which on the cell surface is controlled by the beta(5), and not the alpha(v), subunit, Here, we show that a 173-base pair proximal region of the beta(5) promoter mediates beta(5) basal transcription in macrophage (osteoclast precursor)-like and osteoblastlike cells. DNase I footprinting reveal four regions (FP1-FP4) within the 173-base pair region, protected by macrophage nuclear extracts. In contrast, osteoblast nuclear extracts protect only FP1, FP2, and FP3, FP1, FP2, and FP3 bind Sp1 and Sp3 from both macrophage and osteoblast nuclear extracts. FP4 does not bind osteoblast proteins but binds PU.1 from macrophages, Transfection studies show that FP1 and FP2 Sp1/Sp3 sites act as enhancers in both MC3T3-E1 (osteoblast-like) and J774 (macrophage-like) cell lines, whereas the FP3 Sp1/Sp3 site serves as a silencer. Mutation of the FP2 Sp1/Sp3 site totally abolishes promoter activity in J774 cells, with only partial reduction in MC3T3-E1 cells, Finally, we demonstrate that PU.1 acts as a beta(5) silencer in J774 cells but plays no role in MC3T3-E1 cells. Thus, three Sp1/Sp3 sites regulate beta(5) gene expression in macrophages and osteoblast-like cells, with each element exhibiting cell-type and/or activation-suppression specificity.