Oliviero S, Morrone G, Cortese R
EMBL, Heidelberg, FRG.
EMBO J. 1987 Jul;6(7):1905-12. doi: 10.1002/j.1460-2075.1987.tb02450.x.
Haptoglobin is a plasma protein scarcely present in fetal but abundant in adult serum, where it is present at a concentration of approximately 150 mg/100 ml. In this paper we show by run-on experiments that the haptoglobin (Hp) gene is actively transcribed in adult but not in fetal liver nuclei. Studies with established cell lines indicate that the Hp gene is expressed in the hepatoma cells HepG2 but not in the hepatoma cell line Hep3B nor in HeLa cells. Plasmids carrying various segments of the 5' flanking region of the Hp gene fused to the chloramphenicol acetyl transferase (CAT) gene direct CAT transcription when introduced into HepG2 but are inactive in Hep3B and in HeLa cells, thus behaving like the resident chromosomal Hp gene. Deletion analysis defines a region, upstream to the transcription initiation site, essential for cell-specific expression. The Hp gene is induced in Hep3B cells by treatment with supernatant from LPS-stimulated monocytes (SMS), in a manner mimicking the acute phase reaction. We characterize the DNA segment necessary and sufficient for cell-specific expression of the Hp-CAT constructions in HepG2 and show that the same segment is also sufficient for acute phase induction in Hep3B.
触珠蛋白是一种血浆蛋白，在胎儿中几乎不存在，但在成人血清中含量丰富，其浓度约为150mg/100ml。在本文中，我们通过连续转录实验表明，触珠蛋白（Hp）基因在成人肝细胞核中活跃转录，而在胎儿肝细胞核中不转录。对已建立的细胞系的研究表明，Hp基因在肝癌细胞HepG2中表达，但在肝癌细胞系Hep3B和HeLa细胞中不表达。携带Hp基因5'侧翼区不同片段并与氯霉素乙酰转移酶（CAT）基因融合的质粒，导入HepG2时可指导CAT转录，但在Hep3B和HeLa细胞中无活性，其表现与常驻染色体Hp基因相似。缺失分析确定了转录起始位点上游的一个区域，该区域对细胞特异性表达至关重要。通过用脂多糖刺激的单核细胞（SMS）上清液处理，Hp基因在Hep3B细胞中被诱导，其方式模拟急性期反应。我们鉴定了在HepG2中Hp-CAT构建体细胞特异性表达所必需且充分的DNA片段，并表明该片段对Hep3B中的急性期诱导也足够。
