Human papillomavirus (HPV) type 18 E7 protein is a short-lived steroid-inducible phosphoprotein in HPV-transformed cell lines.
Human papillomavirus (HPV) type 18 E7 protein is a short-lived steroid-inducible phosphoprotein in HPV-transformed cell lines.
复制标题
DOI：
10.1099/0022-1317-75-7-1647
复制
发表时间：
1994-07
期刊：
影响因子：
--
通讯作者：
Linda A. Selvey;Linda A. Dunn;R. Tindle;D. Park;Ian H. Frazer
中科院分区：
文献类型：
--
作者：
Linda A. Selvey;Linda A. Dunn;R. Tindle;D. Park;Ian H. Frazer
我们使用捕获ELISA来定量人乳头瘤病毒18型（HPV-18）的E7蛋白。在表达低水平免疫反应性E7蛋白（iE7）的HeLa细胞中，iE7的平均半衰期为13.5 min。在表达较高水平E7的HPV-18 E7重组杆状病毒（E7 rec BV）感染的Sf 21细胞中，iE7的半衰期要长得多（90 min和> 24 h，使用两种不同的E7 rec BV）。对于表达HPV-18 E7的两种转化的人宫颈细胞系，将细胞暴露于氢化可的松导致E7蛋白的稳态水平增加两倍：在孕酮、雌激素或睾酮中没有观察到类似的效果。iE7的半衰期不受氢化可的松或孕酮暴露的影响。区分Ser 33-磷酸化的E7与在该残基处未磷酸化的E7的免疫测定（Ser 33去磷酸-E7），表明在HeLa和Sf 21细胞中，大部分E7被磷酸化：两种E7在HeLa细胞中的半衰期相似，但在Sf 21细胞中，Ser 33去磷酸-E7的半衰期（90 min）比Ser 33磷酸-E7的半衰期（> 24 h）短得多。具有致瘤潜力的HeLa-成纤维细胞融合细胞系（CGL-1）具有与无致瘤潜力的类似融合细胞系（CGL-4）相似的脱磷酸-E7与总E7的比率（0.06）（0.03）。我们的结论是，E7是一个不稳定的磷蛋白，E7蛋白在真核细胞中的表达和稳态水平可能会受到细胞的激素环境的影响。
We used a capture ELISA to quantify the E7 protein of human papillomavirus type 18 (HPV-18). In HeLa cells, which express low levels of immunoreactive E7 protein (iE7), iE7 had a mean half-life of 13.5 min. In HPV-18 E7 recombinant baculovirus (E7rec BV)-infected Sf21 cells, which express higher levels of E7, the half-life of iE7 was much longer (90 min and > 24 h, with two different E7rec BVs). For two transformed human cervical cell lines expressing HPV-18 E7, exposure of the cells to hydrocortisone resulted in a twofold increase in steady-state levels of the E7 protein: no similar effect was observed with progesterone, oestrogen or testosterone. The half-life of iE7 was unaltered by hydrocortisone or progesterone exposure. An immunoassay which distinguished Ser33-phosphorylated E7 from E7 not phosphorylated at this residue (Ser33dephospho-E7), showed that in HeLa and Sf21 cells the majority of E7 was phosphorylated: the half-life of both species of E7 was similar in HeLa cells, but the half-life of Ser33dephospho-E7 was much shorter (90 min) in Sf21 cells than that of Ser33phospho-E7 (> 24 h). A HeLa-fibroblast fusion cell line with tumorigenic potential (CGL-1) had a similar ratio of dephospho-E7 to total E7 (0.06), as a similar fusion cell line (CGL-4) with no tumorigenic potential (0.03). We conclude that E7 is a labile phosphoprotein, and that the expression and steady-state level of the E7 protein in eukaryotic cells may be influenced by the hormonal environment of the cells.