Bui Matthew, Myers Julie E, Whittaker Gary R
Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
Virus Res. 2002 Mar 20;84(1-2):37-44. doi: 10.1016/s0168-1702(01)00413-0.
Influenza virus nucleoprotein (NP) plays a major role in the nucleus during virus replication, and is a mediator of viral ribonucleoprotein nuclear import during entry. NP is localized primarily in the nucleus, but can undergo nucleo-cytoplasmic shuttling in heterokaryons (Whittaker et al., 1996a. J. Virol. 70, p. 2743). We have studied NP localization using a stable cell line (3PNP-4) that expresses NP. Intracellular localization of NP was markedly affected by the density of the cell monolayer. It was nuclear in cells grown in sparse culture, but cytoplasmic in dense culture. In phorbol ester-stimulated cells NP was cytoplasmic, but relocalized to the nucleus after treatment with a protein kinase inhibitor. Cell density and phosphorylation-dependent localization of NP appeared to be independent of cell type. Our data suggest that a phosphorylation event is needed either for nuclear export, or to regulate retention of NP in the nucleus, and that regulation may be mediated by kinases activated by cell-cell contact.
流感病毒核蛋白（NP）在病毒复制过程中于细胞核内发挥主要作用，并且在病毒进入时是病毒核糖核蛋白核输入的介质。NP主要定位于细胞核，但在异核体中可进行核质穿梭（惠特克等人，1996年a。《病毒学杂志》70卷，第2743页）。我们使用表达NP的稳定细胞系（3PNP - 4）研究了NP的定位。NP的细胞内定位明显受细胞单层密度的影响。在稀疏培养的细胞中它位于细胞核内，但在致密培养时位于细胞质中。在佛波酯刺激的细胞中，NP位于细胞质中，但在用蛋白激酶抑制剂处理后重新定位于细胞核。NP的细胞密度和磷酸化依赖性定位似乎与细胞类型无关。我们的数据表明，核输出或调节NP在细胞核内的保留需要磷酸化事件，并且这种调节可能由细胞间接触激活的激酶介导。
