DeLuca C, Roulston A, Koromilas A, Wainberg M A, Hiscott J
Lady Davis Institute for Medical Research, Montreal, Quebec, Canada.
J Virol. 1996 Aug;70(8):5183-93. doi: 10.1128/JVI.70.8.5183-5193.1996.
Productive human immunodeficiency virus type 1 (HIV-1) infection causes sustained NF-kappaB DNA-binding activity in chronically infected monocytic cells. A direct temporal correlation exists between HIV infection and the appearance of NF-kappaB DNA-binding activity in myelomonoblastic PLB-985 cells. To examine the molecular basis of constitutive NF-kappaB DNA-binding activity in HIV1 -infected cells, we analyzed the phosphorylation and turnover of IkappaBalpha protein, the activity of the double-stranded RNA-dependent protein kinase (PKR) and the intracellular levels of NF-kappaB subunits in the PLB-985 and U937 myeloid cell models. HIV-1 infection resulted in constitutive, low-level expression of type 1 interferon (IFN) at the mRNA level. Constitutive PKR activity was also detected in HIV-1-infected cells as a result of low-level IFN production, since the addition of anti-IFN-alpha/beta antibody to the cells decreased PKR expression. Furthermore, the analysis of IkappaBalpha turnover demonstrated an increased degradation of IkappaBalpha in HIV-1-infected cells that may account for the constitutive DNA binding activity. A dramatic increase in the intracellular levels of NF-kappaB subunits c-Rel and NF-kappaB2 p100 and a moderate increase in NF-kappaB2 p52 and RelA(p65) were detected in HIV-1-infected cells, whereas NF-kappaB1 p105/p50 levels were not altered relative to the levels in uninfected cells. We suggest that HIV-1 infection of myeloid cells induces IFN production and PKR activity, which in turn contribute to enhanced IkappaBalpha phosphorylation and subsequent degradation. Nuclear translocation of NF-kappaB subunits may ultimately increase the intracellular pool of NF-kappaB/IkappaBalpha by an autoregulatory mechanism. Enhanced turnover of IkappaBalpha and the accumulation of NF-kappaB/Rel proteins may contribute to the chronically activated state of HIV-1-infected cells.
1型人类免疫缺陷病毒（HIV-1）的增殖性感染导致慢性感染的单核细胞中持续存在核因子κB（NF-κB）的DNA结合活性。在骨髓单核细胞PLB-985细胞中，HIV感染与NF-κB DNA结合活性的出现之间存在直接的时间相关性。为了研究HIV-1感染细胞中组成型NF-κB DNA结合活性的分子基础，我们分析了PLB-985和U937髓系细胞模型中IkappaBalpha蛋白的磷酸化和周转、双链RNA依赖性蛋白激酶（PKR）的活性以及NF-κB亚基的细胞内水平。HIV-1感染导致1型干扰素（IFN）在mRNA水平上组成型低水平表达。由于低水平的IFN产生，在HIV-1感染的细胞中也检测到了组成型PKR活性，因为向细胞中添加抗IFN-α/β抗体可降低PKR表达。此外，对IkappaBalpha周转的分析表明，HIV-1感染的细胞中IkappaBalpha的降解增加，这可能解释了组成型DNA结合活性。在HIV-1感染的细胞中检测到NF-κB亚基c-Rel和NF-κB2 p100的细胞内水平显著增加，NF-κB2 p52和RelA（p65）适度增加，而NF-κB1 p105/p50水平相对于未感染细胞未发生改变。我们认为，HIV-1感染髓系细胞会诱导IFN产生和PKR活性，进而导致IkappaBalpha磷酸化增强及随后的降解。NF-κB亚基的核转位最终可能通过一种自动调节机制增加细胞内NF-κB/IkappaBalpha的储备。IkappaBalpha周转的增强和NF-κB/Rel蛋白的积累可能有助于HIV-1感染细胞的慢性激活状态。
