Department of Medicine, University of Illinois, Chicago, IL 60612, USA.
Proc Natl Acad Sci U S A. 2013 Jun 25;110(26):10777-82. doi: 10.1073/pnas.1301764110. Epub 2013 Jun 10.
Hepatitis C virus (HCV) is a liver tropic pathogen that affects ∼170 million people worldwide and causes liver pathologies including fibrosis, cirrhosis, steatosis, iron overload, and hepatocellular carcinoma. As part of a project initially directed at understanding how HCV may disrupt cellular iron homeostasis, we found that HCV alters expression of the iron uptake receptor transferrin receptor 1 (TfR1). After further investigation, we found that TfR1 mediates HCV entry. Specifically, functional studies showed that TfR1 knockdown and antibody blocking inhibit HCV cell culture (HCVcc) infection. Blocking cell surface TfR1 also inhibited HCV pseudoparticle (HCVpp) infection, demonstrating that TfR1 acts at the level of HCV glycoprotein-dependent entry. Likewise, a TfR1 small-molecule inhibitor that causes internalization of surface TfR1 resulted in a decrease in HCVcc and HCVpp infection. In kinetic studies, TfR1 antibody blocking lost its inhibitory activity after anti-CD81 blocking, suggesting that TfR1 acts during HCV entry at a postbinding step after CD81. In contrast, viral spread assays indicated that HCV cell-to-cell spread is less dependent on TfR1. Interestingly, silencing of the TfR1 trafficking protein, a TfR-1 specific adaptor protein required for TfR1 internalization, also inhibited HCVcc infection. On the basis of these results, we conclude that TfR1 plays a role in HCV infection at the level of glycoprotein-mediated entry, acts after CD81, and possibly is involved in HCV particle internalization.
丙型肝炎病毒(HCV)是一种嗜肝病原体,影响全球约 1.7 亿人,并导致包括纤维化、肝硬化、脂肪变性、铁过载和肝细胞癌在内的肝脏病变。作为最初旨在了解 HCV 如何破坏细胞内铁稳态的项目的一部分,我们发现 HCV 改变了铁摄取受体转铁蛋白受体 1(TfR1)的表达。进一步研究发现,TfR1 介导 HCV 进入。具体来说,功能研究表明,TfR1 敲低和抗体阻断抑制 HCV 细胞培养物(HCVcc)感染。阻断细胞表面 TfR1 也抑制 HCV 假病毒(HCVpp)感染,表明 TfR1 在 HCV 糖蛋白依赖性进入水平起作用。同样,导致表面 TfR1 内化的 TfR1 小分子抑制剂导致 HCVcc 和 HCVpp 感染减少。在动力学研究中,TfR1 抗体阻断在抗 CD81 阻断后失去其抑制活性,表明 TfR1 在 HCV 进入后在 CD81 后结合步骤中起作用。相比之下,病毒传播测定表明 HCV 细胞间传播对 TfR1 的依赖性较低。有趣的是,TfR1 转运蛋白的沉默,即 TfR1 内化所需的 TfR-1 特异性衔接蛋白,也抑制了 HCVcc 感染。基于这些结果,我们得出结论,TfR1 在 HCV 感染中在糖蛋白介导的进入水平起作用,在 CD81 之后起作用,并且可能参与 HCV 颗粒内化。