Reactive Oxygen Species (ROS) are Induced by Kaposi's Sarcoma-Associated Herpesvirus Early During Primary Infection of Endothelial Cells to Promote Virus Entry.

Nov 2012

Bottero V, Chakraborty S, Chandran B.

Source

H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL.

Abstract

KSHV entry into human dermal microvascular endothelial cells (HMVEC-d), a natural in vivo target cell, via macropinocytosis is initiated through a multistep process involving binding of KSHV envelope glycoproteins with cell surface α3β1, αVβ3 and αVβ5 integrin molecules and tyrosine kinase EphrinA2 receptor followed by the activation of integrin-associated pre-existing signaling molecules such as FAK, Src, c-Cbl, PI3-K and Rho-GTPases. Many viruses, including KSHV, utilize cellular reactive oxygen species (ROS) for viral genomic replication and survival within host cells; however, the role of ROS on early events of viral entry and induction of signaling has not been elucidated. Here we show that KSHV induced ROS production very early during infection of HMVEC-d cells which was sustained over the observed 24 h post-infection. ROS induction was dependent on KSHV binding to the target cells since pretreatment of virus with heparin abolished ROS induction. Pretreatment of HMVEC-d cells with the antioxidant N-Acetyl-Cysteine (NAC) significantly inhibited KSHV entry and consequently gene expression without affecting virus binding. In contrast, H(2)O(2) treatment increased KSHV entry and infection. In addition, NAC inhibited KSHV infection induced translocation of αVβ3 integrin into lipid rafts, actin dependent membrane perturbations such as blebs observed during macropinocytosis and activation of EphrinA2 receptor, FAK, Src and Rac1 signal molecules. In contrast, H(2)O(2) treatment increased the activation of EphrinA2, FAK, Src and Rac1. These studies demonstrate that KSHV infection induces ROS very early during infection to amplify the signaling pathways necessary for its efficient entry via macropinocytosis in HMVEC-d cells.

PubMed