title: H11/HSPB8 Restricts HIV-2 Vpx to Restore the Anti-Viral Activity of SAMHD1.
abstract: Virus-host interactions play vital roles in viral replication and virus-induced pathogenesis. Viruses rely entirely upon host cells to reproduce progeny viruses; however, host factors positively or negatively regulate virus replication by interacting with viral proteins. The elucidation of virus-host protein interaction not only provides a better understanding of the molecular mechanisms by which host cells combat viral infections, but also facilitates the development of new anti-viral therapeutics. Identification of relevant host factors requires techniques that enable comprehensive characterization of virus-host protein interactions. In this study, we developed a proteomic approach to systematically identify human protein kinases that interact potently with viral proteins. For this purpose, we synthesized 412 full-length human protein kinases using the wheat germ cell-free protein synthesis system, and screened them for their association with a virus protein using the amplified luminescent proximity homogenous assay (AlphaScreen). Using this system, we attempted to discover a robust anti-viral host restriction mechanism targeting virus protein X (Vpx) of HIV-2. The screen identified H11/HSPB8 as a Vpx-binding protein that negatively regulates the stability and function of Vpx. Indeed, overexpression of H11/HSPB8 promoted the degradation of Vpx via the ubiquitin-proteasome pathway and inhibited its interaction with SAMHD1, a host restriction factor responsible for blocking replication of HIV. Conversely, targeted knockdown of H11/HSPB8 in human trophoblast cells, which ordinarily express high levels of this protein, restored the expression and function of Vpx, making the cells highly susceptible to viral replication. These results demonstrate that our proteomic approach represents a powerful tool for revealing virus-host interaction not yet identified by conventional methods. Furthermore, we showed that H11/HSPB8 could be a potential host regulatory factor that may prevent placental infection of HIV-2 during pregnancy.
authors.affiliation: Department of Microbiology, School of Medicine, Yokohama City University Yokohama, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kudoh
authors.affiliation: Department of Microbiology, School of Medicine, Yokohama City University Yokohama, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Miyakawa
authors.affiliation: Department of Microbiology, School of Medicine, Yokohama City University Yokohama, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Matsunaga
authors.affiliation: Kawasaki City Health and Safety Research Center Kanagawa, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Matsushima
authors.affiliation: Department of Regenerative and Infectious Pathology, Hamamatsu University School of Medicine Hamamatsu, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Kosugi
authors.affiliation: Infectious Disease Surveillance Center, National Institute of Infectious Diseases Tokyo, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kimura
authors.affiliation: Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hayakawa
authors.affiliation: Proteo-Science Center, Ehime University Matsuyama, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sawasaki
authors.affiliation: Department of Microbiology, School of Medicine, Yokohama City University Yokohama, Japan.
authors.forename: Akihide
authors.initials: A
authors.lastname: Ryo
keywords: AlphaScreen; H11; HIV-2; Vpx; virus–host interaction; wheat germ cell-free protein synthesis