Poster abstracts
Poster number 30 submitted by Zixi Long
Identification and Characterization of HTLV-1 Gag-interacting protein YBX1 in the viral lifecycle
Zixi Long (Molecular, Cellular and Developmental Biology Program, Center for Retrovirus Research, and Center for RNA Biology, Ohio State University, Columbus, OH), Yu-Ci Syu (Molecular, Cellular and Developmental Biology Program, Center for Retrovirus Research, and Center for RNA Biology, Ohio State University, Columbus, OH), Amanda Panfil (Department of Veterinary Biosciences, Center for Retrovirus Research Ohio State University, Columbus, OH), Karin Musier-Forsyth (Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH)
Abstract:
Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus that induces adult T-cell leukemia/lymphoma (ATLL) in approximately 5% of the infected population. In contrast to HIV-1, effective antiretroviral therapies to treat HTLV-1 infected individuals are lacking. In the late stage of the HTLV-1 lifecycle, the viral group-specific antigen (Gag) protein packages the viral genomic RNA into immature viral particles at the host cell plasma membrane prior to budding. The role of host proteins in this process is unclear. In this work, affinity tagging/purification-mass spectrometry (AP-MS) was performed to identify HTLV-1 Gag-interacting partners. Briefly, Gag encoding a twin-strep tag was expressed in HEK293T cells, pulled down by streptavidin. and co-purified proteins were identified by MS. One of the top 10 hits obtained was Y-box-binding protein 1 (YBX1), a ubiquitous transcription factor with many identified DNA-, RNA-, and protein-interacting partners. YBX1 activates multiple genes involved in cell proliferation. In breast cancer cells, YBX1 stabilizes multiple oncogene transcripts including AKT Serine/Threonine Kinase 1 via binding to their 3′ UTR, which promotes oncogenesis and cell proliferation. YBX1 has also been shown to bind to HTLV-1 Tax and promote viral RNA transcription. Co-immunoprecipitation studies validated YBX1 binding to HTLV-1 Gag in cell lysates and preliminary studies showed that this interaction is RNA-independent. Domain mapping experiments revealed that HTLV-1 Gag interacts with YBX1 through the nucleocapsid (NC) zinc finger domains, and that the C-terminal domain 2 of YBX1 is important for the interaction. Analysis of HTLV-1 virions purified by sucrose cushion and opti-prep density gradient indicated that YBX1 is packaged into HTLV-1 virions. Ongoing work is aimed at studying the effect of YBX1 knockdown on viral infectivity and viral RNA packaging. This study reinforces the role of YBX1 in the HTLV-1 lifecycle and supports its potential as a therapeutic target to treat HTLV-1 infection and ATLL patients.
Keywords: HTLV-1, Y-box-binding protein 1 , Group-specific antigen