Abstract
Many viruses encode proteins that counteract the development of the interferon (IFN)-mediated antiviral state. Here, we report that interferon regulatory factor 7 (IRF7), a key mediator of type I IFN induction, is targeted for degradation by binding to the RTA immediate-early nuclear transcription factor encoded by Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8). Cotransfection with RTA blocked IRF7-mediated IFNα and IFNβ mRNA production and promoted the ubiquitination and degradation of IRF7 protein in a proteasome-dependent fashion. Addition of RTA also promoted polyubiquitination of IRF7 in an in vitro cell free assay, demonstrating that RTA itself acts as a ubiquitin E3 ligase. RTA also autoregulated its own polyubiquitination and stability, and both activities were abolished by point mutations in a Cys plus His-rich N-terminal domain. Therefore, manipulation of the stability and function of IRF7 by the KSHV RTA transcription factor provides an unexpected regulatory strategy for circumventing the innate immune defence system.
Original language | English (US) |
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Pages (from-to) | 59-70 |
Number of pages | 12 |
Journal | Immunity |
Volume | 22 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2005 |
Externally published | Yes |
ASJC Scopus subject areas
- Immunology and Allergy
- Immunology
- Infectious Diseases