ZAPS is a potent stimulator of signaling mediated by the RNA helicase RIG-I during antiviral responses

262

337

The zinc-finger antiviral protein (ZAP) was originally identified as a host factor that inhibits the replication of Moloney murine leukemia virus. Here we report that ZAP inhibits HIV-1 infection by promoting the degradation of specific viral mRNAs. Overexpression of ZAP rendered cells resistant to HIV-1 infection in a ZAP expression level-dependent manner, whereas depletion of endogenous ZAP enhanced HIV-1 infection. Both human and rat ZAP inhibited the propagation of replication-competent HIV-1. ZAP specifically targeted the multiply spliced but not unspliced or singly spliced HIV-1 mRNAs for degradation. We provide evidence indicating that ZAP selectively recruits cellular poly(A)-specific ribonuclease (PARN) to shorten the poly(A) tail of target viral mRNA and recruits the RNA exosome to degrade the RNA body from the 39 end. In addition, ZAP recruits cellular decapping complex through its cofactor RNA helicase p72 to initiate degradation of the target viral mRNA from the 59 end. Depletion of each of these mRNA degradation enzymes reduced ZAP's activity. Our results indicate that ZAP inhibits HIV-1 by recruiting both the 59 and 39 mRNA degradation machinery to specifically promote the degradation of multiply spliced HIV-1 mRNAs.retrovirus | host restriction factor | RNA degradation

Section: Discussionmentioning

confidence: 99%

Zinc-finger antiviral protein inhibits HIV-1 infection by selectively targeting multiply spliced viral mRNAs for degradation

Zhu

Chen

et al. 2011

262

337

“…A recent study showed that ZAP positively regulated RIG-I signaling during RNA virus infection in a human cell line (28). Therefore, we examined the involvement of ZAP in the RIG-I-dependent type I IFN response in primary mouse cells.…”

Section: Zap Does Not Regulate the Rig-i-dependent Type I Ifn Responsmentioning

confidence: 99%

Zinc-finger antiviral protein mediates retinoic acid inducible gene I–like receptor-independent antiviral response to murine leukemia virus

Lee

Komano

Saitoh

et al. 2013

When host cells are infected by an RNA virus, pattern-recognition receptors (PRRs) recognize the viral RNA and induce the antiviral innate immunity. Toll-like receptor 7 (TLR7) detects the genomic RNA of incoming murine leukemia virus (MLV) in endosomes and mediates the antiviral response. However, the RNA-sensing PRR that recognizes the MLV in the cytosol is not fully understood.Here, we definitively demonstrate that zinc-finger antiviral protein (ZAP) acts as a cytosolic RNA sensor, inducing the degradation of the MLV transcripts by the exosome, an RNA degradation system, on RNA granules. Although the retinoic acid inducible gene I (RIG-I)-like receptors (RLRs) RIG-I and melanoma differentiation-associated protein 5 detect various RNA viruses in the cytosol and induce the type I IFN-dependent antiviral response, RLR loss does not alter the replication efficiency of MLV. In sharp contrast, the loss of ZAP greatly enhances the replication efficiency of MLV. ZAP localizes to RNA granules, where the processing-body and stress-granule proteins assemble. ZAP induces the recruitment of the MLV transcripts and exosome components to the RNA granules. The CCCH-type zincfinger domains of ZAP, which are RNA-binding motifs, mediate its localization to RNA granules and MLV transcripts degradation by the exosome. Although ZAP was known as a regulator of RIG-I signaling in a human cell line, ZAP deficiency does not affect the RIG-I-dependent production of type I IFN in mouse cells. Thus, ZAP is a unique member of the cytosolic RNA-sensing PRR family that targets and eliminates intracellular RNA viruses independently of TLR and RLR family members.host defense | retrovirus | ZC3HAV1

“…Human ZAPL exhibits stronger antiviral activity than hZAPS against MuLV expression and Semliki forest virus infection (35) whereas both isoforms prevent HIV-1 infection (27). The ZAP isoforms are relatively broadly expressed in human tissues (35), but the mRNA expression of hZAPS is markedly increased by IFNα treatment (36). hZAPS is also more active than hZAPL in enhancing RIG-Idependent signaling in response to 5′-triphosphate-modified RNA, suggesting that regulation of ZAP activity can enhance or even amplify IFN responses (36).…”

mentioning

confidence: 99%

“…The ZAP isoforms are relatively broadly expressed in human tissues (35), but the mRNA expression of hZAPS is markedly increased by IFNα treatment (36). hZAPS is also more active than hZAPL in enhancing RIG-Idependent signaling in response to 5′-triphosphate-modified RNA, suggesting that regulation of ZAP activity can enhance or even amplify IFN responses (36). In addition, ZAPS and ZAPL are both polyADP ribosylated and have been implicated in stabilization of mRNA during cellular stress (37).…”

mentioning

confidence: 99%

Prenylome profiling reveals S-farnesylation is crucial for membrane targeting and antiviral activity of ZAP long-isoform

Charron

MacDonald

et al. 2013

115

159

S-prenylation is an important lipid modification that targets proteins to membranes for cell signaling and vesicle trafficking in eukaryotes. As S-prenylated proteins are often key effectors for oncogenesis, congenital disorders, and microbial pathogenesis, robust proteomic methods are still needed to biochemically characterize these lipidated proteins in specific cell types and disease states. Here, we report that bioorthogonal proteomics of macrophages with an improved alkyne-isoprenoid chemical reporter enables large-scale profiling of prenylated proteins, as well as the discovery of unannotated lipidated proteins such as isoform-specific S-farnesylation of zinc-finger antiviral protein (ZAP). Notably, S-farnesylation was crucial for targeting the long-isoform of ZAP (ZAPL/PARP-13.1/zc3hav1) to endolysosomes and enhancing the antiviral activity of this immune effector. These studies demonstrate the utility of isoprenoid chemical reporters for proteomic analysis of prenylated proteins and reveal a role for protein prenylation in host defense against viral infections.