ZAP’s stress granule localization is correlated with its antiviral activity and induced by virus replication

Abstract

Cellular antiviral programs encode molecules capable of targeting multiple steps in the virus lifecycle. Zinc-finger antiviral protein (ZAP) is a central and general regulator of antiviral activity that targets pathogen mRNA stability and translation. ZAP is diffusely cytoplasmic, but upon infection ZAP is targeted to particular cytoplasmic structures, termed stress granules (SGs). However, it remains unclear if ZAP’s antiviral activity correlates with SG localization, and what molecular cues are required to induce this localization event. Here, we use Sindbis virus (SINV) as a model infection and find that ZAP’s localization to SGs can be transient. Sometimes no apparent viral infection follows ZAP SG localization but ZAP SG localization always precedes accumulation of SINV non-structural protein, suggesting virus replication processes trigger SG formation and ZAP recruitment. Data from single-molecule RNA FISH corroborates this finding as the majority of cells with ZAP localization in SGs contain low levels of viral RNA. Furthermore, ZAP recruitment to SGs occurred in ZAP-expressing cells when co-cultured with cells replicating full-length SINV, but not when co-cultured with cells replicating a SINV replicon. ZAP recruitment to SGs is functionally important as a panel of alanine ZAP mutants indicate that the anti-SINV activity is correlated with ZAP’s ability to localize to SGs. As ZAP is a central component of the cellular antiviral programs, these data provide further evidence that SGs are an important cytoplasmic antiviral hub. These findings provide insight into how antiviral components are regulated upon virus infection to inhibit virus spread.

Dance with the Devil: Stress Granules and Signaling in Antiviral Responses

“…ZAP mutants revealed that recruitment to SGs correlates with ZAP antiviral activity. However, this study also indicated that ZAP interaction partners are important for antiviral function [265]. TRIM25, as an example, was shown to be an essential co-factor for the ability of ZAP to block SINV translation [359].…”

Interferon-Gamma Modulation of the Local T Cell Response to Alphavirus Encephalomyelitis

“…Rsad2-encoded viperin can impair budding of enveloped viruses [47][48][49] and alphavirus and flavivirus replication and assembly [50][51][52][53]. Zc3hav1 encodes zinc-finger antiviral protein (ZAP) or poly(ADP-ribose) polymerase-13 (PARP13), an RNA-binding protein that recruits RNA decay factors to degrade viral RNA and inhibit viral RNA translation [54][55][56][57][58]. However, the specific role for these ISGs in IFN-γ-mediated virus clearance from neurons will require further study.…”

The impact of PARPs and ADP-ribosylation on inflammation and host–pathogen interactions

“…However, ZAP sensitivity of a panel of alphaviruses does not correlate with the CG dinucleotide content found in their genome or individual viral genes, suggesting that the CG dinucleotide motif is not the only determinant for ZAP recognition . The localization of ZAP to stress granules also appears to be functionally important for its antiviral activity against alphaviruses, as ZAP mutants that do not localize to SGs are unable to block SINV replication (Law et al 2019). In vivo, Zap knockout (Zc3hav1 −/− ) mice showed enhanced replication of SINV in 10-d-old mice as expected (Kozaki et al 2015).…”