The ESCRT-Related ATPase Vps4 Is Modulated by Interferon during Herpes Simplex Virus 1 Infection

Abstract

Interferons (IFNs) and autophagy are critical neuronal defenses against viral infection. IFNs alter neuronal autophagy by promoting the accumulation of IFN-dependent LC3-decorated autophagic structures, termed LC3 clusters. Here, we analyzed LC3 clusters in sensory ganglia following herpes simplex virus 1 (HSV-1) infection. In the vicinity of acutely infected neurons, antigen-negative neurons contained structures resembling accumulated autophagosomes and autolysosomes that culminated in LC3 clusters. This accumulation reflects a delayed completion of autophagy. The endosomal sorting complexes required for transport (ESCRT) machinery participates in autophagosome closure and is also required for HSV-1 replication. In this study, our results showed that HSV-1 infection in vivo and in primary neurons caused a decrease in Vps4 (a key ESCRT pathway ATPase) RNA and protein with concomitant Stat1 activation and LC3 cluster induction. We also observed that IFNs were sufficient to decrease RNA and protein levels of Vps4 in primary neurons and in other cell types. The accumulation of ubiquitin was also observed at the LC3 cluster sites. Together, our results show that IFNs modulate the ESCRT machinery in neurons in response to HSV-1 infections. IMPORTANCE Neurons rely on IFNs and autophagy as major defenses against viral infections, and HSV must overcome such defenses in order to replicate. In addition to controlling host immunity, HSV must also control host membranes in order to complete its life cycle. HSV uses the host ESCRT membrane scission machinery for viral production and transport. Here we present evidence of a new IFN-dependent mechanism used by the host to prevent ESCRT subversion by HSV. This activity also impacts the dynamics of autophagy, possibly explaining the presence of recently described LC3 clusters in the HSV-infected nervous system. The induced accumulations of ubiquitin observed in these LC3 clusters resembled those observed in certain neurodegenerative diseases, suggesting possible mechanistic parallels between these conditions.

Herpes Simplex Virus 1 Infection of Neuronal and Non-Neuronal Cells Elicits Specific Innate Immune Responses and Immune Evasion Mechanisms

“…Sensory ganglia also shows an accumulation of IFN–dependent LC3–decorated autophagic structures (LCS clusters) in result to HSV–1 infection ( 104 ). LC3 clusters appear to be associated with a delay in autophagy maturation, and resemble accumulations of autophagosomes and oversized autolysosomes in vivo ( 105 ).…”

“…Neighboring HSV–1 antigen–negative neurons also have decreased Vsp4 RNA and protein expression. It is speculated these neighboring neurons may be receiving IFN paracrine signaling, resulting in Vps4 reduction ( 105 ). Although HSV–1 downregulates IFN response and establishes lifelong latent infection in sensory neurons of the host, many studies show IFN response is critical for controlling HSV–1infection in neuronal and non–neuronal cells.…”

Synthetic Lethal Interaction between the ESCRT Paralog Enzymes VPS4A and VPS4B in Cancers Harboring Loss of Chromosome 18q or 16q

“…Integrative transcriptomic and proteomic analysis also identified a strong correlation between baseline interferon response gene expression and VPS4A dependency. Notably, the life cycle of many viruses requires the ESCRT/VPS4 pathway ( Votteler and Sundquist, 2013 ), and interferon signaling has been shown to disrupt viral maturation and budding in part because of inhibition of VPS4/ESCRT function ( Cabrera et al, 2019 ; Kuang et al, 2011 ; Pincetic et al, 2010 ). In particular, the ubiquitin-like protein interferon-stimulated gene 15 ( ISG15 ) has been reported to be upregulated by the (type I) antiviral interferon response.…”

“…ISG15 can bind the ESCRT-III subunits CHMP2A, CHMP4B, CHMP5, and CHMP6 to mask their MIT-interacting motif (MIM) domains to prevent the recruitment of VPS4 complexes ( Kuang et al, 2011 ; Pincetic et al, 2010 ). Furthermore, cellular interferon response has also been shown to halt herpes simplex virus 1 maturation in mouse neurons by downregulation of VPS4 expression and induction of CHMP4B accumulation ( Cabrera et al, 2019 ). Thus, we believe that baseline interferon response signaling in cancer cells may in part suppress VPS4/ESCRT function, thereby enhancing VPS4A dependency in the context of VPS4B loss.…”

Seeking Closure: How Do Herpesviruses Recruit the Cellular ESCRT Apparatus?

“…Among the Alphaherpesvirinae, ESCRT-III and Vps4 appear to be required for the completion of cytoplasmic envelopment by herpes simplex virus 1 (HSV-1) (49, 50) and pseudorabies virus (PRV) (50) and during HSV-1 envelopment at the INM (39). In accord with the pivotal role of Vps4 in HSV-1 envelopment, Vps4 protein and mRNA levels are both suppressed by the interferon response in HSV-1-infected mouse trigeminal ganglia (51). In contrast, the significance of the ESCRT machinery for the replication of Betaherpesvirinae is less well established.…”