A Virally Encoded DeSUMOylase Activity Is Required for Cytomegalovirus Reactivation from Latency

Emma L Poole,Verity G Kew,Jonathan C.H Lau,Matthew J Murray,Thomas Stamminger,John H Sinclair,Matthew B Reeves

doi:10.1016/j.celrep.2018.06.048

Emma L Poole, Verity G Kew + Show 5 more

Open Access

https://doi.org/10.1016/j.celrep.2018.06.048

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Abstract

SummaryA subset of viral genes is required for the long-term latent infection of hematopoietic cells by human cytomegalovirus (HCMV). Here, we show that a latency-associated gene product (LUNA) promotes the disruption of cellular PML bodies during latency. Mutation and inhibitor studies reveal that LUNA encodes a deSUMOylase activity responsible for this disruption. Specifically, LUNA encodes a conserved Asp-Cys-Gly motif common to all deSUMOylases. Importantly, mutation of the putative catalytic cysteine is sufficient to reverse LUNA-mediated PML dispersal and markedly reduces the efficiency of viral reactivation. The depletion of PML from cells is sufficient to rescue the reactivation of the LUNA-deficient viruses, arguing that targeting PML is an important biological role of LUNA. Finally, we demonstrate that reactivation of naturally latent HCMV is blocked by deSUMOylase inhibitors. Thus, latent HCMV primes the cellular environment for efficient reactivation via the activity of a virally encoded deSUMOylase.

Highlights

Human cytomegalovirus (HCMV) establishes a lifelong latent infection of the hematopoietic CD34+ cell population resident in the bone marrow and persists in the cells of the myelo-monocytic cell lineage
Studies from a number of laboratories point toward a model of reactivation that argues that multiple events are required for the virus to exit latency. These events involve a range of viral and cellular functions that control viral gene expression, major immediate-early (MIE) gene expression (Dupont and Reeves, 2016). Supporting this view, reactivation studies of HCMV in myeloid progenitor cells isolated from naturally latent seropositive donors have shown that cellular differentiation to macrophages or dendritic cells, chromatin regulation of viral gene expression, inflammation, and associated cellular signaling are all important for HCMV reactivation to occur (Hahn et al, 1998; Hargett and Shenk, 2010; Reeves and Compton, 2011; Reeves et al, 2005b; Reeves and Sinclair, 2013; Soderberg-Naucler et al, 1997; Zhuravskaya et al, 1997)
LUNA Expression Is Important for HCMV Reactivation from CD34+-Derived Dendritic Cells To address the function of LUNA during latent infection, we generated a virus that was mutated to prevent LUNA expression but did not disrupt the UL82 gene on the cDNA strand (LUNASHORT)

Summary

Introduction

Human cytomegalovirus (HCMV) establishes a lifelong latent infection of the hematopoietic CD34+ cell population resident in the bone marrow and persists in the cells of the myelo-monocytic cell lineage. Studies from a number of laboratories point toward a model of reactivation that argues that multiple events are required for the virus to exit latency These events involve a range of viral and cellular functions that control viral gene expression, major immediate-early (MIE) gene expression (Dupont and Reeves, 2016). Supporting this view, reactivation studies of HCMV in myeloid progenitor cells isolated from naturally latent seropositive donors have shown that cellular differentiation to macrophages or dendritic cells, chromatin regulation of viral gene expression, inflammation, and associated cellular signaling are all important for HCMV reactivation to occur (Hahn et al, 1998; Hargett and Shenk, 2010; Reeves and Compton, 2011; Reeves et al, 2005b; Reeves and Sinclair, 2013; Soderberg-Naucler et al, 1997; Zhuravskaya et al, 1997)

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