A G1-like state allows HIV-1 to bypass SAMHD1 restriction in macrophages.

Petra Mlcochova,Stuart J Neil,Simon Yona,Sarah A Watters,Mahdad Noursadeghi,Christiana Georgiou,Rob Am De Bruin,Gina M Lenzi,Ravindra K Gupta,Greg J Towers,Baek Kim,Asim Khwaja,Jan Rehwinkel,Matthew C Gage,Cosetta Bertoli,Alexandra Chittka,Katherine A Sutherland

doi:10.15252/embj.201696025

Abstract

An unresolved question is how HIV‐1 achieves efficient replication in terminally differentiated macrophages despite the restriction factor SAMHD1. We reveal inducible changes in expression of cell cycle‐associated proteins including MCM2 and cyclins A, E, D1/D3 in macrophages, without evidence for DNA synthesis or mitosis. These changes are induced by activation of the Raf/MEK/ERK kinase cascade, culminating in upregulation of CDK1 with subsequent SAMHD1 T592 phosphorylation and deactivation of its antiviral activity. HIV infection is limited to these G1‐like phase macrophages at the single‐cell level. Depletion of SAMHD1 in macrophages decouples the association between infection and expression of cell cycle‐associated proteins, with terminally differentiated macrophages becoming highly susceptible to HIV‐1. We observe both embryo‐derived and monocyte‐derived tissue‐resident macrophages in a G1‐like phase at frequencies approaching 20%, suggesting how macrophages sustain HIV‐1 replication in vivo. Finally, we reveal a SAMHD1‐dependent antiretroviral activity of histone deacetylase inhibitors acting via p53 activation. These data provide a basis for host‐directed therapeutic approaches aimed at limiting HIV‐1 burden in macrophages that may contribute to curative interventions.

Highlights

An unresolved question is how HIV-1 achieves efficient replication in terminally differentiated macrophages despite the restriction factor SAMHD1
An increase in viral permissivity under stimulating conditions was observed for single-round VSV-Gpseudotyped HIV-1 virus (Figs 1A and EV1A and B) and full-length infectious HIV-1 molecular clones (Figs 1B and C, and EV1C and D), including macrophage tropic viruses (BaL, YU-2), clinical HIV-1 isolates (Fig EV1C and D) and HIV-1 with capsid mutations known to alter interactions with cyclophilin and CPSF6 leading to altered reverse transcription, retargeted integration and triggering of innate sensing (Fig EV1E)
We observed an increase in cyclins A and E, E2F6 and Geminin—all known to accumulate during cell cycle entry (Coverley et al, 2002; Bertoli et al, 2013; Fragkos et al, 2015)

Summary

Introduction

An unresolved question is how HIV-1 achieves efficient replication in terminally differentiated macrophages despite the restriction factor SAMHD1. We reveal inducible changes in expression of cell cycle-associated proteins including MCM2 and cyclins A, E, D1/D3 in macrophages, without evidence for DNA synthesis or mitosis These changes are induced by activation of the Raf/MEK/ERK kinase cascade, culminating in upregulation of CDK1 with subsequent SAMHD1 T592 phosphorylation and deactivation of its antiviral activity. Depletion of SAMHD1 in macrophages decouples the association between infection and expression of cell cycle-associated proteins, with terminally differentiated macrophages becoming highly susceptible to HIV-1 We observe both embryo-derived and monocyte-derived tissueresident macrophages in a G1-like phase at frequencies approaching 20%, suggesting how macrophages sustain HIV-1 replication in vivo. We reveal a SAMHD1-dependent antiretroviral activity of histone deacetylase inhibitors acting via p53 activation These data provide a basis for host-directed therapeutic approaches aimed at limiting HIV-1 burden in macrophages that may contribute to curative interventions

Methods

Results

Conclusion