HIV-2/SIV Vpx antagonises NF-κB activation by targeting p65

Abstract

Background The NF-κB family of transcription factors and associated signalling pathways are abundant and ubiquitous in human immune responses. Activation of NF-κB transcription factors by viral pathogen-associated molecular patterns, such as viral RNA and DNA, is fundamental to anti-viral innate immune defences and pro-inflammatory cytokine production that steers adaptive immune responses. Diverse non-viral stimuli, such as lipopolysaccharide and cytokines, also activate NF-κB and the same anti-pathogen gene networks. Viruses adapted to human cells often encode multiple proteins targeting the NF-κB pathway to mitigate the anti-viral effects of NF-κB-dependent host immunity. Results In this study we have demonstrated using a variety of assays, in a number of different cell types including primary cells, that plasmid-encoded or virus-delivered simian immunodeficiency virus (SIV) accessory protein Vpx is a broad antagonist of NF-κB signalling active against diverse innate NF-κB agonists. Using targeted Vpx mutagenesis, we showed that this novel Vpx phenotype is independent of known Vpx cofactor DCAF1 and other cellular binding partners, including SAMHD1, STING and the HUSH complex. We found that Vpx co-immunoprecipitated with canonical NF-κB transcription factor p65, but not NF-κB family members p50 or p100, preventing nuclear translocation of p65. We found that broad antagonism of NF-κB activation by Vpx was conserved across distantly related lentiviruses as well as for Vpr from SIV Mona monkey (SIVmon), which has Vpx-like SAMHD1-degradation activity. Conclusions We have discovered a novel mechanism by which lentiviruses antagonise NF-κB activation by targeting p65. These findings extend our knowledge of how lentiviruses manipulate universal regulators of immunity to avoid the anti-viral sequelae of pro-inflammatory gene expression stimulated by both viral and extra-viral agonists. Importantly our findings are also relevant to the gene therapy field where virus-like particle associated Vpx is routinely used to enhance vector transduction through antagonism of SAMHD1, and perhaps also through manipulation of NF-κB. Graphical Abstract

Genetic Modification of Primary Human Myeloid Cells to Study Cell Migration, Activation, and Organelle Dynamics

“…2C). However, we cannot rule out that Vpx influences other aspects of myeloid cell biology unseen here, which may include alterations in interferon signaling, NF-κB activity, and gene silencing (Chougui et al, 2018;Cingoz, Arnow, Puig Torrents, & Bannert, 2021;Fink et al, 2022;Yurkovetskiy et al, 2018). Nevertheless, genetic modification of MDDCs through lentiviral-mediated gene delivery can be a useful tool for testing hypotheses related to cell activation, virus infection, and cell-cell communication.…”

Reviewing the Potential Links between Viral Infections and TDP-43 Proteinopathies

“…Furthermore, NF-κB resulted to be activated in ALS patients and mouse models [ 126 , 127 ] in a mouse model of progranulin ( GRN )-deficient FTD [ 128 ], in PD patients [ 129 ], in HD patients and mouse models [ 130 ]. Moreover, a role of NF-κB signaling was detected in SARS-CoV-2 [ 131 ], HBV [ 132 ], HIV-1/2 [ 133 , 134 ], CVB3 [ 135 ], and HSV-1 [ 136 ] infection.…”

Mechanistic Interplay between HIV-1 Reverse Transcriptase Enzyme Kinetics and Host SAMHD1 Protein: Viral Myeloid-Cell Tropism and Genomic Mutagenesis

“…The question of how Vpx-coding lentiviruses overcome this effect is under investigation. Some studies have observed that Vpx itself is able to suppress the innate immune antiviral response in monocyte-derived macrophages and monocytic cell lines [ 188 , 189 ]. One proposed mechanism is that Vpx is able to bind to the p65 subunit of NF-κB in order to suppress NF-κB activation [ 189 ].…”

“…Some studies have observed that Vpx itself is able to suppress the innate immune antiviral response in monocyte-derived macrophages and monocytic cell lines [ 188 , 189 ]. One proposed mechanism is that Vpx is able to bind to the p65 subunit of NF-κB in order to suppress NF-κB activation [ 189 ]. This antagonism was conserved amongst Vpx proteins from distantly related lentiviruses and Vpr from SIV mon , which has SAMHD1-degradation activity [ 189 ].…”

“…One proposed mechanism is that Vpx is able to bind to the p65 subunit of NF-κB in order to suppress NF-κB activation [ 189 ]. This antagonism was conserved amongst Vpx proteins from distantly related lentiviruses and Vpr from SIV mon , which has SAMHD1-degradation activity [ 189 ]. This study is especially enticing, considering one suggested mechanism for SAMHD1-mediated immune suppression is at the NF-κB activation level [ 183 , 190 ].…”