HIV-1 Vpr induces ATM-dependent cellular signal with enhanced homologous recombination

We performed an extensive two-dimensional differential in-gel electrophoresis proteomic analysis of the cellular changes in human T cells upon human immunodeficiency virus type 1 (HIV-1) infection. We detected 2,000 protein spots, 15% of which were differentially expressed at peak infection. A total of 93 proteins that changed in relative abundance were identified. Of these, 27 were found to be significantly downregulated and 66 were upregulated at peak HIV infection. Early in infection, only a small group of proteins was changed. A clear and consistent program of metabolic rerouting could be seen, in which glycolysis was downregulated and mitochondrial oxidation enhanced. Proteins that participate in apoptotic signaling were also significantly influenced. Apart from these changes, the virus also strongly influenced levels of proteins involved in intracellular transport. These and other results are discussed in light of previous microarray and proteomic studies regarding the impact of HIV-1 infection on cellular mRNA and protein content.

Section: Discussionsupporting

confidence: 81%

Proteomic Studies Reveal Coordinated Changes in T-Cell Expression Patterns upon Infection with Human Immunodeficiency Virus Type 1

Ringrose

Jeeninga

Berkhout

et al. 2008

“…Other reports in the literature complement our finding that a single viral protein can modulate HDR (29,41). Importantly, this study has identified a novel function for HCMV IE1-72, namely, that sole expression of it can upregulate HDR.…”

supporting

confidence: 74%

Stimulation of Homology-Directed Repair at I-SceI-Induced DNA Breaks during the Permissive Life Cycle of Human Cytomegalovirus

Kulkarni

Fortunato

2011

Human cytomegalovirus (HCMV) selectively relocalizes many DNA repair proteins, thereby avoiding a potentially detrimental damage response. In the present study, we evaluated interactions between HCMV and the homology-directed repair (HDR) pathway. In permissive human foreskin fibroblasts, a fluorescence-based doublestranded break repair assay was used to determine that HCMV stimulated HDR. Repair of both stably integrated and extrachromosomal reporter substrates was observed to increase. HDR was also stimulated through individual expression of the viral immediate-early protein IE1-72, mimicking full virus infection. These experiments further demonstrate HCMV's role in modulating critical cellular processes during a permissive infection.

“…While DDR activation may represent a cell-intrinsic antiviral response, it has been suggested that both RNA and DNA viruses induce DDR signaling to promote cellular conditions that are favorable for viral replication (83,(90)(91)(92)(93). For instance, the induction of DDR signaling activates ataxia telangiectasia mutated (ATM) kinase, which results in the activation of nuclear factor kappa light chain enhancer of activated B cells (NF-B) (94,95). Additionally, the DDR pathway also directly activates proinflammatory responses through the induction of interferon regulatory factors (IRFs) or through the recruitment of coactivators and chromatin-modifying complexes, such as ten-eleven translocation methylcytosine (TET) dioxygenases, which we hypothesize might also activate viral transcription (96).…”

Section: Discussionmentioning

confidence: 99%

Virion-Associated Vpr Alleviates a Postintegration Block to HIV-1 Infection of Dendritic Cells

Miller

Akiyama

Agosto

et al. 2017

Viral protein R (Vpr) is an HIV-1 accessory protein whose function remains poorly understood. In this report, we sought to determine the requirement of Vpr for facilitating HIV-1 infection of monocyte-derived dendritic cells (MDDCs), one of the first cell types to encounter virus in the peripheral mucosal tissues. In this report, we characterize a significant restriction of Vpr-deficient virus replication and spread in MDDCs alone and in cell-to-cell spread in MDDC-CD4 ϩ T cell cocultures. This restriction of HIV-1 replication in MDDCs was observed in a single round of virus replication and was rescued by the expression of Vpr in trans in the incoming virion. Interestingly, infections of MDDCs with viruses that encode Vpr mutants unable to interact with either the DCAF1/DDB1 E3 ubiquitin ligase complex or a host factor hypothesized to be targeted for degradation by Vpr also displayed a significant replication defect. While the extent of proviral integration in HIV-1-infected MDDCs was unaffected by the absence of Vpr, the transcriptional activity of the viral long terminal repeat (LTR) from Vpr-deficient proviruses was significantly reduced. Together, these results characterize a novel postintegration restriction of HIV-1 replication in MDDCs and show that the interaction of Vpr with the DCAF1/DDB1 E3 ubiquitin ligase complex and the yet-to-be-identified host factor might alleviate this restriction by inducing transcription from the viral LTR. Taken together, these findings identify a robust in vitro cell culture system that is amenable to addressing mechanisms underlying Vpr-mediated enhancement of HIV-1 replication.IMPORTANCE Despite decades of work, the function of the HIV-1 protein Vpr remains poorly understood, primarily due to the lack of an in vitro cell culture system that demonstrates a deficit in replication upon infection with viruses in the absence of Vpr. In this report, we describe a novel cell infection system that utilizes primary human dendritic cells, which display a robust decrease in viral replication upon infection with Vpr-deficient HIV-1. We show that this replication difference occurs in a single round of infection and is due to decreased transcriptional output from the integrated viral genome. Viral transcription could be rescued by virion-associated Vpr. Using mutational analysis, we show that domains of Vpr involved in binding to the DCAF1/DDB1/E3 ubiquitin ligase complex and prevention of cell cycle progression into mitosis are required for LTR-mediated viral expression, suggesting that the evolutionarily conserved G 2 cell cycle arrest function of Vpr is essential for HIV-1 replication.