HIV-1 Vpr up-regulates expression of ligands for the activating NKG2D receptor and promotes NK cell–mediated killing

Abstract

HIV up-regulates cell-surface expression of specific ligands for the activating NKG2D receptor, including ULBP-1, -2, and -3, but not MICA or MICB, in infected cells both in vitro and in vivo. However, the viral factor(s) involved in NKG2D ligand expression still remains undefined. HIV-1 Vpr activates the DNA damage/stress-sensing ATR kinase and promotes G(2) cell-cycle arrest, conditions known to up-regulate NKG2D ligands. We report here that HIV-1 selectively induces cell-surface expression of ULBP-2 in primary CD4(+) T lymphocytes by a process that is Vpr dependent. Importantly, Vpr enhanced the susceptibility of HIV-1-infected cells to NK cell-mediated killing. Strikingly, Vpr alone was sufficient to up-regulate expression of all NKG2D ligands and thus promoted efficient NKG2D-dependent NK cell-mediated killing. Delivery of virion-associated Vpr via defective HIV-1 particles induced analogous biologic effects in noninfected target cells, suggesting that Vpr may act similarly beyond infected cells. All these activities relied on Vpr ability to activate the ATR-mediated DNA damage/stress checkpoint. Overall, these results indicate that Vpr is a key determinant responsible for HIV-1-induced up-regulation of NKG2D ligands and further suggest an immunomodulatory role for Vpr that may not only contribute to HIV-1-induced CD4(+) T-lymphocyte depletion but may also take part in HIV-1-induced NK-cell dysfunction.

Distinct Roles for Human Cytomegalovirus Immediate Early Proteins IE1 and IE2 in the Transcriptional Regulation of MICA and PVR/CD155 Expression

“…To gain insights into the molecular mechanisms regulating the expression of activating ligands in infected cells, we investigated the role of DDR, a host cell pathway that positively affects the expression of activating ligands (35)(36)(37)(38)(39)(40)(41)(42)(43) and that it is activated by HCMV (26,27,(29)(30)(31)(32)(33)(34). Nevertheless, in HCMV-infected HFFs, MICA, ULBP3, and PVR were still increased even when ATM, ATR, and/or DNA-PK were knocked down, thus indicating that these DDR kinases are not involved in the HCMV-mediated ligand stimulation, similar to what has been reported for murine NKG2DL during murine CMV infection (78).…”

“…As previous studies reported that HCMV manipulates the DDR (26,27,(29)(30)(31)(32)(33)(34), a pathway able to stimulate NKG2DL and DNAM-1L expression as well (35)(36)(37)(38)(39)(40)(41)(42)(43), we examined the involvement of DDR signaling in the HCMV-mediated upregulation of activating ligands using genetic and pharmacological approaches.…”

“…DDR is activated by many viruses, including HCMV, and although its functional relevance in HCMV infection has not been clarified, this virus induces DDR, including activation of ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3-related protein (ATR), and the downstream protein H2AX (26,27,(29)(30)(31)(32)(33)(34). Interestingly, expression of some NKG2DL and DNAM-1L can be dependent on the activation of DDR and on ATM/ATR kinases (35)(36)(37)(38)(39)(40)(41)(42)(43).…”

CD4 mimetics sensitize HIV-1-infected cells to ADCC

“…293T human embryonic kidney (obtained from ATCC), CEM.NKr cells (obtained from David Evans, Harvard Medical School), and primary cells were grown as previously described (12,51). CD4 T lymphocytes were purified from rested PBMCs by negative selection and activated as previously described (11).…”

“…pNL43-ADA(Env)-GFP.IRES.Nef proviral vectors (deleted for vpu, nef, and nef and vpu or expressing the D368R Env variant) and the VSVG-encoding plasmid (pSVCMV-IN-VSV-G) were previously described (12,51). T/F and corresponding 6-mo consensus IMCs of patients CH58 and CH77 were inferred, constructed, and biologically characterized as described (36)(37)(38)(39).…”