ADAM17 targeting by human cytomegalovirus remodels the cell surface proteome to simultaneously regulate multiple immune pathways

Abstract

Human cytomegalovirus (HCMV) is a major human pathogen whose life-long persistence is enabled by its remarkable capacity to systematically subvert host immune defenses. In exploring the finding that HCMV infection up-regulates tumor necrosis factor receptor 2 (TNFR2), a ligand for the pro-inflammatory antiviral cytokine TNFα, we found that the underlying mechanism was due to targeting of the protease, A Disintegrin And Metalloproteinase 17 (ADAM17). ADAM17 is the prototype ‘sheddase’, a family of proteases that cleaves other membrane-bound proteins to release biologically active ectodomains into the supernatant. HCMV impaired ADAM17 surface expression through the action of two virally-encoded proteins in its U L / b’ region, UL148 and UL148D. Proteomic plasma membrane profiling of cells infected with an HCMV double-deletion mutant for UL148 and UL148D with restored ADAM17 expression, combined with ADAM17 functional blockade, showed that HCMV stabilized the surface expression of 114 proteins ( P < 0.05) in an ADAM17-dependent fashion. These included reported substrates of ADAM17 with established immunological functions such as TNFR2 and jagged1, but also numerous unreported host and viral targets, such as nectin1, UL8, and UL144. Regulation of TNFα-induced cytokine responses and NK inhibition during HCMV infection were dependent on this impairment of ADAM17. We therefore identify a viral immunoregulatory mechanism in which targeting a single sheddase enables broad regulation of multiple critical surface receptors, revealing a paradigm for viral-encoded immunomodulation.

Highly Multiplexed Proteomic Analysis of HCMV-Infected Dendritic Cells Reveals Global Manipulation of Adaptive Immunity and Host Restriction of Viral Replication

“…HCMV has the largest genome of any human virus, encoding over 170 ORFs, of which only 41-45 are essential for replication 55,56 , with the remainder encoding accessory functions. Although the function of many of these are unknown, over 19 genes and one microRNA target cell-surface ligands for NK cells 3,29,57 , and at least four genes target cell-surface MHC-I to limit CD8 + T-cell activation 7 . Our data now reveal that in addition to genes targeting MHC-II 58 , the virus is also likely to encode a wide range of additional modulators that target proteins that are absent from HFFFs but present in APCs, and that are capable of altering APC function.…”

HCMV-secreted glycoprotein gpUL4 inhibits TRAIL-mediated apoptosis and NK cell activation

“…In HCMV, the RL11 gene family is associated with a series of immunological functions: RL11 and RL13 each encode IgG-binding proteins ( 66 , 67 ), UL7 encodes an FLT3 ligand ( 68 ), UL8 an inhibitor of cytokine secretion ( 69 , 70 ), UL10 an inhibitor of T cell activation, and UL11 targets CD45 ( 71 – 73 ). Following expression as surface glycoproteins, the ectodomains of UL7, UL8, and UL10 can be released into the supernatant following proteolytic cleavage, although in the case of UL7 and UL8 this is prevented during infection because HCMV inhibits the activity of the metalloprotease responsible (ADAM17) ( 74 ). Interestingly, Adenovirus type 19a also contains a single RL11 homologue which is capable of suppressing NK and T cell function via a direct interaction with CD45 and can also be released from cells by proteolytic cleavage ( 75 ).…”

Downregulation of endogenous nectin1 in human keratinocytes by herpes simplex virus 1 glycoprotein D excludes superinfection but does not affect NK cell function

“…CD14 − CD3 − CD56 + NK cells were purified directly ex vivo via FACS and stimulated to generate NK cell lines as described previously [ 35 ]. nTERT cells were infected with HSV1 at an m.o.i.…”