CD8‐β ADP‐ribosylation affects CD8⁺T‐cell function

Abstract

Keywords: Antibodies r Cell surface molecules r T cells r Transgenic/knockout mice Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionThe coreceptor of conventional CD8 + T cells consists of a CD8αβ heterodimer. Both chains contribute to the CD8 conformation and binding to peptide:MHC class I (MHC-I) complexes [1]. Correct interaction of CD8, TCR, and peptide:MHC-I is decisive for effective signal transduction upon antigen recognition, and interruption of CD8/peptide:MHC-I interaction impairs MHC-I-restricted immune responses, including cytokine production and cytotoxic effector function.Correspondence: Dr. Timo Lischke e-mail: t.lischke@uke.de Stressed or damaged tissue cells release nicotinamide adenine dinucleotide NAD + and adenosine-5 -triphosphate (ATP) into the extracellular space [2][3][4]. Extracellular ATP and NAD + can act as danger signals and both can induce apoptosis of cells [5][6][7]. High concentrations of extracellular ATP induce gating of the purinoceptor P2X7, which causes Ca 2+ influx, shedding of CD62L, surface exposure of phosphatidylserine, formation of large membrane pores, uptake of propidium iodide, and eventually cell death [8][9][10][11][12]. Likewise, extracellular NAD + can induce T-cell apoptosis [13] via constitutive activation of P2X7 due to ADP-ribosylation at Arg 125 [14][15][16]. In mice, this process is catalyzed by ADPribosyl transferase 2.2 (ART2.2), a glycosyl-phosphatidylinositolanchored ectoenzyme expressed on T cells, that utilizes extracellular NAD + to transfer ADP-ribose to arginine residues in the Extensive ADP-ribosylation of surface proteins of CD8 + T cells interferes with effector functions such as cytotoxicity and cytokine production [23,24]. Here, we identify CD8-β as target for ART2.2-dependent ADPribosylation upon NAD + treatment of CD8 + T cells, which significantly impaired MHC-I tetramer binding, indicating that ADPribosylation interfered with the interaction of TCR, CD8, and MHC-I. In line with this result, NAD + treatment of mice resulted in impaired CD8 + T-cell cytotoxicity. Results CD8-β is a target for ART2.2-mediated ADP-ribosylationIn the course of experiments aiming to characterize CD8 + T cells from different tissues, we observed inconsistent staining profiles for CD8-β. In the liver, the CD8-α + T cells displayed strong staining with the anti-CD8-β mAb H35-17.2, but reduced staining with the anti-CD8-β mAb YTS156.7.7 and 53-5.8. In contrast in the spleen, CD8-α + T cells showed a similar staining profile with all anti-CD8-β mAb used for analysis ( Fig. 1A; the gating strategy for CD8-α + T cells is depicted in Supporting Information Fig. 1). Since CD8-β-staining in the liver was reduced only for certain anti-CD8-β mAb, it was unlikely that the altered staining profile was due to a change in the surface expression level of CD8-β. Rather, the distinct staining profiles for different anti-CD8-β mAb could be due to modification of the epitope recognized by the mAb on CD8-β. ...

Astrocytes and Microglia Are Resistant to NAD+-Mediated Cell Death Along the ARTC2/P2X7 Axis

“…Loss of antibody-binding to ADP-ribosylated proteins has also been described for other ARTC2 target proteins: ADP-ribosylation of CD25 leads to a loss of binging of the clone 7D4 but not of PC61 (Teege et al, 2015). For CD8β, ADP-ribosylation diminishes binding of clones YTS156.7.7 and 53-5.8 but has no influence on the binding of 53-6.7 and H35-17.2 (Lischke et al, 2013). For LFA-1, ADP-ribosylation decreased the binding of mAbs 2D7 and C71/16 but not of mAb M17/4 (Nemoto et al, 1996)).…”

Nucleotide-Induced Membrane-Proximal Proteolysis Controls the Substrate Specificity of T Cell Ecto–ADP-Ribosyltransferase ARTC2.2

“…These results strengthen the conclusion that downmodulation of ARTC2.2 depends on ADP-ribosylation of P2X7. The results also imply that this downmodulation is not caused by obstruction of Ab binding due to ADP-ribosylation of the Ab-binding epitope (38,39).…”

“…ARTC2.2 is a promiscuous ADP-ribosyltransferase that can ADPribosylate several structurally unrelated cell surface proteins, including P2X7, LFA-1, and CD8 (9,38,39). By virtue of its GPI anchor 2) and proteins in the cell supernatants (lanes 3 and 4) were analyzed by SDS-PAGE autoradiography.…”

AP2rx7passenger mutation affects the vitality and function of immune cells in P2X4ko and other transgenic mice

“…In contrast to human T cells, mouse T cells exhibit an alternative way of P2X7 activation, which is triggered by ecto-ADP-ribosyltransferase C2.2 (ARTC2.2). ARTC2.2 utilizes nicotinamide adenine dinucleotide (NAD + ), which is also released as DAMP during tissue damage, to ADP-ribosylate a variety of cell surface proteins such as CD25 (Teege et al, 2015), CD8β (Lischke et al, 2013), FcγR1, FcγR2b (Rissiek et al, 2017) and P2X7 (Seman et al, 2003). ADP-ribosylation of arginine 125 in the extracellular loop of P2X7 (Adriouch et al, 2008) acts like a covalently bound P2X7 agonist .…”