Adenosine A2A Receptor Stimulation Inhibits TCR-Induced Notch1 Activation in CD8+T-Cells

Abstract

Notch receptors signaling is required for optimal T-cell activation and function. T-cell receptor (TCR) engagement can activate Notch receptors in T-cells in a ligand-independent fashion. In this study, we examined the role of adenosine A2A receptor (A2AR) signaling pathway in regulating the activity of Notch1 induced by TCR stimulation in CD8+T-cells. A selective A2AR agonist decreased Notch1 protein expression and Notch1 cleavage, and reduced transcripts of Notch1-target genes Hes1 and Myc in activated CD8+T-cells. Inhibition of TCR-induced Notch1 expression by an A2AR agonist was accompanied by increased cAMP concentration and mimicked by forskolin. This effect was associated with reduced IFN-γ and granzyme B production. The effect of an A2AR agonist was abrogated by a selective A2AR antagonist and absent in CD8+T-cells harvested from A2AR−/− mice. Stimulation of A2AR reduced Notch1 receptor levels by inhibiting upstream TCR signals, including ZAP70 phosphorylation, in turn impairing the generation of the active Notch1 intracellular domain (N1ICD). Direct activation of PKC with PMA and ionomycin bypassed A2AR-induced Notch1 inhibition. Overexpression of N1ICD in CD8+T-cells prevented the suppressive effects of an A2AR agonist on proliferation and cytokine release during activation. Our results identify the A2AR signaling pathway as an important regulator of TCR-induced Notch1 receptor activation in CD8+T-cells, and Notch as an important target of the immune suppressive effects of A2AR. We propose a mechanism whereby A2AR impairs CD8 T-cells function through inhibition of Notch1 receptor activation.

The role of the CD39–CD73–adenosine pathway in liver disease

“…The produced adenosine exerts its biological function by binding to one of the four G protein‐coupled adenosine receptors. Among them, A2AR inhibits a series of immune activation‐related signaling pathways, such as LCK proto‐oncogene, Src family tyrosine kinase (LCK), mitogen‐activated protein kinase (MAPK), protein kinase C, and serine/threonine‐protein kinase (AKT) by activating protein kinase A (PKA) and C‐terminal Src kinase, thereby exerting immunosuppressive effects (Linden & Cekic, 2012; Sorrentino et al, 2019).…”

Frequency of circulating CD8+CD73+T cells is associated with survival in nivolumab-treated melanoma patients

“…CD73 is expressed by cancer cells, endothelial cells, exosomes, and immune cell populations: predominantly T cells and, to a lesser extent, B cells, natural killer (NK) and myeloid-derived suppressor cells (MDSCs) [12]. Within the tumor microenvironment, under hypoxic conditions, CD73-derived adenosine accumulates and potently suppresses T cell-mediated anti-tumor immune responses, mainly through stimulation of the cyclic AMP-elevating adenosine receptor A2A, reducing cytokines production, proliferation and cytotoxicity [17][18][19][20][21][22]. CD73 is highly expressed in several types of human cancer and often its expression is associated with poor prognosis in different cancer types [23][24][25][26][27].…”

Preventing ATP Degradation by ASO-Mediated Knockdown of CD39 and CD73 Results in A2aR-Independent Rescue of T Cell Proliferation

“…Whereas extracellular ATP and AMP dose dependently reduced proliferation of CD8 + and CD4 + T cells, adenosine analogs NECA, CGS 21680, and CADO had no impact on T cell proliferation, even at a concentration of 1,000 μM ( Figure 4 A). As an inhibitory effect of CGS 21680 on mouse CD8 + T cell proliferation has been reported when the compound was administered on day 0, 26 we performed the same assay but cultured the cells in the presence of ATP, AMP, NECA, CGS 21680, and CADO from day 0 ( Figure 4 B). Proliferation of both CD8 + and CD4 + T cells was decreased with increasing concentrations of extracellular ATP and AMP, whereby the effect of ATP and AMP was less pronounced compared to administration of the compound on day 3.…”