Expression of a short antibody heavy chain peptide effectively antagonizes adenosine 2A receptor in vitro and in vivo

Adenosine 2A receptor (A_2AR) is involved in many physiological and pathological functions and serves as an important drug target. Inhibition of A_2AR may alleviate symptoms associated with a variety of neuropsychiatric disorders. However, the currently used A_2AR antagonists have specificity limitations. A Fab fragment (Fab2838) of an A_2AR mouse monoclonal antibody can specifically bind to A_2AR to form a complex and inhibit the activity of its receptor. We constructed the vector AntiA_2AR, a small-molecule peptide that binds to and inhibits A_2AR based on Fab2838. Experiments in HEK293T cells showed that peptide AntiA_2AR of 29 peptides was the most effective among the synthesized peptides in inhibiting the A_2AR downstream signal cAMP/PKA/CREB. In neurons, the AntiA_2AR reversed the calcium flow change induced by the A_2AR agonist CGS21680 (1 μM). Furthermore, AntiA_2AR expression in the mice striatum weakened the p-PKA/p-CREB signal, enhanced locomotor abilities and increased time spent in the center area in the home-cage observation experiment and increased anxiolytic behavior in the elevated-plus maze test. Antagonistic peptide AntiA_2AR can effectively block the A_2AR signaling pathway. This provides a new strategy for the specific inhibition of A_2AR and provides information needed for drug development.