E-cadherin and PD-1 interaction via their N-terminal ectodomains establishes a novel inhibitory axis modulating T cell function 2258851

Abstract Introduction E-cadherin, a member of the cadherin superfamily, is well known for mediating cell-cell adhesion. Recent studies suggest an immunomodulatory role, notably via interaction with the inhibitory receptor KLRG1 on NK cells and T cells. Using biophysical assays, in vitro T cell studies, and structure-guided mutagenesis, we identified and mapped a novel interaction between E-cadherin and PD-1, an inhibitory receptor primarily expressed on T cells. Methods The N-terminal ectodomains of E-cadherin and PD-1 were expressed and purified for interaction analysis by surface plasmon resonance. Fluorophore-conjugated E-cadherin tetramers were used in flow cytometry to assess binding to PD-1 on T cells. Functional outcomes of this interaction were evaluated, and bulk transcriptomic profiling was performed to elucidate underlying mechanisms. Structure-guided mutagenesis, combined with biophysical and functional assays, was employed to map the binding interface. Results Surface Plasmon Resonance analysis using purified N-terminal ectodomains of E-cadherin and PD-1 revealed a direct and specific interaction between the two proteins. A high-avidity E-cadherin probe confirmed binding on PD-1+ murine T cells. Functionally, this interaction significantly inhibited CD4+ and CD8+ T cell activity. Transcriptomic profiling revealed altered migration pathways and induction of FOXO signaling, consistent with a regulatory phenotype. Structure-guided mutagenesis, supported by biophysical and functional assays, indicated a distinct yet partially overlapping binding interface compared to the canonical PD-1:PD-L1 interaction. Conclusion Our findings reveal a previously unrecognized immunoregulatory axis in which E-cadherin directly engages PD-1 via N-terminal ectodomains to suppress T cell function. Given E-cadherin’s broad expression in peripheral tissues and some tumors, this novel PD-1:E-cadherin interaction may play a critical role in immune tolerance and tumor immune evasion. Funding Source MoE-STARS (Govt. of India) /STARS-2/2023-0284 dated 26-09-2023 Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)