Finding functional gaps: integrative analysis of VPAC1- and VPAC2-mediated signalling pathways in human lymphocytes.

This study identifies distinct signaling pathways for VPAC1 and VPAC2 in T-cells, but the clinical relevance of these findings is not established.

Summary and findings

This study analyzed the signaling pathways of VPAC1 and VPAC2 in human lymphocytes, specifically Jurkat T-cells. The research focused on receptor interactions, second messenger production, and transcriptional responses. No therapeutic claims were made.

Abstract

<h4>Background</h4>Vasoactive Intestinal Peptide (VIP) is a pleiotropic neuropeptide regulating diverse cellular and physiological processes. Its functions are primarily mediated through two G protein-coupled receptors, VPAC1 and VPAC2. The aim of this study was to perform an integrative analysis of VPAC receptor signalling, encompassing receptor-G protein coupling, second messenger production, kinase activation and transcriptional responses in T cells.<h4>Experimental approach</h4>Receptor interactions with Gα subunits were analysed using BRET assays. Stable Jurkat T-cell lines overexpressing VPAC1 (J-OEV1) or VPAC2 (J-OEV2) were generated. VPAC-dependent intracellular signalling in these cells was assessed by measuring cAMP and Ca²⁺ levels, performing phospho-kinase arrays and Western blot analyses, and evaluating immune mediator expression, cell viability, and proliferation.<h4>Results</h4>VPAC1 showed interaction with both Gαs and Gαq subunits, whereas VPAC2 preferentially interacted with Gαs. In Jurkat cells, both receptors overexpression enhanced cAMP signalling, while increased Ca²⁺ responses were restricted to VPAC1. In both J-OEV1 and J-OEV2 cells, VIP treatment reduced phosphorylation of inflammatory kinase-associated proteins. Overexpression of either receptor induced distinct basal transcriptional profiles of transcription factors and cytokines, which were further modulated by CD3/CD28-activation and VIP. While proliferation was not altered with overexpression, J-OEV2 showed a reduced redox metabolism at 72 h.<h4>Conclusion</h4>This study aimed to identify functional differences between VPAC1 and VPAC2 signalling and reveals reproducible subtype-specific differences at early signalling. In Jurkat cells, both receptors induce a shift in its basal state; however, changes do not persist during TCR-driven activation, resulting in largely convergent effector responses.

Key findings

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Limitations

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Elsewhere in the VIP (Vasoactive Intestinal Polypeptide) corpus