Abstract 488: Glutathione-CaSR Interaction Contributes To Glutathione Regulation Of Angiogenesis

Introduction: In addition to its classic role in redox chemistry, glutathione (GSH) also acts as an allosteric regulator of the calcium-sensing receptor (CaSR). CaSR has been found in a variety of cell types including endothelial cells (ECs), where its activity has been linked to EC adhesion and migration. Although a relationship between GSH and CaSR has been discovered, no link has been established between GSH-CaSR interaction and regulation of angiogenesis. We hypothesize a novel mechanism for GSH regulation of blood vessel development occurs through an extracellular interaction with CaSR as a part of physiological and pathological angiogenesis. Methods: Matrigel tube formation and wound healing assays were used to measure EC activity. RGECO1.2 was used to measure changes in intracellular calcium. Cell surface expression assay was used to measure surface CaSR expression. Cell counts and flow cytometry were used to monitor cell proliferation and cell cycle progression. Endothelial and mesenchymal markers were measured using real-time PCR. Results: Extracellular GSH increased endothelial tube length and branching in tube formation assay, while a selective CaSR inhibitor abrogated these effects. GSH also influenced EC migration as measured by wound healing assay. GSH or a CaSR agonist (R-568) reduced surface CaSR expression, with no changes in intracellular calcium. Extracellular GSH alters EC proliferation and cell cycle progression, coinciding with alterations in endothelial phenotype along the endothelial-mesenchymal spectrum. Conclusion: In addition to its classic antioxidant role, GSH appears to act extracellularly to influence EC activity. GSH caused significant increases in EC branching as measured by tube formation assay. The use of a selective CaSR inhibitor confirms the contribution of CaSR to this effect. Additionally, GSH influenced EC migration in wound healing assays. These results could be explained by GSH-CaSR-mediated alterations in endothelial differentiation. These results suggest a role for GSH in vascular development and angiogenesis, through a ligand interaction with the CaSR G-protein coupled receptor, representing a novel mechanism of action for physiological and pathological blood vessel development.