IP‐10 fragment is the functional motif that blocks endothelial cell motility and vessel formation

Abstract

Angiogenesis plays a critical role in optimum healing of a cutaneous wound. It requires well‐orchestrated integration of soluble and matrix factors and timely recognition of such signals to regulate this process. Previous work has shown that endothelial cells express CXC receptor 3 (CXCR3) late in wound regeneration and its ligand IP‐10 (CXCL10) which influences the cells ability to migrate and form vessels in vitro and in vivo resulting in inhibition and regression in the vascular network. To identify the functional domain of IP‐10 to develop new therapeutic agents to promote or inhibit blood vessel formation we isolated a 21 amino acid fragment, residues 78‐98, which we believe is the functional domain, of IP‐10 and analyzed its ability to modulate endothelial cell tube formation. Treatment of the endothelial cells with the IP‐10 fragment significantly inhibited VEGF‐induced endothelial motility and tube formation, a response critical for angiogenesis. Furthermore, simulation of CXCR3 by the IP‐10 fragments induced an increase in cAMP production and activation of PKA that leads to the inhibition of VEGF‐mediated m‐calpain activation and thereby limits cell motility. This activity is embodied in the minimal IP‐10 fragment. We posit that peptide design provides a novel system to provide desired functions of promoting and inhibiting signaling pathways and angiogenesis in human microvascular endothelial cells.