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Identification of the coagulation factor VIIa integrin binding site required for pro-angiogenic PAR2 signaling

Andrea S. Rothmeier, Enbo Liu, Sagarika Chakrabarty, Jennifer Disse, Barbara M. Mueller, Henrik Østergaard and Wolfram Ruf

Key points

  • The FVIIa integrin binding motif is required for TF-FVIIa complex formation with integrin β1 and pro-angiogenic signaling.

  • The arf6 integrin recycling pathway controls TF-FVIIa signaling and cell surface availability for procoagulant activity.

Abstract

The tissue factor (TF) pathway serves both hemostasis and cell signaling, but how cells control these divergent functions of TF remains incompletely understood. TF is the receptor and scaffold of coagulation proteases cleaving protease activated receptor (PAR) 2 that plays pivotal roles in angiogenesis and tumor development. Here we demonstrate that coagulation factor (F) VIIa elicits TF cytoplasmic domain-dependent pro-angiogenic cell signaling independent of the alternative PAR2 activator matriptase. We identify a Lys-Gly-Glu (KGE) integrin binding motif in the FVIIa protease domain that is required for association of the TF-FVIIa complex with the active conformer of integrin β1. A point mutation in this motif markedly reduces TF-FVIIa association with integrins, attenuates integrin translocation into early endosomes and reduces delayed mitogen activated protein kinase phosphorylation required for the induction of pro-angiogenic cytokines. Pharmacological or genetic blockade of the small GTPase arf6 regulating integrin trafficking increases availability of TF-FVIIa with procoagulant activity on the cell surface, while inhibiting TF-FVIIa signaling leading to pro-angiogenic cytokine expression and tumor cell migration. These experiments delineate the structural basis for the crosstalk of the TF-FVIIa complex with integrin trafficking and suggest a crucial role for endosomal PAR2 signaling in pathways of tissue repair and tumor biology.

  • Submitted February 10, 2017.
  • Accepted December 12, 2017.