摘要
EphB receptors provide crucial adhesive and repulsive signals during cell migration and axon guidance, but it is unclear how they switch between these opposing responses. Here we provide evidence of an important role for matrix metalloproteinases (MMPs) in repulsive EphB2 signaling. We found that EphB2 is cleaved by MMPs both in vitro and in vivo, and that this cleavage is induced by interaction with its ligand ephrin-B2. Our findings demonstrate that MMP-2/MMP-9-specific inhibition or cleavage-resistant mutations in the ectodomain of EphB2 can prevent EphB2-mediated cell-cell repulsion in HEK293 cells, and block ephrin-B1-induced growth cone withdrawal in cultured hippocampal neurons. Transient expression of wtEphB2, but not noncleavable EphB2-4/5 mutant, restored ephrin-B1-induced growth cone collapse and withdrawal in EphB-deficient neurons. The inhibition of EphB2 cleavage also had potent regulatory effects on EphB2 activity. This study provides the first evidence that MMP-mediated cleavage of EphB2 is induced by receptor-ligand interactions at the cell surface and that this event triggers cell-repulsive responses. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.