ADAM-mediated ectodomain shedding of HB-EGF in receptor cross-talk

All ligands of the epidermal growth factor receptor (EGFR) which has important roles in development and disease, are shed from the plasma membrane by metalloproteases. The ectodomain shedding of EGFR ligands has emerged as a critical component in the functional activation of EGFR in the interreceptor cross-talk. Identification of the sheddases for EGFR ligands using mouse embryonic cells lacking candidate sheddases (a disintegrin and metalloprotease; ADAM) has revealed that ADAM10, -12 and -17 are the sheddases of the EGFR ligands in response to various shedding stimulants such as GPCR agonists, growth factors, cytokines, osmotic stress, wounding and phorbol ester. Among the EGFR ligands, heparin-binding EGF-like growth factor (HB-EGF) is a representative ligand to understand the pathophysiological roles of the ectodomain shedding in wound healing, cardiac diseases, etc. Here we focus on the ectodomain shedding of HB-EGF by ADAMs, which is not only a key event of receptor cross-talk but also a novel intercellular signaling by the carboxy-terminal fragment (CTF signal).