Haemorrhagic snake venom metalloproteases and human ADAM s cleave LRP 5/6, which disrupts cell–cell adhesions in vitro and induces haemorrhage in vivo

Snake venom metalloproteases ( SVMP s) are members of the a disintegrin and metalloprotease ( ADAM ) family of proteins, as they possess similar domains. SVMP s are known to elicit snake venom‐induced haemorrhage; however, the target proteins and cleavage sites are not known. In this work, we identified a target protein of vascular apoptosis‐inducing protein 1 ( VAP 1), an SVMP , relevant to its ability to induce haemorrhage. VAP 1 disrupted cell–cell adhesions by relocating VE ‐cadherin and γ‐catenin from the cell–cell junction to the cytosol, without inducing proteolysis of VE ‐cadherin. The Wnt receptors low‐density lipoprotein receptor‐related proteins 5 and 6 ( LRP 5/6) are known to promote catenin relocation, and are rendered constitutively active in Wnt signalling by truncation. Thus, we examined whether VAP 1 cleaves LRP 5/6 to induce catenin relocation. Indeed, we found that VAP 1 cleaved the extracellular region of LRP 6 and LRP 5. This cleavage removes four inhibitory β‐propeller structures, resulting in activation of LRP 5/6. Recombinant human ADAM 8 and ADAM 12 also cleaved LRP 6 at the same site. An antibody against a peptide including the LRP 6‐cleavage site inhibited VAP 1‐induced VE ‐cadherin relocation and disruption of cell–cell adhesions in cultured cells, and blocked haemorrhage in mice in vivo . Intriguingly, animals resistant to the effects of haemorrhagic snake venom express variants of LRP 5/6 that lack the VAP 1‐cleavage site, or low‐density lipoprotein receptor domain class A domains involved in formation of the constitutively active form. The results validate LRP 5/6 as physiological targets of ADAM s. Furthermore, they indicate that SVMP ‐induced cleavage of LRP 5/6 causes disruption of cell–cell adhesion and haemorrhage, potentially opening new avenues for the treatment of snake bites.