Identification of inhibitors of α2β1 integrin, members of C-lectin type proteins, in Echis sochureki venom

Abstract

Snake venom antagonists of α2β1 integrin have been identified as members of a C-lectin type family of proteins (CLP). In the present study, we characterized three new CLPs isolated from Echis sochureki venom, which interact with this integrin. These proteins were purified using a combination of gel filtration, ion exchange chromatography and reverse phase HPLC. Sochicetin-A and sochicetin-B potently inhibited adhesion of cells expressing α2β1 integrin and binding of isolated α2β1 ectodomain to collagen I, as well as bound to recombinant GST-α2A domain in ELISA, whereas activity of sochicetin-C in these assays was approximately two orders of magnitude lower. Structurally, sochicetin-B and sochicetin-C are typical heterodimeric αβ CLPs, whereas sochicetin-A exhibits a trimer of its subunits (αβ)3 in the quaternary structure. Immobilized sochicetins supported adhesion of glioma cell lines, LN18 and LBC3, whereas in a soluble form they partially inhibited adhesion of these cells to collagen I. Glioma cells spread very poorly on sochicetin-A, showing no cytoskeleton rearrangement typical for adhesion to collagen I or fibronectin. Adhesion on CLP does not involve focal adhesion elements, such as vinculin. Sochicetin-A also inhibited collagen-induced platelet aggregation, similar to other CLPs’ action on the blood coagulation system.

The role of platelets in hemostasis and the effects of snake venom toxins on platelet function

“…It presents the quaternary structure (αβ) 3 . It interacts with α 2 β 1 integrin ( Figure 8) and inhibits platelet aggregation induced by collagen (Jakubowski et al, 2013). Other snaclecs, shown in Figure 8 (bilinexin from A. bilineatus, bitiscetin from Bitis arientans, botrocetin from B. jararaca, mucetin from T. mucrosquamatus, and convulxin from C. durissus terrificus) are also able to induce platelet aggregation (Chung et al, 2001;Clemetson et al, 2005;Du et al, 2001;Hirotsu et al, 2001;Lu et al, 2004;Polgár et al, 1997).…”

“…Finally, the KTS and RTS disintegrins belong to the third group. They are potent and selective inhibitors of α 1 β 1 integrin, a specific type IV collagen receptor (Calvete, 2013;Marcinkiewicz, 2005).…”

“…Some snaclecs act as inhibitors of platelet function, while others can activate platelets (Clemetson, 2010;Clemetson et al, 2005). As shown in Figure 8, the GPIb and GPVI receptors and α2β1 integrin as well as C-type lectin-like receptor 2 (CLEC-2) are major receptors of platelet membranes, which the snaclecs bind to (Clemetson, 2010;Jakubowski et al, 2013;Suzuki-Inoue et al, 2006).…”

Biotoxins for Cancer Therapy

“…Disintegrins are a family of small proteins (45-84 amino acids in length), many of which are found in snake venom that function as potent inhibitors of both platelet aggregation and integrin-dependent cell adhesion (Jakubowski et al, 2013;Lucena et al, 2014). Salmosin is a disintegrin purified from venom of a Korean snake, interacts with integrin and induces apoptotic cell death by competing with the extracellular matrix for direct binding to integrin on the cell surface (Hong et al, 2003).…”

Applications of snake venom components to modulate integrin activities in cell–matrix interactions

“…Mass spectroscopy analysis indicated that this type of CLP molecule may occur in Bitis nasicornis venom (Calvete et al, 2007b). Our recent studies revealed that sochicetin-A, a newly isolated CLP may also be oligomerized in the (αβ) 3 fashion (Jakubowski et al, 2013). However, crystallography studies are required to confirm the presence of these types of CLP oligomers.…”