Aegyptin, a Novel Mosquito Salivary Gland Protein, Specifically Binds to Collagen and Prevents Its Interaction with Platelet Glycoprotein VI, Integrin α2β1, and von Willebrand Factor

Abstract

Blood-sucking arthropods have evolved a number of inhibitors of platelet aggregation and blood coagulation. In this study we have molecularly and functionally characterized aegyptin, a member of the family of 30-kDa salivary allergens from Aedes aegypti, whose function remained elusive thus far. Aegyptin displays a unique sequence characterized by glycine, glutamic acid, and aspartic acid repeats and was shown to specifically block collagen-induced human platelet aggregation and granule secretion. Plasmon resonance experiments demonstrate that aegyptin binds to collagen types I-V (K d ≈ 1 nM) but does not interact with vitronectin, fibronectin, laminin, fibrinogen, and von Willebrand factor (vWf). In addition, aegyptin attenuates platelet adhesion to soluble or fibrillar collagen. Furthermore, aegyptin inhibits vWf interaction with collagen type III under static conditions and completely blocks platelet adhesion to collagen under flow conditions at high shear rates. Notably, aegyptin prevents collagen but not convulxin binding to recombinant glycoprotein VI. These findings suggest that aegyptin recognizes specific binding sites for glycoprotein VI, integrin ␣2␤1, and vWf, thereby preventing collagen interaction with its three major ligands. Aegyptin is a novel tool to study collagen-platelet interaction and a prototype for development of molecules with antithrombotic properties.

Dipetalodipin, a Novel Multifunctional Salivary Lipocalin That Inhibits Platelet Aggregation, Vasoconstriction, and Angiogenesis through Unique Binding Specificity for TXA2, PGF2α, and 15(S)-HETE

“…Microfluor black microtiter 96-well plates (ThermoLabsystems, Franklin, MA) were coated with 2 g of fibrillar (Horm) or soluble collagen overnight at 4°C in PBS, pH 7.2, essentially as described (16) and in the supplemental data.…”

An insight into the sialotranscriptome of the non-blood feeding Toxorhynchites amboinensis mosquito

“…The 30 kDa antigen in Ae. aegypti was recently shown to inhibit collagen-induced platelet aggregation (Calvo et al, 2007b). This Toxorhynchites peptide may have originated from a member of the 30-kDa antigen family to produce a product with a different function.…”

The secreted salivary proteome of the pea aphid Acyrthosiphon pisum characterised by mass spectrometry

“…As well as acting as a lubricant, for example softening dry and tough food, animal saliva can contain bioactive compounds, including enzymes and other proteins, that variously initiate digestion, assist penetration of food and, for animals feeding on living prey, subdue or circumvent prey defences. The bioactive compounds in blood-feeding animals, such as mosquitoes and ticks, include proteins with anticoagulant, anti-inflammatory and immunosuppressive properties [1][2][3][4][5]. The saliva in plant-feeding insects is predicted to contain an analogous suite of bioactive compounds that modulate, suppress or circumvent plant defences, allowing the insect sufficient time to feed [6][7][8][9].…”