Molecular cloning of disintegrins from Cerastes vipera and Macrovipera lebetina transmediterranea venom gland cDNA libraries: insight into the evolution of the snake venom integrin-inhibition system

We report the cloning and sequence analysis of Cerastes vipera and Macrovipera lebetina transmediterranea cDNAs coding for short non-RGD (Arg-Gly-Asp) disintegrins and for dimeric disintegrin subunits. The mRNAs belong to the short-coding class, suggesting that these disintegrin mRNAs may be more widely distributed than previously thought. Our data also argue for a common ancestry of the mRNAs of short disintegrins and those coding for precursors of dimeric disintegrin chains. The Macrovipera lebetina transmediterranea dimeric disintegrin reported to inhibit the laminin-binding integrins alpha3beta1, alpha6beta1 and alpha7beta1 was analysed using a proteomic approach and was shown to bear MLD (Met-Leu-Asp) and VGD (Val-Gly-Asp) motifs. The results highlight the fact that disintegrins have evolved a restricted panel of integrin-blocking sequences that segregate with defined branches of the phylogenetic tree of the integrin alpha-chains, providing novel insights into the evolutionary adaptation of the snake venom antagonists to the ligand-binding sites of their target integrin receptors.

Structure-Function Relationship of the Disintegrin Family: Sequence Signature and Integrin Interaction

Disintegrins are small cysteine-rich proteins found in a variety of snake venom. These proteins selectively modulate integrin function, heterodimeric receptors involved in cell-cell and cell-matrix interaction that are widely studied as therapeutic targets. Snake venom disintegrins emerged from the snake venom metalloproteinase and are classified according to the sequence size and number of disulfide bonds. Evolutive structure and function diversification of disintegrin family involves a stepwise decrease in the polypeptide chain, loss of cysteine residues, and selectivity. Since the structure elucidation of echistatin, the description of the structural properties of disintegrins has allowed the investigation of the mechanisms involved in integrin-cell-extracellular matrix interaction. This review provides an analysis of the structures of all family groups enabling the description of an expanded classification of the disintegrin family in seven groups. Each group presents a particular disulfide pattern and sequence signatures, facilitating the identification of new disintegrins. The classification was based on the disintegrin-like domain of the human metalloproteinase (ADAM-10). We also present the sequence and structural signatures important for disintegrin-integrin interaction, unveiling the relationship between the structure and function of these proteins.

Crotalus atrox disintegrin reduces hemorrhagic transformation by attenuating matrix metalloproteinase-9 activity after middle cerebral artery occlusion in hyperglycemic male rats

Hemorrhagic transformation after ischemic stroke is an independent predictor for poor outcome and is characterized by blood vessel rupture leading to brain edema. To date, no therapies for preventing hemorrhagic transformation exist. Disintegrins from the venom of Crotalus atrox have targets within the coagulation cascade, including receptors on platelets. We hypothesized that disintegrins from C. atrox venom can attenuate hemorrhagic transformation by preventing activation of matrix metalloproteinase after middle cerebral artery occlusion (MCAO) in hyperglycemic rats. We subjected 48 male Sprague-Dawley rats weighing 240-260 g to MCAO and hyperglycemia to induce hemorrhagic transformation of the infarction. At reperfusion, we administered either saline (vehicle), whole C. atrox venom (two doses were used), or fractionated C. atrox venom (HPLC Fraction 2). Rats were euthanized 24 hr post-ictus for measurement of infarction and hemoglobin volume. Reversed-phase HPLC was performed to fractionate the whole venom and peaks were combined to form Fraction 2, which contained the disintegrin Crotatroxin. Fraction 2 protected against hemorrhagic transformation after MCAO, and attenuated activation of matrix metalloproteinase-9. Administering matrix metalloproteinase antagonists prevented the protection by Fraction 2. The results of this study indicate that disintegrins found in C. atrox venom may have therapeutic potential for reducing hemorrhagic transformation after ischemic stroke. Moreover, the RP-HPLC fractions retained sufficient protein activity to suggest that gentler and less efficient orthogonal chromatographic methods may be unnecessary to isolate proteins and explore their function.