Effect of crotapotin on the biological activity of Asp49 and Lys49 phospholipases A(2) from Bothrops snake venoms

Fraction of C. d. collilineatus venom containing crotapotin protects PC12 cells against MPP + toxicity by activating the NGF-signaling pathway

Background

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. There is no effective treatment for neurodegenerative diseases. Snake venoms are a cocktail of proteins and peptides with great therapeutic potential and might be useful in the treatment of neurodegenerative diseases. Crotapotin is the acid chain of crotoxin, the major component of Crotalus durissus collilineatus venom. PD is characterized by low levels of neurotrophins, and synaptic and axonal degeneration; therefore, neurotrophic compounds might delay the progression of PD. The neurotrophic potential of crotapotin has not been studied yet.

Methods

We evaluated the neurotrophic potential of crotapotin in untreated PC12 cells, by assessing the induction of neurite outgrowth. The activation of the NGF signaling pathway was investigated through pharmacological inhibition of its main modulators. Additionally, its neuroprotective and neurorestorative effects were evaluated by assessing neurite outgrowth and cell viability in PC12 cells treated with the dopaminergic neurotoxin MPP+ (1-methyl-4-phenylpyridinium), known to induce Parkinsonism in humans and animal models.

Results

Crotapotin induced neuritogenesis in PC12 cells through the NGF-signaling pathway, more specifically, by activating the NGF-selective receptor trkA, and the PI3K/Akt and the MAPK/ERK cascades, which are involved in neuronal survival and differentiation. In addition, crotapotin had no cytotoxic effect and protected PC12 cells against the inhibitory effects of MPP+ on cell viability and differentiation.

Conclusion

These findings show, for the first time, that crotapotin has neurotrophic/neuroprotective/neurorestorative potential and might be beneficial in Parkinson's disease. Additional studies are necessary to evaluate the toxicity of crotapotin in other cell models.

Immunotherapeutic potential of Crotoxin: anti-inflammatory and immunosuppressive properties

For the past 80 years, Crotoxin has become one of the most investigated isolated toxins from snake venoms, partially due to its major role as the main toxic component in the venom of the South American rattlesnake Crotalus durissus terrificus. However, in the past decades, progressive studies have led researchers to shift their focus on Crotoxin, opening novel perspectives and applications as a therapeutic approach. Although this toxin acts on a wide variety of biological events, the modulation of immune responses is considered as one of its most relevant behaviors. Therefore, the present review describes the scientific investigations on the capacity of Crotoxin to modulate anti-inflammatory and immunosuppressive responses, and its application as a medicinal immunopharmacological approach. In addition, this review will also discuss its mechanisms, involving cellular and molecular pathways, capable of improving pathological alterations related to immune-associated disorders.

Structural analysis of a group III Glu62-phospholipase A2 from the scorpion, Mesobuthus tamulus: Targeting and reversible inhibition by native peptides

Group III phospholipase A(2) enzyme transcript from the Mesobuthus tamulus (Indian red scorpion) codes for three distinct products that include a large enzymatic subunit, a pentameric peptide and a small non-enzymatic subunit. The structures of these two subunits were modeled based on their sequence identity to bee venom PLA(2) and the partial sequence of MU2 adaptin subunit of AP2 clathrin adaptor, respectively. The enzymatic subunit comprises of three helices, the calcium binding loop and a substrate binding hydrophobic channel where the structure is stabilized by four disulfide bonds. The active site of the enzyme shows a catalytic histidine residue. Interestingly, there is a conservative mutation of the conserved aspartic acid, a classical participant of catalysis in this enzyme family, to glutamic acid. However, the side chain oxygen atoms of this glutamate are oriented away from the catalytic histidine implicating the non-participation of this residue in stabilizing the tautomeric conformation of the histidine. The acidic non-enzymatic subunit comprises of extensive hydrophobic residues with a conformation of an anti-parallel β-sheets making it ideal for tissue specific targeting. The native pentapeptide with the sequence Alanine-Arginine-Serine-Alanine-Arginine was docked to the enzymatic subunit. The peptide ligand occupies the hydrophobic cavity and makes a plethora of interactions with the residues in the channel, including a hydrogen bond with the crucial catalytic histidine and coordinate bond with the calcium ion. This ligand has a binding constant (K(D)) of 1.5μM. This makes the ligand a potential reversible inhibitor, ideal to prevent the enzyme from interacting with non-specific molecules enroute to the target. The enzyme-ligand complex also provides a model to understand the stereochemistry required for the design of more potent drug molecules against such enzyme drug targets.

Crystallization and preliminary X-ray crystallographic analysis of the heterodimeric crotoxin complex and the isolated subunits crotapotin and phospholipase A2

Crotoxin, a potent neurotoxin from the venom of the South American rattlesnake Crotalus durissus terrificus, exists as a heterodimer formed between a phospholipase A(2) and a catalytically inactive acidic phospholipase A(2) analogue (crotapotin). Large single crystals of the crotoxin complex and of the isolated subunits have been obtained. The crotoxin complex crystal belongs to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 38.2, b = 68.7, c = 84.2 A, and diffracted to 1.75 A resolution. The crystal of the phospholipase A(2) domain belongs to the hexagonal space group P6(1)22 (or its enantiomorph P6(5)22), with unit-cell parameters a = b = 38.7, c = 286.7 A, and diffracted to 2.6 A resolution. The crotapotin crystal diffracted to 2.3 A resolution; however, the highly diffuse diffraction pattern did not permit unambiguous assignment of the unit-cell parameters.

Long-lasting anti-inflammatory properties of Crotalus durissus terrificus snake venom in mice

In the present study, we investigated the effects of Crotalus durissus terrificus venom (CdtV) on vascular and cellular events of inflammation induced by carrageenan (cg) in mice. To evaluate edema, CdtV (75 microg kg(-1)) was administered subcutaneously before (1h, 7 or 14 days) or after (1, 4 or 48 h) subplantar injection of cg (15 mg kg(-1)) into the mouse right hind paw; to analyze leukocyte influx, cg (200 microL) was injected i.p. in mice. The inhibitory action of CdtV on edema, either before or after cg injection, was prolonged, lasting even 72 h after administration. Besides, CdtV significantly inhibited migration of polymorphonuclear cells to peritoneal cavity when administered before or after cg. Such inhibitory effects of CdtV on edema and cell migration were also compared with well-known anti-inflammatory drugs. The results demonstrated that CdtV, when injected either 7 or 14 days or 1h before cg, induced a more effective and long-lasting anti-inflammatory effect than that observed with classical anti-inflammatory drugs. The association of CdtV with different drugs did not potentialize their actions on cell migration. These results demonstrate that CdtV exhibits long-lasting anti-inflammatory effects.