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Animal venoms are natural products that have served as a source of novel molecules that have inspired novel drugs for several diseases, including for metabolic diseases such as type-2 diabetes and obesity. From venoms, toxins such as exendin-4 (Heloderma suspectum) and crotamine (Crotalus durissus terrificus) have demonstrated their potential as treatments for obesity. Moreover, other toxins such as Phospholipases A2 and Disintegrins have shown their potential to modulate insulin secretion in vitro. This suggests an unexplored diversity of venom peptides with a potential anti-obesogenic in Mexican rattlesnake venoms. For that reason, this study explored the in vitro effect of Crotalus venom peptide-rich fractions on models for insulin resistance, adipocyte lipid accumulation, antioxidant activity, and inflammation process through nitric oxide production inhibition. Our results demonstrated that the peptide-rich fractions of C. aquilus, C. ravus, and C. scutulatus scutulatus were capable of reverting insulin resistance, enhancing glucose consumption to normal control; C. culminatus, C. molossus oaxacus, and C. polystictus diminished the lipid accumulation on adipocytes by 20%; C. aquilus, C. ravus, and C. s. salvini had the most significant cellular antioxidant activity, having nearly 80% of ROS inhibition. C. aquilus, C. pyrrhus, and C. s. salvini inhibited nitric oxide production by about 85%. We demonstrated the potential of these peptides from Crotalus venoms to develop novel drugs to treat type-2 diabetes and obesity. Moreover, we described for the first time that Crotalus venom peptide fractions have antioxidant and inflammatory properties in vitro models.

En este trabajo presentamos una revisión sobre hallazgos más relevantes de la neurofibromatosis tipo 2 (NF2), la cual se conoce por ser un desorden autosómico dominante caracterizado por la presencia de schwannomas vestibulares bilaterales, aunque pueden presentarse otros tumores como meningiomas y ependimomas. Esta enfermedad es causada por diversas mutaciones en el gen NF2, mismo que codifica una proteína conocida como merlina o schwannomina. Merlina está relacionada estructuralmente con la familia de proteínas ERM (Ezrina-Radixina- Moesina), encargadas de acoplar las señales provenientes de las glucoproteínas de la membrana plasmática con el citoesqueleto de actina. El gen NF2 es considerado como un supresor de tumores, y las evidencias indican que merlina funciona regulando la proliferación y el crecimiento celular. Sin embargo, los mecanismos específicos por medio de los cuales merlina cumple con su función siguen siendo un enigma. Se han identificado diversas moléculas que interactúan con merlina, lo que ha proporcionado indicios acerca de los diversos procesos celulares en los cuales esta molécula participa. Entre las proteínas que interactúan con merlina se incluyen proteínas de función estructural, receptores de membrana plasmática, proteínas citosólicas, GTPasas y adaptadores citoesqueléticos. Las mutaciones en el gen NF2 afectan la funcionalidad de merlina, lo que produce alteraciones en los mecanismos de acción de merlina dando como origen a la NF2. Son necesarios más estudios para determinar con certeza el papel de merlina en el control de la proliferación celular. Abstract In this work, we present a review over the most relevant information of the neurofibromatosis type 2 (NF2), which is known as an autosomal dominant disorder characterized by the presence of bilateral vestibular schwannomas. Other tumors such as meningiomas and ependymomas may be present. The disease is caused by mutations in the NF2 gene, which encodes a protein known as merlin or schwannomin. Merlin is structurally related to the ERM (Ezrina-Radixina-Moesina) family of proteins, a group of molecules responsible for linking the signals coming from the plasma membrane glycoproteins to the actin cytoskeleton. The NF2 gene is considered as a tumor suppressor gene, and the evidence indicates that merlin functions by regulating the cell growth and proliferation. However, the specific mechanisms through which merlin fulfill its functions as a tumor suppressor remains enigmatic. Several molecules that interact with merlin have been identified. This has provided clues to determine the cellular processes in which merlin participates. These molecules include structural proteins, plasma membrane receptors, cytosolic proteins, GTPases, and cytoskeletal adapters. Mutations in the NF2 gene affect the functionality of merlin, altering tha mecanisms of action of merlin, giving rise to NF2. Further studies are needed to determine the precise role of merlin on the control of cell proliferation. Keywords: neurofibromatosis type 2, merlin, cytoskeleton, plasma membrane.

Abstract Background Globally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes. Methods Human erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0–640 μg/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination. Results Low concentrations of venom (40 μg/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 μg/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm−1) and lipid peroxidation (2960, 2920 and 1740 cm−1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom. Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.

Chronic wounds are a major health problem that cause millions of dollars in expenses every year. Among all the treatments used, active wound treatments such as enzymatic treatments represent a cheaper and specific option with a fast growth category in the market. In particular, bacterial and plant proteases have been employed due to their homology to human proteases, which drive the normal wound healing process. However, the use of these proteases has demonstrated results with low reproducibility. Therefore, alternative sources of proteases such as snake venom have been proposed. Here, we performed a functional mining of proteases from rattlesnakes (Crotalus ornatus, C. molossus nigrescens, C. scutulatus, and C. atrox) due to their high protease predominance and similarity to native proteases. To characterize Crotalus spp. Proteases, we performed different protease assays to measure and confirm the presence of metalloproteases and serine proteases, such as the universal protease assay and zymography, using several substrates such as gelatin, casein, hemoglobin, L-TAME, fibrinogen, and fibrin. We found that all our venom extracts degraded casein, gelatin, L-TAME, fibrinogen, and fibrin, but not hemoglobin. Crotalus ornatus and C. m. nigrescens extracts were the most proteolytic venoms among the samples. Particularly, C. ornatus predominantly possessed low molecular weight proteases (P-I metalloproteases). Our results demonstrated the presence of metalloproteases capable of degrading gelatin (a collagen derivative) and fibrin clots, whereas serine proteases were capable of degrading fibrinogen-generating fibrin clots, mimicking thrombin activity. Moreover, we demonstrated that Crotalus spp. are a valuable source of proteases that can aid chronic wound-healing treatments.

Loxocelism is a neglected medical problem that depends on its severity, can cause a cutaneous or viscero-cutaneous syndrome. This syndrome is characterized by hemostatic effects and necrosis, and the severity of the loxoscelism depends on the amount of venom injected, the zone of inoculation, and the species. In the Chihuahuan desert, the most abundant species is L. apachea. Its venom and biological effects are understudied, including neurological effects. Thus, our aim is to explore the effect of this regional species of medical interest in the United States-Mexico border community, using rat blood and central nervous system (CNS), particularly, two brain structures involved in brain homeostasis, Area postrema (AP) and Choroid plexus (PC). L. apachea specimens were collected and venom was obtained. Different venom concentrations (0, 0.178 and 0.87 μg/g) were inoculated into Sprague-Dawley rats (intraperitoneal injection). Subsequently, blood was extracted and stained with Wright staining; coronal sections of AP were obtained and stained with Hematoxylin-Eosin (HE) staining and laminin γ immunolabelling, the same was done with CP sections. Blood, AP and CP were observed under the microscope and abnormalities in erythrocytes and fluctuation in leukocyte types were described and quantified in blood. Capillaries were also quantified in AP and damage was described in CP. L. apachea venom produced a segmented neutrophil increment (neutrophilia), lymphocyte diminishment (leukopenia) and erythrocytes presented membrane abnormalities (acanthocytosis). Extravasated erythrocytes were observed in HE stained sections from both, AP and CP, which suggest that near to this section a hemorrhage is present; through immunohistofluorescence, a diminishment of laminin γ was observed in AP endothelial cells and in CP ependymal cells when these structures were exposed to L. apachea venom. In conclusion, L. apachea venom produced leukopenia, netrophilia and acanthocytosis in rat peripheral blood, and also generated hemorrhages on AP and CP through degradation of laminin γ.