RESUMO
Honeybee stings are a severe public health problem. Bee venom contains a series of active components, including enzymes, peptides, and biogenic amines. The local reactions observed after envenoming include a typical inflammatory response and pain. Honeybee venom contains some well-known polycationic peptides, such as Melittin, Apamin, MCD peptide, Cardiopep, and Tertiapin. Secapin in honeybee venom was described 38 years ago, yet almost nothing is known about its action. A novel, variant form of this peptide was isolated from the venom of Africanized honeybees (Apis mellifera). This novel peptide, named Secapin-2, is 25 amino acid residues long. Conformational analyses using circular dichroism and molecular dynamics simulations revealed a secondary structure rich in strands and turns, stabilized by an intramolecular disulfide bridge. Biological assays indicated that Secapin-2 did not induce hemolysis, mast cell degranulation or chemotactic activities. However, Secapin-2 caused potent dose-related hyperalgesic and edematogenic responses in experimental animals. To evaluate the roles of prostanoids and lipid mediators in the hyperalgesia and edema induced by this peptide, Indomethacin and Zileuton were used to inhibit the cyclooxygenase and lipoxygenase pathways, respectively. The results showed that Zileuton partially blocked the hyperalgesia induced by Secapin-2 and decreased the edematogenic response. In contrast, Indomethacin did not interfere with these phenomena. Zafirlukast, a leukotriene receptor antagonist, blocked the Secapin-2 induced hyperalgesia and edematogenic response. These results indicate that Secapin-2 induces inflammation and pain through the lipoxygenase pathway in both phenomena.
Assuntos
Venenos de Abelha/química , Edema/induzido quimicamente , Hiperalgesia/induzido quimicamente , Animais , Venenos de Abelha/isolamento & purificação , Venenos de Abelha/farmacologia , Abelhas , Relação Dose-Resposta a Droga , Edema/metabolismo , Hiperalgesia/metabolismo , Masculino , CamundongosRESUMO
Peptides isolated from animal venoms have shown the ability to regulate pancreatic beta cell function. Characterization of wasp venoms is important, since some components of these venoms present large molecular variability, and potential interactions with different signal transduction pathways. For example, the well studied mastoparan peptides interact with a diversity of cell types and cellular components and stimulate insulin secretion via the inhibition of ATP dependent K(+) (K(ATP)) channels, increasing intracellular Ca(2+) concentration. In this study, the insulin secretion of isolated pancreatic islets from adult Swiss mice was evaluated in the presence of synthetic Agelaia MP-I (AMP-I) peptide, and some mechanisms of action of this peptide on endocrine pancreatic function were characterized. AMP-I was manually synthesized using the Fmoc strategy, purified by RP-HPLC and analyzed using ESI-IT-TOF mass spectrometry. Isolated islets were incubated at increasing glucose concentrations (2.8, 11.1 and 22.2 mM) without (Control group: CTL) or with 10 µM AMP-I (AMP-I group). AMP-I increased insulin release at all tested glucose concentrations, when compared with CTL (P < 0.05). Since molecular analysis showed a potential role of the peptide interaction with ionic channels, insulin secretion was also analyzed in the presence of 250 µM diazoxide, a K(ATP) channel opener and 10 µM nifedipine, a Ca(2+) channel blocker. These drugs abolished insulin secretion in the CTL group in the presence of 2.8 and 11.1 mM glucose, whereas AMP-I also enhanced insulin secretory capacity, under these glucose conditions, when incubated with diazoxide and nifedipine. In conclusion, AMP-I increased beta cell secretion without interfering in K(ATP) and L-type Ca(2+) channel function, suggesting a different mechanism for this peptide, possibly by G protein interaction, due to the structural similarity of this peptide with Mastoparan-X, as obtained by modeling.
Assuntos
Hipoglicemiantes/farmacologia , Proteínas de Insetos/farmacologia , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Peptídeos/farmacologia , Venenos de Vespas/química , Animais , Cálcio/metabolismo , Células Cultivadas , Cromatografia Líquida de Alta Pressão , Hipoglicemiantes/síntese química , Proteínas de Insetos/síntese química , Proteínas de Insetos/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Canais KATP/efeitos dos fármacos , Masculino , Camundongos , Peptídeos/síntese química , Espectrometria de Massas por Ionização por Electrospray , Estereoisomerismo , Venenos de Vespas/síntese química , Venenos de Vespas/farmacologia , VespasRESUMO
BACKGROUND: Hereditary angioedema is an autosomal dominant disease characterized by episodes of subcutaneous and submucosal edema. It is caused by deficiency of the C1 inhibitor protein, leading to elevated levels of bradykinin. More than 200 mutations in C1 inhibitor gene have been reported. The aim of this study was to analyze clinical features of a large family with an index case of hereditary angioedema and to determine the disease-causing mutation in this family. METHODS: Family pedigree was constructed with 275 individuals distributed in five generations. One hundred and sixty-five subjects were interviewed and investigated for mutation at the C1 inhibitor gene. Subjects reporting a history of recurrent episodes of angioedema and/or abdominal pain attacks underwent evaluation for hereditary angioedema. RESULTS: We have identified a novel mutation at the C1 inhibitor gene, c.351delC, which is a single-nucleotide deletion of a cytosine on exon 3, resulting in frameshift with premature stop codon. Sequencing analysis of the hypothetical truncated C1 inhibitor protein allowed us to conclude that, if transcription occurs, this protein has no biological activity. Twenty-eight members of the family fulfilled diagnostic criteria for hereditary angioedema and all of them presented the c.351delC mutation. Variation in clinical presentation and severity of disease was observed among these patients. One hundred and thirty-seven subjects without hereditary angioedema did not have the c.351delC mutation. CONCLUSION: The present study provides definitive evidence to link a novel genetic mutation to the development of hereditary angioedema in patients from a Brazilian family.
Assuntos
Angioedemas Hereditários/genética , Proteínas Inativadoras do Complemento 1/genética , Saúde da Família , Mutação da Fase de Leitura , Adolescente , Adulto , Idade de Início , Idoso , Sequência de Aminoácidos , Sequência de Bases , Brasil , Criança , Pré-Escolar , Proteínas Inativadoras do Complemento 1/metabolismo , Proteína Inibidora do Complemento C1 , Complemento C4/metabolismo , Éxons , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Linhagem , Deleção de Sequência , Adulto JovemRESUMO
Tuberculosis is considered a worldwide health problem mainly due to co-infection with HIV and proliferation of multi-drug-resistant strains. The enzymes of the shikimate pathway are potential targets for the development of new therapies because they are essential for bacteria, but absent from mammals. The last step in this pathway is performed by chorismate synthase (CS), which catalyzes the conversion of 5-enolpyruvylshikimate-3-phosphate (EPSP) to chorismate. The aim of this article is to review the available information on chorismate synthase from Mycobacterium tuberculosis.