Inhibitory effect of mastoparan-like peptide from wasp (Vespa magnifica) venom on angiogenesis / 中国药理学通报

Aim To investigate the anti-angiogenic effect of 12a, the mastoparan-like peptide from wasp ( Vespa magnifica ) venom. Methods The tube for-mation and proliferation of human umbilical vein endo-thelial cells ( HUVEC ) and chicken chorioallantoic membrane ( CAM) model were used to observe the an-ti-angiogenic effect of 12a in vitro and in vivo, respec-tively. Results In the CAM model, 0. 1 μg or 1 μg of 12 a could markedly inhibit angiogenesis induced by 0. 2 μg rh-bFGF with heavy loss of color, decreasing density and obscure frame of the vessels. The inhibi-tion rates of angiogenesis were 60 . 2 % for 0 . 1 μg and 90. 3 % for 1 μg, respectively. Accordingly, in HU-VEC culture experiment, the proliferation and angio-genesis of HUVEC treated by 1 mg·L-1 and 10 mg· L-1 of 12 a were decreased by 55. 4 %, 39. 3 % and 51. 6 %, 26. 7 %, respectively. Conclusion 12a has a significant anti-angiogenic effect in a concentra-tion-dependent manner.

Exploración estructural de perfiles de actividad antibacteriana y hemolítica de análogos no naturales del péptido antimicrobiano Mastoparán MP-8 / Structural exploration of antibacterial activity and hemolytic profiles of non-natural analogs of the antimicrobial peptide mastoparan MP-8

En este trabajo se reporta el efecto, la modificación puntual y sistemática a nivel del enlace peptídico realizada al péptido Mastoparán MP-8, obteniéndose 27 pseudopéptidos en total. Los resultados permitieron determinar que los pseudopéptidos ψ-38617(INLKALAALAKd-[CH2NH]-RLL), ψ-38629(INLKAd-[CH2NH]-LAALAKRLL) y ψ-38630 (INLK-[CH2NH]-ALAALAKRLL) presentan mejor actividad que el péptido Mastoparán MP-8 frente a las bacterias Gram negativas y conservaron la actividad antibacteriana frente a las bacterias Gram positivas; además, la modificación realizada produjo tres moléculas que abolieron totalmente la actividad hemolítica propia del péptido nativo. Todas las modificaciones realizadas a esta secuencia provocaron un aumento en la estabilidad de las moléculas frente al ataque enzimático.

In this work the relevance of a systematic replacement of peptide-bonds on the Mastoparan MP-8 antimicrobial peptide to afford 27 new pseudopeptide analogues is reported. Results allowed to determine that pseudopeptides ψ-38617 (INLKALAALAKd-[CH2NH]-RLL), ψ-38629(INLKAd-[CH2NH]-LAALAKRLL) and ψ-38630 (INLK-[CH2NH]-ALAALAKRLL), showed an enhanced anti gam-negative bacterial properties, regarding the native Mastoparan MP-8 peptide, but maintaining a comparable activity against gram-positive bacteria. In addition, specific performed modifications on MP-8 sequence led three new molecules that completely abolished the hemolytic activity of the parent MP-8 peptide. All obtained molecules possess a high stability profile when tested against a severe proteolytic attack.

Selective mastoporan inhibition of muscarinic activation of bovine tracheal smooth muscle

Muscarinic activation of bovine tracheal smooth muscle (BTSM) leading to smooth muscle contraction involves the generation of two cGMP signals (20 and 60 s), being 20s peak associated with soluble (sGC) and the second (60s) to membrane-bound Natriuretic Peptide- receptor-Guanylylcy clases (NPR-GC). In this study, we showed that pre-incubation of isolated BTSM strips with mastoparan and superactive mastoparan (mastoparan 7) decreased significantly the muscarinic dependent contractile smooth muscle responses in dose-dependent and non-competitive manner. Moreover, mastoparan (50 nM) inhibited completely the BTSM-muscarinic contractile responses and affected dramatically the carbachol-dependent cGMP signals being the first cGMP signal inhibited in a 63 ± 5%, whereas the second signal disappeared. Mastoparan inhibition of muscarinic activation is specific since other spasmogens as serotonin and histamine fully contracted these BTSM strips under mastoparan treatment. Cyclic GMP levels were evaluated by exposing BTSM strips to activators of NO-sensitive sGC as Sodium Nitroprussiate (SNP) and Natriuretic Peptides as CNP-53 for membrane-bound NPR-GC. Thus, SNP and CNP increased in a binary way, in more than 20 fold cGMP levels at 30-40 s being both increments inhibited by mastoparan. Furthermore, the Gi/o-protein involvement on mastoparan inhibition of cGMP elevations induced by CNP and SNP is suggested by Pertussis toxin pre-treatment, which reversed mastoparan effects. These results indicate that muscarinic signal transduction cascades leading to airway smooth muscle contractions involved two different guanylyl cyclases being both regulated by mastoparan-sensitive G-proteins. ANP, Natriuretic Peptide type A; ASM, Airway Smooth Muscle; BTSM, Bovine Tracheal Smooth Muscle; CNP-53, Natriuretic Peptide type C-53; GPCR, G-Protein Coupled Receptor; Gq16, Heterotrimeric G protein subtype 16; Gi/o, Heterotrimeric G protein subtype...

La activación muscarínica del músculo liso de las vías aéreasrelacionada a la contracción de dicho músculo liso esta asociada a la generación de dos señales de GMPc (20 y 60 s), siendo la señal de los 20s relacionado a la activación de la guanililciclasa soluble mientras que el pico de los 60s a la guanililciclasa unida membranas y sensible a péptidos natriuréticos (NPR-GC). En este trabajo, nosotros mostramos que la pre-incubación de fragmentos del músculo liso traqueal de bovino (BTSM) con mastoparan y su análogo superactivo (mastoparan 7), en una forma dosis dependiente, son capaces de disminuir de manera significativa la actividad contráctil dependiente de agentes muscarinicos. Adicionalmente, mastoparan (50 nM) inhibió completamente la respuesta contráctil muscarinica del BTSM y afectó dramáticamente los picos de GMPc asociados a la activación muscarinica siendola primera señal inhibida en un 63 ± 5%, mientras que la segunda señal desapareció completamente. Esta inhibición del mastoparan de la activación muscarínica es especifica ya que otros espamogenos como la serotonina y la histamina fueron capaces de inducir respuestas máximas en presencia del mastoparan y su análogos. Este efecto del mastoparan sobre los niveles del GMPc fue evaluado en presencia de otros agentes generadores de este segundo mensajero como son el nitroprusiato de sodio (SNP) que activa la guanililciclasa soluble sensible a NO y los péptidos natriureticos como el CNP-53 (CNP) activador de la NPR-GC asociada a membranas plasmáticas. Tanto, el SNP como el CNP aumentaronen mas de 50 veces los niveles de GMPc a los 30-40 s en forma bifasica, siendo estos incrementos inhibidos de manera significativa por el mastoparan. Ademas, se sugiere la participación de proteínas Gi/o en los efectos inhibitoriosdel mastoparan, porque la Toxina pertussis revertió los efectos inhibitorios. Estos resultados indican que la cascada de activación muscarinica que conduce...

Signal mechanism of insulin secretion regulated by bioactive peptides / 中国病理生理杂志

Mastoparan(MAS) and α-latrotoxin(α-LTX) are two kinds of insulinotropic peptides obtained from insect toxins which can interact with islet β-cells and induce insulin secretion. The signal mechanism of these insulinotropic peptides regulating insulin-releasing attracts notable attention and has been elucidated more and more details. MAS mainly acts on the molecular components of exocytosis at a late stage. Insulin secretion induced by MAS is obviously dependent on GTP, which subsequently activates G-protein located on insulin secretion granules(ISG), or activates the Rho subfamily of small G proteins to evoke exocytosis and sensitize fusion machinery. The MAS stimulated insulin-releasing activity can be augmented by nutrients. However, its effect is not Ca~(2+) dependent. There are two regulatory pathway triggered by α-LTX: one way is pore formation caused through plasma membrane, another way is the transmembrane signal transduction evoked by cytosolic second messengers. Tetrameri complexs assembled at high concentration of α-LTX toxin or in the presence of extracellular Ca~(2+), can insert α-LTX into plasma membrane to form Ca~(2+) permeable channels and trigger Ca~(2+)-dependent secretion. By binding to transmembrane receptors and activating phospholipase C, α-LTX induces the generation of second messenger DAG and IP3. IP3 triggers Ca~(2+) influx and subsequently activates CaMK pathway, however, DAG also activates PKC pathway to increase insulin release.

Effect and mechanism of mastoparan-1 antagonizing lipopolysaccharide in vitro / 中华创伤杂志

Objective To investigate the mechanism of mastoparan-1 (MP-1) antagonizing lipopolysaecharide (LPS) in vitro. Methods The affinity of MP-1 for lipid A was assayed by biosensor, and the neutralization of MP-1 on LPS (2 μg/L) was detected by kinetic turbidimetric limulus test. After exposing fluorescin isothiecyanate (FITC) labeled LPS (FITC-LPS) to MP-1 at different concentrations (5, 10, 20, 40 μmol/L), the binding of FITC-LPS to murine RAW264.7 cells was analyzed by laser scanning confocal microscopy. The influence of MP-1 on TLR4 expression in RAW264.7 cells stimulated by LPS (100 μg/L) was detected by immunoeytochemieal staining. The expressions of TLR4, TNF-α and IL-6 at the gene and protein level were detected by RT-PCR and ELISA after exposing LPS (100 μg/ L) stimulated RAW264.7 cells to MP-1 at different concentrations. The effect of MP-1 on the viability of RAW264.7 cells was detected by MTT assay. Results MP-1 had high affinity to lipid A and could neutralize LPS. MP-1 at 10 μmol/L significantly inhibited not only binding of FITC-LPS to RAW264.7 (P < 0.05), but also protein and gene expressions of TLR4, TNF-α and IL-6 in LPS stimulated RAW264.7 cells in a dose-dependent manner (P < 0.05). No toxic effect of MP-1 on the viability of RAW264.7 cells was found (P > 0.05). Conclusions MP-1 inhibits cell viability mediated by LPS, which may be related to its neutralization of LPS and inhibition of binding of LPS to RAW264.7 cell membrane receptors.

Substances interfering with phosphatidyl inositol signalling pathway affect ultradian rhythm of Desmodium motorium.

The ultradian rhythm of the lateral leaflets of Desmodium motorium (Houtt.) Merril. was recorded with a picture analysis method using a video camera and a computer. The periods are in the minute range and depend strongly on temperature. The phosphatidyl inositol signal chain might be involved in the ultradian rhythm of the lateral leaflet movement of Desmodium motorium: Myoinositol shortens the period length and reduces the known period lengthening effect of lithium ions. Neomycin, which inhibits the hydrolysis of phosphatidylinositol-4, 5-biphosphate to inositol-4-phosphate and diacylglycerin, lengthens the period of the rhythm at low concentrations (0·2 mM). Higher concentrations shorten the period, perhaps by activating G protein. Mastoparan, which activates G protein, shortens period likewise. The G protein agonists fluorid ion and ethanol are toxic for the lateral leaflets and could therefore not be used to test the involvement of G protein. The intracellular Ca2+ antagonist 3, 4, 5-trinietlioxybeiizoic acid 8-(diethylamino)octylester lengthens the period of the rhythm. This indicates, that release of Ca2 + from intracellular stores is important for the lateral leaflet movement rhythm.

Effects of mastoparan on a vascular contractility in rabbit aorta

Mastoparan is an amphiphilic tetradecapeptide derived from wasp venom which activates G-proteins. Several secondary effects have been attributed to this peptide, including activation of phospholipase and phosphatidylinositol kinase. The aim of the present study was to investigate the effects of mastoparan on vascular contractility. Rabbit aortic rings were cut and mounted on a force transducer to record isometric tension on a polygraph. The effects of mastoparan were then investigated on the contractile responses in the isolated rabbit aorta with or without endothelium. The results were summarized as follows; 1. Mastoparan caused biphasic response, a transient relaxation followed by a further contraction, in norepinephrine (NE)-precontracted ring with endothelium. These effects were not observed in the aorta in the absence of endothelium. 2. Mastoparan-induced transient relaxation was significantly inhibited by treatment with a N-omega-nitro-L-arginine or methylene blue. 3. When an inhibitor of phospholipase C, neomycin was added to the precontracted aortic ring with NE, the transient relaxation induced by mastoparan was inhibited, but sustained contraction was not inhibited. 4. When an inhibitor of phospholipase A2, quinacrine and inhibitor of the cyclooxygenase pathway, indomethacin, were added to a precontracted ring with NE, the transient relaxation induced by mastoparan was not inhibited, but sustained contraction was inhibited. 5. Mastoparan induced a contraction of the aorta either with or without endothelium. Indomethacin and nifedipine inhibited mastoparan-induced contraction. From the above results, we concluded that mastoparan acts on the endothelium and modifies the release of endothelium-derived relaxing factors such as nitric oxide and also endothelium-derived contracting factors such as metabolites of arachidonic acid.