Peptides (v.29, #10)

Solution NMR structures of the antimicrobial peptides phylloseptin-1, -2, and -3 and biological activity: The role of charges and hydrogen bonding interactions in stabilizing helix conformations by Jarbas M. Resende; Cléria Mendonça Moraes; Maura V. Prates; Amary Cesar; Fabio C.L. Almeida; Nathália C.C.R. Mundim; Ana Paula Valente; Marcelo P. Bemquerer; Dorila Piló-Veloso; Burkhard Bechinger (1633-1644).
Phylloseptins are antimicrobial peptides of 19–20 residues which are found in the skin secretions of the Phyllomedusa frogs that inhabit the tropical forests of South and Central Americas. The peptide sequences of PS-1, -2, and -3 carry an amidated C-terminus and they exhibit 74% sequence homology with major variations of only four residues close to the C-terminus. Here we investigated and compared the structures of the three phylloseptins in detail by CD- and two-dimensional NMR spectroscopies in the presence of phospholipid vesicles or in membrane-mimetic environments. Both CD and NMR spectroscopies reveal a high degree of helicity in the order PS-2 ≥ PS-1 > PS-3, where the differences accumulate at the C-terminus. The conformational variations can be explained by taking into consideration electrostatic interactions of the negative ends of the helix dipoles with potentially cationic residues at positions 17 and 18. Whereas two are present in the sequence of PS-1 and -2 only one is present in PS-3. In conclusion, the antimicrobial phylloseptin peptides adopt alpha-helical conformations in membrane environments which are stabilized by electrostatic interactions of the helix dipole as well as other contributions such hydrophobic and capping interactions.
Keywords: Amphipathic α-helix; Antibiotic; Antifungal; Helix capping; Hydrogen bonds; Membrane interactions; Helix dipole;

Myotoxic phospholipases A2 isolated from Bothrops brazili snake venom and synthetic peptides derived from their C-terminal region: Cytotoxic effect on microorganism and tumor cells by Tassia R. Costa; Danilo L. Menaldo; Clayton Z. Oliveira; Norival A. Santos-Filho; Sabrina S. Teixeira; Auro Nomizo; André L. Fuly; Marta C. Monteiro; Bibiana M. de Souza; Mário S. Palma; Rodrigo G. Stábeli; Suely V. Sampaio; Andreimar M. Soares (1645-1656).
This paper reports the purification and biochemical/pharmacological characterization of two myotoxic phospholipases A2 (PLA2s) from Bothrops brazili venom, a native snake from Brazil. Both myotoxins (MTX-I and II) were purified by a single chromatographic step on a CM-Sepharose ion-exchange column up to a high purity level, showing M r  ∼ 14,000 for the monomer and 28,000 Da for the dimer. The N-terminal and internal peptide amino acid sequences showed similarity with other myotoxic PLA2s from snake venoms, MTX-I belonging to Asp49 PLA2 class, enzymatically active, and MTX-II to Lys49 PLA2s, catalytically inactive. Treatment of MTX-I with BPB and EDTA reduced drastically its PLA2 and anticoagulant activities, corroborating the importance of residue His48 and Ca2+ ions for the enzymatic catalysis. Both PLA2s induced myotoxic activity and dose–time dependent edema similar to other isolated snake venom toxins from Bothrops and Crotalus genus. The results also demonstrated that MTXs and cationic synthetic peptides derived from their 115–129 C-terminal region displayed cytotoxic activity on human T-cell leukemia (JURKAT) lines and microbicidal effects against Escherichia coli, Candida albicans and Leishmania sp. Thus, these PLA2 proteins and C-terminal synthetic peptides present multifunctional properties that might be of interest in the development of therapeutic strategies against parasites, bacteria and cancer.
Keywords: Cytotoxicity; Microbicide; Bothrops brazili; Synthetic peptides; Phospholipases A2; Myotoxins; Snake venom;

Human β-defensin (HBD)-2 is an inducible antimicrobial peptide that plays an important role in innate immunity. Induction of this peptide by mycobacteria in epithelial cells has been reported. However, the mechanism(s) by which Mycobacterium bovis bacillus Calmette-Guérin (BCG) triggers gene transcription of HBD-2 remains poorly understood. In the present work we found that treatment of human epithelial cells with Ro32-0432 or Gö6976, two selective inhibitors of protein kinase C (PKC), significantly reduced the effect of M. bovis BCG on induced HBD-2 mRNA expression (65 and 80% inhibition by 10 μM Ro32-0432, and 1 μM Gö6976 as assessed by real-time PCR, respectively). Moreover, there was increased activation of c-Jun N-terminal kinase (JNK) and phosphatidylinositol-3-kinase (PI3K)/Akt in A549 cells infected with M. bovis BCG, and this JNK and PI3K activation was mediated through PKC. Finally, we found that M. bovis BCG-induced HBD-2 mRNA gene expression in A549 cells was dependent on JNK, and PI3K determined by real-time PCR analysis, which was attenuated by inhibitors of JNK (SP600125 and AG126), and PI3K (wortmannin and Ly294002). These studies are the first to show that M. bovis BCG-induced HBD-2 mRNA expression in A549 cells is regulated at least in part through activation of signaling proteins of PKC, JNK and PI3K.
Keywords: Human β-defensin 2; Mycobacterium bovis BCG; PKC; JNK; PI3K;

The aim of this study was to purify and characterize antifungal peptides from kale seeds in view of the paucity of information on antifungal peptides from the family Brassicaceae, and to compare its characteristics with those of published Brassica antifungal peptides. A 5907-Da antifungal peptide was isolated from kale seeds. The isolation procedure comprised affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose and Mono S, and gel filtration on Superdex Peptide. The peptide was adsorbed on the first three chromatographic media. It inhibited mycelial growth in a number of fungal species including Fusarium oxysporum, Helminthosporium maydis, Mycosphaerella arachidicola and Valsa mali, with an IC50 of 4.3 μM, 2.1 μM, 2.4 μM, and 0.15 μM, respectively and exhibited pronounced thermostability and pH stability. It inhibited proliferation of hepatoma (HepG2) and breast cancer (MCF7) cells with an IC50 of 2.7 μM and 3.4 μM, and the activity of HIV-1 reverse transcriptase with an IC50 of 4.9 μM. Its N-terminal sequence differed from those of antifungal proteins which have been reported to date.
Keywords: Antifungal peptide; Kale; Seeds; Isolation; Antiproliferative; Thermostable;

Characterization of a novel vasopressin/oxytocin superfamily peptide and its receptor from an ascidian, Ciona intestinalis by Tsuyoshi Kawada; Toshio Sekiguchi; Yoshiyuki Itoh; Michio Ogasawara; Honoo Satake (1672-1678).
The vasopressin (VP)/oxytocin (OT) superfamily peptides are one of the most widely distributed neuropeptides and/or neurohypophysial hormones, but have ever not been characterized from any deuterostome invertebrates including protochordates, ascidians. In the present study, we show the identification of a novel VP/OT superfamily peptide and its receptor in the ascidian, Ciona intestinalis. Intriguingly, the Ciona VP/OT-related peptide (Ci-VP), unlike other 9-amino acid and C-terminally amidated VP/OT superfamily peptides, consists of 13 amino acids and lacks a C-terminal amidation. Mass spectrometry confirmed the presence of the 13-residue Ci-VP in the neural complex. Furthermore, 10 of 14 cysteines are conserved in the neurophysin domain, compared with other VP/OT counterparts. These results revealed that the VP/OT superfamily is conserved in ascidians, but the Ci-VP gene encodes an unprecedented VP/OT-related peptide and neurophysin protein. Ci-VP was also shown to activate its endogenous receptor, Ci-VP-R, at physiological concentrations, confirming the functionality of Ci-VP as an endogenous ligand. The Ci-VP gene was expressed exclusively in neurons of the brain, whereas the Ci-TK-R mRNA was distributed in various tissues including the neural complex, alimentary tract, gonad, and heart. These expression profiles suggest that Ci-VP, like other VP/OT superfamily peptides, serves as a multifunctional neuropeptides. Altogether, our data revealed both evolutionary conservation and specific divergence of the VP/OT superfamily in protochordates. This is the first molecular characterization of a VP/OT superfamily peptide and its cognate receptor from not only ascidians but also deuterostome invertebrates.
Keywords: Vasopressin; Oxytocin; Ascidian; Ciona intestinalis; GPCR; Neurophysin;

Genomic organization and cloning of novel genes encoding toxin-like peptides of three superfamilies from the spider Orinithoctonus huwena by Liping Jiang; Jinjun Chen; Li Peng; Yongqun Zhang; Xia Xiong; Songping Liang (1679-1684).
The bird spider Ornithoctonus huwena is one of the most venomous spiders in China. Its venom is a mixture of various compounds with diverse bioactivities. Ninety proteins and 47 peptides have been identified, and 67 cDNA sequences encoding different toxin precursors have been cloned. However, the genomic DNA of them is seldom reported. To characterize the genomic DNA structure of huwentoxins, the genomic DNA encoding toxins of three superfamilies were cloned by using sequence specific or partially degenerate primers based on their cDNA sequences. An unexpected finding was that the intron was lacking in the genomic sequences of three superfamilies. The genomic DNA information has predictive value for better understanding the relationship of spider toxin evolution. In addition, we have cloned and analyzed 19 novel genes encoding toxin-like precursors by using the genomic DNA of the spider O. huwena.
Keywords: Ornithoctonus huwena; Spider; Intron; Genomic organization; Toxin-like peptide;

Identification and characterization of novel reptile cathelicidins from elapid snakes by Hui Zhao; Tong-Xiang Gan; Xiao-Dong Liu; Yang Jin; Wen-Hui Lee; Ji-Hong Shen; Yun Zhang (1685-1691).
Three cDNA sequences coding for elapid cathelicidins were cloned from constructed venom gland cDNA libraries of Naja atra, Bungarus fasciatus and Ophiophagus hannah. The open reading frames of the cloned elapid cathelicidins were all composed of 576 bp and coded for 191 amino acid residue protein precursors. Each of the deduced elapid cathelicidin has a 22 amino acid residue signal peptide, a conserved cathelin domain of 135 amino acid residues and a mature antimicrobial peptide of 34 amino acid residues. Unlike the highly divergent cathelicidins in mammals, the nucleotide and deduced protein sequences of the three cloned elapid cathelicidins were remarkably conserved. All the elapid mature cathelicidins were predicted to be cleaved at Valine157 by elastase. OH-CATH, the deduced mature cathelicidin from king cobra, was chemically synthesized and it showed strong antibacterial activity against various bacteria with minimal inhibitory concentration of 1–20 μg/ml in the presence of 1% NaCl. Meanwhile, the synthetic peptide showed no haemolytic activity toward human red blood cells even at a high dose of 200 μg/ml. Phylogenetic analysis of cathelicidins from vertebrate suggested that elapid and viperid cathelicidins were grouped together in the tree. Snake cathelicidins were evolutionary closely related to the neutrophilic granule proteins (NGPs) from mouse, rat and rabbit. Snake cathelicidins also showed a close relationship with avian fowlicidins (1–3) and chicken myeloid antimicrobial peptide 27. Elapid cathelicidins might be used as models for the development of novel therapeutic drugs.
Keywords: Antimicrobial peptide; Cathelicidin; Elapid snake; Molecular cloning; Phylogenetic analysis;

Isolation, expression and characterization of a novel dual serine protease inhibitor, OH-TCI, from king cobra venom by Ying-Ying He; Shu-Bai Liu; Wen-Hui Lee; Jin-Qiao Qian; Yun Zhang (1692-1699).
Snake venom Kunitz/BPTI members are good tools for understanding of structure–functional relationship between serine proteases and their inhibitors. A novel dual Kunitz/BPTI serine proteinase inhibitor named OH-TCI (trypsin- and chymotrypsin-dual inhibitor from Ophiophagus hannah) was isolated from king cobra venom by three chromatographic steps of gel filtration, trypsin affinity and reverse phase HPLC. OH-TCI is composed of 58 amino acid residues with a molecular mass of 6339 Da. Successful expression of OH-TCI was performed as the maltose-binding fusion protein in E. coli DH5α. Much different from Oh11-1, the purified native and recombinant OH-TCI both had strong inhibitory activities against trypsin and chymotrypsin although the sequence identity (74.1%) between them is very high. The inhibitor constants (K i) of recombinant OH-TCI were 3.91 × 10−7 and 8.46 × 10−8  M for trypsin and chymotrypsin, respectively. To our knowledge, it was the first report of Kunitz/BPTI serine proteinase inhibitor from snake venom that had equivalent trypsin and chymotrypsin inhibitory activities.
Keywords: Serine proteinase inhibitor; Chymotrypsin inhibitor; Trypsin inhibitor; Snake venom; Kunitz/BPTI family polypeptide; King cobra;

α4/7-conotoxin Lp1.1 is a novel antagonist of neuronal nicotinic acetylcholine receptors by Can Peng; Yuhong Han; Tanya Sanders; Geoffrey Chew; Jing Liu; Edward Hawrot; Chengwu Chi; Chunguang Wang (1700-1707).
Cone snails comprise approximately 700 species of venomous molluscs which have evolved the ability to generate multiple toxins with varied and exquisite selectivity. α-Conotoxin is a powerful tool for defining the composition and function of nicotinic acetylcholine receptors which play a crucial role in excitatory neurotransmission and are important targets for drugs and insecticides. An α4/7 conotoxin, Lp1.1, originally identified by cDNA and genomic DNA cloning from Conus leopardus, was found devoid of the highly conserved Pro residue in the first intercysteine loop. To further study this toxin, α-Lp1.1 was chemically synthesized and refolded into its globular disulfide isomer. The synthetic Lp1.1 induced seizure and paralysis on freshwater goldfish and selectively reversibly inhibited ACh-evoked currents in Xenopus oocytes expressing rat α3β2 and α6α3β2 nAChRs. Comparing the distinct primary structure with other functionally related α-conotoxins could indicate structural features in Lp1.1 that may be associated with its unique receptor recognition profile.
Keywords: Conus; α-Conotoxins; Neuronal nicotinic acetylcholine receptor subtypes; Xenopus oocytes;

A novel physiological property of snake bradykinin-potentiating peptides—Reversion of MK-801 inhibition of nicotinic acetylcholine receptors by Arthur A. Nery; Cleber A. Trujillo; Claudiana Lameu; Katsuhiro Konno; Vitor Oliveira; Antonio C.M. Camargo; Henning Ulrich; Mirian A.F. Hayashi (1708-1715).
The first naturally occurring angiotensin-converting enzyme (ACE) inhibitors described are pyroglutamyl proline-rich oligopeptides, found in the venom of the viper Bothrops jararaca, and named as bradykinin-potentiating peptides (BPPs). Biochemical and pharmacological properties of these peptides were essential for the development of Captopril, the first active site-directed inhibitor of ACE, currently used for the treatment of human hypertension. However, a number of data have suggested that the pharmacological activity of BPPs could not only be explained by their inhibitory action on enzymatic activity of somatic ACE. In fact, we showed recently that the strong and long-lasting anti-hypertensive effect of BPP-10c [<ENWPHPQIPP] is independent of somatic ACE inhibition. On the other hand, nicotinic acetylcholine receptors expressed in blood vessels have been related to blood pressure regulation. Therefore, we have studied the effects of BPP-10c on acetylcholine receptor function in the PC12 pheochromocytoma cell line, which following induction to neuronal differentiation expresses most of the nicotinic receptor subtypes. BPP-10c did not induce receptor-mediated ion flux, nor potentiated carbamoylcholine-provoked receptor activity as determined by whole-cell recording. This peptide, however, alleviated MK-801-induced inhibition of nicotinic acetylcholine receptor activity. Although more data are needed for understanding the mechanism of the BPP-10c effect on nicotinic receptor activity and its relationship with the anti-hypertensive activity, this work reveals possible therapeutic applications for BPP-10c in establishing normal acetylcholine receptor activity.
Keywords: Bradykinin-potentiating peptides; Nicotinic acetylcholine receptor; MK-801 inhibition; PC12 pheochromocytoma cells;

Mechanisms of action of CCK to activate central vagal afferent terminals by Richard C. Rogers; Gerlinda E. Hermann (1716-1725).
Cholecystokinin [CCK] is a peptide released as a hormone by the proximal gut in response to the presence of peptones and fatty acid in the gut. Considerable evidence suggests that CCK inhibits feeding behavior and gastric function by acting as a paracrine modulator of vagal afferents in the periphery, especially in the duodenum. CCK is also widely distributed throughout the mammalian brain and appears to function as a neurotransmitter and neuromodulator. More recent studies have suggested that CCK may act directly within the CNS to activate central vagal afferent terminal inputs to the solitary nucleus. We have developed an in vitro calcium imaging method that reveals, for the first time, the direct effects of this peptide on vagal terminals in the solitary nucleus. In vitro imaging reveals that CCK provokes increases in intracellular calcium in vagal afferent terminals as a consequence of a complex interaction between protein kinase A [PKA] and phospholipase C [PLC] transduction mechanisms that open L-type calcium channels and causes endoplasmic reticular [ER] calcium release. The subsequent activation of PKC may be responsible for initiating calcium spiking which is dependent on a TTX-sensitive mechanism. Thus, imaging of the isolated but spatially intact hindbrain slice has allowed a more complete appreciation of the interdependent transduction mechanisms used by CCK to excite identified central vagal afferent fibers and varicosities.
Keywords: Calcium imaging; Satiety; Hindbrain;

Effects of an antagonist of the bombesin/gastrin-releasing peptide receptor on complete Freund's adjuvant-induced arthritis in rats by P.G. Oliveira; C.V. Brenol; M.I. Edelweiss; J.C.T. Brenol; F. Petronilho; R. Roesler; F. Dal-Pizzol; G. Schwartsmann; R.M. Xavier (1726-1731).
Objective: To determine the effects of RC-3095 in clinical and histopathologic parameters and inflammatory mediators on complete Freund's adjuvant-induced arthritis (CFA). Methods: The arthritis was induced by injection of CFA into the left hind footpad. The animals were divided into control, vehicle injected control, placebo group (saline subcutaneously 50 ml/kg, once daily for 8 days after modeling), treatment group (0.3 mg/kg of RC-3095 subcutaneously, once daily for 8 days after induction). Clinical evaluation was accomplished daily, through scoring of the paw edema. The animals were sacrificed 15 days after induction for collection of hind foot joints for histology. We used a histological scoring system which was previously described, and interferon (INF)-γ, interleukin (IL)-1β, tumor necrosis factor (TNF), interleukin (IL)-6 and interleukin (IL)-10 were measured by ELISA. Results: There was a significant inhibition of joint histological findings in the RC-3095 treated group, including synovial inflammatory infiltration and hyperplasia, cartilage and bone erosion. IFN-γ, IL-1β, TNF, IL-6 and IL-10 serum levels were significantly lower in the treated group. Paw swelling and subcutaneous inflammation, evaluated clinically, were not different between CFA-induced groups. Conclusions: RC-3095 was able to improve experimental arthritis, attenuate joint damage and decrease serum levels of IFN-γ, IL-1β, TNF, IL-6 and IL-10. These data indicate that interference with GRP pathway is a potential new strategy for the treatment of RA that needs further investigational studies.
Keywords: Animal model; Synovitis; Complete Freund's adjuvant; Gastrin-releasing peptide; RC-3095;

Neuropeptide Y (NPY) conjugated with a ribosomal inactivating toxin, saporin (SAP), is a toxin that targets NPY receptor-expressing cells. Injection of NPY–SAP into the rat arcuate nucleus (Arc) and basomedial hypothalamus (BMH) destroys two populations of NPY-receptor-expressing neurons important for the control of food intake and body weight, NPY and pro-opiomelanocortin (POMC) and cocaine and amphetamine related transcript (CART) neurons, and produces profound hyperphagia and obesity. Here, we investigated the contribution of lateral hypothalamus (LHA) orexigenic peptides, orexins and melanocortin concentrating hormone (MCH), to these lesion effects. We microinjected NPY–SAP into two sites on each side of the Arc, causing a loss of NPY and POMC/CART neurons that was limited to the Arc. Lesioned rats rapidly became hyperphagic and obese. However, MCH and prepro-orexin mRNA expression were not increased in the LHA in the lesioned rats, but were decreased at some levels of the LHA or were unchanged. NPY–SAP-induced obesity therefore differs from dietary obesity and from obesity associated with leptin or leptin receptor deficiency in which MCH gene expression is increased. The Arc NPY–SAP lesion produces obesity and hyperphagia that does not require overexpression of hypothalamic neuropeptides currently considered to provide major stimulatory drive for food intake: NPY, agouti gene-related protein, MCH or orexins. The source of the seemingly unregulated stimulatory drive for feeding in these animals has not been identified, but may be associated with hindbrain or endocrine mechanisms.
Keywords: Saporin; Arcuate nucleus; MCH; Orexins; LHA; Rats;

In vitro metabolic stability of obestatin: Kinetics and identification of cleavage products by Valentijn Vergote; Sylvia Van Dorpe; Kathelijne Peremans; Christian Burvenich; Bart De Spiegeleer (1740-1748).
The in vitro metabolic stability testing on synthetic obestatin peptides from two different species (human hOb and mouse mOb) using HPLC analysis is described. A reversed-phase C18 column of 300 Å pore size was used, with a gradient system based on aqueous formic acid and acetonitrile. Electrospray ionization (ESI) ion trap mass spectrometry was used for identification of the chromatographic eluting peptide metabolic products, while UV (DAD) and fluorescence served quantitative purposes. Differences in the metabolic degradation kinetics of hOb and mOb were found in plasma, liver and kidney homogenate, with half-lives ranging between 12.6 and 138.0 min. Proteolytic hydrolysis at the N-terminal Phe residue and cleavage at Pro4–Phe5 were found to be two major metabolic pathways, accounting for more than 50% of the metabolic degradation. Several other labile peptide bonds were located. The influence of a standard protease inhibitor cocktail was investigated, as well as the metabolism of iodinated human obestatin in liver homogenate. Our results indicate that the major instability of obestatin peptides, as currently used in biomedical investigations, should be taken into account in the interpretation of the obtained results.
Keywords: Obestatin metabolites; Peptide catabolism; Proteolytic activity; Cleavage sites; HPLC-PDA; Fluorescence; ESI-ion trap MS/MS; In vitro degradation of peptides; Protease inhibitors; Peptidomimetics;

Plasma obestatin levels in men with chronic atrophic gastritis by Xin-Yuan Gao; Hong-Yu Kuang; Xiao-Min Liu; Zhi-Bin Ma; Hao-Jie Nie; Hong Guo (1749-1754).
Obestatin is a recently discovered active peptide isolated from the stomach. The purpose of the present study was to investigate the modification of plasma obestatin levels in men with chronic atrophic gastritis. Men older than 65 years undergoing upper gastrointestinal endoscopy were included. All patients with chronic atrophic gastritis underwent multiple biopsies. Fasting plasma obestatin and ghrelin levels were examined in 50 men with chronic atrophic gastritis and 50 healthy men. Plasma obestatin levels were significantly lower in patients with chronic atrophic gastritis than in healthy subjects. Plasma ghrelin levels and ghrelin to obestatin ratio was decreased in men with chronic atrophic gastritis. There was a significant relationship between atrophy and decreased obestatin. A negative correlation was found between circulating obestatin levels and body mass index (BMI) in healthy subjects, but not in patients with chronic atrophic gastritis. The data indicated that chronic atrophic gastritis influenced plasma obestatin levels as well as ghrelin to obestatin ratio in elderly men.
Keywords: Obestatin; Ghrelin; Chronic atrophic gastritis; Radioimmunoassay;

Massive peptide sharing between viral and human proteomes by Darja Kanduc; Angela Stufano; Guglielmo Lucchese; Anthony Kusalik (1755-1766).
Thirty viral proteomes were examined for amino acid sequence similarity to the human proteome, and, in parallel, a control of 30 sets of human proteins was analyzed for internal human overlapping. We find that all of the analyzed 30 viral proteomes, independently of their structural or pathogenic characteristics, present a high number of pentapeptide overlaps to the human proteome. Among the examined viruses, human T-lymphotropic virus 1, Rubella virus, and hepatitis C virus present the highest number of viral overlaps to the human proteome. The widespread and ample distribution of viral amino acid sequences through the human proteome indicates that viral and human proteins are formed of common peptide backbone units and suggests a fluid compositional chimerism in phylogenetic entities canonically classified distantly as viruses and Homo sapiens. Importantly, the massive viral to human peptide overlapping calls into question the possibility of a direct causal association between virus–host sharing of amino acid sequences and incitement to autoimmune reactions through molecular recognition of common motifs.
Keywords: Viral proteomes; Human proteome; Sequence similarity; Peptide sharing; Autoimmunity;

Hyper-responsiveness of adrenal gland to vasopressin resulting in enhanced plasma cortisol in patients with adrenal nodule(s) by Sawako Suzuki; Daigaku Uchida; Hisashi Koide; Tomoaki Tanaka; Yoshihiko Noguchi; Yasushi Saito; Ichiro Tatsuno (1767-1772).
Hyper-responsiveness of plasma cortisol to vasopressin has been demonstrated in ACTH-independent bilateral macronodular adrenocortical hyperplasia (AIMAH) and some adrenal adenomas with Cushing's syndrome (CS). However, the clinical significance of hyper-responsiveness of plasma cortisol to vasopressin has not been investigated systematically in adrenal nodule(s). The aim of this study was to clarify the prevalence of hyper-responsiveness of plasma cortisol to vasopressin (vasopressin responder) and their clinical characteristics in terms of hormonal secretion using vasopressin-loading test in the patients with adrenal nodule(s) except pheochromocytomas. A vasopressin-loading test was performed on 61 consecutive patients with adrenal nodules (CS: 33, aldosterone-producing adenoma: 10, non-functional tumor: 18). Vasopressin responders were observed in 36.1% of adrenal nodule(s), 42.4% of CS and 28.5% of non-CS. In responders with CS, eight patients had bilateral nodules that were diagnosed as AIMAH, and the remaining six patients had a unilateral nodule. These patients had lower plasma cortisol than non-responders at both morning (P  < 0.01) and midnight (P  < 0.05), as well as the morning following overnight dexamethasone suppression at 1 mg (P  < 0.05) and 8 mg (P  < 0.05). Hyper-responsiveness of the adrenal gland to vasopressin resulting in enhanced plasma cortisol was frequently observed among patients with adrenal nodule(s). The vasopressin responders among the patients with adrenal nodule(s) frequently had CS with low autonomous cortisol secretion.
Keywords: Vasopressin; Adrenal nodules; Cushing's syndrome; V1a receptor;

Angiotensin II is known to act primarily on the angiotensin AT1 receptors to mediate its physiological and pathological actions. Des-aspartate-angiotensin I (DAA-I) is a bioactive angiotensin peptide and have been shown to have contrasting vascular actions to angiotensin II. Previous work in this laboratory has demonstrated an overwhelming vasodepressor modulation on angiotensin II-induced vasoconstriction by DAA-I. The present study investigated the involvement of the AT1 receptor in the actions of DAA-I on angiotensin II-induced vascular actions in the renal vasculature of normotensive Wistar–Kyoto rats (WKY), spontaneously hypertensive rats (SHR) and streptozotocin (STZ)-induced diabetic rats. The findings revealed that the angiotensin receptor in rat kidney homogenate was mainly of the AT1 subtype. The AT1 receptor density was significantly higher in the kidney of the SHR. The increase in AT1 receptor density was also confirmed by RT-PCR and Western blot analysis. In contrast, AT1 receptor density was significantly reduced in the kidney of the streptozotocin-induced diabetic rat. Perfusion with 10−9  M DAA-I reduced the AT1 receptor density in the kidneys of WKY and SHR rats suggesting that the previously observed vasodepressor modulation of the nonapeptide could be due to down-regulation or internalization of AT1 receptors. RT-PCR and Western blot analysis showed no significant changes in the content of AT1 receptor mRNA and protein. This supports the suggestion that DAA-I causes internalization of AT1 receptors. In the streptozotocin-induced diabetic rat, no significant changes in renal AT1 receptor density and expression were seen when its kidneys were similarly perfused with DAA-I.
Keywords: Angiotensin subtype 1 receptor; Des-aspartate angiotensin I; Renal vasculature; Streptozotocin-induced diabetes; Spontaneously hypertensive rat;

Calcitonin gene-related peptide-mediated antihypertensive and anti-platelet effects by rutaecarpine in spontaneously hypertensive rats by Dai Li; Jun Peng; Hong-Ya Xin; Dan Luo; Yi-Shuai Zhang; Zhi Zhou; De-Jian Jiang; Han-Wu Deng; Yuan-Jian Li (1781-1788).
We have previously reported that Chinese traditional medicine rutaecarpine (Rut) produced a sustained hypotensive effect in phenol-induced and two-kidney, one-clip hypertensive rats. The aims of this study are to determine whether Rut could exert antihypertensive and anti-platelet effects in spontaneously hypertensive rats (SHR) and the underlying mechanisms. In vivo, SHR were given Rut and the blood pressure was monitored. Blood was collected for the measurements of calcitonin gene-related peptide (CGRP), tissue factor (TF) concentration and activity, and platelet aggregation, and the dorsal root ganglia were saved for examining CGRP expression. In vitro, the effects of Rut and CGRP on platelet aggregation were measured, and the effect of CGRP on platelet-derived TF release was also determined. Rut exerted a sustained hypotensive effect in SHR concomitantly with the increased synthesis and release of CGRP. The treatment of Rut also showed an inhibitory effect on platelet aggregation concomitantly with the decreased TF activity and TF antigen level in plasma. Study in vitro showed an inhibitory effect of Rut on platelet aggregation in the presence of thoracic aorta, which was abolished by capsazepine or CGRP(8–37), an antagonist of vanilloid receptor or CGRP receptor. Exogenous CGRP was able to inhibit both platelet aggregation and the release of platelet-derived TF, which were abolished by CGRP(8–37). The results suggest that Rut exerts both antihypertensive and anti-platelet effects through stimulating the synthesis and release of CGRP in SHR, and CGRP-mediated anti-platelet effect is related to inhibiting the release of platelet-derived TF.
Keywords: Calcitonin gene-related peptide; Rutaecarpine; Spontaneously hypertensive rats; Blood pressure; Tissue factor; Platelet aggregation;

A new pentapeptide compound, PLNPK, ameliorates anti-glomerular basement membrane nephritis in Wistar rats by Chun-lei Zhou; Jun-qiang Lv; Rong Lu; Li-juan Chen; Hui-qiang Li; Hui-ling Cao; Qiu-li Li; Song Wang; Zheng Fu; Zhi Yao (1789-1797).
PLNPK is a pentapeptide compound extracted from pig spleen with a Pro-Leu-Asn-Pro-Lys molecular structure. The spleen is the biggest immune organ in the body, in which there are lots of immunocytes and immune molecules. Our pilot study showed that PLNPK could suppress the transformation and proliferation of T lymphocytes and the production of antibodies in mice. It is widely accepted that most types of glomerulonephritis are immunological diseases caused by the reaction of antigen and antibody. Both humoral immunity and cell-mediated immunity contribute to the progress of these diseases, and suppression of immunoreactions and inflammation is important to ameliorate nephritis. After the immunosuppressive effects of this compound were discovered, this study also examined whether PLNPK had beneficial effects on a rat model of glomerulonephritis. The results suggested PLNPK (200 μg/kg/d and 400 μg/kg/d) reduced urinary protein excretion, lessened the deposit of autoantibodies along the glomerular basement membrane (GBM), reduced formation of crescent and protein casts, and ameliorated glomerular fibrosis and GBM injury. After treatment with PLNPK (200 μg/kg/d and 400 μg/kg/d) for 7 days, macrophage infiltration in the glomeruli was markedly reduced. Our results suggest that PLNPK has a beneficial effect on rat anti-GBM nephritis.
Keywords: Pentapeptide; PLNPK; Anti-glomerular basement membrane nephritis; Macrophage; Rat;

New descriptors of amino acids and their application to peptide QSAR study by Zhi-hua Lin; Hai-xia Long; Zhu Bo; Yuan-qiang Wang; Yu-zhang Wu (1798-1805).
A new set of descriptors was derived from a matrix of three structural variables of the natural amino acid, including van der Waal's volume, net charge index and hydrophobic parameter of side residues. They were selected from many properties of amino acid residues, which have been validated being the key factors to influence the interaction between peptides and its protein receptor. They were then applied to structure characterization and QSAR analysis on bitter tasting di-peptide, agiotensin-converting enzyme inhibitor and bactericidal peptides by using multiple linear regression (MLR) method. The leave one out cross validation values (Q 2) were 0.921, 0.943 and 0.773. The multiple correlation coefficients (R 2) were 0.948, 0.970 and 0.926, the root mean square (RMS) error for estimated error were 0.165, 0.154 and 0.41, respectively for bitter tasting di-peptide, angiotensin-converting enzyme inhibitor and bactericidal peptides. Test sets of peptides were used to validate the quantitative model, and it was shown that all these QSAR models had good predictability for outside samples. The results showed that, in comparison with the conventional descriptors, the new set of descriptors is a useful structure characterization method for peptide QSAR analysis, which has multiple advantages, such as definite physical and chemical meaning, easy to get, and good structural characterization ability.
Keywords: Peptide; Structure parameterization; Multiple linear regression; Quantitative structure–activity relationship;

Antinociceptive effect of the C-terminus of murine S100A9 protein on experimental neuropathic pain by Carina Cicconi Paccola; Vanessa Pacciari Gutierrez; Ingrid Longo; Luiz Juliano; Maria Aparecida Juliano; Renata Giorgi (1806-1814).
The synthetic peptide identical to the C-terminus of murine S100A9 protein (mS100A9p) has antinociceptive effect on different acute inflammatory pain models. In this study, the effect of mS100A9p was investigated on neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve in rats. Hyperalgesia, allodynia, and spontaneous pain were assessed to evaluate nociception. These three signs were detected as early as 2 days after sciatic nerve constriction and lasted for over 14 days after CCI. Rats were treated with different doses of mS100A9p by intraplantar, oral, or intrathecal routes on day 14 after CCI, and nociception was evaluated 1 h later. These three routes of administration blocked hyperalgesia, allodynia and spontaneous pain. The duration of the effect of mS100A9p depends on the route used and phenomenon analyzed. Moreover, intraplantar injection of mS100A9p in the contralateral paw inhibited the hyperalgesia on day 14 days after CCI. The results obtained herein demonstrate the antinociceptive effect of the C-terminus of murine S100A9 protein on experimental neuropathic pain, suggesting a potential therapeutic use for it in persistent pain syndromes, assuming that tolerance does not develop to mS100A9p.
Keywords: Neuropathic pain; S100A9; Antinociception; Sciatic nerve; Chronic constriction injury;

Endomorphins interact with the substance P (SP) aminoterminal SP1–7 binding in the ventral tegmental area of the rat brain by Milad Botros; Tobias Johansson; Qin Zhou; Gunnar Lindeberg; Csaba Tömböly; Géza Tóth; Pierre Le Grevès; Fred Nyberg; Mathias Hallberg (1820-1824).
We have recently identified a specific binding site for the tachykinin peptide substance P (SP) fragment SP1–7 in the rat spinal cord. This site appeared very specific for SP1–7 as the binding affinity of this compound highly exceeded those of other SP fragments. We also observed that endomorphin-2 (EM-2) exhibited high potency in displacing SP1–7 from this site. In the present work using a [3H]-labeled derivative of the heptapeptide we have identified and characterized [3H]-SP1–7 binding in the rat ventral tegmental area (VTA). Similarly to the [3H]-SP1–7 binding in the spinal cord the affinity of unlabeled SP1–7 to the specific site in VTA was significantly higher than those of other SP fragments. Further, the tachykinin receptor NK-1, NK-2 and NK-3 ligands showed no or negligible binding to the identified site. However, the μ-opioid peptide (MOP) receptor agonists DAMGO, EM-1 and EM-2 did, and significant difference was observed in the binding affinity between the two endomorphins. As recorded from displacement curves the affinity of EM-2 for the SP1–7 site was 4–5 times weaker than that for SP1–7 but about 5 times higher than that of EM-1. The opioid receptor antagonists naloxone and naloxonazine showed weak or negligible binding. It was concluded that the specific site identified for SP1–7 binding in the rat VTA is distinct from the MOP receptor although it exhibits high affinity for EM-2.

Role of α-melanocyte stimulating hormone and melanocortin 4 receptor in brain inflammation by Mercedes Lasaga; Luciano Debeljuk; Daniela Durand; Teresa N. Scimonelli; Carla Caruso (1825-1835).
Inflammatory processes contribute widely to the development of neurodegenerative diseases. The expression of many inflammatory mediators was found to be increased in central nervous system (CNS) disorders suggesting that these molecules are major contributors to neuronal damage. Melanocortins are neuropeptides that have been implicated in a wide range of physiological processes. The melanocortin alpha-melanocyte stimulating hormone (α-MSH) has pleiotropic functions and exerts potent anti-inflammatory actions by antagonizing the effects of pro-inflammatory cytokines and by decreasing important inflammatory mediators. Five subtypes of melanocortin receptors (MC1R-MC5R) have been identified. Of these, the MC4 receptor is expressed predominantly throughout the CNS. Evidence of effectiveness of selective MC4R agonists in modulating inflammatory processes and their low toxicity suggest that these molecules may be useful in the treatment of CNS disorders with an inflammatory component. This review describes the involvement of the MC4R in central anti-inflammatory effects of melanocortins and discusses the potential value of MC4R agonists for the treatment of inflammatory-related disorders.
Keywords: Inflammation; CNS; α-MSH; MC4 receptor;

Worldwide, tuberculosis remains the most important infectious disease causing morbidity and death. Currently, at least one-third of the world's population is infected with Mycobacterium tuberculosis. In addition, the World Health Organization estimates that about 8–10 million new tuberculosis cases occur annually worldwide and this incidence is currently increasing. Moreover, multidrug-resistant tuberculosis has been increasing in incidence in many areas during the past decade. These situations underscore the importance of the development of new therapeutic agents against mycobacterial infectious diseases. In this article, it is review current progress in the understanding of antimicrobial peptides as potential candidates to develop an alternative/adjunct therapeutic strategy against tuberculosis. This immunoadjunctive therapy might be evaluated in the context of possible drug resistance. This review also summarizes the knowledge about the functions of antimicrobial peptides in the pulmonary innate host defense system and their role in mycobacterial infection, and at the same time outlines recent advances in our understanding of the combined effect of antimicrobial peptides and anti-tuberculosis drugs against intracellular mycobacteria. A concerted effort should now focus on the clinical application of antimicrobial peptides for their practical use.
Keywords: Antimicrobial peptides; Innate immunity; Mycobacteria; Tuberculosis;

Biotechnological potential of antimicrobial peptides from flowers by Letícia S. Tavares; Marcelo de O. Santos; Lyderson F. Viccini; João S. Moreira; Robert N.G. Miller; Octávio L. Franco (1842-1851).
Flowers represent a relatively unexplored source of antimicrobial peptides of biotechnological potential. This review focuses on flower-derived defense peptide classes with inhibitory activity towards plant pathogens. Small cationic peptides display diverse activities, including inhibition of digestive enzymes and bacterial and/or fungal inhibition. Considerable research is ongoing in this area, with natural crop plant defense potentially improved through the application of transgenic technologies. In this report, comparisons were made of peptide tertiary structures isolated from diverse flower species. A summary is provided of molecular interactions between flower peptides and pathogens, which include the role of membrane proteins and lipids. Research on these peptides is contributing to our understanding of pathogen resistance mechanisms, which will, given the perspectives for plant genetic modification, contribute long term to plant genetic improvement for increased resistance to diverse pathogens.
Keywords: Flowers; Antimicrobial peptides; Defensins; Snakins; Plant defense;