Peptides (v.21, #9)

Prevention of diseases caused by Staphylococcus aureus using the peptide RIP by Naomi Balaban; L.Vincent Collins; James S Cullor; Emma B Hume; Enrique Medina-Acosta; Olney Vieira da Motta; Richard O’Callaghan; Paul V Rossitto; Mark E Shirtliff; Leonardo Serafim da Silveira; Andrej Tarkowski; Jose V Torres (1301-1311).
Staphylococcus aureus causes many diseases including cellulitis, keratitis, osteomyelitis, septic arthritis and mastitis. The heptapeptide RIP has been shown to prevent cellulitis in mice, which was induced by S. aureus strain Smith diffuse. Here we show that RIP can also significantly reduce the overall pathology and delay the onset of disease symptoms in several other models of S. aureus infections, including: keratitis (tested in rabbits against S. aureus 8325–4), osteomyelitis (tested in rabbits against S. aureus MS), mastitis (tested in cows against S. aureus Newbould 305, AE-1, and environmental infections) and septic arthritis (tested in mice against S. aureus LS-1). These findings substantiate that RIP is not strain specific in its inhibitory activity and that RIP is an effective inhibitor of bacterial pathology at multiple body sites following diverse routes and doses of administration. These findings strongly evidence the potential value of RIP as a chemotherapeutic agent.

We have isolated a peptide from extracts of sinus glands from a South African spiny lobster species, Jasus lalandii, by high-performance liquid chromatography (HPLC) and identified it as a putative molt-inhibiting hormone (MIH) by (i) an in vitro assay with J. lalandii Y-organs to measure the inhibition of ecdysteroid synthesis and (ii) an immunoassay using antiserum raised against MIH of the edible crab. The MIH of J. lalandii has 74 amino acid residues, a molecular mass of 9006 Da, a free N-terminus and an amidated C-terminus. The full primary sequence has been obtained from sequencing various digest fragments (tryptic, endoproteinase Asp-N, cyanogen bromide) of the unreduced (native) peptide: RFTFDCPGMMGQRYLYEQVEQVCDDCYNLYREEKIAVNCRENCFLNSWFTVCLQATMREHETPRFDIWRSIILKA-NH2. Structural comparisons with other peptides show that the J. lalandii MIH belongs to the peptide family which includes the crustacean hyperglycemic hormone, molt-inhibiting hormone and vitellogenesis-inhibiting hormone (cHH/MIH/VIH). This novel peptide has 36–43% sequence identity to putative MIHs from other decapod crustaceans and 32–34% identity to the two cHH peptides previously identified in this spiny lobster species. This is the first report of a peptide with MIH activity in the Palinuridae infraorder.
Keywords: Molt-inhibiting hormone; Neuropeptide; Crustacean; Jasus lalandii; Spiny lobster; Sinus gland; Y-organ; Ecdysteroid synthesis;

We investigated whether neuropeptides which control sexual differentiation in mollusks can induce imposex—a condition where female snails grow male accessory sex organs after exposure to tributyltin (TBT). Mud snails, Ilyanassa obsoleta, were dosed with one of four neuropeptides: APGWamide, conopressin, LSSFVRIamide, or FMRFamide for seven or fourteen days. TBT and testosterone (T) were used as positive controls and induced imposex as expected. APGWamide significantly induced imposex, with a threshold dose near 10 16 moles. The other neuropeptides had no effect on imposex induction. We propose that TBT could act as a neurotoxin to induce imposex via abnormal release of APGWamide.
Keywords: Imposex; TBT; Neuropeptides; Testosterone; Mud snail; Sexual differentiation;

Effects of L-thyrosyl - L-arginine (kyotorphin) on the behavior of rats and goldfish by S.G Kolaeva; T.P Semenova; I.M Santalova; D.A Moshkov; I.A Anoshkina; V Golozubova (1331-1336).
The effects of kyotorphin (KTP), a dipeptide (L-Tyr-L-Arg), on the level of sensory attention to stimuli of different modalities in rats and the exploratory behavior in goldfish were investigated. In both cases KTP was found to suppress the exploratory activity. When 5-HTP, a precursor of serotonin synthesis, is activated the inhibitory effects of KTP increased. It is assumed that the regulatory effect of KTP on the exploratory behavior of animals is mediated by the monoaminergic (neurotransmitting) brain systems, as distinct from its analgetic effects, which are mediated by the opioid brain systems.
Keywords: Exploratory behavior; Rat; Goldfish; Kyotorphin; Serotonin;

The cDNAs encoding the preprohormones of the regulatory peptides cholecystokinin (CCK) and the related gastrin have been identified in a number of vertebrate species. However, from birds only chicken preprogastrin is known. In the present study preproCCK cDNA was identified in two species of birds, ostrich and chicken. In addition, the molecular forms of the bioactive peptides expressed in the small intestine were characterized. Both preproCCKs contain mono basic processing sites for the production of CCK-70 and –8 as seen in turtle and bullfrog. However, compared to these species an unusually large proportion was processed to the small forms CCK-7 and –8 and only minute amounts to larger forms. The encoded preprohormones are very similar to each other and to turtle CCK. Furthermore, they also show a high degree of similarity to the CCKs identified in more distant vertebrates. This confirms that CCK is highly conserved among vertebrates while the structure of gastrin, the other member of the CCK/gastrin family, is considerably more variable.
Keywords: CCK; mRNA; Peptide purification; Regulatory peptide; Hormone; Neuropeptide; Bird; Avian; Gallus gallus; Struthio camelus;

Bufokinin: immunoreactivity, receptor localization and actions in toad intestine and mesenteric circulation by Lu Liu; Fei Shang; Michael A Perry; Alfio Comis; Elizabeth Burcher (1345-1354).
In this study, we have mapped the immunoreactivity and the binding sites for bufokinin, a tachykinin peptide from the toad intestine. Dense bufokinin-immunoreactive fibers were present at the myenteric plexus, but no cell bodies were stained, suggesting an extrinsic origin. Bufokinin nerve fibers were also associated with submucosal blood vessels and mesenteric arteries. Autoradiographic binding sites for [125I]Bolton-Hunter-bufokinin were densely localized over the intestinal circular and longitudinal muscle, submucosal blood vessels and the endothelium of mesenteric arteries. Mesenteric veins had minimal immunoreactivity and binding sites. In the anesthetized toad, topical application of bufokinin onto the mesentery caused a 2.7-fold increase in arterial blood flow, observed using intravital microscopy. This study supports a role for bufokinin as an endogenous spasmogen and hemodynamic regulator in the toad intestine.
Keywords: Bufokinin; Tachykinin receptors; Amphibia; Intestine; Immunohistochemistry; Autoradiography; Mesenteric microcirculation;

Electrospray mass spectrometry was used to identify insulin, glucagon and two peptides related to glucagon-like peptide-1 (GLP-1) in an extract of the pancreas of the Surinam toad, Pipa pipa, a species belonging to the same family as the African clawed frog, Xenopus laevis. Purification and characterization of the peptides established the primary structure of Pipa insulin as A-chain: GIVEQCCHSS10CTLLQLETYC20 N and B-Chain: FSNQR LCGSH10 LVEALHLVCG20 DRGFFYYPKA30. This amino acid sequence contains several substitutions (B5 His → Arg, B16 Tyr → His, A12 Ser → Thr, A14 Tyr→ Leu, A18Asn → Thr) of residues that have otherwise been quite strongly conserved during vertebrate evolution. Pipa glucagon comprises 37 amino acid residues (HSQGTFTSDY10 SKYLDSRRAQ20 DFVQWLMNTK30QSGGLSS) and the 29 amino-acid-residue peptide was not identified in the extract. In Xenopus and mammalian preproglucagons, the glucagon-29 sequence is followed by Lys-Arg which functions as a recognition site for a prohormone convertase. We propose that a point mutation in the gene encoding Pipa preproglucagon has transformed the Lys30-Arg31 processing site into Lys-Gln with the result that the site in no longer recognized by the processing enzyme. In contrast, Pipa GLP-32 and GLP-37 are of the same molecular size as the corresponding peptides from Xenopus.
Keywords: Insulin; Glucagon; GLP; Posttranslational processing;

Insulin and raclopride combine to decrease short-term intake of sucrose solutions by A.J Sipols; G.D Stuber; S.N Klein; M.S Higgins; D.P Figlewicz (1361-1367).
We have previously reported that the hormone insulin can modulate synaptic function of dopamine neurons. To evaluate whether insulin can alter performance of a task which is dependent on intact dopaminergic signaling, we tested rats in a five minute lick rate task, with a range of concentrations of sucrose or oil solutions. Rats received either ip (t –15 min) saline or the D2 receptor antagonist raclopride (50 μg/kg), and intraventricular (t –4 h) saline or insulin (5 mU). Although ineffective on its own, insulin combined with raclopride treatment resulted in significant suppression of sucrose lick rates compared to the saline/saline group. The overall results are consistent with our hypothesis that insulin may modify performance in tasks that are dependent on dopaminergic signaling.
Keywords: Insulin; Dopamine; Rats; Food intake; Reward;

Agouti-related protein (Agrp) is an endogenous melanocortin-4 receptor antagonist implicated in the regulation of food intake. Effects of Agrp on feeding under varying conditions were investigated. Agrp (10 to 100 pmol) was injected into the hypothalamic paraventricular nucleus of satiated (a.m. and p.m. injections) and food-deprived rats, or was co-administered with 117 pmol Neuropeptide Y (NPY). Agrp significantly stimulated light-phase feeding by 24 h post-injection. However, Agrp stimulated dark-phase and deprivation-induced feeding by 4 and 2 h, respectively. Animals receiving NPY and Agrp consumed more than animals receiving either peptide alone, the effect remaining by 24 h.
Keywords: Agouti-related protein (Agrp); Paraventricular nucleus of the hypothalamus (PVN); Site-specific injection; Melanocortin-4 receptor (MC4-R); Melanocortins; Food intake; Rats;

Intragastric β-casomorphin1–7 attenuates the suppression of fat intake by enterostatin☆ by Christy L White; George A Bray; David A York (1377-1381).
The current experiments were designed to compare the feeding response to enterostatin and β-casomorphin1–7 injected intragastrically. Sprague-Dawley rats with a gastric cannula were allowed to chose from high-fat diet (HF) or low-fat diet (LF) in separate jars. Enterostatin injected intragastrically into overnight fasted rats caused a U-shaped dose-dependent reduction in the intake of the HF diet for the first two hours after infusion but had no effect on the LF intake. β-Casomorphin1–7 stimulated the intake of the HF diet but had no effect on the LF diet. Finally, β-casomorphin1–7 blocked the inhibitory effect of enterostatin on HF intake in fasted rats.
Keywords: Enterostatin; β-Casomorphin; Gastric cannula; High fat diet;

Expression of vasoactive intestinal peptide (VIP) receptors in human uterus by Ana M Bajo; Marı́a G Juarranz; Pedro Valenzuela; Pilar Martı́nez; Juan C Prieto; Luis G Guijarro (1383-1388).
We show the existence of functional vasoactive intestinal peptide (VIP) receptors in normal human female genital tract (endometrium, myometrium, ovary and Fallopian tube) as well as in leiomyoma (a frequent uterine pathology). The correlation between VIP binding and stimulation of adenylyl cyclase activity for all studied tissues was linear (r = 0.86) suggesting the expression of VIP receptors throughout the human female genital tract. Immunodetection of VIP receptor subtypes gave different molecular weights for VPAC1 (47 kDa primarily) and VPAC2 (65 kDa), which may be due to different glycosylation extents. In conclusion, this study demonstrates the expression of both subtypes of VIP receptors and their functionality in human female genital tract, suggesting that this neuropeptide could play an important physiological and pathophysiological role at this level.
Keywords: VIP receptors; Adenylyl cyclase; Myometrium; Endometrium; Leiomyoma; Fallopian tube;

Processing of chromogranin A in the parathyroid: generation of parastatin-related peptides by Brigitte H Fasciotto; Joshua C Denny; George H Greeley Jr; David V Cohn (1389-1401).
Chromogranin A (CgA) is a glycoprotein present in secretory granules of endocrine cells. In the parathyroid, it is costored and cosecreted with parathormone (PTH) in response to hypocalcemia. CgA is the precursor of several bioactive peptides including pancreastatin and betagranin. Parastatin (PARA, pCgA347–419) is a novel peptide that we generated in vitro by enzymatic digestion of pCgA. In vitro, it inhibits low Ca2+-stimulated parathyroid secretion. Full activity resides in its first 19 residues. In order to determine if PARA or PARA-derived peptides are natural products of the parathyroid, we generated an antiserum directed against pCgA347–359 corresponding to the bioactive N-terminal sequence of pPARA (pPARA1–13 antiserum), and developed a specific radioimmunoassay that we used in conjunction with various chromatographic separations. We identified small peptides carrying the pPARA1–13 immunoactivity in extracts and secretion medium of porcine parathyroid glands. Continuous and pulse-chase radiolabeling studies, along with immunoprecipitation using PARA1–13 antiserum demonstrate that a newly-synthesized PARA-related peptide fraction with a Mr of 11 kDa is secreted by the parathyroid cells and accumulates in the secretion medium. Edman degradation of the 11 kDa PARA-related peptide band by Edman degradation yielded three major N-terminal sequences: S-K-M-D-R-L-A-K-E-L—(residues 313–322), D-R-L-A-K-E-L-T-A-E—(residues 316–325), and A-K-E-L-T-A-E-K-R-L—(residues 319–329), in a molar ratio of approximately 1:2:1. The peptide bonds required to be cleaved to yield these peptides, Trp-Ser, Met-Asp and Leu-Ala, suggest that a chymotrypsin-like endopeptidase participated in their formation. The molecular size and the results of amino acid compositional analysis, indicate that the C-termini of these peptides extended variably to residues 384–401 of pCgA. These results demonstrate that processing of CgA by the parathyroid gland generates bioactive PARA-related peptides that could affect the gland’s secretory activity.
Keywords: Chromogranin A; Immunoactivity; Parastatin; Processing; Secretion; Parathyroid hormone; Calcium homeostasis;

Age-related changes in the neuropeptide Y effects on murine lymphoproliferation and interleukin-2 production by S. Medina; M. Del Rı́o; A. Hernanz; M. De la Fuente (1403-1409).
Neuropeptide Y (NPY) modulates several aspects of the immune response but it is not known whether NPY responsiveness is altered with aging. In this work, the in vitro effect of NPY at concentrations ranging from 10 14 M to 10 7 M on lymphoproliferation has been studied in spleen, axillary node and thymus leukocytes from young, adult, mature and old BALB/c mice. The spontaneous proliferation of spleen lymphocytes from young mice was significantly stimulated by NPY. In response to the mitogen Con A, lymphoproliferation and IL-2 release by lymphocytes were inhibited significantly by NPY, these effects disappearing with aging. The results show that NPY is a modulator of lymphoproliferation and that this effect disappears progressively with age. Moreover, this regulatory role of NPY may be carried out through a decrease in IL-2 production.
Keywords: Aging; Neuropeptide Y; Lymphoproliferation; IL-2; Mice;

The “two-headed” peptide inhibitors of interleukin-1 action by Alicja Kluczyk; Ignacy Z. Siemiona; Zbigniew Wieczorek (1411-1420).
Two peptide fragments of IL-1 family proteins, ITGSE and VTKFYF compete with IL-1 for the cellular receptor. We synthesized a series of peptides composed of the sequences ITGSE and VTKFYK bound directly to each other or connected by such linkers as (Gly)n, L- and D-Pro residues, Glu and Lys residues (with peptide bond formed by main amino and carboxy groups or by side chain groups), and β-alanine and its homologues. Peptide IX with a γ-Glu linker was the most potent inhibitor of IL-1 action. It was twice as potent as both of the peptides indicated.
Keywords: Interleukin-1; Interleukin-1 receptor antagonist; IL-1 inhibitors; Thymopentin; Peptide immunosuppressors;

Neurotrophin-3 and neurotrophin receptor immunoreactivity in peptidergic enteric neurons by Roberto De Giorgio; Janice Arakawa; Cynthia J. Wetmore; Catia Sternini (1421-1426).
In the rat small intestine, neurotrophin-3 immunoreactivity was identified in ganglion cells and in processes mostly innervating the mucosa and occasionally the muscle layer and vasculature. The vast majority of neurotrophin-3 immunoreactive neurons contained vasoactive intestinal polypeptide (VIP), but not substance P or related tachykinin (SP/TK). Neurotrophin receptors visualized by pan-trk immunoreactivity were found in numerous ganglion cells of both plexuses and in nerve processes in the intestinal wall. Pan-trk submucosal neurons contained VIP (36%) or SP/TK-IR (47%). Pan-trk myenteric neurons contained VIP-IR (57%) or SP/TK (27%). Our data suggest that neurotrophin-3 and neurotrophin receptors may be involved in the maintenance of enteric neuronal circuits, transmission and phenotypic expression.
Keywords: Nerve growth factor; Neurotrophins; Tyrosine kinase receptor; Peptide-containing neurons; Enteric nervous system;

Glucose-dependent insulinotropic peptide signaling pathways in endothelial cells by Q Zhong; R.J Bollag; D.T Dransfield; J Gasalla-Herraiz; K.-H Ding; L Min; C.M Isales (1427-1432).
Glucose-dependent insulinotropic peptide (GIP) potentiates glucose-induced insulin secretion. In addition, GIP has vasoconstrictive or vasodilatory properties depending on the vascular bed affected. In order to assess whether this effect could be related to differences in GIP receptor expression, several different endothelial cell types were examined for GIP receptor expression. GIP receptor splice variants were detected and varied depending on the endothelial cell type. Furthermore, stimulation of these cells with GIP led to cell type dependent differences in activation of the calcium and cAMP signaling pathways. To our knowledge this is the first physiological characterization of receptors for GIP in endothelial cells.
Keywords: Endothelium; Glucose-dependent insulinotropic polypeptide; Peptide hormone receptors; Splice variants;

Fifteen years of prothymosin alpha: contradictory past and new horizons by Alicia Piñeiro; Oscar J Cordero; Montserrat Nogueira (1433-1446).
Prothymosin α (ProTα) is a highly acidic and small protein of only 111 amino acids with an unusual primary structure. One would expected it to play an essential role in the organism, as it has a wide distribution and is high conserved among mammals, yet its exact function remains elusive. Despite the number of effects described for ProTα, intracellular and extracellular, none are accepted as its physiological role. Furthermore, many other aspects of its biology still remain obscure. In this review, we discuss the structural properties, location, gene family, functions and immunomodulatory activities of and cellular receptors for ProTα. These topics are addressed in an attempt to reconcile opposing outlooks while emphasizing those points where scant investigations do exist. We have also re-evaluated some previous results in light of the structural properties of ProTα and have found that molecular mimetism could be the underlying basis. This molecular mimicry hypothesis provides a clue that must not be overlooked for a realistic appraisal of future results.
Keywords: Prothymosin alpha; Structural properties; Physiological role; Molecular mimetism;