All posts in Raw-Peptide Journal (Elsevier)

Publication date: Available online 24 April 2014 Source:Peptides

Author(s): Yi-Ting Tsai , Chung-Yi Lee , Chih-Chin Hsu , Chung-Yi Chang , Ming-Kai Hsueh , Eagle Yi-Kung Huang , Chien-Sung Tsai , Shih-Hurng Loh

The Na⁺-H⁺ exchanger (NHE) and the Na⁺-HCO3 ⁻ co-transporter (NBC) have been confirmed as two major active acid extruders in many mammalian cells. Whether the NHE and NBC functional co-exist in human internal mammary artery smooth muscle cells (HIMASMCs) remains unclear. The aims of the present study were to investigate the acid-extruding mechanisms and to explore the effects of urotensin-II (U-II), a powerful vasoconstrictor, on pHi regulators in HIMASMCs. We investigated the changes of pHi by BCECF-fluorescence in HIMASMCs. We found that (a) two Na⁺-dependent acid extruders, i.e. NHE and NBC, functionally co-exist; (b) U-II (3 ∼ 100nM) induced a concentration-dependent intracellular acidosis; and (c) U-II (3 ∼ 100nM) caused a concentration-dependent increase on NHE activity, while decrease on NBC activity. In summary, we demonstrate for the first time that two acid-extruders, NHE and NBC, functionally co-exist in HIMASMCs. Moreover, U-II induces a concentration-dependent intracellular acidosis through the balanced effect of its effect on increasing NHE activity and decreasing NBC activity

Graphical abstract

Publication date: Available online 18 April 2014 Source:Peptides

Author(s): Yuanjie Mao , Takeshi Tokudome , Ichiro Kishimoto , Kentaro Otani , Mikiya Miyazato , Kenji Kangawa

Both hexarelin and its natural analog ghrelin exert comparable cardioprotective activities. A single dose of ghrelin administered at the very acute phase after experimental myocardial infarction positively affects cardiac function in chronic heart failure. Therefore, this study aimed to determine whether a single dose of oral hexarelin has the same effect in the chronic disease phase. Myocardial infarction or sham operation was generated by left coronary artery ligation in male C57BL/6J mice, which subsequently received one dose of hexarelin or vehicle treatment by oral gavage 30min after operation. Although the mortality within 14 days after myocardial infarction did not differ between the groups, hexarelin treatment protected cardiac function in the chronic phase as evidenced by higher ejection fraction and fractional shortening, as well as lower lung weight/body weight and lung weight/tibial length ratios, compared with vehicle treatment. Hexarelin treatment concurrently lowered plasma epinephrine and dopamine levels, and shifted the balance of autonomic nervous activity toward parasympathetic nervous activity as evidenced by a smaller low/high-frequency power ratio and larger normalized high-frequency power on heart rate variability analysis. The results first demonstrate that one dose of oral hexarelin treatment potentially protects chronic cardiac function after acute myocardial infarction, and implicate that activating growth hormone secretagogue receptor 1a might be beneficial for cardioprotection, although other mechanism may also be involved.

Publication date: Available online 18 April 2014 Source:Peptides

Author(s): Abdurrahman Tufan , Rıdvan Mercan , Ozge Tugce Pasaoglu , Hatice Pasaoglu , Mehmet Akif Ozturk , Berna Goker , Seminur Haznedaroglu

Familial Mediterranean fever (FMF) is characterized by recurrent inflammation of serosal and synovial membranes. Despite the fact that it is a genetic disease, environmental factors, including infections, are shown to be triggering factors associated with the precipitation of attacks in FMF. Antimicrobial peptides (AMPs) are components of innate immunity which exert antimicrobial activity against many microorganisms. Human AMPs; cathelicidin (LL37) and defensins have immunomodulatory properties and are involved in the pathogenesis of many inflammatory disorders. Hence, we investigated serum AMPs in 23 newly diagnosed FMF patients. Blood samples were obtained at baseline, 6 months after initiation of colchicine and during an attack. Twenty-four healthy individuals constituted the control group. The concentrations of LL37, alpha-1, beta-1 and beta-2 defensins were determined by ELISA. Serum AMPs did not change during attacks and did not correlate with acute phase reactants. However, serum LL37 and defensins were found to be remarkably higher in FMF patients compared to healthy individuals both at baseline and 6 months after initiation of colchicine therapy which suggest that AMPs might have a role in the pathogenesis of FMF.

Publication date: Available online 2 April 2014 Source:Peptides

Author(s): Meet Zandawala , Constantine Poulos , Ian Orchard

The calcitonin-like diuretic hormone (CT/DH) in Rhodnius prolixus influences various tissues associated with feeding-related physiological events. The receptors for this peptide have also been identified and shown to be expressed in these tissues. In the present study, we have investigated the effects of two R. prolixus CT/DH analogs (full-length form and N-terminal truncated form) on hindgut contractions and in a heterologous receptor expression system. The analogs contained the amino acid methyl-homoserine in place of methionine in order to prevent them from being oxidized and thus increase their stability. The full-length form of the analog retained all of its activity in our assays when compared to the endogenous peptide. Truncated analog displayed no activity in our assays.

Publication date: Available online 2 April 2014 Source:Peptides

Author(s): Santi M. Mandal , Rashmi Bharti , William F. Porto , Samiran S. Gauri , Mahitosh Mandal , Octavio L. Franco , Ananta K. Ghosh

Pharmaceutical industries have renewed interest in screening multifunctional bioactive peptides as a marketable product in health care applications. In this context, several animal and plant peptides with potential bioactivity have been reported. Milk proteins and peptides have received much attention as a source of health-enhancing components to be incorporated into nutraceuticals and functional foods. By using this source, 24 peptides have been fractionated and purified from human milk using RP-HPLC. Multifunctional roles including antimicrobial, antioxidant and growth stimulating activity have been evaluated in all 24 fractions. Nevertheless, only 4 fractions show multiple combined activities among them. Using a proteomic approach, two of these four peptides have been identified as lactoferrin derived peptide and kappa casein short chain peptide. Lactoferrin derived peptide (f8) is arginine-rich and kappa casein derived (f12) peptide is proline-rich. Both peptides (f8 and f12) showed antimicrobial activity against both Gram-positive and Gram-negative bacteria. Fraction 8 (f8) exhibits growth stimulating activity in 3T3 cell line and f12 shows higher free radical scavenging activity in comparison to other fractions. Finally, both peptides were in silico evaluated and some insights into their mechanism of action were provided. Thus, results indicate that these identified peptides have multiple biological activities which are valuable for the quick development of the neonate and may be considered as potential biotechnological products for for nutraceutical industry.

Graphical abstract

Publication date: Available online 2 April 2014 Source:Peptides

Author(s): Gonul Catli , Ahmet Anik , Hale Ünver Tuhan , Tuncay Küme , Ece Bober , Ayhan Abaci

The Relation of Leptin and Soluble Leptin Receptor Levels with Metabolic and Clinical Parameters in Obese and Healthy Children Objective We investigated the relation of serum leptin, soluble leptin receptor (sLR) and free leptin index (FLI) with metabolic and anthropometric parameters in obese and healthy children. Methods Height, weight, waist circumference (WC), fasting serum glucose, insulin, lipid profile, leptin and sLR levels of 35 obese children and 36 healthy children were measured and FLI was calculated as the ratio of leptin to sLR. Results In obese children, serum leptin and FLI were found significantly higher, while sLR level was significantly lower than the healthy children. Comparison of obese children regarding the insulin resistance showed significantly higher serum leptin and FLI in the insulin resistant group; however sLR level was not different between the insulin resistant and non-resistant obese children. In obese children, sLR was not correlated with any of the metabolic parameters except total cholesterol, while FLI was significantly and positively correlated with BMI, WC, TC, fasting insulin, and HOMA-IR. However, regression analysis confirmed that the HOMA-IR was the only independent variable significantly correlated with FLI in obese children. Conclusions Findings of this study suggest that in obese children and adolescents i) serum leptin and FLI were found significantly higher, while sLR level was significantly lower than the healthy children, ii) increased FLI might be a compensatory mechanism for increasing leptin effect in peripheral tissue, iii) FLI is a more accurate marker to evaluate leptin resistance than leptin or sLR alone and, iv) increased FLI may contribute toward the development of hyperinsulinemia and insulin resistance.

Publication date: Available online 1 April 2014 Source:Peptides

Author(s): Shan Gao , Byung Mun Park , Seung Ah Cha , Sung Zoo Kim , Suhn Hee Kim

Peroxisome proliferator-activated receptor-gamma (PPAR- γ), a nuclear transcription factor, is a key regulator of insulin signalling, and glucose and fat metabolism. In this study, we evaluated the direct effect of PPAR- γ ligand on the secretion of atrial natriuretic peptide (ANP). The isolated perfused beating atria were used and rosiglitazone (0.01, 0.3 and 1μM) or telmisartan was perfused into atria with and without inhibitors. High frequency stimulation caused a decreased atrial contractility by 40% and an increased ANP secretion by 80%. Rosiglitazone augmented high frequency-induced ANP secretion and concentration in a dose-dependent manner. Rosiglitazone-induced ANP secretion was attenuated by the pretreatment with PPAR-γ antagonist (GW 9662), or inhibitor for phosphoinositol 3-kinase (PI3-kinase, wortmannin), Akt (API-2) or nitric oxide synthase (L-NAME). Telmisartan, a partial agonist of PPAR-γ with angiotensin II type 1 receptor (AT1R) blocker, also stimulated ANP secretion, which was more potent than rosiglitazone or losartan. Infusion of rosiglitazone or telmisartan in anesthetized rats tended to decrease mean arterial pressure and to increase pulse pressure without difference. A plasma ANP level was increased by telmisartan more than by rosiglitazone. In diabetic rats, an increased plasma ANP level was more prominent than sham rats. Therefore, we suggest that rosiglitazone stimulates high frequency-induced ANP secretion through the PPAR-γ receptor-PI3-kinase-Akt-eNOS pathway and telmisartan shows synergistic effect on ANP secretion.

Publication date: Available online 26 March 2014 Source:Peptides

Author(s): Nelson Marmiroli

This review focuses on plant peptides involved in defense against pathogen infection and those involved in the regulation of growth and development. Defense peptides, defensins, cyclotides and anti-microbial peptides are compared and contrasted. Signaling peptides are classified according to their major sites of activity. Finally, a network approach to creating an interactomic peptide map is described.

Publication date: Available online 15 March 2014 Source:Peptides

Author(s): Kairong Wang , Jiexi Yan , Wen Dang , Junqiu Xie , Bo Yan , Wenjin Yan , Mengyang Sun , Bangzhi Zhang , Mingxia Ma , Yanyan Zhao , Fengjing Jia , Ranran Zhu , Wei Chen , Rui Wang

With the increasing emergence of resistant fungi, the discovery and development of novel antifungal therapeutics were urgently needed. Compared with conventional antibiotics, the limited propensity of AMPs to induce resistance in pathogens has attracted great interest. In the present study, the antifungal activity and its mechanism-of-action of polybia-MPI, a cationic peptide from the venom of Social wasp Polybia Paulista were investigated. We demonstrated that polybia-MPI could potently inhibit the growth of Candida albicans (C. albicans) and Candida glabrata (C. glabrata). The 50% inhibitory concentrations (IC50) of Poybia-MPI against cancer cells were much higher than the MICs againt the tested C. albican and C. glabrata cells, indicating that polybia-MPI had high selectivity between the fungal and mammalian cells. Our results also indicated that membrane disturbance mechanism was involved in the antifungal activity. Furthermore, polybia-MPI could inhibit the biofilm forming of C. glabrata, which was frequently associated with clinically-significant biofilm. These results suggest that polybia-MPI has great advantages in the development of antifungal agents.

16 February 2014 Source:Peptides

Plant immune responses involve a wide diversity of physiological reactions that are induced by the recognition of pathogens, such as hypersensitive responses, cell wall modifications, and the synthesis of antimicrobial molecules including antimicrobial peptides (AMPs). Read more...