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Sample records for a-i mimetic peptide

  1. Formation of stable nanodiscs by bihelical apolipoprotein A-I mimetic peptide.

    PubMed

    Kariyazono, Hirokazu; Nadai, Ryo; Miyajima, Rin; Takechi-Haraya, Yuki; Baba, Teruhiko; Shigenaga, Akira; Okuhira, Keiichiro; Otaka, Akira; Saito, Hiroyuki

    2016-02-01

    Nanodiscs are composed of scaffold protein or peptide such as apolipoprotein A-I (apoA-I) and phospholipids. Although peptide-based nanodiscs have an advantage to modulate the size of nanodiscs by changing phospholipid/peptide ratios, they are usually less stable than apoA-I-based nanodiscs. In this study, we designed a novel nanodisc scaffold peptide (NSP) that has proline-punctuated bihelical amphipathic structure based on apoA-I mimetic peptides. NSP formed α-helical structure on 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) nanodiscs prepared by cholate dialysis method. Dynamic light scattering measurements demonstrated that diameters of NSP nanodiscs vary depending upon POPC/NSP ratios. Comparison of thermal unfolding of nanodiscs monitored by circular dichroism measurements demonstrated that NSP forms much more stable nanodiscs with POPC than monohelical peptide, 4F, exhibiting comparable stability to apoA-I-POPC nanodiscs. Intrinsic Trp fluorescence measurements showed that Trp residues of NSP exhibit more hydrophobic environment than that of 4 F on nanodiscs, suggesting the stronger interaction of NSP with phospholipids. Thus, the bihelical structure of NSP appears to increase the stability of nanodiscs because of the enhanced interaction of peptides with phospholipids. In addition, NSP as well as 4F spontaneously solubilized POPC vesicles into nanodiscs without using detergent. These results indicate that bihelical NSP forms nanodiscs with comparable stability to apoA-I and has an ability to control the size of nanodiscs simply by changing phospholipid/peptide ratios. PMID:26780967

  2. The A's Have It: Developing Apolipoprotein A-I Mimetic Peptides Into a Novel Treatment for Asthma.

    PubMed

    Yao, Xianglan; Gordon, Elizabeth M; Barochia, Amisha V; Remaley, Alan T; Levine, Stewart J

    2016-08-01

    New treatments are needed for patients with asthma who are refractory to standard therapies, such as individuals with a phenotype of "type 2-low" inflammation. This important clinical problem could potentially be addressed by the development of apolipoprotein A-I (apoA-I) mimetic peptides. ApoA-I interacts with its cellular receptor, the ATP-binding cassette subfamily A, member 1 (ABCA1), to facilitate cholesterol efflux out of cells to form nascent high-density lipoprotein particles. The ability of the apoA-I/ABCA1 pathway to promote cholesterol efflux from cells that mediate adaptive immunity, such as antigen-presenting cells, can attenuate their function. Data from experimental murine models have shown that the apoA-I/ABCA1 pathway can reduce neutrophilic airway inflammation, primarily by suppressing the production of granulocyte-colony stimulating factor. Furthermore, administration of apoA-I mimetic peptides to experimental murine models of allergic asthma has decreased both neutrophilic and eosinophilic airway inflammation, as well as airway hyperresponsiveness and mucous cell metaplasia. Higher serum levels of apoA-I have also been associated with less severe airflow obstruction in patients with asthma. Collectively, these results suggest that the apoA-I/ABCA1 pathway may have a protective effect in asthma, and support the concept of advancing inhaled apoA-I mimetic peptides to clinical trials that can assess their safety and effectiveness. Thus, we propose that the development of inhaled apoA-I mimetic peptides as a new treatment could represent a clinical advance for patients with severe asthma who are unresponsive to other therapies. PMID:27327118

  3. Bioenergetic programming of macrophages by the apolipoprotein A-I mimetic peptide 4F.

    PubMed

    Datta, Geeta; Kramer, Philip A; Johnson, Michelle S; Sawada, Hirotaka; Smythies, Lesley E; Crossman, David K; Chacko, Balu; Ballinger, Scott W; Westbrook, David G; Mayakonda, Palgunachari; Anantharamaiah, G M; Darley-Usmar, Victor M; White, C Roger

    2015-05-01

    The apoA-I (apolipoprotein A-I) mimetic peptide 4F favours the differentiation of human monocytes to an alternatively activated M2 phenotype. The goal of the present study was to test whether the 4F-mediated differentiation of MDMs (monocyte-derived macrophages) requires the induction of an oxidative metabolic programme. 4F treatment induced several genes in MDMs that play an important role in lipid metabolism, including PPARγ (peroxisome-proliferator-activated receptor γ) and CD36. Addition of 4F was associated with a significant increase in FA (fatty acid) uptake and oxidation compared with vehicle treatment. Mitochondrial respiration was assessed by measurement of the OCR (oxygen-consumption rate). 4F increased basal and ATP-linked OCR as well as maximal uncoupled mitochondrial respiration. These changes were associated with a significant increase in ΔΨm (mitochondrial membrane potential). The increase in metabolic activity in 4F-treated MDMs was attenuated by etomoxir, an inhibitor of mitochondrial FA uptake. Finally, addition of the PPARγ antagonist T0070907 to 4F-treated MDMs reduced the expression of CD163 and CD36, cell-surface markers for M2 macrophages, and reduced basal and ATP-linked OCR. These results support our hypothesis that the 4F-mediated differentiation of MDMs to an anti-inflammatory phenotype is due, in part, to an increase in FA uptake and mitochondrial oxidative metabolism. PMID:25742174

  4. Apolipoprotein A-I mimetic peptide 4F blocks sphingomyelinase-induced LDL aggregation[S

    PubMed Central

    Nguyen, Su Duy; Javanainen, Matti; Rissanen, Sami; Zhao, Hongxia; Huusko, Jenni; Kivelä, Annukka M.; Ylä-Herttuala, Seppo; Navab, Mohamad; Fogelman, Alan M.; Vattulainen, Ilpo; Kovanen, Petri T.; Öörni, Katariina

    2015-01-01

    Lipolytic modification of LDL particles by SMase generates LDL aggregates with a strong affinity for human arterial proteoglycans and may so enhance LDL retention in the arterial wall. Here, we evaluated the effects of apoA-I mimetic peptide 4F on structural and functional properties of the SMase-modified LDL particles. LDL particles with and without 4F were incubated with SMase, after which their aggregation, structure, and proteoglycan binding were analyzed. At a molar ratio of L-4F to apoB-100 of 2.5 to 20:1, 4F dose-dependently inhibited SMase-induced LDL aggregation. At a molar ratio of 20:1, SMase-induced aggregation was fully blocked. Binding of 4F to LDL particles inhibited SMase-induced hydrolysis of LDL by 10% and prevented SMase-induced LDL aggregation. In addition, the binding of the SMase-modified LDL particles to human aortic proteoglycans was dose-dependently inhibited by pretreating LDL with 4F. The 4F stabilized apoB-100 conformation and inhibited SMase-induced conformational changes of apoB-100. Molecular dynamic simulations showed that upon binding to protein-free LDL surface, 4F locally alters membrane order and fluidity and induces structural changes to the lipid layer. Collectively, 4F stabilizes LDL particles by preventing the SMase-induced conformational changes in apoB-100 and so blocks SMase-induced LDL aggregation and the resulting increase in LDL retention. PMID:25861792

  5. ApoA-I mimetics.

    PubMed

    Stoekenbroek, R M; Stroes, E S; Hovingh, G K

    2015-01-01

    A wealth of evidence indicates that plasma levels of high-density lipoprotein cholesterol (HDL-C) are inversely related to the risk of cardiovascular disease (CVD). Consequently, HDL-C has been considered a target for therapy in order to reduce the residual CVD burden that remains significant, even after application of current state-of-the-art medical interventions. In recent years, however, a number of clinical trials of therapeutic strategies that increase HDL-C levels failed to show the anticipated beneficial effect on CVD outcomes. As a result, attention has begun to shift toward strategies to improve HDL functionality, rather than levels of HDL-C per se. ApoA-I, the major protein component of HDL, is considered to play an important role in many of the antiatherogenic functions of HDL, most notably reverse cholesterol transport (RCT), and several therapies have been developed to mimic apoA-I function, including administration of apoA-I, mutated variants of apoA-I, and apoA-I mimetic peptides. Based on the potential anti-inflammatory effects, apoA-I mimetics hold promise not only as anti-atherosclerotic therapy but also in other therapeutic areas. PMID:25523005

  6. In vivo efficacy of HDL-like nanolipid particles containing multivalent peptide mimetics of apolipoprotein A-I.

    PubMed

    Zhao, Yannan; Black, Audrey S; Bonnet, David J; Maryanoff, Bruce E; Curtiss, Linda K; Leman, Luke J; Ghadiri, M Reza

    2014-10-01

    We have observed that molecular constructs based on multiple apoA-I mimetic peptides attached to a branched scaffold display promising anti-atherosclerosis functions in vitro. Building on these promising results, we now describe chronic in vivo studies to assess anti-atherosclerotic efficacy of HDL-like nanoparticles assembled from a trimeric construct, administered over 10 weeks either ip or orally to LDL receptor-null mice. When dosed ip, the trimer-based nanolipids markedly reduced plasma LDL-cholesterol levels by 40%, unlike many other apoA-I mimetic peptides, and were substantially atheroprotective. Surprisingly, these nanoparticles were also effective when administered orally at a dose of 75 mg/kg, despite the peptide construct being composed of l-amino acids and being undetectable in the plasma. The orally administered nanoparticles reduced whole aorta lesion areas by 55% and aortic sinus lesion volumes by 71%. Reductions in plasma cholesterol were due to the loss of non-HDL lipoproteins, while plasma HDL-cholesterol levels were increased. At a 10-fold lower oral dose, the nanoparticles were marginally effective in reducing atherosclerotic lesions. Intriguingly, analogous results were obtained with nanolipids of the corresponding monomeric peptide. These nanolipid formulations provide an avenue for developing orally efficacious therapeutic agents to manage atherosclerosis. PMID:24975585

  7. An apoA-I mimetic peptide containing a proline residue has greater in vivo HDL binding and anti-inflammatory ability than the 4F peptide.

    PubMed

    Wool, Geoffrey D; Vaisar, Tomas; Reardon, Catherine A; Getz, Godfrey S

    2009-09-01

    Modifying apolipoprotein (apo) A-I mimetic peptides to include a proline-punctuated alpha-helical repeat increases their anti-inflammatory properties as well as allows better mimicry of full-length apoA-I function. This study compares the following mimetics, either acetylated or biotinylated (b): 4F (18mer) and 4F-proline-4F (37mer, Pro). b4F interacts with both mouse HDL (moHDL) and LDL in vitro. b4F in vivo plasma clearance kinetics are not affected by mouse HDL level. Administration of biotinylated peptides to mice demonstrates that b4F does not associate with lipoproteins smaller than LDL in vivo, though it does associate with fractions containing free hemoglobin (Hb). In contrast, bPro specifically interacts with HDL. b4F and bPro show opposite binding responses to HDL by surface plasmon resonance. Administration of acetylated Pro to apoE(-/-) mice significantly decreases plasma serum amyloid A levels, while acetylated 4F does not have this ability. In contrast to previous reports that inferred that 4F associates with HDL in vivo, we systematically examined this potential interaction and demonstrated that b4F does not interact with HDL in vivo but rather elutes with Hb-containing plasma fractions. bPro, however, specifically binds to moHDL in vivo. In addition, the number of amphipathic alpha-helices and their linker influences the anti-inflammatory effects of apoA-I mimetic peptides in vivo. PMID:19433476

  8. An apoA-I mimetic peptide containing a proline residue has greater in vivo HDL binding and anti-inflammatory ability than the 4F peptide

    PubMed Central

    Wool, Geoffrey D.; Vaisar, Tomas; Reardon, Catherine A.; Getz, Godfrey S.

    2009-01-01

    Modifying apolipoprotein (apo) A-I mimetic peptides to include a proline-punctuated α-helical repeat increases their anti-inflammatory properties as well as allows better mimicry of full-length apoA-I function. This study compares the following mimetics, either acetylated or biotinylated (b): 4F (18mer) and 4F-proline-4F (37mer, Pro). b4F interacts with both mouse HDL (moHDL) and LDL in vitro. b4F in vivo plasma clearance kinetics are not affected by mouse HDL level. Administration of biotinylated peptides to mice demonstrates that b4F does not associate with lipoproteins smaller than LDL in vivo, though it does associate with fractions containing free hemoglobin (Hb). In contrast, bPro specifically interacts with HDL. b4F and bPro show opposite binding responses to HDL by surface plasmon resonance. Administration of acetylated Pro to apoE−/− mice significantly decreases plasma serum amyloid A levels, while acetylated 4F does not have this ability. In contrast to previous reports that inferred that 4F associates with HDL in vivo, we systematically examined this potential interaction and demonstrated that b4F does not interact with HDL in vivo but rather elutes with Hb-containing plasma fractions. bPro, however, specifically binds to moHDL in vivo. In addition, the number of amphipathic α-helices and their linker influences the anti-inflammatory effects of apoA-I mimetic peptides in vivo. PMID:19433476

  9. Anti-inflammatory mechanisms of apolipoprotein A-I mimetic peptide in acute respiratory distress syndrome secondary to sepsis.

    PubMed

    Sharifov, Oleg F; Xu, Xin; Gaggar, Amit; Grizzle, William E; Mishra, Vinod K; Honavar, Jaideep; Litovsky, Silvio H; Palgunachari, Mayakonda N; White, C Roger; Anantharamaiah, G M; Gupta, Himanshu

    2013-01-01

    Acute respiratory distress syndrome (ARDS) due to sepsis has a high mortality rate with limited treatment options. High density lipoprotein (HDL) exerts innate protective effects in systemic inflammation. However, its role in ARDS has not been well studied. Peptides such as L-4F mimic the secondary structural features and functions of apolipoprotein (apo)A-I, the major protein component of HDL. We set out to measure changes in HDL in sepsis-mediated ARDS patients, and to study the potential of L-4F to prevent sepsis-mediated ARDS in a rodent model of lipopolysaccharide (LPS)-mediated acute lung injury, and a combination of primary human leukocytes and human ARDS serum. We also analyzed serum from non-lung disease intubated patients (controls) and sepsis-mediated ARDS patients. Compared to controls, ARDS demonstrates increased serum endotoxin and IL-6 levels, and decreased HDL, apoA-I and activity of anti-oxidant HDL-associated paraoxanase-1. L-4F inhibits the activation of isolated human leukocytes and neutrophils by ARDS serum and LPS in vitro. Further, L-4F decreased endotoxin activity and preserved anti-oxidant properties of HDL both in vitro and in vivo. In a rat model of severe endotoxemia, L-4F significantly decreased mortality and reduces lung and liver injury, even when administered 1 hour post LPS. Our study suggests the protective role of the apoA-I mimetic peptide L-4F in ARDS and gram-negative endotoxemia and warrant further clinical evaluation. The main protective mechanisms of L-4F are due to direct inhibition of endotoxin activity and preservation of HDL anti-oxidant activity. PMID:23691230

  10. Apolipoprotein A-I mimetic peptide D-4F promotes human endothelial progenitor cell proliferation, migration, adhesion though eNOS/NO pathway.

    PubMed

    Zhang, Zhengang; Qun, Jianhua; Cao, Chunmei; Wang, Jun; Li, Wei; Wu, Yong; Du, Lin; Zhao, Pei; Gong, Kaizheng

    2012-04-01

    Circulating endothelial progenitor cells (EPCs) have a critical role in endothelial maintenance and repair. Apolipoprotein A-I mimetic peptide D-4F has been shown to posses anti-atherogenic properties via sequestration of oxidized phospholipids, induction of remodeling of high density lipoprotein and promotion of cholesterol efflux from macrophage-derived foam cells. In this study, we test the effects of D-4F on EPC biology. EPCs were isolated from the peripheral venous blood of healthy male volunteers and characterized by 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine-labeled acetylated LDL uptake and ulex europaeus agglutinin binding and flow cytometry. Cell proliferation, migration, adhesion, nitric oxide production and endothelial nitric oxide synthase (eNOS) expression in the absence and presence of D-4F or simvastatin (as a positive control), were assayed. We demonstrated that D-4F significantly enhanced EPC proliferation, migration and adhesion in a dose-dependent manner compared with vehicle. However, all of the favorable effects of D-4F on EPCs were dramatically attenuated by preincubation with NOS inhibitor L-NAME. Further, D-4F also increased nitric oxide production in culture supernatant and the levels of eNOS expression and phosphorylation. The stimulatory effects of D-4F (10 μg/ml) on EPC biology were comparable to 0.5 μM simvastatin. These results suggest that eNOS/NO pathway mediates the functional modulation of EPC biology in response to D-4F treatment and support the notion that the beneficial role of D-4F on EPCs may be one of the important components of its anti-atherogenic potential. PMID:21947883

  11. Antiatherogenic effects of newly developed apolipoprotein A-I mimetic peptide/phospholipid complexes against aortic plaque burden in Watanabe-heritable hyperlipidemic rabbits.

    PubMed

    Iwata, Atsushi; Miura, Shin-ichiro; Zhang, Bo; Imaizumi, Satoshi; Uehara, Yoshinari; Shiomi, Masashi; Saku, Keijiro

    2011-10-01

    This study analyzed the antiatherogenic effects of newly developed apolipoprotein A-I (ApoA-I) mimetic peptide/phospholipid complexes (ETC-642) against the aortic plaque burden in vivo. We used human macrophage cells to analyze cholesterol efflux by ETC-642. Watanabe-heritable hyperlipidemic (WHHL) rabbits were divided into 3 groups: low- (15mg/kg) and high-dose ETC-642 (50mg/kg), and placebo. The test material was injected twice/week for 12 weeks. The aortic plaque burden was assessed by intravascular ultrasound (IVUS) at 0 and 12 weeks. Plasma lipid profiles were analyzed by capillary isotachophoresis every 4 weeks. ETC-642 had an effect on cholesterol efflux comparable to that of conventional rHDL. In WHHL rabbits, high-dose ETC-642 inhibited the progression of aortic atherosclerosis compared to placebo. There was no change in the percentage of plaque volume (%PV) in the high-dose group between before (30.9%) and after infusion (28.6%), whereas there was a significant increase in the control group from 27.8% to 37.9%. ETC-642 significantly reduced charge-modified low-density lipoprotein (LDL) by converting more negative-charged modified LDL to less negative-charged LDL, and reduced small dense (sd) LDL by converting it into large, buoyant (lb) LDL. Changes in the %PV were positively correlated with changes in negative-charged modified LDL (r=0.61, p<0.01) and sdLDL (r=0.59, p<0.01), and negatively correlated with changes in less negative-charged LDL (r=-0.43, p<0.01) and lbLDL (r=-0.57, p<0.01). In conclusion, the ETC-642-induced remodeling of sdLDL to large and lbLDL and the enhancement of cholesterol efflux may prevent progression of the aortic plaque burden. HDL-based therapy may be useful for preventing the progression of plaque volume. PMID:21696737

  12. Apolipoprotein A-I Mimetic Peptide D-4F Reduces Cardiac Hypertrophy and Improves Apolipoprotein A-I-Mediated Reverse Cholesterol Transport From Cardiac Tissue in LDL Receptor-null Mice Fed a Western Diet.

    PubMed

    Han, Jie; Zhang, Song; Ye, Ping; Liu, Yong-Xue; Qin, Yan-Wen; Miao, Dong-Mei

    2016-05-01

    Epidemiological studies have suggested that hypercholesterolemia is an independent determinant of increased left ventricular (LV) mass. Because high-density lipoprotein and its major protein apolipoprotein A-I (apoA-I) mediate reverse cholesterol transport (RCT) and have cardiac protective effects, we hypothesized that the apoA-I mimetic peptide D-4F could promote RCT in cardiac tissue and decrease cardiac hypertrophy induced by hypercholesterolemia. Low-density lipoprotein receptor-null mice were fed by a Western diet for 18 weeks and then randomized to receive water, or D-4F 0.3 mg/mL, or D-4F 0.5 mg/mL added to drinking water for 6 weeks. After D-4F administration, an increase in high-density lipoprotein cholesterol and a decrease in low-density lipoprotein cholesterol, total cholesterol, and triglyceride in a trend toward dose-responsivity were found in cardiac tissue. Ultrasound biomicroscopy revealed a reduction in LV posterior wall end-diastolic dimension, and an increase in mitral valve E/A ratio and LV ejection fraction. Hematoxylin-eosin staining showed reduced LV wall thickness and myocardial cell diameter. The protein levels of ABCA1 and LXRα were elevated in cardiac tissue of D-4F treated mice compared with the controls (P < 0.05). These results demonstrated that D-4F treatment reduced cardiac hypertrophy, and improved cardiac performance in low-density lipoprotein receptor-null mice fed a Western diet, presumably through the LXRα-ABCA1 pathway associated with enhanced myocardial RCT. PMID:26828321

  13. Collagen Mimetic Peptides: Progress Towards Functional Applications

    PubMed Central

    Yu, S. Michael; Li, Yang; Kim, Daniel

    2015-01-01

    Traditionally, collagen mimetic peptides (CMPs) have been used for elucidating the structure of the collagen triple helix and the factors responsible for its stabilization. The wealth of fundamental knowledge on collagen structure and cell-extracellular matrix (ECM) interactions accumulated over the past decades has led to a recent burst of research exploring the potential of CMPs to recreate the higher order assembly and biological function of natural collagens for biomedical applications. Although a large portion of such research is still at an early stage, the collagen triple helix has become a promising structural motif for engineering self-assembled, hierarchical constructs similar to natural tissue scaffolds which are expected to exhibit unique or enhanced biological activities. This paper reviews recent progress in the field of collagen mimetic peptides that bears both direct and indirect implications to engineering collagen-like materials for potential biomedical use. Various CMPs and collagen-like proteins that mimic either structural or functional characteristics of natural collagens are discussed with particular emphasis on providing helpful information to bioengineers and biomaterials scientists interested in collagen engineering. PMID:26316880

  14. A glycosaminoglycan mimetic peptide nanofiber gel as an osteoinductive scaffold.

    PubMed

    Tansik, Gulistan; Kilic, Erden; Beter, Mustafa; Demiralp, Bahtiyar; Kiziltas Sendur, Gullu; Can, Nuray; Ozkan, Huseyin; Ergul, Elif; Guler, Mustafa O; Tekinay, Ayse B

    2016-08-16

    Biomineralization of the extracellular matrix (ECM) plays a crucial role in bone formation. Functional and structural biomimetic native bone ECM components can therefore be used to change the fate of stem cells and induce bone regeneration and mineralization. Glycosaminoglycan (GAG) mimetic peptide nanofibers can interact with several growth factors. These nanostructures are capable of enhancing the osteogenic activity and mineral deposition of osteoblastic cells, which is indicative of their potential application in bone tissue regeneration. In this study, we investigated the potential of GAG-mimetic peptide nanofibers to promote the osteogenic differentiation of rat mesenchymal stem cells (rMSCs) in vitro and enhance the bone regeneration and biomineralization process in vivo in a rabbit tibial bone defect model. Alkaline phosphatase (ALP) activity and Alizarin red staining results suggested that osteogenic differentiation is enhanced when rMSCs are cultured on GAG-mimetic peptide nanofibers. Moreover, osteogenic marker genes were shown to be upregulated in the presence of the peptide nanofiber system. Histological and micro-computed tomography (Micro-CT) observations of regenerated bone defects in rabbit tibia bone also suggested that the injection of a GAG-mimetic nanofiber gel supports cortical bone deposition by enhancing the secretion of an inorganic mineral matrix. The volume of the repaired cortical bone was higher in GAG-PA gel injected animals. The overall results indicate that GAG-mimetic peptide nanofibers can be utilized effectively as a new bioactive platform for bone regeneration. PMID:27447002

  15. Multi-Facial, Non-Peptidic α-Helix Mimetics

    PubMed Central

    Lanning, Maryanna E.; Fletcher, Steven

    2015-01-01

    α-Helices often recognize their target proteins at protein–protein interfaces through more than one recognition face. This review describes the state-of-the-art in the design of non-peptidic α-helix mimetics that reproduce functionality from multiple faces of an α-helix. PMID:26404384

  16. Small peptides as potent mimetics of the protein hormone erythropoietin.

    PubMed

    Wrighton, N C; Farrell, F X; Chang, R; Kashyap, A K; Barbone, F P; Mulcahy, L S; Johnson, D L; Barrett, R W; Jolliffe, L K; Dower, W J

    1996-07-26

    Random phage display peptide libraries and affinity selective methods were used to isolate small peptides that bind to and activate the receptor for the cytokine erythropoietin (EPO). In a panel of in vitro biological assays, the peptides act as full agonists and they can also stimulate erythropoiesis in mice. These agonists are represented by a 14- amino acid disulfide-bonded, cyclic peptide with the minimum consensus sequence YXCXXGPXTWXCXP, where X represents positions allowing occupation by several amino acids. The amino acid sequences of these peptides are not found in the primary sequence of EPO. The signaling pathways activated by these peptides appear to be identical to those induced by the natural ligand. This discovery may form the basis for the design of small molecule mimetics of EPO. PMID:8662529

  17. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    NASA Astrophysics Data System (ADS)

    Rexeisen, Emilie Lynn

    Many therapeutic strategies incorporate peptides into their designs to mimic the natural protein ligands found in vivo. A few examples are the short peptide sequences RGD and PHSRN that mimic the primary and synergy-binding domains of the extracellular matrix protein, fibronectin, which is recognized by the cell surface receptor, alpha5beta 1 integrin. Even though scaffold modification with biomimetic peptides remains one of the most promising approaches for tissue engineering, the use of these peptides in therapeutic tissue-engineered products and drug delivery systems available on the commercial market is limited because the peptides are not easily able to mimic the natural protein. The design of a peptide that can effectively target the alpha5beta1 integrin would greatly increase biomimetic scaffold therapeutic potential. A novel peptide containing both the RGD primary binding domain and PHSRN synergy-binding domain for fibronectin joined with the appropriate linker should bind alpha 5beta1 integrin more efficiently and lead to greater cell adhesion over RGD alone. Several fibronectin mimetic peptides were designed and coupled to dialkyl hydrocarbon tails to make peptide-amphiphiles. The peptides contained different linkers connecting the two binding domains and different spacers separating the hydrophobic tails from the hydrophilic headgroups. The peptide-amphiphiles were deposited on mica substrates using the Langmuir-Blodgett technique. Langmuir isotherms indicated that the peptide-amphiphiles that contained higher numbers of serine residues formed a more tightly packed monolayer, but the increased number of serines also made transferring the amphiphiles to the mica substrate more difficult. Atomic force microscopy (AFM) images of the bilayers showed that the headgroups might be bent, forming small divots in the surface. These divots may help expose the PHSRN synergy-binding domain. Parallel studies undertaken by fellow group members showed that human

  18. Basal Lamina Mimetic Nanofibrous Peptide Networks for Skeletal Myogenesis

    NASA Astrophysics Data System (ADS)

    Yasa, I. Ceren; Gunduz, Nuray; Kilinc, Murat; Guler, Mustafa O.; Tekinay, Ayse B.

    2015-11-01

    Extracellular matrix (ECM) is crucial for the coordination and regulation of cell adhesion, recruitment, differentiation and death. Therefore, equilibrium between cell-cell and cell-matrix interactions and matrix-associated signals are important for the normal functioning of cells, as well as for regeneration. In this work, we describe importance of adhesive signals for myoblast cells’ growth and differentiation by generating a novel ECM mimetic peptide nanofiber scaffold system. We show that not only structure but also composition of bioactive signals are important for cell adhesion, growth and differentiation by mimicking the compositional and structural properties of native skeletal muscle basal lamina. We conjugated laminin-derived integrin binding peptide sequence, “IKVAV”, and fibronectin-derived well known adhesive sequence, “RGD”, into peptide nanostructures to provide adhesive and myogenic cues on a nanofibrous morphology. The myogenic and adhesive signals exhibited a synergistic effect on model myoblasts, C2C12 cells. Our results showed that self-assembled peptide nanofibers presenting laminin derived epitopes support adhesion, growth and proliferation of the cells and significantly promote the expression of skeletal muscle-specific marker genes. The functional peptide nanofibers used in this study present a biocompatible and biodegradable microenvironment, which is capable of supporting the growth and differentiation of C2C12 myoblasts into myotubes.

  19. Basal Lamina Mimetic Nanofibrous Peptide Networks for Skeletal Myogenesis

    PubMed Central

    Yasa, I. Ceren; Gunduz, Nuray; Kilinc, Murat; Guler, Mustafa O.; Tekinay, Ayse B.

    2015-01-01

    Extracellular matrix (ECM) is crucial for the coordination and regulation of cell adhesion, recruitment, differentiation and death. Therefore, equilibrium between cell-cell and cell-matrix interactions and matrix-associated signals are important for the normal functioning of cells, as well as for regeneration. In this work, we describe importance of adhesive signals for myoblast cells’ growth and differentiation by generating a novel ECM mimetic peptide nanofiber scaffold system. We show that not only structure but also composition of bioactive signals are important for cell adhesion, growth and differentiation by mimicking the compositional and structural properties of native skeletal muscle basal lamina. We conjugated laminin-derived integrin binding peptide sequence, “IKVAV”, and fibronectin-derived well known adhesive sequence, “RGD”, into peptide nanostructures to provide adhesive and myogenic cues on a nanofibrous morphology. The myogenic and adhesive signals exhibited a synergistic effect on model myoblasts, C2C12 cells. Our results showed that self-assembled peptide nanofibers presenting laminin derived epitopes support adhesion, growth and proliferation of the cells and significantly promote the expression of skeletal muscle-specific marker genes. The functional peptide nanofibers used in this study present a biocompatible and biodegradable microenvironment, which is capable of supporting the growth and differentiation of C2C12 myoblasts into myotubes. PMID:26555958

  20. Carbohydrate-Mimetic Peptides for Pan Anti-Tumor Responses

    PubMed Central

    Kieber-Emmons, Thomas; Saha, Somdutta; Pashov, Anastas; Monzavi-Karbassi, Behjatolah; Murali, Ramachandran

    2014-01-01

    Molecular mimicry is fundamental to biology and transcends to many disciplines ranging from immune pathology to drug design. Structural characterization of molecular partners has provided insight into the origins and relative importance of complementarity in mimicry. Chemical complementarity is easy to understand; amino acid sequence similarity between peptides, for example, can lead to cross-reactivity triggering similar reactivity from their cognate receptors. However, conformational complementarity is difficult to decipher. Molecular mimicry of carbohydrates by peptides is often considered one of those. Extensive studies of innate and adaptive immune responses suggests the existence of carbohydrate mimicry, but the structural basis for this mimicry yields confounding details; peptides mimicking carbohydrates in some cases fail to exhibit both chemical and conformational mimicry. Deconvolution of these two types of complementarity in mimicry and its relationship to biological function can nevertheless lead to new therapeutics. Here, we discuss our experience examining the immunological aspects and implications of carbohydrate–peptide mimicry. Emphasis is placed on the rationale, the lessons learned from the methodologies to identify mimics, a perspective on the limitations of structural analysis, the biological consequences of mimicking tumor-associated carbohydrate antigens, and the notion of reverse engineering to develop carbohydrate-mimetic peptides in vaccine design strategies to induce responses to glycan antigens expressed on cancer cells. PMID:25071769

  1. Short Peptide Type I Interferon Mimetics: Therapeutics for Experimental Allergic Encephalomyelitis, Melanoma, and Viral Infections

    PubMed Central

    Ahmed, Chulbul M.

    2014-01-01

    The classical canonical model of interferon (IFN) signaling focuses solely on the activation of STAT transcription factors, which limits the model in terms of specific gene activation, associated epigenetic events, and IFN mimetic development. Accordingly, we have developed a noncanonical model of IFN signaling and report the development of short type I IFN peptide mimetic peptides based on the model. The mimetics, human IFNα1(152–189), human IFNβ(150–187), and ovine IFNτ(156–195) are derived from the C-terminus of the parent IFNs and function intracellularly based on the noncanonical model. Vaccinia virus produces a decoy IFN receptor (B18R) that inhibits type I IFN, but the IFN mimetics bypass B18R for effective antiviral activity. By contrast, both parent IFNs and mimetics inhibited vesicular stomatitis virus. The mimetics also possessed anti-tumor activity against murine melanoma B16 tumor cells in culture and in mice, including synergizing with suppressor of cytokine signaling 1 antagonist. Finally, the mimetics were potent therapeutics against experimental allergic encephalomyelitis, a mouse model of multiple sclerosis. The mimetics lack toxic side effects of the parent IFNs and, thus, are a potent therapeutic replacement of IFNs as therapeutics. PMID:24811478

  2. Moving a Carbohydrate Mimetic Peptide into the clinic

    PubMed Central

    Makhoul, Issam; Hutchins, Laura; Emanuel, Peter D; Pennisi, Angela; Siegel, Eric; Jousheghany, Fariba; Monzavi-Karbassi, Behjatolah; Kieber-Emmons, Thomas

    2014-01-01

    Tumor-Associated Carbohydrate Antigens (TACAs) are broad-spectrum targets for immunotherapy. Immunization with Carbohydrate Mimetic Peptides (CMPs) is a strategy to induce broad-spectrum TACA-reactive antibodies hypothesized to interfere with cellular pathways involved in tumor cell survival. A Phase I study was conducted with a first-in-man CMP referred to as P10s, conjugated to the Pan T cell carrier PADRE, along with MONTANIDE™ ISA 51 VG as adjuvant over a course of 5 immunizations. While designed as a safety and tolerability study, the potential for therapeutic impact was observed in a subject with metastatic lesions as evaluated before and after vaccine treatment. The subject received Vinorelbine and Trastuzumab (VT) for two months prior to study eligibility. PET scans showed partial response in the lungs and complete resolution of a previously enlarged subpectoral lymph node. Immunization with P10s vaccine resulted in responses to P10s, with serum and plasma antibodies reactive with and cytotoxic to human breast cancer cells in vitro, including the Trastuzumab-resistant HCC1954 cell line. However, the patient developed cystic masses in the brain parenchyma with no apparent evidence of metastases. The subject was switched to Docetaxel, Pertuzumab and Trastuzumab a year later, and her last PET scan showed a complete response in the lungs and lymph nodes. Incubation of cancer cells with a combination of vaccine-induced serum and docetaxel suggests that the induced antibodies sensitize tumor cells for more efficient killing upon administration of docetaxel. The data suggest that P10s-PADRE induces anti-tumor antibody response that in combination with chemotherapy can affect metastatic lesions in breast cancer patients. PMID:25483513

  3. Hierachical assembly of collagen mimetic peptides into biofunctional materials

    NASA Astrophysics Data System (ADS)

    Gleaton, Jeremy W.

    Collagen is a remarkably strong and prevalent protein distributed throughout nature and as such, collagen is an ideal material for a variety of medical applications. Research efforts for the development of synthetic collagen biomaterials is an area of rapid growth. Here we present two methods for the assembly of collagen mimetic peptides (CMPs). The initial approach prompts assembly of CMPs which contain modifications for metal ion-triggered assembly. Hierarchical assembly into triple helices, followed by formation of disks via hydrophobic interactions has been demonstrated. Metal-ion mediated assembly of these disks, using iron (II)-bipyrdine interactions, has been shown to form micron-sized cages. The nature of the final structures that form depends on the number of bipyridine moieties incorporated into the CMP. These hollow spheres encapsulate a range of molecular weight fluorescently labeled dextrans. Furthermore, they demonstrate a time dependent release of contents under a variety of thermal conditions. The second approach assembles CMPs via the copper-catalyzed alkyne-azide cycloaddition (CuAAC) and the strain-promoted alkyne-azide cycloaddition (SPAAC) reactions. CMPs that incorporate the unnatural amino acids L-propargylglycine and L-azidolysine form triple helices and demonstrate higher order assembly when reacted via CuAAC. Reaction of the alkyne/azide modified CMPs under CuAAC conditions was found to produce an crosslinked 3-dimensional network. Moreover, we demonstrate that polymers, such as, PEG, can be reacted with alkyne and azide CMP triple helices via CuAAC and SPAAC. This designed covalent CMP chemistry allows for high flexibility in integrating various chemical cues, such as cell growth and differentiation within the higher order structures.

  4. A Novel Peptide Thrombopoietin Mimetic Designing and Optimization Using Computational Approach

    PubMed Central

    Singh, Vimal Kishor; Kumar, Neeraj; Kalsan, Manisha; Saini, Abhishek; Chandra, Ramesh

    2016-01-01

    Thrombopoietin receptor (TPOR) is a cytokine receptor protein present on the cell surface. The activation of TPOR by thrombopoietin (TPO) (a glycoprotein hormone) triggers an intracellular cascade of megakaryocytopoiesis for the formation of platelets. Recent studies on ex vivo megakaryocytopoiesis have evolved the possibilities of therapeutics uses. These findings have paved the way for the development of various TPO alternatives (recombinant TPO, peptide, and non-peptide TPO mimetics), which are useful in regenerative medicine. However, these alternatives possess various limitations such as induction of autoimmune effects, high production cost, low specificity, and hence activity. In the present study, a novel peptidic TPO mimetic was designed through computational studies by studying the binding sites of TPO and TMP to TPOR and analogs of known mimetics. Screening of combinatorial library was done through molecular docking using ClusPro. These studies indicated mimetic-9 as a significant molecule since it was found to have better binding score of −938.8 kcal/mol with seven hydrogen bonds and a high number of hydrophobic interactions, than known mimetic TMP with docking score of −798.4 kcal/mol and TMP dimer with docking score of −811.9 kcal/mol for TPOR. Mimetic9-TPOR complex was further assessed by the molecular dynamics simulation, and their complex was found to be stable with an RMSD value of 0.091 Å. While studying the parameters, mimetic-9 was found to have overall good physiochemical properties with positive grand average hydropathy (GRAVY) score and high instability index score and was found to be localized in the extracellular region. The designed mimetic-9 might prove to be a useful lead molecule for mimicking the role of TPO for in vitro platelet production with higher efficiency.

  5. Signal transduction mechanism of a peptide mimetic of interferon-gamma.

    PubMed

    Subramaniam, Prem S; Flowers, Lawrence O; Haider, S Mohammed I; Johnson, Howard M

    2004-05-11

    The C-terminus of interferon-gamma (IFNgamma) contains a nuclear localization sequence (NLS) required for the activation and nuclear translocation of the transcription factor STAT1alpha and induction of IFNgamma-activated genes. On the basis of this and other studies, we developed a peptide mimetic of IFNgamma that possesses the IFNgamma functions of antiviral activity and upregulation of MHC class II molecules. The mimetic also shares with IFNgamma the ability to induce the activation and nuclear translocation of STAT1alpha and the IFNgamma receptor (IFNGR)-1 subunit. The mimetic, IFNgamma(95-132), is a peptide that consists of the C-terminal residues 95-132 of murine IFNgamma and contains a required alpha-helical domain and the NLS of IFNgamma. In this study, we determined the mechanism of the intracellular action of the mimetic at the level of signal transduction. We show that the mimetic mediates the nuclear transport of IFNGR-1 through its interaction with IFNGR-1 cytoplasmic region 253-287 via both the helical region and the NLS of IFNgamma(95-132). Alanine substitutions of the NLS of the mimetic showed that the NLS was required for nuclear translocation and that the nuclear transport properties of the mimetic correlated with its ability to bind IFNGR-1. These data also show that the NLS of IFNgamma(95-132) can interact simultaneously with IFNGR-1 and the nuclear import machinery. We found that in in vitro nuclear transport assays tyrosine-phosphorylated STAT1alpha failed to undergo nuclear translocation in the presence of nuclear import factors, but was transported to nucleus in the presence of IFNgamma(95-132) and JAK2-phosphorylated IFNGR-1, to which STAT1alpha binds, as a complex of IFNgamma(95-132)/IFNGR-1/STAT1alpha. Thus, the mimetic, which possesses IFNgamma function, is directly involved as a chaperone in the nuclear transport of STAT1alpha and shares this mechanism of action with that previously described for IFNgamma. The mimetic, like IFNgamma, is

  6. Student-Driven Design of Peptide Mimetics: Microwave-Assisted Synthesis of Peptoid Oligomers

    ERIC Educational Resources Information Center

    Pohl, Nicola L. B.; Kirshenbaum, Kent; Yoo, Barney; Schulz, Nathan; Zea, Corbin J.; Streff, Jennifer M.; Schwarz, Kimberly L.

    2011-01-01

    An experiment for the undergraduate organic laboratory is described in which peptide mimetic oligomers called "peptoids" are built stepwise on a solid-phase resin. Students employ two modern strategies to facilitate rapid multistep syntheses: solid-phase techniques to obviate the need for intermediate purifications and microwave irradiation to…

  7. A simple contact mapping algorithm for identifying potential peptide mimetics in protein–protein interaction partners

    PubMed Central

    Krall, Alex; Brunn, Jonathan; Kankanala, Spandana; Peters, Michael H

    2014-01-01

    A simple, static contact mapping algorithm has been developed as a first step at identifying potential peptide biomimetics from protein interaction partner structure files. This rapid and simple mapping algorithm, “OpenContact” provides screened or parsed protein interaction files based on specified criteria for interatomic separation distances and interatomic potential interactions. The algorithm, which uses all-atom Amber03 force field models, was blindly tested on several unrelated cases from the literature where potential peptide mimetics have been experimentally developed to varying degrees of success. In all cases, the screening algorithm efficiently predicted proposed or potential peptide biomimetics, or close variations thereof, and provided complete atom-atom interaction data necessary for further detailed analysis and drug development. In addition, we used the static parsing/mapping method to develop a peptide mimetic to the cancer protein target, epidermal growth factor receptor. In this case, secondary, loop structure for the peptide was indicated from the intra-protein mapping, and the peptide was subsequently synthesized and shown to exhibit successful binding to the target protein. The case studies, which all involved experimental peptide drug advancement, illustrate many of the challenges associated with the development of peptide biomimetics, in general. Proteins 2014; 82:2253–2262. © 2014 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc. PMID:24756879

  8. Glycosaminoglycan-Mimetic Signals Direct the Osteo/Chondrogenic Differentiation of Mesenchymal Stem Cells in a Three-Dimensional Peptide Nanofiber Extracellular Matrix Mimetic Environment.

    PubMed

    Arslan, Elif; Guler, Mustafa O; Tekinay, Ayse B

    2016-04-11

    Recent efforts in bioactive scaffold development focus strongly on the elucidation of complex cellular responses through the use of synthetic systems. Designing synthetic extracellular matrix (ECM) materials must be based on understanding of cellular behaviors upon interaction with natural and artificial scaffolds. Hence, due to their ability to mimic both the biochemical and mechanical properties of the native tissue environment, supramolecular assemblies of bioactive peptide nanostructures are especially promising for development of bioactive ECM-mimetic scaffolds. In this study, we used glycosaminoglycan (GAG) mimetic peptide nanofiber gel as a three-dimensional (3D) platform to investigate how cell lineage commitment is altered by external factors. We observed that amount of fetal bovine serum (FBS) presented in the cell media had synergistic effects on the ability of GAG-mimetic nanofiber gel to mediate the differentiation of mesenchymal stem cells into osteogenic and chondrogenic lineages. In particular, lower FBS concentration in the culture medium was observed to enhance osteogenic differentiation while higher amount FBS promotes chondrogenic differentiation in tandem with the effects of the GAG-mimetic 3D peptide nanofiber network, even in the absence of externally administered growth factors. We therefore demonstrate that mesenchymal stem cell differentiation can be specifically controlled by the combined influence of growth medium components and a 3D peptide nanofiber environment. PMID:26840042

  9. Bioactive Mimetics of Conotoxins and other Venom Peptides

    PubMed Central

    Duggan, Peter J.; Tuck, Kellie L.

    2015-01-01

    Ziconotide (Prialt®), a synthetic version of the peptide ω-conotoxin MVIIA found in the venom of a fish-hunting marine cone snail Conus magnus, is one of very few drugs effective in the treatment of intractable chronic pain. However, its intrathecal mode of delivery and narrow therapeutic window cause complications for patients. This review will summarize progress in the development of small molecule, non-peptidic mimics of Conotoxins and a small number of other venom peptides. This will include a description of how some of the initially designed mimics have been modified to improve their drug-like properties. PMID:26501323

  10. Bioactive Mimetics of Conotoxins and other Venom Peptides.

    PubMed

    Duggan, Peter J; Tuck, Kellie L

    2015-10-01

    Ziconotide (Prialt®), a synthetic version of the peptide ω-conotoxin MVIIA found in the venom of a fish-hunting marine cone snail Conus magnus, is one of very few drugs effective in the treatment of intractable chronic pain. However, its intrathecal mode of delivery and narrow therapeutic window cause complications for patients. This review will summarize progress in the development of small molecule, non-peptidic mimics of Conotoxins and a small number of other venom peptides. This will include a description of how some of the initially designed mimics have been modified to improve their drug-like properties. PMID:26501323

  11. A biologically active peptide mimetic of N-acetylgalactosamine/galactose

    PubMed Central

    Eggink, Laura L; Hoober, J Kenneth

    2009-01-01

    Background Glycosylated proteins and lipids are important regulatory factors whose functions can be altered by addition or removal of sugars to the glycan structure. The glycans are recognized by sugar-binding lectins that serve as receptors on the surface of many cells and facilitate initiation of an intracellular signal that changes the properties of the cells. We identified a peptide that mimics the ligand of an N-acetylgalactosamine (GalNAc)-specific lectin and asked whether the peptide would express specific biological activity. Findings A 12-mer phage display library was screened with a GalNAc-specific lectin to identify an amino acid sequence that binds to the lectin. Phage particles that were eluted from the lectin with free GalNAc were considered to have been bound to a GalNAc-binding site. Peptides were synthesized with the selected sequence as a quadravalent structure to facilitate receptor crosslinking. Treatment of human peripheral blood mononuclear cells for 24 h with the peptide stimulated secretion of interleukin-8 (IL-8) but not of IL-1β, IL-6, IL-10, or tumor necrosis factor-α (TNF-α). The secretion of IL-21 was stimulated as strongly with the peptide as with interferon-γ. Conclusion The data indicate that the quadravalent peptide has biological activity with a degree of specificity. These effects occurred at concentrations in the nanomolar range, in contrast to free sugars that generally bind to proteins in the micro- to millimolar range. PMID:19284521

  12. Molecular Design, Structures, and Activity of Antimicrobial Peptide-Mimetic Polymers

    PubMed Central

    Takahashi, Haruko; Palermo, Edmund F.; Yasuhara, Kazuma; Caputo, Gregory A.

    2014-01-01

    There is an urgent need for new antibiotics which are effective against drug-resistant bacteria without contributing to resistance development. We have designed and developed antimicrobial copolymers with cationic amphiphilic structures based on the mimicry of naturally occurring antimicrobial peptides. These copolymers exhibit potent antimicrobial activity against a broad spectrum of bacteria including methicillin-resistant Staphylococcus aureus with no adverse hemolytic activity. Notably, these polymers also did not result in any measurable resistance development in E. coli. The peptide-mimetic design principle offers significant flexibility and diversity in the creation of new antimicrobial materials and their potential biomedical applications. PMID:23832766

  13. A novel apolipoprotein C-II mimetic peptide that activates lipoprotein lipase and decreases serum triglycerides in apolipoprotein E-knockout mice.

    PubMed

    Amar, Marcelo J A; Sakurai, Toshihiro; Sakurai-Ikuta, Akiko; Sviridov, Denis; Freeman, Lita; Ahsan, Lusana; Remaley, Alan T

    2015-02-01

    Apolipoprotein A-I (apoA-I) mimetic peptides are currently being developed as possible new agents for the treatment of cardiovascular disease based on their ability to promote cholesterol efflux and their other beneficial antiatherogenic properties. Many of these peptides, however, have been reported to cause transient hypertriglyceridemia due to inhibition of lipolysis by lipoprotein lipase (LPL). We describe a novel bihelical amphipathic peptide (C-II-a) that contains an amphipathic helix (18A) for binding to lipoproteins and stimulating cholesterol efflux as well as a motif based on the last helix of apolipoprotein C-II (apoC-II) that activates lipolysis by LPL. The C-II-a peptide promoted cholesterol efflux from ATP-binding cassette transporter ABCA1-transfected BHK cells similar to apoA-I mimetic peptides. Furthermore, it was shown in vitro to be comparable to the full-length apoC-II protein in activating lipolysis by LPL. When added to serum from a patient with apoC-II deficiency, it restored normal levels of LPL-induced lipolysis and also enhanced lipolysis in serum from patients with type IV and V hypertriglyceridemia. Intravenous injection of C-II-a (30 mg/kg) in apolipoprotein E-knockout mice resulted in a significant reduction of plasma cholesterol and triglycerides of 38 ± 6% and 85 ± 7%, respectively, at 4 hours. When coinjected with the 5A peptide (60 mg/kg), the C-II-a (30 mg/kg) peptide was found to completely block the hypertriglyceridemic effect of the 5A peptide in C57Bl/6 mice. In summary, C-II-a is a novel peptide based on apoC-II, which promotes cholesterol efflux and lipolysis and may therefore be useful for the treatment of apoC-II deficiency and other forms of hypertriglyceridemia. PMID:25395590

  14. A Novel Apolipoprotein C-II Mimetic Peptide That Activates Lipoprotein Lipase and Decreases Serum Triglycerides in Apolipoprotein E–Knockout Mice

    PubMed Central

    Sakurai, Toshihiro; Sakurai-Ikuta, Akiko; Sviridov, Denis; Freeman, Lita; Ahsan, Lusana; Remaley, Alan T.

    2015-01-01

    Apolipoprotein A-I (apoA-I) mimetic peptides are currently being developed as possible new agents for the treatment of cardiovascular disease based on their ability to promote cholesterol efflux and their other beneficial antiatherogenic properties. Many of these peptides, however, have been reported to cause transient hypertriglyceridemia due to inhibition of lipolysis by lipoprotein lipase (LPL). We describe a novel bihelical amphipathic peptide (C-II-a) that contains an amphipathic helix (18A) for binding to lipoproteins and stimulating cholesterol efflux as well as a motif based on the last helix of apolipoprotein C-II (apoC-II) that activates lipolysis by LPL. The C-II-a peptide promoted cholesterol efflux from ATP-binding cassette transporter ABCA1-transfected BHK cells similar to apoA-I mimetic peptides. Furthermore, it was shown in vitro to be comparable to the full-length apoC-II protein in activating lipolysis by LPL. When added to serum from a patient with apoC-II deficiency, it restored normal levels of LPL-induced lipolysis and also enhanced lipolysis in serum from patients with type IV and V hypertriglyceridemia. Intravenous injection of C-II-a (30 mg/kg) in apolipoprotein E–knockout mice resulted in a significant reduction of plasma cholesterol and triglycerides of 38 ± 6% and 85 ± 7%, respectively, at 4 hours. When coinjected with the 5A peptide (60 mg/kg), the C-II-a (30 mg/kg) peptide was found to completely block the hypertriglyceridemic effect of the 5A peptide in C57Bl/6 mice. In summary, C-II-a is a novel peptide based on apoC-II, which promotes cholesterol efflux and lipolysis and may therefore be useful for the treatment of apoC-II deficiency and other forms of hypertriglyceridemia. PMID:25395590

  15. Peptide mimetics of the thrombin-bound structure of fibrinopeptide A.

    PubMed Central

    Nakanishi, H; Chrusciel, R A; Shen, R; Bertenshaw, S; Johnson, M E; Rydel, T J; Tulinsky, A; Kahn, M

    1992-01-01

    Recent work has suggested that the thrombin-bound conformation of fibrinopeptide A exhibits a strand-turn-strand motif, with a beta-turn centered at residues Glu-11 and Gly-12. Our molecular modeling analysis indicates that the published fibrinopeptide conformation cannot bind reasonably to thrombin but that reorientation of two residues by alignment with bovine pancreatic trypsin inhibitor provides a good fit within the deep thrombin cleft and satisfies all of the experimental nuclear Overhauser effect data. Based on this analysis, we have successfully designed and synthesized hybrid peptide mimetic substrates and inhibitors that mimic the proposed beta-turn structure. The results indicate that the turn conformation is an important aspect of thrombin specificity and that our turn mimetic design successfully mimics the thrombin-bound conformation of fibrinopeptide. Images PMID:1542664

  16. The action of mimetic peptides on connexins protects fibroblasts from the negative effects of ischemia reperfusion

    PubMed Central

    Glass, Beverley J.; Hu, Rebecca G.; Phillips, Anthony R. J.; Becker, David L.

    2015-01-01

    ABSTRACT Connexins have been proposed as a target for therapeutic treatment of a variety of conditions. The main approaches have been by antisense or small peptides specific against connexins. Some of these peptides enhance communication while others interfere with connexin binding partners or bind to the intracellular and extracellular loops of connexins. Here, we explored the mechanism of action of a connexin mimetic peptide by evaluating its effect on gap junction channels, connexin protein levels and hemichannel activity in fibroblast cells under normal conditions and following ischemia reperfusion injury which elevates Cx43 levels, increases hemichannel activity and causes cell death. Our results showed that the effects of the mimetic peptide were concentration-dependent. High concentrations (100-300 μM) significantly reduced Cx43 protein levels and GJIC within 2 h, while these effects did not appear until 6 h when using lower concentrations (10-30 μM). Cell death can be reduced when hemichannel opening and GJIC were minimised. PMID:26471768

  17. Combining Basal Insulin Analogs with Glucagon-Like Peptide-1 Mimetics

    PubMed Central

    2011-01-01

    Abstract Basal insulin analogs are recognized as an effective method of achieving and maintaining glycemic control for patients with type 2 diabetes. However, the progressive nature of the disease means that some individuals may require additional ways to maintain their glycemic goals. Intensification in these circumstances has traditionally been achieved by the addition of short-acting insulin to cover postprandial glucose excursions that are not targeted by basal insulin. However, intensive insulin regimens are associated with a higher risk of hypoglycemia and weight gain, which can contribute to a greater burden on patients. The combination of basal insulin with a glucagon-like peptide-1 (GLP-1) mimetic is a potentially attractive solution to this problem for some patients with type 2 diabetes. GLP-1 mimetics target postprandial glucose and should complement the activity of basal insulins; they are also associated with a relatively low risk of associated hypoglycemia and moderate, but significant, weight loss. Although the combination has not been approved by regulatory authorities, preliminary evidence from mostly small-scale studies suggests that basal insulins in combination with GLP-1 mimetics do provide improvements in A1c and postprandial glucose with concomitant weight loss and no marked increase in the risk of hypoglycemia. These results are promising, but further studies are required, including comparisons with basal–bolus therapy, before the complex value of this association can be fully appreciated. PMID:21711120

  18. Self-Assembling Glucagon-Like Peptide 1-Mimetic Peptide Amphiphiles for Enhanced Activity and Proliferation of Insulin-Secreting Cells

    PubMed Central

    Khan, Saahir; Sur, Shantanu; Newcomb, Christina J.; Appelt, Elizabeth A.

    2012-01-01

    Current treatment for type 1 diabetes mellitus requires daily insulin injections that fail to produce physiological glycemic control. Islet cell transplantation has been proposed as a permanent cure but is limited by loss of β-cell viability and function. These limitations could potentially be overcome by relying on the activity of glucagon-like peptide 1 (GLP-1), which acts on β-cells to promote insulin release, proliferation, and survival. We have developed a peptide amphiphile (PA) molecule incorporating a peptide mimetic for GLP-1. This GLP-1-mimetic PA self-assembles into one-dimensional nanofibers that stabilize the active secondary structure of GLP-1 and can be cross-linked by calcium ions to form a macroscopic gel capable of cell encapsulation and 3-dimensional culture. The GLP-1-mimetic PA nanofibers were found to stimulate insulin secretion from rat insulinoma (RINm5f) cells to a significantly greater extent than the mimetic peptide alone and to a level equivalent to that of the clinically used agonist exendin-4. The activity of the GLP-1-mimetic PA is glucose-dependent, lipid-raft dependent, and partially PKA-dependent consistent with native GLP-1. The GLP-1-mimetic PA also completely abrogates inflammatory cytokine-induced cell death to the level of untreated controls. When used as a PA gel to encapsulate RINm5f cells, the GLP-1-mimetic PA stimulates insulin secretion and proliferation in a cytokine-resistant manner that is significantly greater than a non-bioactive PA gel containing exendin-4. Due to its self-assembling property and bioactivity, the GLP-1-mimetic PA can be incorporated into previously developed islet cell transplantation protocols with the potential for significant enhancement of β-cell viability and function. PMID:22342354

  19. Thioredoxin-mimetic peptides (TXM) reverse auranofin induced apoptosis and restore insulin secretion in insulinoma cells.

    PubMed

    Cohen-Kutner, Moshe; Khomsky, Lena; Trus, Michael; Aisner, Yonatan; Niv, Masha Y; Benhar, Moran; Atlas, Daphne

    2013-04-01

    The thioredoxin reductase/thioredoxin system (TrxR/Trx1) plays a major role in protecting cells from oxidative stress. Disruption of the TrxR-Trx1 system keeps Trx1 in the oxidized state leading to cell death through activation of the ASK1-Trx1 apoptotic pathway. The potential mechanism and ability of tri- and tetra-oligopeptides derived from the canonical -CxxC- motif of the Trx1-active site to mimic and enhance Trx1 cellular activity was examined. The Trx mimetics peptides (TXM) protected insulinoma INS 832/13 cells from oxidative stress induced by selectively inhibiting TrxR with auranofin (AuF). TXM reversed the AuF-effects preventing apoptosis, and increasing cell-viability. The TXM peptides were effective in inhibiting AuF-induced MAPK, JNK and p38(MAPK) phosphorylation, in correlation with preventing caspase-3 cleavage and thereby PARP-1 dissociation. The ability to form a disulfide-bridge-like conformation was estimated from molecular dynamics simulations. The TXM peptides restored insulin secretion and displayed Trx1 denitrosylase activity. Their potency was 10-100-fold higher than redox reagents like NAC, AD4, or ascorbic acid. Unable to reverse ERK1/2 phosphorylation, TXM-CB3 (NAc-Cys-Pro-Cys amide) appeared to function in part, through inhibiting ASK1-Trx dissociation. These highly effective anti-apoptotic effects of Trx1 mimetic peptides exhibited in INS 832/13 cells could become valuable in treating adverse oxidative-stress related disorders such as diabetes. PMID:23327993

  20. Collagen-mimetic peptide-modifiable hydrogels for articular cartilage regeneration.

    PubMed

    Parmar, Paresh A; Chow, Lesley W; St-Pierre, Jean-Philippe; Horejs, Christine-Maria; Peng, Yong Y; Werkmeister, Jerome A; Ramshaw, John A M; Stevens, Molly M

    2015-06-01

    Regenerative medicine strategies for restoring articular cartilage face significant challenges to recreate the complex and dynamic biochemical and biomechanical functions of native tissues. As an approach to recapitulate the complexity of the extracellular matrix, collagen-mimetic proteins offer a modular template to incorporate bioactive and biodegradable moieties into a single construct. We modified a Streptococcal collagen-like 2 protein with hyaluronic acid (HA) or chondroitin sulfate (CS)-binding peptides and then cross-linked with a matrix metalloproteinase 7 (MMP7)-sensitive peptide to form biodegradable hydrogels. Human mesenchymal stem cells (hMSCs) encapsulated in these hydrogels exhibited improved viability and significantly enhanced chondrogenic differentiation compared to controls that were not functionalized with glycosaminoglycan-binding peptides. Hydrogels functionalized with CS-binding peptides also led to significantly higher MMP7 gene expression and activity while the HA-binding peptides significantly increased chondrogenic differentiation of the hMSCs. Our results highlight the potential of this novel biomaterial to modulate cell-mediated processes and create functional tissue engineered constructs for regenerative medicine applications. PMID:25907054

  1. Collagen-mimetic peptide-modifiable hydrogels for articular cartilage regeneration

    PubMed Central

    Parmar, Paresh A.; Chow, Lesley W.; St-Pierre, Jean-Philippe; Horejs, Christine-Maria; Peng, Yong Y.; Werkmeister, Jerome A.; Ramshaw, John A.M.; Stevens, Molly M.

    2015-01-01

    Regenerative medicine strategies for restoring articular cartilage face significant challenges to recreate the complex and dynamic biochemical and biomechanical functions of native tissues. As an approach to recapitulate the complexity of the extracellular matrix, collagen-mimetic proteins offer a modular template to incorporate bioactive and biodegradable moieties into a single construct. We modified a Streptococcal collagen-like 2 protein with hyaluronic acid (HA) or chondroitin sulfate (CS)-binding peptides and then cross-linked with a matrix metalloproteinase 7 (MMP7)-sensitive peptide to form biodegradable hydrogels. Human mesenchymal stem cells (hMSCs) encapsulated in these hydrogels exhibited improved viability and significantly enhanced chondrogenic differentiation compared to controls that were not functionalized with glycosaminoglycan-binding peptides. Hydrogels functionalized with CS-binding peptides also led to significantly higher MMP7 gene expression and activity while the HA-binding peptides significantly increased chondrogenic differentiation of the hMSCs. Our results highlight the potential of this novel biomaterial to modulate cell-mediated processes and create functional tissue engineered constructs for regenerative medicine applications. PMID:25907054

  2. Improving pancreatic islet in vitro functionality and transplantation efficiency by using heparin mimetic peptide nanofiber gels.

    PubMed

    Uzunalli, Gozde; Tumtas, Yasin; Delibasi, Tuncay; Yasa, Oncay; Mercan, Sercan; Guler, Mustafa O; Tekinay, Ayse B

    2015-08-01

    Pancreatic islet transplantation is a promising treatment for type 1 diabetes. However, viability and functionality of the islets after transplantation are limited due to loss of integrity and destruction of blood vessel networks. Thus, it is important to provide a proper mechanically and biologically supportive environment for enhancing both in vitro islet culture and transplantation efficiency. Here, we demonstrate that heparin mimetic peptide amphiphile (HM-PA) nanofibrous network is a promising platform for these purposes. The islets cultured with peptide nanofiber gel containing growth factors exhibited a similar glucose stimulation index as that of the freshly isolated islets even after 7 days. After transplantation of islets to STZ-induced diabetic rats, 28 day-long monitoring displayed that islets that were transplanted in HM-PA nanofiber gels maintained better blood glucose levels at normal levels compared to the only islet transplantation group. In addition, intraperitoneal glucose tolerance test revealed that animals that were transplanted with islets within peptide gels showed a similar pattern with the healthy control group. Histological assessment showed that islets transplanted within peptide nanofiber gels demonstrated better islet integrity due to increased blood vessel density. This work demonstrates that using the HM-PA nanofiber gel platform enhances the islets function and islet transplantation efficiency both in vitro and in vivo. PMID:25931015

  3. Impact of peptide clustering on unbinding forces in the context of fusion mimetics

    SciTech Connect

    Pähler, Gesa; Lorenz, Bärbel; Janshoff, Andreas

    2013-01-18

    Highlights: ► Coiled-coil peptides as SNARE mimetics for membrane fusion. ► Interaction forces assessed by colloidal probe microscopy. ► Lateral organization of lipopeptides visualized by atomic force microscopy. -- Abstract: Coiled-coil zipping and unzipping is a pivotal process in SNARE-regulated membrane fusion. In this study we examine this process mediated by a minimal model for coiled-coil formation employing force spectroscopy in the context of membrane-coated surfaces and probes. The interaction forces of several hundred pN are surprisingly low considering the proposed amount of molecular bonds in the contact zone. However, by means of high-resolution imaging employing atomic force microscopy and studying the lateral mobility of lipids and peptides as a function of coiled-coil formation, we are able to supply a detailed view on processes occurring on the membrane surfaces during force measurements. The interaction forces determined here are not only dependent on the peptide concentration on the surface, but also on the regional organization of lateral peptide clusters found prior to coiled-coil formation.

  4. Collagen-binding VEGF mimetic peptide: Structure, matrix interaction, and endothelial cell activation

    NASA Astrophysics Data System (ADS)

    Chan, Tania R.

    Long term survival of artificial tissue constructs depends greatly on proper vascularization. In nature, differentiation of endothelial cells and formation of vasculature are directed by dynamic spatio-temporal cues in the extracellular matrix that are difficult to reproduce in vitro. In this dissertation, we present a novel bifunctional peptide that mimics matrix-bound vascular endothelial growth factor (VEGF), which can be used to encode spatially controlled angiogenic signals in collagen-based scaffolds. The peptide, QKCMP, contains a collagen mimetic domain (CMP) that binds to type I collagen by a unique triple helix hybridization mechanism and a VEGF mimetic domain (QK) with pro-angiogenic activity. We demonstrate QKCMP's ability to hybridize with native and heat denatured collagens through a series of binding studies on collagen and gelatin substrates. Circular dichroism experiments show that the peptide retains the triple helical structure vital for collagen binding, and surface plasmon resonance study confirms the molecular interaction between the peptide and collagen strands. Cell culture studies demonstrate QKCMP's ability to induce endothelial cell morphogenesis and network formation as a matrix-bound factor in 2D and 3D collagen scaffolds. We also show that the peptide can be used to spatially modify collagen-based substrates to promote localized endothelial cell activation and network formation. To probe the biological events that govern these angiogenic cellular responses, we investigated the cell signaling pathways activated by collagen-bound QKCMP and determined short and long-term endothelial cell response profiles for p38, ERK1/2, and Akt signal transduction cascades. Finally, we present our efforts to translate the peptide's in vitro bioactivity to an in vivo burn injury animal model. When implanted at the wound site, QKCMP functionalized biodegradable hydrogels induce enhanced neovascularization in the granulation tissue. The results show QKCMP

  5. Nanoparticle Assembly and Gelatin Binding Mediated by Triple Helical Collagen Mimetic Peptide.

    PubMed

    San, Boi Hoa; Li, Yang; Tarbet, E Bart; Yu, S Michael

    2016-08-10

    Peptide-conjugated nanoparticles (NPs) have promising potential for applications in biosensing, diagnosis, and therapeutics because of their appropriate size, unique self-assembly, and specific substrate-binding properties. However, controlled assembly and selective target binding are difficult to achieve with simple peptides on NP surfaces because high surface energy makes NPs prone to self-aggregate and adhere nonspecifically. Here, we report the self-assembly and gelatin binding properties of collagen mimetic peptide (CMP) conjugated gold NPs (CMP-NPs). We show that the orientation of CMPs displayed on the NP surface can control NP assembly either by promoting or hindering triple helical folding between CMPs of neighboring NPs. We also show that CMP-NPs can specifically bind to denatured collagen by forming triple-helical hybrids between denatured collagen strands and CMPs, demonstrating their potential use for detection and selective removal of gelatin from protein mixtures. CMP conjugated NPs offer a simple and effective method for NP assembly and for targeting denatured collagens with high specificity. Therefore, they may lead to new types of functional nanomaterials for detection and study of denatured collagen associated with diseases characterized by high levels of collagen degradation. PMID:27403657

  6. Structure of the nociceptin/orphanin FQ receptor in complex with a peptide mimetic

    SciTech Connect

    Thompson, Aaron A.; Liu, Wei; Chun, Eugene; Katritch, Vsevolod; Wu, Huixian; Vardy, Eyal; Huang, Xi-Ping; Trapella, Claudio; Guerrini, Remo; Calo, Girolamo; Roth, Bryan L.; Cherezov, Vadim; Stevens, Raymond C.

    2012-07-11

    Members of the opioid receptor family of G-protein-coupled receptors (GPCRs) are found throughout the peripheral and central nervous system, where they have key roles in nociception and analgesia. Unlike the 'classical' opioid receptors, {delta}, {kappa} and {mu} ({delta}-OR, {kappa}-OR and {mu}-OR), which were delineated by pharmacological criteria in the 1970s and 1980s, the nociceptin/orphanin FQ (N/OFQ) peptide receptor (NOP, also known as ORL-1) was discovered relatively recently by molecular cloning and characterization of an orphan GPCR. Although it shares high sequence similarity with classical opioid GPCR subtypes ({approx}60%), NOP has a markedly distinct pharmacology, featuring activation by the endogenous peptide N/OFQ, and unique selectivity for exogenous ligands. Here we report the crystal structure of human NOP, solved in complex with the peptide mimetic antagonist compound-24 (C-24) (ref. 4), revealing atomic details of ligand-receptor recognition and selectivity. Compound-24 mimics the first four amino-terminal residues of the NOP-selective peptide antagonist UFP-101, a close derivative of N/OFQ, and provides important clues to the binding of these peptides. The X-ray structure also shows substantial conformational differences in the pocket regions between NOP and the classical opioid receptors {kappa} (ref. 5) and {mu} (ref. 6), and these are probably due to a small number of residues that vary between these receptors. The NOP-compound-24 structure explains the divergent selectivity profile of NOP and provides a new structural template for the design of NOP ligands.

  7. Annexin A1 mimetic peptide controls the inflammatory and fibrotic effects of silica particles in mice

    PubMed Central

    Trentin, P G; Ferreira, T P T; Arantes, A C S; Ciambarella, B T; Cordeiro, R S B; Flower, R J; Perretti, M; Martins, M A; Silva, P M R

    2015-01-01

    Background and Purpose Endogenous glucocorticoids are pro-resolving mediators, an example of which is the endogenous glucocorticoid-regulated protein annexin A1 (ANXA1). Because silicosis is an occupational lung disease characterized by unabated inflammation and fibrosis, in this study we tested the therapeutic properties of the N-terminal ANXA1-derived peptide annexin 1-(2-26) (Ac2-26) on experimental silicosis. Experimental Approach Swiss-Webster mice were administered silica particles intranasally and were subsequently treated with intranasal peptide Ac2-26 (200 μg per mouse) or dexamethasone (25 μg per mouse) for 7 days, starting 6 h post-challenge. Ac2-26 abolished the leukocyte infiltration, collagen deposition, granuloma formation and generation of pro-inflammatory cytokines evoked by silica; these variables were only partially inhibited by dexamethasone. Key Results A clear exacerbation of the silica-induced pathological changes was observed in ANXA1 knockout mice as compared with their wild-type (WT) littermate controls. Incubation of lung fibroblasts from WT mice with Ac2-26 in vitro reduced IL-13 or TGF-β-induced production of CCL2 (MCP-1) and collagen, but this peptide did not affect the production of CCL2 (MCP-1) by stimulated fibroblasts from formyl peptide receptor type 1 (FPR1) knockout mice. Ac2-26 also inhibited the production of CCL2 (MCP-1) from fibroblasts of FPR2 knockout mice. Conclusions and Implications Collectively, our findings reveal novel protective properties of the ANXA1 derived peptide Ac2-26 on the inflammatory and fibrotic responses induced by silica, and suggest that ANXA1 mimetic agents might be a promising strategy as innovative anti-fibrotic approaches for the treatment of silicosis. PMID:25659822

  8. Thioredoxin-mimetic peptides as catalysts of S-denitrosylation and anti-nitrosative stress agents.

    PubMed

    Kronenfeld, Gali; Engelman, Rotem; Weisman-Shomer, Pnina; Atlas, Daphne; Benhar, Moran

    2015-02-01

    S-nitrosylation, the coupling of a nitric oxide moiety to a reactive cysteine residue to form an S-nitrosothiol (SNO), is an important posttranslational mechanism for regulating protein activity. Growing evidence indicates that hyper-S-nitrosylation may contribute to cellular dysfunction associated with various human diseases. It is also increasingly appreciated that thioredoxin and thioredoxin reductase play significant roles in the cellular catabolism of SNO and protection from nitrosative stress. Here, we investigated the SNO reductase activity and protective effects of thioredoxin-mimetic peptides (TXMs), Ac-Cys-Pro-Cys-amide (CB3) and Ac-Cys-Gly-Pro-Cys-amide (CB4), both under cell-free conditions and in nitrosatively stressed cultured cells. In vitro biochemical analyses revealed that the TXM peptides reduced small-molecule SNO compounds, such as S-nitrosoglutathione (GSNO), and acted as general and efficient protein-denitrosylating agents. In particular, CB3 was found to be a highly potent SNO-metabolizing agent. Notably, CB3 mimicked the activity of thioredoxin by coupling with thioredoxin reductase to enhance GSNO reduction. Moreover, in a cell-free lysate system, both CB3 and CB4 synergized with an NADPH-dependent activity to denitrosylate proteins. Further investigation revealed that the TXM peptides protect the peroxiredoxin-thioredoxin system from SNO-dependent inhibition. Indeed, SNO-inhibited Prx1 was efficiently denitrosylated and reactivated by CB3 or CB4. In addition, CB3 protected thioredoxin reductase from SNO-mediated inactivation both in vitro and in intact cells. Finally, CB3 and CB4 partially rescued human neuroblastoma SH-SY5Y cells and rat insulinoma INS-1 832/13 cells from GSNO-induced growth inhibition. Collectively, the present findings indicate the efficient denitrosylation activity and protective effects of TXM peptides and suggest their potential therapeutic value in treating pathological conditions related to nitrosative stress

  9. Non-Covalent Photo-Patterning of Gelatin Matrices Using Caged Collagen Mimetic Peptides

    PubMed Central

    Li, Yang; Hoa San, Boi; L. Kessler, Julian; Hwan Kim, Jin; Xu, Qingguo; Hanes, Justin; Yu, Seungju Michael

    2015-01-01

    Advancements in photolithography have enabled us to spatially encode biochemical cues in biocompatible platforms such as synthetic hydrogels. Conventional patterning works through photo-activated chemical reactions on inert polymer networks. However, these techniques cannot be directly applied to protein hydrogels without chemically altering the protein scaffolds. To this end, we developed a non-covalent photo-patterning strategy for gelatin (denatured collagen) hydrogels utilizing a caged collagen mimetic peptide (caged CMP) which binds to gelatin strands through UV activated, triple helix hybridization. Here we present 2D and 3D photo-patterning of gelatin hydrogels enabled by the caged CMPs as well as creation of concentration gradients of CMPs. We show that photo-patterning of PEG-conjugated caged CMPs can be used to spatially control cell adhesion on gelatin films. CMP’s specificity for binding to gelatin allows patterning of almost any synthetic or natural gelatin-containing matrix, such as zymograms, gelatin-methacrylate hydrogels, and even a corneal tissue. Since the CMP is a chemically and biologically inert peptide which is proven to be an ideal carrier for bioactive molecules, our patterning method provides a radically new tool for immobilizing drugs to natural tissues and for functionalizing scaffolds for complex tissue formation. PMID:25476588

  10. Coating of biomaterial scaffolds with the collagen-mimetic peptide GFOGER for bone defect repair.

    PubMed

    Wojtowicz, Abigail M; Shekaran, Asha; Oest, Megan E; Dupont, Kenneth M; Templeman, Kellie L; Hutmacher, Dietmar W; Guldberg, Robert E; García, Andrés J

    2010-03-01

    Healing large bone defects and non-unions remains a significant clinical problem. Current treatments, consisting of auto and allografts, are limited by donor supply and morbidity, insufficient bioactivity and risk of infection. Biotherapeutics, including cells, genes and proteins, represent promising alternative therapies, but these strategies are limited by technical roadblocks to biotherapeutic delivery, cell sourcing, high cost, and regulatory hurdles. In the present study, the collagen-mimetic peptide, GFOGER, was used to coat synthetic PCL scaffolds to promote bone formation in critically-sized segmental defects in rats. GFOGER is a synthetic triple helical peptide that binds to the alpha(2)beta(1) integrin receptor involved in osteogenesis. GFOGER coatings passively adsorbed onto polymeric scaffolds, in the absence of exogenous cells or growth factors, significantly accelerated and increased bone formation in non-healing femoral defects compared to uncoated scaffolds and empty defects. Despite differences in bone volume, no differences in torsional strength were detected after 12 weeks, indicating that bone mass but not bone quality was improved in this model. This work demonstrates a simple, cell/growth factor-free strategy to promote bone formation in challenging, non-healing bone defects. This biomaterial coating strategy represents a cost-effective and facile approach, translatable into a robust clinical therapy for musculoskeletal applications. PMID:20056517

  11. Coating of Biomaterial Scaffolds with the Collagen-Mimetic Peptide GFOGER for Bone Defect Repair

    PubMed Central

    Wojtowicz, Abigail M.; Shekaran, Asha; Oest, Megan E.; Dupont, Kenneth M.; Templeman, Kellie L.; Hutmacher, Dietmar W.; Guldberg, Robert E.; García, Andrés J.

    2009-01-01

    Healing large bone defects and non-unions remains a significant clinical problem. Current treatments, consisting of auto- and allografts, are limited by donor supply and morbidity, insufficient bioactivity and risk of infection. Biotherapeutics, including cells, genes and proteins, represent promising alternative therapies, but these strategies are limited by technical roadblocks to biotherapeutic delivery, cell sourcing, high cost, and regulatory hurdles. In the present study, the collagen-mimetic peptide, GFOGER, was used to coat synthetic PCL scaffolds to promote bone formation in critically-sized segmental defects in rats. GFOGER is a synthetic triple helical peptide that binds to the α2β1 integrin receptor involved in osteogenesis. GFOGER coatings passively-adsorbed onto polymeric scaffolds, in the absence of exogenous cells or growth factors, significantly accelerated and increased bone formation in non-healing femoral defects compared to uncoated scaffolds and empty defects. Despite differences in bone volume, no differences in torsional strength were detected after 12 weeks, indicating that bone mass but not bone quality was improved in this model. This work demonstrates a simple, cell/growth factor-free strategy to promote bone formation in challenging, non-healing bone defects. This biomaterial coating strategy represents a cost effective and facile approach translatable into a robust clinical therapy for musculoskeletal applications. PMID:20056517

  12. Treatment of Mild Traumatic Brain Injury with an Erythropoietin-Mimetic Peptide

    PubMed Central

    Garcia, Robert; Sujit Kumar Gaddam, Samson; Grill, Raymond J.; Cerami Hand, Carla; Siva Tian, Tian; Hannay, H. Julia

    2013-01-01

    Abstract Mild traumatic brain injury (mTBI) results in an estimated 75–90% of the 1.7 million TBI-related emergency room visits each year. Post-concussion symptoms, which can include impaired memory problems, may persist for prolonged periods of time in a fraction of these cases. The purpose of this study was to determine if an erythropoietin-mimetic peptide, pyroglutamate helix B surface peptide (pHBSP), would improve neurological outcomes following mTBI. Sixty-four rats were randomly assigned to pHBSP or control (inactive peptide) 30 μg/kg IP every 12 h for 3 days, starting at either 1 hour (early treatment) or 24 h (delayed treatment), after mTBI (cortical impact injury 3 m/sec, 2.5 mm deformation). Treatment with pHBSP resulted in significantly improved performance on the Morris water maze task. Rats that received pHBSP required 22.3±1.3 sec to find the platform, compared to 26.3±1.3 sec in control rats (p=0.022). The rats that received pHBSP also traveled a significantly shorter distance to get to the platform, 5.0±0.3 meters, compared to 6.1±0.3 meters in control rats (p=0.019). Motor tasks were only transiently impaired in this mTBI model, and no treatment effect on motor performance was observed with pHBSP. Despite the minimal tissue injury with this mTBI model, there was significant activation of inflammatory cells identified by labeling with CD68, which was reduced in the pHBSP-treated animals. The results suggest that pHBSP may improve cognitive function following mTBI. PMID:22827443

  13. Thioredoxin-mimetic peptide CB3 lowers MAPKinase activity in the Zucker rat brain.

    PubMed

    Cohen-Kutner, Moshe; Khomsky, Lena; Trus, Michael; Ben-Yehuda, Hila; Lenhard, James M; Liang, Yin; Martin, Tonya; Atlas, Daphne

    2014-01-01

    Diabetes is a high risk factor for dementia. High glucose may be a risk factor for dementia even among persons without diabetes, and in transgenic animals it has been shown to cause a potentiation of indices that are pre-symptomatic of Alzheimer's disease. To further elucidate the underlying mechanisms linking inflammatory events elicited in the brain during oxidative stress and diabetes, we monitored the activation of mitogen-activated kinsase (MAPKs), c-jun NH2-terminal kinase (JNK), p38 MAP kinases (p38(MAPK)), and extracellular activating kinsae1/2 (ERK1/2) and the anti-inflammatory effects of the thioredoxin mimetic (TxM) peptides, Ac-Cys-Pro-Cys-amide (CB3) and Ac-Cys-Gly-Pro-Cys-amide (CB4) in the brain of male leptin-receptor-deficient Zucker diabetic fatty (ZDF) rats and human neuroblastoma SH-SY5Y cells. Daily i.p. injection of CB3 to ZDF rats inhibited the phosphorylation of JNK and p38(MAPK), and prevented the expression of thioredoxin-interacting-protein (TXNIP/TBP-2) in ZDF rat brain. Although plasma glucose/insulin remained high, CB3 also increased the phosphorylation of AMP-ribose activating kinase (AMPK) and inhibited p70(S6K) kinase in the brain. Both CB3 and CB4 reversed apoptosis induced by inhibiting thioredoxin reductase as monitored by decreasing caspase 3 cleavage and PARP dissociation in SH-SY5Y cells. The decrease in JNK and p38(MAPK) activity in the absence of a change in plasma glucose implies a decrease in oxidative or neuroinflammatory stress in the ZDF rat brain. CB3 not only attenuated MAPK phosphorylation and activated AMPK in the brain, but it also diminished apoptotic markers, most likely acting via the MAPK-AMPK-mTOR pathway. These results were correlated with CB3 and CB4 inhibiting inflammation progression and protection from oxidative stress induced apoptosis in human neuronal cells. We suggest that by attenuating neuro-inflammatory processes in the brain Trx1 mimetic peptides could become beneficial for preventing neurological

  14. Thioredoxin-mimetic peptide CB3 lowers MAPKinase activity in the Zucker rat brain☆

    PubMed Central

    Cohen-Kutner, Moshe; Khomsky, Lena; Trus, Michael; Ben-Yehuda, Hila; Lenhard, James M.; Liang, Yin; Martin, Tonya; Atlas, Daphne

    2014-01-01

    Diabetes is a high risk factor for dementia. High glucose may be a risk factor for dementia even among persons without diabetes, and in transgenic animals it has been shown to cause a potentiation of indices that are pre-symptomatic of Alzheimer's disease. To further elucidate the underlying mechanisms linking inflammatory events elicited in the brain during oxidative stress and diabetes, we monitored the activation of mitogen-activated kinsase (MAPKs), c-jun NH2-terminal kinase (JNK), p38 MAP kinases (p38MAPK), and extracellular activating kinsae1/2 (ERK1/2) and the anti-inflammatory effects of the thioredoxin mimetic (TxM) peptides, Ac-Cys-Pro-Cys-amide (CB3) and Ac-Cys-Gly-Pro-Cys-amide (CB4) in the brain of male leptin-receptor-deficient Zucker diabetic fatty (ZDF) rats and human neuroblastoma SH-SY5Y cells. Daily i.p. injection of CB3 to ZDF rats inhibited the phosphorylation of JNK and p38MAPK, and prevented the expression of thioredoxin-interacting-protein (TXNIP/TBP-2) in ZDF rat brain. Although plasma glucose/insulin remained high, CB3 also increased the phosphorylation of AMP-ribose activating kinase (AMPK) and inhibited p70S6K kinase in the brain. Both CB3 and CB4 reversed apoptosis induced by inhibiting thioredoxin reductase as monitored by decreasing caspase 3 cleavage and PARP dissociation in SH-SY5Y cells. The decrease in JNK and p38MAPK activity in the absence of a change in plasma glucose implies a decrease in oxidative or neuroinflammatory stress in the ZDF rat brain. CB3 not only attenuated MAPK phosphorylation and activated AMPK in the brain, but it also diminished apoptotic markers, most likely acting via the MAPK–AMPK–mTOR pathway. These results were correlated with CB3 and CB4 inhibiting inflammation progression and protection from oxidative stress induced apoptosis in human neuronal cells. We suggest that by attenuating neuro-inflammatory processes in the brain Trx1 mimetic peptides could become beneficial for preventing neurological

  15. Thioredoxin-Mimetic-Peptides Protect Cognitive Function after Mild Traumatic Brain Injury (mTBI)

    PubMed Central

    Baratz-Goldstein, Renana; Deselms, Hanna; Heim, Leore Raphael; Khomski, Lena; Hoffer, Barry J.

    2016-01-01

    Mild traumatic brain injury (mTBI) is recognized as a common injury among children, sportsmen, and elderly population. mTBI lacks visible objective structural brain damage but patients frequently suffer from long-lasting cognitive, behavioral and emotional difficulties associated with biochemical and cellular changes. Currently there is no effective treatment for patients with mTBI. The thioredoxin reductase/thioredoxin pathway (TrxR/Trx1) has both anti-inflammatory and anti-oxidative properties. If the system is compromised, Trx1 remains oxidized and triggers cell death via an ASK1-Trx1 signal transduction mechanism. We previously showed tri and tetra peptides which were derived from the canonical -CxxC- motif of the Trx1-active site, called thioredoxin mimetic (TXM) peptides, reversed inflammatory and oxidative stress damage mimicking Trx1 activity. Here, TXM-peptides were examined for protecting cognitive function following weight drop closed-head injury in a mouse model of mTBI. TXM-CB3 (AcCys-Pro-CysNH2), TXM-CB13 (DY-70; AcCys-Met-Lys-CysNH2) or AD4 (ACysNH2) were administered at 50 mg/kg, 60 min after injury and cognitive performance was monitored by the novel-object-recognition and Y-maze tests. Behavioral deficits subsequent to mTBI injury were reversed by a single dose of TXM-CB3, TXM-CB13 and, to a lesser extent, by AD4. TXM-CB13 similar to TXM-CB3 and AD4 reversed oxidative stress-induced phosphorylation of mitogen-activated kinases, p38MAPK and c-Jun N-terminal kinase, (JNK) in human neuronal SH-SY5Y cells. We conclude that significantly improved cognitive behavior post mTBI by the TXM-peptides could result from anti-apoptotic, and/or anti-inflammatory activities. Future preclinical studies are required to establish the TXM-peptides as potential therapeutic drugs for brain injuries. PMID:27285176

  16. Thioredoxin-Mimetic-Peptides Protect Cognitive Function after Mild Traumatic Brain Injury (mTBI).

    PubMed

    Baratz-Goldstein, Renana; Deselms, Hanna; Heim, Leore Raphael; Khomski, Lena; Hoffer, Barry J; Atlas, Daphne; Pick, Chaim G

    2016-01-01

    Mild traumatic brain injury (mTBI) is recognized as a common injury among children, sportsmen, and elderly population. mTBI lacks visible objective structural brain damage but patients frequently suffer from long-lasting cognitive, behavioral and emotional difficulties associated with biochemical and cellular changes. Currently there is no effective treatment for patients with mTBI. The thioredoxin reductase/thioredoxin pathway (TrxR/Trx1) has both anti-inflammatory and anti-oxidative properties. If the system is compromised, Trx1 remains oxidized and triggers cell death via an ASK1-Trx1 signal transduction mechanism. We previously showed tri and tetra peptides which were derived from the canonical -CxxC- motif of the Trx1-active site, called thioredoxin mimetic (TXM) peptides, reversed inflammatory and oxidative stress damage mimicking Trx1 activity. Here, TXM-peptides were examined for protecting cognitive function following weight drop closed-head injury in a mouse model of mTBI. TXM-CB3 (AcCys-Pro-CysNH2), TXM-CB13 (DY-70; AcCys-Met-Lys-CysNH2) or AD4 (ACysNH2) were administered at 50 mg/kg, 60 min after injury and cognitive performance was monitored by the novel-object-recognition and Y-maze tests. Behavioral deficits subsequent to mTBI injury were reversed by a single dose of TXM-CB3, TXM-CB13 and, to a lesser extent, by AD4. TXM-CB13 similar to TXM-CB3 and AD4 reversed oxidative stress-induced phosphorylation of mitogen-activated kinases, p38MAPK and c-Jun N-terminal kinase, (JNK) in human neuronal SH-SY5Y cells. We conclude that significantly improved cognitive behavior post mTBI by the TXM-peptides could result from anti-apoptotic, and/or anti-inflammatory activities. Future preclinical studies are required to establish the TXM-peptides as potential therapeutic drugs for brain injuries. PMID:27285176

  17. PEG-Based Hydrogels with Collagen Mimetic Peptide-Mediated and Tunable Physical Crosslinks

    PubMed Central

    Stahl, Patrick J.; Romano, Nicole H.; Wirtz, Denis; Yu, S. Michael

    2010-01-01

    Mechanical properties of tissue scaffolds have major effects on the morphology and differentiation of cells. In contrast to two-dimensional substrates, local biochemical and mechanical properties of three-dimensional hydrogels are difficult to control due to the geometrical confinement. We designed synthetic 3D hydrogels featuring complexes of four-arm poly(ethylene glycol) (PEG) and collagen mimetic peptides (CMPs) that form hydrogels via physical crosslinks mediated by thermally reversible triple helical assembly of CMPs. Here we present the fabrication of various PEG-CMP 3D hydrogels and their local mechanical properties determined by particle tracking microrheology. Results show that CMP mediated physical crosslinks can be disrupted by altering the temperature of the gel or by adding free CMPs that compete for triple helix formation. This allowed modulation of both bulk and local stiffness as well as the creation of stiffness gradients within the PEG-CMP hydrogel, which demonstrates its potential as a novel scaffold for encoding physico-chemical signals for tissue formation. PMID:20715762

  18. New mimetic peptides inhibitors of Αβ aggregation. Molecular guidance for rational drug design.

    PubMed

    Barrera Guisasola, Exequiel E; Andujar, Sebastián A; Hubin, Ellen; Broersen, Kerensa; Kraan, Ivonne M; Méndez, Luciana; Delpiccolo, Carina M L; Masman, Marcelo F; Rodríguez, Ana M; Enriz, Ricardo D

    2015-05-01

    A new series of mimetic peptides possessing a significant Aβ aggregation modulating effect was reported here. These compounds were obtained based on a molecular modelling study which allowed us to perform a structural-based virtual selection. Monitoring Aβ aggregation by thioflavin T fluorescence and transmission electron microscopy revealed that fibril formation was significantly decreased upon prolonged incubation in presence of the active compounds. Dot blot analysis suggested a decrease of soluble oligomers strongly associated with cognitive decline in Alzheimer's disease. For the molecular dynamics simulations, we used an Aβ42 pentameric model where the compounds were docked using a blind docking technique. To analyze the dynamic behaviour of the complexes, extensive molecular dynamics simulations were carried out in explicit water. We also measured parameters or descriptors that allowed us to quantify the effect of these compounds as potential inhibitors of Aβ aggregation. Thus, significant alterations in the structure of our Aβ42 protofibril model were identified. Among others we observed the destruction of the regular helical twist, the loss of a stabilizing salt bridge and the loss of a stabilizing hydrophobic interaction in the β1 region. Our results may be helpful in the structural identification and understanding of the minimum structural requirements for these molecules and might provide a guide in the design of new aggregation modulating ligands. PMID:25805447

  19. Conformational assembly and biological properties of collagen mimetic peptides and their thermally responsive polymer conjugates

    NASA Astrophysics Data System (ADS)

    Krishna, Ohm Divyam

    2011-12-01

    Collagens are one of the most abundant proteins found in body tissues and organs, endowing structural integrity, mechanical strength, and multiple biological functions. Destabilized collagen inside human body leads to various degenerative diseases (ex. osteoarthritis) and ageing. This has continued to motivate the design of synthetic peptides and bio-synthetic polypeptides to closely mimic the native collagens in terms of triple helix structure and stability, potential for higher order assembly, and biological properties. However, the widespread application of de novo collagens has been limited in part by the need for hydroxylated proline in the formation of stable triple helical structures. To address this continued need, a hydroxyproline-free, thermally stable collagen-mimetic peptide (CLP-Cys) was rationally designed via the incorporation of electrostatically stabilized amino acid triplets. CLP-Cys was synthesized via solid phase peptide synthesis. The formation and stability of the triple helical structure were indicated via circular dichroism (CD) experiments and confirmed via differential scanning calorimetry (DSC) results. CLP-Cys also self-assembled into nano-rods and micro-fibrils, as evidenced via a combination of dynamic light scattering and transmission electron microscopy. Given the high thermal stability and its propensity for higher-order assembly, CLP-Cys was further functionalized at both the ends with a thermally responsive polymer, poly(diethylene glycol methyl ether methacrylate), (PDEGMEMA) to synthesize a biohybrid triblock copolymer. The CD results indicated that the triple helical form is retained, the thermal unfolding is sustained and helix to coil transition is reversible in the triblock hybrid context. The LCST of PDEGMEMA homopolymer (26 °C) is increased (to 35 °C) upon conjugation to the hydrophilic collagen peptide domain. Further, a combination of static light scattering, Cryo-SEM, TEM and confocal microscopy elucidated that the

  20. The essential role of annexin A1 mimetic peptide in the skin allograft survival.

    PubMed

    Teixeira, Rodrigo Antonio Parra; Mimura, Kallyne Kioko Oliveira; Araujo, Leandro Pires; Greco, Karin Vicente; Oliani, Sonia Maria

    2016-02-01

    Immunosuppressive drugs have a critical role in inhibiting tissue damage and allograft rejection. Studies have demonstrated the anti-inflammatory effects of the annexin A1 (AnxA1) in the regulation of transmigration and apoptosis of leucocytes. In the present study, an experimental skin allograft model was used to evaluate a potential protective effect of AnxA1 in transplantation survival. Mice were used for the skin allograft model and pharmacological treatments were carried out using either the AnxA1 mimetic peptide Ac2-26, with or without cyclosporine A (CsA), starting 3 days before surgery until rejection. Graft survival, skin histopathology, leucocyte transmigration and expression of AnxA1 and AnxA5 post-transplantation were analysed. Pharmacological treatment with Ac2-26 increased skin allograft survival related with inhibition of neutrophil transmigration and induction of apoptosis, thereby reducing the tissue damage compared with control animals. Moreover, AnxA1 and AnxA5 expression increased after Ac2-26 treatment in neutrophils. Interestingly, the combination of Ac2-26 and cyclosporine A showed similar survival of transplants when compared with the cyclosporine A group, which could be attributed to a synergistic effect of both drugs. Investigations in vitro revealed that cyclosporine A inhibited extracellular-signal-regulated kinase (ERK) phosphorylation induced by Ac2-26 in neutrophils. Overall, the results suggest that AnxA1 has an essential role in augmenting the survival of skin allograft, mainly owing to inhibition of neutrophil transmigration and enhancement of apoptosis. This effect may lead to the development of new therapeutic approaches relevant to transplant rejection. PMID:23897745

  1. Activity of antimicrobial peptide mimetics in the oral cavity: II. Activity against periopathogenic biofilms and anti-inflammatory activity.

    PubMed

    Hua, J; Scott, R W; Diamond, G

    2010-12-01

    Whereas periodontal disease is ultimately of bacterial etiology, from multispecies biofilms of gram-negative anaerobic microorganisms, much of the deleterious effects are caused by the resultant epithelial inflammatory response. Hence, development of a treatment that combines anti-biofilm antibiotic activity with anti-inflammatory activity would be of great utility. Antimicrobial peptides (AMPs) such as defensins are naturally occurring peptides that exhibit broad-spectrum activity as well as a variety of immunomodulatory activities. Furthermore, bacteria do not readily develop resistance to these agents. However, clinical studies have suggested that they do not represent optimal candidates for exogenous therapeutic agents. Small-molecule mimetics of these AMPs exhibit similar activities to the parent peptides, in addition to having low toxicity, high stability and low cost. To determine whether AMP mimetics have the potential for treatment of periodontal disease, we examined the activity of one mimetic, mPE, against biofilm cultures of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. Metabolic assays as well as culture and biomass measurement assays demonstrated that mPE exhibits potent activity against biofilm cultures of both species. Furthermore, as little as 2 μg ml(-1) mPE was sufficient to inhibit interleukin-1β-induced secretion of interleukin-8 in both gingival epithelial cells and THP-1 cells. This anti-inflammatory activity is associated with a reduction in activation of nuclear factor-κB, suggesting that mPE can act both as an anti-biofilm agent in an anaerobic environment and as an anti-inflammatory agent in infected tissues. PMID:21040516

  2. In Vivo and In Vitro Effects of an Apolipoprotein E Mimetic Peptide on Amyloid-β Pathology

    PubMed Central

    Handattu, Shaila P.; Monroe, Candyce E.; Nayyar, Gaurav; Palgunachari, Mayakonda N.; Kadish, Inga; van Groen, Thomas; Anantharamaiah, G.M.; Garber, David W.

    2014-01-01

    Background Apolipoprotein E (ApoE) is the major apolipoprotein present in the high-density lipoprotein-like particles in the central nervous system (CNS). ApoE is involved in various protective functions in CNS including cholesterol transport, anti-inflammatory, and antioxidant effects. An ApoE peptide would be expected to exert protective effects on neuroinflammation. Objective To determine the effects of an ApoE mimetic peptide Ac-hE18A-NH2 on amyloid-β pathology. Method Using human APP/PS1ΔE9 transgenic mice and in vitro studies, we have evaluated the effect of an ApoE mimetic peptide, Ac-hE18A-NH2, on amyloid plaque deposition and inflammation. Results Administration of Ac-hE18A-NH2 to APP/PS1ΔE9 mice for 6 weeks (50 μg/mouse, 3 times a week) significantly improved cognition with a concomitant decrease in amyloid plaque deposition and reduced activated microglia and astrocytes, and increased brain ApoE levels. Oligomeric Aβ42 (oAβ42) and oxidized PAPC (ox-PAPC) inhibited secretion of ApoE in U251 cells, a human astrocyte cell line, and this effect was ameliorated in the presence of peptide Ac-hE18A-NH2. The peptide also increased Aβ42 uptake in a cell line of human macrophages. Conclusions Peptide Ac-hE18A-NH2 attenuates the effects of oxidative stress on ApoE secretion, inhibits amyloid plaque deposition, and thus could be beneficial in the treatment of Alzheimer’s disease. PMID:23603398

  3. Fine-tuning the stimulation of MLL1 methyltransferase activity by a histone H3-based peptide mimetic

    SciTech Connect

    Avdic, Vanja; Zhang, Pamela; Lanouette, Sylvain; Voronova, Anastassia; Skerjanc, Ilona; Couture, Jean-Francois

    2011-08-24

    The SET1 family of methyltransferases carries out the bulk of histone H3 Lys-4 methylation in vivo. One of the common features of this family is the regulation of their methyltransferase activity by a tripartite complex composed of WDR5, RbBP5, and Ash2L. To selectively probe the role of the SET1 family of methyltransferases, we have developed a library of histone H3 peptide mimetics and report herein the characterization of an N{alpha} acetylated form of histone H3 peptide (N{alpha}H3). Binding and inhibition studies reveal that the addition of an acetyl moiety to the N terminus of histone H3 significantly enhances its binding to WDR5 and prevents the stimulation of MLL1 methyltransferase activity by the WDR5-RbBP5-Ash2L complex. The crystal structure of N{alpha}H3 in complex with WDR5 reveals that a high-affinity hydrophobic pocket accommodates the binding of the acetyl moiety. These results provide the structural basis to control WDR5-RbBP5-Ash2L-MLL1 activity and a tool to manipulate stem cell differentiation programs.-Avdic, V., Zhang, P., Lanouette, S., Voronova, A., Skerjanc, I., Couture, J.-F. Fine-tuning the stimulation of MLL1 methyltransferase activity by a histone H3-based peptide mimetic.

  4. Encoding physico-chemical cues in synthetic hydrogels by triple helix assembly of collagen mimetic peptides

    NASA Astrophysics Data System (ADS)

    Stahl, Patrick

    The ECM is a complex natural system evolved to promote proliferation and differentiation of cells during tissue development. In order to create synthetic biomaterials for studying cell-scaffold interactions and ultimately for engineering tissues, scientists strive to recapitulate many characteristics of ECM by developing hydrogels that contain mechanical cues and biochemical signals such as adhesion moieties and cell growth factors. While synthetic hydrogels bypass limitations of naturally-derived materials (e.g. transfer of pathogens), nature provides inspiration to enhance the functionality of synthetic hydrogels through biomimetic approaches. The collagen triple helix is the basis for the supramolecular structure of collagen in the ECM, and its adaptation in collagen mimetic peptides (CMPs) has provided hybridization mechanisms that can be employed in the formation and functionalization of synthetic hydrogels. The aim of this dissertation is to develop novel poly(ethylene glycol) (PEG)-based hydrogels that employ CMP triple helix assembly as a non-covalent yet target-specific tool to encode physical and chemical cues into the hydrogel with spatial control. We demonstrate that multi-arm PEG functionalized with CMPs form hydrogels supported by physical crosslinks mediated by CMP triple helix. Particle tracking microrheology shows that these physical crosslinks are sensitive to temperature as well as addition of exogenous CMPs that can disrupt crosslinks by competing for triple helix formation. This physical crosslink disruption enables the modulation of bulk hydrogel elasticity and the introduction of local stiffness gradients in PEG-CMP hydrogels. We also present photopolymerized PEG diacrylate (PEGDA) hydrogels displaying CMPs that can be further conjugated to CMPs with bioactive moieties via triple helix hybridization. Encoding these hydrogels with cell-adhesive CMPs induces cell spreading and proliferation. We further demonstrate generation of gradients and

  5. Identification and Characterization of a Peptide Mimetic That May Detect a Species of Disease-Associated Anticardiolipin Antibodies in Patients With the Antiphospholipid Syndrome

    PubMed Central

    Visvanathan, Sudha; Scott, Jamie K.; Hwang, Kwan-Ki; Banares, Michelle; Grossman, Jennifer M.; Merrill, Joan T.; FitzGerald, John; Chukwuocha, Reginald U.; Tsao, Betty P.; Hahn, Bevra H.; Chen, Pojen P.

    2007-01-01

    Objective To test the feasibility of applying a mimetic (specific for a patient-derived prothrombotic anticardiolipin antibody [aCL]) to study the homologous, disease-associated aCL in patients with antiphospholipid syndrome (APS). Methods We used the CL15 monoclonal aCL to screen 17 phage-display peptide libraries. Peptides (corresponding to recurrent peptide sequences) and their derivatives were synthesized and analyzed for binding to CL15 and for their abilities to inhibit CL15 from binding to cardiolipin. A peptide was chosen and used to study CL15-like IgG aCL in plasma samples from patients with APS, patients with systemic lupus erythematosus (SLE) but without APS, and normal healthy donors. Results Library screening with CL15 yielded 4 recurrent peptide sequences. Analyses of peptides showed that peptide CL154C reacted with antibody CL15 and inhibited binding of CL15 to cardiolipin, indicating that peptide CL154C may be a peptide mimetic for the CL15 aCL. Initial studies with plasma samples revealed that CL154C-reactive IgG was present (positivity defined as the mean + 3 SD optical density of the 25 normal controls) in 15 of 21 APS patients and 1 of 12 SLE patients. Conclusion These findings suggest that it is feasible to develop a specific enzyme-linked immunosorbent assay for each immunologically and functionally distinct disease-associated aCL. Additional testing of CL154C with a larger number of APS patients and SLE patients, as well as identification of peptide mimetics for each distinct aCL, will reveal the diagnostic potential of CL154C and other mimetics in identifying patients with aCL who are at risk of developing life-threatening thrombosis. PMID:12632428

  6. Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity

    PubMed Central

    Scarpi, D; Cirelli, D; Matrone, C; Castronovo, G; Rosini, P; Occhiato, E G; Romano, F; Bartali, L; Clemente, A M; Bottegoni, G; Cavalli, A; De Chiara, G; Bonini, P; Calissano, P; Palamara, A T; Garaci, E; Torcia, M G; Guarna, A; Cozzolino, F

    2012-01-01

    Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation, sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates. PMID:22764098

  7. Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity.

    PubMed

    Scarpi, D; Cirelli, D; Matrone, C; Castronovo, G; Rosini, P; Occhiato, E G; Romano, F; Bartali, L; Clemente, A M; Bottegoni, G; Cavalli, A; De Chiara, G; Bonini, P; Calissano, P; Palamara, A T; Garaci, E; Torcia, M G; Guarna, A; Cozzolino, F

    2012-01-01

    Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase 1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation,sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates. PMID:22951986

  8. Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity.

    PubMed

    Scarpi, D; Cirelli, D; Matrone, C; Castronovo, G; Rosini, P; Occhiato, E G; Romano, F; Bartali, L; Clemente, A M; Bottegoni, G; Cavalli, A; De Chiara, G; Bonini, P; Calissano, P; Palamara, A T; Garaci, E; Torcia, M G; Guarna, A; Cozzolino, F

    2012-01-01

    Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation, sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates. PMID:22764098

  9. Vaccination with peptide mimetics of the gp41 prehairpin fusion intermediate yields neutralizing antisera against HIV-1 isolates

    PubMed Central

    Bianchi, Elisabetta; Joyce, Joseph G.; Miller, Michael D.; Finnefrock, Adam C.; Liang, Xiaoping; Finotto, Marco; Ingallinella, Paolo; McKenna, Philip; Citron, Michael; Ottinger, Elizabeth; Hepler, Robert W.; Hrin, Renee; Nahas, Deborah; Wu, Chengwei; Montefiori, David; Shiver, John W.; Pessi, Antonello; Kim, Peter S.

    2010-01-01

    Eliciting a broadly neutralizing polyclonal antibody response against HIV-1 remains a major challenge. One approach to vaccine development is prevention of HIV-1 entry into cells by blocking the fusion of viral and cell membranes. More specifically, our goal is to elicit neutralizing antibodies that target a transient viral entry intermediate (the prehairpin intermediate) formed by the HIV-1 gp41 protein. Because this intermediate is transient, a stable mimetic is required to elicit an immune response. Previously, a series of engineered peptides was used to select a mAb (denoted D5) that binds to the surface of the gp41 prehairpin intermediate, as demonstrated by x-ray crystallographic studies. D5 inhibits the replication of HIV-1 clinical isolates, providing proof-of-principle for this vaccine approach. Here, we describe a series of peptide mimetics of the gp41 prehairpin intermediate designed to permit a systematic analysis of the immune response generated in animals. To improve the chances of detecting weak neutralizing polyclonal responses, two strategies were employed in the initial screening: use of a neutralization-hypersensitive virus and concentration of the IgG fraction from immunized animal sera. This allowed incremental improvements through iterative cycles of design, which led to vaccine candidates capable of generating a polyclonal antibody response, detectable in unfractionated sera, that neutralize tier 1 HIV-1 and simian HIV primary isolates in vitro. Our findings serve as a starting point for the design of more potent immunogens to elicit a broadly neutralizing response against the gp41 prehairpin intermediate. PMID:20483992

  10. A novel method for oral delivery of apolipoprotein mimetic peptides synthesized from all L-amino acids.

    PubMed

    Navab, Mohamad; Ruchala, Piotr; Waring, Alan J; Lehrer, Robert I; Hama, Susan; Hough, Greg; Palgunachari, Mayakonda N; Anantharamaiah, G M; Fogelman, Alan M

    2009-08-01

    Administered subcutaneously, D-4F or L-4F are equally efficacious, but only D-4F is orally efficacious because of digestion of L-4F by gut proteases. Orally administering niclosamide (a chlorinated salicylanilide used as a molluscicide, antihelminthic, and lampricide) in temporal proximity to oral L-4F (but not niclosamide alone) in apoE null mice resulted in significant improvement (P < 0.001) in the HDL-inflammatory index (HII), which measures the ability of HDL to inhibit LDL-induced monocyte chemotactic activity in endothelial cell cultures. Oral administration of L-[113-122]apoJ with niclosamide also resulted in significant improvement (P < 0.001) in HII. Oral administration of niclosamide and L-4F together with pravastatin to female apoE null mice at 9.5 months of age for six months significantly reduced aortic sinus lesion area (P = 0.02), en face lesion area (P = 0.033), and macrophage lesion area (P = 0.02) compared with pretreatment, indicating lesion regression. In contrast, lesions were significantly larger in mice receiving only niclosamide and pravastatin or L-4F and pravastatin (P < 0.001). In vitro niclosamide and L-4F tightly associated rendering the peptide resistant to trypsin digestion. Niclosamide itself did not inhibit trypsin activity. The combination of niclosamide with apolipoprotein mimetic peptides appears to be a promising method for oral delivery of these peptides. PMID:19225094

  11. A novel method for oral delivery of apolipoprotein mimetic peptides synthesized from all L-amino acids

    PubMed Central

    Navab, Mohamad; Ruchala, Piotr; Waring, Alan J.; Lehrer, Robert I.; Hama, Susan; Hough, Greg; Palgunachari, Mayakonda N.; Anantharamaiah, G. M.; Fogelman, Alan M.

    2009-01-01

    Administered subcutaneously, D-4F or L-4F are equally efficacious, but only D-4F is orally efficacious because of digestion of L-4F by gut proteases. Orally administering niclosamide (a chlorinated salicylanilide used as a molluscicide, antihelminthic, and lampricide) in temporal proximity to oral L-4F (but not niclosamide alone) in apoE null mice resulted in significant improvement (P < 0.001) in the HDL-inflammatory index (HII), which measures the ability of HDL to inhibit LDL-induced monocyte chemotactic activity in endothelial cell cultures. Oral administration of L-[113-122]apoJ with niclosamide also resulted in significant improvement (P < 0.001) in HII. Oral administration of niclosamide and L-4F together with pravastatin to female apoE null mice at 9.5 months of age for six months significantly reduced aortic sinus lesion area (P = 0.02), en face lesion area (P = 0.033), and macrophage lesion area (P = 0.02) compared with pretreatment, indicating lesion regression. In contrast, lesions were significantly larger in mice receiving only niclosamide and pravastatin or L-4F and pravastatin (P < 0.001). In vitro niclosamide and L-4F tightly associated rendering the peptide resistant to trypsin digestion. Niclosamide itself did not inhibit trypsin activity. The combination of niclosamide with apolipoprotein mimetic peptides appears to be a promising method for oral delivery of these peptides. PMID:19225094

  12. Peptide-Like Molecules (PLMs): A Journey from Peptide Bond Isosteres to Gramicidin S Mimetics and Mitochondrial Targeting Agents

    PubMed Central

    Wipf, Peter; Xiao, Jingbo; Stephenson, Corey R. J.

    2010-01-01

    Peptides are natural ligands and substrates for receptors and enzymes and exhibit broad physiological effects. However, their use as therapeutic agents often suffers from poor bioavailability and insufficient membrane permeability. The success of peptide mimicry hinges on the ability of bioisosteres, in particular peptide bond replacements, to adopt suitable secondary structures relevant to peptide strands and position functional groups in equivalent space. This perspective highlights past and ongoing studies in our group that involve new methods development as well as specific synthetic library preparations and applications in chemical biology, with the goal to enhance the use of alkene and cyclopropane peptide bond isosteres. PMID:20725595

  13. Thrombogenic collagen-mimetic peptides: Self-assembly of triple helix-based fibrils driven by hydrophobic interactions

    PubMed Central

    Cejas, Mabel A.; Kinney, William A.; Chen, Cailin; Vinter, Jeremy G.; Almond, Harold R.; Balss, Karin M.; Maryanoff, Cynthia A.; Schmidt, Ute; Breslav, Michael; Mahan, Andrew; Lacy, Eilyn; Maryanoff, Bruce E.

    2008-01-01

    Collagens are integral structural proteins in animal tissues and play key functional roles in cellular modulation. We sought to discover collagen model peptides (CMPs) that would form triple helices and self-assemble into supramolecular fibrils exhibiting collagen-like biological activity without preorganizing the peptide chains by covalent linkages. This challenging objective was accomplished by placing aromatic groups on the ends of a representative 30-mer CMP, (GPO)10, as with l-phenylalanine and l-pentafluorophenylalanine in 32-mer 1a. Computational studies on homologous 29-mers 1a′–d′ (one less GPO), as pairs of triple helices interacting head-to-tail, yielded stabilization energies in the order 1a′ > 1b′ > 1c′ > 1d′, supporting the hypothesis that hydrophobic aromatic groups can drive CMP self-assembly. Peptides 1a–d were studied comparatively relative to structural properties and ability to stimulate human platelets. Although each 32-mer formed stable triple helices (CD) spectroscopy, only 1a and 1b self-assembled into micrometer-scale fibrils. Light microscopy images for 1a depicted long collagen-like fibrils, whereas images for 1d did not. Atomic force microscopy topographical images indicated that 1a and 1b self-organize into microfibrillar species, whereas 1c and 1d do not. Peptides 1a and 1b induced the aggregation of human blood platelets with a potency similar to type I collagen, whereas 1c was much less effective, and 1d was inactive (EC50 potency: 1a/1b ≫ 1c > 1d). Thus, 1a and 1b spontaneously self-assemble into thrombogenic collagen-mimetic materials because of hydrophobic aromatic interactions provided by the special end-groups. These findings have important implications for the design of biofunctional CMPs. PMID:18559857

  14. Rapid Endolysosomal Escape and Controlled Intracellular Trafficking of Cell Surface Mimetic Quantum-Dots-Anchored Peptides and Glycopeptides.

    PubMed

    Tan, Roger S; Naruchi, Kentaro; Amano, Maho; Hinou, Hiroshi; Nishimura, Shin-Ichiro

    2015-09-18

    A novel strategy for the development of a high performance nanoparticules platform was established by means of cell surface mimetic quantum-dots (QDs)-anchored peptides/glycopeptides, which was developed as a model system for nanoparticle-based drug delivery (NDD) vehicles with defined functions helping the specific intracellular trafficking after initial endocytosis. In this paper, we proposed a standardized protocol for the preparation of multifunctional QDs that allows for efficient cellular uptake and rapid escaping from the endolysosomal system and subsequent cytoplasmic molecular delivery to the target cellular compartment. Chemoselective ligation of the ketone-functionalized hexahistidine derivative facilitated both efficient endocytic entry and rapid endolysosomal escape of the aminooxy/phosphorylcholine self-assembled monolayer-coated QDs (AO/PCSAM-QDs) to the cytosol in various cell lines such as human normal and cancer cells, while modifications of these QDs with cell-penetrating arginine-rich peptides showed poor cellular uptake and induced self-aggregation of AO/PCSAM-QDs. Combined use of hexahistidylated AO/PCSAM-QDs with serglycine-like glycopeptides, namely synthetic proteoglycan initiators (PGIs), elicited the entry and controlled intracellular trafficking, Golgi localization, and also excretion of these nanoparticles, which suggested that the present approach would provide an ideal platform for the design of high performance NDD systems. PMID:26107406

  15. Sera from Children with Autism Induce Autistic Features Which Can Be Rescued with a CNTF Small Peptide Mimetic in Rats

    PubMed Central

    Kazim, Syed Faraz; Cardenas-Aguayo, Maria del Carmen; Arif, Mohammad; Blanchard, Julie; Fayyaz, Fatima; Grundke-Iqbal, Inge; Iqbal, Khalid

    2015-01-01

    Autism is a neurodevelopmental disorder characterized clinically by impairments in social interaction and verbal and non-verbal communication skills as well as restricted interests and repetitive behavior. It has been hypothesized that altered brain environment including an imbalance in neurotrophic support during early development contributes to the pathophysiology of autism. Here we report that sera from children with autism which exhibited abnormal levels of various neurotrophic factors induced cell death and oxidative stress in mouse primary cultured cortical neurons. The effects of sera from autistic children were rescued by pre-treatment with a ciliary neurotrophic factor (CNTF) small peptide mimetic, Peptide 6 (P6), which was previously shown to exert its neuroprotective effect by modulating CNTF/JAK/STAT pathway and LIF signaling and by enhancing brain derived neurotrophic factor (BDNF) expression. Similar neurotoxic effects and neuroinflammation were observed in young Wistar rats injected intracerebroventricularly with autism sera within hours after birth. The autism sera injected rats demonstrated developmental delay and deficits in social communication, interaction, and novelty. Both the neurobiological changes and the behavioral autistic phenotype were ameliorated by P6 treatment. These findings implicate the involvement of neurotrophic imbalance during early brain development in the pathophysiology of autism and a proof of principle of P6 as a potential therapeutic strategy for autism. PMID:25769033

  16. Hydrogels functionalized with N-cadherin mimetic peptide enhance osteogenesis of hMSCs by emulating the osteogenic niche.

    PubMed

    Zhu, Meiling; Lin, Sien; Sun, Yuxin; Feng, Qian; Li, Gang; Bian, Liming

    2016-01-01

    N-cadherin is considered to be the key factor in directing cell-cell interactions during mesenchymal condensation, which is essential to osteogenesis. In this study, hyaluronic acid (HA) hydrogels are biofunctionalized with an N-cadherin mimetic peptide to mimic the pro-osteogenic niche in the endosteal space to promote the osteogenesis of human mesenchymal stem cells (hMSCs). Results show that the conjugation of the N-cadherin peptide in the HA hydrogels enhances the expression of the osteogenic marker genes in the seeded hMSCs. Furthermore, the biofunctionalized HA hydrogels promote the alkaline phosphatase activity, type I collagen deposition, and matrix mineralization by the seeded hMSCs under both in vitro and in vivo condition. We postulate that the biofunctionalized hydrogels emulates the N-cadherin-mediated homotypic cell-cell adhesion among MSCs and the "orthotypic" interaction between the osteoblasts and MSCs. These findings demonstrate that the biofunctionalized HA hydrogels provide a supportive niche microenvironment for the osteogenesis of hMSCs. PMID:26580785

  17. EPOR-Based Purification and Analysis of Erythropoietin Mimetic Peptides from Human Urine by Cys-Specific Cleavage and LC/MS/MS

    NASA Astrophysics Data System (ADS)

    Vogel, Matthias; Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2015-09-01

    The development of a new class of erythropoietin mimetic agents (EMA) for treating anemic conditions has been initiated with the discovery of oligopeptides capable of dimerizing the erythropoietin (EPO) receptor and thus stimulating erythropoiesis. The most promising amino acid sequences have been mounted on various different polymeric structures or carrier molecules to obtain highly active EPO-like drugs exhibiting beneficial and desirable pharmacokinetic profiles. Concomitant with creating new therapeutic options, erythropoietin mimetic peptide (EMP)-based drug candidates represent means to artificially enhance endurance performance and necessitate coverage by sports drug testing methods. Therefore, the aim of the present study was to develop a strategy for the comprehensive detection of EMPs in doping controls, which can be used complementary to existing protocols. Three model EMPs were used to provide proof-of-concept data. Following EPO receptor-facilitated purification of target analytes from human urine, the common presence of the cysteine-flanked core structure of EMPs was exploited to generate diagnostic peptides with the aid of a nonenzymatic cleavage procedure. Sensitive detection was accomplished by targeted-SIM/data-dependent MS2 analysis. Method characterization was conducted for the EMP-based drug peginesatide concerning specificity, linearity, precision, recovery, stability, ion suppression/enhancement, and limit of detection (LOD, 0.25 ng/mL). Additionally, first data for the identification of the erythropoietin mimetic peptides EMP1 and BB68 were generated, demonstrating the multi-analyte testing capability of the presented approach.

  18. Enzymatic Macrocyclization of 1,2,3‐Triazole Peptide Mimetics

    PubMed Central

    Oueis, Emilia; Jaspars, Marcel; Westwood, Nicholas J.

    2016-01-01

    Abstract The macrocyclization of linear peptides is very often accompanied by significant improvements in their stability and biological activity. Many strategies are available for their chemical macrocyclization, however, enzyme‐mediated methods remain of great interest in terms of synthetic utility. To date, known macrocyclization enzymes have been shown to be active on both peptide and protein substrates. Here we show that the macrocyclization enzyme of the cyanobactin family, PatGmac, is capable of macrocyclizing substrates with one, two, or three 1,4‐substituted 1,2,3‐triazole moieties. The introduction of non‐peptidic scaffolds into macrocycles is highly desirable in tuning the activity and physical properties of peptidic macrocycles. We have isolated and fully characterized nine non‐natural triazole‐containing cyclic peptides, a further ten molecules are also synthesized. PatGmac has now been shown to be an effective and versatile tool for the ring closure by peptide bond formation. PMID:27059105

  19. Inhibition of CD4+ T lymphocyte binding to fibronectin and immune-cell accumulation in inflammatory sites by non-peptidic mimetics of Arg-Gly-Asp.

    PubMed

    Hershkoviz, R; Greenspoon, N; Mekori, Y A; Hadari, R; Alon, R; Kapustina, G; Lider, O

    1994-02-01

    The Arg-Gly-Asp (RGD) cell adhesion motif has been demonstrated in various studies to play a pivotal role in leucocyte and platelet interactions with plasma and extracellular matrix (ECM) glycoproteins. The recognition of the RGD sequence is mediated by heterodimeric receptors designated integrins of the beta 1 subfamily, expressed on distinct cell types, including T lymphocytes. We have recently shown that flexible non-peptidic mimetics of RGD, in which the two ionic side groups were separated by a linear spacer of 11 atoms, bound specifically to the platelet integrin alpha 11b beta 3, and inhibited T cell-mediated immune responses. The present study was designed to (i) further characterize the structural requirements for RGD interactions with CD4+ T cells, and (ii) examine the mechanisms by which the RGD mimetics interfere with immune cell reactivity in vivo. We now report that freezing the conformational degrees of freedom in the spacer chain, which fixes the relative orientation of the guanidinium and carboxylate side groups in a favourable manner, results in a higher level of inhibition of T cell binding to immobilized fibronectin, an RGD-containing ECM glycoprotein. In vivo, treatment of mice with relatively low doses of the RGD mimetics, but not the RGD peptide, inhibited the elicitation of an adoptively transferred DTH reaction. This inhibition was achieved by direct impairment of the ability of antigen-primed lymph node cells to migrate and accumulate in inflammatory sites. Hence, we suggest that the design and production of non-peptidic mimetics of RGD offers a novel approach to study defined parameters related to the structure-function requirements of small adhesion epitopes. Furthermore, this approach could be used therapeutically to inhibit pathological processes which depend on RGD recognition. PMID:7905794

  20. Collagen-Gelatin Mixtures as Wound Model, and Substrates for VEGF-Mimetic Peptide Binding and Endothelial Cell Activation

    PubMed Central

    Chan, Tania R.; Stahl, Patrick J.; Li, Yang; Yu, S. Michael

    2015-01-01

    In humans, high level of collagen remodeling is seen during normal physiological events such as bone renewal, as well as in pathological conditions, such as arthritis, tumor growth and other chronic wounds. Our lab recently discovered that collagen mimetic peptide (CMP) is able to hybridize with denatured collagens at these collagen remodeling sites with high affinity. Here, we show that the CMP's high binding affinity to denatured collagens can be utilized to deliver angiogenic signals to scaffolds composed of heat-denatured collagens (gelatins). We first demonstrate hybridization between denatured collagens and QKCMP, a CMP with pro-angiogenic QK domain. We show that high levels of QKCMP can be immobilized to a new artificial matrix containing both fibrous type I collagen and heat denatured collagen through triple helix hybridization, and that the QKCMP is able to stimulate early angiogenic response of endothelial cells (ECs). We also show that the QKCMP can bind to excised tissues from burn injuries in cutaneous mouse model, suggesting its potential for promoting neovascularization of burn wounds. PMID:25584990

  1. Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides

    PubMed Central

    Li, Yang; Foss, Catherine A.; Pomper, Martin G.; Yu, S. Michael

    2014-01-01

    Collagen is a major structural component of the extracellular matrix that supports tissue formation and maintenance. Although collagen remodeling is an integral part of normal tissue renewal, excessive amount of remodeling activity is involved in tumors, arthritis, and many other pathological conditions. During collagen remodeling, the triple helical structure of collagen molecules is disrupted by proteases in the extracellular environment. In addition, collagens present in many histological tissue samples are partially denatured by the fixation and preservation processes. Therefore, these denatured collagen strands can serve as effective targets for biological imaging. We previously developed a caged collagen mimetic peptide (CMP) that can be photo-triggered to hybridize with denatured collagen strands by forming triple helical structure, which is unique to collagens. The overall goals of this procedure are i) to image denatured collagen strands resulting from normal remodeling activities in vivo, and ii) to visualize collagens in ex vivo tissue sections using the photo-triggered caged CMPs. To achieve effective hybridization and successful in vivo and ex vivo imaging, fluorescently labeled caged CMPs are either photo-activated immediately before intravenous injection, or are directly activated on tissue sections. Normal skeletal collagen remolding in nude mice and collagens in prefixed mouse cornea tissue sections are imaged in this procedure. The imaging method based on the CMP-collagen hybridization technology presented here could lead to deeper understanding of the tissue remodeling process, as well as allow development of new diagnostics for diseases associated with high collagen remodeling activity. PMID:24513868

  2. Insulin Mimetic Peptide Disrupts the Primary Binding Site of the Insulin Receptor.

    PubMed

    Lawrence, Callum F; Margetts, Mai B; Menting, John G; Smith, Nicholas A; Smith, Brian J; Ward, Colin W; Lawrence, Michael C

    2016-07-22

    Sets of synthetic peptides that interact with the insulin receptor ectodomain have been discovered by phage display and reported in the literature. These peptides were grouped into three classes termed Site 1, Site 2, and Site 3 based on their mutual competition of binding to the receptor. Further refinement has yielded, in particular, a 36-residue Site 2-Site 1 fusion peptide, S519, that binds the insulin receptor with subnanomolar affinity and exhibits agonist activity in both lipogenesis and glucose uptake assays. Here, we report three-dimensional crystallographic detail of the interaction of the C-terminal, 16-residue Site 1 component (S519C16) of S519 with the first leucine-rich repeat domain (L1) of the insulin receptor. Our structure shows that S519C16 binds to the same site on the L1 surface as that occupied by a critical component of the primary binding site, namely the helical C-terminal segment of the insulin receptor α-chain (termed αCT). In particular, the two phenylalanine residues within the FYXWF motif of S519C16 are seen to engage the insulin receptor L1 domain surface in a fashion almost identical to the respective αCT residues Phe(701) and Phe(705) The structure provides a platform for the further development of peptidic and/or small molecule agents directed toward the insulin receptor and/or the type 1 insulin-like growth factor receptor. PMID:27281820

  3. PHEX Mimetic (SPR4-Peptide) Corrects and Improves HYP and Wild Type Mice Energy-Metabolism

    PubMed Central

    Zelenchuk, Lesya V.; Hedge, Anne-Marie; Rowe, Peter S. N.

    2014-01-01

    Context PHEX or DMP1 mutations cause hypophosphatemic-rickets and altered energy metabolism. PHEX binds to DMP1-ASARM-motif to form a complex with α5β3 integrin that suppresses FGF23 expression. ASARM-peptides increase FGF23 by disrupting the PHEX-DMP1-Integrin complex. We used a 4.2 kDa peptide (SPR4) that binds to ASARM-peptide/motif to study the DMP1-PHEX interaction and to assess SPR4 for the treatment of energy metabolism defects in HYP and potentially other bone-mineral disorders. Design Subcutaneously transplanted osmotic pumps were used to infuse SPR4-peptide or vehicle (VE) into wild-type mice (WT) and HYP-mice (PHEX mutation) for 4 weeks. Results SPR4 partially corrected HYP mice hypophosphatemia and increased serum 1.25(OH)2D3. Serum FGF23 remained high and PTH was unaffected. WT-SPR4 mice developed hypophosphatemia and hypercalcemia with increased PTH, FGF23 and 1.25(OH)2D3. SPR4 increased GAPDH HYP-bone expression 60× and corrected HYP-mice hyperglycemia and hypoinsulinemia. HYP-VE serum uric-acid (UA) levels were reduced and SPR4 infusion suppressed UA levels in WT-mice but not HYP-mice. SPR4 altered leptin, adiponectin, and sympathetic-tone and increased the fat mass/weight ratio for HYP and WT mice. Expression of perlipin-2 a gene involved in obesity was reduced in HYP-VE and WT-SPR4 mice but increased in HYP-SPR4 mice. Also, increased expression of two genes that inhibit insulin-signaling, ENPP1 and ESP, occurred with HYP-VE mice. In contrast, SPR4 reduced expression of both ENPP1 and ESP in WT mice and suppressed ENPP1 in HYP mice. Increased expression of FAM20C and sclerostin occurred with HYP-VE mice. SPR4 suppressed expression of FAM20C and sclerostin in HYP and WT mice. Conclusions ASARM peptides and motifs are physiological substrates for PHEX and modulate osteocyte PHEX-DMP1-α5β3-integrin interactions and thereby FGF23 expression. These interactions also provide a nexus that regulates bone and energy metabolism. SPR4 suppression of

  4. Alpha-turn mimetics: short peptide alpha-helices composed of cyclic metallopentapeptide modules.

    PubMed

    Kelso, Michael J; Beyer, Renée L; Hoang, Huy N; Lakdawala, Ami S; Snyder, James P; Oliver, Warren V; Robertson, Tom A; Appleton, Trevor G; Fairlie, David P

    2004-04-21

    Alpha-Helices are key structural components of proteins and important recognition motifs in biology. Short peptides (peptide helices could be valuable for studying protein folding, modeling proteins, creating artificial proteins, and may aid the design of inhibitors or mimics of protein function. This study reports the facile incorporation of 3- and 4-alpha turns in 10-15 residue peptides through formation in situ of multiple cyclic metallopeptide modules [Pd(en)(H*XXXH*)](2+). The nonhelical peptides Ac-H*ELTH*H*VTDH*-NH(2) (1), Ac-H*ELTH*AVTDYH*ELTH*-NH(2) (2), and Ac-H*AAAH*HELTH*H*VTDH*-NH(2) (3) (H is histidine-methylated at imidazole-N3) react in N,N-dimethylformamide (DMF) or water with 2, 2, and 3 molar equivalents, respectively, of [Pd(en)(NO(3))(2)] to form exclusively [Pd(2)(en)(2)(Ac-H*ELTH*H*VTDH*-NH(2))](4+) (4), [Pd(2)(en)(2)(Ac-H*ELTH*AVTDYH*ELTH*-NH(2))](4+) (5), and [Pd(3)(en)(3)(Ac-H*AAAH*HELTH*H*VTDH*-NH(2))](6+) (6), characterized by mass spectrometry, 1D and 2D (1)H- and 1D (15)N-NMR spectroscopy. Despite the presence of multiple histidines and other possible metal-binding residues in these peptides, 2D (1)H NMR spectra reveal that Pd(en)(2+) is remarkably specific in coordinating to imidazole-N1 of only (i, i + 4) pairs of histidines (i.e., only those separated by three amino acids), resulting in 4-6 made up of cyclic metallopentapeptide modules ([Pd(en)(H*XXXH*)](2+))(n), n = 2, 2, 3, respectively, each cycle being a 22-membered ring. We have previously shown that a single metallopentapeptide can nucleate alpha-helicity (Kelso et al., Angew. Chem., Int. Ed. 2003, 42, 421-424.). We now demonstrate its use as an alpha-turn-mimicking module for the facile conversion of unstructured short peptides into helices of macrocycles and provide 1D and 2D NMR spectroscopic data, structure

  5. A RHAMM Mimetic Peptide Blocks Hyaluronan Signaling and Reduces Inflammation and Fibrogenesis in Excisional Skin Wounds

    PubMed Central

    Tolg, Cornelia; Hamilton, Sara R.; Zalinska, Ewa; McCulloch, Lori; Amin, Ripal; Akentieva, Natalia; Winnik, Francoise; Savani, Rashmin; Bagli, Darius J.; Luyt, Len G.; Cowman, Mary K.; McCarthy, Jim B.; Turley, Eva A.

    2013-01-01

    Hyaluronan is activated by fragmentation and controls inflammation and fibroplasia during wound repair and diseases (eg, cancer). Hyaluronan-binding peptides were identified that modify fibrogenesis during skin wound repair. Peptides were selected from 7- to 15mer phage display libraries by panning with hyaluronan-Sepharose beads and assayed for their ability to block fibroblast migration in response to hyaluronan oligosaccharides (10 kDa). A 15mer peptide (P15-1), with homology to receptor for hyaluronan mediated motility (RHAMM) hyaluronan binding sequences, was the most effective inhibitor. P15-1 bound to 10-kDa hyaluronan with an affinity of Kd = 10−7 and appeared to specifically mimic RHAMM since it significantly reduced binding of hyaluronan oligosaccharides to recombinant RHAMM but not to recombinant CD44 or TLR2,4, and altered wound repair in wild-type but not RHAMM−/− mice. One topical application of P15-1 to full-thickness excisional rat wounds significantly reduced wound macrophage number, fibroblast number, and blood vessel density compared to scrambled, negative control peptides. Wound collagen 1, transforming growth factor β-1, and α-smooth muscle actin were reduced, whereas tenascin C was increased, suggesting that P15-1 promoted a form of scarless healing. Signaling/microarray analyses showed that P15-1 blocks RHAMM-regulated focal adhesion kinase pathways in fibroblasts. These results identify a new class of reagents that attenuate proinflammatory, fibrotic repair by blocking hyaluronan oligosaccharide signaling. PMID:22889846

  6. Design of a RANK-Mimetic Peptide Inhibitor of Osteoclastogenesis with Enhanced RANKL-Binding Affinity

    PubMed Central

    Hur, Jeonghwan; Ghosh, Ambarnil; Kim, Kabsun; Ta, Hai Minh; Kim, Hyunju; Kim, Nacksung; Hwang, Hye-Yeon; Kim, Kyeong Kyu

    2016-01-01

    The receptor activator of nuclear factor κB (RANK) and its ligand RANKL are key regulators of osteoclastogenesis and well-recognized targets in developing treatments for bone disorders associated with excessive bone resorption, such as osteoporosis. Our previous work on the structure of the RANK-RANKL complex revealed that Loop3 of RANK, specifically the non-canonical disulfide bond at the tip, performs a crucial role in specific recognition of RANKL. It also demonstrated that peptide mimics of Loop3 were capable of interfering with the function of RANKL in osteoclastogenesis. Here, we reported the structure-based design of a smaller peptide with enhanced inhibitory efficiency. The kinetic analysis and osteoclast differentiation assay showed that in addition to the sharp turn induced by the disulfide bond, two consecutive arginine residues were also important for binding to RANKL and inhibiting osteoclastogenesis. Docking and molecular dynamics simulations proposed the binding mode of the peptide to the RANKL trimer, showing that the arginine residues provide electrostatic interactions with RANKL and contribute to stabilizing the complex. These findings provided useful information for the rational design of therapeutics for bone diseases associated with RANK/RANKL function. PMID:26923188

  7. The gamma interferon (IFN-gamma) mimetic peptide IFN-gamma (95-133) prevents encephalomyocarditis virus infection both in tissue culture and in mice.

    PubMed

    Mujtaba, Mustafa G; Patel, Chintak B; Patel, Ravi A; Flowers, Lawrence O; Burkhart, Marjorie A; Waiboci, Lilian W; Martin, James; Haider, Mohammad I; Ahmed, Chulbul M; Johnson, Howard M

    2006-08-01

    We have demonstrated previously that the C-terminal gamma interferon (IFN-gamma) mimetic peptide consisting of residues 95 to 133 [IFN-gamma(95-133)], which contains the crucial IFN-gamma nuclear localization sequence (NLS), has antiviral activity in tissue culture. Here we evaluate the efficacy of this peptide and its derivatives first in vitro and then in an animal model of lethal viral infection with the encephalomyocarditis (EMC) virus. Deletion of the NLS region from the IFN-gamma mimetic peptide IFN-gamma(95-133) resulted in loss of antiviral activity. However, the NLS region does not have antiviral activity in itself. Replacing the NLS region of IFN-gamma(95-133) with the NLS region of the simian virus 40 large T antigen retains the antiviral activity in tissue culture. IFN-gamma(95-133) prevented EMC virus-induced lethality in mice in a dose-dependent manner compared to controls. Mice treated with IFN-gamma(95-133) had no or low EMC virus titers in their internal organs, whereas control mice had consistently high viral titers, especially in the heart tissues. Injection of B8R protein, which is encoded by poxviruses as a defense mechanism to neutralize host IFN-gamma, did not inhibit IFN-gamma(95-133) protection against a lethal dose of EMC virus, whereas mice treated with rat IFN-gamma were not protected. The data presented here show that the IFN-gamma mimetic peptide IFN-gamma(95-133) prevents EMC virus infection in vivo and in vitro and may have potential against other lethal viruses, such as the smallpox virus, which encodes the B8R protein. PMID:16893996

  8. Peptide Mimetic of the S100A4 Protein Modulates Peripheral Nerve Regeneration and Attenuates the Progression of Neuropathy in Myelin Protein P0 Null Mice

    PubMed Central

    Moldovan, Mihai; Pinchenko, Volodymyr; Dmytriyeva, Oksana; Pankratova, Stanislava; Fugleholm, Kåre; Klingelhofer, Jorg; Bock, Elisabeth; Berezin, Vladimir; Krarup, Christian; Kiryushko, Darya

    2013-01-01

    We recently found that S100A4, a member of the multifunctional S100 protein family, protects neurons in the injured brain and identified two sequence motifs in S100A4 mediating its neurotrophic effect. Synthetic peptides encompassing these motifs stimulated neuritogenesis and survival in vitro and mimicked the S100A4-induced neuroprotection in brain trauma. Here, we investigated a possible function of S100A4 and its mimetics in the pathologies of the peripheral nervous system (PNS). We found that S100A4 was expressed in the injured PNS and that its peptide mimetic (H3) affected the regeneration and survival of myelinated axons. H3 accelerated electrophysiological, behavioral and morphological recovery after sciatic nerve crush while transiently delaying regeneration after sciatic nerve transection and repair. On the basis of the finding that both S100A4 and H3 increased neurite branching in vitro, these effects were attributed to the modulatory effect of H3 on initial axonal sprouting. In contrast to the modest effect of H3 on the time course of regeneration, H3 had a long-term neuroprotective effect in the myelin protein P0 null mice, a model of dysmyelinating neuropathy (Charcot-Marie-Tooth type 1 disease), where the peptide attenuated the deterioration of nerve conduction, demyelination and axonal loss. From these results, S100A4 mimetics emerge as a possible means to enhance axonal sprouting and survival, especially in the context of demyelinating neuropathies with secondary axonal loss, such as Charcot-Marie-Tooth type 1 disease. Moreover, our data suggest that S100A4 is a neuroprotectant in PNS and that other S100 proteins, sharing high homology in the H3 motif, may have important functions in PNS pathologies. PMID:23508572

  9. Label-free probe of HIV-1 TAT peptide binding to mimetic membranes.

    PubMed

    Rao, Yi; Kwok, Sheldon J J; Lombardi, Julien; Turro, Nicholas J; Eisenthal, Kenneth B

    2014-09-01

    The transacting activator of transduction (TAT) protein plays a key role in the progression of AIDS. Studies have shown that a +8 charged sequence of amino acids in the protein, called the TAT peptide, enables the TAT protein to penetrate cell membranes. To probe mechanisms of binding and translocation of the TAT peptide into the cell, investigators have used phospholipid liposomes as cell membrane mimics. We have used the method of surface potential sensitive second harmonic generation (SHG), which is a label-free and interface-selective method, to study the binding of TAT to anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-1'-rac-glycerol (POPG) and neutral 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes. It is the SHG sensitivity to the electrostatic field generated by a charged interface that enabled us to obtain the interfacial electrostatic potential. SHG together with the Poisson-Boltzmann equation yielded the dependence of the surface potential on the density of adsorbed TAT. We obtained the dissociation constants Kd for TAT binding to POPC and POPG liposomes and the maximum number of TATs that can bind to a given liposome surface. For POPC Kd was found to be 7.5 ± 2 μM, and for POPG Kd was 29.0 ± 4.0 μM. As TAT was added to the liposome solution the POPC surface potential changed from 0 mV to +37 mV, and for POPG it changed from -57 mV to -37 mV. A numerical calculation of Kd, which included all terms obtained from application of the Poisson-Boltzmann equation to the TAT liposome SHG data, was shown to be in good agreement with an approximated solution. PMID:25136100

  10. Label-free probe of HIV-1 TAT peptide binding to mimetic membranes

    PubMed Central

    Rao, Yi; Kwok, Sheldon J. J.; Lombardi, Julien; Turro, Nicholas J.; Eisenthal, Kenneth B.

    2014-01-01

    The transacting activator of transduction (TAT) protein plays a key role in the progression of AIDS. Studies have shown that a +8 charged sequence of amino acids in the protein, called the TAT peptide, enables the TAT protein to penetrate cell membranes. To probe mechanisms of binding and translocation of the TAT peptide into the cell, investigators have used phospholipid liposomes as cell membrane mimics. We have used the method of surface potential sensitive second harmonic generation (SHG), which is a label-free and interface-selective method, to study the binding of TAT to anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-1′-rac-glycerol (POPG) and neutral 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes. It is the SHG sensitivity to the electrostatic field generated by a charged interface that enabled us to obtain the interfacial electrostatic potential. SHG together with the Poisson–Boltzmann equation yielded the dependence of the surface potential on the density of adsorbed TAT. We obtained the dissociation constants Kd for TAT binding to POPC and POPG liposomes and the maximum number of TATs that can bind to a given liposome surface. For POPC Kd was found to be 7.5 ± 2 μM, and for POPG Kd was 29.0 ± 4.0 μM. As TAT was added to the liposome solution the POPC surface potential changed from 0 mV to +37 mV, and for POPG it changed from −57 mV to −37 mV. A numerical calculation of Kd, which included all terms obtained from application of the Poisson–Boltzmann equation to the TAT liposome SHG data, was shown to be in good agreement with an approximated solution. PMID:25136100

  11. The connexin43 mimetic peptide Gap19 inhibits hemichannels without altering gap junctional communication in astrocytes

    PubMed Central

    Abudara, Verónica; Bechberger, John; Freitas-Andrade, Moises; De Bock, Marijke; Wang, Nan; Bultynck, Geert; Naus, Christian C.; Leybaert, Luc; Giaume, Christian

    2014-01-01

    In the brain, astrocytes represent the cellular population that expresses the highest amount of connexins (Cxs). This family of membrane proteins is the molecular constituent of gap junction channels and hemichannels that provide pathways for direct cytoplasm-to-cytoplasm and inside-out exchange, respectively. Both types of Cx channels are permeable to ions and small signaling molecules allowing astrocytes to establish dynamic interactions with neurons. So far, most pharmacological approaches currently available do not distinguish between these two channel functions, stressing the need to develop new specific molecular tools. In astrocytes two major Cxs are expressed, Cx43 and Cx30, and there is now evidence indicating that at least Cx43 operates as a gap junction channel as well as a hemichannel in these cells. Based on studies in primary cultures as well as in acute hippocampal slices, we report here that Gap19, a nonapeptide derived from the cytoplasmic loop of Cx43, inhibits astroglial Cx43 hemichannels in a dose-dependent manner, without affecting gap junction channels. This peptide, which not only selectively inhibits hemichannels but is also specific for Cx43, can be delivered in vivo in mice as TAT-Gap19, and displays penetration into the brain parenchyma. As a result, Gap19 combined with other tools opens up new avenues to decipher the role of Cx43 hemichannels in interactions between astrocytes and neurons in physiological as well as pathological situations. PMID:25374505

  12. Self-assembled peptide amphiphile nanofibers and peg composite hydrogels as tunable ECM mimetic microenvironment.

    PubMed

    Goktas, Melis; Cinar, Goksu; Orujalipoor, Ilghar; Ide, Semra; Tekinay, Ayse B; Guler, Mustafa O

    2015-04-13

    Natural extracellular matrix (ECM) consists of complex signals interacting with each other to organize cellular behavior and responses. This sophisticated microenvironment can be mimicked by advanced materials presenting essential biochemical and physical properties in a synergistic manner. In this work, we developed a facile fabrication method for a novel nanofibrous self-assembled peptide amphiphile (PA) and poly(ethylene glycol) (PEG) composite hydrogel system with independently tunable biochemical, mechanical, and physical cues without any chemical modification of polymer backbone or additional polymer processing techniques to create synthetic ECM analogues. This approach allows noninteracting modification of multiple niche properties (e.g., bioactive ligands, stiffness, porosity), since no covalent conjugation method was used to modify PEG monomers for incorporation of bioactivity and porosity. Combining the self-assembled PA nanofibers with a chemically cross-linked polymer network simply by facile mixing followed by photopolymerization resulted in the formation of porous bioactive hydrogel systems. The resulting porous network can be functionalized with desired bioactive signaling epitopes by simply altering the amino acid sequence of the self-assembling PA molecule. In addition, the mechanical properties of the composite system can be precisely controlled by changing the PEG concentration. Therefore, nanofibrous self-assembled PA/PEG composite hydrogels reported in this work can provide new opportunities as versatile synthetic mimics of ECM with independently tunable biological and mechanical properties for tissue engineering and regenerative medicine applications. In addition, such systems could provide useful tools for investigation of how complex niche cues influence cellular behavior and tissue formation both in two-dimensional and three-dimensional platforms. PMID:25751623

  13. Creation of Apolipoprotein C-II (ApoC-II) Mutant Mice and Correction of Their Hypertriglyceridemia with an ApoC-II Mimetic Peptide.

    PubMed

    Sakurai, Toshihiro; Sakurai, Akiko; Vaisman, Boris L; Amar, Marcelo J; Liu, Chengyu; Gordon, Scott M; Drake, Steven K; Pryor, Milton; Sampson, Maureen L; Yang, Ling; Freeman, Lita A; Remaley, Alan T

    2016-02-01

    Apolipoprotein C-II (apoC-II) is a cofactor for lipoprotein lipase, a plasma enzyme that hydrolyzes triglycerides (TGs). ApoC-II deficiency in humans results in hypertriglyceridemia. We used zinc finger nucleases to create Apoc2 mutant mice to investigate the use of C-II-a, a short apoC-II mimetic peptide, as a therapy for apoC-II deficiency. Mutant mice produced a form of apoC-II with an uncleaved signal peptide that preferentially binds high-density lipoproteins (HDLs) due to a 3-amino acid deletion at the signal peptide cleavage site. Homozygous Apoc2 mutant mice had increased plasma TG (757.5 ± 281.2 mg/dl) and low HDL cholesterol (31.4 ± 14.7 mg/dl) compared with wild-type mice (TG, 55.9 ± 13.3 mg/dl; HDL cholesterol, 55.9 ± 14.3 mg/dl). TGs were found in light (density < 1.063 g/ml) lipoproteins in the size range of very-low-density lipoprotein and chylomicron remnants (40-200 nm). Intravenous injection of C-II-a (0.2, 1, and 5 μmol/kg) reduced plasma TG in a dose-dependent manner, with a maximum decrease of 90% occurring 30 minutes after the high dose. Plasma TG did not return to baseline until 48 hours later. Similar results were found with subcutaneous or intramuscular injections. Plasma half-life of C-II-a is 1.33 ± 0.72 hours, indicating that C-II-a only acutely activates lipolysis, and the sustained TG reduction is due to the relatively slow rate of new TG-rich lipoprotein synthesis. In summary, we describe a novel mouse model of apoC-II deficiency and show that an apoC-II mimetic peptide can reverse the hypertriglyceridemia in these mice, and thus could be a potential new therapy for apoC-II deficiency. PMID:26574515

  14. Creation of Apolipoprotein C-II (ApoC-II) Mutant Mice and Correction of Their Hypertriglyceridemia with an ApoC-II Mimetic Peptide

    PubMed Central

    Sakurai, Toshihiro; Sakurai, Akiko; Vaisman, Boris L.; Amar, Marcelo J.; Liu, Chengyu; Gordon, Scott M.; Drake, Steven K.; Pryor, Milton; Sampson, Maureen L.; Yang, Ling; Freeman, Lita A.

    2016-01-01

    Apolipoprotein C-II (apoC-II) is a cofactor for lipoprotein lipase, a plasma enzyme that hydrolyzes triglycerides (TGs). ApoC-II deficiency in humans results in hypertriglyceridemia. We used zinc finger nucleases to create Apoc2 mutant mice to investigate the use of C-II-a, a short apoC-II mimetic peptide, as a therapy for apoC-II deficiency. Mutant mice produced a form of apoC-II with an uncleaved signal peptide that preferentially binds high-density lipoproteins (HDLs) due to a 3-amino acid deletion at the signal peptide cleavage site. Homozygous Apoc2 mutant mice had increased plasma TG (757.5 ± 281.2 mg/dl) and low HDL cholesterol (31.4 ± 14.7 mg/dl) compared with wild-type mice (TG, 55.9 ± 13.3 mg/dl; HDL cholesterol, 55.9 ± 14.3 mg/dl). TGs were found in light (density < 1.063 g/ml) lipoproteins in the size range of very-low-density lipoprotein and chylomicron remnants (40–200 nm). Intravenous injection of C-II-a (0.2, 1, and 5 μmol/kg) reduced plasma TG in a dose-dependent manner, with a maximum decrease of 90% occurring 30 minutes after the high dose. Plasma TG did not return to baseline until 48 hours later. Similar results were found with subcutaneous or intramuscular injections. Plasma half-life of C-II-a is 1.33 ± 0.72 hours, indicating that C-II-a only acutely activates lipolysis, and the sustained TG reduction is due to the relatively slow rate of new TG-rich lipoprotein synthesis. In summary, we describe a novel mouse model of apoC-II deficiency and show that an apoC-II mimetic peptide can reverse the hypertriglyceridemia in these mice, and thus could be a potential new therapy for apoC-II deficiency. PMID:26574515

  15. Synthesis of two peptide mimetics as markers for chemical changes of wool's keratin during skin unhairing process.

    PubMed

    Danalev, Dantcho; Koleva, Margarita; Ivanova, Dimitrina; Vezenkov, Lyubomir; Vassilev, Nikolay

    2008-01-01

    The sheep skins unhairing process with preliminary alkaline treatment of the wool leads to two unnatural dipeptide mimetics lysinoalanine (Lys(*) - Ala) and ornithinoalanine (Orn(*)- Ala) obtaining. They are result from the keratin hydrolysis process. The changes of wool keratin make it resistant to sulphide degradation. We synthesized and characterized these unnatural dipeptides under the experimental conditions. The structures and mechanism of Lys(*) - Ala and Orn(*)- Ala obtaining were elucidated. The using of newly synthesized products as markers for control of wool's keratin changes during skin unhairing process was demonstrated. The developments have also been the result of economic and environmental pressures to meet environmental regulations. PMID:18473946

  16. Multi-Hierarchical Self-Assembly of Collagen Mimetic Peptides into AAB Type Heterotrimers, Nanofibers and Hydrogels Driven by Charged Pair Interactions

    NASA Astrophysics Data System (ADS)

    O'Leary, Lesley Russell

    2011-12-01

    Replicating the multi-hierarchical self-assembly of collagen (peptide chain to triple helix to nanofiber and, finally, to a hydrogel) has long attracted scientists, both from the fundamental science perspective of supramolecular chemistry and for the potential biomedical applications perceived in tissue engineering. In terms of triple helical formation, collagen is the most abundant protein in the human body with at least 28 types, yet research involving collagen mimetic systems has only recently began to consider the innate ability of collagen to control helix composition and register. Collagen triple helices can be homotrimeric or heterotrimeric and while some types of natural collagen form only one specific composition of helix, others can form multiple. It is critical to fully understand and, if possible, reproduce the control that native collagen has on helix composition and register. In terms of nanofiber formation, many approaches to drive the self-assembly of synthetic systems through the same steps as natural collagen have been partially successful, but none have simultaneously demonstrated all levels of structural assembly. In this work, advancements in the ability to control helix composition and replicate the multi-hierarchical assembly of collagen are described. Both positive and negative design for the assembly of AAB type collagen heterotrimers were utilized by promoting heterotrimer formation though the use of charged amino acids to form intra-helix electrostatic interactions, while simultaneously discouraging homotrimers, resulting in the identification of multiple peptide systems with full control over the composition of the resulting triple helix. Similar salt-bridged hydrogen bonds between charged residues were incorporated into nanofiber forming peptides, one of which successfully assembled into sticky-ended triple helices, nanofibers with characteristic triple helical packing visible in the solution state, and strong hydrogels that are

  17. DevR (DosR) mimetic peptides impair transcriptional regulation and survival of Mycobacterium tuberculosis under hypoxia by inhibiting the autokinase activity of DevS sensor kinase

    PubMed Central

    2014-01-01

    Background Two-component systems have emerged as compelling targets for antibacterial drug design for a number of reasons including the distinct histidine phosphorylation property of their constituent sensor kinases. The DevR-DevS/DosT two component system of Mycobacterium tuberculosis (M. tb) is essential for survival under hypoxia, a stress associated with dormancy development in vivo. In the present study a combinatorial peptide phage display library was screened for DevS histidine kinase interacting peptides with the aim of isolating inhibitors of DevR-DevS signaling. Results DevS binding peptides were identified from a phage display library after three rounds of panning using DevS as bait. The peptides showed sequence similarity with conserved residues in the N-terminal domain of DevR and suggested that they may represent interacting surfaces between DevS and DevR. Two DevR mimetic peptides were found to specifically inhibit DevR-dependent transcriptional activity and restrict the hypoxic survival of M. tb. The mechanism of peptide action is majorly attributed to an inhibition of DevS autokinase activity. Conclusions These findings demonstrate that DevR mimetic peptides impede DevS activation and that intercepting DevS activation at an early step in the signaling cascade impairs M. tb survival in a hypoxia persistence model. PMID:25048654

  18. Topical administration of a suppressor of cytokine signaling-1 (SOCS1) mimetic peptide inhibits ocular inflammation and mitigates ocular pathology during mouse uveitis.

    PubMed

    He, Chang; Yu, Cheng-Rong; Sun, Lin; Mahdi, Rashid M; Larkin, Joseph; Egwuagu, Charles E

    2015-08-01

    Uveitis is a diverse group of potentially sight-threatening intraocular inflammatory diseases and pathology derives from sustained production of pro-inflammatory cytokines in the optical axis. Although topical or systemic steroids are effective therapies, their adverse effects preclude prolonged usage and are impetus for seeking alternative immunosuppressive agents, particularly for patients with refractory uveitis. In this study, we synthesized a 16 amino acid membrane-penetrating lipophilic suppressor of cytokine signaling 1 peptide (SOCS1-KIR) that inhibits JAK/STAT signaling pathways and show that it suppresses and ameliorates experimental autoimmune uveitis (EAU), the mouse model of human uveitis. Fundus images, histological and optical coherence tomography analysis of eyes showed significant suppression of clinical disease, with average clinical score of 0.5 compared to 2.0 observed in control mice treated with scrambled peptide. We further show that SOCS1-KIR conferred protection from ocular pathology by inhibiting the expansion of pathogenic Th17 cells and inhibiting trafficking of inflammatory cells into the neuroretina during EAU. Dark-adapted scotopic and photopic electroretinograms further reveal that SOCS1-KIR prevented decrement of retinal function, underscoring potential neuroprotective effects of SOCS1-KIR in uveitis. Importantly, SOCS1-KIR is non-toxic, suggesting that topical administration of SOCS1-Mimetics can be exploited as a non-invasive treatment for uveitis and for limiting cytokine-mediated pathology in other ocular inflammatory diseases including scleritis. PMID:26094775

  19. On the substrate specificity of bacterial DD-peptidases: evidence from two series of peptidoglycan-mimetic peptides.

    PubMed Central

    Anderson, John W; Adediran, Suara A; Charlier, Paulette; Nguyen-Distèche, Martine; Frère, Jean-Marie; Nicholas, Robert A; Pratt, Rex F

    2003-01-01

    The reactions between bacterial DD-peptidases and beta-lactam antibiotics have been studied for many years. Less well understood are the interactions between these enzymes and their natural substrates, presumably the peptide moieties of peptidoglycan. In general, remarkably little activity has previously been demonstrated in vitro against potential peptide substrates, although in many cases the peptides employed were non-specific and not homologous with the relevant peptidoglycan. In this paper, the specificity of a panel of DD-peptidases against elements of species-specific D-alanyl-D-alanine peptides has been assessed. In two cases, those of soluble, low-molecular-mass DD-peptidases, high activity against the relevant peptides has been demonstrated. In these cases, the high specificity is towards the free N-terminus of the peptidoglycan fragment. With a number of other enzymes, particularly high-molecular-mass DD-peptidases, little or no activity against these peptides was observed. In separate experiments, the reactivity of the enzymes against the central, largely invariant, peptide stem was examined. None of the enzymes surveyed showed high activity against this structural element although weak specificity in the expected direction towards the one structural variable (D-gammaGln versus D-gammaGlu) was observed. The current state of understanding of the activity of these enzymes in vitro is discussed. PMID:12723972

  20. Comparing Variable-Length Polyglutamate Domains to Anchor an Osteoinductive Collagen-Mimetic Peptide to Diverse Bone Grafting Materials

    PubMed Central

    Bain, Jennifer L.; Culpepper, Bonnie K.; Reddy, Michael S.; Bellis, Susan L.

    2015-01-01

    Purpose Allografts, xenografts, and alloplasts are commonly used in craniofacial medicine as alternatives to autogenous bone grafts; however, these materials lack important bone-inducing proteins. A method for enhancing the osteoinductive potential of these commercially available materials would provide a major clinical advance. In this study, a calcium-binding domain, polyglutamate, was added to an osteoinductive peptide derived from collagen type I, Asp-Gly-Glu-Ala (DGEA), to anchor the peptide onto four different materials: freeze-dried bone allograft (FDBA); anorganic bovine bone (ABB); β-tricalcium phosphate (β-TCP); and a calcium sulfate bone cement (CaSO4). The authors also examined whether peptide binding and retention could be tuned by altering the number of glutamate residues within the polyglutamate domain. Materials and Methods DGEA or DGEA modified with diglutamate (E2DGEA), tetraglutamate (E4DGEA), or heptaglutamate (E7DGEA) were evaluated for binding and release to the grafting materials. Peptides were conjugated with a fluorescein isothiocyanate (FITC) tag to allow monitoring by fluorescent microscopy or through measurements of solution fluorescence. In vivo retention was evaluated by implanting graft materials coated with FITC-peptides into rat subcutaneous pouches. Results Significantly more peptide was loaded onto the four graft materials as the number of glutamates increased, with E7DGEA exhibiting the greatest binding. There was also significantly greater retention of peptides with longer glutamate domains following a 3-day incubation with agitation. Importantly, E7DGEA peptides remained on the grafts after a 2-month implantation into skin pouches, a sufficient interval to influence bony healing. Conclusion Variable-length polyglutamate domains can be added to osteoinductive peptides to control the amount of peptide bound and rate of peptide released. The lack of methods for tunable coupling of biologics to commercial graft sources has been a

  1. Molecular dynamics simulations of an apoliprotein A I derived peptide in explicit water

    NASA Astrophysics Data System (ADS)

    Stavrakoudis, Athanassios

    2008-08-01

    Molecular dynamics simulations have been performed for the 104-117 α-helical fragment of apoliprotein A-I using the CHARMM22 force field and the N AMD simulation engine. Simulation (50 ns in explicit water) resulted in significant appearance of π-helix conformation, which was totally diminished when the CMAP correction of the CHARMM force field was applied. This is consistent with other similar studies which suggest that the observation of π-helix in peptide conformation was force field biased rather actually existed. This study suggests that the 104-117 fragment of apoliprotein A-I has a stable α-helical conformation in water.

  2. Mimetic Attractors

    NASA Astrophysics Data System (ADS)

    Raza, Muhammad; Myrzakulov, Kairat; Momeni, Davood; Myrzakulov, Ratbay

    2016-05-01

    In this paper,we investigate the mathematical modeling for the cosmological attractors propagated in mimetic gravity upon which an interacting dark energy-dark matter is supposed to be existed. The average value of the interaction of these percentages, namely Γ i say, may be used to investigate generally the modeling of an attractor; the actual value could only be determined by data in any particular case. We have seen, for example, that it was led to investigate the subject of initially invariant submanifolds.

  3. A Peptide Mimetic of 5-Acetylneuraminic Acid-Galactose Binds with High Avidity to Siglecs and NKG2D

    PubMed Central

    Eggink, Laura L.; Spyroulias, Georgios A.; Jones, Norman G.; Hanson, Carl V.; Hoober, J. Kenneth

    2015-01-01

    We previously identified several peptide sequences that mimicked the terminal sugars of complex glycans. Using plant lectins as analogs of lectin-type cell-surface receptors, a tetravalent form of a peptide with the sequence NPSHPLSG, designated svH1C, bound with high avidity to lectins specific for glycans with terminal 5-acetylneuraminic acid (Neu5Ac)-galactose (Gal)/N-acetylgalactosamine (GalNAc) sequences. In this report, we show by circular dichroism and NMR spectra that svH1C lacks an ordered structure and thus interacts with binding sites from a flexible conformation. The peptide binds with high avidity to several recombinant human siglec receptors that bind preferentially to Neu5Ac(α2,3)Gal, Neu5Ac(α2,6)GalNAc or Neu5Ac(α2,8)Neu5Ac ligands. In addition, the peptide bound the receptor NKG2D, which contains a lectin-like domain that binds Neu5Ac(α2,3)Gal. The peptide bound to these receptors with a KD in the range of 0.6 to 1 μM. Binding to these receptors was inhibited by the glycoprotein fetuin, which contains multiple glycans that terminate in Neu5Ac(α2,3)Gal or Neu5Ac(α2,6)Gal, and by sialyllactose. Binding of svH1C was not detected with CLEC9a, CLEC10a or DC-SIGN, which are lectin-type receptors specific for other sugars. Incubation of neuraminidase-treated human peripheral blood mononuclear cells with svH1C resulted in binding of the peptide to a subset of the CD14+ monocyte population. Tyrosine phosphorylation of siglecs decreased dramatically when peripheral blood mononuclear cells were treated with 100 nM svH1C. Subcutaneous, alternate-day injections of svH1C into mice induced several-fold increases in populations of several types of immune cells in the peritoneal cavity. These results support the conclusion that svH1C mimics Neu5Ac-containing sequences and interacts with cell-surface receptors with avidities sufficient to induce biological responses at low concentrations. The attenuation of inhibitory receptors suggests that svH1C has

  4. Inhibition of p53-dependent transcription by BOX-I phospho-peptide mimetics that bind to p300

    PubMed Central

    Dornan, David; Hupp, Ted R.

    2001-01-01

    The N-terminal BOX-I domain of p53 containing a docking site for the negative regulator MDM2 and the positive effector p300, harbours two recently identified phosphorylation sites at Thr18 or Ser20 whose affect on p300 is undefined. Biochemical assays demonstrate that although MDM2 binding is inhibited by these phosphorylations, p300 binding is strikingly stabilized by Thr18 or Ser20 phosphorylation. Introducing EGFP-BOX-I domain peptides with an aspartate substitution at Thr18 or Ser20 induced a significant inhibition of endogenous p53-dependent transcription in cycling cells, in irradiated cells, as well as in cells transiently co-transfected with p300 and p53. In contrast an EGFP-wild-type BOX-I domain peptide stimulated p53 activity via inhibition of MDM2 protein binding. These results suggest that phosphorylation of p53 at Thr18 or Ser20 can activate p53 by stabilizing the p300–p53 complex and also identify a class of small molecular weight ligands capable of selective discrimination between MDM2- and p300-dependent activities. PMID:11258706

  5. Inhibition of p53-dependent transcription by BOX-I phospho-peptide mimetics that bind to p300.

    PubMed

    Dornan, D; Hupp, T R

    2001-02-01

    The N-terminal BOX-I domain of p53 containing a docking site for the negative regulator MDM2 and the positive effector p300, harbours two recently identified phosphorylation sites at Thr18 or Ser20O whose affect on p300 is undefined. Biochemical assays demonstrate that although MDM2 binding is inhibited by these phosphorylations, p300 binding is strikingly stabilized by Thr18 or Ser20 phosphorylation. Introducing EGFP-BOX-I domain peptides with an aspartate substitution at Thr18 or Ser20 induced a significant inhibition of endogenous p53-dependent transcription in cycling cells, in irradiated cells, as well as in cells transiently co-transfected with p300 and p53. In contrast an EGFP-wild-type BOX-I domain peptide stimulated p53 activity via inhibition of MDM2 protein binding. These results suggest that phosphorylation of p53 at Thr18 or Ser20 can activate p53 by stabilizing the p300-p53 complex and also identify a class of small molecular weight ligands capable of selective discrimination between MDM2- and p300-dependent activities. PMID:11258706

  6. Mapping the Interaction of B Cell Leukemia 3 (BCL-3) and Nuclear Factor κB (NF-κB) p50 Identifies a BCL-3-mimetic Anti-inflammatory Peptide*

    PubMed Central

    Collins, Patricia E.; Grassia, Gianluca; Colleran, Amy; Kiely, Patrick A.; Ialenti, Armando; Maffia, Pasquale; Carmody, Ruaidhrí J.

    2015-01-01

    The NF-κB transcriptional response is tightly regulated by a number of processes including the phosphorylation, ubiquitination, and subsequent proteasomal degradation of NF-κB subunits. The IκB family protein BCL-3 stabilizes a NF-κB p50 homodimer·DNA complex through inhibition of p50 ubiquitination. This complex inhibits the binding of the transcriptionally active NF-κB subunits p65 and c-Rel on the promoters of NF-κB target genes and functions to suppress inflammatory gene expression. We have previously shown that the direct interaction between p50 and BCL-3 is required for BCL-3-mediated inhibition of pro-inflammatory gene expression. In this study we have used immobilized peptide array technology to define regions of BCl-3 that mediate interaction with p50 homodimers. Our data show that BCL-3 makes extensive contacts with p50 homodimers and in particular with ankyrin repeats (ANK) 1, 6, and 7, and the N-terminal region of Bcl-3. Using these data we have designed a BCL-3 mimetic peptide based on a region of the ANK1 of BCL-3 that interacts with p50 and shares low sequence similarity with other IκB proteins. When fused to a cargo carrying peptide sequence this BCL-3-derived peptide, but not a mutated peptide, inhibited Toll-like receptor-induced cytokine expression in vitro. The BCL-3 mimetic peptide was also effective in preventing inflammation in vivo in the carrageenan-induced paw edema mouse model. This study demonstrates that therapeutic strategies aimed at mimicking the functional activity of BCL-3 may be effective in the treatment of inflammatory disease. PMID:25922067

  7. Preclinical pharmacology, ocular tolerability and ocular hypotensive efficacy of a novel non-peptide bradykinin mimetic small molecule.

    PubMed

    Sharif, Najam A; Li, Linya; Katoli, Parvaneh; Xu, Shouxi; Veltman, James; Li, Byron; Scott, Daniel; Wax, Martin; Gallar, Juana; Acosta, Carmen; Belmonte, Carlos

    2014-11-01

    We sought to characterize the ocular pharmacology, tolerability and intraocular pressure (IOP)-lowering efficacy of FR-190997, a non-peptidic bradykinin (BK) B2-receptor agonist. FR-190997 possessed a relatively high receptor binding affinity (Ki = 27 nM) and a high in vitro potency (EC50 = 18.3 ± 4.4 nM) for inositol-1-phosphate generation via human cloned B2-receptors expressed in host cells with mimimal activity at B1-receptors. It also mobilized intracellular Ca2+ in isolated human trabecular meshwork (h-TM), ciliary muscle (h-CM), and in immortalized non-pigmented ciliary epithelial (h-iNPE) cells (EC50s = 167-384 nM; Emax = 32-86% of BK-induced response). HOE-140, a selective B2-receptor antagonist, potently blocked the latter effects of FR-190997 (e.g., IC50 = 7.3 ± 0.6 nM in h-CM cells). FR-190997 also stimulated the release of prostaglandins (PGs) from h-TM and h-CM cells (EC50s = 60-84 nM; Emax = 29-44% relative to max. BK-induced effects). FR-190997 (0.3-300 μg t.o.) did not activate cat corneal polymodal nociceptors and did not cause ocular discomfort in Dutch-Belted rabbits, but it was not well tolerated in New Zealand albino rabbits and Hartley guinea pigs. A single topical ocular (t.o.) dose of 1% FR-190997 in Dutch-Belted rabbits and mixed breed cats did not lower IOP. However, FR-190997 efficaciously lowered IOP of conscious ocular hypertensive cynomolgus monkey eyes (e.g., 34.5 ± 7.5% decrease; 6 h post-dose of 30 μg t.o.; n = 8). Thus, FR-190997 is an unexampled efficacious ocular hypotensive B2-receptor non-peptide BK agonist that activates multiple signaling pathways to cause IOP reduction. PMID:25307520

  8. The AF4-mimetic peptide, PFWT, induces necrotic cell death in MV4-11 leukemia cells

    PubMed Central

    Palermo, Christine M.; Bennett, Cecily A.; Winters, Amanda C.; Hemenway, Charles S.

    2008-01-01

    Despite ongoing success in the treatment of childhood acute lymphoblastic leukemia, patients harboring translocations involving the MLL gene at chromosome 11q23 remain resistant to treatment. To improve outcomes, novel therapeutics designed to target the unusual biology of these leukemias need to be developed. Previously, we identified an interaction between the two most common MLL fusion proteins, AF4 and AF9, and designed a synthetic peptide (PFWT) capable of disrupting this interaction. PFWT induced cell death in leukemia cells expressing MLL-AF4 with little effect on the colony forming potential of hematopoietic progenitor cells, suggesting the AF4–AF9 complex is an important pharmacological target for leukemia therapy and PFWT is a promising chemotherapeutic prototype. In these studies, we demonstrate that PFWT induces death by necrosis in MV4-11 cells. Cell death is characterized by rapid loss of plasma membrane integrity with maintenance of nuclear membrane integrity, and is independent of caspase activation, DNA fragmentation, and mitochondrial membrane depolarization. PFWT-mediated necrosis is inhibited by the serine protease inhibitor TLCK, suggesting this death pathway is regulated. Given the resistance of t(4;11) leukemias to conventional chemotherapeutic agents that induce apoptosis, further identification of the molecular events mediating this death process should uncover new avenues for therapeutic intervention. PMID:17875318

  9. Post-training intrahippocampal injection of synthetic poly-α-2,8-sialic acid-neural cell adhesion molecule mimetic peptide improves spatial long-term performance in mice

    PubMed Central

    Florian, Cédrick; Foltz, Jane; Norreel, Jean-Chrétien; Rougon, Geneviève; Roullet, Pascal

    2006-01-01

    Several data have shown that the neural cell adhesion molecule (NCAM) is necessary for long-term memory formation and might play a role in the structural reorganization of synapses. The NCAM, encoded by a single gene, is represented by several isoforms that differ with regard to their content of α-2,8-linked sialic acid residues (PSA) on their extracellular domain. The carbohydrate PSA is known to promote plasticity, and PSA-NCAM isoforms remain expressed in the CA3 region of the adult hippocampus. In the present study, we investigated the effect on spatial memory consolidation of a PSA gain of function by injecting a PSA mimetic peptide (termed pr2) into the dorsal hippocampus. Mice were subjected to massed training in the spatial version of the water maze. Five hours after the last training session, experimental mice received an injection of pr2, whereas control mice received PBS or reverse peptide injections in the hippocampal CA3 region. Memory retention was tested at different time intervals: 24 h, 1 wk, and 4 wk. The results showed that the post-training infusion of pr2 peptide significantly increases spatial performance whenever it was assessed after the training phase. By contrast, administration of the control reverse peptide did not affect retention performance. These findings provide evidence that (1) PSA-NCAM is involved in memory consolidation processes in the CA3 hippocampal region, and (2) PSA mimetic peptides can facilitate the formation of long-term spatial memory when injected during the memory consolidation phase. PMID:16705136

  10. Development of the Fibronectin-Mimetic Peptide KSSPHSRN(SG)5RGDSP as a Novel Radioprobe for Molecular Imaging of the Cancer Biomarker α5β1 Integrin.

    PubMed

    Jin, Zhao-Hui; Furukawa, Takako; Kumata, Katsushi; Xie, Lin; Yui, Joji; Wakizaka, Hidekatsu; Fujibayashi, Yasuhisa; Zhang, Ming-Rong; Saga, Tsuneo

    2015-01-01

    α5β1 Integrin, a fibronectin receptor, is becoming a pertinent therapeutic target and a promising prognostic biomarker for cancer patients. The aim of this study was to functionalize an α5β1-specific fibronectin-mimetic peptide sequence KSSPHSRN(SG)5RGDSP (called PR_b) as a positron emission tomography (PET) probe. PR_b was modified by addition of a β-alanine residue, conjugated with 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA), and radiolabeled with (18)F based on the chelation of (18)F-aluminum fluoride. A control probe was produced by glycine to alanine substitution in the RGD motif of PR_b. Cell binding and blocking assays, autoradiographic evaluation of tissue binding and blocking, dynamic PET scans, and a biodistribution study were conducted using cell lines and murine tumor models with determined expression levels of α5β1 and other related integrins. (18)F-PR_b was produced with a labeling yield of 22.3±1.9% based on (18)F-F(-), a radiochemical purity of >99%, and a specific activity of 30-70 GBq/µmol; it exhibited α5β1-binding activity and specificity in vitro, ex vivo, and in vivo, and had a rapid blood clearance and a predominant renal excretion pathway. In vivo α5β1-positive tumors could be clearly visualized by (18)F-PR_b PET imaging. Both imaging and biodistribution studies suggested higher uptake of (18)F-PR_b in α5β1-positive tumors than in α5β1-negative tumors and higher α5β1-positive tumor uptake of (18)F-PR_b than the control probe. In contrast, there was no significant difference seen in the contralateral muscle uptake. A PET radioprobe, (18)F-PR_b, was developed de novo and potentially can be used for noninvasive detection of α5β1 expression in tumors. PMID:26277991

  11. Converting One-Face α-Helix Mimetics into Amphiphilic α-Helix Mimetics as Potent Inhibitors of Protein-Protein Interactions.

    PubMed

    Lee, Ji Hoon; Oh, Misook; Kim, Hyun Soo; Lee, Huisun; Im, Wonpil; Lim, Hyun-Suk

    2016-01-11

    Many biologically active α-helical peptides adopt amphiphilic helical structures that contain hydrophobic residues on one side and hydrophilic residues on the other side. Therefore, α-helix mimetics capable of mimicking such amphiphilic helical peptides should possess higher binding affinity and specificity to target proteins. Here we describe an efficient method for generating amphiphilic α-helix mimetics. One-face α-helix mimetics having hydrophobic side chains on one side was readily converted into amphiphilic α-helix mimetics by introducing appropriate charged residues on the opposite side. We also demonstrate that such two-face amphiphilic α-helix mimetics indeed show remarkably improved binding affinity to a target protein, compared to one-face hydrophobic α-helix mimetics. We believe that generating a large combinatorial library of these amphiphilic α-helix mimetics can be valuable for rapid discovery of highly potent and specific modulators of protein-protein interactions. PMID:26651509

  12. Cosmology with Mimetic Matter

    SciTech Connect

    Chamseddine, Ali H.; Mukhanov, Viatcheslav; Vikman, Alexander E-mail: viatcheslav.Mukhanov@lmu.de

    2014-06-01

    We consider minimal extensions of the recently proposed Mimetic Dark Matter and show that by introducing a potential for the mimetic non-dynamical scalar field we can mimic nearly any gravitational properties of the normal matter. In particular, the mimetic matter can provide us with inflaton, quintessence and even can lead to a bouncing nonsingular universe. We also investigate the behaviour of cosmological perturbations due to a mimetic matter. We demonstrate that simple mimetic inflation can produce red-tilted scalar perturbations which are largely enhanced over gravity waves.

  13. Anti-inflammatory and cholesterol-reducing properties of apolipoprotein mimetics: a review.

    PubMed

    White, C Roger; Garber, David W; Anantharamaiah, G M

    2014-10-01

    Reduced levels of HDL cholesterol (HDL-C) are a strong independent predictor of coronary artery disease (CAD) risk. The major anti-atherogenic function of HDL is to mediate reverse cholesterol transport. This response is highly dependent on apoA-I and apoE, protein components of HDL. Randomized clinical trials have assessed effects of several classes of drugs on plasma cholesterol levels in CAD patients. Agents including cholestyramine, fibrates, niacin, and statins significantly lower LDL cholesterol (LDL-C) and induce modest increases in HDL-C, but tolerance issues and undesirable side effects are common. Additionally, residual risk may be present in patients with persistently low HDL-C and other complications despite a reduction in LDL-C. These observations have fueled interest in the development of new pharmacotherapies that positively impact circulating lipoproteins. The goal of this review is to discuss the therapeutic potential of synthetic apolipoprotein mimetic peptides. These include apoA-I mimetic peptides that have undergone initial clinical assessment. We also discuss newer apoE mimetics that mediate the clearance of atherogenic lipids from the circulation and possess anti-inflammatory properties. One of these (AEM-28) has recently been given orphan drug status and is undergoing clinical trials. PMID:25157031

  14. Anti-inflammatory and cholesterol-reducing properties of apolipoprotein mimetics: a review

    PubMed Central

    White, C. Roger; Garber, David W.; Anantharamaiah, G. M.

    2014-01-01

    Reduced levels of HDL cholesterol (HDL-C) are a strong independent predictor of coronary artery disease (CAD) risk. The major anti-atherogenic function of HDL is to mediate reverse cholesterol transport. This response is highly dependent on apoA-I and apoE, protein components of HDL. Randomized clinical trials have assessed effects of several classes of drugs on plasma cholesterol levels in CAD patients. Agents including cholestyramine, fibrates, niacin, and statins significantly lower LDL cholesterol (LDL-C) and induce modest increases in HDL-C, but tolerance issues and undesirable side effects are common. Additionally, residual risk may be present in patients with persistently low HDL-C and other complications despite a reduction in LDL-C. These observations have fueled interest in the development of new pharmacotherapies that positively impact circulating lipoproteins. The goal of this review is to discuss the therapeutic potential of synthetic apolipoprotein mimetic peptides. These include apoA-I mimetic peptides that have undergone initial clinical assessment. We also discuss newer apoE mimetics that mediate the clearance of atherogenic lipids from the circulation and possess anti-inflammatory properties. One of these (AEM-28) has recently been given orphan drug status and is undergoing clinical trials. PMID:25157031

  15. A Placebo-Controlled Study on the Effects of the Glucagon-Like Peptide-1 Mimetic, Exenatide, on Insulin Secretion, Body Composition and Adipokines in Obese, Client-Owned Cats.

    PubMed

    Hoelmkjaer, Kirsten M; Wewer Albrechtsen, Nicolai J; Holst, Jens J; Cronin, Anna M; Nielsen, Dorte H; Mandrup-Poulsen, Thomas; Bjornvad, Charlotte R

    2016-01-01

    Glucagon-like Peptide-1 mimetics increase insulin secretion and reduces body weight in humans. In lean, healthy cats, short-term treatment has produced similar results, whereas the effect in obese cats or with extended duration of treatment is unknown. Here, prolonged (12 weeks) treatment with the Glucagon-like Peptide-1 mimetic, exenatide, was evaluated in 12 obese, but otherwise healthy, client-owned cats. Cats were randomized to exenatide (1.0 μg/kg) or placebo treatment twice daily for 12 weeks. The primary endpoint was changes in insulin concentration; the secondary endpoints were glucose homeostasis, body weight, body composition as measured by dual-energy x-ray absorptiometry and overall safety. An intravenous glucose tolerance test (1 g/kg body weight) was conducted at week 0 and week 12. Exenatide did not change the insulin concentration, plasma glucose concentration or glucose tolerance (P>0.05 for all). Exenatide tended to reduce body weight on continued normal feeding. Median relative weight loss after 12 weeks was 5.1% (range 1.7 to 8.4%) in the exenatide group versus 3.2% (range -5.3 to 5.7%) in the placebo group (P = 0.10). Body composition and adipokine levels were unaffected by exenatide (P>0.05). Twelve weeks of exenatide was well-tolerated, with only two cases of mild, self-limiting gastrointestinal signs and a single case of mild hypoglycemia. The long-term insulinotropic effect of exenatide appeared less pronounced in obese cats compared to previous short-term studies in lean cats. Further investigations are required to fully elucidate the effect on insulin secretion, glucose tolerance and body weight in obese cats. PMID:27136422

  16. A Placebo-Controlled Study on the Effects of the Glucagon-Like Peptide-1 Mimetic, Exenatide, on Insulin Secretion, Body Composition and Adipokines in Obese, Client-Owned Cats

    PubMed Central

    Hoelmkjaer, Kirsten M.; Wewer Albrechtsen, Nicolai J.; Holst, Jens J.; Cronin, Anna M.; Nielsen, Dorte H.; Mandrup-Poulsen, Thomas; Bjornvad, Charlotte R.

    2016-01-01

    Glucagon-like Peptide-1 mimetics increase insulin secretion and reduces body weight in humans. In lean, healthy cats, short-term treatment has produced similar results, whereas the effect in obese cats or with extended duration of treatment is unknown. Here, prolonged (12 weeks) treatment with the Glucagon-like Peptide-1 mimetic, exenatide, was evaluated in 12 obese, but otherwise healthy, client-owned cats. Cats were randomized to exenatide (1.0 μg/kg) or placebo treatment twice daily for 12 weeks. The primary endpoint was changes in insulin concentration; the secondary endpoints were glucose homeostasis, body weight, body composition as measured by dual-energy x-ray absorptiometry and overall safety. An intravenous glucose tolerance test (1 g/kg body weight) was conducted at week 0 and week 12. Exenatide did not change the insulin concentration, plasma glucose concentration or glucose tolerance (P>0.05 for all). Exenatide tended to reduce body weight on continued normal feeding. Median relative weight loss after 12 weeks was 5.1% (range 1.7 to 8.4%) in the exenatide group versus 3.2% (range -5.3 to 5.7%) in the placebo group (P = 0.10). Body composition and adipokine levels were unaffected by exenatide (P>0.05). Twelve weeks of exenatide was well-tolerated, with only two cases of mild, self-limiting gastrointestinal signs and a single case of mild hypoglycemia. The long-term insulinotropic effect of exenatide appeared less pronounced in obese cats compared to previous short-term studies in lean cats. Further investigations are required to fully elucidate the effect on insulin secretion, glucose tolerance and body weight in obese cats. PMID:27136422

  17. A synthetic heparan sulfate-mimetic peptide conjugated to a mini CD4 displays very high anti- HIV-1 activity independently of coreceptor usage.

    PubMed

    Connell, Bridgette Janine; Baleux, Françoise; Coic, Yves-Marie; Clayette, Pascal; Bonnaffé, David; Lortat-Jacob, Hugues

    2012-01-27

    The HIV-1 envelope gp120, which features both the virus receptor (CD4) and coreceptor (CCR5/CXCR4) binding sites, offers multiple sites for therapeutic intervention. However, the latter becomes exposed, thus vulnerable to inhibition, only transiently when the virus has already bound cellular CD4. To pierce this defense mechanism, we engineered a series of heparan sulfate mimicking tridecapeptides and showed that one of them target the gp120 coreceptor binding site with μM affinity. Covalently linked to a CD4-mimetic that binds to gp120 and renders the coreceptor binding domain available to be targeted, the conjugated tridecapeptide now displays nanomolar affinity for its target. Using solubilized coreceptors captured on top of sensorchip we show that it inhibits gp120 binding to both CCR5 and CXCR4 and in peripheral blood mononuclear cells broadly inhibits HIV-1 replication with an IC(50) of 1 nM. PMID:22284360

  18. Unimodular-mimetic cosmology

    NASA Astrophysics Data System (ADS)

    Nojiri, S.; Odintsov, S. D.; Oikonomou, V. K.

    2016-06-01

    We combine the unimodular gravity and mimetic gravity theories into a unified theoretical framework, which is proposed to provide a suggestive proposal for a framework that may assist in the discussion and search for a solution to the cosmological constant problem and the dark matter issue. After providing the formulation of the unimodular mimetic gravity and investigating all the new features that the vacuum unimodular gravity implies, by using the underlying reconstruction method, we realize some well known cosmological evolutions, with some of these being exotic for the ordinary Einstein–Hilbert gravity. Specifically we provide the vacuum unimodular mimetic gravity description of the de Sitter cosmology and of the perfect fluid with constant equation of state cosmology. As we demonstrate, these cosmologies can be realized by vacuum mimetic unimodular gravity, without the existence of any matter fluid source. Moreover, we investigate how cosmologically viable cosmologies, which are compatible with the recent observational data, can be realized by the vacuum unimodular mimetic gravity. Since in some cases, a graceful exit from inflation problem might exist, we provide a qualitative description of the mechanism that can potentially generate the graceful exit from inflation in these theories, by searching for the unstable de Sitter solutions in the context of unimodular mimetic theories of gravity.

  19. Molecules that Mimic Apolipoprotein A-I: Potential Agents for Treating Atherosclerosis

    PubMed Central

    Leman, Luke J.; Maryanoff, Bruce E.; Ghadiri, M. Reza

    2013-01-01

    Certain amphipathic α-helical peptides can functionally mimic many of the properties of full-length apolipoproteins, thereby offering an approach to modulate high-density lipoprotein (HDL) for combating atherosclerosis. In this Perspective, we summarize the key findings and advances over the past 25 years in the development of peptides that mimic apolipoproteins, especially apolipoprotein A-I (apoA-I). This assemblage of information provides a reasonably clear picture of the state of the art in the apolipoprotein mimetic field, an appreciation of the potential for such agents in pharmacotherapy, and a sense of the opportunities for optimizing the functional properties of HDL. PMID:24168751

  20. Structural Basis for Species Selectivity in the HIV-1 gp120-CD4 Interaction: Restoring Affinity to gp120 in Murine CD4 Mimetic Peptides

    PubMed Central

    Kassler, Kristin; Meier, Julia; Eichler, Jutta; Sticht, Heinrich

    2011-01-01

    The first step of HIV-1 infection involves interaction between the viral glycoprotein gp120 and the human cellular receptor CD4. Inhibition of the gp120-CD4 interaction represents an attractive strategy to block HIV-1 infection. In an attempt to explore the known lack of affinity of murine CD4 to gp120, we have investigated peptides presenting the putative gp120-binding site of murine CD4 (mCD4). Molecular modeling indicates that mCD4 protein cannot bind gp120 due to steric clashes, while the larger conformational flexibility of mCD4 peptides allows an interaction. This finding is confirmed by experimental binding assays, which also evidenced specificity of the peptide-gp120 interaction. Molecular dynamics simulations indicate that the mCD4-peptide stably interacts with gp120 via an intermolecular β-sheet, while an important salt-bridge formed by a C-terminal lysine is lost. Fixation of the C-terminus by introducing a disulfide bridge between the N- and C-termini of the peptide significantly enhanced the affinity to gp120. PMID:22312332

  1. Mimetic finite difference method

    NASA Astrophysics Data System (ADS)

    Lipnikov, Konstantin; Manzini, Gianmarco; Shashkov, Mikhail

    2014-01-01

    The mimetic finite difference (MFD) method mimics fundamental properties of mathematical and physical systems including conservation laws, symmetry and positivity of solutions, duality and self-adjointness of differential operators, and exact mathematical identities of the vector and tensor calculus. This article is the first comprehensive review of the 50-year long history of the mimetic methodology and describes in a systematic way the major mimetic ideas and their relevance to academic and real-life problems. The supporting applications include diffusion, electromagnetics, fluid flow, and Lagrangian hydrodynamics problems. The article provides enough details to build various discrete operators on unstructured polygonal and polyhedral meshes and summarizes the major convergence results for the mimetic approximations. Most of these theoretical results, which are presented here as lemmas, propositions and theorems, are either original or an extension of existing results to a more general formulation using polyhedral meshes. Finally, flexibility and extensibility of the mimetic methodology are shown by deriving higher-order approximations, enforcing discrete maximum principles for diffusion problems, and ensuring the numerical stability for saddle-point systems.

  2. Involvement of the Receptor for Formylated Peptides in the in Vivo Anti-Migratory Actions of Annexin 1 and its Mimetics

    PubMed Central

    Perretti, Mauro; Getting, Stephen J.; Solito, Egle; Murphy, Philip M.; Gao, Ji-Liang

    2001-01-01

    An innovative avenue for anti-inflammatory therapy is inhibition of neutrophil extravasation by potentiating the action of endogenous anti-inflammatory mediators. The glucocorticoid-inducible protein annexin 1 and derived peptides are effective in inhibiting neutrophil extravasation. Here we tested the hypothesis that an interaction with the receptor for formylated peptide (FPR), so far reported only in vitro, could be the mechanism for this in vivo action. In a model of mouse peritonitis, FPR antagonists abrogated the anti-migratory effects of peptides Ac2-26 and Ac2-12, with a partial reduction in annexin 1 effects. A similar result was obtained in FPR (knock-out) KO mice. Binding of annexin 1 to circulating leukocytes was reduced (>50%) in FPR KO mice. In vitro, annexin binding to peritoneal macrophages was also markedly reduced in FPR KO mice. Finally, evidence of direct annexin 1 binding to murine FPR was obtained with HEK-293 cells transfected with the receptor. Overall, these results indicate a functional role for FPR in the anti-migratory effect of annexin 1 and derived peptides. PMID:11395373

  3. Bacterial ClpB heat-shock protein, an antigen-mimetic of the anorexigenic peptide α-MSH, at the origin of eating disorders.

    PubMed

    Tennoune, N; Chan, P; Breton, J; Legrand, R; Chabane, Y N; Akkermann, K; Järv, A; Ouelaa, W; Takagi, K; Ghouzali, I; Francois, M; Lucas, N; Bole-Feysot, C; Pestel-Caron, M; do Rego, J-C; Vaudry, D; Harro, J; Dé, E; Déchelotte, P; Fetissov, S O

    2014-01-01

    The molecular mechanisms at the origin of eating disorders (EDs), including anorexia nervosa (AN), bulimia and binge-eating disorder (BED), are currently unknown. Previous data indicated that immunoglobulins (Igs) or autoantibodies (auto-Abs) reactive with α-melanocyte-stimulating hormone (α-MSH) are involved in regulation of feeding and emotion; however, the origin of such auto-Abs is unknown. Here, using proteomics, we identified ClpB heat-shock disaggregation chaperone protein of commensal gut bacteria Escherichia coli as a conformational antigen mimetic of α-MSH. We show that ClpB-immunized mice produce anti-ClpB IgG crossreactive with α-MSH, influencing food intake, body weight, anxiety and melanocortin receptor 4 signaling. Furthermore, chronic intragastric delivery of E. coli in mice decreased food intake and stimulated formation of ClpB- and α-MSH-reactive antibodies, while ClpB-deficient E. coli did not affect food intake or antibody levels. Finally, we show that plasma levels of anti-ClpB IgG crossreactive with α-MSH are increased in patients with AN, bulimia and BED, and that the ED Inventory-2 scores in ED patients correlate with anti-ClpB IgG and IgM, which is similar to our previous findings for α-MSH auto-Abs. In conclusion, this work shows that the bacterial ClpB protein, which is present in several commensal and pathogenic microorganisms, can be responsible for the production of auto-Abs crossreactive with α-MSH, associated with altered feeding and emotion in humans with ED. Our data suggest that ClpB-expressing gut microorganisms might be involved in the etiology of EDs. PMID:25290265

  4. Bacterial ClpB heat-shock protein, an antigen-mimetic of the anorexigenic peptide α-MSH, at the origin of eating disorders

    PubMed Central

    Tennoune, N; Chan, P; Breton, J; Legrand, R; Chabane, Y N; Akkermann, K; Järv, A; Ouelaa, W; Takagi, K; Ghouzali, I; Francois, M; Lucas, N; Bole-Feysot, C; Pestel-Caron, M; do Rego, J-C; Vaudry, D; Harro, J; Dé, E; Déchelotte, P; Fetissov, S O

    2014-01-01

    The molecular mechanisms at the origin of eating disorders (EDs), including anorexia nervosa (AN), bulimia and binge-eating disorder (BED), are currently unknown. Previous data indicated that immunoglobulins (Igs) or autoantibodies (auto-Abs) reactive with α-melanocyte-stimulating hormone (α-MSH) are involved in regulation of feeding and emotion; however, the origin of such auto-Abs is unknown. Here, using proteomics, we identified ClpB heat-shock disaggregation chaperone protein of commensal gut bacteria Escherichia coli as a conformational antigen mimetic of α-MSH. We show that ClpB-immunized mice produce anti-ClpB IgG crossreactive with α-MSH, influencing food intake, body weight, anxiety and melanocortin receptor 4 signaling. Furthermore, chronic intragastric delivery of E. coli in mice decreased food intake and stimulated formation of ClpB- and α-MSH-reactive antibodies, while ClpB-deficient E. coli did not affect food intake or antibody levels. Finally, we show that plasma levels of anti-ClpB IgG crossreactive with α-MSH are increased in patients with AN, bulimia and BED, and that the ED Inventory-2 scores in ED patients correlate with anti-ClpB IgG and IgM, which is similar to our previous findings for α-MSH auto-Abs. In conclusion, this work shows that the bacterial ClpB protein, which is present in several commensal and pathogenic microorganisms, can be responsible for the production of auto-Abs crossreactive with α-MSH, associated with altered feeding and emotion in humans with ED. Our data suggest that ClpB-expressing gut microorganisms might be involved in the etiology of EDs. PMID:25290265

  5. Are all regions of folded proteins that undergo ligand-dependent order-disorder transitions targets for allosteric peptide mimetics?†

    PubMed Central

    Fenton, Aron W.

    2013-01-01

    Although the classical view of how proteins function relied on well folded structures, it is now recognized that the function of many proteins is dependent on being intrinsically disordered. The primary consideration in this work is the intermediate group of proteins that are overall well folded, but which contain small regions that undergo order/disorder transitions. In particular, the current focus is on those order/disorder transitions that are energetically coupled to ligand binding. As exemplified by the case of human liver pyruvate kinase (hL-PYK), peptides that mimic the sequence of the order/disorder region can be used as allosteric regulators of the enzyme. Based on this example and others reported in the literature, we propose that a similar use of peptides that mimic protein regions that experience ligand-dependent order-disorder transitions can be a generalized initiation point for the development of allosteric drugs. PMID:23520021

  6. Therapeutic Applications of Incretin Mimetics for Metabolic Diseases: Preclinical Studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exenatide (exendin-4) is an incretin mimetic peptide that shares several glucoregulatory actions with the endogenous incretin GLP-1. In addition to its actions on glucose control, exenatide produces effects to reduce food intake and body weight in all species studied. GLP-1 and exenatide have also b...

  7. Application of Multianalyte Microphysiometry to Characterize Macrophage Metabolic Responses to Oxidized LDL and Effects of an ApoA-1 Mimetic

    PubMed Central

    Kimmel, Danielle W.; Dole, William P.; Cliffel, David E.

    2013-01-01

    Although the interaction of macrophages with oxidized low density liopoprotein (oxLDL) is critical to the pathogenesis of atherosclerosis, relatively little is known about their metabolic response to oxLDL. Our development of the multianalyte microphysiometer (MAMP) allows for simultaneous measurement of extracellular metabolic substrates and products in real-time. Here, we use the MAMP to study changes in the metabolic rates of RAW-264.7 cells undergoing respiratory burst in response to oxLDL. These studies indicate that short duration exposure of macrophages to oxLDL results in time-dependent increases in glucose and oxygen consumption and in lactate production and extracellular acidification rate. Since apolipoprotein A-I (apoA-I) and apoA-I mimetics prevent experimental atherosclerosis, we hypothesized that the metabolic response of the macrophage during respiratory burst can be modulated by apoA-I mimetics. We tested this hypothesis by examining the effects of the apoA-I peptide mimetic, L-4F, alone and complexed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) on the macrophage metabolic response to oxLDL. L-4F and the DMPC/L-4F complexes attenuated the macrophage respiratory burst in response to oxLDL. The MAMP provides a novel approach for studying macrophage ligand-receptor interactions and cellular metabolism and our results provide new insights into the metabolic effects of oxLDL and mechanism of action of apoA-I mimetics. PMID:23313489

  8. Bradykinin antagonists modified with dipeptide mimetic beta-turn inducers.

    PubMed

    Alcaro, Maria C; Vinci, Valerio; D'Ursi, Anna M; Scrima, Mario; Chelli, Mario; Giuliani, Sandro; Meini, Stefania; Di Giacomo, Marcello; Colombo, Lino; Papini, Anna Maria

    2006-05-01

    Bradykinin (BK) is involved in a wide variety of pathophysiological processes. Potent BK peptide antagonists can be developed introducing constrained unnatural amino acids, necessary to force the secondary structure of the molecule. In this paper, we report a structure-activity relationship study of two peptide analogues of the potent B2 antagonist HOE 140 by replacing the D-Tic-Oic dipeptide with conformationally constrained dipeptide mimetic beta-turn inducers. PMID:16504505

  9. Fc-fusion mimetics.

    PubMed

    Khalili, H; Khaw, P T; Brocchini, S

    2016-06-24

    The Fc-fusion mimetic RpR 2[combining low line] was prepared by disulfide bridging conjugation using PEG in the place of the Fc. RpR 2[combining low line] displayed higher affinity for VEGF than aflibercept. This is caused primarily by a slower dissociation rate, which can prolong a drug at its site of action. RpRs have considerable potential for development as stable, organ specific therapeutics. PMID:27127811

  10. Overexpression of apolipoprotein A-I fused to an anti-transforming growth factor beta peptide modulates the tumorigenicity and immunogenicity of mouse colon cancer cells.

    PubMed

    Medina-Echeverz, José; Vasquez, Marcos; Gomar, Celia; Ardaiz, Nuria; Berraondo, Pedro

    2015-06-01

    Transforming growth factor beta (TGF-β) promotes tumor growth, invasion and metastasis in established tumors. In this study, we analyzed the effect of overexpressing an anti-TGF-β peptide fused to apolipoprotein A-I (ApoA-I) as a scaffold molecule. We generated and characterized stable MC38 colon carcinoma clones expressing ApoA-I fused to the anti-TGF-β peptide P144 and ApoA-I as control cells. We evaluated in vitro the gene expression profile, cell cycle and anchorage-independent growth. The in vivo tumorigenic potential and immunogenicity were analyzed inoculating the MC38 clones into C57BL/6 mice, recombination-activating gene 1 knockout mice or mice deficient in NK cells either subcutaneously or intrasplenically to generate hepatic metastases. While overexpression of ApoA-I had no effect on the parameters analyzed, ApoA-I fused to P144 markedly diminished the tumorigenic capacity and metastatic potential of MC38 in vitro and in vivo, thus generating a highly immunogenic cell line. MC38 cells transfected with ApoA-I fused to P144 triggered memory T cell responses able to eliminate the parental cell line upon re-challenge. In summary, expression of ApoA-I fused to P144 is a novel strategy to modulate TGF-β in tumor cells. These results highlight the potential of TGF-β as a target in the development of new antitumor treatments. PMID:25795134

  11. HDL therapy for cardiovascular diseases: the road to HDL mimetics.

    PubMed

    White, C Roger; Datta, Geeta; Zhang, Zhenghao; Gupta, Himanshu; Garber, David W; Mishra, Vinod K; Palgunachari, Mayakonda N; Handattu, Shaila P; Chaddha, Manjula; Anantharamaiah, G M

    2008-10-01

    3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are currently the drug of choice for the clinical management of elevated low-density lipoprotein (LDL) cholesterol. Although statin treatment provides an overall improvement in outcomes, clinical trial data reveal a significant number of cardiac events despite reaching targeted LDL levels. A low serum high-density lipoprotein (HDL) cholesterol level is an independent predictor of cardiovascular risk. Accordingly, there has been interest in determining whether HDL elevation, in addition to LDL lowering, further reduces risk in patients with coronary artery disease. Several commonly prescribed lipid-lowering therapies modestly raise HDL, but their use may be limited by the development of adverse reactions. Emerging data suggest that HDL quality and function may also be significantly reduced by atherosclerosis and other inflammatory diseases. The goal of this review is to discuss the current status of HDL therapeutics, with emphasis on a novel class of agent, the apolipoprotein A-I mimetic peptides, which improve the functional properties of HDL cholesterol. PMID:18706282

  12. Cylindrical solutions in mimetic gravity

    NASA Astrophysics Data System (ADS)

    Momeni, Davood; Myrzakulov, Kairat; Myrzakulov, Ratbay; Raza, Muhammad

    2016-06-01

    This paper is devoted to investigate cylindrical solutions in mimetic gravity. The explicit forms of the metric of this theory, namely mimetic-Kasner (say) have been obtained. In this study we have noticed that the Kasner's family of exact solutions needs to be reconsidered under this type of modified gravity. A no-go theorem is proposed for the exact solutions in the presence of a cosmological constant.

  13. Mimetics of Hormetic Agents: Stress-Resistance Triggers

    PubMed Central

    Sonneborn, Joan Smith

    2010-01-01

    Mimetics of hormetic agents offer a novel approach to adjust dose to minimize the risk of toxic response, and maximize the benefit of induction of at least partial physiological conditioning. Nature selected and preserved those organisms and triggers that promote tolerance to stress. The induced tolerance can serve to resist that challenge and can repair previous age, disease, and trauma damage as well to provide a more youthful response to other stresses. The associated physiological conditioning may include youthful restoration of DNA repair, resistance to oxidizing pollutants, protein structure and function repair, improved immunity, tissue remodeling, adjustments in central and peripheral nervous systems, and altered metabolism. By elucidating common pathways activated by hormetic agent’s mimetics, new strategies for intervention in aging, disease, and trauma emerge. Intervention potential in cancer, diabetes, age-related diseases, infectious diseases, cardiovascular diseases, and Alzheimer’s disease are possible. Some hormetic mimetics exist in pathways in primitive organisms and are active or latent in humans. Peptides, oligonucleotides, and hormones are among the mimetics that activate latent resistance to radiation, physical endurance, strength, and immunity to physiological condition tolerance to stress. Co-activators may be required for expression of the desired physiological conditioning health and rejuvenation benefits. PMID:20221297

  14. In vitro and in vivo pharmacological profile of PL-3994, a novel cyclic peptide (Hept-cyclo(Cys-His-Phe-d-Ala-Gly-Arg-d-Nle-Asp-Arg-Ile-Ser-Cys)-Tyr-[Arg mimetic]-NH2) natriuretic peptide receptor-A agonist that is resistant to neutral endopeptidase and acts as a bronchodilator

    PubMed Central

    Edelson, Jeffrey D.; Makhlina, Marie; Silvester, Kevin R.; Vengurlekar, Shailesh S.; Chen, Xiaomei; Zhang, Jie; Koziol-White, Cynthia J.; Cooper, Philip R.; Hallam, Trevor J.; Hay, Douglas W.P.; Panettieri, Reynold A.

    2014-01-01

    The pharmacological and airways relaxant profiles of PL-3994 (Hept-cyclo(Cys-His-Phe-d-Ala-Gly-Arg-dNle-Asp-Arg-Ile-Ser-Cys)-Tyr-[Arg mimetic]-NH2), a novel natriuretic peptide receptor-A (NPR-A) agonist, were evaluated. PL-3994, a full agonist, has high affinity for recombinant human (h), dog, or rat NPR-As (Kis of 1, 41, and 10 nm, respectively), and produced concentration-dependent cGMP generation in human, dog and rat NPR-As (respective EC50s of 2, 3 and 14 nm). PL-3994 has a Ki of 7 nm for hNPR-C but was without effect on cGMP generation in hNPR-B. PL-3994 (1 µm) was without significant effect against 75 diverse molecular targets. PL-3994 or BNP, a natural NPR ligand, produced concentration-dependent relaxation of pre-contracted guinea-pig trachea (IC50s of 42.7 and 10.7 nm, respectively). PL-3994, and also BNP, (0.1 nm–100 µm) elicited a potent, concentration-dependent but small relaxation of pre-contracted human precision-cut lung slices (hPCLS). Intratracheal PL-3994 (1–1000 µg/kg) produced a dose-dependent inhibition of the bronchoconstrictor response evoked by aerosolized methacholine, but was without significant effect on cardiovascular parameters. PL-3994 was resistant to degradation by human neutral endopeptidase (hNEP) (92% remaining after 2 h), whereas the natural ligands, ANP and CNP, were rapidly metabolized (≤1% remaining after 2 h). PL-3994 is a potent, selective NPR agonist, resistant to NEP, with relaxant effects in guinea-pig and human airway smooth muscle systems. PL-3994 has the profile predictive of longer clinical bronchodilator activity than observed previously with ANP, and suggests its potential utility in the treatment of asthma, in addition to being a useful research tool to evaluate NPR biology. PMID:23154072

  15. In vitro and in vivo pharmacological profile of PL-3994, a novel cyclic peptide (Hept-cyclo(Cys-His-Phe-d-Ala-Gly-Arg-d-Nle-Asp-Arg-Ile-Ser-Cys)-Tyr-[Arg mimetic]-NH(2)) natriuretic peptide receptor-A agonist that is resistant to neutral endopeptidase and acts as a bronchodilator.

    PubMed

    Edelson, Jeffrey D; Makhlina, Marie; Silvester, Kevin R; Vengurlekar, Shailesh S; Chen, Xiaomei; Zhang, Jie; Koziol-White, Cynthia J; Cooper, Philip R; Hallam, Trevor J; Hay, Douglas W P; Panettieri, Reynold A

    2013-04-01

    The pharmacological and airways relaxant profiles of PL-3994 (Hept-cyclo(Cys-His-Phe-d-Ala-Gly-Arg-d-Nle-Asp-Arg-Ile-Ser-Cys)-Tyr-[Arg mimetic]-NH(2)), a novel natriuretic peptide receptor-A (NPR-A) agonist, were evaluated. PL-3994, a full agonist, has high affinity for recombinant human (h), dog, or rat NPR-As (K(i)s of 1, 41, and 10 nm, respectively), and produced concentration-dependent cGMP generation in human, dog and rat NPR-As (respective EC(50)s of 2, 3 and 14 nm). PL-3994 has a K(i) of 7 nm for hNPR-C but was without effect on cGMP generation in hNPR-B. PL-3994 (1 μm) was without significant effect against 75 diverse molecular targets. PL-3994 or BNP, a natural NPR ligand, produced concentration-dependent relaxation of pre-contracted guinea-pig trachea (IC(50)s of 42.7 and 10.7 nm, respectively). PL-3994, and also BNP, (0.1 nm-100 μm) elicited a potent, concentration-dependent but small relaxation of pre-contracted human precision-cut lung slices (hPCLS). Intratracheal PL-3994 (1-1000 μg/kg) produced a dose-dependent inhibition of the bronchoconstrictor response evoked by aerosolized methacholine, but was without significant effect on cardiovascular parameters. PL-3994 was resistant to degradation by human neutral endopeptidase (hNEP) (92% remaining after 2 h), whereas the natural ligands, ANP and CNP, were rapidly metabolized (≤1% remaining after 2 h). PL-3994 is a potent, selective NPR agonist, resistant to NEP, with relaxant effects in guinea-pig and human airway smooth muscle systems. PL-3994 has the profile predictive of longer clinical bronchodilator activity than observed previously with ANP, and suggests its potential utility in the treatment of asthma, in addition to being a useful research tool to evaluate NPR biology. PMID:23154072

  16. Bio-mimetic Flow Control

    NASA Astrophysics Data System (ADS)

    Choi, Haecheon

    2009-11-01

    Bio-mimetic engineering or bio-mimetics is the application of biological methods and systems found in nature to the study and design of engineering systems and modern technology (from Wikipedia). The concept itself is old, but successful developments have been made recently, especially in the research field of flow control. The objective of flow control based on the bio-mimetic approach is to develop novel concepts for reducing drag, increasing lift and enhancing aerodynamic performance. For skin friction reduction, a few ideas have been suggested such as the riblet from shark, compliant surface from dolphin, microbubble injection and multiple front-body curvature from penguin, and V-shaped protrusion from sailfish. For form drag reduction, several new attempts have been also made recently. Examples include the V-shaped spanwise grooves from saguaro cactus, overall shape of box fish, longitudinal grooves on scallop shell, bill of swordfish, hooked comb on owl wing, trailing-edge protrusion on dragonfly wing, and fillet. For the enhancement of aerodynamic performance, focuses have been made on the birds, fish and insects: e.g., double layered feather of landing bird, leading-edge serration of humpback-whale flipper, pectoral fin of flying fish, long tail on swallowtail-butterfly wing, wing flapping motion of dragonfly, and alula in birds. Living animals adapt their bodies to better performance in multi purposes, but engineering requires single purpose in most cases. Therefore, bio-mimetic approaches often produce excellent results more than expected. However, they are sometimes based on people's wrong understanding of nature and produce unwanted results. Successes and failures from bio-mimetic approaches in flow control will be discussed in the presentation.

  17. Fibronectin- and Collagen-Mimetic Ligands Regulate BMSC Chondrogenesis in 3D Hydrogels

    PubMed Central

    Connelly, J.T.; Petrie, T.A.; García, A.J.; Levenston, M.E.

    2016-01-01

    Modification of tissue engineering scaffolds with bioactive molecules is a potential strategy for modulating cell behavior and guiding tissue regeneration. While adhesion to RGD peptides has been shown to inhibit in vitro chondrogenesis, the effects of extracellular matrix (ECM)-mimetic ligands with complex secondary and tertiary structures are unknown. This study aimed to determine whether collagen- and fibronectin-mimetic ligands would retain biologic functionality in three-dimensional (3D) hydrogels, whether different ECM-mimetic ligands differentially influence in vitro chondrogenesis, and if effects of ligands on differentiation depend on soluble biochemical stimuli. A linear RGD peptide, a recombinant fibronectin fragment containing the seven to 10 Type III repeats (FnIII7-10) and a triple helical, collagen mimetic peptide with the GFOGER motif were covalently coupled to agarose gels using the sulfo-SANPAH crosslinker, and bone marrow stromal cells (BMSCs) were cultured within the 3D hydrogels.. The ligands retained biologic functionality within the agarose gels and promoted density-dependent BMSC spreading. Interactions with all adhesive ligands inhibited stimulation by chondrogenic factors of collagen Type II and aggrecanmRNA levels and deposition of sulfated glycosaminoglycans. In medium containing fetal bovine serum, interactions with the GFOGER peptide enhanced mRNA expression of the osteogenic gene osteocalcin whereas FnIII7-10 inhibited osteocalcin expression. In conclusion, modification of agarose hydrogels with ECM-mimetic ligands can influence the differentiation of BMSCs in a manner that depends strongly on the presence and nature of soluble biochemical stimuli. PMID:21932193

  18. Effect of mimetic CDK9 inhibitors on HIV-1 activated transcription

    PubMed Central

    Van Duyne, Rachel; Guendel, Irene; Jaworski, Elizabeth; Sampey, Gavin; Klase, Zachary; Chen, Hao; Zeng, Chen; Kovalskyy, Dmytro; el Kouni, Mahmoud H.; Lepene, Benjamin; Patanarut, Alexis; Nekhai, Sergei; Price, David H.; Kashanchi, Fatah

    2013-01-01

    Potent antiretroviral therapy (ART) has transformed HIV-1 infection into a chronic manageable disease; however drug resistance remains a common problem that limits the effectiveness and clinical benefits of this type of treatment. The discovery of viral reservoirs in the body, in which HIV-1 may persist, has helped to explain why therapeutic eradication of HIV-1 has proved so difficult. In the current study we utilized a combination of structure based analysis of Cyclin/CDK complexes with our previously published Tat peptide derivatives. We modeled the Tat peptide inhibitors with CDKs and found a particular pocket which showed the most stable binding site (Cavity 1) using in silico analysis. Furthermore, we were able to find peptide mimetics that bound to similar regions using in silico searches of a chemical library, followed by cell based biological assays. Using these methods we obtained the first generation mimetic drugs and tested these compounds on HIV-1 LTR activated transcription. Using biological assays followed by similar in silico analysis to find a 2nd generation drugs resembling the original mimetic, we found the new targets of Cavity 1 and Cavity 2 regions on CDK9. We examined the 2nd generation mimetic against various viral isolates, and observed a generalized suppression of most HIV-1 isolates. Finally, the drug inhibited viral replication in humanized mouse models of Rag2-/-γc-/- with no toxicity to the animals at tested concentrations. Our results suggest that it may be possible to model peptide inhibitors into available crystal structures and further find drug mimetics using in silico analysis. PMID:23247501

  19. Emerging Roles of Apolipoprotein E and Apolipoprotein A-I in the Pathogenesis and Treatment of Lung Disease.

    PubMed

    Yao, Xianglan; Gordon, Elizabeth M; Figueroa, Debbie M; Barochia, Amisha V; Levine, Stewart J

    2016-08-01

    Emerging roles are being recognized increasingly for apolipoproteins in the pathogenesis and treatment of lung diseases on the basis of their ability to suppress inflammation, oxidative stress, and tissue remodeling, and to promote adaptive immunity and host defense. Apolipoproteins, such as apolipoprotein E (apoE) and apolipoprotein A-I (apoA-I), are important components of lipoprotein particles that facilitate the transport of cholesterol, triglycerides, and phospholipids between plasma and cells. ApoE-containing lipoprotein particles are internalized into cells by low-density lipoprotein receptors (LDLRs), whereas apoA-I can interact with the ATP-binding cassette subfamily A member 1 (ABCA1) transporter to efflux cholesterol and phospholipids out of cells. ApoE and apoA-I also mediate receptor-independent effects, such as binding to and neutralizing LPS. Both apoE and apoA-I are expressed by lung cells, which allows apoE/LDLR- and apoA-I/ABCA1-dependent pathways to modulate normal lung health and the pathogenesis of respiratory diseases, including asthma, acute lung injury, cancer, emphysema, pulmonary fibrosis, and pulmonary hypertension. Data from human studies and research using experimental murine model systems have shown that both apoE and apoA-I pathways play primarily protective roles in lung biology and respiratory disease. Furthermore, apolipoprotein mimetic peptides, corresponding to the LDLR-binding domain of apoE or the class A amphipathic α-helical structure of apoA-I, have antiinflammatory and antioxidant effects that attenuate the severity of lung disease in murine models. Thus, the development of inhaled apolipoprotein mimetic peptides as a novel treatment paradigm could represent a significant advance for patients with respiratory disease who do not respond to current therapies. PMID:27073971

  20. Cyclic thrombospondin-1 mimetics: grafting of a thrombospondin sequence into circular disulfide-rich frameworks to inhibit endothelial cell migration

    PubMed Central

    Chan, Lai Yue; Craik, David J.; Daly, Norelle L.

    2015-01-01

    Tumour formation is dependent on nutrient and oxygen supply from adjacent blood vessels. Angiogenesis inhibitors can play a vital role in controlling blood vessel formation and consequently tumour progression by inhibiting endothelial cell proliferation, sprouting and migration. The primary aim of the present study was to design cyclic thrombospondin-1 (TSP-1) mimetics using disulfide-rich frameworks for anti-angiogenesis therapies and to determine whether these peptides have better potency than the linear parent peptide. A short anti-angiogenic heptapeptide fragment from TSP-1 (GVITRIR) was incorporated into two cyclic disulfide-rich frameworks, namely MCoTI-II (Momordica cochinchinensis trypsin inhibitor-II) and SFTI-1 (sunflower trypsin inhibitor-1). The cyclic peptides were chemically synthesized and folded in oxidation buffers, before being tested in a series of in vitro evaluations. Incorporation of the bioactive heptapeptide fragment into the cyclic frameworks resulted in peptides that inhibited microvascular endothelial cell migration, and had no toxicity against normal primary human endothelial cells or cancer cells. Importantly, all of the designed cyclic TSP-1 mimetics were far more stable than the linear heptapeptide in human serum. The present study has demonstrated a novel approach to stabilize the active region of TSP-1. The anti-angiogenic activity of the native TSP-1 active fragment was maintained in the new TSP-1 mimetics and the results provide a new chemical approach for the design of TSP-1 mimetics. PMID:26464514

  1. Cyclic thrombospondin-1 mimetics: grafting of a thrombospondin sequence into circular disulfide-rich frameworks to inhibit endothelial cell migration.

    PubMed

    Chan, Lai Yue; Craik, David J; Daly, Norelle L

    2015-01-01

    Tumour formation is dependent on nutrient and oxygen supply from adjacent blood vessels. Angiogenesis inhibitors can play a vital role in controlling blood vessel formation and consequently tumour progression by inhibiting endothelial cell proliferation, sprouting and migration. The primary aim of the present study was to design cyclic thrombospondin-1 (TSP-1) mimetics using disulfide-rich frameworks for anti-angiogenesis therapies and to determine whether these peptides have better potency than the linear parent peptide. A short anti-angiogenic heptapeptide fragment from TSP-1 (GVITRIR) was incorporated into two cyclic disulfide-rich frameworks, namely MCoTI-II (Momordica cochinchinensis trypsin inhibitor-II) and SFTI-1 (sunflower trypsin inhibitor-1). The cyclic peptides were chemically synthesized and folded in oxidation buffers, before being tested in a series of in vitro evaluations. Incorporation of the bioactive heptapeptide fragment into the cyclic frameworks resulted in peptides that inhibited microvascular endothelial cell migration, and had no toxicity against normal primary human endothelial cells or cancer cells. Importantly, all of the designed cyclic TSP-1 mimetics were far more stable than the linear heptapeptide in human serum. The present study has demonstrated a novel approach to stabilize the active region of TSP-1. The anti-angiogenic activity of the native TSP-1 active fragment was maintained in the new TSP-1 mimetics and the results provide a new chemical approach for the design of TSP-1 mimetics. PMID:26464514

  2. Unimodular mimetic F(R) inflation

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-07-01

    We propose the unimodular-mimetic F(R) gravity theory, to resolve cosmological constant problem and dark matter problem in a unified geometric manner. We demonstrate that such a theory naturally admits accelerating universe evolution. Furthermore, we construct unimodular-mimetic F(R) inflationary cosmological scenarios compatible with the Planck and BICEP2/Keck-Array observational data. We also address the graceful exit issue, which is guaranteed by the existence of unstable de Sitter vacua.

  3. Amylin structure-function relationships and receptor pharmacology: implications for amylin mimetic drug development.

    PubMed

    Bower, Rebekah L; Hay, Debbie L

    2016-06-01

    Amylin is an important, but poorly understood, 37 amino acid glucoregulatory hormone with great potential to target metabolic diseases. A working example that the amylin system is one worth developing is the FDA-approved drug used in insulin-requiring diabetic patients, pramlintide. However, certain characteristics of pramlintide pharmacokinetics and formulation leave considerable room for further development of amylin-mimetic compounds. Given that amylin-mimetic drug design and development is an active area of research, surprisingly little is known about the structure/function relationships of amylin. This is largely due to the unfavourable aggregative and solubility properties of the native peptide sequence, which are further complicated by the composition of amylin receptors. These are complexes of the calcitonin receptor with receptor activity-modifying proteins. This review explores what is known of the structure-function relationships of amylin and provides insights that can be drawn from the closely related peptide, CGRP. We also describe how this information is aiding the development of more potent and stable amylin mimetics, including peptide hybrids. PMID:27061187

  4. Pro-Cognitive Effects of Non-Peptide Analogues of Soluble Amyloid Peptide Precursor Fragment sAPP.

    PubMed

    Tiunova, A A; Komissarova, N V; Nenaidenko, V G; Makhmutova, A A; Beznosko, B K; Bachurin, S O; Anokhin, K V

    2016-08-01

    We studied pro-cognitive effect of two heterocyclic low-molecular-weight compounds that serve as non-peptide analogues of soluble fragment of amyloid peptide precursor (sAPP). Intracerebroventricular and systemic administration of peptide mimetics P2 and P5 improved weak memory on the model of passive avoidance in chicks and in the object location task in mice. Both compounds were effective if administered close to the moment of training or 4 h after it. The time windows and dose range for the pro-cognitive effects of the mimetics were similar to those observed in previous studies with sAPP peptide fragments. PMID:27590763

  5. Ac2-26 Mimetic Peptide of Annexin A1 Inhibits Local and Systemic Inflammatory Processes Induced by Bothrops moojeni Venom and the Lys-49 Phospholipase A2 in a Rat Model

    PubMed Central

    Carlos, Carla Patrícia; Ullah, Anwar; Arni, Raghuvir Krishnaswamy; Gil, Cristiane Damas; Oliani, Sonia Maria

    2015-01-01

    Annexin A1 (AnxA1) is an endogenous glucocorticoid regulated protein that modulates anti-inflammatory process and its therapeutic potential has recently been recognized in a range of systemic inflammatory disorders. The effect of the N-terminal peptide Ac2-26 of AnxA1 on the toxic activities of Bothrops moojeni crude venom (CV) and its myotoxin II (MjTX-II) were evaluated using a peritonitis rat model. Peritonitis was induced by the intraperitoneal injection of either CV or MjTX-II, a Lys-49 phospholipase A2. Fifteen minutes after the injection, the rats were treated with either Ac2-26 or PBS. Four hours later, the CV and MjTX-II-induced peritonitis were characterized by neutrophilia (in the peritoneal exudate, blood and mesentery) and increased number of mesenteric degranulated mast cells and macrophages. At 24 hours post-injection, the local inflammatory response was attenuated in the CV-induced peritonitis while the MjTX-II group exhibited neutrophilia (peritoneal exudates and blood). Ac2-26 treatment prevented the influx of neutrophils in MjTX-II–induced peritonitis and diminished the proportion of mesenteric degranulated mast cells and macrophages in CV-induced peritonitis. Additionally, CV and MjTX-II promoted increased levels of IL-1β and IL-6 in the peritoneal exudates which were significantly reduced after Ac2-26 treatment. At 4 and 24 hours, the endogenous expression of AnxA1 was upregulated in the mesenteric neutrophils (CV and MjTX-II groups) and mast cells (CV group). In the kidneys, CV and MjTX-II administrations were associated with an increased number of macrophages and morphological alterations in the juxtamedullary nephrons in proximal and distal tubules. Ac2-26 promoted significant recovery of the juxtamedullary structures, decreased the number of macrophages and diminished the AnxA1 in epithelial cells from distal tubules and renal capsules. Our results show that Ac2-26 treatment significantly attenuates local and systemic inflammatory

  6. Programming of enzyme specificity by substrate mimetics: investigations on the Glu-specific V8 protease reveals a novel general principle of biocatalysis.

    PubMed

    Wehofsky, N; Bordusa, F

    1999-01-25

    In this paper the universal validity of the substrate mimetic concept in enzymatic C-N ligations was expanded to anionic leaving groups based on the specificity determinants of Glu-specific endopeptidase from Staphylococcus aureus (V8 protease). In an empirical way a specific mimetic moiety was designed from simple structure-function relationship studies. The general function of the newly developed substrate mimetics to serve as an artificial recognition site for V8 protease have been examined by hydrolysis kinetic studies. Enzymatic peptide syntheses qualify the strategy of substrate mimetics as a powerful concept for programming the enzyme specificity in the direction of a more universal application of enzymes in the general area of biocatalysis. PMID:9989609

  7. Potent Bivalent Smac Mimetics: Effect of the Linker on Binding to Inhibitor of Apoptosis Proteins (IAPs) and Anticancer Activity

    PubMed Central

    Sun, Haiying; Liu, Liu; Lu, Jianfeng; Bai, Longchuan; Li, Xiaoqin; Nikolovska-Coleska, Zaneta; McEachern, Donna; Yang, Chao-Yie; Qiu, Su; Yi, Han; Sun, Duxin; Wang, Shaomeng

    2011-01-01

    We have synthesized and evaluated a series of non-peptidic, bivalent Smac mimetics as antagonists of the inhibitor of apoptosis proteins and new anticancer agents. All these bivalent Smac mimetics bind to full-length XIAP with low nanomolar affinities and function as ultra-potent antagonists of XIAP. While these Smac mimetics bind to cIAP1/2 with similar low nanomolar affinities, their potencies to induce degradation of cIAP1/2 proteins in cells differ by more than 100-fold. The most potent bivalent Smac mimetics inhibit cell growth with IC50 values from 1–3 nM in the MDA-MB-231 breast cancer cell line and are 100-times more potent than the least potent compounds. Determination of intracellular concentrations for several representative compounds showed that the linkers in these bivalent Smac mimetics significantly affect their intracellular concentrations, hence the overall cellular activity. Compound 27 completely inhibits tumor growth in the MDA-MB-231 xenografts, while causing no signs of toxicity in the animals. PMID:21462933

  8. Cosmological perturbations in mimetic Horndeski gravity

    NASA Astrophysics Data System (ADS)

    Arroja, Frederico; Bartolo, Nicola; Karmakar, Purnendu; Matarrese, Sabino

    2016-04-01

    We study linear scalar perturbations around a flat FLRW background in mimetic Horndeski gravity. In the absence of matter, we show that the Newtonian potential satisfies a second-order differential equation with no spatial derivatives. This implies that the sound speed for scalar perturbations is exactly zero on this background. We also show that in mimetic G3 theories the sound speed is equally zero. We obtain the equation of motion for the comoving curvature perturbation (first order differential equation) and solve it to find that the comoving curvature perturbation is constant on all scales in mimetic Horndeski gravity. We find solutions for the Newtonian potential evolution equation in two simple models. Finally we show that the sound speed is zero on all backgrounds and therefore the system does not have any wave-like scalar degrees of freedom.

  9. Apolipoprotein A-I: A Molecule of Diverse Function.

    PubMed

    Mangaraj, Manaswini; Nanda, Rachita; Panda, Suchismita

    2016-07-01

    Apolipoprotein A-I (apo A-I) an indispensable component and a major structural protein of high-density lipoprotein (HDL), plays a vital role in reverse cholesterol transport and cellular cholesterol homeostasis since its identification. Its multifunctional role in immunity, inflammation, apoptosis, viral, bacterial infection etc. has crossed its boundary of its potential of protecting cardiovascular system and lowering cardiovascular disease risk, attributing HDL to be known as a protective fat removal particle. Its structural homology with prostacyclin stabilization factor has contributed to its anti-clotting and anti-aggregatory effect on platelet which has potentiated its cardio-protective role as well as its therapeutic efficacy against Alzheimer's disease. The binding affinity and neutralising action against endotoxin lipopolysaccharide, reduces the toxic manifestations of septic shock. As a negative acute phase protein, it blocks T-cell signalling of macrophages. However the recently identified anti-tumor activity of apo A-I has been highlighted in various models of melanoma, lung cancer, ovarian cancer, lymphoblastic leukaemia, gastric as well as pancreatic cancers. These cancer fighting effects are directed towards regression of tumor size and distant metastasis by its immuno modulatory activity as well as its clearing effect on serum lysophospholipids. This lowering effect on lysophospholipid concentration is utilized by apo A-I mimetic peptides to be used in retarding tumor cell proliferation and as a potential cancer therapeutic agent. Not only that, it inhibits the tumor associated neo-angiogenesis as well as brings down the matrix degrading enzymes associated with tumor metastasis. However this efficient therapeutic potential of apo A-I as an anti tumor agent awaits further future experimental studies in humans. PMID:27382195

  10. Antibody mimetics: promising complementary agents to animal-sourced antibodies.

    PubMed

    Baloch, Abdul Rasheed; Baloch, Abdul Wahid; Sutton, Brian J; Zhang, Xiaoying

    2016-01-01

    Despite their wide use as therapeutic, diagnostic and detection agents, the limitations of polyclonal and monoclonal antibodies have inspired scientists to design the next generation biomedical agents, so-called antibody mimetics that offer many advantages over conventional antibodies. Antibody mimetics can be constructed by protein-directed evolution or fusion of complementarity-determining regions through intervening framework regions. Substantial progress in exploiting human, butterfly (Pieris brassicae) and bacterial systems to design and select mimetics using display technologies has been made in the past 10 years, and one of these mimetics [Kalbitor® (Dyax)] has made its way to market. Many challenges lie ahead to develop mimetics for various biomedical applications, especially those for which conventional antibodies are ineffective, and this review describes the current characteristics, construction and applications of antibody mimetics compared to animal-sourced antibodies. The possible limitations of mimetics and future perspectives are also discussed. PMID:25264572

  11. Structures of Potent Selective Peptide Mimetics Bound to Carboxypeptidase B

    SciTech Connect

    Adler, M.; Buckman, B.; Bryant, J.; Chang, Z.; Chu, K.; Emayan, K.; Hrvatin, P.; Islam, I.; Morser, J.; Sukovich, D.; West, C.; Yuan, S.; Whitlow, M.

    2009-05-11

    This article reports the crystal structures of inhibitors of the functional form of thrombin-activatable fibrinolysis inhibitor (TAFIa). In vivo experiments indicate that selective inhibitors of TAFIa would be useful in the treatment of heart attacks. Since TAFIa rapidly degrades in solution, the homologous protein porcine pancreatic carboxypeptidase B (pp-CpB) was used in these crystallography studies. Both TAFIa and pp-CpB are zinc-based exopeptidases that are specific for basic residues. The final development candidate, BX 528, is a potent inhibitor of TAFIa (2 nM) and has almost no measurable effect on the major selectivity target, carboxypeptidase N. BX 528 was designed to mimic the tripeptide Phe-Val-Lys. A sulfonamide replaces the Phe-Val amide bond and a phosphinate connects the Val and Lys groups. The phosphinate also chelates the active-site zinc. The electrostatic interactions with the protein mimic those of the natural substrate. The primary amine in BX 528 forms a salt bridge to Asp255 at the base of the S1 pocket. The carboxylic acid interacts with Arg145 and the sulfonamide is hydrogen bonded to Arg71. Isopropyl and phenyl groups replace the side chains of Val and Phe, respectively. A series of structures are presented here that illustrate the evolution of BX 528 from thiol-based inhibitors that mimic a free C-terminal arginine. The first step in development was the replacement of the thiol with a phosphinate. This caused a precipitous drop in binding affinity. Potency was reclaimed by extending the inhibitors into the downstream binding sites for the natural substrate.

  12. Designing a small molecule erythropoietin mimetic.

    PubMed

    Guarnieri, Frank

    2015-01-01

    Erythropoietin (EPO) is a protein made by the kidneys in response to low red blood cell count that is secreted into the bloodstream and binds to a receptor on hematopoietic stem cells in the bone marrow inducing them to become new red blood cells. EPO made with recombinant DNA technology was brought to market in the 1980s to treat anemia caused by kidney disease and cancer chemotherapy. Because EPO infusion was able to replace blood transfusions in many cases, it rapidly became a multibillion dollar per year drug and as the first biologic created with recombinant technology it launched the biotech industry. For many years intense research was focused on creating a small molecule orally available EPO mimetic. The Robert Wood Johnson (RWJ) group seemed to definitively establish that only large peptides with a minimum of 60 residues could replace EPO, as anything less was not a full agonist. An intense study of the published work led me to hypothesize that the size of the mimetic is not the real issue, but the symmetry making and breaking of the EPO receptor induced by the ligand is the key to activating the stem cells. This analysis meant that residues in the binding site of the receptor deemed absolutely essential for ligand binding and activation from mutagenesis experiments, were probably not really that important. My fundamental hypotheses were: (a) the symmetric state of the homodimeric receptor is the most stable state and thus must be the off-state, (b) a highly localized binding site exists at a pivot point where the two halves of the receptor meet, (c) small molecules can be created that have high potency for this site that will be competitive with EPO and thus can displace the protein-protein interaction, (d) small symmetric molecules will stabilize the symmetric off-state of the receptor, and (e) a key asymmetry in the small molecule will stabilize a mirror image asymmetry in the receptor resulting in the stabilization of the on-state and proliferation of

  13. Metal complexes as "protein surface mimetics".

    PubMed

    Hewitt, Sarah H; Wilson, Andrew J

    2016-07-28

    A key challenge in chemical biology is to identify small molecule regulators for every single protein. However, protein surfaces are notoriously difficult to recognise with synthetic molecules, often having large flat surfaces that are poorly matched to traditional small molecules. In the surface mimetic approach, a supramolecular scaffold is used to project recognition groups in such a manner as to make multivalent non-covalent contacts over a large area of protein surface. Metal based supramolecular scaffolds offer unique advantages over conventional organic molecules for protein binding, including greater stereochemical and geometrical diversity conferred through the metal centre and the potential for direct assessment of binding properties and even visualisation in cells without recourse to further functionalisation. This feature article will highlight the current state of the art in protein surface recognition using metal complexes as surface mimetics. PMID:27353704

  14. Non-local F(R)-mimetic gravity

    NASA Astrophysics Data System (ADS)

    Myrzakulov, Ratbay; Sebastiani, Lorenzo

    2016-06-01

    In this paper, we study non-local F(R)-mimetic gravity. We implement mimetic gravity in the framework of non-local F(R)-theories of gravity. Given some specific class of models and using a potential on the mimetic field, we investigate some scenarios related to the early-time universe, namely the inflation and the cosmological bounce, which bring to Einstein's gravity with cold dark matter at the late-time.

  15. NEC violation in mimetic cosmology revisited

    NASA Astrophysics Data System (ADS)

    Ijjas, Anna; Ripley, Justin; Steinhardt, Paul J.

    2016-09-01

    In the context of Einstein gravity, if the null energy condition (NEC) is satisfied, the energy density in expanding space-times always decreases while in contracting space-times the energy density grows and the universe eventually collapses into a singularity. In particular, no non-singular bounce is possible. It is, though, an open question if this energy condition can be violated in a controlled way, i.e., without introducing pathologies, such as unstable negative-energy states or an imaginary speed of sound. In this letter, we will re-examine the claim that the recently proposed mimetic scenario can violate the NEC without pathologies. We show that mimetic cosmology is prone to gradient instabilities even in cases when the NEC is satisfied (except for trivial examples). Most interestingly, the source of the instability is always the Einstein-Hilbert term in the action. The matter stress-energy component does not contribute spatial gradient terms but instead makes the problematic curvature modes dynamical. We also show that mimetic cosmology can be understood as a singular limit of known, well-behaved theories involving higher-derivative kinetic terms and discuss ways of removing the instability.

  16. Cosmological perturbations in a mimetic matter model

    NASA Astrophysics Data System (ADS)

    Matsumoto, Jiro; Odintsov, Sergei D.; Sushkov, Sergey V.

    2015-03-01

    We investigate the cosmological evolution of a mimetic matter model with arbitrary scalar potential. The cosmological reconstruction—which is the method for constructing a model for an arbitrary evolution of the scale factor—is explicitly performed for different choices of potential. The cases where the mimetic matter model shows the evolution as cold dark matter (CDM), the w CDM model, dark matter and dark energy with a dynamical O m (z ) [where O m (z )≡[(H (z )/H0)2-1 ]/[(1 +z )3-1 ] ], and phantom dark energy with a phantom-nonphantom crossing are presented in detail. The cosmological perturbations for such evolutions are studied in the mimetic matter model. For instance, the evolution behavior of the matter density contrast (which is different than the usual one, i.e., δ ¨+2 H δ ˙-κ2ρ δ /2 =0 ) is investigated. The possibility of a peculiar evolution of δ in the model under consideration is shown. Special attention is paid to the behavior of the matter density contrast near the future singularity, where the decay of perturbations may occur much earlier than the singularity.

  17. Disformal transformations, veiled General Relativity and Mimetic Gravity

    SciTech Connect

    Deruelle, Nathalie; Rua, Josephine E-mail: rua@cbpf.br

    2014-09-01

    In this Note we show that Einstein's equations for gravity are generically invariant under ''disformations''. We also show that the particular subclass when this is not true yields the equations of motion of ''Mimetic Gravity''. Finally we give the ''mimetic'' generalization of the Schwarzschild solution.

  18. Apolipoprotein A-I inhibits experimental colitis and colitis-propelled carcinogenesis.

    PubMed

    Gkouskou, K K; Ioannou, M; Pavlopoulos, G A; Georgila, K; Siganou, A; Nikolaidis, G; Kanellis, D C; Moore, S; Papadakis, K A; Kardassis, D; Iliopoulos, I; McDyer, F A; Drakos, E; Eliopoulos, A G

    2016-05-12

    In both humans with long-standing ulcerative colitis and mouse models of colitis-associated carcinogenesis (CAC), tumors develop predominantly in the distal part of the large intestine but the biological basis of this intriguing pathology remains unknown. Herein we report intrinsic differences in gene expression between proximal and distal colon in the mouse, which are augmented during dextran sodium sulfate (DSS)/azoxymethane (AOM)-induced CAC. Functional enrichment of differentially expressed genes identified discrete biological pathways operating in proximal vs distal intestine and revealed a cluster of genes involved in lipid metabolism to be associated with the disease-resistant proximal colon. Guided by this finding, we have further interrogated the expression and function of one of these genes, apolipoprotein A-I (ApoA-I), a major component of high-density lipoprotein. We show that ApoA-I is expressed at higher levels in the proximal compared with the distal part of the colon and its ablation in mice results in exaggerated DSS-induced colitis and disruption of epithelial architecture in larger areas of the large intestine. Conversely, treatment with an ApoA-I mimetic peptide ameliorated the phenotypic, histopathological and inflammatory manifestations of the disease. Genetic interference with ApoA-I levels in vivo impacted on the number, size and distribution of AOM/DSS-induced colon tumors. Mechanistically, ApoA-I was found to modulate signal transducer and activator of transcription 3 (STAT3) and nuclear factor-κB activation in response to the bacterial product lipopolysaccharide with concomitant impairment in the production of the pathogenic cytokine interleukin-6. Collectively, these data demonstrate a novel protective role for ApoA-I in colitis and CAC and unravel an unprecedented link between lipid metabolic processes and intestinal pathologies. PMID:26279300

  19. A cosmological solution to mimetic dark matter

    NASA Astrophysics Data System (ADS)

    Saadi, Hassan

    2016-01-01

    In this paper, a cosmological solution to Mimetic Dark Matter (MDM) for an exponential potential is provided. Then a solution for the 0-i perturbed Einstein differential equation of MDM is obtained based on an exponential potential that satisfies inflation for some initial conditions. Another general potential is suggested that incorporates inflation too. Then quantum perturbations are included. The constants in the model can be tuned to be in agreement with the fluctuation amplitude of the cosmic microwave background (CMB) radiation. Finally, the spectral index is calculated for the suggested potentials. Moreover, MDM is shown to be a viable model to produce dark matter, inflation, and CMB's fluctuation.

  20. Peptide agonists of the thrombopoietin receptor.

    PubMed

    Dower, W J; Cwirla, S E; Balasubramanian, P; Schatz, P J; Baccanari, D P; Barrett, R W

    1998-01-01

    We have screened a variety of L-amino acid peptide libraries against the extracellular domain of the human thrombopoietin (HuTPO) receptor, c-Mpl. A large number of peptide ligands were recovered and categorized into two families. Peptides from each family compete with the binding of HuTPO and with the binding of peptides from the other familiy. Representative peptides were synthesized and found to activate the full-length HuTPO receptor expressed in Ba/F3 cells to promote proliferation. These peptide families show no apparent homology to the primary sequence of TPO. We have focused our optimization efforts on one of the peptides, a linear 14-mer (IEGPTLRQWLAARA) with an IC50 of 2 nM in a competition binding assay and an EC50 of 400 nM in the proliferation assay. In order to enhance the potency of the compound, we constructed dimeric peptides by linking the carboxy-termini of the 14-mers to a lysine branch. These molecules exhibited slightly higher affinity (0.5 nM) and greatly increased potency (0.1 nM). The EC50 of the dimeric peptide was equivalent to that of the 332 aa form of baculovirus-expressed recombinant HuTPO. As previously shown for the erythropoietin-mimetic peptides, the TPO-mimetic peptides probably activate the TPO receptor by binding and inducing receptor dimerization. This supposition is supported by the observation that covalent dimerization of the peptide enhances its potency by 4,000-fold over that of the monomer. The peptide dimer is also active in stimulating in vitro proliferation of progenitors and maturation of megakaryocytes from human bone marrow, and in promoting an increase in platelet count when administered to normal mice. PMID:11012174

  1. Effects of increasing hydrophobicity on the physical-chemical and biological properties of a class A amphipathic helical peptide.

    PubMed

    Datta, G; Chaddha, M; Hama, S; Navab, M; Fogelman, A M; Garber, D W; Mishra, V K; Epand, R M; Epand, R F; Lund-Katz, S; Phillips, M C; Segrest, J P; Anantharamaiah, G M

    2001-07-01

    We have recently shown that a class A amphipathic peptide 5F with increased amphipathicity protected mice from diet-induced atherosclerosis (Garber et al. J. Lipid Res. 2001. 42: 545-552). We have now examined the effects of increasing the hydrophobicity of a series of homologous class A amphipathic peptides, including 5F, on physical and functional properties related to atherosclerosis inhibition by systematically replacing existing nonpolar amino acids with phenylalanine. The peptides, based on the sequence Ac-D-W-L-K-A-F-Y-D-K-V-A-E-K-L-K-E-A-F-NH(2) (Ac-18A-NH(2) or 2F) were: 3F(3)(Ac-F(3)18A-NH(2)), 3F(14)(Ac-F(14)18A-NH(2)), 4F(Ac-F(3,14)18A-NH(2)), 5F(Ac-F(11,14,17) 18A-NH(2)), 6F(Ac-F(10,11,14,17)18A-NH(2)), and 7F(Ac-F(3,10,11,14,17) 18A-NH(2)). Measurements of aqueous solubility, HPLC retention time, exclusion pressure for penetration into an egg phosphatidylcholine (EPC) monolayer, and rates of EPC solubilization revealed an abrupt increase in the hydrophobicity between peptides 4F and 5F; this was accompanied by increased ability to associate with phospholipids. The peptides 6F and 7F were less effective, indicating a limit to increased hydrophobicity for promoting lipid interaction in these peptides. Despite this marked increase in lipid affinity, these peptides were less effective than apoA-I in activating the plasma enzyme, lecithin:cholesterol acyltransferase, with 5F activating LCAT the best (80% of apoA-I). Peptides 4F, 5F, and 6F were equally potent in inhibiting LDL-induced monocyte chemotactic activity. These studies suggest that an appropriate balance between peptide-peptide and peptide-lipid interactions is required for optimal biological activity of amphipathic peptides. These studies provide a rationale for the design of small apoA-I-mimetics with increased potency for atherosclerosis inhibition. PMID:11441137

  2. Tunable elastin-mimetic multiblock hybrid copolymers for biomedical applications

    NASA Astrophysics Data System (ADS)

    Grieshaber, Sarah Elizabeth

    Elastin-mimetic hybrid polymers (EMHPs) have been developed to capture the multiblock molecular architecture of tropoelastin, allowing tunability in chemical, structural, biological, and mechanical properties. Multiblock EMHPs containing flexible synthetic segments were first synthesized via step growth polymerization of diazido-poly(ethylene glycol) (PEG) and alkyne-terminated AKA3KA (K = lysine, A = alanine) (AK2) peptide employing copper (I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC, or orthogonal click chemistry). Covalent crosslinking of the EMHPs with hexamethylene diisocyanate (HMDI) through the lysine residues in the peptide domain afforded an elastomeric hydrogel (xEMHP) with a compressive modulus of 0.12 +/- 0.018 MPa when hydrated. xEMHPs exhibited minimal cytotoxicity to primary porcine vocal fold fibroblasts. The modular nature of the synthesis allowed facile adjustment of the peptide sequence to modulate the structural and the biological properties of EMHPs. Thus, EMHPs containing integrin-binding peptides were constructed using di-azido-PEG and an alkyne-terminated AK2 peptide with a terminal, integrin-binding GRGDSP domain via the step growth click coupling reaction. Hydrogels formed by covalent crosslinking of the RGD-containing EMHPs had a compressive modulus of 1.06 +/- 0.1MPa when hydrated. Neonatal human dermal fibroblasts (NHDFs) were able to adhere to the hydrogels within 1 h, and to spread and develop F-actin filaments 24 h post seeding. NHDF proliferation was only observed on hydrogels containing RGD domains, demonstrating the importance of integrin engagement for cell growth and the potential use of these EMHPs as tissue engineering scaffolds. The tunability of the EMHP system was further investigated by development of self-assembling, pH-responsive multiblock polymers composed of alternating domains of poly(acrylic acid) (PAA) and a peptide derived from the hydrophobic domains of elastin with the sequence (VPGVG)2 (VG2). The

  3. Apolipoprotein A-I possesses an anti-obesity effect associated with increase of energy expenditure and up-regulation of UCP1 in brown fat

    PubMed Central

    Ruan, Xiangbo; Li, Zhenghu; Zhang, Yixuan; Yang, Ling; Pan, Yi; Wang, Zhenzhen; Feng, Gen-Sheng; Chen, Yan

    2011-01-01

    Abstract Apolipoprotein A-I (ApoA-I) is the most abundant protein constituent of high-density lipoprotein (HDL). Reduced plasma HDL and ApoA-I levels have been found to be associated with obesity and metabolic syndrome in human beings. However, whether or not ApoA-I has a direct effect on obesity is largely unknown. Here we analysed the anti-obesity effect of ApoA-I using two mouse models, a transgenic mouse with overexpression of ApoA-I and the mice administered with an ApoA-I mimetic peptide D-4F. The mice were induced to develop obesity by feeding with high fat diet. Both ApoA-I overexpression and D-4F treatment could significantly reduce white fat mass and slightly improve insulin sensitivity in the mice. Metabolic analyses revealed that ApoA-I overexpression and D-4F treatment enhanced energy expenditure in the mice. The mRNA level of uncoupling protein (UCP)1 in brown fat tissue was elevated by ApoA-I transgenic mice. ApoA-I and D-4F treatment was able to increase UCP1 mRNA and protein levels as well as to stimulate AMP-activated protein kinase (AMPK) phosphorylation in brown adipocytes in culture. Taken together, our results reveal that ApoA-I has an anti-obesity effect in the mouse and such effect is associated with increases in energy expenditure and UCP1 expression in the brown fat tissue. PMID:20193037

  4. Synthetic oligosaccharides as heparin-mimetics displaying anticoagulant properties.

    PubMed

    Avci, Fikri Y; Karst, Nathalie A; Linhardt, Robert J

    2003-01-01

    Heparin and low molecular weight heparins are major clinical anticoagulants and the drugs of choice for the treatment of deep venous thrombosis. The discovery of an antithrombin binding domain in heparin focused interest on understanding the mechanism of heparin's antithrombotic/ anticoagulant activity. Various heparin-mimetic oligosaccharides have been prepared in an effort to replace polydisperse heparin and low molecular weight heparins with a structurally-defined anticoagulant. The goal of attaining a heparin-mimetic with no unwanted side-effects has also provided motivation for these efforts. This article reviews structure-activity relationship (SAR) of structurally-defined heparin-mimetic oligosaccharides. PMID:14529394

  5. Caloric Restriction Mimetics Enhance Anticancer Immunosurveillance.

    PubMed

    Pietrocola, Federico; Pol, Jonathan; Vacchelli, Erika; Rao, Shuan; Enot, David P; Baracco, Elisa E; Levesque, Sarah; Castoldi, Francesca; Jacquelot, Nicolas; Yamazaki, Takahiro; Senovilla, Laura; Marino, Guillermo; Aranda, Fernando; Durand, Sylvère; Sica, Valentina; Chery, Alexis; Lachkar, Sylvie; Sigl, Verena; Bloy, Norma; Buque, Aitziber; Falzoni, Simonetta; Ryffel, Bernhard; Apetoh, Lionel; Di Virgilio, Francesco; Madeo, Frank; Maiuri, Maria Chiara; Zitvogel, Laurence; Levine, Beth; Penninger, Josef M; Kroemer, Guido

    2016-07-11

    Caloric restriction mimetics (CRMs) mimic the biochemical effects of nutrient deprivation by reducing lysine acetylation of cellular proteins, thus triggering autophagy. Treatment with the CRM hydroxycitrate, an inhibitor of ATP citrate lyase, induced the depletion of regulatory T cells (which dampen anticancer immunity) from autophagy-competent, but not autophagy-deficient, mutant KRAS-induced lung cancers in mice, thereby improving anticancer immunosurveillance and reducing tumor mass. Short-term fasting or treatment with several chemically unrelated autophagy-inducing CRMs, including hydroxycitrate and spermidine, improved the inhibition of tumor growth by chemotherapy in vivo. This effect was only observed for autophagy-competent tumors, depended on the presence of T lymphocytes, and was accompanied by the depletion of regulatory T cells from the tumor bed. PMID:27411589

  6. A spectral mimetic least-squares method

    DOE PAGESBeta

    Bochev, Pavel; Gerritsma, Marc

    2014-09-01

    We present a spectral mimetic least-squares method for a model diffusion–reaction problem, which preserves key conservation properties of the continuum problem. Casting the model problem into a first-order system for two scalar and two vector variables shifts material properties from the differential equations to a pair of constitutive relations. We also use this system to motivate a new least-squares functional involving all four fields and show that its minimizer satisfies the differential equations exactly. Discretization of the four-field least-squares functional by spectral spaces compatible with the differential operators leads to a least-squares method in which the differential equations are alsomore » satisfied exactly. Additionally, the latter are reduced to purely topological relationships for the degrees of freedom that can be satisfied without reference to basis functions. Furthermore, numerical experiments confirm the spectral accuracy of the method and its local conservation.« less

  7. A spectral mimetic least-squares method

    SciTech Connect

    Bochev, Pavel; Gerritsma, Marc

    2014-09-01

    We present a spectral mimetic least-squares method for a model diffusion–reaction problem, which preserves key conservation properties of the continuum problem. Casting the model problem into a first-order system for two scalar and two vector variables shifts material properties from the differential equations to a pair of constitutive relations. We also use this system to motivate a new least-squares functional involving all four fields and show that its minimizer satisfies the differential equations exactly. Discretization of the four-field least-squares functional by spectral spaces compatible with the differential operators leads to a least-squares method in which the differential equations are also satisfied exactly. Additionally, the latter are reduced to purely topological relationships for the degrees of freedom that can be satisfied without reference to basis functions. Furthermore, numerical experiments confirm the spectral accuracy of the method and its local conservation.

  8. Temporally degradable collagen-mimetic hydrogels tuned to chondrogenesis of human mesenchymal stem cells.

    PubMed

    Parmar, Paresh A; Skaalure, Stacey C; Chow, Lesley W; St-Pierre, Jean-Philippe; Stoichevska, Violet; Peng, Yong Y; Werkmeister, Jerome A; Ramshaw, John A M; Stevens, Molly M

    2016-08-01

    collagen-mimetic protein, cross-linked via multiple enzymatically degradable peptides, provides a highly adaptable and well defined platform to recapitulate a high degree of biological complexity, which could be applicable to numerous tissue engineering and regenerative medicine applications. PMID:27214650

  9. Nuclear receptors and AMPK: can exercise mimetics cure diabetes?

    PubMed

    Wall, Christopher E; Yu, Ruth T; Atkins, Anne R; Downes, Michael; Evans, Ronald M

    2016-07-01

    Endurance exercise can lead to systemic improvements in insulin sensitivity and metabolic homeostasis, and is an effective approach to combat metabolic diseases. Pharmacological compounds that recapitulate the beneficial effects of exercise, also known as 'exercise mimetics', have the potential to improve disease symptoms of metabolic syndrome. These drugs, which can increase energy expenditure, suppress hepatic gluconeogenesis, and induce insulin sensitization, have accordingly been highly scrutinized for their utility in treating metabolic diseases including diabetes. Nevertheless, the identity of an efficacious exercise mimetic still remains elusive. In this review, we highlight several nuclear receptors and cofactors that are putative molecular targets for exercise mimetics, and review recent studies that provide advancements in our mechanistic understanding of how exercise mimetics exert their beneficial effects. We also discuss evidence from clinical trials using these compounds in human subjects to evaluate their efficacy in treating diabetes. PMID:27106806

  10. Elucidation of the aggregation pathways of helix-turn-helix peptides: Stabilization at the turn region is critical for fibril formation

    PubMed Central

    Do, Thanh D.; Chamas, Ali; Zheng, Xueyun; Barnes, Aaron; Chang, Dayna; Veldstra, Tjitske; Takhar, Harmeet; Dressler, Nicolette; Trapp, Benjamin; Miller, Kylie; McMahon, Audrene; Meredith, Stephen C.; Shea, Joan-Emma; Cantrell, Kristi Lazar; Bowers, Michael T.

    2015-01-01

    Aggregation of proteins to fiber-like aggregates often involves a transformation of native monomers to β-sheet-rich oligomers. This general observation underestimates the importance of α-helical segments in the aggregation cascade. Here, using a combination of experimental techniques and accelerated molecular dynamics simulations, we investigate the aggregation of a 43-residue, apolipoprotein A-I mimetic peptide and its E21Q and D26N mutants. Our study indicates a strong propensity of helical segments not to adopt cross-β fibrils. The helix-turn-helix monomeric conformation of the peptides is preserved in the mature fibrils. Furthermore, we reveal opposite effects of mutations on and near the turn region in the self-assembly of these peptides. We show that the E21-R24 salt bridge is a major contributor to helix-turn-helix folding, subsequently leading to abundant fibril formation. On the other hand, the K19-D26 interaction is not required to fold the native helix-turn-helix. However, removal of the charged D26 residue decreases the stability of helix-turn-helix monomer, and consequently reduces aggregation. Finally, we provide a more refined assembly model for the helix-turn-helix peptides from apolipoprotein A-I based on the parallel stacking of helix-turn-helix dimers. PMID:26070092

  11. Crystal Structures of Complexes of Bacterial DD-Peptidases with Peptidoglycan-mimetic Ligands: The Substrate Specificity Puzzle

    PubMed Central

    Sauvage, Eric; Powell, Ailsa J.; Heilemann, Jason; Josephine, Helen R.; Charlier, Paulette; Davies, Christopher; Pratt, R.F.

    2008-01-01

    Summary The X-ray crystal structures of covalent complexes of the Actinomadura R39 DD-peptidase and Escherichia coli penicillin-binding protein 5 with β-lactams bearing peptidoglycan-mimetic side chains have been determined. The structure of the hydrolysis product of an analogous peptide bound non-covalently to the former enzyme has also been obtained. The R39 DD-peptidase structures reveal the presence of a specific binding site for the D-α-aminopimelyl side chain, characteristic of the stem peptide of Actinomadura R39. This binding site features a hydrophobic cleft for the pimelyl methylene groups and strong hydrogen bonding to the polar terminus. Both of these elements of the site are provided by amino acid side chains from two separate domains of the protein. In contrast, no clear electron density corresponding to the terminus of the peptidoglycan-mimetic side chains is present when these β-lactams are covalently bound to penicillin-binding protein 5. There is, therefore, no indication of a specific side chain binding site in this enzyme. These results are in agreement with those from kinetics studies published earlier and support the general prediction made at the time of a direct correlation between the kinetics and structural evidence. The essential high molecular weight penicillin binding proteins have demonstrated, to date, no specific reactivity with peptidoglycan-mimetic peptide substrates and β-lactam inhibitors and thus probably do not possess a specific substrate binding site of the type demonstrated here with the R39 DD-peptidase. This striking deficiency may represent a sophisticated defense mechanism against low molecular weight substrate-analogue inhibitors/antibiotics; its discovery should focus new inhibitor design. PMID:18602645

  12. Characterization of Potent SMAC Mimetics that Sensitize Cancer Cells to TNF Family-Induced Apoptosis.

    PubMed

    Welsh, Kate; Milutinovic, Snezana; Ardecky, Robert J; Gonzalez-Lopez, Marcos; Ganji, Santhi Reddy; Teriete, Peter; Finlay, Darren; Riedl, Stefan; Matsuzawa, Shu-Ichi; Pinilla, Clemencia; Houghten, Richard; Vuori, Kristiina; Reed, John C; Cosford, Nicholas D P

    2016-01-01

    Members of the Inhibitor of APoptosis (IAP) protein family suppress apoptosis within tumor cells, particularly in the context of immune cell-mediated killing by the tumor necrosis factor (TNF) superfamily cytokines. Most IAPs are opposed endogenously by the second mitochondrial activator of caspases (SMAC), which binds to selected baculovirus IAP repeat (BIR) domains of IAPs to displace interacting proteins. The development of SMAC mimetics as novel anticancer drugs has gained impetus, with several agents now in human clinical trials. To further understand the cellular mechanisms of SMAC mimetics, we focused on IAP family members cIAP1 and cIAP2, which are recruited to TNF receptor complexes where they support cell survival through NF-κB activation while suppressing apoptosis by preventing caspase activation. We established fluorescence polarization (FP) assays for the BIR2 and BIR3 domains of human cIAP1 and cIAP2 using fluorochrome-conjugated SMAC peptides as ligands. A library of SMAC mimetics was profiled using the FP assays to provide a unique structure activity relationship (SAR) analysis compared to previous assessments of binding to XIAP. Potent compounds displayed mean inhibitory binding constants (Ki) of 9 to 27 nM against the BIR3 domains of cIAP1 and cIAP2, respectively. Selected compounds were then characterized using cytotoxicity assays in which a cytokine-resistant human tumor cell line was sensitized to either TNF or lymphotoxin-α (LT-α). Cytotoxicity correlated closely with cIAP1 and cIAP2 BIR3 binding activity with the most potent compounds able to reduce cell viability by 50%. Further testing demonstrated that active compounds also inhibit RIP1 binding to BIR3 of cIAP1 and cIAP2 in vitro and reduce steady-state cIAP1 protein levels in cells. Altogether, these data inform the SAR for our SMAC mimetics with respect to cIAP1 and cIAP2, suggesting that these IAP family members play an important role in tumor cell resistance to cytotoxicity

  13. Oxpholipin 11D: An Anti-Inflammatory Peptide That Binds Cholesterol and Oxidized Phospholipids

    PubMed Central

    Ruchala, Piotr; Navab, Mohamad; Jung, Chun-Ling; Hama-Levy, Susan; Micewicz, Ewa D.; Luong, Hai; Reyles, Jonathan E.; Sharma, Shantanu; Waring, Alan J.; Fogelman, Alan M.; Lehrer, Robert I.

    2010-01-01

    Background Many Gram-positive bacteria produce pore-forming exotoxins that contain a highly conserved, 12-residue domain (ECTGLAWEWWRT) that binds cholesterol. This domain is usually flanked N-terminally by arginine and C-terminally by valine. We used this 14-residue sequence as a template to create a small library of peptides that bind cholesterol and other lipids. Methodology/Results Several of these peptides manifested anti-inflammatory properties in a predictive in vitro monocyte chemotactic assay, and some also diminished the pro-inflammatory effects of low-density lipoprotein in apoE-deficient mice. The most potent analog, Oxpholipin-11D (OxP-11D), contained D-amino acids exclusively and was identical to the 14-residue design template except that diphenylalanine replaced cysteine-3. In surface plasmon resonance binding studies, OxP-11D bound oxidized (phospho)lipids and sterols in much the same manner as D-4F, a widely studied cardioprotective apoA-I-mimetic peptide with anti-inflammatory properties. In contrast to D-4F, which adopts a stable α-helical structure in solution, the OxP-11D structure was flexible and contained multiple turn-like features. Conclusion Given the substantial evidence that oxidized phospholipids are pro-inflammatory in vivo, OxP-11D and other Oxpholipins may have therapeutic potential. PMID:20418958

  14. Adsorption of apolipoprotein A-I to biological membranes. A statistical mechanical model

    NASA Astrophysics Data System (ADS)

    Gross, Eitan

    2012-07-01

    Apolipoprotein A-I (apo A-I), the main protein component of high-density lipoprotein (HDL), reduces the risk for atherosclerosis by removing cholesterol from the membrane of foam cells. Experiments with model membrane systems have indicated, however, that membrane cholesterol reduces apo A-I binding to the membrane. Foam cells resolve this discrepancy electrostatically by co-inserting negatively charged phospholipids in their membrane. Here we present a statistical mechanical model to account for the effect of cholesterol. Our model is based on the Haugen and May model which takes into account the dipolar nature of the zwitterionic phospholipid head group in the membrane, in which the positive end of the zwitterionic dipole moment can move randomly on a hemispherical surface with a radius equal to the arm of the dipole moment and with the negative end fixed at the hydrocarbon layer. Adsorption of a positively charged apo A-I macroion to the surface of the membrane modifies the electric field within the head group region and induces lateral demixing of phospholipid molecules in the membrane. Results from numerical integration of model equations show that i) as a result of the strong charge-dipole electrostatic coupling, the positive end of the dipoles tilts away from the adsorbed macroion in a cooperative manner; and ii) cholesterol reduces macroion adsorption to the membrane by reducing the surface area of the membrane and restricting the dipoles range of rotation. Model predictions for the change in free energy of adsorption to zwitterionic membrane are in good agreement with previously reported experimental data with liposomes. The model can assist in designing new mimetic peptides.

  15. Neurotrophic factor small-molecule mimetics mediated neuroregeneration and synaptic repair: emerging therapeutic modality for Alzheimer's disease.

    PubMed

    Kazim, Syed Faraz; Iqbal, Khalid

    2016-01-01

    Alzheimer's disease (AD) is an incurable and debilitating chronic progressive neurodegenerative disorder which is the leading cause of dementia worldwide. AD is a heterogeneous and multifactorial disorder, histopathologically characterized by the presence of amyloid β (Aβ) plaques and neurofibrillary tangles composed of Aβ peptides and abnormally hyperphosphorylated tau protein, respectively. Independent of the various etiopathogenic mechanisms, neurodegeneration is a final common outcome of AD neuropathology. Synaptic loss is a better correlate of cognitive impairment in AD than Aβ or tau pathologies. Thus a highly promising therapeutic strategy for AD is to shift the balance from neurodegeneration to neuroregeneration and synaptic repair. Neurotrophic factors, by virtue of their neurogenic and neurotrophic activities, have potential for the treatment of AD. However, the clinical therapeutic usage of recombinant neurotrophic factors is limited because of the insurmountable hurdles of unfavorable pharmacokinetic properties, poor blood-brain barrier (BBB) permeability, and severe adverse effects. Neurotrophic factor small-molecule mimetics, in this context, represent a potential strategy to overcome these short comings, and have shown promise in preclinical studies. Neurotrophic factor small-molecule mimetics have been the focus of intense research in recent years for AD drug development. Here, we review the relevant literature regarding the therapeutic beneficial effect of neurotrophic factors in AD, and then discuss the recent status of research regarding the neurotrophic factor small-molecule mimetics as therapeutic candidates for AD. Lastly, we summarize the preclinical studies with a ciliary neurotrophic factor (CNTF) small-molecule peptide mimetic, Peptide 021 (P021). P021 is a neurogenic and neurotrophic compound which enhances dentate gyrus neurogenesis and memory processes via inhibiting leukemia inhibitory factor (LIF) signaling pathway and increasing

  16. Tunicate-mimetic nanofibrous hydrogel adhesive with improved wet adhesion.

    PubMed

    Oh, Dongyeop X; Kim, Sangsik; Lee, Dohoon; Hwang, Dong Soo

    2015-07-01

    The main impediment to medical application of biomaterial-based adhesives is their poor wet adhesion strength due to hydration-induced softening and dissolution. To solve this problem, we mimicked the wound healing process found in tunicates, which use a nanofiber structure and pyrogallol group to heal any damage on its tunic under sea water. We fabricated a tunicate-mimetic hydrogel adhesive based on a chitin nanofiber/gallic acid (a pyrogallol acid) composite. The pyrogallol group-mediated cross-linking and the nanofibrous structures improved the dissolution resistance and cohesion strength of the hydrogel compared to the amorphous polymeric hydrogels in wet condition. The tunicate-mimetic adhesives showed higher adhesion strength between fully hydrated skin tissues than did fibrin glue and mussel-mimetic adhesives. The tunicate mimetic hydrogels were produced at low cost from recyclable and abundant raw materials. This tunicate-mimetic adhesive system is an example of how natural materials can be engineered for biomedical applications. PMID:25841348

  17. Dispersal of mimetic seeds of three species of Ormosia (Leguminosae)

    USGS Publications Warehouse

    Foster, M.S.; DeLay, L.S.

    1998-01-01

    Seeds with 'imitation arils' appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard 'mimetic' seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae) were observed to ascertain mechanisms of seed dispersal and the role of seemingly mimetic characteristics of the seeds in that dispersal. Seed predation and seed germination were also examined. Ormosia isthamensis and O. macrocalyx (but not O. bopiensis) deceived arboreally-foraging frugivorous birds into taking their mimetic seeds, although rates of seed dispersal were low. These results are consistent with the mimetic seed hypothesis. On the other hand, the rates of disappearance of seeds from the ground under the Ormosia trees, hardness of the seeds, and enhancement of germination with the abrasion of the seed coat are all consistent with the hard-seed for grit hypothesis.

  18. Apolipoprotein E Mimetic Promotes Functional and Histological Recovery in Lysolecithin-Induced Spinal Cord Demyelination in Mice

    PubMed Central

    Gu, Zhen; Li, Fengqiao; Zhang, Yi Ping; Shields, Lisa B.E.; Hu, Xiaoling; Zheng, Yiyan; Yu, Panpan; Zhang, Yongjie; Cai, Jun; Vitek, Michael P.; Shields, Christopher B.

    2014-01-01

    Objective Considering demyelination is the pathological hallmark of multiple sclerosis (MS), reducing demyelination and/or promoting remyelination is a practical therapeutic strategy to improve functional recovery for MS. An apolipoprotein E (apoE)-mimetic peptide COG112 has previously demonstrated therapeutic efficacy on functional and histological recovery in a mouse experimental autoimmune encephalomyelitis (EAE) model of human MS. In the current study, we further investigated whether COG112 promotes remyelination and improves functional recovery in lysolecithin induced focal demyelination in the white matter of spinal cord in mice. Methods A focal demyelination model was created by stereotaxically injecting lysolecithin into the bilateral ventrolateral funiculus (VLF) of T8 and T9 mouse spinal cords. Immediately after lysolecithin injection mice were treated with COG112, prefix peptide control or vehicle control for 21 days. The locomotor function of the mice was measured by the beam walking test and Basso Mouse Scale (BMS) assessment. The nerve transmission of the VLF of mice was assessed in vivo by transcranial magnetic motor evoked potentials (tcMMEPs). The histological changes were also examined by by eriochrome cyanine staining, immunohistochemistry staining and electron microscopy (EM) method. Results The area of demyelination in the spinal cord was significantly reduced in the COG112 group. EM examination showed that treatment with COG112 increased the thickness of myelin sheaths and the numbers of surviving axons in the lesion epicenter. Locomotor function was improved in COG112 treated animals when measured by the beam walking test and BMS assessment compared to controls. TcMMEPs also demonstrated the COG112-mediated enhancement of amplitude of evoked responses. Conclusion The apoE-mimetic COG112 demonstrates a favorable combination of activities in suppressing inflammatory response, mitigating demyelination and in promoting remyelination and

  19. Cell mimetic lateral stabilization of outer cell mimetic bilayer on polymer surfaces by peptide bonding and their blood compatibility.

    PubMed

    Kaladhar, K; Sharma, Chandra P

    2006-10-01

    The biological lipid bilayer membranes are stabilized laterally with the help of integral proteins. We have simulated this with an optimized ternary phospholipid/glycolipid/cholesterol system, and stabilized laterally on functionalized poly methyl methacrylate (PMMA) surfaces, using albumin, heparin, and polyethylene glycol as anchors. We have earlier demonstrated the differences due to orientation and packing of the ternary phospholipid monolayers in relation to blood compatibility (Kaladhar and Sharma, Langmuir 2004;20:11115-11122). The structure of albumin is changed here to expose its interior hydrophobic core by treating with organic solvent. The interaction between the hydrophobic core of the albumin molecule and the hydrophobic core of the lipid molecules is confirmed by incorporating the molecule into bilayer membranes. The secondary structure of the membrane incorporated albumin is studied by CD spectral analysis. The structure of the altered albumin molecule contains more beta-sheet as compared to the native albumin. This conformation is also retained in membranes. The partitioning of the different anchors based on its polarity and ionic interactions in the monolayer is studied from the pressure-area (pi-A) isotherm of the lipid monolayers at the air/water interface using Langmuir-Blodgett (LB) trough facility. Such two monolayers are deposited onto the functionalized PMMA surface using LB trough and crosslinked by carbodiimide chemistry. The structure of the deposited bilayer is studied by depth analysis using contact mode AFM in dry conditions. The stabilized bilayer shows stability up to 1 month by contact angle studies. Preliminary blood compatibility studies reveal that the calcification, protein adsorption, as well as blood-cell adhesion is significantly reduced after the surface modification. The reduced adsorption of ions, proteins, and cells to the modified surfaces may be due to the fluidity of the microenvironment along with the contribution of the mobile PEG groups at the surface and the phosphorylcholine groups of the phospholipids. The stability of the anchored bilayer under low shear stress conditions promises that the laterally stabilized supported bilayer system can be used for low shear applications like small diameter vascular graft and modification of biosensors, and so forth. PMID:16758449

  20. Peptide-membrane Interactions by Spin-labeling EPR

    PubMed Central

    Smirnova, Tatyana I.; Smirnov, Alex I.

    2016-01-01

    Site-directed spin labeling (SDSL) in combination with Electron Paramagnetic Resonance (EPR) spectroscopy is a well-established method that has recently grown in popularity as an experimental technique, with multiple applications in protein and peptide science. The growth is driven by development of labeling strategies, as well as by considerable technical advances in the field, that are paralleled by an increased availability of EPR instrumentation. While the method requires an introduction of a paramagnetic probe at a well-defined position in a peptide sequence, it has been shown to be minimally destructive to the peptide structure and energetics of the peptide-membrane interactions. In this chapter, we describe basic approaches for using SDSL EPR spectroscopy to study interactions between small peptides and biological membranes or membrane mimetic systems. We focus on experimental approaches to quantify peptide-membrane binding, topology of bound peptides, and characterize peptide aggregation. Sample preparation protocols including spin-labeling methods and preparation of membrane mimetic systems are also described. PMID:26477253

  1. Elucidating the mechanobiology of malignant brain tumors using a brain matrix-mimetic hyaluronic acid hydrogel platform

    PubMed Central

    Ananthanarayanan, Badriprasad; Kim, Yushan; Kumar, Sanjay

    2011-01-01

    Glioblastoma multiforme (GBM) is a malignant brain tumor characterized by diffuse infiltration of single cells into the brain parenchyma, which is a process that relies in part on aberrant biochemical and biophysical interactions between tumor cells and the brain extracellular matrix (ECM). A major obstacle to understanding ECM regulation of GBM invasion is the absence of model matrix systems that recapitulate the distinct composition and physical structure of brain ECM while allowing independent control of adhesive ligand density, mechanics, and microstructure. To address this need, we synthesized brain-mimetic ECMs based on hyaluronic acid (HA) with a range of stiffnesses that encompasses normal and tumorigenic brain tissue and functionalized these materials with short Arg-Gly-Asp (RGD) peptides to facilitate cell adhesion. Scanning electron micrographs of the hydrogels revealed a dense, sheet-like microstructure with apparent nanoscale porosity similar to brain extracellular space. On flat hydrogel substrates, glioma cell spreading area and actin stress fiber assembly increased strongly with increasing density of RGD peptide. Increasing HA stiffness under constant RGD density produced similar trends and increased the speed of random motility. In a three-dimensional (3D) spheroid paradigm, glioma cells invaded HA hydrogels with morphological patterns distinct from those observed on flat surfaces or in 3D collagen-based ECMs but highly reminiscent of those seen in brain slices. This material system represents a brain-mimetic model ECM with tunable ligand density and stiffness amenable to investigations of the mechanobiological regulation of brain tumor progression. PMID:21820737

  2. Influences of Membrane Mimetic Environments on Membrane Protein Structures

    PubMed Central

    Zhou, Huan-Xiang; Cross, Timothy A.

    2013-01-01

    The number of membrane protein structures in the Protein Data Bank is becoming significant and growing. Here, the transmembrane domain structures of the helical membrane proteins are evaluated to assess the influences of the membrane mimetic environments. Toward this goal, many of the biophysical properties of membranes are discussed and contrasted with those of the membrane mimetics commonly used for structure determination. Although the mimetic environments can perturb the protein structures to an extent that potentially gives rise to misinterpretation of functional mechanisms, there are also many structures that have a native-like appearance. From this assessment, an initial set of guidelines is proposed for distinguishing native-like from nonnative-like membrane protein structures. With experimental techniques for validation and computational methods for refinement and quality assessment and enhancement, there are good prospects for achieving native-like structures for these very important proteins. PMID:23451886

  3. The Life of the Mimetic Starfish, 2000-2012.

    PubMed

    Brown, Richard

    2015-01-01

    This article is written from the perspective of the artist, programmer, and exhibitor of the Mimetic Starfish, a gestural responsive ALife artwork first created for the Millennium Dome in 2000 and recently exhibited at the Emoção Art.ficial in Brazil in 2012. The author concludes with the suggestion that despite the advances in technology and the ubiquitous presence of touch and gestural interfaces, it is the underlying aesthetic and socially engaging qualities of the Mimetic Starfish that ensure its currency, presence, relevance, and continuing exhibition. PMID:26280068

  4. Carboxyl-Terminal Cleavage of Apolipoprotein A-I by Human Mast Cell Chymase Impairs Its Anti-Inflammatory Properties

    PubMed Central

    Nguyen, Su Duy; Maaninka, Katariina; Lappalainen, Jani; Nurmi, Katariina; Metso, Jari; Öörni, Katariina; Navab, Mohamad; Fogelman, Alan M.; Jauhiainen, Matti; Lee-Rueckert, Miriam

    2016-01-01

    Objective— Apolipoprotein A-I (apoA-I) has been shown to possess several atheroprotective functions, including inhibition of inflammation. Protease-secreting activated mast cells reside in human atherosclerotic lesions. Here we investigated the effects of the neutral proteases released by activated mast cells on the anti-inflammatory properties of apoA-I. Approach and Results— Activation of human mast cells triggered the release of granule-associated proteases chymase, tryptase, cathepsin G, carboxypeptidase A, and granzyme B. Among them, chymase cleaved apoA-I with the greatest efficiency and generated C-terminally truncated apoA-I, which failed to bind with high affinity to human coronary artery endothelial cells. In tumor necrosis factor-α–activated human coronary artery endothelial cells, the chymase-cleaved apoA-I was unable to suppress nuclear factor-κB–dependent upregulation of vascular cell adhesion molecule-1 (VCAM-1) and to block THP-1 cells from adhering to and transmigrating across the human coronary artery endothelial cells. Chymase-cleaved apoA-I also had an impaired ability to downregulate the expression of tumor necrosis factor-α, interleukin-1β, interleukin-6, and interleukin-8 in lipopolysaccharide-activated GM-CSF (granulocyte-macrophage colony-stimulating factor)– and M-CSF (macrophage colony-stimulating factor)–differentiated human macrophage foam cells and to inhibit reactive oxygen species formation in PMA (phorbol 12-myristate 13-acetate)–activated human neutrophils. Importantly, chymase-cleaved apoA-I showed reduced ability to inhibit lipopolysaccharide-induced inflammation in vivo in mice. Treatment with chymase blocked the ability of the apoA-I mimetic peptide L-4F, but not of the protease-resistant D-4F, to inhibit proinflammatory gene expression in activated human coronary artery endothelial cells and macrophage foam cells and to prevent reactive oxygen species formation in activated neutrophils. Conclusions— The

  5. Preferred conformation of endomorphin-1 in aqueous and membrane-mimetic environments.

    PubMed

    Fiori, S; Renner, C; Cramer, J; Pegoraro, S; Moroder, L

    1999-08-01

    The newly discovered endomorphin-1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (Tyr-Pro-Phe-Phe-NH2) are potent opioid peptides with the highest affinity and selectivity for the mu receptor among all known endogenous ligands. To investigate a possible correlation between these biological properties and the conformational preferences of the small peptides, a comparative structural analysis was performed of endomorphin-1 in aqueous buffer and in membrane-mimicking SDS and AOT normal and reverse micelles by the use of CD, FT-IR, fluorescence and(1)H-NMR spectroscopy. It is well established for opioid peptides that, independently of the receptor selectivity, the Tyr1 residue plays the role of the primary pharmacophore and that the orientation of the second aromatic pharmacophore relative to the tyrosine side-chain dictates the mu or delta-receptor selectivity. By varying the environment of endomorphin-1 from water to the amphipathic SDS micelles and even more efficiently to the AOT reverse micelles, the display of the aromatic side-chains changes from an interaction of the Tyr1 and Phe4 residues to a switch of the Trp3 indole group into close contact with the phenolic moiety to prevent this type of interaction and to force an orientation of the Phe4 side-chain into the opposite direction. This conformational switch is accompanied by a stabilization of the cis -Pro2 isomer and the resulting spatial array of the pharmacophoric groups correlate well with the structural model of mu receptor-bound opioid peptides. The results indicate that AOT reverse micelles with a woof 10, where almost exclusively ordered water is secluded in the cavity, constitute with their electrostatic and hydrophobic potential an excellent mimetic of amphipathic surfaces as present on lipid bilayers and on ligand-recognition and ligand-binding sites of proteins. PMID:10438613

  6. The Co-Occurrence of Quotatives with Mimetic Performances.

    ERIC Educational Resources Information Center

    Buchstaller, Isabelle

    2003-01-01

    This paper discusses mimesis, the direct representation and total imitation of an event. It studies the co-occurrence of quotative verbs with mimetic enactment based on two corpora of U.S. American English, both available through the University of Pennsylvania Data Consortium. The Switchboard Corpus has 542 speakers ranging in age from 20-60 years…

  7. Dark energy oscillations in mimetic F (R ) gravity

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-08-01

    In this paper we address the problem of dark energy oscillations in the context of mimetic F (R ) gravity with potential. The issue of dark energy oscillations can be a problem in some models of ordinary F (R ) gravity, and a remedy that can make the oscillations milder is to introduce additional modifications in the functional form of the F (R ) gravity. As we demonstrate, the power-law modifications are not necessary in the mimetic F (R ) case, and by appropriately choosing the mimetic potential and the Lagrange multiplier, it is possible to make the oscillations almost vanish at the end of the matter domination era and during the late-time acceleration era. We examine the behavior of the dark energy equation of state parameter and of the total effective equation of state parameter as functions of the redshift, and we compare the resulting picture with the ordinary F (R ) gravity case. As we also show that the present day values of the dark energy equation of state parameter and of the total effective equation of state parameter are in better agreement with the observational data, in comparison to the ordinary F (R ) gravity case. Finally, we study the evolution of the growth factor as a function of the redshift for all the mimetic models we use.

  8. Cell outer membrane mimetic chitosan nanoparticles: preparation, characterization and cytotoxicity.

    PubMed

    Zhao, Jing; Liang, Fei; Kong, Lingheng; Zheng, Lina; Fan, Tao

    2015-01-01

    A negatively charged copolymer poly (MPC-co-AMPS) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-acrylamide-2-methyl propane sulfonic acid (AMPS) was designed and synthesized. Chitosan nanoparticles with cell outer membrane mimetic structure were prepared by electrostatic interaction between the sulfonic acid groups of poly (MPC-co-AMPS) and the protonated amino groups of chitosan. Effects of factors on influencing the particle size, distribution, and stability were investigated. The experimental results showed that cell membrane mimetic chitosan nanoparticles with controllable and homogeneous size ranged from 100 to 300 nm were prepared at the concentration of 0.1-2.0 mg/mL and the charge ratio of 0.5-1.1. Chitosan nanoparticles prepared can exist stably for more than 45 days when placed at 4 °C and pH < 7.5. The cytotoxicity of the chitosan nanoparticles reduced significantly after surface modification with cell membrane mimetic structure, meeting the basic requirements of biomedical materials. The results suggest cell membrane mimetic chitosan nanoparticles prepared with polyanion and polycation obtain good biological compatibility and immune stealth ability, which has important academic significance and great application prospects. PMID:26230052

  9. Redox regulation of Smac mimetic-induced cell death.

    PubMed

    Fulda, Simone

    2015-01-01

    Cell death and survival programs are controlled by the cellular redox state, which is typically dysregulated during oncogenesis. A recent study reports that the inhibition of antioxidant defenses resulting from glutathione depletion can prime acute lymphoblastic leukemia cells for death induced by Smac mimetics. PMID:27308489

  10. Bio-Mimetic Sensors Based on Molecularly Imprinted Membranes

    PubMed Central

    Algieri, Catia; Drioli, Enrico; Guzzo, Laura; Donato, Laura

    2014-01-01

    An important challenge for scientific research is the production of artificial systems able to mimic the recognition mechanisms occurring at the molecular level in living systems. A valid contribution in this direction resulted from the development of molecular imprinting. By means of this technology, selective molecular recognition sites are introduced in a polymer, thus conferring it bio-mimetic properties. The potential applications of these systems include affinity separations, medical diagnostics, drug delivery, catalysis, etc. Recently, bio-sensing systems using molecularly imprinted membranes, a special form of imprinted polymers, have received the attention of scientists in various fields. In these systems imprinted membranes are used as bio-mimetic recognition elements which are integrated with a transducer component. The direct and rapid determination of an interaction between the recognition element and the target analyte (template) was an encouraging factor for the development of such systems as alternatives to traditional bio-assay methods. Due to their high stability, sensitivity and specificity, bio-mimetic sensors-based membranes are used for environmental, food, and clinical uses. This review deals with the development of molecularly imprinted polymers and their different preparation methods. Referring to the last decades, the application of these membranes as bio-mimetic sensor devices will be also reported. PMID:25196110

  11. Selection of peptides for serological detection of equine infectious anemia.

    PubMed

    Santos, E M; Cardoso, R; Souza, G R L; Goulart, L R; Heinemann, M B; Leite, R C; Reis, J K P

    2012-01-01

    Equine infectious anemia caused by equine infectious anemia virus is an important disease due to its high severity and incidence in animals. We used a phage display library to isolate peptides that can be considered potential markers for equine infectious anemia diagnosis. We selected peptides using IgG purified from a pool comprised of 20 sera from animals naturally infected with equine infectious anemia virus. The diagnostic potential of these peptides was investigated by ELISA, Western blot and dot blot with purified IgG and serum samples. Based on the results, we chose a peptide mimetic for glycoprotein gp45 epitopes of equine infectious anemia virus, with potential for use as an antigen in indirect diagnostic assays. Synthesis of this peptide has possible applications for the development of new diagnostic tools for this disease. PMID:22653674

  12. Design and characterization of short antimicrobial peptides using leucine zipper templates with selectivity towards microorganisms.

    PubMed

    Ahmad, Aqeel; Azmi, Sarfuddin; Srivastava, Saurabh; Kumar, Amit; Tripathi, Jitendra Kumar; Mishra, Nripendra N; Shukla, Praveen K; Ghosh, Jimut Kanti

    2014-11-01

    Design of antimicrobial peptides with selective activity towards microorganisms is an important step towards the development of new antimicrobial agents. Leucine zipper sequence has been implicated in cytotoxic activity of naturally occurring antimicrobial peptides; moreover, this motif has been utilized for the design of novel antimicrobial peptides with modulated cytotoxicity. To understand further the impact of substitution of amino acids at 'a' and/or 'd' position of a leucine zipper sequence of an antimicrobial peptides on its antimicrobial and cytotoxic properties four short peptides (14-residue) were designed on the basis of a leucine zipper sequence without or with replacement of leucine residues in its 'a' and 'd' positions with D-leucine or alanine or proline residue. The original short leucine zipper peptide (SLZP) and its D-leucine substituted analog, DLSA showed comparable activity against the tested Gram-positive and negative bacteria and the fungal strains. The alanine substituted analog (ASA) though showed appreciable activity against the tested bacteria, it showed to some extent lower activity against the tested fungi. However, the proline substituted analog (PSA) showed lower activity against the tested bacterial or fungal strains. Interestingly, DLSA, ASA and PSA showed significantly lower cytotoxicity than SLZP against both human red blood cells (hRBCs) and murine 3T3 cells. Cytotoxic and bactericidal properties of these peptides matched with peptide-induced damage/permeabilization of mammalian cells and bacteria or their mimetic lipid vesicles suggesting cell membrane could be the target of these peptides. As evidenced by tryptophan fluorescence and acrylamide quenching studies the peptides showed similarities either in interaction or in their localization within the bacterial membrane mimetic negatively charged lipid vesicles. Only SLZP showed localization inside the mammalian membrane mimetic zwitterionic lipid vesicles. The results show

  13. Tetrahydro-β-carboline-based spirocyclic lactam as type II' β-turn: application to the synthesis and biological evaluation of somatostatine mimetics.

    PubMed

    Lesma, Giordano; Cecchi, Roberto; Cagnotto, Alfredo; Gobbi, Marco; Meneghetti, Fiorella; Musolino, Manuele; Sacchetti, Alessandro; Silvani, Alessandra

    2013-03-15

    The synthesis of novel spirocyclic lactams, embodying D-tryptophan (Trp) amino acid as the central core and acting as peptidomimetics, is presented. It relies on the strategic combination of Seebach's self-reproduction of chirality chemistry and Pictet-Spengler condensation as key steps. Investigation of the conformational behavior by molecular modeling, X-ray crystallography, and NMR and IR spectroscopies suggests very stable and highly predictable type II' β-turn conformations for all compounds. Relying on this feature, we also pursued their application to two potential mimetics of the hormone somatostatin, a pharmaceutically relevant natural peptide, which contains a Trp-based type II' β-turn pharmacophore. PMID:23409740

  14. Caloric restriction and exercise "mimetics'': Ready for prime time?

    PubMed

    Handschin, Christoph

    2016-01-01

    Exercise and diet are powerful interventions to prevent and ameliorate various pathologies. The development of pharmacological agents that confer exercise- or caloric restriction-like phenotypic effects is thus an appealing therapeutic strategy in diseases or even when used as life-style and longevity drugs. Such so-called exercise or caloric restriction "mimetics" have so far mostly been described in pre-clinical, experimental settings with limited translation into humans. Interestingly, many of these compounds activate related signaling pathways, most often postulated to act on the common downstream effector peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in skeletal muscle. In this review, resveratrol and other exercise- and caloric restriction "mimetics" are discussed with a special focus on feasibility, chances and limitations of using such compounds in patients as well as in healthy individuals. PMID:26658171

  15. Antagonism of scavenger receptor CD36 by 5A peptide prevents chronic kidney disease progression in mice independent of blood pressure regulation.

    PubMed

    Souza, Ana Carolina P; Bocharov, Alexander V; Baranova, Irina N; Vishnyakova, Tatyana G; Huang, Yuning G; Wilkins, Kenneth J; Hu, Xuzhen; Street, Jonathan M; Alvarez-Prats, Alejandro; Mullick, Adam E; Patterson, Amy P; Remaley, Alan T; Eggerman, Thomas L; Yuen, Peter S T; Star, Robert A

    2016-04-01

    Scavenger receptor CD36 participates in lipid metabolism and inflammatory pathways important for cardiovascular disease and chronic kidney disease (CKD). Few pharmacological agents are available to slow the progression of CKD. However, apolipoprotein A-I-mimetic peptide 5A antagonizes CD36 in vitro. To test the efficacy of 5A, and to test the role of CD36 during CKD, we compared wild-type to CD36 knockout mice and wild-type mice treated with 5A, in a progressive CKD model that resembles human disease. Knockout and 5A-treated wild-type mice were protected from CKD progression without changes in blood pressure and had reductions in cardiovascular risk surrogate markers that are associated with CKD. Treatment with 5A did not further protect CD36 knockout mice from CKD progression, implicating CD36 as its main site of action. In a separate model of kidney fibrosis, 5A-treated wild-type mice had less macrophage infiltration and interstitial fibrosis. Peptide 5A exerted anti-inflammatory effects in the kidney and decreased renal expression of inflammasome genes. Thus, CD36 is a new therapeutic target for CKD and its associated cardiovascular risk factors. Peptide 5A may be a promising new agent to slow CKD progression. PMID:26994575

  16. A recombinant mimetics of the HIV-1 gp41 prehairpin fusion intermediate fused with human IgG Fc fragment elicits neutralizing antibody response in the vaccinated mice

    SciTech Connect

    Qi, Zhi; Pan, Chungen; Lu, Hong; Shui, Yuan; Li, Lin; Li, Xiaojuan; Xu, Xueqing; Liu, Shuwen; Jiang, Shibo

    2010-07-30

    Research highlights: {yields} One recombinant mimetics of gp41 prehairpin fusion intermediate (PFI) consisting of gp41 N46 sequence, foldon and IgG Fc, designated N46FdFc, was expressed. {yields} N46FdFc-induced antibodies in mice that neutralized HIV-1 infection, inhibited PIE7 binding to PFI, blocked gp41 six-helix bundle formation, and suppressed HIV-1 mediated cell-cell fusion. {yields} These findings provide an important clue for developing recombinant gp41 PFI mimetics-based HIV vaccines. -- Abstract: HIV-1 gp41 prehairpin fusion intermediate (PFI) composed of three N-terminal heptad repeats (NHR) plays a crucial role in viral fusion and entry and represents an attractive target for anti-HIV therapeutics (e.g., enfuvirtide) and vaccines. In present study, we constructed and expressed two recombinant gp41 PFI mimetics, designated N46Fd and N46FdFc. N46Fd consists of N46 (residues 536-581) in gp41 NHR and foldon (Fd), a trimerization motif. N46FdFc is composed of N46Fd fused with human IgG Fc fragment as an immunoenhancer. We immunized mice with N46 peptide, N46Fd and N46FdFc, respectively, and found that only N46FdFc elicited neutralizing antibody response in mice against infection by HIV-1 strains IIIB (clade B, X4), 92US657 (clade B, R5), and 94UG103 (clade A, X4R5). Anti-N46FdFc antibodies inhibited PIE7 binding to PFI, blocked gp41 six-helix bundle formation, and suppressed HIV-1 mediated cell-cell fusion. These findings provide an important clue for developing recombinant gp41 PFI mimetics-based HIV vaccines.

  17. Exosome mimetics: a novel class of drug delivery systems

    PubMed Central

    Kooijmans, Sander AA; Vader, Pieter; van Dommelen, Susan M; van Solinge, Wouter W; Schiffelers, Raymond M

    2012-01-01

    The identification of extracellular phospholipid vesicles as conveyors of cellular information has created excitement in the field of drug delivery. Biological therapeutics, including short interfering RNA and recombinant proteins, are prone to degradation, have limited ability to cross biological membranes, and may elicit immune responses. Therefore, delivery systems for such drugs are under intensive investigation. Exploiting extracellular vesicles as carriers for biological therapeutics is a promising strategy to overcome these issues and to achieve efficient delivery to the cytosol of target cells. Exosomes are a well studied class of extracellular vesicles known to carry proteins and nucleic acids, making them especially suitable for such strategies. However, the considerable complexity and the related high chance of off-target effects of these carriers are major barriers for translation to the clinic. Given that it is well possible that not all components of exosomes are required for their proper functioning, an alternative strategy would be to mimic these vesicles synthetically. By assembly of liposomes harboring only crucial components of natural exosomes, functional exosome mimetics may be created. The low complexity and use of well characterized components strongly increase the pharmaceutical acceptability of such systems. However, exosomal components that would be required for the assembly of functional exosome mimetics remain to be identified. This review provides insights into the composition and functional properties of exosomes, and focuses on components which could be used to enhance the drug delivery properties of exosome mimetics. PMID:22619510

  18. The thermodynamics of simple biomembrane mimetic systems

    PubMed Central

    Raudino, Antonio; Sarpietro, Maria Grazia; Pannuzzo, Martina

    2011-01-01

    Insight into the forces governing a system is essential for understanding its behavior and function. Thermodynamic investigations provide a wealth of information that is not, or is hardly, available from other methods. This article reviews thermodynamic approaches and assays to measure collective properties such as heat adsorption / emission and volume variations. These methods can be successfully applied to the study of lipid vesicles (liposomes) and biological membranes. With respect to instrumentation, differential scanning calorimetry, pressure perturbation calorimetry, isothermal titration calorimetry, dilatometry, and acoustic techniques aimed at measuring the isothermal and adiabatic processes, two- and three-dimensional compressibilities are considered. Applications of these techniques to lipid systems include the measurement of different thermodynamic parameters and a detailed characterization of thermotropic, barotropic, and lyotropic phase behavior. The membrane binding and / or partitioning of solutes (proteins, peptides, drugs, surfactants, ions, etc.) can also be quantified and modeled. Many thermodynamic assays are available for studying the effect of proteins and other additives on membranes, characterizing non-ideal mixing, domain formation, bilayer stability, curvature strain, permeability, solubilization, and fusion. Studies of membrane proteins in lipid environments elucidate lipid–protein interactions in membranes. Finally, a plethora of relaxation phenomena toward equilibrium thermodynamic structures can be also investigated. The systems are described in terms of enthalpic and entropic forces, equilibrium constants, heat capacities, partial volume changes, volume and area compressibility, and so on, also shedding light on the stability of the structures and the molecular origin and mechanism of the structural changes. PMID:21430953

  19. The Neural Cell Adhesion Molecule-Derived Peptide FGL Facilitates Long-Term Plasticity in the Dentate Gyrus in Vivo

    ERIC Educational Resources Information Center

    Dallerac, Glenn; Zerwas, Meike; Novikova, Tatiana; Callu, Delphine; Leblanc-Veyrac, Pascale; Bock, Elisabeth; Berezin, Vladimir; Rampon, Claire; Doyere, Valerie

    2011-01-01

    The neural cell adhesion molecule (NCAM) is known to play a role in developmental and structural processes but also in synaptic plasticity and memory of the adult animal. Recently, FGL, a NCAM mimetic peptide that binds to the Fibroblast Growth Factor Receptor 1 (FGFR-1), has been shown to have a beneficial impact on normal memory functioning, as…

  20. Alkaline Phosphatase-Mimicking Peptide Nanofibers for Osteogenic Differentiation.

    PubMed

    Gulseren, Gulcihan; Yasa, I Ceren; Ustahuseyin, Oya; Tekin, E Deniz; Tekinay, Ayse B; Guler, Mustafa O

    2015-07-13

    Recognition of molecules and regulation of extracellular matrix synthesis are some of the functions of enzymes in addition to their catalytic activity. While a diverse array of enzyme-like materials have been developed, these efforts have largely been confined to the imitation of the chemical structure and catalytic activity of the enzymes, and it is unclear whether enzyme-mimetic molecules can also be used to replicate the matrix-regulatory roles ordinarily performed by natural enzymes. Self-assembled peptide nanofibers can provide multifunctional enzyme-mimetic properties, as the active sequences of the target enzymes can be directly incorporated into the peptides. Here, we report enhanced bone regeneration efficiency through peptide nanofibers carrying both catalytic and matrix-regulatory functions of alkaline phosphatase, a versatile enzyme that plays a critical role in bone formation by regulating phosphate homeostasis and calcifiable bone matrix formation. Histidine presenting peptide nanostructures were developed to function as phosphatases. These molecules are able to catalyze phosphate hydrolysis and serve as bone-like nodule inducing scaffolds. Alkaline phosphatase-like peptide nanofibers enabled osteogenesis for both osteoblast-like and mesenchymal cell lines. PMID:26039144

  1. Determining the Orientation and Localization of Membrane-Bound Peptides

    PubMed Central

    Hohlweg, Walter; Kosol, Simone; Zangger, Klaus

    2012-01-01

    Many naturally occurring bioactive peptides bind to biological membranes. Studying and elucidating the mode of interaction is often an essential step to understand their molecular and biological functions. To obtain the complete orientation and immersion depth of such compounds in the membrane or a membrane-mimetic system, a number of methods are available, which are separated in this review into four main classes: solution NMR, solid-state NMR, EPR and other methods. Solution NMR methods include the Nuclear Overhauser Effect (NOE) between peptide and membrane signals, residual dipolar couplings and the use of paramagnetic probes, either within the membrane-mimetic or in the solvent. The vast array of solid state NMR methods to study membrane-bound peptide orientation and localization includes the anisotropic chemical shift, PISA wheels, dipolar waves, the GALA, MAOS and REDOR methods and again the use of paramagnetic additives on relaxation rates. Paramagnetic additives, with their effect on spectral linewidths, have also been used in EPR spectroscopy. Additionally, the orientation of a peptide within a membrane can be obtained by the anisotropic hyperfine tensor of a rigidly attached nitroxide label. Besides these magnetic resonance techniques a series of other methods to probe the orientation of peptides in membranes has been developed, consisting of fluorescence-, infrared- and oriented circular dichroism spectroscopy, colorimetry, interface-sensitive X-ray and neutron scattering and Quartz crystal microbalance. PMID:22044140

  2. Light-switched inhibitors of protein tyrosine phosphatase PTP1B based on phosphonocarbonyl phenylalanine as photoactive phosphotyrosine mimetic.

    PubMed

    Wagner, Stefan; Schütz, Anja; Rademann, Jörg

    2015-06-15

    Phosphopeptide mimetics containing the 4-phosphonocarbonyl phenylalanine (pcF) as a photo-active phosphotyrosine isoster are developed as potent, light-switchable inhibitors of the protein tyrosine phosphatase PTP1B. The photo-active inhibitors 6-10 are derived from phosphopeptide substrates and are prepared from the suitably protected pcF building block 12 by Fmoc-based solid phase peptide synthesis. All pcF-containing peptides are moderate inhibitors of PTP1B with KI values between 10 and 50μM. Irradiation of the inhibitors at 365nm in the presence of the protein PTP1B amplify the inhibitory activity of pcF-peptides up to 120-fold, switching the KI values of the best inhibitors to the sub-micromolar range. Photo-activation of the inhibitors results in the formation of triplet intermediates of the benzoylphosphonate moiety, which deactivate PTP1B following an oxidative radical mechanism. Deactivation of PTP1B proceeds without covalent crosslinking of the protein target with the photo-switched inhibitors and can be reverted by subsequent addition of reducing agent dithiothreitol (DTT). PMID:25907367

  3. Furoxans (1, 2, 5 Oxadiazole-N-Oxides) as Novel NO Mimetic Neuroprotective and Procognitive Agents

    PubMed Central

    Schiefer, Isaac T.; VandeVrede, Lawren; Fa', Mauro; Arancio, Ottavio; Thatcher, Gregory R. J.

    2012-01-01

    Furoxans (1,2,5 oxadiazole-N-oxides) are thiol-bioactivated NO-mimetics that have not hitherto been studied in the CNS. Incorporation of varied substituents adjacent to the furoxan ring system led to modulation of reactivity towards bioactivation, studied by HPLC-MS/MS analysis of reaction products. Attenuated reactivity unmasked the cytoprotective actions of NO in contrast to the cytotoxic actions of higher NO fluxes reported previously for furoxans. Neuroprotection was observed in primary neuronal cell cultures following oxygen glucose deprivation (OGD). Neuroprotective activity was observed to correlate with thiol-dependent bioactivation to produce NO2-, but not with depletion of free thiol itself. Neuroprotection was abrogated upon co-treatment with a sGC inhibitor, ODQ, supporting activation of the NO/sGC/CREB signaling cascade by furoxans. Long-term potentiation (LTP), essential for learning and memory, has been shown to be potentiated by NO signaling, therefore, a peptidomimetic furoxan was tested in hippocampal slices treated with oligomeric amyloid-β peptide (Aβ) and was shown to restore synaptic function. The novel observation of furoxan activity of potential therapeutic use in the CNS warrants further studies. PMID:22429006

  4. Antimicrobial peptides

    PubMed Central

    2014-01-01

    With increasing antibiotics resistance, there is an urgent need for novel infection therapeutics. Since antimicrobial peptides provide opportunities for this, identification and optimization of such peptides have attracted much interest during recent years. Here, a brief overview of antimicrobial peptides is provided, with focus placed on how selected hydrophobic modifications of antimicrobial peptides can be employed to combat also more demanding pathogens, including multi-resistant strains, without conferring unacceptable toxicity. PMID:24758244

  5. Phage randomization in a charybdotoxin scaffold leads to CD4-mimetic recognition motifs that bind HIV-1 envelope through non-aromatic sequences.

    PubMed

    Li, C; Dowd, C S; Zhang, W; Chaiken, I M

    2001-06-01

    Binding of HIV-1 gp120 to T-cell receptor CD4 initiates conformational changes in the viral envelope that trigger viral entry into host cells. Phage epitope randomization of a beta-turn loop of a charybdotoxin-based miniprotein scaffold was used to identify peptides that can bind gp120 and block the gp120-CD4 interaction. We describe here the display of the charybdotoxin scaffold on the filamentous phage fUSE5, its use to construct a beta-turn library, and miniprotein sequences identified through library panning with immobilized Env gp120. Competition enzyme-linked immunosorbent assay (ELISA) identified high-frequency phage selectants for which specific gp120 binding was competed by sCD4. Several of these selectants contain hydrophobic residues in place of the Phe that occurs in the gp120-binding beta-turns of both CD4 and previously identified scorpion toxin CD4 mimetics. One of these selectants, denoted TXM[24GQTL27], contains GQTL in place of the CD4 beta-turn sequence 40QGSF43. TXM[24GQTL27] peptide was prepared using solid-phase chemical synthesis, its binding to gp120 demonstrated by optical biosensor kinetics analysis and its affinity for the CD4 binding site of gp120 confirmed by competition ELISA. The results demonstrate that aromatic-less loop-containing CD4 recognition mimetics can be formed with detectable envelope protein binding within a beta-turn of the charybdotoxin miniprotein scaffold. The results of this work establish a methodology for phage display of a charybdotoxin miniprotein scaffold and point to the potential value of phage-based epitope randomization of this miniprotein for identifying novel CD4 mimetics. The latter are potentially useful in deconvoluting structural determinants of CD4-HIV envelope recognition and possibly in designing antagonists of viral entry. PMID:11437954

  6. ApoA-I/HDL-C levels are inversely associated with abdominal aortic aneurysm progression.

    PubMed

    Burillo, Elena; Lindholt, Jes S; Molina-Sánchez, Pedro; Jorge, Immaculada; Martinez-Pinna, Roxana; Blanco-Colio, Luis Miguel; Tarin, Carlos; Torres-Fonseca, Monica Maria; Esteban, Margarita; Laustsen, Jesper; Ramos-Mozo, Priscilla; Calvo, Enrique; Lopez, Juan Antonio; Vega de Ceniga, Melina; Michel, Jean-Baptiste; Egido, Jesus; Andrés, Vicente; Vazquéz, Jesús; Meilhac, Olivier; Martin-Ventura, Jose Luis

    2015-06-01

    Abdominal aortic aneurysm (AAA) evolution is unpredictable, and there is no therapy except surgery for patients with an aortic size> 5 cm (large AAA). We aimed to identify new potential biomarkers that could facilitate prognosis and treatment of patients with AAA. A differential quantitative proteomic analysis of plasma proteins was performed in AAA patients at different stages of evolution [small AAA (aortic size=3-5 cm) vs large AAA] using iTRAQ labelling, high-throughput nano-LC-MS/MS and a novel multi-layered statistical model. Among the proteins identified, ApoA-I was decreased in patients with large AAA compared to those with small AAA. These results were validated by ELISA on plasma samples from small (n=90) and large AAA (n=26) patients (150± 3 vs 133± 5 mg/dl, respectively, p< 0.001). ApoA-I levels strongly correlated with HDL-Cholesterol (HDL-C) concentration (r=0.9, p< 0.001) and showed a negative correlation with aortic size (r=-0.4, p< 0.01) and thrombus volume (r=-0.3, p< 0.01), which remained significant after adjusting for traditional risk factors. In a prospective study, HDL-C independently predicted aneurysmal growth rate in multiple linear regression analysis (n=122, p=0.008) and was inversely associated with need for surgical repair (Adjusted hazard ratio: 0.18, 95 % confidence interval: 0.04-0.74, p=0.018). In a nation-wide Danish registry, we found lower mean HDL-C concentration in large AAA patients (n=6,560) compared with patients with aorto-iliac occlusive disease (n=23,496) (0.89± 2.99 vs 1.59± 5.74 mmol/l, p< 0.001). Finally, reduced mean aortic AAA diameter was observed in AngII-infused mice treated with ApoA-I mimetic peptide compared with saline-injected controls. In conclusion, ApoA-I/HDL-C systemic levels are negatively associated with AAA evolution. Therapies targeting HDL functionality could halt AAA formation. PMID:25789510

  7. Regulation of cancer stem-like cell differentiation by Smac mimetics

    PubMed Central

    Fulda, Simone

    2014-01-01

    Small-molecule antagonists of inhibitor of apoptosis (IAP) proteins such as Smac mimetics are considered promising cancer therapeutics through the engagement of cell death pathways. Recent evidence suggests that Smac mimetics perform additional nonapoptotic functions by initiating differentiation in cancer stem-like cells, opening new perspectives for their future clinical application. PMID:27308334

  8. Phylogenetic Codivergence Supports Coevolution of Mimetic Heliconius Butterflies

    PubMed Central

    Hoyal Cuthill, Jennifer; Charleston, Michael

    2012-01-01

    The unpalatable and warning-patterned butterflies Heliconius erato and Heliconius melpomene provide the best studied example of mutualistic Müllerian mimicry, thought–but rarely demonstrated–to promote coevolution. Some of the strongest available evidence for coevolution comes from phylogenetic codivergence, the parallel divergence of ecologically associated lineages. Early evolutionary reconstructions suggested codivergence between mimetic populations of H. erato and H. melpomene, and this was initially hailed as one of the most striking known cases of coevolution. However, subsequent molecular phylogenetic analyses found discrepancies in phylogenetic branching patterns and timing (topological and temporal incongruence) that argued against codivergence. We present the first explicit cophylogenetic test of codivergence between mimetic populations of H. erato and H. melpomene, and re-examine the timing of these radiations. We find statistically significant topological congruence between multilocus coalescent population phylogenies of H. erato and H. melpomene. Cophylogenetic historical reconstructions support repeated codivergence of mimetic populations, from the base of the sampled radiations. Pairwise distance correlation tests, based on our coalescent analyses plus recently published AFLP and wing colour pattern gene data, also suggest that the phylogenies of H. erato and H. melpomene show significant topological congruence. Divergence time estimates, based on a Bayesian coalescent model, suggest that the evolutionary radiations of H. erato and H. melpomene occurred over the same time period, and are compatible with a series of temporally congruent codivergence events. Our results suggest that differences in within-species genetic divergence are the result of a greater overall effective population size for H. erato relative to H. melpomene and do not imply incongruence in the timing of their phylogenetic radiations. Repeated codivergence between M

  9. Impact of Superoxide Dismutase Mimetic AEOL 10150 on the Endothelin System of Fischer 344 Rats

    PubMed Central

    Ganesh, Devi; Kumarathasan, Prem; Thomson, Errol M.; St-Germain, Carly; Blais, Erica; Crapo, James; Vincent, Renaud

    2016-01-01

    Endothelin-1 is a potent vasoconstrictor and mitogenic peptide involved in the regulation of vasomotor tone and maintenance of blood pressure. Oxidative stress activates the endothelin system, and is implicated in pulmonary and cardiovascular diseases including hypertension, congestive heart failure, and atherosclerosis. Superoxide dismutase mimetics designed with the aim of treating diseases that involve reactive oxygen species in their pathophysiology may exert a hypotensive effect, but effects on the endothelin system are unknown. Our objective was to determine the effect of the superoxide dismutase mimetic AEOL 10150 on the basal endothelin system in vivo. Male Fischer-344 rats were injected subcutaneously with 0, 2 or 5 mg/kg body weight of AEOL 10150 in saline. Plasma oxidative stress markers and endothelins (bigET-1, ET-1, ET-2, ET-3) as well as lung and heart endothelin/nitric oxide system gene expressions were measured using HPLC-Coularray, HPLC-Fluorescence and RT-PCR respectively. AEOL 10150 reduced (p<0.05) the circulating levels of isoprostane (-25%) and 3-nitrotyrosine (-50%) measured in plasma 2h and 24h after treatment, confirming delivery of a physiologically-relevant dose and the potent antioxidant activity of the drug. The reduction in markers of oxidative stress coincided with sustained 24h decrease (p<0.05) of plasma levels of ET-1 (-50%) and ET-3 (-10%). Expression of preproET-1 and endothelin converting enzyme-1 mRNA were not altered significantly in the lungs. However preproET-1 (not significant) and ECE-1 mRNA (p<0.05) were increased (10–25%) in the heart. Changes in the lungs included decrease (p<0.05) of mRNA for the ET-1 clearance receptor ETB and the vasoconstriction-signaling ETA receptor (-30%), and an early surge of inducible nitric oxide synthase expression followed by sustained decrease (-40% after 24 hours). The results indicate that interception of the endogenous physiological flux of reactive nitrogen species and reactive

  10. Therapeutic potential of a peptide targeting BCL-2 cell guardians in cancer.

    PubMed

    Adams, Jerry M

    2012-06-01

    A promising approach to cancer therapy is to elicit apoptosis with "BH3 mimetic" drugs, which target proteins of the BCL-2 family. As of yet, however, such drugs can target only certain BCL-2 family proteins. Hence, in this issue of the JCI, LaBelle et al. assess instead the therapeutic potential of a "stapled" BH3 peptide from the BIM protein, which inactivates all its prosurvival relatives. The peptide killed cultured hematologic tumor cells and abated growth of a leukemia xenograft, without perturbing the hematopoietic compartment. Hence, such peptides might eventually provide a new way to treat refractory leukemias. PMID:22622043

  11. Allylic Amines as Key Building Blocks in the Synthesis of (E)-Alkene Peptide Isosteres

    PubMed Central

    Skoda, Erin M.; Davis, Gary C.

    2012-01-01

    Nucleophilic imine additions with vinyl organometallics have developed into efficient, high yielding, and robust methodologies to generate structurally diverse allylic amines. We have used the hydrozirconation-transmetalation-imine addition protocol in the synthesis of allylic amine intermediates for peptide bond isosteres, phosphatase inhibitors, and mitochondria-targeted peptide mimetics. The gramicidin S-derived XJB-5-131 and JP4-039 and their analogs have been prepared on up to 160 g scale for preclinical studies. These (E)-alkene peptide isosteres adopt type II′ β-turn secondary structures and display impressive biological properties, including selective reactions with reactive oxygen species (ROS) and prevention of apoptosis. PMID:22323894

  12. Recombinant Elastin-Mimetic Biomaterials: Emerging Applications in Medicine

    PubMed Central

    Kim, Wookhyun; Chaikof, Elliot L.

    2010-01-01

    Biomaterials derived from protein-based block copolymers are increasingly investigated for potential application in medicine. In particular, recombinant elastin block copolymers provide significant opportunities to modulate material microstructure and can be processed in various forms, including particles, films, gels, and fiber networks. As a consequence, biological and mechanical responses of elastin-based biomaterials are tunable through precise control of block size and amino acid sequence. In this review, the synthesis of a set of elastin-mimetic triblock copolymers and their diverse processing methods for generating material platforms currently applied in medicine will be discussed. PMID:20441783

  13. Mimetic discretization of two-dimensional magnetic diffusion equations

    NASA Astrophysics Data System (ADS)

    Lipnikov, Konstantin; Reynolds, James; Nelson, Eric

    2013-08-01

    In case of non-constant resistivity, cylindrical coordinates, and highly distorted polygonal meshes, a consistent discretization of the magnetic diffusion equations requires new discretization tools based on a discrete vector and tensor calculus. We developed a new discretization method using the mimetic finite difference framework. It is second-order accurate on arbitrary polygonal meshes and a consistent calculation of the Joule heating is intrinsic within it. The second-order convergence rates in L2 and L1 norms were verified with numerical experiments.

  14. The mimetic repertoire of the spotted bowerbird Ptilonorhynchus maculatus

    NASA Astrophysics Data System (ADS)

    Kelley, Laura A.; Healy, Susan D.

    2011-06-01

    Although vocal mimicry in songbirds is well documented, little is known about the function of such mimicry. One possibility is that the mimic produces the vocalisations of predatory or aggressive species to deter potential predators or competitors. Alternatively, these sounds may be learned in error as a result of their acoustic properties such as structural simplicity. We determined the mimetic repertoires of a population of male spotted bowerbirds Ptilonorhynchus maculatus, a species that mimics predatory and aggressive species. Although male mimetic repertoires contained an overabundance of vocalisations produced by species that were generally aggressive, there was also a marked prevalence of mimicry of sounds that are associated with alarm such as predator calls, alarm calls and mobbing calls, irrespective of whether the species being mimicked was aggressive or not. We propose that it may be the alarming context in which these sounds are first heard that may lead both to their acquisition and to their later reproduction. We suggest that enhanced learning capability during acute stress may explain vocal mimicry in many species that mimic sounds associated with alarm.

  15. Road to Exercise Mimetics: Targeting Nuclear Receptors in Skeletal Muscle

    PubMed Central

    Fan, Weiwei; Atkins, Annette R; Yu, Ruth T.; Downes, Michael; Evans, Ronald M.

    2014-01-01

    Skeletal muscle comprises the largest organ in the human body and is the major site for energy expenditure. It exhibits remarkable plasticity in response to physiological stimuli such as exercise. Physical exercise remodels skeletal muscle and enhances its capability to burn calories, which has been shown to be beneficial for many clinical conditions including metabolic syndrome and cancer. Nuclear receptors (NRs) comprise a class of transcription factors found only in metazoans that regulate major biological processes such as reproduction, development, and metabolism. Recent studies have demonstrated crucial roles for NRs and their co-regulators in regulating skeletal muscle energy metabolism and exercise-induced muscle remodeling. While nothing can fully replace exercise, development of exercise mimetics that enhance or even substitute for the beneficial effects of physical exercise would be of great benefit. The unique property of NRs that allows modulation by endogenous or synthetic ligands makes them bona fide therapeutic targets. In this review, we present an overview of the current understanding of NRs and their co-regulators in skeletal muscle oxidative metabolism and summarize recent progress in the development of exercise mimetics that target NRs and their co-regulators. PMID:24280961

  16. Mimetic butterflies support Wallace's model of sexual dimorphism.

    PubMed

    Kunte, Krushnamegh

    2008-07-22

    Theoretical and empirical observations generally support Darwin's view that sexual dimorphism evolves due to sexual selection on, and deviation in, exaggerated male traits. Wallace presented a radical alternative, which is largely untested, that sexual dimorphism results from naturally selected deviation in protective female coloration. This leads to the prediction that deviation in female rather than male phenotype causes sexual dimorphism. Here I test Wallace's model of sexual dimorphism by tracing the evolutionary history of Batesian mimicry-an example of naturally selected protective coloration-on a molecular phylogeny of Papilio butterflies. I show that sexual dimorphism in Papilio is significantly correlated with both female-limited Batesian mimicry, where females are mimetic and males are non-mimetic, and with the deviation of female wing colour patterns from the ancestral patterns conserved in males. Thus, Wallace's model largely explains sexual dimorphism in Papilio. This finding, along with indirect support from recent studies on birds and lizards, suggests that Wallace's model may be more widely useful in explaining sexual dimorphism. These results also highlight the contribution of naturally selected female traits in driving phenotypic divergence between species, instead of merely facilitating the divergence in male sexual traits as described by Darwin's model. PMID:18426753

  17. Small-molecule SMAC mimetics as new cancer therapeutics.

    PubMed

    Bai, Longchuan; Smith, David C; Wang, Shaomeng

    2014-10-01

    Apoptosis is a tightly regulated cellular process and faulty regulation of apoptosis is a hallmark of human cancers. Targeting key apoptosis regulators with the goal to restore apoptosis in tumor cells has been pursued as a new cancer therapeutic strategy. XIAP, cIAP1, and cIAP2, members of inhibitor of apoptosis (IAP) proteins, are critical regulators of cell death and survival and are attractive targets for new cancer therapy. The SMAC/DIABLO protein is an endogenous antagonist of XIAP, cIAP1, and cIAP2. In the last decade, intense research efforts have resulted in the design and development of several small-molecule SMAC mimetics now in clinical trials for cancer treatment. In this review, we will discuss the roles of XIAP, cIAP1, and cIAP2 in regulation of cell death and survival, and the design and development of small-molecule SMAC mimetics as novel cancer treatments. PMID:24841289

  18. Synthesis and Characterization of Elastin-Mimetic Hybrid Polymers with Multiblock, Alternating Molecular Architecture and Elastomeric Properties

    PubMed Central

    Grieshaber, Sarah E.; Farran, Alexandra J. E.; Lin-Gibson, Sheng; Kiick, Kristi L.; Jia, Xinqiao

    2009-01-01

    We are interested in developing elastin–mimetic hybrid polymers (EMHPs) that capture the multiblock molecular architecture of tropoelastin as well as the remarkable elasticity of mature elastin. In this study, multiblock EMHPs containing flexible synthetic segments based on poly(ethylene glycol) (PEG) alternating with alanine-rich, lysine-containing peptides were synthesized by step-growth polymerization using α,ω-azido-PEG and alkyne-terminated AKA3KA (K = lysine, A = alanine) peptide, employing orthogonal click chemistry. The resulting EMHPs contain an estimated three to five repeats of PEG and AKA3KA and have an average molecular weight of 34 kDa. While the peptide alone exhibited α-helical structures at high pH, the fractional helicity for EMHPs was reduced. Covalent cross-linking of EMHPs with hexamethylene diisocyanate (HMDI) through the lysine residue in the peptide domain afforded an elastomeric hydrogel (xEMHP) with a compressive modulus of 0.12 MPa when hydrated. The mechanical properties of xEMHP are comparable to a commercial polyurethane elastomer (Tecoflex SG80A) under the same conditions. In vitro toxicity studies showed that while the soluble EMHPs inhibited the growth of primary porcine vocal fold fibroblasts (PVFFs) at concentrations ≥0.2 mg/mL, the cross-linked hybrid elastomers did not leach out any toxic reagents and allowed PVFFs to grow and proliferate normally. The hybrid and modular approach provides a new strategy for developing elastomeric scaffolds for tissue engineering. PMID:19763157

  19. Single-spanning membrane protein insertion in membrane mimetic systems: role and localization of aromatic residues.

    PubMed

    Coïc, Yves-Marie; Vincent, Michel; Gallay, Jacques; Baleux, Françoise; Mousson, Florence; Beswick, Veronica; Neumann, Jean-Michel; de Foresta, Béatrice

    2005-12-01

    Membrane protein insertion in the lipid bilayer is determining for their activity and is governed by various factors such as specific sequence motifs or key amino-acids. A detailed fluorescence study of such factors is exemplified with PMP1, a small (38 residues) single-membrane span protein that regulates the plasma membrane H(+)-ATPase in yeast and specifically interacts with phosphatidylserines. Such interactions may stabilize raft domains that have been shown to contain H(+)-ATPase. Previous NMR studies of various fragments have focused on the critical role of interfacial residues in the PMP1 structure and intermolecular interactions. The C-terminal domain contains a terminal Phe (F38), a single Trp (W28) and a single Tyr (Y25) that may act together to anchor the protein in the membrane. In order to describe the location and dynamics of W28 and the influence of Y25 on protein insertion within membrane, we carried out a detailed steady-state and time-resolved fluorescence study of the synthetic G13-F38 fragment and its Tyr-less mutant, Y25L in various membrane mimetic systems. Detergent micelles are conveniently used for this purpose. We used dodecylphosphocholine (DPC) in order to compare with and complement previous NMR results. In addition, dodecylmaltoside (DM) was used so that we could apply our recently described new quenching method by two brominated analogs of DM (de Foresta et al. 2002, Eur. Biophys. J. 31:185-97). In both systems, and in the presence and absence of Y25, W28 was shown to be located below but close to the polar headgroup region, as shown by its maximum emission wavelengths (lambda(max)), curves for the quenching of Trp by the brominated analogs of DM and bimolecular constants for quenching (k(q)) by acrylamide. Results were interpreted by comparison with calibration data obtained with fluorescent model peptides. Time-resolved anisotropy measurements were consistent with PMP1 fragment immobilization within peptide-detergent complexes. We

  20. Cell Penetrating Elastin-like Polypeptides for Therapeutic Peptide Delivery

    PubMed Central

    Bidwell, Gene L.; Raucher, Drazen

    2010-01-01

    Current treatment of solid tumors is limited by side effects that result from the nonspecific delivery of drugs to the tumor site. Alternative targeted therapeutic approaches for localized tumors would significantly reduce systemic toxicity. Peptide therapeutics are a promising new strategy for targeted cancer therapy because of the ease of peptide design and the specificity of peptides for their intracellular molecular targets. However, the utility of peptides is limited by their poor pharmacokinetic parameters and poor tissue and cellular membrane permeability in vivo. This review article summarizes the development of elastin-like polypeptide (ELP) as a potential carrier for thermally targeted delivery of therapeutic peptides (TP), and the use of cell penetrating peptides (CPP) to enhance the intracellular delivery of the ELP-fused TPs. CPP-fused ELPs have been used to deliver a peptide inhibitor of c-Myc function and a peptide mimetic of p21 in several cancer models in vitro, and both polypeptides are currently yielding promising results in in vivo models of breast and brain cancer. PMID:20478348

  1. Ionic supramolecular bonds preserve mechanical properties and enable synergetic performance at high humidity in water-borne, self-assembled nacre-mimetics

    NASA Astrophysics Data System (ADS)

    Das, Paramita; Walther, Andreas

    2013-09-01

    Although tremendous effort has been focused on enhancing the mechanical properties of nacre-mimetic materials, conservation of high stiffness and strength against hydration-induced decay of mechanical properties at high humidity remains a fundamental challenge in such water-borne high-performance materials. Herein, we demonstrate that ionic supramolecular bonds, introduced by infiltration of divalent Cu2+ ions, allow efficient stabilization of the mechanical properties of self-assembled water-borne nacre-mimetics based on sustainable sodium carboxymethylcellulose (Na+CMC) and natural sodium montmorillonite nanoclay (Na+MTM) against high humidity (95% RH). The mechanical properties in the highly hydrated state (Young's modulus up to 13.5 GPa and tensile strength up to 125 MPa) are in fact comparable to a range of non-crosslinked nacre-mimetic materials in the dry state. Moreover, the Cu2+-treated nacre-inspired materials display synergetic mechanical properties as found in a simultaneous improvement of stiffness, strength and toughness, as compared to the pristine material. Significant inelastic deformation takes place considering the highly reinforced state. This contrasts the typical behaviour of tight, covalent crosslinks and is suggested to originate from a sacrificial, dynamic breakage and rebinding of transient supramolecular ionic bonds. Considering easy access to a large range of ionic interactions and alteration of counter-ion charge via external stimuli, we foresee responsive and adaptive mechanical properties in highly reinforced and stiff bio-inspired bulk nanocomposites and in other bio-inspired materials, e.g. nanocellulose papers and peptide-based materials.Although tremendous effort has been focused on enhancing the mechanical properties of nacre-mimetic materials, conservation of high stiffness and strength against hydration-induced decay of mechanical properties at high humidity remains a fundamental challenge in such water-borne high

  2. Possible interaction of quinolone antibiotics with peptide transporter 1 in oral absorption of peptide-mimetic drugs.

    PubMed

    Arakawa, Hiroshi; Kamioka, Hiroki; Kanagawa, Masahiko; Hatano, Yasuko; Idota, Yoko; Yano, Kentaro; Morimoto, Kaori; Ogihara, Takuo

    2016-01-01

    The study investigated whether quinolone antibiotics inhibit the PEPT1-mediated uptake of its substrates. Among the quinolones examined, lomefloxacin, moxifloxacin (MFLX) and purlifloxacin significantly inhibited the uptake of PEPT1 substrate phenylalanine-Ψ(CN-S)-alanine (Phe-Ψ-Ala) in HeLa/PEPT1 cells to 31.6 ± 1.3%, 27.6 ± 2.9%, 36.8 ± 2.2% and 32.6 ± 1.4%, respectively. Further examination showed that MFLX was an uncompetitive inhibitor, with an IC50 value of 4.29 ± 1.29 mm. In addition, MFLX significantly decreased the cephalexin and valacyclovir uptake in HeLa/PEPT1 cells. In an in vivo study in rats, the maximum plasma concentration (C(max)) of orally administered Phe-Ψ-Ala was significantly decreased in the presence of MFLX (171 ± 1 ng/ml) compared with that in its absence (244 ± 9 ng/ml). The area under the concentration-time curve (AUC) of orally administered Phe-Ψ-Ala in the presence of MFLX (338 ± 50 ng/ml · h) tended to decrease compared with that in its absence (399 ± 75 ng/ml · h). The oral bioavailability of Phe-Ψ-Ala in the presence and absence of MFLX was 41.7 ± 6.2% and 49.2 ± 9.2%, respectively. The results indicate that administration of quinolone antibiotics concomitantly with PEPT1 substrate drugs may potentially result in drug-drug interaction. PMID:26590007

  3. A multilevel multiscale mimetic method for an anisotropic infiltration problem

    SciTech Connect

    Lipnikov, Konstantin; Moulton, David; Svyatskiy, Daniil

    2009-01-01

    Modeling of multiphase flow and transport in highly heterogeneous porous media must capture a broad range of coupled spatial and temporal scales. Recently, a hierarchical approach dubbed the Multilevel Multiscale Mimetic (M3) method, was developed to simulate two-phase flow in porous media. The M{sup 3} method is locally mass conserving at all levels in its hierarchy, it supports unstructured polygonal grids and full tensor permeabilities, and it can achieve large coarsening factors. In this work we consider infiltration of water into a two-dimensional layered medium. The grid is aligned with the layers but not the coordinate axes. We demonstrate that with an efficient temporal updating strategy for the coarsening parameters, fine-scale accuracy of prominent features in the flow is maintained by the M{sup 3} method.

  4. Towards protein-based viral mimetics for cancer therapies.

    PubMed

    Unzueta, Ugutz; Céspedes, María Virtudes; Vázquez, Esther; Ferrer-Miralles, Neus; Mangues, Ramón; Villaverde, Antonio

    2015-05-01

    High resistance and recurrence rates, together with elevated drug clearance, compel the use of maximum-tolerated drug doses in cancer therapy, resulting in high-grade toxicities and limited clinical applicability. Promoting active drug accumulation in tumor tissues would minimize such issues and improve therapeutic outcomes. A new class of therapeutic drugs suitable for the task has emerged based on the concept of virus-mimetic nanocarriers, or 'artificial viruses'. Among the spectrum of materials under exploration in nanocarrier research, proteins offer unparalleled structural and functional versatility for designing virus-like molecular vehicles. By exhibiting 'smart' functions and biomimetic traits, protein-based nanocarriers will be a step ahead of the conventional drug-protein conjugates already in the clinic in ensuring efficient delivery of passenger antitumor drugs. PMID:25805413

  5. No-mimetic furoxans: arylsulphonylfuroxans and related compounds.

    PubMed

    Ferioli, R; Fazzini, A; Folco, G C; Fruttero, R; Calvino, R; Gasco, A; Bongrani, S; Civelli, M

    1993-01-01

    A new class of methylfuroxans and methylfurazans arylthio, arylsulphinyl and arylsulphonyl substituted, characterized by vasodilating and antiaggregatory properties, is described. Vasodilating activity, tested on rabbit aortic rings percontracted with 1 microM noradrenaline, is enhanced by N-oxidation of the furazan ring and is maximized by increase of the sulphur atom oxidation level. Compounds 4-methyl-3-(p-methoxyphenylsulphonyl) furoxan 6c, 3-phenyl-4-phenylsulphonylfuroxan 10, 4-phenyl-3-phenylsulphonylfuroxan 11 and 3,4-bis(phenyl-sulphonyl)furoxan 12 (EC50 values ranging between 0.055-1.07 microM), seem to be promising since they show the highest potency as well as maximal efficacy, causing complete reversal of noradrenaline induced contraction. The structure-activity relationship, observed in the platelet aggregation test, is substantially similar to that reported for the vasodilating activity, in line with the general profile of these drugs as putative NO-mimetic derivatives. PMID:8108310

  6. Ancient homology underlies adaptive mimetic diversity across butterflies.

    PubMed

    Gallant, Jason R; Imhoff, Vance E; Martin, Arnaud; Savage, Wesley K; Chamberlain, Nicola L; Pote, Ben L; Peterson, Chelsea; Smith, Gabriella E; Evans, Benjamin; Reed, Robert D; Kronforst, Marcus R; Mullen, Sean P

    2014-01-01

    Convergent evolution provides a rare, natural experiment with which to test the predictability of adaptation at the molecular level. Little is known about the molecular basis of convergence over macro-evolutionary timescales. Here we use a combination of positional cloning, population genomic resequencing, association mapping and developmental data to demonstrate that positionally orthologous nucleotide variants in the upstream region of the same gene, WntA, are responsible for parallel mimetic variation in two butterfly lineages that diverged >65 million years ago. Furthermore, characterization of spatial patterns of WntA expression during development suggests that alternative regulatory mechanisms underlie wing pattern variation in each system. Taken together, our results reveal a strikingly predictable molecular basis for phenotypic convergence over deep evolutionary time. PMID:25198507

  7. Type I Collagen and Collagen Mimetics as Angiogenesis Promoting Superpolymers

    SciTech Connect

    Twardowski, T.; Fertala, A.; Orgel, J.P.R.O.; San Antonio, J.D.

    2008-07-18

    Angiogenesis, the development of blood vessels from the pre-existing vasculature, is a key component of embryogenesis and tissue regeneration. Angiogenesis also drives pathologies such as tumor growth and metastasis, and hemangioma development in newborns. On the other hand, promotion of angiogenesis is needed in tissues with vascular insufficiencies, and in bioengineering, to endow tissue substitutes with appropriate microvasculatures. Therefore, much research has focused on defining mechanisms of angiogenesis, and identifying pro- and anti-angiogenic molecules. Type I collagen, the most abundant protein in humans, potently stimulates angiogenesis in vitro and in vivo. Crucial to its angiogenic activity appears to be ligation and possibly clustering of endothelial cell (EC) surface {alpha}1{beta}1/{alpha}2{beta}1 integrin receptors by the GFPGER502-507 sequence of the collagen fibril. However, additional aspects of collagen structure and function that may modulate its angiogenic properties are discussed. Moreover, type I collagen and fibrin, another angiogenic polymer, share several structural features. These observations suggest strategies for creating 'angiogenic superpolymers', including: modifying type I collagen to influence its biological half-life, immunogenicity, and integrin binding capacity; genetically engineering fibrillar collagens to include additional integrin binding sites or angiogenic determinants, and remove unnecessary or deleterious sequences without compromising fibril integrity; and exploring the suitability of poly(ortho ester), PEG-lysine copolymer, tubulin, and cholesteric cuticle as collagen mimetics, and suggesting means of modifying them to display ideal angiogenic properties. The collagenous and collagen mimetic angiogenic superpolymers described here may someday prove useful for many applications in tissue engineering and human medicine.

  8. A non-linear constrained optimization technique for the mimetic finite difference method

    SciTech Connect

    Manzini, Gianmarco; Svyatskiy, Daniil; Bertolazzi, Enrico; Frego, Marco

    2014-09-30

    This is a strategy for the construction of monotone schemes in the framework of the mimetic finite difference method for the approximation of diffusion problems on unstructured polygonal and polyhedral meshes.

  9. Photochemical solar energy conversion utilizing semiconductors localized in membrane-mimetic systems

    SciTech Connect

    Fendler, J.H.

    1991-08-31

    Extending the frontiers of colloidal photochemistry and colloidal electrochemistry to solar photochemistry research had been the main objective of this research. More specific objectives of this proposal include the examination of semiconductor-particle-mediated photoelectron transfer and photoelectric effects in different membrane mimetic systems. Emphasis had been placed on developing bilayer lipid membranes and Langmuir-Blodgett films as new membrane-mimetic systems, as well as on the characterization and utilization of these systems.

  10. Smac mimetics increase cancer cell response to chemotherapeutics in a TNF-α-dependent manner

    PubMed Central

    Probst, BL; Liu, L; Ramesh, V; Li, L; Sun, H; Minna, JD; Wang, L

    2011-01-01

    Second mitochondria-derived activator of caspase (Smac) is a mitochondrial protein released into the cytosol during apoptosis. Smac mimetics have recently been touted as a novel therapeutic to induce apoptosis in cancer cells. The ability of Smac mimetics to induce apoptosis in vitro has been shown to be dependent upon both XIAP neutralization and cancer cell autocrine tumor necrosis factor-α (TNF-α) production. In this study we provide new evidence for the utility of Smac mimetics in combination with conventional chemotherapy agents to exacerbate caspase activation and induce cancer cell death. Furthermore, we find that the combination effect is because of a multifaceted mechanism involving both inhibition of cell proliferation by the chemotherapy agents and an enhanced autocrine TNF-α feedback loop by the Smac mimetic/chemotherapy agent combination. Surprisingly, although genotoxic agents typically induce apoptosis through the mitochondrial intrinsic pathway, we show that this synergism is mediated through a TNF-α/RIP1-dependent pathway, leading to activation of the extrinsic apoptotic pathway. Finally, we report that autocrine TNF-α contributes to Smac mimetic-induced tumor regression as a single agent or in combination with chemotherapeutics in xenograft mouse models. Collectively, we provide mechanistic and applicable data to support translational studies in the use of a Smac mimetic/chemotherapy antineoplasm modality. PMID:20431601

  11. Mimetic Divergence and the Speciation Continuum in the Mimic Poison Frog Ranitomeya imitator.

    PubMed

    Twomey, Evan; Vestergaard, Jacob S; Venegas, Pablo J; Summers, Kyle

    2016-02-01

    While divergent ecological adaptation can drive speciation, understanding the factors that facilitate or constrain this process remains a major goal in speciation research. Here, we study two mimetic transition zones in the poison frog Ranitomeya imitator, a species that has undergone a Müllerian mimetic radiation to establish four morphs in Peru. We find that mimetic morphs are strongly phenotypically differentiated, producing geographic clines with varying widths. However, distinct morphs show little neutral genetic divergence, and landscape genetic analyses implicate isolation by distance as the primary determinant of among-population genetic differentiation. Mate choice experiments suggest random mating at the transition zones, although certain allopatric populations show a preference for their own morph. We present evidence that this preference may be mediated by color pattern specifically. These results contrast with an earlier study of a third transition zone, in which a mimetic shift was associated with reproductive isolation. Overall, our results suggest that the three known mimetic transition zones in R. imitator reflect a speciation continuum, which we have characterized at the geographic, phenotypic, behavioral, and genetic levels. We discuss possible explanations for variable progress toward speciation, suggesting that multifarious selection on both mimetic color pattern and body size may be responsible for generating reproductive isolation. PMID:26807748

  12. Peptide identification

    DOEpatents

    Jarman, Kristin H [Richland, WA; Cannon, William R [Richland, WA; Jarman, Kenneth D [Richland, WA; Heredia-Langner, Alejandro [Richland, WA

    2011-07-12

    Peptides are identified from a list of candidates using collision-induced dissociation tandem mass spectrometry data. A probabilistic model for the occurrence of spectral peaks corresponding to frequently observed partial peptide fragment ions is applied. As part of the identification procedure, a probability score is produced that indicates the likelihood of any given candidate being the correct match. The statistical significance of the score is known without necessarily having reference to the actual identity of the peptide. In one form of the invention, a genetic algorithm is applied to candidate peptides using an objective function that takes into account the number of shifted peaks appearing in the candidate spectrum relative to the test spectrum.

  13. Synthetic Amphipathic Helical Peptides Targeting CD36 Attenuate Lipopolysaccharide-Induced Inflammation and Acute Lung Injury.

    PubMed

    Bocharov, Alexander V; Wu, Tinghuai; Baranova, Irina N; Birukova, Anna A; Sviridov, Denis; Vishnyakova, Tatyana G; Remaley, Alan T; Eggerman, Thomas L; Patterson, Amy P; Birukov, Konstantin G

    2016-07-15

    Synthetic amphipathic helical peptides (SAHPs) designed as apolipoprotein A-I mimetics are known to bind to class B scavenger receptors (SR-Bs), SR-BI, SR-BII, and CD36, receptors that mediate lipid transport and facilitate pathogen recognition. In this study, we evaluated SAHPs, selected for targeting human CD36, by their ability to attenuate LPS-induced inflammation, endothelial barrier dysfunction, and acute lung injury (ALI). L37pA, which targets CD36 and SR-BI equally, inhibited LPS-induced IL-8 secretion and barrier dysfunction in cultured endothelial cells while reducing lung neutrophil infiltration by 40% in a mouse model of LPS-induced ALI. A panel of 20 SAHPs was tested in HEK293 cell lines stably transfected with various SR-Bs to identify SAHPs with preferential selectivity toward CD36. Among several SAHPs targeting both SR-BI/BII and CD36 receptors, ELK-B acted predominantly through CD36. Compared with L37pA, 5A, and ELK SAHPs, ELK-B was most effective in reducing the pulmonary barrier dysfunction, neutrophil migration into the lung, and lung inflammation induced by LPS. We conclude that SAHPs with relative selectivity toward CD36 are more potent at inhibiting acute pulmonary inflammation and dysfunction. These data indicate that therapeutic strategies using SAHPs targeting CD36, but not necessarily mimicking all apolipoprotein A-I functions, may be considered a possible new treatment approach for inflammation-induced ALI and pulmonary edema. PMID:27316682

  14. Motif mimetic of epsin perturbs tumor growth and metastasis

    PubMed Central

    Dong, Yunzhou; Wu, Hao; Rahman, H.N. Ashiqur; Liu, Yanjun; Pasula, Satish; Tessneer, Kandice L.; Cai, Xiaofeng; Liu, Xiaolei; Chang, Baojun; McManus, John; Hahn, Scott; Dong, Jiali; Brophy, Megan L.; Yu, Lili; Song, Kai; Silasi-Mansat, Robert; Saunders, Debra; Njoku, Charity; Song, Hoogeun; Mehta-D’Souza, Padmaja; Towner, Rheal; Lupu, Florea; McEver, Rodger P.; Xia, Lijun; Boerboom, Derek; Srinivasan, R. Sathish; Chen, Hong

    2015-01-01

    Tumor angiogenesis is critical for cancer progression. In multiple murine models, endothelium-specific epsin deficiency abrogates tumor progression by shifting the balance of VEGFR2 signaling toward uncontrolled tumor angiogenesis, resulting in dysfunctional tumor vasculature. Here, we designed a tumor endothelium–targeting chimeric peptide (UPI) for the purpose of inhibiting endogenous tumor endothelial epsins by competitively binding activated VEGFR2. We determined that the UPI peptide specifically targets tumor endothelial VEGFR2 through an unconventional binding mechanism that is driven by unique residues present only in the epsin ubiquitin–interacting motif (UIM) and the VEGFR2 kinase domain. In murine models of neoangiogenesis, UPI peptide increased VEGF-driven angiogenesis and neovascularization but spared quiescent vascular beds. Further, in tumor-bearing mice, UPI peptide markedly impaired functional tumor angiogenesis, tumor growth, and metastasis, resulting in a notable increase in survival. Coadministration of UPI peptide with cytotoxic chemotherapeutics further sustained tumor inhibition. Equipped with localized tumor endothelium–specific targeting, our UPI peptide provides potential for an effective and alternative cancer therapy. PMID:26571402

  15. A continued saga of Boc5, the first non-peptidic glucagon-like peptide-1 receptor agonist with in vivo activities

    PubMed Central

    He, Min; Guan, Ni; Gao, Wei-wei; Liu, Qing; Wu, Xiao-yan; Ma, Da-wei; Zhong, Da-fang; Ge, Guang-bo; Li, Chuan; Chen, Xiao-yan; Yang, Ling; Liao, Jia-yu; Wang, Ming-wei

    2012-01-01

    Glucagon-like peptide-1 (GLP-1)-based therapy presents a promising option for treating type 2 diabetes. However, there are several limitations relative to the peptidic GLP-1 mimetics currently on the market or under development. This concern has led to a continued interest in the search for non-peptidic agonists for GLP-1 receptor (GLP-1R). Here, we briefly review the discovery, characterization and current status of a novel class of cyclobutane-derivative-based non-peptidic agonists for GLP-1R, including Boc5 and its newly discovered analogue WB4–24. Although the oral bioavailability of such compounds still poses great challenges, the progress made so far encourages us to identify a truly 'druggable' small molecule agonist for GLP-1R. PMID:22301855

  16. Cysteine-containing peptides having antioxidant properties

    DOEpatents

    Bielicki, John K.

    2009-10-13

    Cysteine containing amphipathic alpha helices of the exchangeable apolipoproteins, as exemplified by apolipoprotein (apo) A-I.sub.Milano (R173C) and apoA-I.sub.Paris, (R151C) were found to exhibit potent antioxidant activity on phospholipid surfaces. The addition of a free thiol, at the hydrophobic/hydrophilic interface of an amphipathic alpha helix of synthetic peptides that mimic HDL-related proteins, imparts a unique antioxidant activity to these peptides which inhibits lipid peroxidation and protects phospholipids from water-soluble free radical initiators. These peptides can be used as therapeutic agents to combat cardiovascular disease, ischemia, bone disease and other inflammatory related diseases.

  17. Cysteine-containing peptides having antioxidant properties

    DOEpatents

    Bielicki, John K.

    2008-10-21

    Cysteine containing amphipathic alpha helices of the exchangeable apolipoproteins, as exemplified by apolipoprotein (apo) A-I.sub.Milano (R173C) and apoA-I.sub.Paris, (R151C) were found to exhibit potent antioxidant activity on phospholipid surfaces. The addition of a free thiol, at the hydrophobic/hydrophilic interface of an amphipathic alpha helix of synthetic peptides that mimic HDL-related proteins, imparts a unique antioxidant activity to these peptides which inhibits lipid peroxidation and protects phospholipids from water-soluble free radical initiators. These peptides can be used as therapeutic agents to combat cardiovascular disease, ischemia, bone disease and other inflammatory related diseases.

  18. Structural and Functional Studies of Peptide-Carbohydrate Mimicry

    NASA Astrophysics Data System (ADS)

    Johnson, Margaret A.; Pinto, B. Mario

    Certain peptides act as molecular mimics of carbohydrates in that they are specifically recognized by carbohydrate-binding proteins. Peptides that bind to anti-carbohydrate antibodies, carbohydrate-processing enzymes, and lectins have been identified. These peptides are potentially useful as vaccines and therapeutics; for example, immunologically functional peptide molecular mimics (mimotopes) can strengthen or modify immune responses induced by carbohydrate antigens. However, peptides that bind specifically to carbohydrate-binding proteins may not necessarily show the corresponding biological activity, and further selection based on biochemical studies is always required. The degree of structural mimicry required to generate the desired biological activity is therefore an interesting question. This review will discuss recent structural studies of peptide-carbohydrate mimicry employing NMR spectroscopy, X-ray crystallography, and molecular modeling, as well as relevant biochemical data. These studies provide insights into the basis of mimicry at the molecular level. Comparisons with other carbohydrate-mimetic compounds, namely proteins and glycopeptides, will be drawn. Finally, implications for the design of new therapeutic compounds will also be presented.

  19. An amphipathic alpha-helical peptide from apolipoprotein A1 stabilizes protein polymer vesicles.

    PubMed

    Pastuszka, Martha K; Wang, Xiangdong; Lock, Lye Lin; Janib, Siti Mohd; Cui, Honggang; DeLeve, Laurie D; MacKay, J Andrew

    2014-10-10

    L4F, an alpha helical peptide inspired by the lipid-binding domain of the ApoA1 protein, has potential applications in the reduction of inflammation involved with cardiovascular disease as well as an antioxidant effect that inhibits liver fibrosis. In addition to its biological activity, amphipathic peptides such as L4F are likely candidates to direct the molecular assembly of peptide nanostructures. Here we describe the stabilization of the amphipathic L4F peptide through fusion to a high molecular weight protein polymer. Comprised of multiple pentameric repeats, elastin-like polypeptides (ELPs) are biodegradable protein polymers inspired from the human gene for tropoelastin. Dynamic light scattering confirmed that the fusion peptide forms nanoparticles with a hydrodynamic radius of approximately 50nm, which is unexpectedly above that observed for the free ELP (~5.1nm). To further investigate their morphology, conventional and cryogenic transmission electron microscopy were used to reveal that they are unilamellar vesicles. On average, these vesicles are 49nm in radius with lamellae 8nm in thickness. To evaluate their therapeutic potential, the L4F nanoparticles were incubated with hepatic stellate cells. Stellate cell activation leads to hepatic fibrosis; furthermore, their activation is suppressed by anti-oxidant activity of ApoA1 mimetic peptides. Consistent with this observation, L4F nanoparticles were found to suppress hepatic stellate cell activation in vitro. To evaluate the in vivo potential for these nanostructures, their plasma pharmacokinetics were evaluated in rats. Despite the assembly of nanostructures, both free L4F and L4F nanoparticles exhibited similar half-lives of approximately 1h in plasma. This is the first study reporting the stabilization of peptide-based vesicles using ApoA1 mimetic peptides fused to a protein polymer; furthermore, this platform for peptide-vesicle assembly may have utility in the design of biodegradable nanostructures

  20. Cerebral Response to Peripheral Challenge with a Viral Mimetic.

    PubMed

    Konat, Gregory

    2016-02-01

    It has been well established that peripheral inflammation resulting from microbial infections profoundly alters brain function. This review focuses on experimental systems that model cerebral effects of peripheral viral challenge. The most common models employ the induction of the acute phase response via intraperitoneal injection of a viral mimetic, polyinosinic-polycytidylic acid (PIC). The ensuing transient surge of blood-borne inflammatory mediators induces a "mirror" inflammatory response in the brain characterized by the upregulated expression of a plethora of genes encoding cytokines, chemokines and other inflammatory/stress proteins. These inflammatory mediators modify the activity of neuronal networks leading to a constellation of behavioral traits collectively categorized as the sickness behavior. Sickness behavior is an important protective response of the host that has evolved to enhance survival and limit the spread of infections within a population. However, a growing body of clinical data indicates that the activation of inflammatory pathways in the brain may constitute a serious comorbidity factor for neuropathological conditions. Such comorbidity has been demonstrated using the PIC paradigm in experimental models of Alzheimer's disease, prion disease and seizures. Also, prenatal or perinatal PIC challenge has been shown to disrupt normal cerebral development of the offspring resulting in phenotypes consistent with neuropsychiatric disorders, such as schizophrenia and autism. Remarkably, recent studies indicate that mild peripheral PIC challenge may be neuroprotective in stroke. Altogether, the PIC challenge paradigm represents a unique heuristic model to elucidate the immune-to-brain communication pathways and to explore preventive strategies for neuropathological disorders. PMID:26526143

  1. A manganese porphyrin superoxide dismutase mimetic enhances tumor radioresponsiveness

    SciTech Connect

    Moeller, Benjamin J.; Batinic-Haberle, Ines; Spasojevic, Ivan; Rabbani, Zahid N.; Anscher, Mitchell S.; Vujaskovic, Zeljko; Dewhirst, Mark W. D.V.M. . E-mail: dewhirst@radonc.duke.edu

    2005-10-01

    Purpose: To determine the effect of the superoxide dismutase mimetic Mn(III) tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP{sup 5+}) on tumor radioresponsiveness. Methods and Materials: Various rodent tumor (4T1, R3230, B16) and endothelial (SVEC) cell lines were exposed to MnTE-2-PyP{sup 5+} and assayed for viability and radiosensitivity in vitro. Next, tumors were treated with radiation and MnTE-2-PyP{sup 5+} in vivo, and the effects on tumor growth and vascularity were monitored. Results: In vitro, MnTE-2-PyP{sup 5+} was not significantly cytotoxic. However, at concentrations as low as 2 {mu}mol/L it caused 100% inhibition of secretion by tumor cells of cytokines protective of irradiated endothelial cells. In vivo, combined treatment with radiation and MnTE-2-PyP{sup 5+} achieved synergistic tumor devascularization, reducing vascular density by 78.7% within 72 h of radiotherapy (p < 0.05 vs. radiation or drug alone). Co-treatment of tumors also resulted in synergistic antitumor effects, extending tumor growth delay by 9 days (p < 0.01). Conclusions: These studies support the conclusion that MnTE-2-PyP{sup 5+}, which has been shown to protect normal tissues from radiation injury, can also improve tumor control through augmenting radiation-induced damage to the tumor vasculature.

  2. Bio-mimetic optical sensor for structural deflection measurement

    NASA Astrophysics Data System (ADS)

    Frost, Susan A.; Wright, Cameron H. G.; Streeter, Robert W.; Khan, Md. A.; Barrett, Steven F.

    2014-03-01

    Reducing the environmental impact of aviation is a primary goal of NASA aeronautics research. One approach to achieve this goal is to build lighter weight aircraft, which presents complex challenges due to a corresponding increase in structural flexibility. Wing flexibility can adversely affect aircraft performance from the perspective of aerodynamic efficiency and safety. Knowledge of the wing position during flight can aid active control methods designed to mitigate problems due to increased wing flexibility. Current approaches to measuring wing deflection, including strain measurement devices, accelerometers, or GPS solutions, and new technologies such as fiber optic strain sensors, have limitations for their practical application to flexible aircraft control. Hence, it was proposed to use a bio-mimetic optical sensor based on the fly-eye to track wing deflection in real-time. The fly-eye sensor has several advantages over conventional sensors used for this application, including light weight, low power requirements, fast computation, and a small form factor. This paper reports on the fly-eye sensor development and its application to real-time wing deflection measurement.

  3. Membrane mimetic surface functionalization of nanoparticles: Methods and applications

    PubMed Central

    Weingart, Jacob; Vabbilisetty, Pratima; Sun, Xue-Long

    2013-01-01

    Nanoparticles (NPs), due to their size-dependent physical and chemical properties, have shown remarkable potential for a wide range of applications over the past decades. Particularly, the biological compatibilities and functions of NPs have been extensively studied for expanding their potential in areas of biomedical application such as bioimaging, biosensing, and drug delivery. In doing so, surface functionalization of NPs by introducing synthetic ligands and/or natural biomolecules has become a critical component in regards to the overall performance of the NP system for its intended use. Among known examples of surface functionalization, the construction of an artificial cell membrane structure, based on phospholipids, has proven effective in enhancing biocompatibility and has become a viable alternative to more traditional modifications, such as direct polymer conjugation. Furthermore, certain bioactive molecules can be immobilized onto the surface of phospholipid platforms to generate displays more reminiscent of cellular surface components. Thus, NPs with membrane-mimetic displays have found use in a range of bioimaging, biosensing, and drug delivery applications. This review herein describes recent advances in the preparations and characterization of integrated functional NPs covered by artificial cell membrane structures and their use in various biomedical applications. PMID:23688632

  4. Light-Adaptive Supramolecular Nacre-Mimetic Nanocomposites.

    PubMed

    Zhu, Baolei; Noack, Manuel; Merindol, Remi; Barner-Kowollik, Christopher; Walther, Andreas

    2016-08-10

    Nature provides design paradigms for adaptive, self-healing, and synergistic high-performance structural materials. Nacre's brick-and-mortar architecture is renowned for combining stiffness, toughness, strength, and lightweightness. Although elaborate approaches exist to mimic its static structure and performance, and to incorporate functionalities for the engineering world, there is a profound gap in addressing adaptable mechanical properties, particularly using remote, quick, and spatiotemporal triggers. Here, we demonstrate a generic approach to control the mechanical properties of nacre-inspired nanocomposites by designing a photothermal energy cascade using colloidal graphene as light-harvesting unit and coupling it to molecularly designed, thermoreversible, supramolecular bonds in the nanoconfined soft phase of polymer/nanoclay nacre-mimetics. The light intensity leads to adaptive steady-states balancing energy uptake and dissipation. It programs the mechanical properties and switches the materials from high stiffness/strength to higher toughness within seconds under spatiotemporal control. We envisage possibilities beyond mechanical materials, for example, light-controlled (re)shaping or actuation in highly reinforced nanocomposites. PMID:27455047

  5. Wing patterning gene redefines the mimetic history of Heliconius butterflies

    PubMed Central

    Hines, Heather M.; Counterman, Brian A.; Papa, Riccardo; Albuquerque de Moura, Priscila; Cardoso, Marcio Z.; Linares, Mauricio; Mallet, James; Reed, Robert D.; Jiggins, Chris D.; Kronforst, Marcus R.; McMillan, W. Owen

    2011-01-01

    The mimetic butterflies Heliconius erato and Heliconius melpomene have undergone parallel radiations to form a near-identical patchwork of over 20 different wing-pattern races across the Neotropics. Previous molecular phylogenetic work on these radiations has suggested that similar but geographically disjunct color patterns arose multiple times independently in each species. The neutral markers used in these studies, however, can move freely across color pattern boundaries, and therefore might not represent the history of the adaptive traits as accurately as markers linked to color pattern genes. To assess the evolutionary histories across different loci, we compared relationships among races within H. erato and within H. melpomene using a series of unlinked genes, genes linked to color pattern loci, and optix, a gene recently shown to control red color-pattern variation. We found that although unlinked genes partition populations by geographic region, optix had a different history, structuring lineages by red color patterns and supporting a single origin of red-rayed patterns within each species. Genes closely linked (80–250 kb) to optix exhibited only weak associations with color pattern. This study empirically demonstrates the necessity of examining phenotype-determining genomic regions to understand the history of adaptive change in rapidly radiating lineages. With these refined relationships, we resolve a long-standing debate about the origins of the races within each species, supporting the hypothesis that the red-rayed Amazonian pattern evolved recently and expanded, causing disjunctions of more ancestral patterns. PMID:22084094

  6. A Genetic Linkage Map of the Mimetic Butterfly Heliconius melpomene

    PubMed Central

    Jiggins, Chris D.; Mavarez, Jesus; Beltrán, Margarita; McMillan, W. Owen; Johnston, J. Spencer; Bermingham, Eldredge

    2005-01-01

    Heliconius melpomene is a mimetic butterfly that exhibits great geographic variation in color pattern. We present here a genetic linkage map based on analysis of genetic markers in 73 individuals from a single F2 family, offspring of a cross between H. m. cythera from western Ecuador and H. m. melpomene from French Guiana. A novel “three-step method” is described for the analysis of dominant markers in an F2 cross, using outbred parental strains and taking advantage of the lack of crossing over in female Lepidoptera. This method is likely to prove useful for future mapping studies in outbred species with crossing over restricted to one sex, such as the Lepidoptera and Drosophila. The resulting linkage map has 21 linkage groups corresponding to the 21 chromosomes of H. melpomene and includes 219 AFLP markers, 23 microsatellites, 19 single-copy nuclear genes, and the color pattern switch genes Yb and Sb. The marker density is high, averaging >1/7 cM. The total map length is 1616 cM and the average chromosome length is 77 cM. The genome size of H. melpomene was estimated to be 292 Mb, giving a relationship of physical-to-map distance of 180 kb/cM. This map forms the basis for future comparative linkage analysis of color pattern evolution in Heliconius. PMID:15489522

  7. Synthesis of glycosaminoglycan mimetics through sulfation of polyphenols.

    PubMed

    Al-Horani, Rami A; Karuturi, Rajesh; Verespy, Stephen; Desai, Umesh R

    2015-01-01

    In nearly all cases of biological activity of sulfated GAGs, the sulfate group(s) are critical for interacting with target proteins. A growing paradigm is that appropriate small, sulfated, nonsaccharide GAG mimetics can be designed to either mimic or interfere with the biological functions of natural GAG sequences resulting in the discovery of either antagonist or agonist agents. A number of times these sulfated NSGMs can be computationally designed based on the parent GAG-protein interaction. The small sulfated NSGMs may possess considerable aromatic character so as to engineer hydrophobic, hydrogen-bonding, Coulombic or cation-pi forces in their interactions with target protein(s) resulting in higher specificity of action relative to parent GAGs. The sulfated NSGMs can be easily synthesized in one step from appropriate natural polyphenols through chemical sulfation under microwave-based conditions. We describe step-by-step procedures to perform microwave-based sulfation of several small polyphenol scaffolds so as to prepare homogenous NSGMs containing one to more than 10 sulfate groups per molecule in high yields. PMID:25325944

  8. PKC activation sensitizes basal-like breast cancer cell lines to Smac mimetics

    PubMed Central

    Cornmark, L; Holmgren, C; Masoumi, K; Larsson, C

    2016-01-01

    There is a need for novel strategies to initiate cancer cell death. One approach is the use of Smac mimetics, which antagonize inhibitor of apoptosis proteins (IAPs). Recent studies have shown that combinations of Smac mimetics such as LBW242 or LCL161 in combination with chemotherapeutic agents increase cancer cell death. Here we show that the protein kinase C (PKC) activator TPA together with the Smac mimetic LBW242 induces cell death in two basal breast cancer cell lines (MDA-MB-468 and BT-549) that are resistant to Smac mimetic as single agent. Ten other LBW242-insensitive cancer cell lines were not influenced by the TPA+LBW242 combination. The TPA+LBW242 effect was suppressed by the PKC inhibitor GF109203X, indicating dependence on PKC enzymatic activity. The PKC effect was mediated via increased synthesis and release of TNFα, which can induce death in the presence of Smac mimetics. The cell death, coinciding with caspase-3 cleavage, was suppressed by caspase inhibition and preceded by the association of RIP1 with caspase-8, as seen in complex II formation. Smac mimetics, but not TPA, induced the non-canonical NF-κB pathway in both MDA-MB-231 and MDA-MB-468 cells. Blocking the canonical NF-κB pathway suppressed TPA induction of TNFα in MDA-MB-468 cells whereas isolated downregulation of either the canonical or non-canonical pathways did not abolish the Smac mimetic induction of the NF-κB driven genes TNFα and BIRC3 in MDA-MB-231 cells although the absolute levels were suppressed. A combined downregulation of the canonical and non-canonical pathways further suppressed TNFα levels and inhibited Smac mimetic-mediated cell death. Our data suggest that in certain basal breast cancer cell lines co-treatment of TPA with a Smac mimetic induces cell death highlighting the potential of using these pathways as molecular targets for basal-like breast cancers. PMID:27551497

  9. Furoxans (1,2,5-Oxadiazole-N-Oxides) as Novel NO Mimetic Neuroprotective and Procognitive Agents

    SciTech Connect

    Schiefer, Isaac T.; VandeVrede, Lawren; Fa; , Mauro; Arancio, Ottavio; Thatcher, Gregory R.J.

    2012-08-31

    Furoxans (1,2,5-oxadiazole-N-oxides) are thiol-bioactivated NO-mimetics that have not hitherto been studied in the CNS. Incorporation of varied substituents adjacent to the furoxan ring system led to modulation of reactivity toward bioactivation, studied by HPLC-MS/MS analysis of reaction products. Attenuated reactivity unmasked the cytoprotective actions of NO in contrast to the cytotoxic actions of higher NO fluxes reported previously for furoxans. Neuroprotection was observed in primary neuronal cell cultures following oxygen glucose deprivation (OGD). Neuroprotective activity was observed to correlate with thiol-dependent bioactivation to produce NO{sub 2}{sup -}, but not with depletion of free thiol itself. Neuroprotection was abrogated upon cotreatment with a sGC inhibitor, ODQ, thus supporting activation of the NO/sGC/CREB signaling cascade by furoxans. Long-term potentiation (LTP), essential for learning and memory, has been shown to be potentiated by NO signaling, therefore, a peptidomimetic furoxan was tested in hippocampal slices treated with oligomeric amyloid-{beta} peptide (A{beta}) and was shown to restore synaptic function. The novel observation of furoxan activity of potential therapeutic use in the CNS warrants further studies.

  10. A synthetic, bioactive PDGF mimetic with binding to both alpha-PDGF and beta-PDGF receptors.

    PubMed

    Lin, Xinhua; Takahashi, Kazuyuki; Liu, Yi; Derrien, Alexandrine; Zamora, Paul O

    2007-04-01

    A multi-domain peptide, PAB2-1c, was designed and synthesized as a bioactive mimic of PDGF. PBA2-1c bound to both alpha- and beta-PDGF receptors as determined by surface plasmon resonance (SPR). The equilibrium dissociation constant (Kd) of binding to alpha-PDGF receptors by PAB2-1c (1.7 x 10(-8) M) compared favorably rhPDGF-AA (1.34 x 10(-8) M). Binding to -PDGF receptor by PAB2-1c (2.2 x 10(-8) M) was less favorable than, that of recombinant human PDGFBB (1.59 x 10(-9) M). Interestingly, PBA2-1c bound to these two receptors with similar affinity suggesting that, PBA2-1c was not PDGF receptor selective. In a murine myoblast cell line C2C12, PBA2-1c increased the tyrosine phosphorylation on PDGF receptors and the phosphorylation of AKT and ERK1/2 in a concentration-related manner. PBA2-1c also stimulated an increase in cell proliferation, cell migration, and collagen gel contraction. In these cell-based assays, PAB2-1c was effective at 1 microg/ml or lesser. The results support the hypothesis that PBA2-1c is a mimetic of PDGF, although it has a more promiscuous receptor interaction. PMID:17852406

  11. 3D Cell Entrapment as a Function of the Weight Percent of Peptide-Amphiphile Hydrogels

    PubMed Central

    Scott, Carolyn M.; Forster, Colleen L.; Kokkoli, Efrosini

    2015-01-01

    The design of scaffolds which mimic the stiffness, nanofiber structure, and biochemistry of the native extra-cellular matrix (ECM) has been a major objective for the tissue engineering field. Furthermore, mimicking the innate three dimensional (3D) environment of the ECM has been shown to significantly alter cellular response compared to traditional two dimensional (2D) culture. We report the development of a self-assembling, fibronectin-mimetic, peptide-amphiphile nanofiber scaffold for 3D cell culture. To form such a scaffold, 5 mol% of a bioactive PR_g fibronectin-mimetic peptide-amphiphile was mixed with 95 mol% of a diluent peptide-amphiphile (E2) whose purpose was to neutralize electrostatic interactions, increase the gelation kinetics and promote cell survival. Atomic force microscopy verified the fibrilar structure of the gels and the mechanical properties were characterized for various weight percent (wt%) formulations of the 5 mol% PR_g - 95 mol% E2 peptide-amphiphile mixture. The 0.5 wt% formulations had an elastic modulus of 429.0 ± 21.3 Pa while the 1.0 wt% peptide-amphiphile hydrogels had an elastic modulus of 808.6 ± 38.1 Pa. The presence of entrapped cells in the gels decreased the elastic modulus and the decrease was a function of the cell loading. While both formulations supported cell proliferation, the 0.5 wt% gels supported significantly greater NIH3T3/GFP fibroblast cell proliferation throughout the gels than the 1.0 wt% gels. However, compared to the 0.5 wt% formulations, the 1.0 wt% hydrogels promoted greater increase in mRNA expression and production of fibronectin and type IV collagen ECM proteins. This study suggests that this fibronectin-mimetic scaffold holds great promise in the advance of 3D culture applications and cell therapies. PMID:25970351

  12. Nacre-mimetics with synthetic nanoclays up to ultrahigh aspect ratios.

    PubMed

    Das, Paramita; Malho, Jani-Markus; Rahimi, Khosrow; Schacher, Felix H; Wang, Baochun; Demco, Dan Eugen; Walther, Andreas

    2015-01-01

    Nacre-mimetics hold great promise as mechanical high-performance and functional materials. Here we demonstrate large progress of mechanical and functional properties of self-assembled polymer/nanoclay nacre-mimetics by using synthetic nanoclays with aspect ratios covering three orders in magnitude (25-3,500). We establish comprehensive relationships among structure formation, nanostructuration, deformation mechanisms and mechanical properties as a function of nanoclay aspect ratio, and by tuning the viscoelastic properties of the soft phase via hydration. Highly ordered, large-scale nacre-mimetics are obtained even for low aspect ratio nanoplatelets and show pronounced inelastic deformation with very high toughness, while those formed by ultralarge nanoplatelets exhibit superb stiffness and strength, previously only reachable for highly crosslinked materials. Regarding functionalities, we report formerly impossible glass-like transparency, and excellent gas barrier considerably exceeding earlier nacre-mimetics based on natural nanoclay. Our study enables rational design of future high-performance nacre-mimetic materials and opens avenues for ecofriendly, transparent, self-standing and strong advanced barrier materials. PMID:25601360

  13. Nacre-mimetics with synthetic nanoclays up to ultrahigh aspect ratios

    NASA Astrophysics Data System (ADS)

    Das, Paramita; Malho, Jani-Markus; Rahimi, Khosrow; Schacher, Felix H.; Wang, Baochun; Demco, Dan Eugen; Walther, Andreas

    2015-01-01

    Nacre-mimetics hold great promise as mechanical high-performance and functional materials. Here we demonstrate large progress of mechanical and functional properties of self-assembled polymer/nanoclay nacre-mimetics by using synthetic nanoclays with aspect ratios covering three orders in magnitude (25-3,500). We establish comprehensive relationships among structure formation, nanostructuration, deformation mechanisms and mechanical properties as a function of nanoclay aspect ratio, and by tuning the viscoelastic properties of the soft phase via hydration. Highly ordered, large-scale nacre-mimetics are obtained even for low aspect ratio nanoplatelets and show pronounced inelastic deformation with very high toughness, while those formed by ultralarge nanoplatelets exhibit superb stiffness and strength, previously only reachable for highly crosslinked materials. Regarding functionalities, we report formerly impossible glass-like transparency, and excellent gas barrier considerably exceeding earlier nacre-mimetics based on natural nanoclay. Our study enables rational design of future high-performance nacre-mimetic materials and opens avenues for ecofriendly, transparent, self-standing and strong advanced barrier materials.

  14. Static spherically symmetric solutions in mimetic gravity: rotation curves and wormholes

    NASA Astrophysics Data System (ADS)

    Myrzakulov, Ratbay; Sebastiani, Lorenzo; Vagnozzi, Sunny; Zerbini, Sergio

    2016-06-01

    In this work, we analyse static spherically symmetric solutions in the framework of mimetic gravity, an extension of general relativity where the conformal degree of freedom of gravity is isolated in a covariant fashion. Here we extend previous works by considering, in addition, a potential for the mimetic field. An appropriate choice of such a potential allows for the reconstruction of a number of interesting cosmological and astrophysical scenarios. We explicitly show how to reconstruct such a potential for a general static spherically symmetric space-time. A number of applications and scenarios are then explored, among which are traversable wormholes. Finally, we analytically reconstruct potentials, which leads to solutions to the equations of motion featuring polynomial corrections to the Schwarzschild space-time. Accurate choices for such corrections could provide an explanation for the inferred flat rotation curves of spiral galaxies within the mimetic gravity framework, without the need for particle dark matter.

  15. The arbitrary order mixed mimetic finite difference method for the diffusion equation

    DOE PAGESBeta

    Gyrya, Vitaliy; Lipnikov, Konstantin; Manzini, Gianmarco

    2016-05-01

    Here, we propose an arbitrary-order accurate mimetic finite difference (MFD) method for the approximation of diffusion problems in mixed form on unstructured polygonal and polyhedral meshes. As usual in the mimetic numerical technology, the method satisfies local consistency and stability conditions, which determines the accuracy and the well-posedness of the resulting approximation. The method also requires the definition of a high-order discrete divergence operator that is the discrete analog of the divergence operator and is acting on the degrees of freedom. The new family of mimetic methods is proved theoretically to be convergent and optimal error estimates for flux andmore » scalar variable are derived from the convergence analysis. A numerical experiment confirms the high-order accuracy of the method in solving diffusion problems with variable diffusion tensor. It is worth mentioning that the approximation of the scalar variable presents a superconvergence effect.« less

  16. An overview on antidiabetic medicinal plants having insulin mimetic property.

    PubMed

    Patel, D K; Prasad, S K; Kumar, R; Hemalatha, S

    2012-04-01

    Diabetes mellitus is one of the common metabolic disorders acquiring around 2.8% of the world's population and is anticipated to cross 5.4% by the year 2025. Since long back herbal medicines have been the highly esteemed source of medicine therefore, they have become a growing part of modern, high-tech medicine. In view of the above aspects the present review provides profiles of plants (65 species) with hypoglycaemic properties, available through literature source from various database with proper categorization according to the parts used, mode of reduction in blood glucose (insulinomimetic or insulin secretagogues activity) and active phytoconstituents having insulin mimetics activity. From the review it was suggested that, plant showing hypoglycemic potential mainly belongs to the family Leguminoseae, Lamiaceae, Liliaceae, Cucurbitaceae, Asteraceae, Moraceae, Rosaceae and Araliaceae. The most active plants are Allium sativum, Gymnema sylvestre, Citrullus colocynthis, Trigonella foenum greacum, Momordica charantia and Ficus bengalensis. The review describes some new bioactive drugs and isolated compounds from plants such as roseoside, epigallocatechin gallate, beta-pyrazol-1-ylalanine, cinchonain Ib, leucocyandin 3-O-beta-d-galactosyl cellobioside, leucopelargonidin-3- O-alpha-L rhamnoside, glycyrrhetinic acid, dehydrotrametenolic acid, strictinin, isostrictinin, pedunculagin, epicatechin and christinin-A showing significant insulinomimetic and antidiabetic activity with more efficacy than conventional hypoglycaemic agents. Thus, from the review majorly, the antidiabetic activity of medicinal plants is attributed to the presence of polyphenols, flavonoids, terpenoids, coumarins and other constituents which show reduction in blood glucose levels. The review also discusses the management aspect of diabetes mellitus using these plants and their active principles. PMID:23569923

  17. An overview on antidiabetic medicinal plants having insulin mimetic property

    PubMed Central

    Patel, DK; Prasad, SK; Kumar, R; Hemalatha, S

    2012-01-01

    Diabetes mellitus is one of the common metabolic disorders acquiring around 2.8% of the world's population and is anticipated to cross 5.4% by the year 2025. Since long back herbal medicines have been the highly esteemed source of medicine therefore, they have become a growing part of modern, high-tech medicine. In view of the above aspects the present review provides profiles of plants (65 species) with hypoglycaemic properties, available through literature source from various database with proper categorization according to the parts used, mode of reduction in blood glucose (insulinomimetic or insulin secretagogues activity) and active phytoconstituents having insulin mimetics activity. From the review it was suggested that, plant showing hypoglycemic potential mainly belongs to the family Leguminoseae, Lamiaceae, Liliaceae, Cucurbitaceae, Asteraceae, Moraceae, Rosaceae and Araliaceae. The most active plants are Allium sativum, Gymnema sylvestre, Citrullus colocynthis, Trigonella foenum greacum, Momordica charantia and Ficus bengalensis. The review describes some new bioactive drugs and isolated compounds from plants such as roseoside, epigallocatechin gallate, beta-pyrazol-1-ylalanine, cinchonain Ib, leucocyandin 3-O-beta-d-galactosyl cellobioside, leucopelargonidin-3- O-alpha-L rhamnoside, glycyrrhetinic acid, dehydrotrametenolic acid, strictinin, isostrictinin, pedunculagin, epicatechin and christinin-A showing significant insulinomimetic and antidiabetic activity with more efficacy than conventional hypoglycaemic agents. Thus, from the review majorly, the antidiabetic activity of medicinal plants is attributed to the presence of polyphenols, flavonoids, terpenoids, coumarins and other constituents which show reduction in blood glucose levels. The review also discusses the management aspect of diabetes mellitus using these plants and their active principles. PMID:23569923

  18. Characterization of Phospho-(Tyrosine)-Mimetic Calmodulin Mutants

    PubMed Central

    Stateva, Silviya R.; Salas, Valentina; Benaim, Gustavo; Menéndez, Margarita; Solís, Dolores; Villalobo, Antonio

    2015-01-01

    Calmodulin (CaM) phosphorylated at different serine/threonine and tyrosine residues is known to exert differential regulatory effects on a variety of CaM-binding enzymes as compared to non-phosphorylated CaM. In this report we describe the preparation and characterization of a series of phospho-(Y)-mimetic CaM mutants in which either one or the two tyrosine residues present in CaM (Y99 and Y138) were substituted to aspartic acid or glutamic acid. It was expected that the negative charge of the respective carboxyl group of these amino acids mimics the negative charge of phosphate and reproduce the effects that distinct phospho-(Y)-CaM species may have on target proteins. We describe some physicochemical properties of these CaM mutants as compared to wild type CaM, after their expression in Escherichia coli and purification to homogeneity, including: i) changes in their electrophoretic mobility in the absence and presence of Ca2+; ii) ultraviolet (UV) light absorption spectra, far- and near-UV circular dichroism data; iii) thermal stability in the absence and presence of Ca2+; and iv) Tb3+-emitted fluorescence upon tyrosine excitation. We also describe some biochemical properties of these CaM mutants, such as their differential phosphorylation by the tyrosine kinase c-Src, and their action as compared to wild type CaM, on the activity of two CaM-dependent enzymes: cyclic nucleotide phosphodiesterase 1 (PDE1) and endothelial nitric oxide synthase (eNOS) assayed in vitro. PMID:25830911

  19. Preclinical Pharmacokinetic Analysis of NOV-002, a Glutathione Disulfide Mimetic

    PubMed Central

    Uys, Joachim D.; Manevich, Yefim; DeVane, Lindsay C.; He, Lin; Garret, Tracy E.; Pazoles, Christopher J.; Tew, Kenneth D.; Townsend, Danyelle M.

    2010-01-01

    Summary NOV-002 is a glutathione disulfide (GSSG) mimetic that is in Phase III clinical trials for the treatment of advanced non-small cell lung cancer and other oncology indications. GSSG is reduced by glutathione reductase (GR) to form glutathione (GSH), thereby maintaining redox homeostasis. The purpose of the study was to report the pharmacokinetic properties of NOV-002 and evaluate the effect that NOV-002 elicits in redox homeostasis. The pharmacokinetic analysis and tissue distribution of NOV-002 and GSH was evaluated in mice following a dose of 250 mg/kg, i.p. The redox potential and total protein thiol status was calculated. Here we show that NOV-002 is a substrate for GR and that GSH is a primary metabolite. Nonlinear pharmacokinetic modeling predicted that the estimated absorption and elimination rate constants correspond to a half-life of ~13 mins with an AUC of 1.18 μg.h/ml, a Cmax of 2.16 μg/ml and a volume of distribution of 42.61 L/kg. In addition, measurement of the redox potential and total protein thiol status indicated the generation of a transient oxidative signal in the plasma compartment after administration of NOV-002. These results indicate that NOV-002 exerts kinetic and dynamic effects in mice consistent with the GSSG component as the active pharmacological constituent of the drug. A longer-lasting decrease in total plasma free thiol content was also seen, suggesting that the oxidative effect of the GSSG from NOV-002 was impacting redox homeostasis. PMID:20359856

  20. Preclinical pharmacokinetic analysis of NOV-002, a glutathione disulfide mimetic.

    PubMed

    Uys, J D; Manevich, Y; Devane, L C; He, L; Garret, T E; Pazoles, C J; Tew, K D; Townsend, D M

    2010-09-01

    NOV-002 is a glutathione disulfide (GSSG) mimetic that is the subject of clinical investigation in oncology indications. GSSG is reduced by glutathione reductase (GR) to form glutathione (GSH), thereby maintaining redox homeostasis. The purpose of the study was to report the pharmacokinetic properties of NOV-002 and evaluate the effect that NOV-002 elicits in redox homeostasis. The pharmacokinetic analysis and tissue distribution of NOV-002 and GSH was evaluated in mice following a dose of 250 mg/kg, i.p. The redox potential and total protein thiol status was calculated. Here we show that NOV-002 is a substrate for GR and that GSH is a primary metabolite. Non-linear pharmacokinetic modeling predicted that the estimated absorption and elimination rate constants correspond to a half-life of approximately 13 min with an AUC of 1.18 μgh/mL, a C(max) of 2.16 μg/ml and a volume of distribution of 42.61 L/kg. In addition, measurement of the redox potential and total protein thiol status indicated the generation of a transient oxidative signal in the plasma compartment after administration of NOV-002. These results indicate that NOV-002 exerts kinetic and dynamic effects in mice consistent with the GSSG component as the active pharmacological constituent of the drug. A longer-lasting decrease in total plasma free thiol content was also seen, suggesting that the oxidative effect of the GSSG from NOV-002 was impacting redox homeostasis. PMID:20359856

  1. Exercise-mimetic AICAR transiently benefits brain function

    PubMed Central

    Guerrieri, Davide; van Praag, Henriette

    2015-01-01

    Exercise enhances learning and memory in animals and humans. The role of peripheral factors that may trigger the beneficial effects of running on brain function has been sparsely examined. In particular, it is unknown whether AMP-kinase (AMPK) activation in muscle can predict enhancement of brain plasticity. Here we compare the effects of running and administration of AMPK agonist 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR, 500 mg/kg), for 3, 7 or 14 days in one-month-old male C57BL/6J mice, on muscle AMPK signaling. At the time-points where we observed equivalent running- and AICAR-induced muscle pAMPK levels (7 and 14 days), cell proliferation, synaptic plasticity and gene expression, as well as markers of oxidative stress and inflammation in the dentate gyrus (DG) of the hippocampus and lateral entorhinal cortex (LEC) were evaluated. At the 7-day time-point, both regimens increased new DG cell number and brain-derived neurotrophic factor (BDNF) protein levels. Furthermore, microarray analysis of DG and LEC tissue showed a remarkable overlap between running and AICAR in the regulation of neuronal, mitochondrial and metabolism related gene classes. Interestingly, while similar outcomes for both treatments were stable over time in muscle, in the brain an inversion occurred at fourteen days. The compound no longer increased DG cell proliferation or neurotrophin levels, and upregulated expression of apoptotic genes and inflammatory cytokine interleukin-1β. Thus, an exercise mimetic that produces changes in muscle consistent with those of exercise does not have the same sustainable positive effects on the brain, indicating that only running consistently benefits brain function. PMID:26286955

  2. Peptide library approach to uncover phosphomimetic inhibitors of the BRCA1 C-terminal domain.

    PubMed

    White, E Railey; Sun, Luxin; Ma, Zhong; Beckta, Jason M; Danzig, Brittany A; Hacker, David E; Huie, Melissa; Williams, David C; Edwards, Ross A; Valerie, Kristoffer; Glover, J N Mark; Hartman, Matthew C T

    2015-05-15

    Many intracellular protein-protein interactions are mediated by the phosphorylation of serine, and phosphoserine-containing peptides can inhibit these interactions. However, hydrolysis of the phosphate by phosphatases, and the poor cell permeability associated with phosphorylated peptides has limited their utility in cellular and in vivo contexts. Compounding the problem, strategies to replace phosphoserine in peptide inhibitors with easily accessible mimetics (such as Glu or Asp) routinely fail. Here, we present an in vitro selection strategy for replacement of phosphoserine. Using mRNA display, we created a 10 trillion member structurally diverse unnatural peptide library. From this library, we found a peptide that specifically binds to the C-terminal domain (BRCT)2 of breast cancer associated protein 1 (BRCA1) with an affinity comparable to phosphorylated peptides. A crystal structure of the peptide bound reveals that the pSer-x-x-Phe motif normally found in BRCA1 (BRCT)2 binding partners is replaced by a Glu-x-x-4-fluoroPhe and that the peptide picks up additional contacts on the protein surface not observed in cognate phosphopeptide binding. Expression of the peptide in human cells led to defects in DNA repair by homologous recombination, a process BRCA1 is known to coordinate. Overall, this work validates a new in vitro selection approach for the development of inhibitors of protein-protein interactions mediated by serine phosphorylation. PMID:25654734

  3. Peptide Library Approach to Uncover Phosphomimetic Inhibitors of the BRCA1 C-Terminal Domain

    PubMed Central

    White, E. Railey; Sun, Luxin; Ma, Zhong; Beckta, Jason M.; Danzig, Brittany A.; Hacker, David E.; Huie, Melissa; Williams, David C.; Edwards, Ross A.; Valerie, Kristoffer; Mark Glover, J. N.; Hartman, Matthew C. T.

    2015-01-01

    Many intracellular protein–protein interactions are mediated by the phosphorylation of serine, and phosphoserine-containing peptides can inhibit these interactions. However, hydrolysis of the phosphate by phosphatases, and the poor cell permeability associated with phosphorylated peptides has limited their utility in cellular and in vivo contexts. Compounding the problem, strategies to replace phosphoserine in peptide inhibitors with easily accessible mimetics (such as Glu or Asp) routinely fail. Here, we present an in vitro selection strategy for replacement of phosphoserine. Using mRNA display, we created a 10 trillion member structurally diverse unnatural peptide library. From this library, we found a peptide that specifically binds to the C-terminal domain (BRCT)2 of breast cancer associated protein 1 (BRCA1) with an affinity comparable to phosphorylated peptides. A crystal structure of the peptide bound reveals that the pSer-x-x-Phe motif normally found in BRCA1 (BRCT)2 binding partners is replaced by a Glu-x-x-4-fluoroPhe and that the peptide picks up additional contacts on the protein surface not observed in cognate phosphopeptide binding. Expression of the peptide in human cells led to defects in DNA repair by homologous recombination, a process BRCA1 is known to coordinate. Overall, this work validates a new in vitro selection approach for the development of inhibitors of protein–protein interactions mediated by serine phosphorylation. PMID:25654734

  4. A note on Schwarzschild-de Sitter black holes in mimetic F(R) gravity

    NASA Astrophysics Data System (ADS)

    Oikonomou, V. K.

    2016-05-01

    In this paper, we investigate the conditions under which a Schwarzschild-de Sitter black hole spacetime is a solution of the mimetic F(R) gravity with Lagrange multiplier and potential. As we demonstrate, the resulting mimetic F(R) gravity is a slight modification of the ordinary F(R) gravity case, however the resulting perturbation equations are not in all cases identical to the ordinary F(R) gravity case. In the latter case, the perturbation equations are identical to the ones corresponding to the Reissner-Nordström anti-de Sitter black hole.

  5. Antimicrobial peptides.

    PubMed

    Zhang, Ling-Juan; Gallo, Richard L

    2016-01-11

    Antimicrobial peptides and proteins (AMPs) are a diverse class of naturally occurring molecules that are produced as a first line of defense by all multicellular organisms. These proteins can have broad activity to directly kill bacteria, yeasts, fungi, viruses and even cancer cells. Insects and plants primarily deploy AMPs as an antibiotic to protect against potential pathogenic microbes, but microbes also produce AMPs to defend their environmental niche. In higher eukaryotic organisms, AMPs can also be referred to as 'host defense peptides', emphasizing their additional immunomodulatory activities. These activities are diverse, specific to the type of AMP, and include a variety of cytokine and growth factor-like effects that are relevant to normal immune homeostasis. In some instances, the inappropriate expression of AMPs can also induce autoimmune diseases, thus further highlighting the importance of understanding these molecules and their complex activities. This Primer will provide an update of our current understanding of AMPs. PMID:26766224

  6. Peptide arrays for screening cancer specific peptides.

    PubMed

    Ahmed, Sahar; Mathews, Anu Stella; Byeon, Nara; Lavasanifar, Afsaneh; Kaur, Kamaljit

    2010-09-15

    In this paper, we describe a novel method to screen peptides for specific recognition by cancer cells. Seventy peptides were synthesized on a cellulose membrane in an array format, and a direct method to study the peptide-whole cell interaction was developed. The relative binding affinity of the cells for different peptides with respect to a lead 12-mer p160 peptide, identified by phage display, was evaluated using the CyQUANT fluorescence of the bound cells. Screening allowed identification of at least five new peptides that displayed higher affinity (up to 3-fold) for MDA-MB-435 and MCF-7 human cancer cells compared to the p160 peptide. These peptides showed very little binding to the control (noncancerous) human umbilical vein endothelial cells (HUVECs). Three of these peptides were synthesized separately and labeled with fluorescein isothiocyanate (FITC) to study their uptake and interaction with the cancer and control cells using confocal laser scanning microscopy and flow cytometry. The results confirmed the high and specific affinity of an 11-mer peptide 11 (RGDPAYQGRFL) and a 10-mer peptide 18 (WXEAAYQRFL) for the cancer cells versus HUVECs. Peptide 11 binds different receptors on target cancer cells as its sequence contains multiple recognition motifs, whereas peptide 18 binds mainly to the putative p160 receptor. The peptide array-whole cell binding assay reported here is a complementary method to phage display for further screening and optimization of cancer targeting peptides for cancer therapy and diagnosis. PMID:20799711

  7. BAX-BAK1-independent LC3B lipidation by BH3 mimetics is unrelated to BH3 mimetic activity and has only minimal effects on autophagic flux.

    PubMed

    Reljic, Boris; Conos, Stephanie; Lee, Erinna F; Garnier, Jean-Marc; Dong, Li; Lessene, Guillaume; Fairlie, W Douglas; Vaux, David L; Lindqvist, Lisa M

    2016-07-01

    Inhibition of prosurvival BCL2 family members can induce autophagy, but the mechanism is controversial. We have provided genetic evidence that BCL2 family members block autophagy by inhibiting BAX and BAK1, but others have proposed they instead inhibit BECN1. Here we confirm that small molecule BH3 mimetics can induce BAX- and BAK1-independent MAP1LC3B/LC3B lipidation, but this only occurred at concentrations far greater than required to induce apoptosis and dissociate canonical BH3 domain-containing proteins that bind more tightly than BECN1. Because high concentrations of a less-active enantiomer of ABT-263 also induced BAX- and BAK1-independent LC3B lipidation, induction of this marker of autophagy appears to be an off-target effect. Indeed, robust autophagic flux was not induced by BH3 mimetic compounds in the absence of BAX and BAK1. Therefore at concentrations that are on target and achievable in vivo, BH3 mimetics only induce autophagy in a BAX- and BAK1-dependent manner. PMID:27172402

  8. Inhibition of Rotavirus Infectivity by a Neoglycolipid Receptor Mimetic

    PubMed Central

    Bergner, Daniel W.; Kuhlenschmidt, Theresa B.; Hanafin, William P.; Firkins, Lawrence D.; Kuhlenschmidt, Mark S.

    2011-01-01

    -scale production capabilities make SLPE a promising candidate for further exploration as a possible prophylactic or therapeutic nutriceutical for combating rotavirus disease in animals. Most importantly, the results presented here provide proof of concept that the nutriceutical approach of providing natural or synthetic dietary receptor mimetics for protection against gastrointestinal virus infectious disease in all species is plausible. PMID:22254094

  9. Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R) Gravity

    NASA Astrophysics Data System (ADS)

    Oikonomou, V. K.

    2016-05-01

    In this paper we study under which conditions the Reissner-Nordstr\\"om-anti de Sitter black hole can be a solution of the vacuum mimetic $F(R)$ gravity with Lagrange multiplier and mimetic scalar potential. As we demonstrate, the resulting picture in the mimetic $F(R)$ gravity case, is different in comparison to the ordinary $F(R)$ gravity case, with the two descriptions resulting to a different set of constraints that need to hold true. We also investigate the metric perturbations in the mimetic $F(R)$ gravity case, for the Reissner-Nordstr\\"om-anti de Sitter black hole metric, at first order of the perturbed variables. Interestingly enough, the resulting equations are identical to the ones corresponding to the ordinary $F(R)$ gravity Reissner-Nordstr\\"om-anti de Sitter black hole, at least at first order. We attribute this feature to the particular form of the Reissner-Nordstr\\"om-anti de Sitter metric, and we speculate for which cases there could be differences between the mimetic and non-mimetic case. Since the perturbation equations are the same for the two cases, it is possible to have black hole instabilities in the mimetic $F(R)$ gravity case too, which can be interpreted as anti-evaporation of the black hole.

  10. Comparative Allometric Growth of the Mimetic Ephippid Reef Fishes Chaetodipterus faber and Platax orbicularis.

    PubMed

    Barros, Breno; Sakai, Yoichi; Pereira, Pedro H C; Gasset, Eric; Buchet, Vincent; Maamaatuaiahutapu, Moana; Ready, Jonathan S; Oliveira, Yrlan; Giarrizzo, Tommaso; Vallinoto, Marcelo

    2015-01-01

    Mimesis is a relatively widespread phenomenon among reef fish, but the ontogenetic processes relevant for mimetic associations in fish are still poorly understood. In the present study, the allometric growth of two allopatric leaf-mimetic species of ephippid fishes, Chaetodipterus faber from the Atlantic and Platax orbicularis from the Indo-Pacific, was analyzed using ten morphological variables. The development of fins was considered owing to the importance of these structures for mimetic behaviors during early life stages. Despite the anatomical and behavioral similarities in both juvenile and adult stages, C. faber and P. orbicularis showed distinct patterns of growth. The overall shape of C. faber transforms from a rounded-shape in mimetic juveniles to a lengthened profile in adults, while in P. orbicularis, juveniles present an oblong profile including dorsal and anal fins, with relative fin size diminishing while the overall profile grows rounder in adults. Although the two species are closely-related, the present results suggest that growth patterns in C. faber and P. orbicularis are different, and are probably independent events in ephippids that have resulted from similar selective processes. PMID:26630347

  11. Solving Navier-Stokes' equation using Castillo-Grone's mimetic difference operators on GPUs

    NASA Astrophysics Data System (ADS)

    Abouali, Mohammad; Castillo, Jose

    2012-11-01

    This paper discusses the performance and the accuracy of Castillo-Grone's (CG) mimetic difference operator in solving the Navier-Stokes' equation in order to simulate oceanic and atmospheric flows. The implementation is further adapted to harness the power of the many computing cores available on the Graphics Processing Units (GPUs) and the speedup is discussed.

  12. Comparative Allometric Growth of the Mimetic Ephippid Reef Fishes Chaetodipterus faber and Platax orbicularis

    PubMed Central

    Barros, Breno; Sakai, Yoichi; Pereira, Pedro H. C.; Gasset, Eric; Buchet, Vincent; Maamaatuaiahutapu, Moana; Ready, Jonathan S.; Oliveira, Yrlan; Giarrizzo, Tommaso; Vallinoto, Marcelo

    2015-01-01

    Mimesis is a relatively widespread phenomenon among reef fish, but the ontogenetic processes relevant for mimetic associations in fish are still poorly understood. In the present study, the allometric growth of two allopatric leaf-mimetic species of ephippid fishes, Chaetodipterus faber from the Atlantic and Platax orbicularis from the Indo-Pacific, was analyzed using ten morphological variables. The development of fins was considered owing to the importance of these structures for mimetic behaviors during early life stages. Despite the anatomical and behavioral similarities in both juvenile and adult stages, C. faber and P. orbicularis showed distinct patterns of growth. The overall shape of C. faber transforms from a rounded-shape in mimetic juveniles to a lengthened profile in adults, while in P. orbicularis, juveniles present an oblong profile including dorsal and anal fins, with relative fin size diminishing while the overall profile grows rounder in adults. Although the two species are closely-related, the present results suggest that growth patterns in C. faber and P. orbicularis are different, and are probably independent events in ephippids that have resulted from similar selective processes. PMID:26630347

  13. A Case of Mimetic Isomorphism: A Short-Cut to Increasing Loyalty to Academia

    ERIC Educational Resources Information Center

    Orkodashvili, Mariam

    2008-01-01

    The paper discusses the process of shortening career path to leadership positions in academia that could serve as an example of mimetic isomorphism, where university tries to apply business-like quick result-oriented strategies. This strategy incentivizes young faculty to stay in universities and keep loyalty to academia. This process could also…

  14. The relationship between mimetic imperfection and phenotypic variation in insect colour patterns.

    PubMed Central

    Holloway, Graham; Gilbert, Francis; Brandt, Amoret

    2002-01-01

    Many hoverflies (Syrphidae) mimic wasps or bees through colour or behavioural adaptations. The relationship between phenotypic variation in colour pattern and mimetic perfection (as determined by pigeons) was investigated in three species of Müllerian mimics (Vespula spp.) and 10 Batesian hoverfly mimics, plus two non-mimetic species of flies. Four predictions were tested: (i) Batesian mimics might be imperfect because they are in the process of evolving towards perfection, hence there should be a positive relationship between variation and imperfection; (ii) some Batesian mimics are imperfect because they do not have the appropriate genetic variation to improve and have evolved to be as good as possible, hence there should be no differences between species, all displaying a low level of variation; (iii) very common hoverflies should show the highest levels of variation because they outnumber their models, resulting in high predation and a breakdown in the mimetic relationship; and (iv) social wasps (Vespula) have such a powerful defence that anything resembling a wasp, both Müllerian and perfect Batesian mimics, would be avoided, resulting in relaxed selection and high variance. Poor mimics may still evolve to resemble wasps as well as possible and display lower levels of variation. The data only provided support for the fourth prediction. The Müllerian mimics, one of the most perfect Batesian mimics, and the non-mimetic flies displayed much higher levels of variation than the other species of Batesian mimics. PMID:11886630

  15. A network pharmacology approach reveals new candidate caloric restriction mimetics in C. elegans.

    PubMed

    Calvert, Shaun; Tacutu, Robi; Sharifi, Samim; Teixeira, Rute; Ghosh, Pratul; de Magalhães, João Pedro

    2016-04-01

    Caloric restriction (CR), a reduction in calorie intake without malnutrition, retards aging in several animal models from worms to mammals. Developing CR mimetics, compounds that reproduce the longevity benefits of CR without its side effects, is of widespread interest. Here, we employed the Connectivity Map to identify drugs with overlapping gene expression profiles with CR. Eleven statistically significant compounds were predicted as CR mimetics using this bioinformatics approach. We then tested rapamycin, allantoin, trichostatin A, LY-294002 and geldanamycin in Caenorhabditis elegans. An increase in lifespan and healthspan was observed for all drugs except geldanamycin when fed to wild-type worms, but no lifespan effects were observed in eat-2 mutant worms, a genetic model of CR, suggesting that life-extending effects may be acting via CR-related mechanisms. We also treated daf-16 worms with rapamycin, allantoin or trichostatin A, and a lifespan extension was observed, suggesting that these drugs act via DAF-16-independent mechanisms, as would be expected from CR mimetics. Supporting this idea, an analysis of predictive targets of the drugs extending lifespan indicates various genes within CR and longevity networks. We also assessed the transcriptional profile of worms treated with either rapamycin or allantoin and found that both drugs use several specific pathways that do not overlap, indicating different modes of action for each compound. The current work validates the capabilities of this bioinformatic drug repositioning method in the context of longevity and reveals new putative CR mimetics that warrant further studies. PMID:26676933

  16. Novel Apo E-Derived ABCA1 Agonist Peptide (CS-6253) Promotes Reverse Cholesterol Transport and Induces Formation of preβ-1 HDL In Vitro

    PubMed Central

    Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques

    2015-01-01

    Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from the carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

  17. Novel apo E-derived ABCA1 agonist peptide (CS-6253) promotes reverse cholesterol transport and induces formation of preβ-1 HDL in vitro

    DOE PAGESBeta

    Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques; Zhu, Xuewei

    2015-07-24

    Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from themore » carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

  18. Multifunctional hybrid networks based on self assembling peptide sequences

    NASA Astrophysics Data System (ADS)

    Sathaye, Sameer

    The overall aim of this dissertation is to achieve a comprehensive correlation between the molecular level changes in primary amino acid sequences of amphiphilic beta-hairpin peptides and their consequent solution-assembly properties and bulk network hydrogel behavior. This has been accomplished using two broad approaches. In the first approach, amino acid substitutions were made to peptide sequence MAX1 such that the hydrophobic surfaces of the folded beta-hairpins from the peptides demonstrate shape specificity in hydrophobic interactions with other beta-hairpins during the assembly process, thereby causing changes to the peptide nanostructure and bulk rheological properties of hydrogels formed from the peptides. Steric lock and key complementary hydrophobic interactions were designed to occur between two beta-hairpin molecules of a single molecule, LNK1 during beta-sheet fibrillar assembly of LNK1. Experimental results from circular dichroism, transmission electron microscopy and oscillatory rheology collectively indicate that the molecular design of the LNK1 peptide can be assigned the cause of the drastically different behavior of the networks relative to MAX1. The results indicate elimination or significant reduction of fibrillar branching due to steric complementarity in LNK1 that does not exist in MAX1, thus supporting the original hypothesis. As an extension of the designed steric lock and key complementarity between two beta-hairpin molecules of the same peptide molecule. LNK1, three new pairs of peptide molecules LP1-KP1, LP2-KP2 and LP3-KP3 that resemble complementary 'wedge' and 'trough' shapes when folded into beta-hairpins were designed and studied. All six peptides individually and when blended with their corresponding shape complement formed fibrillar nanostructures with non-uniform thickness values. Loose packing in the assembled structures was observed in all the new peptides as compared to the uniform tight packing in MAX1 by SANS analysis. This

  19. Social variables exert selective pressures in the evolution and form of primate mimetic musculature.

    PubMed

    Burrows, Anne M; Li, Ly; Waller, Bridget M; Micheletta, Jerome

    2016-04-01

    Mammals use their faces in social interactions more so than any other vertebrates. Primates are an extreme among most mammals in their complex, direct, lifelong social interactions and their frequent use of facial displays is a means of proximate visual communication with conspecifics. The available repertoire of facial displays is primarily controlled by mimetic musculature, the muscles that move the face. The form of these muscles is, in turn, limited by and influenced by phylogenetic inertia but here we use examples, both morphological and physiological, to illustrate the influence that social variables may exert on the evolution and form of mimetic musculature among primates. Ecomorphology is concerned with the adaptive responses of morphology to various ecological variables such as diet, foliage density, predation pressures, and time of day activity. We present evidence that social variables also exert selective pressures on morphology, specifically using mimetic muscles among primates as an example. Social variables include group size, dominance 'style', and mating systems. We present two case studies to illustrate the potential influence of social behavior on adaptive morphology of mimetic musculature in primates: (1) gross morphology of the mimetic muscles around the external ear in closely related species of macaque (Macaca mulatta and Macaca nigra) characterized by varying dominance styles and (2) comparative physiology of the orbicularis oris muscle among select ape species. This muscle is used in both facial displays/expressions and in vocalizations/human speech. We present qualitative observations of myosin fiber-type distribution in this muscle of siamang (Symphalangus syndactylus), chimpanzee (Pan troglodytes), and human to demonstrate the potential influence of visual and auditory communication on muscle physiology. In sum, ecomorphologists should be aware of social selective pressures as well as ecological ones, and that observed morphology might

  20. A platelet-mimetic paradigm for metastasis-targeted nanomedicine platforms.

    PubMed

    Modery-Pawlowski, Christa L; Master, Alyssa M; Pan, Victor; Howard, Gregory P; Sen Gupta, Anirban

    2013-03-11

    There is compelling evidence that, beyond their traditional role in hemostasis and thrombosis, platelets play a significant role in mediating hematologic mechanisms of tumor metastasis by directly and indirectly interacting with pro-metastatic cancer cells. With this rationale, we hypothesized that platelets can be an effective paradigm to develop nanomedicine platforms that utilize platelet-mimetic interaction mechanisms for targeted diagnosis and therapy of metastatic cancer cells. Here we report on our investigation of the development of nanoconstructs that interact with metastatic cancer cells via platelet-mimetic heteromultivalent ligand-receptor pathways. For our studies, pro-metastatic human breast cancer cell line MDA-MB-231 was studied for its surface expression of platelet-interactive receptors, in comparison to another low-metastatic human breast cancer cell line, MCF-7. Certain platelet-interactive receptors were found to be significantly overexpressed on the MDA-MB-231 cells, and these cells showed significantly enhanced binding interactions with active platelets compared to MCF-7 cells. Based upon these observations, two specific receptor interactions were selected, and corresponding ligands were engineered onto the surface of liposomes as model nanoconstructs, to enable platelet-mimetic binding to the cancer cells. Our model platelet-mimetic liposomal constructs showed enhanced targeting and attachment of MDA-MB-231 cells compared to the MCF-7 cells. These results demonstrate the promise of utilizing platelet-mimetic constructs in modifying nanovehicle constructs for metastasis-targeted drug as well as modifying surfaces for ex-vivo cell enrichment diagnostic technologies. PMID:23360320

  1. A Platelet-Mimetic Paradigm for Metastasis-Targeted Nanomedicine Platforms

    PubMed Central

    Modery-Pawlowski, Christa L.; Master, Alyssa M.; Pan, Victor; Howard, Gregory; Gupta, Anirban Sen

    2013-01-01

    There is compelling evidence that beyond their traditional role in hemostasis and thrombosis, platelets play a significant role in mediating hematologic mechanisms of tumor metastasis by directly and indirectly interacting with pro-metastatic cancer cells. With this rationale, we hypothesized that platelets can be an effective paradigm to develop nanomedicine platforms that utilize platelet-mimetic interaction mechanisms for targeted diagnosis and therapy of metastatic cancer cells. Here we report on our investigation of the development of nanoconstructs that interact with metastatic cancer cells via platelet-mimetic heteromultivalent ligand-receptor pathways. For our studies, pro-metastatic human breast cancer cell line MDA-MB-231 was studied for its surface expression of platelet-interactive receptors, in comparison to another low-metastatic human breast cancer cell line, MCF-7. Certain platelet-interactive receptors were found to be significantly over-expressed on the MDA-MB-231 cells and these cells showed significantly enhanced binding interactions with active platelets compared to MCF-7 cells. Based upon these observations, two specific receptor interactions were selected and corresponding ligands were engineered onto the surface of liposomes as model nanoconstructs, to enable platelet-mimetic binding to the cancer cells. Our model platelet-mimetic liposomal constructs showed enhanced targeting and attachment of MDA-MB-231 cells compared to the MCF-7 cells. These results demonstrate the promise of utilizing platelet-mimetic constructs in modifying nanovehicle constructs for metastasis-targeted drug as well as modifying surfaces for ex-vivo cell enrichment diagnostic technologies. PMID:23360320

  2. C-Peptide Test

    MedlinePlus

    ... C-peptide is a useful marker of insulin production. The following are some purposes of C-peptide ... it nearly impossible to directly evaluate endogenous insulin production. In these cases, C-peptide measurement is a ...

  3. Replacement of the Disulfide Bridge in a KLK3-Stimulating Peptide Using Orthogonally Protected Building Blocks

    PubMed Central

    2013-01-01

    Peptide “B-2”, which is one of the most potent kallikrein-related peptidase 3 (KLK3)-stimulating compounds, consists of 12 amino acids and is cyclized by a disulfide bridge between the N- and C-terminal cysteines. Orthogonally protected building blocks were used in the peptide synthesis to introduce a disulfide bridge mimetic consisting of four carbon atoms. The resulting pseudopeptides with alkane and E-alkene linkers doubled the proteolytic activity of KLK3 at a concentration of 14 μM. They were almost as potent as the parent “B-2” peptide, which gives a 3.6-fold increase in the proteolytic activity of KLK3 at the same concentration. PMID:24900791

  4. Dissecting Electrostatic Contributions to Folding and Self-Assembly Using Designed Multicomponent Peptide Systems.

    PubMed

    Parmar, Avanish S; James, Jose K; Grisham, Daniel R; Pike, Douglas H; Nanda, Vikas

    2016-04-01

    We investigate formation of nano- to microscale peptide fibers and sheets where assembly requires association of two distinct collagen mimetic peptides (CMPs). The multicomponent nature of these designs allows the decoupling of amino acid contributions to peptide folding versus higher-order assembly. While both arginine and lysine containing CMP sequences can favor triple-helix folding, only arginine promotes rapid supramolecular assembly in each of the three two-component systems examined. Unlike lysine, the polyvalent guanidyl group of arginine is capable of both intra- and intermolecular contacts, promoting assembly. This is consistent with the supramolecular diversity of CMP morphologies observed throughout the literature. It also connects CMP self-assembly with a broad range of biomolecular interaction phenomena, providing general principles for modeling and design. PMID:26966815

  5. Water-Floating Giant Nanosheets from Helical Peptide Pentamers

    NASA Astrophysics Data System (ADS)

    Lee, Jaehun; Nam, Ki Tae

    One of the important challenges in the development of protein-mimetic materials is to understand the sequence specific assembly behavior and the dynamic folding change. Conventional strategies to construct two dimensional nanostructures from the peptides have been limited to beta-sheet forming sequences in use of basic building blocks because of their natural tendency to form sheet like aggregations. Here we identified a new peptide sequence, YFCFY that can form dimers by the disulfide bridge, fold into helix and assemble into macroscopic flat sheet at the air/water interface. Because of large driving force for two dimensional assembly and high elastic modulus of the resulting sheet, the peptide assembly induces the flattening of initially round water droplet. Additionally, we found that stabilization of helix by the dimerization is a key determinant for maintaining macroscopic flatness over a few tens centimeter even with a uniform thickness below 10 nm. Furthermore, the capability to transfer 2D film from water droplet to other substrates allows for the multiple stacking of 2D peptide nanostructure, suggesting possible applications in the biomimetic catalysts, biosensor and 2D related electronic devices. This work was supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-MA1401-01.

  6. Synthesis of Nonequilibrium Supramolecular Peptide Polymers on a Microfluidic Platform.

    PubMed

    Mason, Thomas O; Michaels, Thomas C T; Levin, Aviad; Gazit, Ehud; Dobson, Christopher M; Buell, Alexander K; Knowles, Tuomas P J

    2016-08-01

    The self-assembly of peptides and peptide mimetics into supramolecular polymers has been established in recent years as a route to biocompatible nanomaterials with novel mechanical, optical, and electronic properties. The morphologies of the resulting polymers are usually dictated by the strengths as well as lifetimes of the noncovalent bonds that lead to the formation of the structures. Together with an often incomplete understanding of the assembly mechanisms, these factors limit the control over the formation of polymers with tailored structures. Here, we have developed a microfluidic flow reactor to measure growth rates directly and accurately on the axial and radial faces of crystalline peptide supramolecular polymers. We show that the structures grow through two-dimensional nucleation mechanisms, with rates that depend exponentially on the concentration of soluble peptide. Using these mechanistic insights into the growth behavior of the axial and radial faces, we have been able to tune the aspect ratio of populations of dipeptide assemblies. These results demonstrate a general strategy to control kinetically self-assembly beyond thermodynamic products governed by the intrinsic properties of the building blocks in order to attain the required morphology and function. PMID:27387359

  7. The role of GLP-1 mimetics and basal insulin analogues in type 2 diabetes mellitus: guidance from studies of liraglutide

    PubMed Central

    Barnett, A H

    2012-01-01

    In people with type 2 diabetes mellitus (T2DM), the incretin effect is reduced, but the recent advent of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide (GLP)-1 agonists/analogues has enabled restoration of at least some of the function of the incretin system, with accompanying improvements in glycaemic control. Two GLP-1 receptor agonists/analogues are currently approved for the treatment of T2DM—exenatide (Byetta®, Eli Lilly & Co., Indianapolis, IN, US) and liraglutide (Victoza®, Novo Nordisk, Bagsvaerd, Denmark); a once-weekly formulation of exenatide (Bydureon®, Eli Lilly & Co.) has also been approved by the European Medicines Agency. The National Institute for Health and Clinical Excellence (NICE) has recently published guidance on the use of liraglutide in T2DM, based on evidence from the Liraglutide Effect and Action in Diabetes (LEAD) Phase III trial programme, which compared liraglutide with existing glucose-lowering therapies, such as exenatide and insulin glargine. The LEAD programme reported HbA1c reductions from 0.8 to 1.5% with liraglutide (1.2 and 1.8 mg), accompanied by low rates of hypoglycaemia and some weight loss; side effects were primarily gastrointestinal in nature (e.g. nausea and diarrhoea). Based on the findings of the LEAD studies and the NICE recommendation, liraglutide now represents an important therapy widely available in the UK for certain patient groups, including those with a body mass index (BMI) ≥35.0 kg/m2, and patients with a BMI <35 kg/m2 who are considered unsuitable for insulin and are failing to meet targets for glycaemic control with oral agents. NICE guidelines still suggest that most patients without considerable obesity (BMI <35 kg/m2) are probably best managed using insulin therapy. Evidence also suggests a future role for GLP-1 mimetics in combination with basal insulin. PMID:22051096

  8. Fluorescence Correlation Spectroscopy Reveals Highly Efficient Cytosolic Delivery of Certain Penta-Arg Proteins and Stapled Peptides

    PubMed Central

    Steinauer, Angela; Rhoades, Elizabeth; Schepartz, Alanna

    2015-01-01

    We used fluorescence correlation spectroscopy (FCS) to accurately and precisely determine the relative efficiencies with which three families of “cell-penetrating peptides” traffic to the cytosol of mammalian cells. We find that certain molecules containing a “penta-arg” motif reach the cytosol, intact, with efficiencies greater than 50%. This value is at least 10-fold higher than that observed for the widely studied cationic sequence derived from HIV Tat or polyarginine Arg8, and equals that of hydrocarbon-stapled peptides that are active in cells and animals. Moreover, we show that the efficiency with which stapled peptides reach the cytosol, as determined by FCS, correlates directly with their efficacy in cell-based assays. We expect that these findings and the associated technology will aid the design of peptides, proteins, and peptide mimetics that predictably and efficiently reach the interior of mammalian cells. PMID:25679876

  9. Design of Compact Biomimetic Cellulose Binding Peptides as Carriers for Cellulose Catalytic Degradation.

    PubMed

    Khazanov, Netaly; Iline-Vul, Taly; Noy, Efrat; Goobes, Gil; Senderowitz, Hanoch

    2016-01-21

    The conversion of biomass into biofuels can reduce the strategic vulnerability of petroleum-based systems and at the same time have a positive effect on global climate issues. Lignocellulose is the cheapest and most abundant source of biomass and consequently has been widely considered as a source for liquid fuel. However, despite ongoing efforts, cellulosic biofuels are still far from commercial realization, one of the major bottlenecks being the hydrolysis of cellulose into simpler sugars. Inspired by the structural and functional modularity of cellulases used by many organisms for the breakdown of cellulose, we propose to mimic the cellulose binding domain (CBD) and the catalytic domain of these proteins by small molecular entities. Multiple copies of these mimics could subsequently be tethered together to enhance hydrolytic activity. In this work, we take the first step toward achieving this goal by applying computational approaches to the design of efficient, cost-effective mimetics of the CBD. The design is based on low molecular weight peptides that are amenable to large-scale production. We provide an optimized design of four short (i.e., ∼18 residues) peptide mimetics based on the three-dimensional structure of a known CBD and demonstrate that some of these peptides bind cellulose as well as or better than the full CBD. The structures of these peptides were studied by circular dichroism and their interactions with cellulose by solid phase NMR. Finally, we present a computational strategy for predicting CBD/peptide-cellulose binding free energies and demonstrate its ability to provide values in good agreement with experimental data. Using this computational model, we have also studied the dissociation pathway of the CBDs/peptides from the surface of cellulose. PMID:26691055

  10. Triple-enzyme mimetic activity of nickel-palladium hollow nanoparticles and their application in colorimetric biosensing of glucose.

    PubMed

    Wang, Qingqing; Zhang, Lingling; Shang, Changshuai; Zhang, Zhiquan; Dong, Shaojun

    2016-04-01

    We demonstrate that nickel-palladium hollow nanoparticles (NiPd hNPs) exhibit triple-enzyme mimetic activity: oxidase-like activity, peroxidase-like activity and catalase-like activity. As peroxidase mimetics, the catalytic activity of NiPd hNPs was investigated in detail. On this basis, a simple glucose biosensor with a wide linear range and low detection limit was developed. PMID:27009927

  11. Photochemical solar energy conversion utilizing semiconductors localized in membrane-mimetic systems. Performance report, April 1, 1989--August 31, 1991

    SciTech Connect

    Fendler, J.H.

    1991-08-31

    Extending the frontiers of colloidal photochemistry and colloidal electrochemistry to solar photochemistry research had been the main objective of this research. More specific objectives of this proposal include the examination of semiconductor-particle-mediated photoelectron transfer and photoelectric effects in different membrane mimetic systems. Emphasis had been placed on developing bilayer lipid membranes and Langmuir-Blodgett films as new membrane-mimetic systems, as well as on the characterization and utilization of these systems.

  12. The contribution of skin antimicrobial peptides to the system of innate immunity in anurans.

    PubMed

    Conlon, J Michael

    2011-01-01

    Cationic peptides with the propensity to adopt an amphipathic α-helical conformation in a membrane-mimetic environment are synthesized in the skins of many species of anurans (frogs and toads). These peptides frequently display cytolytic activities against a range of pathogenic bacteria and fungi consistent with the idea that they play a role in the host's system of innate immunity. However, the importance of the peptides in the survival strategy of the animal is not clearly understood. It is a common misconception that antimicrobial peptides are synthesized in the skins of all anurans. In fact, the species distribution is sporadic suggesting that their production may confer some evolutionary advantage to the organism but is not necessary for survival. Although growth inhibitory activity against the chytrid fungus Batrachochytrium dendrobatidis, responsible for anuran population declines worldwide, has been demonstrated in vitro, the ability of frog skin antimicrobial peptides to protect the animal in the wild appears to be limited and there is no clear correlation between their production by a species and its resistance to fatal chytridiomycosis. The low potency of many frog skin antimicrobial peptides is consistent with the hypothesis that cutaneous symbiotic bacteria may provide the major system of defense against pathogenic microorganisms in the environment with antimicrobial peptides assuming a supplementary role in some species. PMID:20640445

  13. What kind of signals do mimetic tiger moths send? A phylogenetic test of wasp mimicry systems (Lepidoptera: Arctiidae: Euchromiini).

    PubMed Central

    Simmons, Rebecca B; Weller, Susan J

    2002-01-01

    Mimicry has been examined in field and laboratory studies of butterflies and its evolutionary dynamics have been explored in computer simulations. Phylogenetic studies examining the evolution of mimicry, however, are rare. Here, the phylogeny of wasp-mimicking tiger moths, the Sphecosoma group, was used to test evolutionary predictions of computer simulations of conventional Müllerian mimicry and quasi-Batesian mimicry dynamics. We examined whether mimetic traits evolved individually, or as suites of characters, using concentrated change tests. The phylogeny of these moth mimics revealed that individual mimetic characters were conserved, as are the three mimetic wasp forms: yellow Polybia, black Polybia and Parachartergus mimetic types. This finding was consistent with a 'supergene' control of linked loci and the Nicholson two-step model of mimicry evolution. We also used a modified permutation-tail probability approach to examine the rate of mimetic-type evolution. The observed topology, hypothetical Müllerian and Batesian scenarios, and 1000 random trees were compared using Kishino-Hasegawa tests. The observed phylogeny was more consistent with the predicted Müllerian distribution of mimetic traits than with that of a quasi-Batesian scenario. We suggest that the range of discriminatory abilities of the predator community plays a key role in shaping mimicry dynamics. PMID:12028753

  14. Targeting diverse protein–protein interaction interfaces with α/β-peptides derived from the Z-domain scaffold

    SciTech Connect

    Checco, James W.; Kreitler, Dale F.; Thomas, Nicole C.; Belair, David G.; Rettko, Nicholas J.; Murphy, William L.; Forest, Katrina T.; Gellman, Samuel H.

    2015-04-14

    Peptide-based agents derived from well-defined scaffolds offer an alternative to antibodies for selective and high-affinity recognition of large and topologically complex protein surfaces. Here, we describe a strategy for designing oligomers containing both α- and β-amino acid residues ("α/β-peptides") that mimic several peptides derived from the three-helix bundle "Z-domain" scaffold. We show that α/β-peptides derived from a Z-domain peptide targeting vascular endothelial growth factor (VEGF) can structurally and functionally mimic the binding surface of the parent peptide while exhibiting significantly decreased susceptibility to proteolysis. The tightest VEGF-binding α/β-peptide inhibits the VEGF₁₆₅-induced proliferation of human umbilical vein endothelial cells. We demonstrate the versatility of this strategy by showing how principles underlying VEGF signaling inhibitors can be rapidly extended to produce Z-domain–mimetic α/β-peptides that bind to two other protein partners, IgG and tumor necrosis factor-α. Because well-established selection techniques can identify high-affinity Z-domain derivatives from large DNA-encoded libraries, our findings should enable the design of biostable α/β-peptides that bind tightly and specifically to diverse targets of biomedical interest. Such reagents would be useful for diagnostic and therapeutic applications.

  15. Design, Synthesis, and Validation of a β-Turn Mimetic Library Targeting Protein–Protein and Peptide–Receptor Interactions

    PubMed Central

    Whitby, Landon R.; Ando, Yoshio; Setola, Vincent; Vogt, Peter K.; Roth, Bryan L.; Boger, Dale L.

    2011-01-01

    The design and synthesis of a β-turn mimetic library as a key component of a small molecule library targeting the major recognition motifs involved in protein–protein interactions is described. Analysis of a geometric characterization of 10,245 β-turns in the protein data bank (PDB) suggested that trans-pyrrolidine-3,4-dicarboxamide could serve as an effective and synthetically accessible library template. This was confirmed by initially screening select compounds against a series of peptide-activated GPCRs that recognize a β-turn structure in their endogenous ligands. This validation study was highlighted by identification of both nonbasic and basic small molecules with high affinities (Ki = 390 nM and 23 nM, respectively) for the κ-opioid receptor (KOR). Consistent with the screening capabilities of collaborators and following the design validation, the complete library was assembled as 210 mixtures of 20 compounds, providing a total of 4,200 compounds designed to mimic all possible permutations of 3 of the 4 residues in a naturally occurring β-turn. Unique to the design and because of the C2 symmetry of the template, a typical 20 × 20 × 20-mix (8,000 compounds prepared as 400 mixtures of 20 compounds) needed to represent 20 variations in the side chains of three amino acid residues reduces to a 210 × 20-mix, thereby simplifying the library synthesis and subsequent screening. The library was prepared using a solution-phase synthetic protocol with liquid–liquid or liquid–solid extractions for purification and conducted on a scale that insures its long-term availability for screening campaigns. Screening the library against the human opioid receptors (KOR, MOR, and DOR) identified not only the activity of library members expected to mimic the opioid receptor peptide ligands, but also additional side chain combinations that provided enhanced receptor binding selectivities (>100-fold) and affinities (as low as Ki = 80 nM for KOR). A key insight to

  16. Biphasic effects of direct, but not indirect, GABA mimetics and antagonists on haloperidol-induced catalepsy.

    PubMed

    Worms, P; Lloyd, K G

    1980-03-01

    At very low doses the GABA agonists SL 76002 and muscimol diminish haloperidol-induced catalepsy. At somewhat higher doses these compounds potentiate catalepsy. Biphasic effects on DA-receptor mediated functions have previously been noted with bicuculline and picrotoxinin. In contrast, manipulation of GABA levels by enzyme inhibition induced only a monophasic effect on dopamine-mediated behaviour. The potentiation of GABA levels by enzyme inhibition induced only a monophasic effect on dopamine-mediated behaviour. The potentiation of haloperidol-induced catalepsy by GABA mimetics is also observed with dipropylacetate, delta-aminovaleric acid and gamma-acetylenic GABA. This GABA-mimetic potentiation of catakepsy was blocked by the coadministration of bicuculline. These results confirm and extend the hypothesis that GABA-neurons influence DA neuron function. Furthermore they suggest that more than one group of GABA receptors influence directly and/or indirectly DA neuronal function, with different resultant effects. PMID:7189827

  17. Hemoglobin-mimetic oxygen adsorbent prepared via self-assembly of cysteinyl bolaamphiphiles.

    PubMed

    Lee, Chaemyeong; Kim, Min-Chul; Lee, Sang-Yup

    2016-06-01

    In this study, a novel cysteinyl bolaamphiphilic molecule was synthesized and its self-assembled planar suprastructure was applied as a biomimetic matrix to create a hemoglobin-mimetic oxygen adsorbent that exploits the ability of cysteine thiols to bind hemin. Self-assembly of the cysteinyl bolaamphiphilic molecule exposed cysteine thiols on its surface in the presence of β-mercaptoethanol, known to reduce disulfide bonds, without which, helically coiled structures were generated. The self-assembled planar structure was used as a soft matrix to create a hemoglobin-mimetic oxygen adsorbent. The surface-exposed cysteine thiols were used to attach hemin, producing a hemin-bound, planar structure mimicking hemoglobin. This hemoglobin mimic strongly adsorbed oxygen and remained stable up to 50°C. The cysteinyl bolaamphiphile self-assembled structure provided a biomimetic platform that allowed for the association of biological substances in a manner similar to natural proteins. PMID:26970824

  18. The aerodynamic costs of warning signals in palatable mimetic butterflies and their distasteful models.

    PubMed Central

    Srygley, Robert B.

    2004-01-01

    Bates hypothesized that some butterfly species that are palatable gain protection from predation by appearing similar to distasteful butterflies. When undisturbed, distasteful butterflies fly slowly and in a straight line, and palatable Batesian mimics also adopt this nonchalant behaviour. When seized by predators, distasteful butterflies are defended by toxic or nauseous chemicals. Lacking chemical defences, Batesian mimics depend on flight to escape attacks. Here, I demonstrate that flight in warning-coloured mimetic butterflies and their distasteful models is more costly than in closely related non-mimetic butterflies. The increased cost is the result of differences in both wing shape and kinematics. Batesian mimics and their models slow the angular velocity of their wings to enhance the colour signal but at an aerodynamic cost. Moreover, the design for flight in Batesian mimics has an additional energetic cost over that of its models. The added cost may cause Batesian mimics to be rare, explaining a general pattern that Bates first observed. PMID:15156916

  19. Recognition of Smac-mimetic compounds by the BIR domain of cIAP1

    PubMed Central

    Cossu, Federica; Malvezzi, Francesca; Canevari, Giulia; Mastrangelo, Eloise; Lecis, Daniele; Delia, Domenico; Seneci, Pierfausto; Scolastico, Carlo; Bolognesi, Martino; Milani, Mario

    2010-01-01

    Inhibitor of apoptosis proteins (IAPs) are negative regulators of apoptosis. As IAPs are overexpressed in many tumors, where they confer chemoresistance, small molecules inactivating IAPs have been proposed as anticancer agents. Accordingly, a number of IAP-binding pro-apoptotic compounds that mimic the sequence corresponding to the N-terminal tetrapeptide of Smac/DIABLO, the natural endogenous IAPs inhibitor, have been developed. Here, we report the crystal structures of the BIR3 domain of cIAP1 in complex with Smac037, a Smac-mimetic known to bind potently to the XIAP-BIR3 domain and to induce degradation of cIAP1, and in complex with the novel Smac-mimetic compound Smac066. Thermal stability and fluorescence polarization assays show the stabilizing effect and the high affinity of both Smac037 and Smac066 for cIAP1- and cIAP2-BIR3 domains. PMID:20954235

  20. Mimetic Theory for Cell-Centered Lagrangian Finite Volume Formulation on General Unstructured Grids

    SciTech Connect

    Sambasivan, Shiv Kumar; Shashkov, Mikhail J.; Burton, Donald E.; Christon, Mark A.

    2012-07-19

    A finite volume cell-centered Lagrangian scheme for solving large deformation problems is constructed based on the hypo-elastic model and using the mimetic theory. Rigorous analysis in the context of gas and solid dynamics, and arbitrary polygonal meshes, is presented to demonstrate the ability of cell-centered schemes in mimicking the continuum properties and principles at the discrete level. A new mimetic formulation based gradient evaluation technique and physics-based, frame independent and symmetry preserving slope limiters are proposed. Furthermore, a physically consistent dissipation model is employed which is both robust and inexpensive to implement. The cell-centered scheme along with these additional new features are applied to solve solids undergoing elasto-plastic deformation.

  1. Differential effects of superoxide dismutase and superoxide dismutase/catalase mimetics on human breast cancer cells.

    PubMed

    Shah, Manisha H; Liu, Guei-Sheung; Thompson, Erik W; Dusting, Gregory J; Peshavariya, Hitesh M

    2015-04-01

    Reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H2O2) have been implicated in development and progression of breast cancer. In the present study, we have evaluated the effects of the superoxide dismutase (SOD) mimetic MnTmPyP and the SOD/catalase mimetic EUK 134 on superoxide and H2O2 formation as well as proliferation, adhesion, and migration of MCF-7 and MDA-MB-231 cells. Superoxide and H2O2 production was examined using dihydroethidium and Amplex red assays, respectively. Cell viability and adhesion were measured using a tetrazolium-based MTT assay. Cell proliferation was determined using trypan blue assay. Cell cycle progression was analyzed using flow cytometry. Clonal expansion of a single cell was performed using a colony formation assay. Cell migration was measured using transwell migration assay. Dual luciferase assay was used to determine NF-κB reporter activity. EUK 134 effectively reduced both superoxide and H2O2, whereas MnTmPyP removed superoxide but enhanced H2O2 formation. EUK 134 effectively attenuated viability, proliferation, clonal expansion, adhesion, and migration of MCF-7 and MDA-MB-231 cells. In contrast, MnTmPyP only reduced clonal expansion of MCF-7 and MDA-MB-231 cells but had no effect on adhesion and cell cycle progression. Tumor necrosis factor-alpha-induced NF-κB activity was reduced by EUK 134, whereas MnTmPyP enhanced this activity. These data indicate that the SOD mimetic MnTmPyP and the SOD/catalase mimetic EUK 134 exert differential effects on breast cancer cell growth. Inhibition of H2O2 signaling using EUK 134-like compound might be a promising approach to breast cancer therapy. PMID:25794772

  2. Mimetic F(R) inflation confronted with Planck and BICEP2/Keck Array data

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-05-01

    In this paper we demonstrate that in the context of mimetic F(R) gravity with Lagrange multiplier, it is possible to realize cosmologies which are compatible with the recent BICEP2/Keck Array data. We provide some characteristic examples for which the predicted scalar to tensor ratio can be quite smaller in comparison to the upper limit imposed by the BICEP2/Keck Array observations.

  3. The Role of BH3-Mimetic Drugs in the Treatment of Pediatric Hepatoblastoma

    PubMed Central

    Lieber, Justus; Armeanu-Ebinger, Sorin; Fuchs, Jörg

    2015-01-01

    Pediatric hepatoblastoma (HB) is commonly treated by neoadjuvant chemotherapy and surgical tumor resection according to international multicenter trial protocols. Complete tumor resection is essential and survival rates up to 95% have now been achieved in those tumors classified as standard-risk HB. Drug resistance and occurrence of metastases remain the major challenges in the treatment of HB, especially in high-risk tumors. These conditions urgently require the development of alternative therapeutic strategies. One of those alternatives is the modulation of apoptosis in HB cells. HBs regularly overexpress anti-apoptotic proteins of the Bcl-family in comparison to healthy liver tissue. This fact may contribute to the development of chemoresistance of HB cells. Synthetic small inhibitory molecules with BH3-mimetic effects, such as ABT-737 and obatoclax, enhance the susceptibility of tumor cells to different cytotoxic drugs and thereby affect initiator proteins of the apoptosis cascade via the intrinsic pathway. Besides additive effects on HB cell viability when used in combination with cytotoxic drugs, BH3-mimetics also play a role in preventing metastasation by reducing adhesion and inhibiting cell migration abilities. Presumably, including additive BH3-mimetic drugs into existing therapeutic regimens in HB patients might allow dose reduction of established cytotoxic drugs and thereby associated immanent side effects, while maintaining the antitumor activity. Furthermore, reduction of tumor growth and inhibition of tumor cell dissemination may facilitate complete surgical tumor resection, which is mandatory in this tumor type resulting in improved survival rates in high-risk HB. Currently, there are phase I and phase II clinical trials in several cancer entities using this potential target. This paper reviews the available literature regarding the use of BH3-mimetic drugs as single agents or in combination with chemotherapy in various malignancies and focuses on

  4. Alkaloid defenses of co-mimics in a putative Müllerian mimetic radiation

    PubMed Central

    2014-01-01

    Background Polytypism in aposematic species is unlikely according to theory, but commonly seen in nature. Ranitomeya imitator is a poison frog species exhibiting polytypic mimicry of three congeneric model species (R. fantastica, R. summersi, and two morphs of R. variabilis) across four allopatric populations (a "mimetic radiation"). In order to investigate chemical defenses in this system, a key prediction of Müllerian mimicry, we analyzed the alkaloids of both models and mimics from four allopatric populations. Results In this study we demonstrate distinct differences in alkaloid profiles between co-mimetic species within allopatric populations. We further demonstrate that R. imitator has a greater number of distinct alkaloid types than the model species and more total alkaloids in all but one population. Conclusions Given that R. imitator is the more abundant species in these populations, R. imitator is likely driving the majority of predator-learned avoidance in these complexes. The success of Ranitomeya imitator as a putative advergent mimic may be a direct result of differences in alkaloid sequestration. Furthermore, we propose that automimicry within co-mimetic species is an important avenue of research. PMID:24707851

  5. Modified Gauss-Bonnet gravity with the Lagrange multiplier constraint as mimetic theory

    NASA Astrophysics Data System (ADS)

    Astashenok, Artyom V.; Odintsov, Sergei D.; Oikonomou, V. K.

    2015-09-01

    In this paper we propose and extensively study mimetic f({G}) modified gravity models, with various scenarios of cosmological evolution, with or without extra matter fluids. The easiest formulation is based on the use of the Lagrange multiplier constraint. In certain versions of this theory, it is possible to realize accelerated expansion of the Universe or even unified evolution, which includes inflation with dark energy, and at the same time in the same theoretical framework, dark matter is described by the theory. This is achieved by the re-parametrization of the metric tensor, which introduces a new degree of freedom in the cosmological equations and leads to the appearance of the mimetic ‘dark matter’ component. In the context of the mimetic f({G}) theory, we also provide some quite general reconstruction schemes, which enable us to find which f({G}) gravity generates a specific cosmological evolution. In addition, we also provide the general reconstruction technique for the Lagrange multiplier f({G}) gravity. All our results are accompanied by illustrative examples, with special emphasis on bouncing cosmologies.

  6. SOD mimetic activity and antiproliferative properties of a novel tetra nuclear copper (II) complex.

    PubMed

    Weintraub, Sagiv; Moskovitz, Yoni; Fleker, Ohad; Levy, Ariel R; Meir, Aviv; Ruthstein, Sharon; Benisvy, Laurent; Gruzman, Arie

    2015-12-01

    The search for novel anticancer therapeutic agents is an urgent and important issue in medicinal chemistry. Here, we report on the biological activity of the copper-based bioinorganic complex Cu4 (2,4-di-tert-butyl-6-(1H-imidazo- [1, 10] phenanthrolin-2-yl)phenol)4]·10 CH3CN (2), which was tested in rat L6 myotubes, mouse NSC-34 motor neurone-like cells, and HepG-2 human liver carcinoma. Upon 96 h incubation, 2 exhibited a significant cytotoxic effect on all three types of cells via activation of two cell death mechanisms (apoptosis and necrosis). Complex 2 exhibited better potency and efficacy than the canonical cytotoxic drug cisplatin. Moreover, during shorter incubations, complex 2 demonstrated a significant SOD mimetic activity, and it was more effective and more potent than the well-known SOD mimetic TEMPOL. In addition, complex 2 was able to interact with DNA and, cleave DNA in the presence of sodium ascorbate. This study shows the potential of using polynuclear redox active compounds for developing novel anticancer drugs through SOD-mimetic redox pathways. PMID:26547749

  7. Manipulation of health span and function by dietary caloric restriction mimetics.

    PubMed

    Roth, George S; Ingram, Donald K

    2016-01-01

    After nearly a century of rigorous investigation and testing, dietary caloric restriction (CR) remains the most robust and reproducible method for slowing aging and maintaining health, function, and vitality. This intervention has been applied to species across the evolutionary spectrum, but for a number of reasons, practical applicability to humans has been questioned. To overcome these issues, we initiated the field of CR mimetics in 1998 and have observed its development into a full-fledged antiaging industry. Basically, strategies that enable individuals to obtain the biological benefits of CR without reducing actual food intake can be considered CR mimetics, whether functional, pharmaceutical, nutraceutical, or other. Some of the best known candidates include resveratrol and related agents, the antidiabetic drug metformin, and rapamycin and other mTOR regulators. While the mechanisms of action vary, these and essentially all CR mimetic candidates work through at least some of the same pathways as actual CR. While the entire field continues to evolve rapidly, the current status will be reviewed here, with particular focus on recent developments, the most practical relevance and applicability for potential consumers, and new strategies for the future. PMID:26214681

  8. Identification of novel insulin mimetic drugs by quantitative total internal reflection fluorescence (TIRF) microscopy

    PubMed Central

    Lanzerstorfer, Peter; Stadlbauer, Verena; Chtcheglova, Lilia A; Haselgrübler, Renate; Borgmann, Daniela; Wruss, Jürgen; Hinterdorfer, Peter; Schröder, Klaus; Winkler, Stephan M; Höglinger, Otmar; Weghuber, Julian

    2014-01-01

    Background and Purpose Insulin stimulates the transport of glucose in target tissues by triggering the translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Resistance to insulin, the major abnormality in type 2 diabetes, results in a decreased GLUT4 translocation efficiency. Thus, special attention is being paid to search for compounds that are able to enhance this translocation process in the absence of insulin. Experimental Approach Total internal reflection fluorescence (TIRF) microscopy was applied to quantify GLUT4 translocation in highly insulin-sensitive CHO-K1 cells expressing a GLUT4-myc-GFP fusion protein. Key Results Using our approach, we demonstrated GLUT4 translocation modulatory properties of selected substances and identified novel potential insulin mimetics. An increase in the TIRF signal was found to correlate with an elevated glucose uptake. Variations in the expression level of the human insulin receptor (hInsR) showed that the insulin mimetics identified stimulate GLUT4 translocation by a mechanism that is independent of the presence of the hInsR. Conclusions and Implications Taken together, the results indicate that TIRF microscopy is an excellent tool for the quantification of GLUT4 translocation and for identifying insulin mimetic drugs. PMID:25039620

  9. USP11-dependent selective cIAP2 deubiquitylation and stabilization determine sensitivity to Smac mimetics.

    PubMed

    Lee, E-W; Seong, D; Seo, J; Jeong, M; Lee, H-K; Song, J

    2015-09-01

    Given their crucial role in apoptosis suppression, inhibitor of apoptosis proteins (IAPs) have recently become attractive targets for cancer therapy. Here, we report that cellular IAP2 (cIAP2) is specifically stabilized in several cancer cell lines, leading to resistance to Smac mimetics, such as BV6 and birinapant. In particular, our results showed that cIAP2 depletion, but not cIAP1 depletion, sensitized cancer cells to Smac mimetic-induced apoptosis. Ubiquitin-specific protease 11 (USP11) is a deubiquitylase that directly stabilizes cIAP2. USP11 overexpression is frequently found in colorectal cancer and melanoma and is correlated with poor survival. In our study, cancer cell lines expressing high levels of USP11 exhibited strong resistance to Smac mimetic-induced cIAP2 degradation. Furthermore, USP11 downregulation sensitized these cells to apoptosis induced by TRAIL and BV6 and suppressed tumor growth in a xenograft model. Finally, the TNFα/JNK pathway induced USP11 expression and maintained cIAP2 stability, suggesting an alternative TNFα-dependent cell survival pathway. Collectively, our data suggest that USP11-stabilized cIAP2 may serve as a barrier against IAP-targeted clinical approaches. PMID:25613375

  10. Role of phosphate on stability and catalase mimetic activity of cerium oxide nanoparticles.

    PubMed

    Singh, Ragini; Singh, Sanjay

    2015-08-01

    Cerium oxide nanoparticles (CeNPs) have been recently shown to scavenge reactive oxygen and nitrogen species (ROS and RNS) in different experimental model systems. CeNPs (3+) and CeNPs (4+) have been shown to exhibit superoxide dismutase (SOD) and catalase mimetic activity, respectively. Due to their nanoscale dimension, CeNPs are expected to interact with the components of biologically relevant buffers and medium, which could alter their catalytic properties. We have demonstrated earlier that CeNPs (3+) interact with phosphate and lose the SOD activity. However, very little is known about the interaction of CeNPs (4+) with the phosphate and other anions, predominantly present in biological buffers and their effects on the catalase mimetic-activity of these nanoparticles. In this study, we report that catalase mimetic-activity of CeNPs (4+) is resistant to the phosphate anions, pH changes and composition of cell culture media. Given the abundance of phosphate anions in the biological system, it is likely that internalized CeNPs would be influenced by cytoplasmic and nucleoplasmic concentration of phosphate. PMID:26011425

  11. Assignment of the binding site for haptoglobin on apolipoprotein A-I.

    PubMed

    Spagnuolo, Maria Stefania; Cigliano, Luisa; D'Andrea, Luca D; Pedone, Carlo; Abrescia, Paolo

    2005-01-14

    Haptoglobin (Hpt) was previously found to bind the high density lipoprotein (HDL) apolipoprotein A-I (ApoA-I) and able to inhibit the ApoA-I-dependent activity of the enzyme lecithin:cholesterol acyltransferase (LCAT), which plays a major role in the reverse cholesterol transport. The ApoA-I structure was analyzed to detect the site bound by Hpt. ApoA-I was treated by cyanogen bromide or hydroxylamine; the resulting fragments, separated by electrophoresis or gel filtration, were tested by Western blotting or enzyme-linked immunosorbent assay for their ability to bind Hpt. The ApoA-I sequence from Glu113 to Asn184 harbored the binding site for Hpt. Biotinylated peptides were synthesized overlapping such a sequence, and their Hpt binding activity was determined by avidin-linked peroxidase. The highest activity was exhibited by the peptide P2a, containing the ApoA-I sequence from Leu141 to Ala164. Such a sequence contains an ApoA-I domain required for binding cells, promoting cholesterol efflux, and stimulating LCAT. The peptide P2a effectively prevented both binding of Hpt to HDL-coated plastic wells and Hpt-dependent inhibition of LCAT, measured by anti-Hpt antibodies and cholesterol esterification activity, respectively. The enzyme activity was not influenced, in the absence of Hpt, by P2a. Differently from ApoA-I or HDL, the peptide did not compete with hemoglobin for Hpt binding in enzyme-linked immunosorbent assay experiments. The results suggest that Hpt might mask the ApoA-I domain required for LCAT stimulation, thus impairing the HDL function. Synthetic peptides, able to displace Hpt from ApoA-I without altering its property of binding hemoglobin, might be used for treatment of diseases associated with defective LCAT function. PMID:15533931

  12. Calorimetric studies of the interactions of metalloenzyme active site mimetics with zinc-binding inhibitors.

    PubMed

    Robinson, Sophia G; Burns, Philip T; Miceli, Amanda M; Grice, Kyle A; Karver, Caitlin E; Jin, Lihua

    2016-07-19

    The binding of drugs to metalloenzymes is an intricate process that involves several interactions, including binding of the drug to the enzyme active site metal, as well as multiple interactions between the drug and the enzyme residues. In order to determine the free energy contribution of Zn(2+) binding by known metalloenzyme inhibitors without the other interactions, valid active site zinc structural mimetics must be formed and binding studies need to be performed in biologically relevant conditions. The potential of each of five ligands to form a structural mimetic with Zn(2+) was investigated in buffer using Isothermal Titration Calorimetry (ITC). All five ligands formed strong 1 : 1 (ligand : Zn(2+)) binary complexes. The complexes were used in further ITC experiments to study their interaction with 8-hydroxyquinoline (8-HQ) and/or acetohydroxamic acid (AHA), two bidentate anionic zinc-chelating enzyme inhibitors. It was found that tetradentate ligands were not suitable for creating zinc structural mimetics for inhibitor binding in solution due to insufficient coordination sites remaining on Zn(2+). A stable binary complex, [Zn(BPA)](2+), which was formed by a tridentate ligand, bis(2-pyridylmethyl)amine (BPA), was found to bind one AHA in buffer or a methanol : buffer mixture (60 : 40 by volume) at pH 7.25 or one 8-HQ in the methanol : buffer mixture at pH 6.80, making it an effective structural mimetic for the active site of zinc metalloenzymes. These results are consistent with the observation that metalloenzyme active site zinc ions have three residues coordinated to them, leaving one or two sites open for inhibitors to bind. Our findings indicate that Zn(BPA)X2 can be used as an active site structural mimetic for zinc metalloenzymes for estimating the free energy contribution of zinc binding to the overall inhibitor active site interactions. Such use will help aid in the rational design of inhibitors to a variety of zinc metalloenzymes

  13. Novel apo E-derived ABCA1 agonist peptide (CS-6253) promotes reverse cholesterol transport and induces formation of preβ-1 HDL in vitro

    SciTech Connect

    Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques; Zhu, Xuewei

    2015-07-24

    Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from the carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These

  14. An Escherichia coli twin-arginine signal peptide switches between helical and unstructured conformations depending on the hydrophobicity of the environment.

    PubMed

    San Miguel, Miguel; Marrington, Rachel; Rodger, P Mark; Rodger, Alison; Robinson, Colin

    2003-08-01

    The Tat system catalyzes the transport of folded globular proteins across the bacterial plasma membrane and the chloroplast thylakoid. It recognizes cleavable signal peptides containing a critical twin-arginine motif but little is known of the overall structure of these peptides. In this report, we have analyzed the secondary structure of the SufI signal peptide, together with those of two nonfunctional variants in which the region around the twin-arginine, RRQFI, is replaced by KKQFI or RRQAA. Circular dichroism studies show that the SufI peptide exists as an unstructured peptide in aqueous solvent with essentially no stable secondary structure. In membrane-mimetic environments such as SDS micelles or water/trifluoroethanol, however, the peptide adopts a structure containing up to about 40% alpha-helical content. Secondary structure predictions and molecular modelling programs strongly suggest that the helical region begins at, or close to, the twin-arginine motif. Studies on the thermal stability of the helix demonstrate a sharp transition between the unstructured and helical states, suggesting that the peptide exists in one of two distinct states. The two nonfunctional peptides exhibit almost identical spectra and properties to the wild-type SufI peptide, indicating that it is the arginine sidechains, and not their contribution to the helical structure, that are critical in this class of peptide. PMID:12899691

  15. ApoA-1 mimetic restores adiponectin expression and insulin sensitivity independent of changes in body weight in female obese mice

    PubMed Central

    Marino, J S; Peterson, S J; Li, M; Vanella, L; Sodhi, K; Hill, J W; Abraham, N G

    2012-01-01

    Background: We examined the ability of the apolipoprotein AI mimetic peptide L-4F to improve the metabolic state of female and male ob mice and the mechanisms involved. Methods: Female and male lean and obese (ob) mice were administered L-4F or vehicle for 6 weeks. Body weight was measured weekly. Fat distribution, serum cytokines and markers of cardiovascular dysfunction were determined at the end of treatment. Results: L-4F significantly decreased serum interleukin (IL)-6, tumor necrosis factor-α and IL-1β. L-4F improved vascular function, and increased serum adiponectin levels and insulin sensitivity compared with untreated mice. In addition, L-4F treatment increased heme oxygenase (HO)-1, pAKT and pAMPK levels in kidneys of ob animals. pAKT and pAMPK levels were significantly reduced in the presence of an HO inhibitor. Interestingly, L4F did not alter body weight in female mice, but caused a significant reduction in males. Conclusions: L-4F treatments reduced cardiovascular risk factors and improved insulin sensitivity in female ob mice independent of body fat changes. Reduced inflammatory cytokine levels accompanied by increased HO activity, serum adiponectin and improved insulin sensitivity suggest that L-4F may promote the conversion of visceral fat to a healthier phenotype. Therefore, L-4F appears to be a promising therapeutic strategy for treating both cardiovascular risk factors and insulin resistance in obese patients of either gender. PMID:23169576

  16. Bio-mimetic Nanostructure Self-assembled from Au@Ag Heterogeneous Nanorods and Phage Fusion Proteins for Targeted Tumor Optical Detection and Photothermal Therapy

    PubMed Central

    Wang, Fei; Liu, Pei; Sun, Lin; Li, Cuncheng; Petrenko, Valery A.; Liu, Aihua

    2014-01-01

    Nanomaterials with near-infrared (NIR) absorption have been widely studied in cancer detection and photothermal therapy (PTT), while it remains a great challenge in targeting tumor efficiently with minimal side effects. Herein we report a novel multifunctional phage-mimetic nanostructure, which was prepared by layer-by-layer self-assembly of Au@Ag heterogenous nanorods (NRs) with rhodamine 6G, and specific pVIII fusion proteins. Au@Ag NRs, first being applied for PTT, exhibited excellent stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm2. The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor. PMID:25348392

  17. Bio-mimetic Nanostructure Self-assembled from Au@Ag Heterogeneous Nanorods and Phage Fusion Proteins for Targeted Tumor Optical Detection and Photothermal Therapy

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Liu, Pei; Sun, Lin; Li, Cuncheng; Petrenko, Valery A.; Liu, Aihua

    2014-10-01

    Nanomaterials with near-infrared (NIR) absorption have been widely studied in cancer detection and photothermal therapy (PTT), while it remains a great challenge in targeting tumor efficiently with minimal side effects. Herein we report a novel multifunctional phage-mimetic nanostructure, which was prepared by layer-by-layer self-assembly of Au@Ag heterogenous nanorods (NRs) with rhodamine 6G, and specific pVIII fusion proteins. Au@Ag NRs, first being applied for PTT, exhibited excellent stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm2. The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor.

  18. Multi-hierarchical self-assembly of a collagen mimetic peptide from triple helix to nanofibre and hydrogel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Replicating the multi-hierarchical self-assembly of collagen has long-attracted scientists, from both the perspective of the fundamental science of supramolecular chemistry and that of potential biomedical applications in tissue engineering. Many approaches to drive the self-assembly of synthetic s...

  19. Subvisible Particle Content, Formulation, and Dose of an Erythropoietin Peptide Mimetic Product Are Associated With Severe Adverse Postmarketing Events.

    PubMed

    Kotarek, Joseph; Stuart, Christine; De Paoli, Silvia H; Simak, Jan; Lin, Tsai-Lien; Gao, Yamei; Ovanesov, Mikhail; Liang, Yideng; Scott, Dorothy; Brown, Janice; Bai, Yun; Metcalfe, Dean D; Marszal, Ewa; Ragheb, Jack A

    2016-03-01

    Peginesatide (Omontys(®); Affymax, Inc., Cupertino, CA) was voluntarily withdrawn from the market less than a year after the product launch. Although clinical trials had demonstrated the drug to be safe and efficacious, 49 cases of anaphylaxis, including 7 fatalities, were reported not long after market introduction. Commercialization was initiated with a multiuse vial presentation, which differs in formulation from the single-use vial presentation used in phase 3 studies. Standard physical and chemical testing did not indicate any deviation from product specifications in either formulation. However, an analysis of subvisible particulates using nanoparticle tracking analysis and flow imaging revealed a significantly higher concentration of subvisible particles in the multiuse vial presentation linked to the hypersensitivity cases. Although it is unknown whether the elevated particulate content is causally related to these serious adverse events, this report illustrates the utility of characterizing subvisible particulates not captured by conventional light obscuration. PMID:26886324

  20. Design, synthesis and evaluation of a novel class of glucosamine mimetic peptides containing 1,3-dioxane.

    PubMed

    Zeng, Li; Xu, Guichao; Gao, Pengchao; Zhang, Meng; Li, Hong; Zhang, Jianwei

    2015-03-26

    A number of novel 2-(N-(2-(5,5-dimethyl-1,3-dioxane-2-yl)ethyl)aminoacyl)amino-2-deoxy- d-glucopyranoside were synthesized from a readily available starting material, glucosamine, 2,2-dimethyl-1,3-propanediol and 1,1,3,3-tetramethoxypropane, and evaluated for their anti-inflammatory activity. Our results showed that all of the compounds tested exhibited a significant inhibition of xylene-induced inflammation in mice. PMID:25666911

  1. Active diuretic peptidomimetic insect kinin analogs that contain Beta-turn mimetic motif 4-aminopyroglutamate and lack native peptide bonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The multifunctional arthropod 'insect kinins' share the evolutionarily conserved C-terminal pentapeptide core sequence Phe-X1-X2-Trp-Gly-NH2, where X1 = His, Asn, Ser, or Tyr and X2 = Ser, Pro, or Ala. Insect kinins regulate diuresis in many species of insects, including the cricket. Insect kinins...

  2. Brain natriutetic peptide test

    MedlinePlus

    ... medlineplus.gov/ency/article/007509.htm Brain natriuretic peptide test To use the sharing features on this page, please enable JavaScript. Brain natriuretic peptide (BNP) test is a blood test that measures ...

  3. Vasoactive intestinal peptide test

    MedlinePlus

    ... medlineplus.gov/ency/article/003508.htm Vasoactive intestinal peptide test To use the sharing features on this page, please enable JavaScript. Vasoactive intestinal peptide (VIP) is a test that measures the amount ...

  4. Defining specificity and on-target activity of BH3-mimetics using engineered B-ALL cell lines

    PubMed Central

    Koss, Brian; Ryan, Jeremy; Budhraja, Amit; Szarama, Katherine; Yang, Xue; Bathina, Madhavi; Cardone, Michael H.; Nikolovska-Coleska, Zaneta; Letai, Anthony; Opferman, Joseph T.

    2016-01-01

    One of the hallmarks of cancer is a resistance to the induction of programmed cell death that is mediated by selection of cells with elevated expression of anti-apoptotic members of the BCL-2 family. To counter this resistance, new therapeutic agents known as BH3-mimetic small molecules are in development with the goal of antagonizing the function of anti-apoptotic molecules and promoting the induction of apoptosis. To facilitate the testing and modeling of BH3-mimetic agents, we have developed a powerful system for evaluation and screening of agents both in culture and in immune competent animal models by engineering mouse leukemic cells and re-programming them to be dependent on exogenously expressed human anti-apoptotic BCL-2 family members. Here we demonstrate that this panel of cell lines can determine the specificity of BH3-mimetics to individual anti-apoptotic BCL-2 family members (BCL-2, BCL-XL, BCL-W, BFL-1, and MCL-1), demonstrate whether cell death is due to the induction of apoptosis (BAX and BAK-dependent), and faithfully assess the efficacy of BH3-mimetic small molecules in pre-clinical mouse models. These cells represent a robust and valuable pre-clinical screening tool for validating the efficacy, selectivity, and on-target action of BH3-mimetic agents. PMID:26862853

  5. Defining specificity and on-target activity of BH3-mimetics using engineered B-ALL cell lines.

    PubMed

    Koss, Brian; Ryan, Jeremy; Budhraja, Amit; Szarama, Katherine; Yang, Xue; Bathina, Madhavi; Cardone, Michael H; Nikolovska-Coleska, Zaneta; Letai, Anthony; Opferman, Joseph T

    2016-03-01

    One of the hallmarks of cancer is a resistance to the induction of programmed cell death that is mediated by selection of cells with elevated expression of anti-apoptotic members of the BCL-2 family. To counter this resistance, new therapeutic agents known as BH3-mimetic small molecules are in development with the goal of antagonizing the function of anti-apoptotic molecules and promoting the induction of apoptosis. To facilitate the testing and modeling of BH3-mimetic agents, we have developed a powerful system for evaluation and screening of agents both in culture and in immune competent animal models by engineering mouse leukemic cells and re-programming them to be dependent on exogenously expressed human anti-apoptotic BCL-2 family members. Here we demonstrate that this panel of cell lines can determine the specificity of BH3-mimetics to individual anti-apoptotic BCL-2 family members (BCL-2, BCL-XL, BCL-W, BFL-1, and MCL-1), demonstrate whether cell death is due to the induction of apoptosis (BAX and BAK-dependent), and faithfully assess the efficacy of BH3-mimetic small molecules in pre-clinical mouse models. These cells represent a robust and valuable pre-clinical screening tool for validating the efficacy, selectivity, and on-target action of BH3-mimetic agents. PMID:26862853

  6. [SYNTHETIC PEPTIDE VACCINES].

    PubMed

    Sergeyev, O V; Barinsky, I F

    2016-01-01

    An update on the development and trials of synthetic peptide vaccines is reviewed. The review considers the successful examples of specific protection as a result of immunization with synthetic peptides using various protocols. The importance of conformation for the immunogenicity of the peptide is pointed out. An alternative strategy of the protection of the organism against the infection using synthetic peptides is suggested. PMID:27145593

  7. PH dependent adhesive peptides

    DOEpatents

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  8. Antimicrobial Peptides in 2014

    PubMed Central

    Wang, Guangshun; Mishra, Biswajit; Lau, Kyle; Lushnikova, Tamara; Golla, Radha; Wang, Xiuqing

    2015-01-01

    This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms. PMID:25806720

  9. Antimicrobial peptides in 2014.

    PubMed

    Wang, Guangshun; Mishra, Biswajit; Lau, Kyle; Lushnikova, Tamara; Golla, Radha; Wang, Xiuqing

    2015-01-01

    This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms. PMID:25806720

  10. Mimetic Relation as Matching-to-Sample Observing Response and the Emergence of Speaker Relations in Children with and without Hearing Impairments

    ERIC Educational Resources Information Center

    Elias, Nassim Chamel; Goyos, Celso

    2013-01-01

    This study investigated the effect of matching-to-sample and mimetic-relations teaching on the emergence of signed tact and textual repertoire through a multiple-baseline design, across three groups of three words in children with and without hearing impairments and with no reading repertoire. Following mimetic-relations teaching and the…

  11. In situ chondrogenic differentiation of bone marrow stromal cells in bioactive self-assembled peptide gels.

    PubMed

    Kim, Ji Eun; Kim, Soo Hyun; Jung, Youngmee

    2015-07-01

    Articular cartilage is a specific tissue that lacks nerves and blood vessels and has limited self-repair abilities. Accordingly, it is necessary to develop new technology for the regeneration of cartilage to overcome therapeutic limitations. Recently, there have been several studies investigating the use of peptide hydrogel scaffolds, which are biocompatible and have low immunogenicity, for cartilage tissue engineering. In this study, we used self-assembled peptide hydrogels with repeating peptide sequences and bioactive motifs at the end of repeating sequences, which are collagen mimetic peptides (CMPs). CMPs that have a unique collagen-like triple helical conformation have been shown to associate with collagen molecules and fibers via a strand invasion process. In order to confirm the biological activities of the modified bioactive peptide hydrogels, the role of functional motifs in in situ chondrogenic differentiation of rabbit bone marrow stromal cells (rBMSCs) was examined. To compensate for the weaker mechanical properties of peptide hydrogels, we used poly (L-lactide-co-caprolactone) (PLCL) scaffolds, which were loaded with the self-assembled peptides into which the bioactive motifs had been incorporated. Then, we performed in vitro and in vivo analyses with the rBMSC/PLCL-peptide hydrogel complexes. The results indicated that the secretion of a cartilage-specific extracellular matrix and gene expression concerned with chondrogenic differentiation were increased by CMP motifs. In conclusion, it was confirmed that CMP-modified self-assembled peptide hydrogels could effectively enhance chondrogenic differentiation in situ, and, consequently, they could be a good biomaterial for cartilage tissue engineering. PMID:25540912

  12. Effect of antimicrobial peptides from Australian tree frogs on anionic phospholipid membranes.

    PubMed

    Gehman, John D; Luc, Fiona; Hall, Kristopher; Lee, Tzong-Hsien; Boland, Martin P; Pukala, Tara L; Bowie, John H; Aguilar, Marie-Isabel; Separovic, Frances

    2008-08-19

    Skin secretions of numerous Australian tree frogs contain antimicrobial peptides that form part of the host defense mechanism against bacterial infection. The mode of action of these antibiotics is thought to be lysis of infectious organisms via cell membrane disruption, on the basis of vesicle-encapsulated dye leakage data [Ambroggio et al. (2005) Biophys. J. 89, 1874-1881]. A detailed understanding of the interaction of these peptides with bacterial membranes at a molecular level, however, is critical to their development as novel antibacterial therapeutics. We focus on four of these peptides, aurein 1.2, citropin 1.1, maculatin 1.1, and caerin 1.1, which exist as random coil in aqueous solution but have alpha-helical secondary structure in membrane mimetic environments. In our earlier solid-state NMR studies, only neutral bilayers of the zwitterionic phospholipid dimyristoylphosphatidylcholine (DMPC) were used. Deuterated DMPC ( d 54-DMPC) was used to probe the effect of the peptides on the order of the lipid acyl chains and dynamics of the phospholipid headgroups by deuterium and (31)P NMR, respectively. In this report we demonstrate several important differences when anionic phospholipid is included in model membranes. Peptide-membrane interactions were characterized using surface plasmon resonance (SPR) spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Changes in phospholipid motions and membrane binding information provided additional insight into the action of these antimicrobial peptides. While this set of peptides has significant C- and N-terminal sequence homology, they vary in their mode of membrane interaction. The longer peptides caerin and maculatin exhibited properties that were consistent with transmembrane insertion while citropin and aurein demonstrated membrane disruptive mechanisms. Moreover, aurein was unique with greater perturbation of neutral versus anionic membranes. The results are consistent with a surface

  13. Peptides that anneal to natural collagen in vitro and ex vivo

    PubMed Central

    Chattopadhyay, Sayani; Murphy, Christopher J.; McAnulty, Jonathan F.

    2012-01-01

    Collagen comprises ¼ of the protein in humans and ¾ of the dry weight of human skin. Here, we implement recent discoveries about the structure and stability of the collagen triple helix to design new chemical modalities that anchor to natural collagen. The key components are collagen mimetic peptides (CMPs) that are incapable of self-assembly into homotrimeric triple helices, but are able to anneal spontaneously to natural collagen. We show that such CMPs containing 4-fluoroproline residues, in particular, bind tightly to mammalian collagen in vitro and to a mouse wound ex vivo. These synthetic peptides, coupled to dyes or growth factors, could herald a new era in assessing or treating wounds. PMID:22522497

  14. Encoding Cell-Instructive Cues to PEG-Based Hydrogels via Triple Helical Peptide Assembly

    PubMed Central

    Stahl, Patrick J.

    2013-01-01

    Effective synthetic tissue engineering scaffolds mimic the structure and composition of natural extracellular matrix (ECM) to promote optimal cellular adhesion, proliferation, and differentiation. Among many proteins of the ECM, collagen and fibronectin are known to play a key role in the scaffold’s structural integrity as well as its ability to support cell adhesion. Here, we present photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogels displaying collagen mimetic peptides (CMPs) that can be further conjugated to bioactive molecules via CMP-CMP triple helix association. Pre-formed PEGDA-CMP hydrogels can be encoded with varying concentration of cell-signaling CMP-RGD peptides similar to cell adhesive fibronectin decorating the collagen fibrous network by non-covalent binding. Furthermore, the triple helix mediated encoding allows facile generation of spatial gradients and patterns of cell-instructive cues across the cell scaffold that simulate distribution of insoluble factors in the natural ECM. PMID:23908674

  15. Non-Peptide Macrocyclic Histone Deacetylase Inhibitors Derived from Tricyclic Ketolide Skeleton

    PubMed Central

    Mwakwari, Sandra C.; Guerrant, William; Patil, Vishal; Khan, Shabana I.; Tekwani, Babu L.; Gurard-Levin, Zachary A.; Mrksich, Milan; Oyelere, Adegboyega K.

    2010-01-01

    Inhibition of histone deacetylase (HDAC) function is a validated therapeutic strategy for cancer treatment. Of the several structurally distinct small molecule histone deacetylase inhibitors (HDACi) reported, macrocyclic depsipeptides possess the most complex cap-groups and have demonstrated excellent HDAC inhibition potency and isoform selectivity. Unfortunately, the development of macrocyclic depsipeptides has been hampered in part due to development problems characteristic of large peptides and the complex reaction schemes required for their synthesis. Herein we report that tricyclic ketolide TE-802 is an excellent mimetic for the peptide backbone of macrocyclic HDACi. Compounds derived from this template are particularly selective against HDAC 1 and 2 with nanomolar inhibitory activity. Interrogation of the association between a subset of these compounds and key HDAC isoforms, using AutoDock, enables a molecular description of the interaction between the HDAC enzyme's outer rim and the inhibitors’ macrocyclic cap group that are responsible for compound affinity and presumably isoform selectivity. PMID:20669972

  16. Better Living through Chemistry: Caloric Restriction (CR) and CR Mimetics Alter Genome Function to Promote Increased Health and Lifespan.

    PubMed

    Gillespie, Zoe E; Pickering, Joshua; Eskiw, Christopher H

    2016-01-01

    Caloric restriction (CR), defined as decreased nutrient intake without causing malnutrition, has been documented to increase both health and lifespan across numerous organisms, including humans. Many drugs and other compounds naturally occurring in our diet (nutraceuticals) have been postulated to act as mimetics of caloric restriction, leading to a wave of research investigating the efficacy of these compounds in preventing age-related diseases and promoting healthier, longer lifespans. Although well studied at the biochemical level, there are still many unanswered questions about how CR and CR mimetics impact genome function and structure. Here we discuss how genome function and structure are influenced by CR and potential CR mimetics, including changes in gene expression profiles and epigenetic modifications and their potential to identify the genetic fountain of youth. PMID:27588026

  17. A framework for developing a mimetic tensor artificial viscosity for Lagrangian hydrocodes on arbitrary polygonal and polyhedral meshes (u)

    SciTech Connect

    Lipnikov, Konstantin; Shashkov, Mikhail

    2011-01-11

    We construct a new mimetic tensor artificial viscosity on general polygonal and polyhedral meshes. The tensor artificial viscosity is based on a mimetic discretization of coordinate invariant operators, divergence of a tensor and gradient of a vector. The focus of this paper is on the symmetric form, div ({mu},{var_epsilon}(u)), of the tensor artificial viscosity where {var_epsilon}(u) is the symmetrized gradient of u and {mu}, is a tensor. The mimetic discretizations of this operator is derived for the case of a full tensor coefficient {mu}, that may reflect a shock direction. We demonstrate performance of the new viscosity for the Noh implosion, Sedov explosion and Saltzman piston problems in both Cartesian and axisymmetric coordinate systems.

  18. Better Living through Chemistry: Caloric Restriction (CR) and CR Mimetics Alter Genome Function to Promote Increased Health and Lifespan

    PubMed Central

    Gillespie, Zoe E.; Pickering, Joshua; Eskiw, Christopher H.

    2016-01-01

    Caloric restriction (CR), defined as decreased nutrient intake without causing malnutrition, has been documented to increase both health and lifespan across numerous organisms, including humans. Many drugs and other compounds naturally occurring in our diet (nutraceuticals) have been postulated to act as mimetics of caloric restriction, leading to a wave of research investigating the efficacy of these compounds in preventing age-related diseases and promoting healthier, longer lifespans. Although well studied at the biochemical level, there are still many unanswered questions about how CR and CR mimetics impact genome function and structure. Here we discuss how genome function and structure are influenced by CR and potential CR mimetics, including changes in gene expression profiles and epigenetic modifications and their potential to identify the genetic fountain of youth. PMID:27588026

  19. Dynamics and Conformational Studies of TOAC Spin Labeled Analogues of Ctx(Ile21)-Ha Peptide from Hypsiboas albopunctatus

    PubMed Central

    Vicente, Eduardo F.; Basso, Luis Guilherme M.; Cespedes, Graziely F.; Lorenzón, Esteban N.; Castro, Mariana S.; Mendes-Giannini, Maria José S.; Costa-Filho, Antonio José; Cilli, Eduardo M.

    2013-01-01

    Antimicrobial peptides (AMPs) isolated from several organisms have been receiving much attention due to some specific features that allow them to interact with, bind to, and disrupt cell membranes. The aim of this paper was to study the interactions between a membrane mimetic and the cationic AMP Ctx(Ile21)-Ha as well as analogues containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) incorporated at residue positions n = 0, 2, and 13. Circular dichroism studies showed that the peptides, except for [TOAC13]Ctx(Ile21)-Ha, are unstructured in aqueous solution but acquire different amounts of α-helical secondary structure in the presence of trifluorethanol and lysophosphocholine micelles. Fluorescence experiments indicated that all peptides were able to interact with LPC micelles. In addition, Ctx(Ile21)-Ha and [TOAC13]Ctx(Ile21)-Ha peptides presented similar water accessibility for the Trp residue located near the N-terminal sequence. Electron spin resonance experiments showed two spectral components for [TOAC0]Ctx(Ile21)-Ha, which are most likely due to two membrane-bound peptide conformations. In contrast, TOAC2 and TOAC13 derivatives presented a single spectral component corresponding to a strong immobilization of the probe. Thus, our findings allowed the description of the peptide topology in the membrane mimetic, where the N-terminal region is in dynamic equilibrium between an ordered, membrane-bound conformation and a disordered, mobile conformation; position 2 is most likely situated in the lipid polar head group region, and residue 13 is fully inserted into the hydrophobic core of the membrane. PMID:23585852

  20. Foldameric α/β-peptide analogs of the β-sheet-forming antiangiogenic anginex: structure and bioactivity.

    PubMed

    Hegedüs, Zsófia; Wéber, Edit; Kriston-Pál, Éva; Makra, Ildikó; Czibula, Ágnes; Monostori, Éva; Martinek, Tamás A

    2013-11-01

    The principles of β-sheet folding and design for α-peptidic sequences are well established, while those for sheet mimetics containing homologated amino acid building blocks are still under investigation. To reveal the structure-function relations of β-amino-acid-containing foldamers, we followed a top-down approach to study a series of α/β-peptidic analogs of anginex, a β-sheet-forming antiangiogenic peptide. Eight anginex analogs were developed by systematic α → β(3) substitutions and analyzed by using NMR and CD spectroscopy. The foldamers retained the β-sheet tendency, though with a decreased folding propensity. β-Sheet formation could be induced by a micellar environment, similarly to that of the parent peptide. The destructuring effect was higher when the α → β(3) exchange was located in the β-sheet core. Analysis of the β-sheet stability versus substitution pattern and the local conformational bias of the bulky β(3)V and β(3)I residues revealed that a mismatch between the H-bonding preferences of the α- and β-residues played a minor role in the structure-breaking effect. Temperature-dependent CD and NMR measurements showed that the hydrophobic stabilization was scaled-down for the α/β-peptides. Analysis of the biological activity of the foldamer peptides showed that four anginex derivatives dose-dependently inhibited the proliferation of a mouse endothelial cell line. The α → β(3) substitution strategy applied in this work can be a useful approach to the construction of bioactive β-sheet mimetics with a reduced aggregation tendency and improved pharmacokinetic properties. PMID:24088182

  1. An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

    PubMed Central

    Marano, Grazia; Gronewold, Claas; Frank, Martin; Merling, Anette; Kliem, Christian; Sauer, Sandra; Wiessler, Manfred; Frei, Eva

    2012-01-01

    Summary Oligosaccharides aberrantly expressed on tumor cells influence processes such as cell adhesion and modulation of the cell’s microenvironment resulting in an increased malignancy. Schmidt’s imidate strategy offers an effective method to synthesize libraries of various oligosaccharide mimetics. With the aim to perturb interactions of tumor cells with extracellular matrix proteins and host cells, molecules with 3,4-bis(hydroxymethyl)furan as core structure were synthesized and screened in biological assays for their abilities to interfere in cell adhesion and other steps of the metastatic cascade, such as tumor-induced angiogenesis. The most active compound, (4-{[(β-D-galactopyranosyl)oxy]methyl}furan-3-yl)methyl hydrogen sulfate (GSF), inhibited the activation of matrix-metalloproteinase-2 (MMP-2) as well as migration of the human melanoma cells of the lines WM-115 and WM-266-4 in a two-dimensional migration assay. GSF inhibited completely the adhesion of WM-115 cells to the extracellular matrix (ECM) proteins, fibrinogen and fibronectin. In an in vitro angiogenesis assay with human endothelial cells, GSF very effectively inhibited endothelial tubule formation and sprouting of blood vessels, as well as the adhesion of endothelial cells to ECM proteins. GSF was not cytotoxic at biologically active concentrations; neither were 3,4-bis{[(β-D-galactopyranosyl)oxy]methyl}furan (BGF) nor methyl β-D-galactopyranoside nor 3,4-bis(hydroxymethyl)furan, which were used as controls, eliciting comparable biological activity. In silico modeling experiments, in which binding of GSF to the extracellular domain of the integrin αvβ3 was determined, revealed specific docking of GSF to the same binding site as the natural peptidic ligands of this integrin. The sulfate in the molecule coordinated with one manganese ion in the binding site. These studies show that this chemically easily accessible molecule GSF, synthesized in three steps from 3,4-bis

  2. Differential role of RIP1 in Smac mimetic-mediated chemosensitization of neuroblastoma cells

    PubMed Central

    Czaplinski, Sebastian; Abhari, Behnaz Ahangarian; Torkov, Alica; SeggewiΔ, Dominik; Hugle, Manuela; Fulda, Simone

    2015-01-01

    We explored the potential of Smac mimetics, which antagonize Inhibitor of Apoptosis (IAP) proteins, for chemosensitization of neuroblastoma (NB). Here, we report that Smac mimetics, e.g. BV6, prime NB cells for chemotherapeutics including the topoisomerase II inhibitor doxorubicin (DOX) and vinca alkaloids such as Vincristine (VCR), Vinblastine (VBL) and Vinorelbine (VNR). Additionally, BV6 acts in concert with DOX or VCR to suppress long-term clonogenic growth. While BV6 causes rapid downregulation of cellular IAP (cIAP)1 protein and nuclear factor-kappaB (NF-κB) activation, DOX/BV6- or VCR/BV6-induced apoptosis occurs independently of NF-κB or TNFα signaling, since overexpression of dominant-negative IκBα superrepressor or the Tumor Necrosis Factor (TNF)α-blocking antibody Enbrel fail to block cell death. Mechanistic studies reveal that Receptor-interacting protein (RIP)1 is required for DOX/BV6-, but not for VCR/BV6-induced apoptosis, since transient or stable knockdown of RIP1 or the pharmacological RIP1 inhibitor necrostatin-1 significantly reduce apoptosis. By comparison, VCR/BV6-mediated apoptosis critically depends on the mitochondrial pathway. VCR/BV6 cotreatment causes phosphorylation of BCL-2 during mitotic arrest, enhanced activation of BAX and BAK and loss of mitochondrial membrane potential (MMP). Additionally, overexpression of BCL-2 profoundly suppresses VCR/BV6-induced apoptosis. Thus, BV6 sensitizes NB cells to chemotherapy-induced apoptosis via distinct initial signaling mechanisms depending on the chemotherapeutic drug. These findings provide novel mechanistic insights into Smac mimetic-mediated chemosensitization of NB. PMID:26575016

  3. Differential role of RIP1 in Smac mimetic-mediated chemosensitization of neuroblastoma cells.

    PubMed

    Czaplinski, Sebastian; Abhari, Behnaz Ahangarian; Torkov, Alica; Seggewiß, Dominik; Hugle, Manuela; Fulda, Simone

    2015-12-01

    We explored the potential of Smac mimetics, which antagonize Inhibitor of Apoptosis (IAP) proteins, for chemosensitization of neuroblastoma (NB). Here, we report that Smac mimetics, e.g. BV6, prime NB cells for chemotherapeutics including the topoisomerase II inhibitor doxorubicin (DOX) and vinca alkaloids such as Vincristine (VCR), Vinblastine (VBL) and Vinorelbine (VNR). Additionally, BV6 acts in concert with DOX or VCR to suppress long-term clonogenic growth. While BV6 causes rapid downregulation of cellular IAP (cIAP)1 protein and nuclear factor-kappaB (NF-κB) activation, DOX/BV6- or VCR/BV6-induced apoptosis occurs independently of NF-κB or TNFα signaling, since overexpression of dominant-negative IκBα superrepressor or the Tumor Necrosis Factor (TNF)α-blocking antibody Enbrel fail to block cell death. Mechanistic studies reveal that Receptor-interacting protein (RIP)1 is required for DOX/BV6-, but not for VCR/BV6-induced apoptosis, since transient or stable knockdown of RIP1 or the pharmacological RIP1 inhibitor necrostatin-1 significantly reduce apoptosis. By comparison, VCR/BV6-mediated apoptosis critically depends on the mitochondrial pathway. VCR/BV6 cotreatment causes phosphorylation of BCL-2 during mitotic arrest, enhanced activation of BAX and BAK and loss of mitochondrial membrane potential (MMP). Additionally, overexpression of BCL-2 profoundly suppresses VCR/BV6-induced apoptosis. Thus, BV6 sensitizes NB cells to chemotherapy-induced apoptosis via distinct initial signaling mechanisms depending on the chemotherapeutic drug. These findings provide novel mechanistic insights into Smac mimetic-mediated chemosensitization of NB. PMID:26575016

  4. Epitope mapping of B-cell determinants on the 15-kilodalton lipoprotein of Treponema pallidum (Tpp15) with synthetic peptides.

    PubMed Central

    Baughn, R E; Demecs, M; Taber, L H; Musher, D M

    1996-01-01

    The antigenicity of the 15-kDa lipoprotein of Treponema pallidum (Tpp15 or TpN15) was comprehensively evaluated in epitope-scanning studies with overlapping deca- and octapeptides and polygonal rabbit and human infant immunoglobulins (Igs) and antisera. This approach enabled us to identify potentially important regions and to determine the optimal dilutions of Igs or antisera for use in further studies. IgM and IgG from both species were capable of recognizing multiple, continuous epitopes. A total of 13 peptides, principally clustered in the central regions of the protein, were recognized by all syphilitic sera and Ig fractions. On the basis of window analyses, frequency profiles, and alanine substitution studies, five heptapeptides were selected for mimetic studies. Two of these five immunodominant, continuous epitopes initially appeared to be species specific; however, antisera elicited against mimetics of all five epitopes were polyspecific, recognizing similar motifs on several other treponemal proteins, including those of avirulent organisms. The only mimetic which yielded positive reactions with infant IgM and syphilitic sera in the absence of cross-reactions with rabbit antisera to avirulent treponemes was the variant of the VMYASSG motif. These findings are relevant to the development of simple, inexpensive assays for the serodiagnosis of active syphilis. PMID:8698467

  5. Accelerating cosmologies and the phase structure of F (R ) gravity with Lagrange multiplier constraints: A mimetic approach

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-01-01

    We study mimetic F (R ) gravity with a potential and Lagrange multiplier constraint. In the context of these theories, we introduce a reconstruction technique which enables us to realize arbitrary cosmologies, given the Hubble rate and an arbitrarily chosen F (R ) gravity. We exemplify our method by realizing cosmologies that are in concordance with current observations (Planck data) and also well-known bouncing cosmologies. The attribute of our method is that the F (R ) gravity can be arbitrarily chosen, so we can have the appealing features of the mimetic approach combined with the known features of some F (R ) gravities, which unify early-time with late-time acceleration. Moreover, we study the existence and the stability of de Sitter points in the context of mimetic F (R ) gravity. In the case of unstable de Sitter points, it is demonstrated that graceful exit from inflation occurs. We also study the Einstein-frame counterpart theory of the Jordan-frame mimetic F (R ) gravity, and we discuss the general properties of the theory and exemplify our analysis by studying a quite interesting (from a phenomenological point of view) model with two scalar fields. We also calculate the observational indices of the two-scalar-field model, by using the two-scalar-field formalism. Furthermore, we extensively study the dynamical system that corresponds to the mimetic F (R ) gravity, by finding the fixed points and studying their stability. Finally, we modify our reconstruction method to function in the inverse way and thus yield which F (R ) gravity can realize a specific cosmological evolution, given the mimetic potential and the Lagrange multiplier.

  6. Functional Mimetics of the HIV-1 CCR5 Co-Receptor Displayed on the Surface of Magnetic Liposomes

    PubMed Central

    Kuzmina, Alona; Vaknin, Karin; Gdalevsky, Garik; Vyazmensky, Maria; Marks, Robert S.; Taube, Ran

    2015-01-01

    Chemokine G protein coupled receptors, principally CCR5 or CXCR4, function as co-receptors for HIV-1 entry into CD4+ T cells. Initial binding of the viral envelope glycoprotein (Env) gp120 subunit to the host CD4 receptor induces a cascade of structural conformational changes that lead to the formation of a high-affinity co-receptor-binding site on gp120. Interaction between gp120 and the co-receptor leads to the exposure of epitopes on the viral gp41 that mediates fusion between viral and cell membranes. Soluble CD4 (sCD4) mimetics can act as an activation-based inhibitor of HIV-1 entry in vitro, as it induces similar structural changes in gp120, leading to increased virus infectivity in the short term but to virus Env inactivation in the long term. Despite promising clinical implications, sCD4 displays low efficiency in vivo, and in multiple HIV strains, it does not inhibit viral infection. This has been attributed to the slow kinetics of the sCD4-induced HIV Env inactivation and to the failure to obtain sufficient sCD4 mimetic levels in the serum. Here we present uniquely structured CCR5 co-receptor mimetics. We hypothesized that such mimetics will enhance sCD4-induced HIV Env inactivation and inhibition of HIV entry. Co-receptor mimetics were derived from CCR5 gp120-binding epitopes and functionalized with a palmitoyl group, which mediated their display on the surface of lipid-coated magnetic beads. CCR5-peptidoliposome mimetics bound to soluble gp120 and inhibited HIV-1 infectivity in a sCD4-dependent manner. We concluded that CCR5-peptidoliposomes increase the efficiency of sCD4 to inhibit HIV infection by acting as bait for sCD4-primed virus, catalyzing the premature discharge of its fusion potential. PMID:26629902

  7. The Mimetic Finite Element Method and the Virtual Element Method for elliptic problems with arbitrary regularity.

    SciTech Connect

    Manzini, Gianmarco

    2012-07-13

    We develop and analyze a new family of virtual element methods on unstructured polygonal meshes for the diffusion problem in primal form, that use arbitrarily regular discrete spaces V{sub h} {contained_in} C{sup {alpha}} {element_of} N. The degrees of freedom are (a) solution and derivative values of various degree at suitable nodes and (b) solution moments inside polygons. The convergence of the method is proven theoretically and an optimal error estimate is derived. The connection with the Mimetic Finite Difference method is also discussed. Numerical experiments confirm the convergence rate that is expected from the theory.

  8. Chroman-4-one and chromone based somatostatin β-turn mimetics.

    PubMed

    Fridén-Saxin, Maria; Seifert, Tina; Malo, Marcus; da Silva Andersson, Krystle; Pemberton, Nils; Dyrager, Christine; Friberg, Annika; Dahlén, Kristian; Wallén, Erik A A; Grøtli, Morten; Luthman, Kristina

    2016-05-23

    A scaffold approach has been used to develop somatostatin β-turn mimetics based on chroman-4-one and chromone ring systems. Such derivatives could adopt conformations resembling type II or type II' β-turns. Side chain equivalents of the crucial Trp8 and Lys9 in somatostatin were introduced in the 2- and 8-positions of the scaffolds using efficient reactions. Interestingly, this proof-of-concept study shows that 4 and 9 have Ki-values in the low μM range when evaluated for their affinity for the sst2 and sst4 receptors. PMID:26974375

  9. Mimetic discretization of the Abelian Chern-Simons theory and link invariants

    SciTech Connect

    Di Bartolo, Cayetano; Grau, Javier; Leal, Lorenzo

    2013-12-15

    A mimetic discretization of the Abelian Chern-Simons theory is presented. The study relies on the formulation of a theory of differential forms in the lattice, including a consistent definition of the Hodge duality operation. Explicit expressions for the Gauss Linking Number in the lattice, which correspond to their continuum counterparts are given. A discussion of the discretization of metric structures in the space of transverse vector densities is presented. The study of these metrics could serve to obtain explicit formulae for knot an link invariants in the lattice.

  10. From Complex Natural Products to Simple Synthetic Mimetics by Computational De Novo Design.

    PubMed

    Friedrich, Lukas; Rodrigues, Tiago; Neuhaus, Claudia S; Schneider, Petra; Schneider, Gisbert

    2016-06-01

    We present the computational de novo design of synthetically accessible chemical entities that mimic the complex sesquiterpene natural product (-)-Englerin A. We synthesized lead-like probes from commercially available building blocks and profiled them for activity against a computationally predicted panel of macromolecular targets. Both the design template (-)-Englerin A and its low-molecular weight mimetics presented nanomolar binding affinities and antagonized the transient receptor potential calcium channel TRPM8 in a cell-based assay, without showing target promiscuity or frequent-hitter properties. This proof-of-concept study outlines an expeditious solution to obtaining natural-product-inspired chemical matter with desirable properties. PMID:27111835

  11. Novel thrombin inhibitors incorporating non-basic partially saturated heterobicyclic P1-arginine mimetics.

    PubMed

    Peterlin-Masic, Lucija; Mlinsek, Gregor; Solmajer, Tomaz; Trampus-Bakija, Alenka; Stegnar, Mojca; Kikelj, Danijel

    2003-03-10

    The design, synthesis and biological activity of non-covalent thrombin inhibitors incorporating 4,5,6,7-tetrahydroindazole, 2-methyl-4,5,6,7-tetrahydroindazole, 4,5,6,7-tetrahydroisoindole, 5,6,7,8-tetrahydroquinazoline and 5,6,7,8-tetrahydroquinazolin-2-amine as novel, partially saturated, heterobicyclic P(1)-arginine side-chain mimetics is described. The binding mode of the most potent candidate in the series co-crystallized with human alpha-thrombin, which exhibited an in vitro K(i) of 140nM and more that 478-fold selectivity against trypsin, is discussed. PMID:12617892

  12. STAT1, STAT3 and p38MAPK are involved in the apoptotic effect induced by a chimeric cyclic interferon-{alpha}2b peptide

    SciTech Connect

    Blank, Viviana C.; Pena, Clara; Roguin, Leonor P.

    2010-02-15

    In the search of mimetic peptides of the interferon-{alpha}2b molecule (IFN-{alpha}2b), we have previously designed and synthesized a chimeric cyclic peptide of the IFN-{alpha}2b that inhibits WISH cell proliferation by inducing an apoptotic response. Here, we first studied the ability of this peptide to activate intracellular signaling pathways and then evaluated the participation of some signals in the induction of apoptosis. Stimulation of WISH cells with the cyclic peptide showed tyrosine phosphorylation of Jak1 and Tyk2 kinases, tyrosine and serine phosphorylation of STAT1 and STAT3 transcription factors and activation of p38 MAPK pathway, although phosphorylation levels or kinetics were in some conditions different to those obtained under IFN-{alpha}2b stimulus. JNK and p44/42 pathways were not activated by the peptide in WISH cells. We also showed that STAT1 and STAT3 downregulation by RNA interference decreased the antiproliferative activity and the amount of apoptotic cells induced by the peptide. Pharmacological inhibition of p38 MAPK also reduced the peptide growth inhibitory activity and the apoptotic effect. Thus, we demonstrated that the cyclic peptide regulates WISH cell proliferation through the activation of Jak/STAT signaling pathway. In addition, our results indicate that p38 MAPK may also be involved in cell growth regulation. This study suggests that STAT1, STAT3 and p38 MAPK would be mediating the antitumor and apoptotic response triggered by the cyclic peptide in WISH cells.

  13. [Plant signaling peptides. Cysteine-rich peptides].

    PubMed

    Ostrowski, Maciej; Kowalczyk, Stanisław

    2015-01-01

    Recent bioinformatic and genetic analyses of several model plant genomes have revealed the existence of a highly abundant group of signaling peptides that are defined as cysteine-rich peptides (CRPs). CRPs are usually in size between 50 and 90 amino acid residues, they are positively charged, and they contain 4-16 cysteine residues that are important for the correct conformational folding. Despite the structural differences among CRP classes, members from each class have striking similarities in their molecular properties and function. The present review presents the recent progress in research on signaling peptides from several families including: EPF/EPFL, SP11/SCR, PrsS, RALF, LURE, and some other peptides belonging to CRP group. There is convincing evidence indicating multiple roles for these CRPs as signaling molecules during the plant life cycle, ranging from stomata development and patterning, self-incompatibility, pollen tube growth and guidance, reproductive processes, and nodule formation. PMID:26281357

  14. Cell Penetrating Peptides and Cationic Antibacterial Peptides

    PubMed Central

    Rodriguez Plaza, Jonathan G.; Morales-Nava, Rosmarbel; Diener, Christian; Schreiber, Gabriele; Gonzalez, Zyanya D.; Lara Ortiz, Maria Teresa; Ortega Blake, Ivan; Pantoja, Omar; Volkmer, Rudolf; Klipp, Edda; Herrmann, Andreas; Del Rio, Gabriel

    2014-01-01

    Cell penetrating peptides (CPP) and cationic antibacterial peptides (CAP) have similar physicochemical properties and yet it is not understood how such similar peptides display different activities. To address this question, we used Iztli peptide 1 (IP-1) because it has both CPP and CAP activities. Combining experimental and computational modeling of the internalization of IP-1, we show it is not internalized by receptor-mediated endocytosis, yet it permeates into many different cell types, including fungi and human cells. We also show that IP-1 makes pores in the presence of high electrical potential at the membrane, such as those found in bacteria and mitochondria. These results provide the basis to understand the functional redundancy of CPPs and CAPs. PMID:24706763

  15. Investigation of bn-44 Peptide Fragments Using High Resolution Mass Spectrometry and Isotope Labeling

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Yu, Jiayi; Wang, Huixin; Wei, Zhonglin; Guo, Xinhua; Xiao, Zhaohui; Zeng, Zhoufang; Kong, Wei

    2014-12-01

    An N-terminal deuterohemin-containing hexapeptide (DhHP-6) was designed as a short peptide cytochrome c (Cyt c) mimetic to study the effect of N-terminal charge on peptide fragmentation pathways. This peptide gave different dissociation patterns than normal tryptic peptides. Upon collision-induced dissociation (CID) with an ion trap mass spectrometer, the singly charged peptide ion containing no added proton generated abundant and characteristic bn-44 ions instead of bn-28 (an) ions. Studies by high resolution mass spectrometry (HRMS) and isotope labeling indicate that elimination of 44 Da fragments from b ions occurs via two different pathways: (1) loss of CH3CHO (44.0262) from a Thr side chain; (2) loss of CO2 (43.9898) from the oxazolone structure in the C-terminus. A series of analogues were designed and analyzed. The experimental results combined with Density Functional Theory (DFT) calculations on the proton affinity of the deuteroporphyrin demonstrate that the production of these novel bn-44 ions is related to the N-terminal charge via a charge-remote rather than radical-directed fragmentation pathway.

  16. Development of a Single-Chain Peptide Agonist of the Relaxin-3 Receptor Using Hydrocarbon Stapling.

    PubMed

    Hojo, Keiko; Hossain, Mohammed Akhter; Tailhades, Julien; Shabanpoor, Fazel; Wong, Lilian L L; Ong-Pålsson, Emma E K; Kastman, Hanna E; Ma, Sherie; Gundlach, Andrew L; Rosengren, K Johan; Wade, John D; Bathgate, Ross A D

    2016-08-25

    Structure-activity studies of the insulin superfamily member, relaxin-3, have shown that its G protein-coupled receptor (RXFP3) binding site is contained within its central B-chain α-helix and this helical structure is essential for receptor activation. We sought to develop a single B-chain mimetic that retained agonist activity. This was achieved by use of solid phase peptide synthesis together with on-resin ruthenium-catalyzed ring closure metathesis of a pair of judiciously placed i,i+4 α-methyl, α-alkenyl amino acids. The resulting hydrocarbon stapled peptide was shown by solution NMR spectroscopy to mimic the native helical conformation of relaxin-3 and to possess potent RXFP3 receptor binding and activation. Alternative stapling procedures were unsuccessful, highlighting the critical need to carefully consider both the peptide sequence and stapling methodology for optimal outcomes. Our result is the first successful minimization of an insulin-like peptide to a single-chain α-helical peptide agonist which will facilitate study of the function of relaxin-3. PMID:27464307

  17. Peptide-modified PELCL electrospun membranes for regulation of vascular endothelial cells.

    PubMed

    Zhou, Fang; Jia, Xiaoling; Yang, Yang; Yang, Qingmao; Gao, Chao; Zhao, Yunhui; Fan, Yubo; Yuan, Xiaoyan

    2016-11-01

    The efficiency of biomaterials used in small vascular repair depends greatly on their ability to interact with vascular endothelial cells (VECs). Rapid endothelialization of the vascular grafts is a promising way to prevent thrombosis and intimal hyperplasia. In this work, modification of electrospun membranes of poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) (PELCL) by three different peptides for regulation of VECs were studied in order to obtain ideal bioactive biomaterials as small diameter vascular grafts. QK (a mimetic peptide to vascular endothelial growth factor), Arg-Glu-Asp-Val (REDV, a specific adhesive peptide to VECs) and Val-Ala-Pro-Gly (VAPG, a specific adhesive peptide to vascular smooth muscle cells) were investigated. Surface properties of the modified membranes and the response of VECs were verified. It was found that protein adsorption and platelet adhesion were effectively suppressed with the introduction of QK, REDV or VAPG peptides on the PELCL electrospun membranes. Both QK- and REDV-modified electrospun membranes could accelerate the proliferation of VECs in the first 9days, and the QK-modified electrospun membrane promoted cell proliferation more significantly than the REDV-modified one. The REDV-modified PELCL membrane was the most favorable for VECs adhesion than QK- and VAPG-modified membranes. It was suggested that QK- or REDV-modified PELCL electrospun membranes may have great potential applications in cardiovascular biomaterials for rapid endothelialization in situ. PMID:27524062

  18. Antibacterial and leishmanicidal activities of temporin-SHd, a 17-residue long membrane-damaging peptide.

    PubMed

    Abbassi, Feten; Raja, Zahid; Oury, Bruno; Gazanion, Elodie; Piesse, Christophe; Sereno, Denis; Nicolas, Pierre; Foulon, Thierry; Ladram, Ali

    2013-02-01

    Temporins are a family of short antimicrobial peptides (8-17 residues) that mostly show potent activity against Gram-positive bacteria. Herein, we demonstrate that temporin-SHd, a 17-residue peptide with a net charge of +2 (FLPAALAGIGGILGKLF(amide)), expressed a broad spectrum of antimicrobial activity. This peptide displayed potent antibacterial activities against Gram-negative and Gram-positive bacteria, including multi-drug resistant Staphylococcus aureus strains, as well as antiparasitic activity against promastigote and the intracellular stage (amastigote) of Leishmania infantum, at concentration not toxic for the macrophages. Temporin-SHd that is structured in a non-amphipathic α-helix in anionic membrane-mimetic environments, strongly and selectively perturbs anionic bilayer membranes by interacting with the polar head groups and acyl region of the phospholipids, with formation of regions of two coexisting phases: one phase rich in peptide and the other lipid-rich. The disruption of lipid packing within the bilayer may lead to the formation of transient pores and membrane permeation/disruption once a threshold peptide accumulation is reached. To our knowledge, Temporin-SHd represents the first known 17-residue long temporin expressing such broad spectrum of antimicrobial activity including members of the trypanosomatidae family. Additionally, since only a few shorter members (13 residues) of the temporin family are known to display antileishmanial activity (temporins-TA, -TB and -SHa), SHd is an interesting tool to analyze the antiparasitic mechanism of action of temporins. PMID:23116712

  19. Plant peptide hormone signalling.

    PubMed

    Motomitsu, Ayane; Sawa, Shinichiro; Ishida, Takashi

    2015-01-01

    The ligand-receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone-receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions. PMID:26374891

  20. Peptides and polypeptides as scaffolds for optoelectronics and biomaterials applications

    NASA Astrophysics Data System (ADS)

    Charati, Manoj B.

    Peptides and polypeptides are emerging as a new class of biomaterials due to their unique structural, physiochemical, mechanical, and biological properties. The development of peptide and protein-based biomaterials is driven by the convergence of convenient techniques for peptide/protein engineering and its importance in applications as smart biomaterials. The thesis is divided in two parts; the first part highlights the importance of incorporation of non-natural amino acids into peptides and proteins. In particular, incorporation on p-bromophenylalanine in short alpha-helical peptide templates to control the association of chromophores is discussed. In the second part, design of a multi-component, biocompatible polypeptide with superior elasticity is discussed. Part 1. Novel peptide templates to control association of chromophores. Tailor made peptide and protein materials have many versatile applications, as both conformation and functional group position can be controlled. Such control may have intriguing applications in the development of hybrid materials for electroactive applications. A critical need in fabricating devices from organic semiconducting materials is to achieve control over the conformation and distance between two conjugated chains. Controlling chromophore spacing and orientation with required precision over nanometer length scale poses a greater challenge. Here we propose a peptide based template to control the alignment of the methylstilbene and Oxa-PPV chromophores with desired orientations and spacing. The hybrid peptides were characterized via CD, exciton coupled CD, 1H NMR and photoluminescence experiments. It is observed that slight change in the orientation of molecules has pronounced effect on the photo-physical behavior of the molecules. Characterization of the hybrid peptides via circular dichroism (CD) confirmed the helical character of the designed peptides and indicated that inclusion of non-natural amino acids has significant

  1. The polysialic acid mimetics 5-nonyloxytryptamine and vinorelbine facilitate nervous system repair.

    PubMed

    Saini, Vedangana; Lutz, David; Kataria, Hardeep; Kaur, Gurcharan; Schachner, Melitta; Loers, Gabriele

    2016-01-01

    Polysialic acid (PSA) is a large negatively charged glycan mainly attached to the neural cell adhesion molecule (NCAM). Several studies have shown that it is important for correct formation of brain circuitries during development and for synaptic plasticity, learning and memory in the adult. PSA also plays a major role in nervous system regeneration following injury. As a next step for clinical translation of PSA based therapeutics, we have previously identified the small organic compounds 5-nonyloxytryptamine and vinorelbine as PSA mimetics. Activity of 5-nonyloxytryptamine and vinorelbine had been confirmed in assays with neural cells from the central and peripheral nervous system in vitro and shown to be independent of their function as serotonin receptor 5-HT1B/1D agonist or cytostatic drug, respectively. As we show here in an in vivo paradigm for spinal cord injury in mice, 5-nonyloxytryptamine and vinorelbine enhance regain of motor functions, axonal regrowth, motor neuron survival and remyelination. These data indicate that 5-nonyloxytryptamine and vinorelbine may be re-tasked from their current usage as a 5-HT1B/1D agonist or cytostatic drug to act as mimetics for PSA to stimulate regeneration after injury in the mammalian nervous system. PMID:27324620

  2. RNAi delivery by exosome-mimetic nanovesicles - Implications for targeting c-Myc in cancer.

    PubMed

    Lunavat, Taral R; Jang, Su Chul; Nilsson, Lisa; Park, Hyun Taek; Repiska, Gabriela; Lässer, Cecilia; Nilsson, Jonas A; Gho, Yong Song; Lötvall, Jan

    2016-09-01

    To develop RNA-based therapeutics, it is crucial to create delivery vectors that transport the RNA molecule into the cell cytoplasm. Naturally released exosomes vesicles (also called "Extracellular Vesicles") have been proposed as possible RNAi carriers, but their yield is relatively small in any cell culture system. We have previously generated exosome-mimetic nanovesicles (NV) by serial extrusions of cells through nano-sized filters, which results in 100-times higher yield of extracellular vesicles. We here test 1) whether NV can be loaded with siRNA exogenously and endogenously, 2) whether the siRNA-loaded NV are taken up by recipient cells, and 3) whether the siRNA can induce functional knock-down responses in recipient cells. A siRNA against GFP was first loaded into NV by electroporation, or a c-Myc shRNA was expressed inside of the cells. The NV were efficiently loaded with siRNA with both techniques, were taken up by recipient cells, which resulted in attenuation of target gene expression. In conclusion, our study suggests that exosome-mimetic nanovesicles can be a platform for RNAi delivery to cell cytoplasm. PMID:27344366

  3. Prussian blue nanoparticles as peroxidase mimetics for sensitive colorimetric detection of hydrogen peroxide and glucose.

    PubMed

    Zhang, Weimin; Ma, Diao; Du, Jianxiu

    2014-03-01

    Prussian blue nanoparticles (PB NPs) exhibits an intrinsic peroxidase-like catalytic activity towards the hydrogen peroxide (H2O2)-mediated oxidation of classical peroxidase substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt to produce a colored product. The catalysis follows Michaelis-Menen kinetics and shows strong affinity for H2O2. Using PB NPs as a peroxidase mimetics, a colorimetric method was developed for the detection of 0.05-50.0 μM H2O2, with a detection limit of 0.031 μM. When the catalytic reaction of PB NPs was coupled with the reaction of glucose oxidation catalyzed by glucose oxidase, a sensitive and selective colorimetric method for the detection of glucose was realized. The limit of detection for glucose was determined to be as low as 0.03 μM and the linear range was from 0.1 μM to 50.0 μM. The method was successfully applied to the determination of glucose in human serum. Compared with other nanomaterials-based peroxidase mimetics, PB NPs provides 10-100 times higher sensitivity toward the detection of H2O2 and glucose. The detection platform developed showed great potential applications in varieties of physiological importance substances when merged with appropriate H2O2-producing oxidases. PMID:24468383

  4. The BCL-2 protein family, BH3-mimetics and cancer therapy

    PubMed Central

    Delbridge, A R D; Strasser, A

    2015-01-01

    Escape from apoptosis is a key attribute of tumour cells and facilitates chemo-resistance. The ‘BCL-2-regulated' or ‘intrinsic' apoptotic pathway integrates stress and survival signalling to govern whether a cancer cell will live or die. Indeed, many pro-apoptotic members of the BCL-2 family have demonstrated tumour-suppression activity in mouse models of cancer and are lost or repressed in certain human cancers. Conversely, overexpression of pro-survival BCL-2 family members promotes tumorigenesis in humans and in mouse models. Many of the drugs currently used in the clinic mediate their therapeutic effects (at least in part) through the activation of the BCL-2-regulated apoptotic pathway. However, initiators of this apoptotic pathway, such as p53, are mutated, lost or silenced in many human cancers rendering them refractory to treatment. To counter such resistance mechanisms, a novel class of therapeutics, ‘BH3-mimetics', has been developed. These drugs directly activate apoptosis by binding and inhibiting select antiapoptotic BCL-2 family members and thereby bypass the requirement for upstream initiators, such as p53. In this review, we discuss the role of the BCL-2 protein family in the development and treatment of cancer, with an emphasis on mechanistic studies using well-established mouse models of cancer, before describing the development and already recognised potential of the BH3-mimetic compounds. PMID:25952548

  5. Prophylactic treatment with the BH3 mimetic ABT-737 impedes Myc-driven lymphomagenesis in mice.

    PubMed

    Kelly, P N; Grabow, S; Delbridge, A R D; Adams, J M; Strasser, A

    2013-01-01

    As many oncogenic changes, such as Myc overexpression, promote apoptosis, the survival of emerging neoplastic clones may often initially depend upon endogenous levels of particular pro-survival members of the Bcl-2 protein family. Pertinently, we recently showed that in lymphoma-prone Eμ-myc transgenic mice, which overexpress Myc in all B-lymphoid cells, endogenous Bcl-x(L) is critical for the survival, as well as the expansion of preneoplastic B-lymphoid cells and the development of malignant disease. This discovery raised the possibility that pharmacological blockade of Bcl-x(L) might impede Myc-driven lymphoma development. Indeed, we report here that treatment of preleukaemic Eμ-myc transgenic mice with the Bcl-2 homology (BH)3 mimetic drug ABT-737, which inhibits Bcl-x(L), as well as Bcl-2 and Bcl-w, augmented apoptosis of preneoplastic B-lymphoid cells, reduced their numbers and greatly prolonged lymphoma-free survival. These findings reveal that BH3 mimetic drugs may provide a prophylactic strategy to prevent the development of certain tumours, particularly those driven by deregulated Myc expression. Moreover, such treatment may help in the management of patients with hereditary cancer syndromes and perhaps also in the prevention of tumour relapses. PMID:22814621

  6. Stick-slip friction of gecko-mimetic flaps on smooth and rough surfaces.

    PubMed

    Das, Saurabh; Cadirov, Nicholas; Chary, Sathya; Kaufman, Yair; Hogan, Jack; Turner, Kimberly L; Israelachvili, Jacob N

    2015-03-01

    The discovery and understanding of gecko 'frictional-adhesion' adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick-slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick-slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick-slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. PMID:25589569

  7. Acute Sensitivity of Ph-like Acute Lymphoblastic Leukemia to the SMAC-Mimetic Birinapant.

    PubMed

    Richmond, Jennifer; Robbins, Alissa; Evans, Kathryn; Beck, Dominik; Kurmasheva, Raushan T; Billups, Catherine A; Carol, Hernan; Heatley, Sue; Sutton, Rosemary; Marshall, Glenn M; White, Deborah; Pimanda, John; Houghton, Peter J; Smith, Malcolm A; Lock, Richard B

    2016-08-01

    Ph-like acute lymphoblastic leukemia (ALL) is a genetically defined high-risk ALL subtype with a generally poor prognosis. In this study, we evaluated the efficacy of birinapant, a small-molecule mimetic of the apoptotic regulator SMAC, against a diverse set of ALL subtypes. Birinapant exhibited potent and selective cytotoxicity against B-cell precursor ALL (BCP-ALL) cells that were cultured ex vivo or in vivo as patient-derived tumor xenografts (PDX). Cytotoxicity was consistently most acute in Ph-like BCP-ALL. Unbiased gene expression analysis of BCP-ALL PDX specimens identified a 68-gene signature associated with birinapant sensitivity, including an enrichment for genes involved in inflammatory response, hematopoiesis, and cell death pathways. All Ph-like PDXs analyzed clustered within this 68-gene classifier. Mechanistically, birinapant sensitivity was associated with expression of TNF receptor TNFR1 and was abrogated by interfering with the TNFα/TNFR1 interaction. In combination therapy, birinapant enhanced the in vivo efficacy of an induction-type regimen of vincristine, dexamethasone, and L-asparaginase against Ph-like ALL xenografts, offering a preclinical rationale to further evaluate this SMAC mimetic for BCP-ALL treatment. Cancer Res; 76(15); 4579-91. ©2016 AACR. PMID:27302164

  8. Synthesis of cellulose nanocrystals carrying tyrosine sulfate mimetic ligands and inhibition of alphavirus infection.

    PubMed

    Zoppe, Justin O; Ruottinen, Ville; Ruotsalainen, Janne; Rönkkö, Seppo; Johansson, Leena-Sisko; Hinkkanen, Ari; Järvinen, Kristiina; Seppälä, Jukka

    2014-04-14

    We present two facile approaches for introducing multivalent displays of tyrosine sulfate mimetic ligands on the surface of cellulose nanocrystals (CNCs) for application as viral inhibitors. We tested the efficacy of cellulose nanocrystals, prepared either from cotton fibers or Whatman filter paper, to inhibit alphavirus infectivity in Vero (B) cells. Cellulose nanocrystals were produced by sulfuric acid hydrolysis leading to nanocrystal surfaces decorated with anionic sulfate groups. When the fluorescent marker expressing Semliki Forest virus vector, VA7-EGFP, was incubated with CNCs, strong inhibition of virus infectivity was achieved, up to 100 and 88% for cotton and Whatman CNCs, respectively. When surface sulfate groups of CNCs were exchanged for tyrosine sulfate mimetic groups (i.e. phenyl sulfonates), improved viral inhibition was attained. Our observations suggest that the conjugation of target-specific functionalities to CNC surfaces provides a means to control their antiviral activity. Multivalent CNCs did not cause observable in vitro cytotoxicity to Vero (B) cells or human corneal epithelial (HCE-T) cells, even within the 100% virus-inhibitory concentrations. Based on the similar chemistry of known polyanionic inhibitors, our results suggest the potential application of CNCs as inhibitors of other viruses, such as human immunodeficiency virus (HIV) and herpes simplex viruses. PMID:24628489

  9. A mimetic finite difference method for the Stokes problem with elected edge bubbles

    SciTech Connect

    Lipnikov, K; Berirao, L

    2009-01-01

    A new mimetic finite difference method for the Stokes problem is proposed and analyzed. The unstable P{sub 1}-P{sub 0} discretization is stabilized by adding a small number of bubble functions to selected mesh edges. A simple strategy for selecting such edges is proposed and verified with numerical experiments. The discretizations schemes for Stokes and Navier-Stokes equations must satisfy the celebrated inf-sup (or the LBB) stability condition. The stability condition implies a balance between discrete spaces for velocity and pressure. In finite elements, this balance is frequently achieved by adding bubble functions to the velocity space. The goal of this article is to show that the stabilizing edge bubble functions can be added only to a small set of mesh edges. This results in a smaller algebraic system and potentially in a faster calculations. We employ the mimetic finite difference (MFD) discretization technique that works for general polyhedral meshes and can accomodate non-uniform distribution of stabilizing bubbles.

  10. Covalent binding and anchoring of cytochrome c to mitochondrial mimetic membranes promoted by cholesterol carboxyaldehyde.

    PubMed

    Genaro-Mattos, Thiago C; Appolinário, Patricia P; Mugnol, Katia C U; Bloch, Carlos; Nantes, Iseli L; Di Mascio, Paolo; Miyamoto, Sayuri

    2013-10-21

    Mitochondrial cholesterol has been reported to be increased under specific pathological conditions associated with enhanced oxidative stress parameters. In this scenario, cholesterol oxidation would be increased, leading to the production of reactive aldehydes, including cholesterol carboxyaldehyde (ChAld). By using SDS micelles as a mitochondrial mimetic model, we have demonstrated that ChAld covalently modifies cytochrome c (cytc), a protein known to participate in electron transport and apoptosis signaling. This mimetic model induces changes in cytc structure in the same way as mitochondrial membranes do. Tryptic digestion of the cytc-ChAld adduct followed by MALDI-TOF/TOF analyses revealed that modifications occur at Lys residues (K22) localized at cytc site L, a site involved in protein-protein and protein-membrane interactions. Interestingly, ChAld ligation prevented cytc detachment from liposomes even under high ionic strength conditions. Overall, it can be concluded that ChAld ligation to Lys residues at site L creates a hydrophobic tail at cytc, which promotes cytc anchoring to the membrane. Although not investigated in detail in this study, cytc adduction to cholesterol derived aldehydes could have implications in cytc release from mitochondria under apoptotic stimuli. PMID:24059586

  11. Evidence for a Müllerian mimetic radiation in Asian pitvipers.

    PubMed

    Sanders, K L; Malhotra, A; Thorpe, R S

    2006-05-01

    Müllerian mimicry, in which toxic species gain mutual protection from shared warning signals, is poorly understood in vertebrates, reflecting a paucity of examples. Indirect evidence for mimicry is found if monophyletic species or clades show parallel geographic variation in warning patterns. Here, we evaluate a hypothesis of Müllerian mimicry for the pitvipers in Southeast Asia using a phylogeny derived from DNA sequences from four combined mitochondrial regions. Mantel matrix correlation tests show that conspicuous red colour pattern elements are significantly associated with sympatric and parapatric populations in four genera. To our knowledge, this represents the first evidence of a Müllerian mimetic radiation in vipers. The putative mimetic patterns are rarely found in females. This appears paradoxical in light of the Müllerian prediction of monomorphism, but may be explained by divergent selection pressures on the sexes, which have different behaviours. We suggest that biased predation on active males causes selection for protective warning coloration, whereas crypsis is favoured in relatively sedentary females. PMID:16600892

  12. Accuracy analysis of mimetic finite volume operators on geodesic grids and a consistent alternative

    NASA Astrophysics Data System (ADS)

    Peixoto, Pedro S.

    2016-04-01

    Many newly developed climate, weather and ocean global models are based on quasi-uniform spherical polygonal grids, aiming for high resolution and better scalability. Thuburn et al. (2009) and Ringler et al. (2010) developed a C staggered finite volume/difference method for arbitrary polygonal spherical grids suitable for these next generation dynamical cores. This method has many desirable mimetic properties and became popular, being adopted in some recent models, in spite of being known to possess low order of accuracy. In this work, we show that, for the nonlinear shallow water equations on non-uniform grids, the method has potentially 3 main sources of inconsistencies (local truncation errors not converging to zero as the grid is refined): (i) the divergence term of the continuity equation, (ii) the perpendicular velocity and (iii) the kinetic energy terms of the vector invariant form of the momentum equations. Although some of these inconsistencies have not impacted the convergence on some standard shallow water test cases up until now, they may constitute a potential problem for high resolution 3D models. Based on our analysis, we propose modifications for the method that will make it first order accurate in the maximum norm. It preserves many of the mimetic properties, albeit having non-steady geostrophic modes on the f-sphere. Experimental results show that the resulting model is a more accurate alternative to the existing formulations and should provide means of having a consistent, computationally cheap and scalable atmospheric or ocean model on C staggered Voronoi grids.

  13. The polysialic acid mimetics 5-nonyloxytryptamine and vinorelbine facilitate nervous system repair

    PubMed Central

    Saini, Vedangana; Lutz, David; Kataria, Hardeep; Kaur, Gurcharan; Schachner, Melitta; Loers, Gabriele

    2016-01-01

    Polysialic acid (PSA) is a large negatively charged glycan mainly attached to the neural cell adhesion molecule (NCAM). Several studies have shown that it is important for correct formation of brain circuitries during development and for synaptic plasticity, learning and memory in the adult. PSA also plays a major role in nervous system regeneration following injury. As a next step for clinical translation of PSA based therapeutics, we have previously identified the small organic compounds 5-nonyloxytryptamine and vinorelbine as PSA mimetics. Activity of 5-nonyloxytryptamine and vinorelbine had been confirmed in assays with neural cells from the central and peripheral nervous system in vitro and shown to be independent of their function as serotonin receptor 5-HT1B/1D agonist or cytostatic drug, respectively. As we show here in an in vivo paradigm for spinal cord injury in mice, 5-nonyloxytryptamine and vinorelbine enhance regain of motor functions, axonal regrowth, motor neuron survival and remyelination. These data indicate that 5-nonyloxytryptamine and vinorelbine may be re-tasked from their current usage as a 5-HT1B/1D agonist or cytostatic drug to act as mimetics for PSA to stimulate regeneration after injury in the mammalian nervous system. PMID:27324620

  14. Modeling anisotropic flow and heat transport by using mimetic finite differences

    NASA Astrophysics Data System (ADS)

    Chen, Tao; Clauser, Christoph; Marquart, Gabriele; Willbrand, Karen; Büsing, Henrik

    2016-08-01

    Modeling anisotropic flow in porous or fractured rock often assumes that the permeability tensor is diagonal, which means that its principle directions are always aligned with the coordinate axes. However, the permeability of a heterogeneous anisotropic medium usually is a full tensor. For overcoming this shortcoming, we use the mimetic finite difference method (mFD) for discretizing the flow equation in a hydrothermal reservoir simulation code, SHEMAT-Suite, which couples this equation with the heat transport equation. We verify SHEMAT-Suite-mFD against analytical solutions of pumping tests, using both diagonal and full permeability tensors. We compare results from three benchmarks for testing the capability of SHEMAT-Suite-mFD to handle anisotropic flow in porous and fractured media. The benchmarks include coupled flow and heat transport problems, three-dimensional problems and flow through a fractured porous medium with full equivalent permeability tensor. It shows firstly that the mimetic finite difference method can model anisotropic flow both in porous and in fractured media accurately and its results are better than those obtained by the multi-point flux approximation method in highly anisotropic models, secondly that the asymmetric permeability tensor can be included and leads to improved results compared the symmetric permeability tensor in the equivalent fracture models, and thirdly that the method can be easily implemented in existing finite volume or finite difference codes, which has been demonstrated successfully for SHEMAT-Suite.

  15. Stick–slip friction of gecko-mimetic flaps on smooth and rough surfaces

    PubMed Central

    Das, Saurabh; Cadirov, Nicholas; Chary, Sathya; Kaufman, Yair; Hogan, Jack; Turner, Kimberly L.; Israelachvili, Jacob N.

    2015-01-01

    The discovery and understanding of gecko ‘frictional-adhesion’ adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick–slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick–slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick–slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. PMID:25589569

  16. Antihypertensive peptides from curd

    PubMed Central

    Dabarera, Melani Chathurika; Athiththan, Lohini V.; Perera, Rasika P.

    2015-01-01

    Introduction: Curd (Dadhi) peptides reduce hypertension by inhibiting angiotensin converting enzyme (ACE) and serum cholesterol. Peptides vary with bacterial species and milk type used during fermentation. Aim: To isolate and assay the antihypertensive peptides, before and after digestion, in two commercially available curd brands in Sri Lanka. Materials and Methods: Whey (Dadhi Mastu) separated by high-speed centrifugation was isolated using reverse-phase-high- performance liquid chromatography (HPLC). Eluted fractions were analyzed for ACE inhibitory activity using modified Cushman and Cheung method. Curd samples were subjected to enzymatic digestion with pepsin, trypsin, and carboxypeptidase-A at their optimum pH and temperature. Peptides isolated using reverse-phase-HPLC was assayed for ACE inhibitory activity. Results: Whey peptides of both brands gave similar patterns (seven major and five minor peaks) in HPLC elution profile. Smaller peptides concentration was higher in brand 1 and penta-octapeptides in brand 2. Pentapeptide had the highest ACE inhibitory activity (brand 2–90% and brand 1–73%). After digestion, di and tri peptides with similar inhibitory patterns were obtained in both which were higher than before digestion. Thirteen fractions were obtained, where nine fractions showed more than 70% inhibition in both brands with 96% ACE inhibition for a di-peptide. Conclusion: Curd has ACE inhibitory peptides and activity increases after digestion. PMID:27011726

  17. Antimicrobial Peptides in Reptiles

    PubMed Central

    van Hoek, Monique L.

    2014-01-01

    Reptiles are among the oldest known amniotes and are highly diverse in their morphology and ecological niches. These animals have an evolutionarily ancient innate-immune system that is of great interest to scientists trying to identify new and useful antimicrobial peptides. Significant work in the last decade in the fields of biochemistry, proteomics and genomics has begun to reveal the complexity of reptilian antimicrobial peptides. Here, the current knowledge about antimicrobial peptides in reptiles is reviewed, with specific examples in each of the four orders: Testudines (turtles and tortosises), Sphenodontia (tuataras), Squamata (snakes and lizards), and Crocodilia (crocodilans). Examples are presented of the major classes of antimicrobial peptides expressed by reptiles including defensins, cathelicidins, liver-expressed peptides (hepcidin and LEAP-2), lysozyme, crotamine, and others. Some of these peptides have been identified and tested for their antibacterial or antiviral activity; others are only predicted as possible genes from genomic sequencing. Bioinformatic analysis of the reptile genomes is presented, revealing many predicted candidate antimicrobial peptides genes across this diverse class. The study of how these ancient creatures use antimicrobial peptides within their innate immune systems may reveal new understandings of our mammalian innate immune system and may also provide new and powerful antimicrobial peptides as scaffolds for potential therapeutic development. PMID:24918867

  18. Polycyclic peptide therapeutics.

    PubMed

    Baeriswyl, Vanessa; Heinis, Christian

    2013-03-01

    Owing to their excellent binding properties, high stability, and low off-target toxicity, polycyclic peptides are an attractive molecule format for the development of therapeutics. Currently, only a handful of polycyclic peptides are used in the clinic; examples include the antibiotic vancomycin, the anticancer drugs actinomycin D and romidepsin, and the analgesic agent ziconotide. All clinically used polycyclic peptide drugs are derived from natural sources, such as soil bacteria in the case of vancomycin, actinomycin D and romidepsin, or the venom of a fish-hunting coil snail in the case of ziconotide. Unfortunately, nature provides peptide macrocyclic ligands for only a small fraction of therapeutic targets. For the generation of ligands of targets of choice, researchers have inserted artificial binding sites into natural polycyclic peptide scaffolds, such as cystine knot proteins, using rational design or directed evolution approaches. More recently, large combinatorial libraries of genetically encoded bicyclic peptides have been generated de novo and screened by phage display. In this Minireview, the properties of existing polycyclic peptide drugs are discussed and related to their interesting molecular architectures. Furthermore, technologies that allow the development of unnatural polycyclic peptide ligands are discussed. Recent application of these technologies has generated promising results, suggesting that polycyclic peptide therapeutics could potentially be developed for a broad range of diseases. PMID:23355488

  19. Peptide folding simulations.

    PubMed

    Gnanakaran, S; Nymeyer, Hugh; Portman, John; Sanbonmatsu, Kevin Y; García, Angel E

    2003-04-01

    Developments in the design of small peptides that mimic proteins in complexity, recent advances in nanosecond time-resolved spectroscopy methods to study peptides and the development of modern, highly parallel simulation algorithms have come together to give us a detailed picture of peptide folding dynamics. Two newly implemented simulation techniques, parallel replica dynamics and replica exchange molecular dynamics, can now describe directly from simulations the kinetics and thermodynamics of peptide formation, respectively. Given these developments, the simulation community now has the tools to verify and validate simulation protocols and models (forcefields). PMID:12727509

  20. L-Eye to Me: The Combined Role of Need for Cognition and Facial Trustworthiness in Mimetic Desires

    ERIC Educational Resources Information Center

    Treinen, Evelyne; Corneille, Olivier; Luypaert, Gaylord

    2012-01-01

    Recent studies showed that stimuli are evaluated more favourably when they are perceived to capture others' attention, an effect coined "mimetic desire". The aim of the present research was to examine the combined role of Need for Cognition and target's facial trustworthiness in this effect. Participants saw movie excerpts of trustworthy and…

  1. Theoretical studies on the interactions of XIAP-BIR3 domain with bicyclic and tricyclic core monovalent Smac mimetics.

    PubMed

    Ling, Baoping; Dong, Lihua; Zhang, Rui; Wang, Zhiguo; Liu, Yongjun; Liu, Chengbu

    2010-11-01

    X-linked IAP can bind caspase-9 and inhibit its activity. Mitochondrial protein Smac/DIABLO can also interact with XIAP and relieve the inhibition on caspase-9 to induce apoptosis. A series of artificial Smac mimetics have been used to mimic the Smac N-terminal tetrapeptide AVPI to bind to XIAP-BIR3, but these structural diverse mimetics exhibited distinct binding affinities. To get an insight into the binding nature and optimize the structures, molecular docking and dynamics simulations were used to study the binding of XIAP-BIR3 with three groups of Smac mimetics. The docking results reveal that these Smac mimetics anchored on the surface groove of XIAP-BIR3 and superimposed well with AVPI. The modifications on the seven-membered ring of bicyclic core segment do not strengthen the binding affinity, while a benzyl introduced to the five-membered ring is favorable to the binding. Molecular dynamics simulations on three typical systems show that these complexes are very stable. Hydrogen bonds between the bicyclic core segment and Thr308 play critical roles in maintaining the stability of complex. The binding free energies calculated by MM_PBSA method are consistent with the experimental results. PMID:20980180

  2. Intrinsic and chemo-sensitizing activity of SMAC-mimetics on high-risk childhood acute lymphoblastic leukemia

    PubMed Central

    Schirmer, M; Trentin, L; Queudeville, M; Seyfried, F; Demir, S; Tausch, E; Stilgenbauer, S; Eckhoff, S M; Meyer, L H; Debatin, K-M

    2016-01-01

    SMAC-mimetics represent a targeted therapy approach to overcome apoptosis resistance in many tumors. Here, we investigated the efficacy of the SMAC-mimetic BV6 in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). In ALL cell lines, intrinsic apoptosis sensitivity was associated with rapid cIAP degradation, NF-κB activation, TNF-α secretion and induction of an autocrine TNF-α-dependent cell death loop. This pattern of responsiveness was also observed upon ex vivo analysis of 40 primograft BCP-ALL samples. Treatment with BV6 induced cell death in the majority of ALL primografts including leukemias with high-risk and poor-prognosis features. Inhibition of cell death by the TNF receptor fusion protein etanercept demonstrated that BV6 activity is dependent on TNF-α. In a preclinical NOD/SCID/huALL model of high-risk ALL, marked anti-leukemia effectivity and significantly prolonged survival were observed upon BV6 treatment. Interestingly, also in vivo, intrinsic SMAC-mimetic activity was mediated by TNF-α. Importantly, BV6 increased the effectivity of conventional induction therapy including vincristine, dexamethasone and asparaginase leading to prolonged remission induction. These data suggest SMAC-mimetics as an important addendum to efficient therapy of pediatric BCP-ALL. PMID:26775704

  3. Antibody elicited against the gp41 N-heptad repeat (NHR) coiled-coil can neutralize HIV-1 with modest potency but non-neutralizing antibodies also bind to NHR mimetics

    SciTech Connect

    Nelson, Josh D.; Kinkead, Heather; Brunel, Florence M.; Leaman, Dan; Jensen, Richard; Louis, John M.; Maruyama, Toshiaki; Bewley, Carole A.; Bowdish, Katherine; Clore, G. Marius; Dawson, Philip E.; Frederickson, Shana; Mage, Rose G.; Richman, Douglas D.; Burton, Dennis R.; Zwick, Michael B.

    2008-07-20

    Following CD4 receptor binding to the HIV-1 envelope spike (Env), the conserved N-heptad repeat (NHR) region of gp41 forms a coiled-coil that is a precursor to the fusion reaction. Although it has been a target of drug and vaccine design, there are few monoclonal antibody (mAb) tools with which to probe the antigenicity and immunogenicity specifically of the NHR coiled-coil. Here, we have rescued HIV-1-neutralizing anti-NHR mAbs from immune phage display libraries that were prepared (i) from b9 rabbits immunized with a previously described mimetic of the NHR coiled-coil, N35{sub CCG}-N13, and (ii) from an HIV-1 infected individual. We describe a rabbit single-chain Fv fragment (scFv), 8K8, and a human Fab, DN9, which specifically recognize NHR coiled-coils that are unoccupied by peptide corresponding to the C-heptad repeat or CHR region of gp41 (e.g. C34). The epitopes of 8K8 and DN9 were found to partially overlap with that of a previously described anti-NHR mAb, IgG D5; however, 8K8 and DN9 were much more specific than D5 for unoccupied NHR trimers. The mAbs, including a whole IgG 8K8 molecule, neutralized primary HIV-1 of clades B and C in a pseudotyped virus assay with comparable, albeit relatively modest potency. Finally, a human Fab T3 and a rabbit serum (both non-neutralizing) were able to block binding of D5 and 8K8 to a gp41 NHR mimetic, respectively, but not the neutralizing activity of these mAbs. We conclude from these results that NHR coiled-coil analogs of HIV-1 gp41 elicit many Abs during natural infection and through immunization, but that due to limited accessibility to the corresponding region on fusogenic gp41 few can neutralize. Caution is therefore required in targeting the NHR for vaccine design. Nevertheless, the mAb panel may be useful as tools for elucidating access restrictions to the NHR of gp41 and in designing potential improvements to mimetics of receptor-activated Env.

  4. Iron oxide superparamagnetic nanoparticles conjugated with a conformationally blocked α-Tn antigen mimetic for macrophage activation

    NASA Astrophysics Data System (ADS)

    Manuelli, Massimo; Fallarini, Silvia; Lombardi, Grazia; Sangregorio, Claudio; Nativi, Cristina; Richichi, Barbara

    2014-06-01

    Among new therapies to fight tumors, immunotherapy is still one of the most promising and intriguing. Thanks to the ongoing structural elucidation of several tumor antigens and the development of innovative antigen carriers, immunotherapy is in constant evolution and it is largely used either alone or in synergy with chemotherapy/radiotherapy. With the aim to develop fully synthetic immunostimulants we have recently developed a mimetic of the α-Tn mucin antigen, a relevant tumor antigen. The 4C1 blocked mimetic 1, unique example of an α-Tn mimetic antigen, was functionalized with an ω-phosphonate linker and used to decorate iron oxide superparamagnetic nanoparticles (MNPs), employed as multivalent carriers. MNPs, largely exploited for supporting and carrying biomolecules, like antibodies, drugs or antigens, consent to combine in the same nanometric system the main features of an inorganic magnetic core with a bioactive organic coating. The superparamagnetic glyconanoparticles obtained, named GMNPs, are indeed biocompatible and immunoactive, and they preserve suitable characteristics for use as heat mediators in the magnetic fluid hyperthermia (MFH) treatment of tumors. All together these properties make GMNPs attracting devices for innovative tumor treatment.Among new therapies to fight tumors, immunotherapy is still one of the most promising and intriguing. Thanks to the ongoing structural elucidation of several tumor antigens and the development of innovative antigen carriers, immunotherapy is in constant evolution and it is largely used either alone or in synergy with chemotherapy/radiotherapy. With the aim to develop fully synthetic immunostimulants we have recently developed a mimetic of the α-Tn mucin antigen, a relevant tumor antigen. The 4C1 blocked mimetic 1, unique example of an α-Tn mimetic antigen, was functionalized with an ω-phosphonate linker and used to decorate iron oxide superparamagnetic nanoparticles (MNPs), employed as multivalent

  5. Structure and Mechanism of Beta-Hairpin Antimicrobial Peptides in Lipid Bilayers from Solid-State NMR Spectroscopy

    PubMed Central

    Tang, Ming; Hong, Mei

    2010-01-01

    The membrane-bound structure, lipid interaction, and dynamics of the arginine-rich β-hairpin antimicrobial peptide PG-1 as studied by solid-state NMR is highlighted here. A variety of solid-state NMR techniques, including paramagnetic relaxation enhancement, 1H and 19F spin diffusion, dipolar recoupling distance experiments, and 2D anisotropic-isotropic correlation experiments, are used to elucidate the structural basis for the membrane disruptive activity of this representative β-hairpin antimicrobial peptide. We found that PG-1 structure is membrane dependent: in bacteria-mimetic anionic lipid membranes the peptide forms oligomeric transmembrane β-barrels, whereas in cholesterol-rich membranes mimicking eukaryotic cells the peptide forms β-sheet aggregates on the surface of the bilayer. PG-1 causes toroidal pore defects in the anionic membrane, suggesting that the cationic arginine residues drag the lipid phosphate groups along as the peptide inserts. Mutation of PG-1 to reduce the number of cationic residues or to change the arginine guanidinium structure significantly changes the degree of insertion and orientation of the peptide in the lipid membrane, resulting in much weaker antimicrobial activities. PMID:19396367

  6. Insulin C-peptide test

    MedlinePlus

    C-peptide ... the test depends on the reason for the C-peptide measurement. Ask your health care provider if ... C-peptide is measured to tell the difference between insulin produced by the body and insulin injected ...

  7. Bacteriocin Inducer Peptides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel peptides produced by bacteriocin-producing bacteria stimulate the production of bacteriocins in vitro. The producer bacteria are cultured in the presence of a novel inducer bacteria and a peptide having a carboxy terminal sequence of VKGLT in order to achieve an increase in bacteriocin produc...

  8. Antimicrobial Peptides from Fish

    PubMed Central

    Masso-Silva, Jorge A.; Diamond, Gill

    2014-01-01

    Antimicrobial peptides (AMPs) are found widely distributed through Nature, and participate in the innate host defense of each species. Fish are a great source of these peptides, as they express all of the major classes of AMPs, including defensins, cathelicidins, hepcidins, histone-derived peptides, and a fish-specific class of the cecropin family, called piscidins. As with other species, the fish peptides exhibit broad-spectrum antimicrobial activity, killing both fish and human pathogens. They are also immunomodulatory, and their genes are highly responsive to microbes and innate immuno-stimulatory molecules. Recent research has demonstrated that some of the unique properties of fish peptides, including their ability to act even in very high salt concentrations, make them good potential targets for development as therapeutic antimicrobials. Further, the stimulation of their gene expression by exogenous factors could be useful in preventing pathogenic microbes in aquaculture. PMID:24594555

  9. Targeting p38 or MK2 Enhances the Anti-Leukemic Activity of Smac-Mimetics.

    PubMed

    Lalaoui, Najoua; Hänggi, Kay; Brumatti, Gabriela; Chau, Diep; Nguyen, Nhu-Y N; Vasilikos, Lazaros; Spilgies, Lisanne M; Heckmann, Denise A; Ma, Chunyan; Ghisi, Margherita; Salmon, Jessica M; Matthews, Geoffrey M; de Valle, Elisha; Moujalled, Donia M; Menon, Manoj B; Spall, Sukhdeep Kaur; Glaser, Stefan P; Richmond, Jennifer; Lock, Richard B; Condon, Stephen M; Gugasyan, Raffi; Gaestel, Matthias; Guthridge, Mark; Johnstone, Ricky W; Munoz, Lenka; Wei, Andrew; Ekert, Paul G; Vaux, David L; Wong, W Wei-Lynn; Silke, John

    2016-02-01

    Birinapant is a smac-mimetic (SM) in clinical trials for treating cancer. SM antagonize inhibitor of apoptosis (IAP) proteins and simultaneously induce tumor necrosis factor (TNF) secretion to render cancers sensitive to TNF-induced killing. To enhance SM efficacy, we screened kinase inhibitors for their ability to increase TNF production of SM-treated cells. We showed that p38 inhibitors increased TNF induced by SM. Unexpectedly, even though p38 is required for Toll-like receptors to induce TNF, loss of p38 or its downstream kinase MK2 increased induction of TNF by SM. Hence, we show that the p38/MK2 axis can inhibit or promote TNF production, depending on the stimulus. Importantly, clinical p38 inhibitors overcame resistance of primary acute myeloid leukemia to birinapant. PMID:26859455

  10. Elastin-Mimetic Protein Polymers Capable of Physical and Chemical Crosslinking

    PubMed Central

    Sallach, Rory E.; Cui, Wanxing; Wen, Jing; Martinez, Adam; Conticello, Vincent P.; Chaikof, Elliot L.

    2008-01-01

    We report the synthesis of a new class of recombinant elastin-mimetic triblock copolymer capable of both physical and chemical crosslinking. These investigations were motivated by a desire to capture features unique to both physical and chemical crosslinking schemes so as to exert optimal control over a wide range of potential properties afforded by protein-based mutiblock materials. We postulated that by chemically locking a multiblock protein assembly in place, functional responses that are linked to specific domain structures and morphologies may be preserved over a broader range of loading conditions that would otherwise disrupt microphase structure solely stabilized by physical crosslinking. Specifically, elastic modulus was enhanced and creep strain reduced through the addition of chemical crosslinking sites. Additionally, we have demonstrated excellent in vivo biocompatibility of glutaraldehyde treated multiblock systems. PMID:18954902

  11. Virus-mimetic nanovesicles as a versatile antigen-delivery system

    PubMed Central

    Zhang, Pengfei; Chen, Yixin; Zeng, Yun; Shen, Chenguang; Li, Rui; Guo, Zhide; Li, Shaowei; Zheng, Qingbing; Chu, Chengchao; Wang, Zhantong; Zheng, Zizheng; Tian, Rui; Ge, Shengxiang; Zhang, Xianzhong; Xia, Ning-Shao; Liu, Gang; Chen, Xiaoyuan

    2015-01-01

    It is a critically important challenge to rapidly design effective vaccines to reduce the morbidity and mortality of unexpected pandemics. Inspired from the way that most enveloped viruses hijack a host cell membrane and subsequently release by a budding process that requires cell membrane scission, we genetically engineered viral antigen to harbor into cell membrane, then form uniform spherical virus-mimetic nanovesicles (VMVs) that resemble natural virus in size, shape, and specific immunogenicity with the help of surfactants. Incubation of major cell membrane vesicles with surfactants generates a large amount of nano-sized uniform VMVs displaying the native conformational epitopes. With the diverse display of epitopes and viral envelope glycoproteins that can be functionally anchored onto VMVs, we demonstrate VMVs to be straightforward, robust and tunable nanobiotechnology platforms for fabricating antigen delivery systems against a wide range of enveloped viruses. PMID:26504197

  12. Mucoadhesion and mucosa-mimetic materials--A mini-review.

    PubMed

    Cook, Michael T; Khutoryanskiy, Vitaliy V

    2015-11-30

    Mucoadhesion describes an attractive interaction between dosage form and mucosal membrane. The evaluation of mucoadhesive excipients often requires the use of ex vivo mucosal tissues taken from laboratory animals. These can be difficult to source, highly heterogeneous, and require the use of animal products. Thus, from both a user-convenience and ethical point-of-view, it is desirable to produce a synthetic alternative to these tissues-a mucosa-mimetic material. In this mini-review, the use of alternative materials to test the performance of mucoadhesives is reviewed and discussed. There is a surprising prevalence of the use of mucosa-mimics in the literature, which hitherto has not been compiled and compared. PMID:26440734

  13. A comparative investigation of mussel-mimetic sealants for fetal membrane repair.

    PubMed

    Perrini, Michela; Barrett, Devin; Ochsenbein-Koelble, Nicole; Zimmermann, Roland; Messersmith, Phillip; Ehrbar, Martin

    2016-05-01

    Towards the prevention of iatrogenic preterm premature rupture of the fetal membrane, two mussel-mimetic tissue adhesives (cT and cPEG) have been compared and qualified as possible sealants for membrane repair. Monotonic and cyclic inflation tests of repaired fetal membranes were carried out in order to investigate the performance of the glues under quasi-static, fast, and repeated loading. Finite element simulations of repaired and inflated synthetic membranes allowed to compare cT and cPEG under large deformations. Both adhesives seal the membrane well, resisting pressures higher than the intra-uterine baseline. Only under repeated mechanical load, as well as under fast and acute deformation of the membrane, the sealing performance has deteriorated. Even though cT loses adhesion to the deformed membrane, it is able to withstand high deformations and pressures without rupturing, while cPEG breaks. PMID:26255212

  14. Sialic Acid Mimetics to Target the Sialic Acid-Siglec Axis.

    PubMed

    Büll, Christian; Heise, Torben; Adema, Gosse J; Boltje, Thomas J

    2016-06-01

    Sialic acid sugars are vital regulators of the immune system through binding to immunosuppressive sialic acid-binding immunoglobulin-like lectin (Siglec) receptors on immune cells. Aberrant sialic acid-Siglec interactions are associated with an increasing number of pathologies including infection, autoimmunity, and cancer. Therefore, the sialic acid-Siglec axis is an emerging target to prevent or affect the course of several diseases. Chemical modifications of the natural sialic acid ligands have led to sialic acid mimetics (SAMs) with improved binding affinity and selectivity towards Siglecs. Recent progress in glycobiotechnology allows the presentation of these SAMs on nanoparticles, polymers, and living cells via bioorthogonal synthesis. These developments now enable the detailed study of the sialic acid-Siglec axis including its therapeutic potential as an immune modulator. PMID:27085506

  15. [Concentric changes in the visual field associated with GABA-mimetic antiepileptic agents].

    PubMed

    Nordmann, J P; Baulac, M; Van Egroo, C

    1999-05-01

    Bilateral visual field constriction has been recently reported in patients treated with vigabatrin. It has been considered that vigabatrin, a GABA agonist antiepileptic drug, was specifically responsible for this visual field defect. We present four observations sharing the same characteristics of chronic tunnel vision. Three patients had had vigabatrin but the fourth one received other antiepileptic drugs, progabide, an agonist of post-synaptic GABA receptors, and phenobarbital which interferes with GABA-A receptors. It is thus possible to hypothesize a retinal toxicity triggered by chronically increased GABA transmission. If this is confirmed, an accurate incidence of symptomatic and asymptomatic visual field constriction with GABA-mimetic drugs should be established, as well as the patients' profiles which are more at risk. Patients currently under this type of treatment should be checked by both manual and automatic perimetry every six months to one year. PMID:10365327

  16. New perspectives on exploitation of incretin peptides for the treatment of diabetes and related disorders

    PubMed Central

    Irwin, Nigel; Flatt, Peter R

    2015-01-01

    The applicability of stable gut hormones for the treatment of obesity-related diabetes is now undisputable. This is based predominantly on prominent and sustained glucose-lowering actions, plus evidence that these peptides can augment insulin secretion and pancreatic islet function over time. This review highlights the therapeutic potential of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), oxyntomodulin (OXM) and cholecystokinin (CCK) for obesity-related diabetes. Stable GLP-1 mimetics have already been successfully adopted into the diabetic clinic, whereas GIP, CCK and OXM molecules offer promise as potential new classes of antidiabetic drugs. Moreover, recent studies have shown improved therapeutic effects following simultaneous modulation of multiple receptor signalling pathways by combination therapy or use of dual/triple agonist peptides. However, timing and composition of injections may be important to permit interludes of beta-cell rest. The review also addresses the possible perils of incretin based drugs for treatment of prediabetes. Finally, the unanticipated utility of stable gut peptides as effective treatments for complications of diabetes, bone disorders, cognitive impairment and cardiovascular dysfunction is considered. PMID:26557956

  17. Rational design of tryptophan-rich antimicrobial peptides with enhanced antimicrobial activities and specificities.

    PubMed

    Yu, Hui-Yuan; Huang, Kuo-Chun; Yip, Bak-Sau; Tu, Chih-Hsiang; Chen, Heng-Li; Cheng, Hsi-Tsung; Cheng, Jya-Wei

    2010-11-01

    Trp-rich antimicrobial peptides play important roles in the host innate defense mechanism of many plants and animals. A series of short Trp-rich peptides derived from the C-terminal region of Bothrops asper myothoxin II, a Lys49 phospholipase A(2) (PLA(2)), were found to reproduce the antimicrobial activities of their parent molecule. Of these peptides, KKWRWWLKALAKK-designated PEM-2-was found to display improved activity against both Gram-positive and Gram-negative bacteria. To improve the antimicrobial activity of PEM-2 for potential clinical applications further, we determined the solution structure of PEM-2 bound to membrane-mimetic dodecylphosphocholine (DPC) micelles by two-dimensional NMR methods. The DPC micelle-bound structure of PEM-2 adopts an α-helical conformation and the positively charged residues are clustered together to form a hydrophilic patch. The surface electrostatic potential map indicates that two of the three tryptophan residues are packed against the peptide backbone and form a hydrophobic face with Leu7, Ala9, and Leu10. A variety of biophysical and biochemical experiments, including circular dichroism, fluorescence spectroscopy, and microcalorimetry, were used to show that PEM-2 interacted with negatively charged phospholipid vesicles and efficiently induced dye release from these vesicles, suggesting that the antimicrobial activity of PEM-2 could be due to interactions with bacterial membranes. Potent analogues of PEM-2 with enhanced antimicrobial and less pronounced hemolytic activities were designed with the aid of these structural studies. PMID:20865718

  18. Peptide inhibition of p22phox and Rubicon interaction as a therapeutic strategy for septic shock.

    PubMed

    Kim, Ye-Ram; Koh, Hyun-Jung; Kim, Jae-Sung; Yun, Jin-Seung; Jang, Kiseok; Lee, Joo-Youn; Jung, Jae U; Yang, Chul-Su

    2016-09-01

    Sepsis is a clinical syndrome that complicates severe infection and is characterized by the systemic inflammatory response syndrome (SIRS), is a life threatening disease characterized by inflammation of the entire body. Upon microbial infection, p22phox-gp91phox NADPH oxidase (NOX) complexes produce reactive oxygen species (ROS) that are critical for the elimination of invading microbes. However, excess production of ROS represents a key element in the cascade of deleterious processes in sepsis. We have previously reported direct crosstalk between autophagy and phagocytosis machineries by demonstrating that the Rubicon protein interacts with p22phox upon microbial infection, facilitating phagosomal trafficking of the p22phox-gp91phox NOX complex to induce a ROS burst, inflammatory cytokine production, and thereby, potent anti-microbial activities. Here, we showed N8 peptide, an N-terminal 8-amino acid peptide derived from p22phox, was sufficient for Rubicon interaction and thus, capable of robustly blocking the Rubicon-p22phox interaction and profoundly suppressing ROS and inflammatory cytokine production. Consequently, treatment with the Tat-N8 peptide or a N8 peptide-mimetic small-molecule dramatically reduced the mortality associated with Cecal-Ligation-and-Puncture-induced polymicrobial sepsis in mice. This study demonstrates a new anti-sepsis therapeutic strategy by blocking the crosstalk between autophagy and phagocytosis innate immunity machineries, representing a potential paradigm shift for urgently needed therapeutic intervention against this life-threatening SIRS. PMID:27267627

  19. Morphological Diversity and Polymorphism of Self-Assembling Collagen Peptides Controlled by Length of Hydrophobic Domains

    PubMed Central

    2015-01-01

    Synthetic collagen mimetic peptides are used to probe the role of hydrophobic forces in mediating protein self-assembly. Higher order association is an integral property of natural collagens, which assemble into fibers and meshes that comprise the extracellular matrix of connective tissues. The unique triple-helix fold fully exposes two-thirds of positions in the protein to solvent, providing ample opportunities for engineering interaction sites. Inclusion of just a few hydrophobic groups in a minimal peptide promotes a rich variety of self-assembly behaviors, resulting in hundred-nanometer to micron size nanodiscs and nanofibers. Morphology depends primarily on the length of hydrophobic domains. Peptide discs contain lipophilic domains capable of sequestering small hydrophobic dyes. Combining multiple peptide types result in composite structures of discs and fibers ranging from stars to plates-on-a-string. These systems provide valuable tools to shed insight into the fundamental principles underlying hydrophobicity-driven higher order protein association that will facilitate the design of self-assembling systems in biomaterials and nanomedical applications. PMID:25390880

  20. Smac mimetic triggers necroptosis in pancreatic carcinoma cells when caspase activation is blocked.

    PubMed

    Hannes, Sabine; Abhari, Behnaz Ahangarian; Fulda, Simone

    2016-09-28

    Evasion of apoptosis represents a key mechanism of treatment resistance of pancreatic cancer (PC) and contributes to the poor prognosis of this cancer type. Here, we report that induction of necroptosis is an alternative strategy to trigger programmed cell death in apoptosis-resistant PC cells. We show that the second mitochondrial activator of caspases (Smac) mimetic BV6 that antagonizes inhibitor of apoptosis (IAP) proteins induces necroptosis in PC cells in which apoptosis is blocked by the caspase inhibitor zVAD.fmk. Intriguingly, BV6 switches autocrine/paracrine production of tumor necrosis factor (TNF)α by PC cells into a death signal and also acts in concert with exogenously supplied TNFα to trigger necroptosis, when caspase activation is simultaneously blocked. BV6 stimulates TNFα production and formation of the receptor-interacting protein (RIP)1/RIP3-containing necrosome complex in PC cells. Knockdown of TNF receptor 1 (TNFR1) protects PC cells from BV6- or BV6/TNFα-mediated cell death, demonstrating that TNFα autocrine/paracrine signaling by PC cells contributes to BV6-induced necroptosis. Importantly, genetic silencing of receptor interacting protein kinase 3 (RIPK3) or mixed lineage kinase domain-like protein (MLKL) significantly rescues PC cells from BV6- or BV6/TNFα-induced cell death. Similarly, pharmacological inhibition of RIP1, RIP3 or MLKL significantly reduces BV6- or BV6/TNFα-stimulated cell death. By demonstrating that Smac mimetics can bypass resistance to apoptosis by triggering necroptosis as an alternative form of programmed cell death, our findings have important implications for the design of new treatment concepts for PC. PMID:27267809

  1. In Situ Enzymatically Generated Photoswitchable Oxidase Mimetics and Their Application for Colorimetric Detection of Glucose Oxidase.

    PubMed

    Cao, Gen-Xia; Wu, Xiu-Ming; Dong, Yu-Ming; Li, Zai-Jun; Wang, Guang-Li

    2016-01-01

    In this study, a simple and amplified colorimetric assay is developed for the detection of the enzymatic activity of glucose oxidase (GOx) based on in situ formation of a photoswitchable oxidase mimetic of PO₄(3-)-capped CdS quantum dots (QDs). GOx catalyzes the oxidation of 1-thio-β-d-glucose to give 1-thio-β-d-gluconic acid which spontaneously hydrolyzes to β-d-gluconic acid and H₂S; the generated H₂S instantly reacts with Cd(2+) in the presence of Na₃PO₄ to give PO₄(3-)-stabilized CdS QDs in situ. Under visible-light (λ ≥ 400 nm) stimulation, the PO₄(3-)-capped CdS QDs are a new style of oxidase mimic derived by producing some active species, such as h⁺, (•)OH, O₂(•-) and a little H₂O₂, which can oxidize the typical substrate (3,3,5,5-tetramethylbenzydine (TMB)) with a color change. Based on the GOx-triggered growth of the oxidase mimetics of PO₄(3-)-capped CdS QDs in situ, we developed a simple and amplified colorimetric assay to probe the enzymatic activity of GOx. The proposed method allowed the detection of the enzymatic activity of GOx over the range from 25 μg/L to 50 mg/L with a low detection limit of 6.6 μg/L. We believe the PO₄(3-)-capped CdS QDs generated in situ with photo-stimulated enzyme-mimicking activity may find wide potential applications in biosensors. PMID:27409598

  2. Inhibition of Salmonella enterica Biofilm Formation Using Small-Molecule Adenosine Mimetics

    PubMed Central

    Koopman, Jacob A.; Marshall, Joanna M.; Bhatiya, Aditi; Eguale, Tadesse; Kwiek, Jesse J.

    2014-01-01

    Biofilms have been widely implicated in chronic infections and environmental persistence of Salmonella enterica, facilitating enhanced colonization of surfaces and increasing the ability of the bacteria to be transmitted to new hosts. Salmonella enterica serovar Typhi biofilm formation on gallstones from humans and mice enhances gallbladder colonization and bacterial shedding, while Salmonella enterica serovar Typhimurium biofilms facilitate long-term persistence in a number of environments important to food, medical, and farming industries. Salmonella regulates expression of many virulence- and biofilm-related processes using kinase-driven pathways. Kinases play pivotal roles in phosphorylation and energy transfer in cellular processes and possess an ATP-binding pocket required for their functions. Many other cellular proteins also require ATP for their activity. Here we test the hypothesis that pharmacological interference with ATP-requiring enzymes utilizing adenosine mimetic compounds would decrease or inhibit bacterial biofilm formation. Through the screening of a 3,000-member ATP mimetic library, we identified a single compound (compound 7955004) capable of significantly reducing biofilm formation by S. Typhimurium and S. Typhi. The compound was not bactericidal or bacteriostatic toward S. Typhimurium or cytotoxic to mammalian cells. An ATP-Sepharose affinity matrix technique was used to discover potential protein-binding targets of the compound and identified GroEL and DeoD. Compound 7955004 was screened against other known biofilm-forming bacterial species and was found to potently inhibit biofilms of Acinetobacter baumannii as well. The identification of a lead compound with biofilm-inhibiting capabilities toward Salmonella provides a potential new avenue of therapeutic intervention against Salmonella biofilm formation, with applicability to biofilms of other bacterial pathogens. PMID:25313216

  3. Sodium chromate demonstrates some insulin-mimetic properties in the fruit fly Drosophila melanogaster.

    PubMed

    Perkhulyn, Natalia V; Rovenko, Bohdana M; Zvarych, Tetyana V; Lushchak, Oleh V; Storey, Janet M; Storey, Kenneth B; Lushchak, Volodymyr I

    2015-01-01

    The effects of food supplementation with sodium chromate at concentrations of 1-500 μM on development of Drosophila melanogaster larvae and food intake, carbohydrate and lipid pools in adult fruit flies were investigated. Food supplementation with hexavalent chromium (Na2CrO4) at high concentrations delayed larval development and decreased the percentage of larvae that pupated which indicated a relatively low toxicity. The supplement decreased glucose levels in fly hemolymph, but at concentrations of 5-25 μM increased fly carbohydrate reserves: hemolymph trehalose and whole body trehalose and glycogen. The data on parameters of carbohydrate metabolism show that chromate possesses some insulin-mimetic properties. The changes in metabolism of carbohydrates under chromate exposure were also accompanied by an increase in total lipid levels and in the portion of triacylglycerides among all lipids. Chromate addition to fly food did not affect male or female body mass, but reduced food consumption by females at all concentrations used, whereas in males only 500 μM chromate decreased food consumption. The data show that: (1) Cr(6+) has many of the same effects as Cr(3+) suggesting that it might be just as effective to treat diabetic states, likely as a result of intracellular reduction of Cr(6+) ions, and (2) the Drosophila model can be used to develop new approaches to investigate the molecular mechanisms of chromium as an insulin-mimetic. Although it is usually believed that hexavalent chromium possesses higher toxicity than the trivalent ion, due to its easier penetration into the cell, application of hexavalent chromium may substantially decrease the chromium doses needed to get the desired effects. PMID:25220772

  4. The characterization of decellularized human skeletal muscle as a blueprint for mimetic scaffolds.

    PubMed

    Wilson, Klaire; Terlouw, Abby; Roberts, Kevin; Wolchok, Jeffrey C

    2016-08-01

    The use of decellularized skeletal muscle (DSM) as a cell substrate and scaffold for the repair of volumetric muscle loss injuries has shown therapeutic promise. The performance of DSM materials motivated our interest in exploring the chemical and physical properties of this promising material. We suggest that these properties could serve as a blueprint for the development of next generation engineered materials with DSM mimetic properties. In this study, whole human lower limb rectus femoris (n = 10) and upper limb supraspinatus muscle samples (n = 10) were collected from both male and female tissue donors. Skeletal muscle samples were decellularized and nine property values, capturing key compositional, architectural, and mechanical properties, were measured and statistically analyzed. Mean values for each property were determined across muscle types and sexes. Additionally, the influence of muscle type (upper vs lower limb) and donor sex (male vs female) on each of the DSM material properties was examined. The data suggests that DSM materials prepared from lower limb rectus femoris samples have an increased modulus and contain a higher collagen content then upper limb supraspinatus muscles. Specifically, lower limb rectus femoris DSM material modulus and collagen content was approximately twice that of lower limb supraspinatus DSM samples. While muscle type did show some influence on material properties, we did not find significant trends related to sex. The material properties reported herein may be used as a blueprint for the data-driven design of next generation engineered scaffolds with muscle mimetic properties, as well as inputs for computational and physical models of skeletal muscle. PMID:27324779

  5. The BH3 Mimetic Obatoclax Accumulates in Lysosomes and Causes Their Alkalinization.

    PubMed

    Stamelos, Vasileios A; Fisher, Natalie; Bamrah, Harnoor; Voisey, Carolyn; Price, Joshua C; Farrell, William E; Redman, Charles W; Richardson, Alan

    2016-01-01

    Obatoclax belongs to a class of compounds known as BH3 mimetics which function as antagonists of Bcl-2 family apoptosis regulators. It has undergone extensive preclinical and clinical evaluation as a cancer therapeutic. Despite this, it is clear that obatoclax has additional pharmacological effects that contribute to its cytotoxic activity. It has been claimed that obatoclax, either alone or in combination with other molecularly targeted therapeutics, induces an autophagic form of cell death. In addition, obatoclax has been shown to inhibit lysosomal function, but the mechanism of this has not been elucidated. We have evaluated the mechanism of action of obatoclax in eight ovarian cancer cell lines. Consistent with its function as a BH3 mimetic, obatoclax induced apoptosis in three cell lines. However, in the remaining cell lines another form of cell death was evident because caspase activation and PARP cleavage were not observed. Obatoclax also failed to show synergy with carboplatin and paclitaxel, chemotherapeutic agents which we have previously shown to be synergistic with authentic Bcl-2 family antagonists. Obatoclax induced a profound accumulation of LC-3 but knockdown of Atg-5 or beclin had only minor effects on the activity of obatoclax in cell growth assays suggesting that the inhibition of lysosomal function rather than stimulation of autophagy may play a more prominent role in these cells. To evaluate how obatoclax inhibits lysosomal function, confocal microscopy studies were conducted which demonstrated that obatoclax, which contains two basic pyrrole groups, accumulates in lysosomes. Studies using pH sensitive dyes demonstrated that obatoclax induced lysosomal alkalinization. Furthermore, obatoclax was synergistic in cell growth/survival assays with bafilomycin and chloroquine, two other drugs which cause lysosomal alkalinization. These studies explain, for the first time, how obatoclax inhibits lysosomal function and suggest that lysosomal

  6. The BH3 Mimetic Obatoclax Accumulates in Lysosomes and Causes Their Alkalinization

    PubMed Central

    Stamelos, Vasileios A.; Fisher, Natalie; Bamrah, Harnoor; Voisey, Carolyn; Price, Joshua C.; Farrell, William E.; Redman, Charles W.; Richardson, Alan

    2016-01-01

    Obatoclax belongs to a class of compounds known as BH3 mimetics which function as antagonists of Bcl-2 family apoptosis regulators. It has undergone extensive preclinical and clinical evaluation as a cancer therapeutic. Despite this, it is clear that obatoclax has additional pharmacological effects that contribute to its cytotoxic activity. It has been claimed that obatoclax, either alone or in combination with other molecularly targeted therapeutics, induces an autophagic form of cell death. In addition, obatoclax has been shown to inhibit lysosomal function, but the mechanism of this has not been elucidated. We have evaluated the mechanism of action of obatoclax in eight ovarian cancer cell lines. Consistent with its function as a BH3 mimetic, obatoclax induced apoptosis in three cell lines. However, in the remaining cell lines another form of cell death was evident because caspase activation and PARP cleavage were not observed. Obatoclax also failed to show synergy with carboplatin and paclitaxel, chemotherapeutic agents which we have previously shown to be synergistic with authentic Bcl-2 family antagonists. Obatoclax induced a profound accumulation of LC-3 but knockdown of Atg-5 or beclin had only minor effects on the activity of obatoclax in cell growth assays suggesting that the inhibition of lysosomal function rather than stimulation of autophagy may play a more prominent role in these cells. To evaluate how obatoclax inhibits lysosomal function, confocal microscopy studies were conducted which demonstrated that obatoclax, which contains two basic pyrrole groups, accumulates in lysosomes. Studies using pH sensitive dyes demonstrated that obatoclax induced lysosomal alkalinization. Furthermore, obatoclax was synergistic in cell growth/survival assays with bafilomycin and chloroquine, two other drugs which cause lysosomal alkalinization. These studies explain, for the first time, how obatoclax inhibits lysosomal function and suggest that lysosomal

  7. The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

    PubMed Central

    2011-01-01

    Background The primary goal of current chemotherapy in hepatoblastoma (HB) is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergistic effects of this approach in HB cells and HB xenografts. Methods Viability was monitored in HB cells (HUH6 and HepT1) and fibroblasts treated with paclitaxel, ABT-737 and a combination of both in a MTT assay. HUH6 xenotransplants in NOD/LtSz-scid IL2Rγnull mice (NSG) were treated accordingly. Tumour volume and body weight were monitored. Xenografted tumours were analysed by histology and immunohistochemistry (Ki-67 and TUNEL assay). Results ABT-737 reduced viability in HUH6 and HepT1 cells cultures at concentrations above 1 μM and also enhanced the cytotoxic effect of paclitaxel when used in combination. Thereby paclitaxel could be reduced tenfold to achieve similar reduction of viability of tumour cells. In contrast no toxicity in fibroblasts was observed at the same regiments. Subcutaneous HB (HUH6) treated with paclitaxel (12 mg/kg body weight, n = 7) led to delayed tumour growth in the beginning of the experiment. However, tumour volume was similar to controls (n = 5) at day 25. Combination treatment with paclitaxel and ABT-737 (100 mg/kg, n = 8) revealed significantly 10 fold lower relative tumour volumes compared to control and paclitaxel groups. Paclitaxel dependent toxicity was observed in this mice strain. Conclusions Our results demonstrate enhancement of chemotherapy by using modulators of apoptosis. Further analyses should include improved pharmacological formulations of paclitaxel and BH3 mimetics in order to reduce toxicological effects. Sensitising HB to apoptosis

  8. Characterization of a Peptide Domain within the GB Virus C NS5A Phosphoprotein that Inhibits HIV Replication

    PubMed Central

    Xiang, Jinhua; McLinden, James H.; Chang, Qing; Jordan, Emma L.; Stapleton, Jack T.

    2008-01-01

    Background GBV-C infection is associated with prolonged survival in HIV-infected people and GBV-C inhibits HIV replication in co-infection models. Expression of the GBV-C nonstructural phosphoprotein 5A (NS5A) decreases surface levels of the HIV co-receptor CXCR4, induces the release of SDF-1 and inhibits HIV replication in Jurkat CD4+ T cell lines. Methodology/Principal Findings Jurkat cell lines stably expressing NS5A protein and peptides were generated and HIV replication in these cell lines assessed. HIV replication was significantly inhibited in all cell lines expressing NS5A amino acids 152–165. Substitution of an either alanine or glycine for the serine at position 158 (S158A or S158G) resulted in a significant decrease in the HIV inhibitory effect. In contrast, substituting a phosphomimetic amino acid (glutamic acid; S158E) inhibited HIV as well as the parent peptide. HIV inhibition was associated with lower levels of surface expression of the HIV co-receptor CXCR4 and increased release of the CXCR4 ligand, SDF-1 compared to control cells. Incubation of CD4+ T cell lines with synthetic peptides containing amino acids 152–167 or the S158E mutant peptide prior to HIV infection resulted in HIV replication inhibition compared to control peptides. Conclusions/Significance Expression of GBV-C NS5A amino acids 152–165 are sufficient to inhibit HIV replication in vitro, and the serine at position 158 appears important for this effect through either phosphorylation or structural changes in this peptide. The addition of synthetic peptides containing 152–167 or the S158E substitution to Jurkat cells resulted in HIV replication inhibition in vitro. These data suggest that GBV-C peptides or a peptide mimetic may offer a novel, cellular-based approach to antiretroviral therapy. PMID:18596910

  9. Engineering of a Novel Simplified Human Insulin-Like Peptide 5 Agonist.

    PubMed

    Patil, Nitin A; Hughes, Richard A; Rosengren, K Johan; Kocan, Martina; Ang, Sheng Yu; Tailhades, Julien; Separovic, Frances; Summers, Roger J; Grosse, Johannes; Wade, John D; Bathgate, Ross A D; Hossain, Mohammed Akhter

    2016-03-10

    Insulin-like peptide 5 (INSL5) has recently been discovered as only the second orexigenic gut hormone after ghrelin. As we have previously reported, INSL5 is extremely difficult to assemble and oxidize into its two-chain three-disulfide structure. The focus of this study was to generate structure-activity relationships (SARs) of INSL5 and use it to develop a potent and simpler INSL5 mimetic with RXFP4 agonist activity. A series of human and mouse INSL5 (hINSL5/mINSL5) analogues were designed and chemically synthesized, resulting in a chimeric INSL5 analogue exhibiting more than 10-fold higher potency (0.35 nM) at human RXFP4 compared with native hINSL5 (4.57 nM). The SAR study also identified a key residue (K(A15)) in the A-chain of mINSL5 that contributes to improved RXFP4 affinity and potency of mINSL5 compared with hINSL5. This knowledge ultimately led us to engineer a minimized hINSL5 mimetic agonist that retains native hINSL5-like RXFP4 affinity and potency at human RXFP4. This minimized analogue was synthesized in 17.5-fold higher yield and in less time compared with hINSL5. PMID:26824523

  10. Tumor-Penetrating Peptides

    PubMed Central

    Teesalu, Tambet; Sugahara, Kazuki N.; Ruoslahti, Erkki

    2013-01-01

    Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC), contains the integrin-binding RGD motif. RGD mediates tumor-homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR) motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular “zip code” of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies, and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is present in the

  11. Peptide-laden mesoporous silica nanoparticles with promoted bioactivity and osteo-differentiation ability for bone tissue engineering.

    PubMed

    Luo, Zuyuan; Deng, Yi; Zhang, Ranran; Wang, Mengke; Bai, Yanjie; Zhao, Qiang; Lyu, Yalin; Wei, Jie; Wei, Shicheng

    2015-07-01

    Combination of mesoporous silica materials and bioactive factors is a promising niche-mimetic solution as a hybrid bone substitution for bone tissue engineering. In this work, we have synthesized biocompatible silica-based nanoparticles with abundant mesoporous structure, and incorporated bone-forming peptide (BFP) derived from bone morphogenetic protein-7 (BMP-7) into the mesoporous silica nanoparticles (MSNs) to obtain a slow-release system for osteogenic factor delivery. The chemical characterization demonstrates that the small osteogenic peptide is encapsulated in the mesoporous successfully, and the nitrogen adsorption-desorption isotherms suggest that the peptide encapsulation has no influence on mesoporous structure of MSNs. In the cell experiment, the peptide-laden MSNs (p-MSNs) show higher MG-63 cell proliferation, spreading and alkaline phosphatase (ALP) activity than the bare MSNs, indicating good in vitro cytocompatibility. Simultaneously, the osteogenesis-related proteins expression and calcium mineral deposition disclose enhanced osteo-differentiation of human mesenchymal stem cells (hMSCs) under the stimulation of the p-MSNs, confirming that BFP released from MSNs could significantly promote the osteogenic differentiation of hMSCs, especially at 500μg/mL of p-MSNs concentration. The peptide-modified MSNs with better bioactivity and osteogenic differentiation make it a potential candidate as bioactive material for bone repairing, bone regeneration, and bio-implant coating applications. PMID:25969416

  12. Synthetic antimicrobial peptide design.

    PubMed

    Powell, W A; Catranis, C M; Maynard, C A

    1995-01-01

    To guide the design of potential plant pathogen-resistance genes, synthetic variants of naturally occurring antimicrobial gene products were evaluated. Five 20-amino acid (ESF1, ESF4, ESF5, ESF6, ESF13), one 18-amino acid (ESF12), and one 17-amino acid (ESF17) amphipathic peptide sequences were designed, synthesized, and tested with in vitro bioassays. Positive charges on the hydrophilic side of the peptide were shown to be essential for antifungal activity, yet the number of positive charges could be varied with little or no change in activity. The size could be reduced to 18 amino acids, but at 17 amino acids a significant reduction in activity was observed. ESF1, 5, 6, and 12 peptides were inhibitory to the germination of conidia from Cryphonectria parasitica, Fusarium oxysporum f. sp. lycopersici, and Septoria musiva but did not inhibit the germination of pollen from Castanea mollissima and Salix lucida. ESF12 also had no effect on the germination of Malus sylvestris and Lycopersicon esculentum pollen, but inhibited the growth of the bacteria Agrobacterium tumefaciens, Erwinia amylovora, and Pseudomonas syringae. The minimal inhibitory concentrations of the active ESF peptides were similar to those of the naturally occurring control peptides, magainin II and cecropin B. The significant differential in sensitivity between the microbes and plant cells indicated that the active ESF peptides are potentially useful models for designing plant pathogen-resistance genes. PMID:7579625

  13. Antimitotic peptides and depsipeptides.

    PubMed

    Hamel, Ernest; Covell, David G

    2002-01-01

    Tubulin is the target for an ever increasing number of unusual peptides and depsipeptides that were originally isolated from a wide variety of organisms. Since tubulin is the major component of cellular microtubules, which maintain cell shape in interphase and form the mitotic spindle, most of these compounds are highly toxic to mammalian cells. These peptides and depsipeptides disrupt cellular microtubules and prevent formation of a functional spindle, resulting in the accumulation of cultured cells in the G2/M phase of the cell cycle through specific inhibition of mitosis. At the biochemical level, the compounds all inhibit the assembly of tubulin into polymer and, in the cases where it has been studied, strongly suppress microtubule dynamics at low concentrations. In most cases the peptides and depsipeptides inhibit the binding of vinblastine and vincristine to tubulin in a noncompetitive manner, inhibit tubulin-dependent GTP hydrolysis, and interfere with nucleotide turnover at the exchangeable GTP site on beta-tubulin. Most of the peptides and depsipeptides induce tubulin to form oligomers of aberrant morphology, including tubulin rings that vary in diameter depending on the (depsi) peptide under study. The purpose of this review is to give an overview of the cellular, biochemical, in vivo, and SAR aspects of this group of compounds. We also summarize initial efforts by computer modeling to decipher a pharmacophore among the diverse structures of these peptides and depsipeptides. PMID:12678750

  14. Advances in peptidic and peptidomimetic-based approaches to inhibit STAT signaling in human diseases.

    PubMed

    Szelag, Malgorzata; Wesoly, Joanna; Bluyssen, Hans A R

    2016-01-01

    STATs promote fundamental cellular processes, marking them as convergence points of many oncogenic and inflammatory pathways. Therefore, aberrant activation of STAT signaling is implicated in a plethora of human diseases, like cancer, inflammation and auto-immunity. Identification of STAT-specific inhibitors is the topic of great practical importance, and various inhibitory strategies are being pursued. An interesting approach includes peptides and peptide-like biopolymers, because they allow the manipulation of STAT signaling without the transfer of genetic material. Phosphopeptides and peptidomimetics directly target STATs by inhibiting dimerization. Despite that a large number of efficient peptide- based STAT3-specific inhibitors have been reported to date, none of them was able to meet the pharmacological requirements to serve as a potent anti-cancer drug. The existing limitations, like metabolic instability and poor cell permeability during in vivo tests, excluded these macromolecules from further clinical development. To overcome these liabilities, in the last five years many advances have been made to develop next generation STAT-specific inhibitors. Here we discuss the pitfalls of current STAT inhibitory strategies and review the progress on the development of peptide-like prodrugs directly targeting STATs. Novel strategies involve screening of high-complexity libraries of random peptides, as specific STAT3 or STAT5 DNA-binding inhibitors, to construct cell permeable peptide aptamers and aptides for cancer therapy. Another new direction is synthesis of negative dominant α-helical mimetics of the STAT3 N-domain, preventing oligomerization on DNA. Moreover, construction of phosphopeptide conjugates with molecules mediating cellular uptake offers new therapeutic possibilities in treatment of cancer, asthma and allergy. PMID:26521960

  15. Bioinspired Hydroxyapatite/Poly(methyl methacrylate) Composite with a Nacre-Mimetic Architecture by a Bidirectional Freezing Method.

    PubMed

    Bai, Hao; Walsh, Flynn; Gludovatz, Bernd; Delattre, Benjamin; Huang, Caili; Chen, Yuan; Tomsia, Antoni P; Ritchie, Robert O

    2016-01-01

    Using a bidirectional freezing technique, combined with uniaxial pressing and in situ polymerization, "nacre-mimetic" hydroxyapatite/poly(methyl methacrylate) (PMMA) composites are developed by processing large-scale aligned lamellar ceramic scaffolds. Structural and mechanical characterization shows "brick-and-mortar" structures, akin to nacre, with interesting combinations of strength, stiffness, and work of fracture, which provide a pathway to making strong and tough lightweight materials. PMID:26554760

  16. Systematic Computation of Nonlinear Cellular and Molecular Dynamics with Low-Power CytoMimetic Circuits: A Simulation Study

    PubMed Central

    Papadimitriou, Konstantinos I.; Stan, Guy-Bart V.; Drakakis, Emmanuel M.

    2013-01-01

    This paper presents a novel method for the systematic implementation of low-power microelectronic circuits aimed at computing nonlinear cellular and molecular dynamics. The method proposed is based on the Nonlinear Bernoulli Cell Formalism (NBCF), an advanced mathematical framework stemming from the Bernoulli Cell Formalism (BCF) originally exploited for the modular synthesis and analysis of linear, time-invariant, high dynamic range, logarithmic filters. Our approach identifies and exploits the striking similarities existing between the NBCF and coupled nonlinear ordinary differential equations (ODEs) typically appearing in models of naturally encountered biochemical systems. The resulting continuous-time, continuous-value, low-power CytoMimetic electronic circuits succeed in simulating fast and with good accuracy cellular and molecular dynamics. The application of the method is illustrated by synthesising for the first time microelectronic CytoMimetic topologies which simulate successfully: 1) a nonlinear intracellular calcium oscillations model for several Hill coefficient values and 2) a gene-protein regulatory system model. The dynamic behaviours generated by the proposed CytoMimetic circuits are compared and found to be in very good agreement with their biological counterparts. The circuits exploit the exponential law codifying the low-power subthreshold operation regime and have been simulated with realistic parameters from a commercially available CMOS process. They occupy an area of a fraction of a square-millimetre, while consuming between 1 and 12 microwatts of power. Simulations of fabrication-related variability results are also presented. PMID:23393550

  17. Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids

    NASA Astrophysics Data System (ADS)

    Jin, Haibao; Jiao, Fang; Daily, Michael D.; Chen, Yulin; Yan, Feng; Ding, Yan-Huai; Zhang, Xin; Robertson, Ellen J.; Baer, Marcel D.; Chen, Chun-Long

    2016-07-01

    An ability to develop sequence-defined synthetic polymers that both mimic lipid amphiphilicity for self-assembly of highly stable membrane-mimetic 2D nanomaterials and exhibit protein-like functionality would revolutionize the development of biomimetic membranes. Here we report the assembly of lipid-like peptoids into highly stable, crystalline, free-standing and self-repairing membrane-mimetic 2D nanomaterials through a facile crystallization process. Both experimental and molecular dynamics simulation results show that peptoids assemble into membranes through an anisotropic formation process. We further demonstrated the use of peptoid membranes as a robust platform to incorporate and pattern functional objects through large side-chain diversity and/or co-crystallization approaches. Similar to lipid membranes, peptoid membranes exhibit changes in thickness upon exposure to external stimuli; they can coat surfaces in single layers and self-repair. We anticipate that this new class of membrane-mimetic 2D nanomaterials will provide a robust matrix for development of biomimetic membranes tailored to specific applications.

  18. High-order mimetic finite elements for the hydrostatic primitive equations on a cubed-sphere grid using Hamiltonian methods

    NASA Astrophysics Data System (ADS)

    Eldred, Christopher; Dubos, Thomas; Kritsikis, Evaggelos

    2016-04-01

    There has been a great deal of work in the past decade on the development of mimetic and conservative numerical schemes for atmospheric dynamical cores using Hamiltonian methods, such as Dynamico (Dubos et. al 2015). This model conserves mass, potential vorticity and total energy; and posses properties such as a curl-free pressure gradient that does not produce spurious vorticity. Unfortunately, the underlying finite-difference discretization scheme used in Dynamico has been shown to be inconsistent on general grids. An alternative scheme based on mimetic finite elements has been developed for the rotating shallow water equations that solves these accuracy issues but retains the desirable mimetic and conservation properties. Preliminary results on the extension of this scheme to the hydrostatic primitive equations are shown. The compatible 2D finite elements spaces are extended to compatible 3D spaces using tensor products, in a way that preserves their properties. It is shown that use of the same prognostic variables as Dynamico combined with a Lorenz staggering leads to a relatively simple formulation that allows conservation of total energy along with high-order accuracy.

  19. The SMAC mimetic, LCL-161, reduces survival in aggressive MYC-driven lymphoma while promoting susceptibility to endotoxic shock

    PubMed Central

    West, A C; Martin, B P; Andrews, D A; Hogg, S J; Banerjee, A; Grigoriadis, G; Johnstone, R W; Shortt, J

    2016-01-01

    Inhibitor of apoptosis proteins (IAPs) antagonize caspase activation and regulate death receptor signaling cascades. LCL-161 is a small molecule second mitochondrial activator of caspase (SMAC) mimetic, which both disengages IAPs from caspases and induces proteasomal degradation of cIAP-1 and -2, resulting in altered signaling through the NFκB pathway, enhanced TNF production and sensitization to apoptosis mediated by the extrinsic pathway. SMAC mimetics are undergoing clinical evaluation in a range of hematological malignancies. Burkitt-like lymphomas are hallmarked by a low apoptotic threshold, conveying sensitivity to a range of apoptosis-inducing stimuli. While evaluating LCL-161 in the Eμ-Myc model of aggressive Burkitt-like lymphoma, we noted unexpected resistance to apoptosis induction despite ‘on-target' IAP degradation and NFκB activation. Moreover, LCL-161 treatment of lymphoma-bearing mice resulted in apparent disease acceleration concurrent to augmented inflammatory cytokine-release in the same animals. Indiscriminate exposure of lymphoma patients to SMAC mimetics may therefore be detrimental due to both unanticipated prolymphoma effects and increased susceptibility to endotoxic shock. PMID:27043662

  20. The SMAC mimetic, LCL-161, reduces survival in aggressive MYC-driven lymphoma while promoting susceptibility to endotoxic shock.

    PubMed

    West, A C; Martin, B P; Andrews, D A; Hogg, S J; Banerjee, A; Grigoriadis, G; Johnstone, R W; Shortt, J

    2016-01-01

    Inhibitor of apoptosis proteins (IAPs) antagonize caspase activation and regulate death receptor signaling cascades. LCL-161 is a small molecule second mitochondrial activator of caspase (SMAC) mimetic, which both disengages IAPs from caspases and induces proteasomal degradation of cIAP-1 and -2, resulting in altered signaling through the NFκB pathway, enhanced TNF production and sensitization to apoptosis mediated by the extrinsic pathway. SMAC mimetics are undergoing clinical evaluation in a range of hematological malignancies. Burkitt-like lymphomas are hallmarked by a low apoptotic threshold, conveying sensitivity to a range of apoptosis-inducing stimuli. While evaluating LCL-161 in the Eμ-Myc model of aggressive Burkitt-like lymphoma, we noted unexpected resistance to apoptosis induction despite 'on-target' IAP degradation and NFκB activation. Moreover, LCL-161 treatment of lymphoma-bearing mice resulted in apparent disease acceleration concurrent to augmented inflammatory cytokine-release in the same animals. Indiscriminate exposure of lymphoma patients to SMAC mimetics may therefore be detrimental due to both unanticipated prolymphoma effects and increased susceptibility to endotoxic shock. PMID:27043662

  1. Inhibition of MARCH5 ubiquitin ligase abrogates MCL1-dependent resistance to BH3 mimetics via NOXA

    PubMed Central

    Subramanian, Aishwarya; Andronache, Adrian; Li, Yao-Cheng; Wade, Mark

    2016-01-01

    BH3 mimetic compounds induce tumor cell death through targeted inhibition of anti-apoptotic BCL2 proteins. Resistance to one such compound, ABT-737, is due to increased levels of anti-apoptotic MCL1. Using chemical and genetic approaches, we show that resistance to ABT-737 is abrogated by inhibition of the mitochondrial RING E3 ligase, MARCH5. Mechanistically, this is due to increased expression of pro-apoptotic BCL2 family member, NOXA, and is associated with MARCH5 regulation of MCL1 ubiquitylation and stability in a NOXA-dependent manner. MARCH5 expression contributed to an 8-gene signature that correlates with sensitivity to the preclinical BH3 mimetic, navitoclax. Furthermore, we observed a synthetic lethal interaction between MCL1 and MARCH5 in MCL1-dependent breast cancer cells. Our data uncover a novel level at which the BCL2 family is regulated; furthermore, they suggest targeting MARCH5-dependent signaling will be an effective strategy for treatment of BH3 mimetic-resistant tumors, even in the presence of high MCL1. PMID:26910119

  2. Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids.

    PubMed

    Jin, Haibao; Jiao, Fang; Daily, Michael D; Chen, Yulin; Yan, Feng; Ding, Yan-Huai; Zhang, Xin; Robertson, Ellen J; Baer, Marcel D; Chen, Chun-Long

    2016-01-01

    An ability to develop sequence-defined synthetic polymers that both mimic lipid amphiphilicity for self-assembly of highly stable membrane-mimetic 2D nanomaterials and exhibit protein-like functionality would revolutionize the development of biomimetic membranes. Here we report the assembly of lipid-like peptoids into highly stable, crystalline, free-standing and self-repairing membrane-mimetic 2D nanomaterials through a facile crystallization process. Both experimental and molecular dynamics simulation results show that peptoids assemble into membranes through an anisotropic formation process. We further demonstrated the use of peptoid membranes as a robust platform to incorporate and pattern functional objects through large side-chain diversity and/or co-crystallization approaches. Similar to lipid membranes, peptoid membranes exhibit changes in thickness upon exposure to external stimuli; they can coat surfaces in single layers and self-repair. We anticipate that this new class of membrane-mimetic 2D nanomaterials will provide a robust matrix for development of biomimetic membranes tailored to specific applications. PMID:27402325

  3. Impairment of antioxidant defense via glutathione depletion sensitizes acute lymphoblastic leukemia cells for Smac mimetic-induced cell death.

    PubMed

    Schoeneberger, H; Belz, K; Schenk, B; Fulda, S

    2015-07-30

    Evasion of apoptosis in pediatric acute lymphoblastic leukemia (ALL) is linked to aberrant expression of inhibitor of apoptosis (IAP) proteins and dysregulated redox homeostasis, rendering leukemic cells vulnerable to redox-targeting therapies. Here we discover that inhibition of antioxidant defenses via glutathione (GSH) depletion by buthionine sulfoximine (BSO) primes ALL cells for apoptosis induced by the Smac mimetic BV6 that antagonizes IAP proteins. Similarly, BSO cooperates with BV6 to induce cell death in patient-derived primary leukemic samples, underscoring the clinical relevance. In contrast, BSO does not sensitize non-malignant lymphohematopoietic cells from healthy donors toward BV6, pointing to some tumor selectivity. Mechanistically, both agents cooperate to stimulate reactive oxygen species (ROS) production, which is required for BSO/BV6-induced cell death, as ROS inhibitors (that is, N-acetylcysteine, MnTBAP, Trolox) significantly rescue cell death. Further, BSO and BV6 cooperate to trigger lipid peroxidation, which is necessary for cell death, as genetic or pharmacological blockage of lipid peroxidation by GSH peroxidase 4 (GPX4) overexpression or α-tocopherol significantly inhibits BSO/BV6-mediated cell death. Consistently, GPX4 knockdown or GPX4 inhibitor RSL3 enhances lipid peroxidation and cell death by BSO/BV6 cotreatment. The discovery of redox regulation of Smac mimetic-induced cell death has important implications for developing rational Smac mimetic-based combination therapies. PMID:25381820

  4. Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids

    PubMed Central

    Jin, Haibao; Jiao, Fang; Daily, Michael D.; Chen, Yulin; Yan, Feng; Ding, Yan-Huai; Zhang, Xin; Robertson, Ellen J.; Baer, Marcel D.; Chen, Chun-Long

    2016-01-01

    An ability to develop sequence-defined synthetic polymers that both mimic lipid amphiphilicity for self-assembly of highly stable membrane-mimetic 2D nanomaterials and exhibit protein-like functionality would revolutionize the development of biomimetic membranes. Here we report the assembly of lipid-like peptoids into highly stable, crystalline, free-standing and self-repairing membrane-mimetic 2D nanomaterials through a facile crystallization process. Both experimental and molecular dynamics simulation results show that peptoids assemble into membranes through an anisotropic formation process. We further demonstrated the use of peptoid membranes as a robust platform to incorporate and pattern functional objects through large side-chain diversity and/or co-crystallization approaches. Similar to lipid membranes, peptoid membranes exhibit changes in thickness upon exposure to external stimuli; they can coat surfaces in single layers and self-repair. We anticipate that this new class of membrane-mimetic 2D nanomaterials will provide a robust matrix for development of biomimetic membranes tailored to specific applications. PMID:27402325

  5. Membrane structure and conformational changes of the antibiotic heterodimeric peptide distinctin by solid-state NMR spectroscopy

    PubMed Central

    Resende, Jarbas M.; Moraes, Cléria Mendonça; Munhoz, Victor H. O.; Aisenbrey, Christopher; Verly, Rodrigo M.; Bertani, Philippe; Cesar, Amary; Piló-Veloso, Dorila; Bechinger, Burkhard

    2009-01-01

    The heterodimeric antimicrobial peptide distinctin is composed of 2 linear peptide chains of 22- and 25-aa residues that are connected by a single intermolecular S-S bond. This heterodimer has been considered to be a unique example of a previously unrecorded class of bioactive peptides. Here the 2 distinctin chains were prepared by chemical peptide synthesis in quantitative amounts and labeled with 15N, as well as 15N and 2H, at selected residues, respectively, and the heterodimer was formed by oxidation. CD spectroscopy indicates a high content of helical secondary structures when associated with POPC/POPG 3:1 vesicles or in membrane-mimetic environments. The propensity for helix formation follows the order heterodimer >chain 2 >chain 1, suggesting that peptide-peptide and peptide-lipid interactions both help in stabilizing this secondary structure. In a subsequent step the peptides were reconstituted into oriented phospholipid bilayers and investigated by 2H and proton-decoupled 15N solid-state NMR spectroscopy. Whereas chain 2 stably inserts into the membrane at orientations close to perfectly parallel to the membrane surface in the presence or absence of chain 1, the latter adopts a more tilted alignment, which further increases in the heterodimer. The data suggest that membrane interactions result in considerable conformational rearrangements of the heterodimer. Therefore, chain 2 stably anchors the heterodimer in the membrane, whereas chain 1 interacts more loosely with the bilayer. These structural observations are consistent with the antimicrobial activities when the individual chains are compared to the dimer. PMID:19805350

  6. Spectral marker for Cα damage in beta peptides.

    PubMed

    Green, Mandy C; Stelzleni, Sarah; Francisco, Joseph S

    2013-01-24

    The work in this article describes a spectral signature for the detection of a C(α) radical damaged peptide, which should enable the use of infrared spectroscopic methods to directly monitor oxidative events. Spectra for radical damaged peptides are computed with ab initio methods. The amide bands A, I, II, and III are analyzed for trends in the damage site. The spectral signature is found in a region (i.e., 1700-1620 cm(-1)) normally void of vibrational absorption bands from stable undamaged beta peptides. An analysis of the vibrational motions of the spectral signature is described. The uniqueness of the spectral signature is explored by an examination and comparison with C(α) monoradicals and polyradicals, as well as with other bioradicals that could act as spectral interferences. The identification of unique infrared spectral features for C(α) damage could have important implications in diagnostics for beta conformational peptides damaged by oxidative stress processes. PMID:23301948

  7. Enzyme-mimetic effects of gold@platinum nanorods on the antioxidant activity of ascorbic acid

    NASA Astrophysics Data System (ADS)

    Zhou, Yu-Ting; He, Weiwei; Wamer, Wayne G.; Hu, Xiaona; Wu, Xiaochun; Lo, Y. Martin; Yin, Jun-Jie

    2013-01-01

    Au@Pt nanorods were prepared by growing platinum nanodots on gold nanorods. Using electron spin resonance (ESR), we determined that the mechanisms for oxidation of ascorbic acid (AA) by Au@Pt nanorods and ascorbic acid oxidase (AAO) were kinetically similar and yielded similar products. In addition we observed that Au@Pt nanorods were stable with respect to temperature and pH. Using UV-VIS spectroscopy, the apparent kinetics of enzyme-mimetic activity of Au@Pt nanorods were studied and compared with the activity of AAO. With the help of ESR, we found that Au@Pt nanorods did not scavenge hydroxyl radicals but inhibited the antioxidant ability of AA for scavenging hydroxyl radicals produced by photoirradiating solutions containing titanium dioxide and zinc oxide. Moreover, the Au@Pt nanorods reduced the ability of AA to scavenge DPPH radicals and superoxide radicals. These results demonstrate that Au@Pt nanorods can reduce the antioxidant activity of AA. Therefore, it is necessary to consider the effects of using Pt nanoparticles together with other reducing agents or antioxidants such as AA due to the oxidase-like property of Au@Pt nanorods.Au@Pt nanorods were prepared by growing platinum nanodots on gold nanorods. Using electron spin resonance (ESR), we determined that the mechanisms for oxidation of ascorbic acid (AA) by Au@Pt nanorods and ascorbic acid oxidase (AAO) were kinetically similar and yielded similar products. In addition we observed that Au@Pt nanorods were stable with respect to temperature and pH. Using UV-VIS spectroscopy, the apparent kinetics of enzyme-mimetic activity of Au@Pt nanorods were studied and compared with the activity of AAO. With the help of ESR, we found that Au@Pt nanorods did not scavenge hydroxyl radicals but inhibited the antioxidant ability of AA for scavenging hydroxyl radicals produced by photoirradiating solutions containing titanium dioxide and zinc oxide. Moreover, the Au@Pt nanorods reduced the ability of AA to scavenge

  8. Electromembrane extraction of peptides.

    PubMed

    Balchen, Marte; Reubsaet, Léon; Pedersen-Bjergaard, Stig

    2008-06-20

    Rapid extraction of eight different peptides using electromembrane extraction (EME) was demonstrated for the first time. During an extraction time of 5 min, the model peptides migrated from a 500 microL aqueous acidic sample solution, through a thin supported liquid membrane (SLM) of an organic liquid sustained in the pores in the wall of a porous hollow fiber, and into a 25 microL aqueous acidic acceptor solution present inside the lumen of the hollow fiber. The driving force of the extraction was a 50 V potential sustained across the SLM, with the positive electrode in the sample and the negative electrode in the acceptor solution. The nature and the composition of the SLM were highly important for the EME process, and a mixture of 1-octanol and 15% di(2-ethylhexyl) phosphate was found to work properly. Using 1mM HCl as background electrolyte in the sample and 100 mM HCl in the acceptor solution, and agitation at 1050 rpm, enrichment up to 11 times was achieved. Recoveries were found to be dependent on the structure of the peptide, indicating that the polarity and the number of ionized groups were important parameters affecting the extraction efficiency. The experimental findings suggested that electromembrane extraction of peptides is possible and may be a valuable tool for future extraction of peptides. PMID:18479691

  9. Antimicrobial Peptides from Plants.

    PubMed

    Tam, James P; Wang, Shujing; Wong, Ka H; Tan, Wei Liang

    2015-01-01

    Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms. PMID:26580629

  10. Antimicrobial Peptides from Plants

    PubMed Central

    Tam, James P.; Wang, Shujing; Wong, Ka H.; Tan, Wei Liang

    2015-01-01

    Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms. PMID:26580629

  11. Peptide-based Inhibitors of Plk1 Polo-box Domain Containing Mono-anionic Phosphothreonine Esters and Their Pivaloyloxymethyl Prodrugs

    PubMed Central

    Qian, Wen-Jian; Park, Jung-Eun; Lim, Dan; Park, Suk-Youl; Lee, Ki -Won; Yaffe, Michael B.; Lee, Kyung S.; Burke, Terrence R.

    2013-01-01

    SUMMARY Binding of polo-like kinase 1 (Plk1) polo-box domains (PBDs) to phosphothreonine (pThr)/phosphoserine (pSer)-containing sequences is critical for the proper function of Plk1. Although high affinity synthetic pThr-containing peptides may be used to disrupt PBD function, the efficacy of such peptides in whole cell assays has been poor. This potentially reflects limited cell membrane permeability arising in part from the di-anionic nature of the phosphoryl group. In our current paper we report five-mer peptides containing mono-anionic pThr phosphoryl esters that exhibit single-digit nanomolar PBD binding affinities in extracellular assays and improved antimitotic efficacies in whole cell assays. The cellular efficacies of these peptides have been further enhanced by the first application of bio-reversible pivaloyloxymethyl (POM) phosphoryl protection to a pThr-containing polypeptide. Our findings may redefine structural parameters for the development of PBD-binding peptides and peptide mimetics. PMID:24120332

  12. Synthetic antibiofilm peptides.

    PubMed

    de la Fuente-Núñez, César; Cardoso, Marlon Henrique; de Souza Cândido, Elizabete; Franco, Octavio Luiz; Hancock, Robert E W

    2016-05-01

    Bacteria predominantly exist as multicellular aggregates known as biofilms that are associated with at least two thirds of all infections and exhibit increased adaptive resistance to conventional antibiotic therapies. Therefore, biofilms are major contributors to the global health problem of antibiotic resistance, and novel approaches to counter them are urgently needed. Small molecules of the innate immune system called host defense peptides (HDPs) have emerged as promising templates for the design of potent, broad-spectrum antibiofilm agents. Here, we review recent developments in the new field of synthetic antibiofilm peptides, including mechanistic insights, synergistic interactions with available antibiotics, and their potential as novel antimicrobials against persistent infections caused by biofilms. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. PMID:26724202

  13. Signal peptide of cellulase.

    PubMed

    Yan, Shaomin; Wu, Guang

    2014-06-01

    Cellulase is an enzyme playing a crucial role in biotechnology industries ranging from textile to biofuel because of tremendous amount of cellulose produced in plant. In order to improve cellulase productivity, huge resource has been spent in search for good cellulases from microorganism in remote areas and in creation of ideal cellulase by engineering. However, not much attention is given to the secretion of cellulases from cell into extracellular space, where a cellulase plays its enzymatic role. In this minireview, the signal peptides, which lead secreted proteins to specific secretion systems and scatter in literature, are reviewed. The patterns of signal peptides are checked against 4,101 cellulases documented in UniProtKB, the largest protein database in the world, to determine how these cellulases are secreted. Simultaneous review on both literature and cellulases from the database not only provides updated knowledge on signal peptides but also indicates the gap in our research. PMID:24743986

  14. Gene Transcriptional and Metabolic Profile Changes in Mimetic Aging Mice Induced by D-Galactose

    PubMed Central

    Zhou, Yue-Yue; Zhu, Xiao-Juan; Li, Rong-Hua; Mu, Chang-Kao; Wang, Chun-Lin; Song, Wei-Wei

    2015-01-01

    D-galactose injection has been shown to induce many changes in mice that represent accelerated aging. This mouse model has been widely used for pharmacological studies of anti-aging agents. The underlying mechanism of D-galactose induced aging remains unclear, however, it appears to relate to glucose and 1ipid metabolic disorders. Currently, there has yet to be a study that focuses on investigating gene expression changes in D-galactose aging mice. In this study, integrated analysis of gas chromatography/mass spectrometry-based metabonomics and gene expression profiles was used to investigate the changes in transcriptional and metabolic profiles in mimetic aging mice injected with D-galactose. Our findings demonstrated that 48 mRNAs were differentially expressed between control and D-galactose mice, and 51 potential biomarkers were identified at the metabolic level. The effects of D-galactose on aging could be attributed to glucose and 1ipid metabolic disorders, oxidative damage, accumulation of advanced glycation end products (AGEs), reduction in abnormal substance elimination, cell apoptosis, and insulin resistance. PMID:26176541

  15. A Multinuclear Metal Complex Based DNase-Mimetic Artificial Enzyme: Matrix Cleavage for Combating Bacterial Biofilms.

    PubMed

    Chen, Zhaowei; Ji, Haiwei; Liu, Chaoqun; Bing, Wei; Wang, Zhenzhen; Qu, Xiaogang

    2016-08-26

    Extracellular DNA (eDNA) is an essential structural component during biofilm formation, including initial bacterial adhesion, subsequent development, and final maturation. Herein, the construction of a DNase-mimetic artificial enzyme (DMAE) for anti-biofilm applications is described. By confining passivated gold nanoparticles with multiple cerium(IV) complexes on the surface of colloidal magnetic Fe3 O4  /SiO2 core/shell particles, a robust and recoverable artificial enzyme with DNase-like activity was obtained, which exhibited high cleavage ability towards both model substrates and eDNA. Compared to the high environmental sensitivity of natural DNase in anti-biofilm applications, DMAE exhibited a much better operational stability and easier recoverability. When DMAE was coated on substratum surfaces, biofilm formation was inhibited for prolonged periods of time, and the DMAE excelled in the dispersion of established biofilms of various ages. Finally, the presence of DMAE remarkably potentiated the efficiency of traditional antibiotics to kill biofilm-encased bacteria and eradiate biofilms. PMID:27484616

  16. Mimetic biomembrane-AuNPs-graphene hybrid as matrix for enzyme immobilization and bioelectrocatalysis study.

    PubMed

    Wang, Tianshu; Liu, Jiyang; Ren, Jiangtao; Wang, Jin; Wang, Erkang

    2015-10-01

    A hybrid composite constructed of phospholipids bilayer membrane, gold nanoparticles and graphene was prepared and used as matrices for microperoxidase-11 (MP11) immobilization. The direct electrochemistry and corresponding bioelectrocatalysis of the enzyme electrode was further investigated. Phospholipid bilayer membrane protected gold nanoparticles (AuNPs) were assembled on polyelectrolyte functionalized graphene sheets through electrostatic attraction to form a hybrid bionanocomposite. Owing to the biocompatible microenvironment provided by the mimetic biomembrane, microperoxidase-11 entrapped in this matrix well retained its native structure and exhibited high bioactivity. Moreover, the AuNPs-graphene assemblies could efficiently promote the direct electron transfer between the immobilized MP11 and the substrate electrode. The as-prepared enzyme electrode presented good direct electrochemistry and electrocatalytic responses to the reduction of hydrogen peroxide (H2O2). The resulting H2O2 biosensor showed a wide linear range (2.0×10(-5)-2.8×10(-4) M), a low detection limit (2.6×10(-6) M), good reproducibility and stability. Furthermore, this sensor was used for real-time detection of H2O2 dynamically released from the tumor cells MCF-7 in response to a pro-inflammatory stimulant. PMID:26078181

  17. Graphene-Based Nanomaterials as Efficient Peroxidase Mimetic Catalysts for Biosensing Applications: An Overview.

    PubMed

    Garg, Bhaskar; Bisht, Tanuja; Ling, Yong-Chien

    2015-01-01

    "Artificial enzymes", a term coined by Breslow for enzyme mimics is an exciting and promising branch of biomimetic chemistry aiming to imitate the general and essential principles of natural enzymes using a variety of alternative materials including heterogeneous catalysts. Peroxidase enzymes represent a large family of oxidoreductases that typically catalyze biological reactions with high substrate affinity and specificity under relatively mild conditions and thus offer a wide range of practical applications in many areas of science. The increasing understanding of general principles as well as intrinsic drawbacks such as low operational stability, high cost, difficulty in purification and storage, and sensitivity of catalytic activity towards atmospheric conditions of peroxidases has triggered a dynamic field in nanotechnology, biochemical, and material science that aims at joining the better of three worlds by combining the concept adapted from nature with the processability of catalytically active graphene-based nanomaterials (G-NMs) as excellent peroxidase mimetic catalysts. This comprehensive review discusses an up-to-date synthesis, kinetics, mechanisms, and biosensing applications of a variety of G-NMs that have been explored as promising catalysts to mimic natural peroxidases. PMID:26248071

  18. Species limits in polymorphic mimetic Eniclases net-winged beetles from New Guinean mountains (Coleoptera, Lycidae)

    PubMed Central

    Bocek, Matej; Bocak, Ladislav

    2016-01-01

    Abstract Species delimitation was compared in a group of closely related lineages of aposematically colored Eniclases (Coleoptera, Lycidae) using morphology, genetic distances, and Bayesian implementation of the Poisson Tree Processes model. A high diversity of net-winged beetles was found in previously unsampled regions of New Guinea and ten new species are described: Eniclases bicolor sp. n., Eniclases bokondinensis sp. n., Eniclases brancuccii sp. n., Eniclases elelimensis sp. n., Eniclases infuscatus sp. n., Eniclases niger sp. n., Eniclases pseudoapertus sp. n., Eniclases pseudoluteolus sp. n., Eniclases tikapurensis sp. n., and Eniclases variabilis sp. n. Different levels of genetic and morphological diversification were identified in various sister-species pairs. As a result, both morphological and molecular analyses are used to delimit species. Sister-species with uncorrected pairwise genetic divergence as low as 0.45% were morphologically distinct not only in color pattern, but also in the relative size of eyes. Conversely, differences in color pattern regardless of their magnitude did not necessarily indicate genetic distance and intraspecific mimicry polymorphism was common. Additionally, genetic divergence without morphological differentiation was detected in one sister-species pair. Low dispersal propensity, diverse mimicry patterns, and mimetic polymorphism resulted in complex diversification of Eniclases and uncertain species delimitation in recently diversified lineages. PMID:27408550

  19. A superoxide dismutase/catalase mimetic nanomedicine for targeted therapy of inflammatory bowel disease.

    PubMed

    Zhang, Qixiong; Tao, Hui; Lin, Yongyao; Hu, Ying; An, Huijie; Zhang, Dinglin; Feng, Shibin; Hu, Houyuan; Wang, Ruibing; Li, Xiaohui; Zhang, Jianxiang

    2016-10-01

    Oxidative stress, resulting from excessive generation of reactive oxygen species (ROS), plays a pivotal role in the initiation and progression of inflammatory bowel disease (IBD). To develop an efficacious and safe nanotherapy against IBD, we designed and developed a superoxide dismutase/catalase mimetic nanomedicine comprising a hydrogen peroxide-eliminating nanomatrix and a free radical scavenger Tempol (Tpl). To this end, an oxidation-responsive β-cyclodextrin material (OxbCD) was synthesized, and a Tpl-loaded OxbCD nanoparticle (Tpl/OxbCD NP) was produced. Hydrolysis of OxbCD NP could be triggered by hydrogen peroxide, leading to on-demand release of loaded Tpl molecules from Tpl/OxbCD NP. OxbCD NP was able to efficiently accumulate in the inflamed colon in mice, thereby dramatically reducing nonspecific distribution after oral delivery. In three mouse colitis models, oral administration of Tpl/OxbCD NP notably mitigated manifestations relevant to colitis, and significantly suppressed expression of proinflammatory mediators, with the efficacy superior over free Tpl or a control nanomedicine based on poly(lactide-co-glycolide) (PLGA). Accordingly, by scavenging multiple components of ROS, Tpl/OxbCD NP may effectively reduce ulcerative colitis in mice, and it can be intensively developed as a translational nanomedicine for the management of IBD and other inflammatory diseases. PMID:27525680

  20. Population genomics of parallel hybrid zones in the mimetic butterflies, H. melpomene and H. erato.

    PubMed

    Nadeau, Nicola J; Ruiz, Mayté; Salazar, Patricio; Counterman, Brian; Medina, Jose Alejandro; Ortiz-Zuazaga, Humberto; Morrison, Anna; McMillan, W Owen; Jiggins, Chris D; Papa, Riccardo

    2014-08-01

    Hybrid zones can be valuable tools for studying evolution and identifying genomic regions responsible for adaptive divergence and underlying phenotypic variation. Hybrid zones between subspecies of Heliconius butterflies can be very narrow and are maintained by strong selection acting on color pattern. The comimetic species, H. erato and H. melpomene, have parallel hybrid zones in which both species undergo a change from one color pattern form to another. We use restriction-associated DNA sequencing to obtain several thousand genome-wide sequence markers and use these to analyze patterns of population divergence across two pairs of parallel hybrid zones in Peru and Ecuador. We compare two approaches for analysis of this type of data-alignment to a reference genome and de novo assembly-and find that alignment gives the best results for species both closely (H. melpomene) and distantly (H. erato, ∼15% divergent) related to the reference sequence. Our results confirm that the color pattern controlling loci account for the majority of divergent regions across the genome, but we also detect other divergent regions apparently unlinked to color pattern differences. We also use association mapping to identify previously unmapped color pattern loci, in particular the Ro locus. Finally, we identify a new cryptic population of H. timareta in Ecuador, which occurs at relatively low altitude and is mimetic with H. melpomene malleti. PMID:24823669

  1. Population genomics of parallel hybrid zones in the mimetic butterflies, H. melpomene and H. erato

    PubMed Central

    Ruiz, Mayté; Salazar, Patricio; Counterman, Brian; Medina, Jose Alejandro; Ortiz-Zuazaga, Humberto; Morrison, Anna; Papa, Riccardo

    2014-01-01

    Hybrid zones can be valuable tools for studying evolution and identifying genomic regions responsible for adaptive divergence and underlying phenotypic variation. Hybrid zones between subspecies of Heliconius butterflies can be very narrow and are maintained by strong selection acting on color pattern. The comimetic species, H. erato and H. melpomene, have parallel hybrid zones in which both species undergo a change from one color pattern form to another. We use restriction-associated DNA sequencing to obtain several thousand genome-wide sequence markers and use these to analyze patterns of population divergence across two pairs of parallel hybrid zones in Peru and Ecuador. We compare two approaches for analysis of this type of data—alignment to a reference genome and de novo assembly—and find that alignment gives the best results for species both closely (H. melpomene) and distantly (H. erato, ∼15% divergent) related to the reference sequence. Our results confirm that the color pattern controlling loci account for the majority of divergent regions across the genome, but we also detect other divergent regions apparently unlinked to color pattern differences. We also use association mapping to identify previously unmapped color pattern loci, in particular the Ro locus. Finally, we identify a new cryptic population of H. timareta in Ecuador, which occurs at relatively low altitude and is mimetic with H. melpomene malleti. PMID:24823669

  2. Fabrication of cell outer membrane mimetic polymer brush on polysulfone surface via RAFT technique

    NASA Astrophysics Data System (ADS)

    Ma, Qian; Zhang, Hui; Zhao, Jiang; Gong, Yong-Kuan

    2012-10-01

    Cell membrane mimetic antifouling polymer brush was grown on polysulfone (PSF) membrane by surface-induced reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC). The RAFT agent immobilized PSF substrate was prepared by successive chloromethylation, amination with ethylenediamine (EDA) and amidation of the amine group of grafted EDA with the carboxylic group of 4-cyanopentanoic acid dithiobenzoate (CPAD). The surface RAFT polymerization of MPC was initiated in aqueous solution by 4,4‧-azobis-4-cyanopentanoic acid (ACPA). The formation of PMPC brush coating is evidenced by X-ray photoelectron spectroscopy and water contact angle measurements. The degree of polymerization of PMPC and the polymer grafting density were calculated from the high resolution XPS spectra. The platelet adhesion and protein adsorption results showed that the PMPC-grafted PSF surface has excellent antifouling ability to resist platelet adhesion completely and suppress protein adsorption significantly. This biomimetic and bio-friendly surface RAFT polymerization strategy could be promising for a variety of biomedical applications.

  3. Partial Complementarity of the Mimetic Yellow Bar Phenotype in Heliconius Butterflies

    PubMed Central

    Maroja, Luana S.; Alschuler, Rebecca; McMillan, W. Owen; Jiggins, Chris D.

    2012-01-01

    Heliconius butterflies are an excellent system for understanding the genetic basis of phenotypic change. Here we document surprising diversity in the genetic control of a common phenotype. Two disjunct H. erato populations have each recruited the Cr and/or Sd loci that control similar yellow hindwing patterns, but the alleles involved partially complement one another indicating either multiple origins for the patterning alleles or developmental drift in genetic control of similar patterns. We show that in these H. erato populations cr and sd are epistatically interacting and that the parental origin of alleles can explain phenotypes of backcross individuals. In contrast, mimetic H. melpomene populations with identical phenotypes (H. m. rosina and H. m. amaryllis) do not show genetic complementation (F1s and F2s are phenotypically identical to parentals). Finally, we report hybrid female inviability in H. m. melpomene × H. m. rosina crosses (previously only female infertility had been reported) and presence of standing genetic variation for alternative color alleles at the Yb locus in true breeding H. melpomene melpomene populations (expressed when in a different genomic background) that could be an important source of variation for the evolution of novel phenotypes or a result of developmental drift. Although recent work has emphasized the simple genetic control of wing pattern in Heliconius, we show there is underlying complexity in the allelic variation and epistatic interactions between major patterning loci. PMID:23119074

  4. Partial complementarity of the mimetic yellow bar phenotype in Heliconius butterflies.

    PubMed

    Maroja, Luana S; Alschuler, Rebecca; McMillan, W Owen; Jiggins, Chris D

    2012-01-01

    Heliconius butterflies are an excellent system for understanding the genetic basis of phenotypic change. Here we document surprising diversity in the genetic control of a common phenotype. Two disjunct H. erato populations have each recruited the Cr and/or Sd loci that control similar yellow hindwing patterns, but the alleles involved partially complement one another indicating either multiple origins for the patterning alleles or developmental drift in genetic control of similar patterns. We show that in these H. erato populations cr and sd are epistatically interacting and that the parental origin of alleles can explain phenotypes of backcross individuals. In contrast, mimetic H. melpomene populations with identical phenotypes (H. m. rosina and H. m. amaryllis) do not show genetic complementation (F(1)s and F(2)s are phenotypically identical to parentals). Finally, we report hybrid female inviability in H. m. melpomene × H. m. rosina crosses (previously only female infertility had been reported) and presence of standing genetic variation for alternative color alleles at the Yb locus in true breeding H. melpomene melpomene populations (expressed when in a different genomic background) that could be an important source of variation for the evolution of novel phenotypes or a result of developmental drift. Although recent work has emphasized the simple genetic control of wing pattern in Heliconius, we show there is underlying complexity in the allelic variation and epistatic interactions between major patterning loci. PMID:23119074

  5. Tumor-targeted delivery of paclitaxel using low density lipoprotein-mimetic solid lipid nanoparticles.

    PubMed

    Kim, Jin-Ho; Kim, Youngwook; Bae, Ki Hyun; Park, Tae Gwan; Lee, Jung Hee; Park, Keunchil

    2015-04-01

    Water-insoluble anticancer drugs, including paclitaxel, present severe clinical side effects when administered to patients, primarily associated with the toxicity of reagents used to solubilize the drugs. In efforts to develop alternative formulations of water-insoluble anticancer drugs suitable for intravenous administration, we developed biocompatible anticancer therapeutic solid lipid nanoparticles (SLNs), mimicking the structure and composition of natural particles, low-density lipoproteins (LDLs), for tumor-targeted delivery of paclitaxel. These therapeutic nanoparticles contained water-insoluble paclitaxel in the core with tumor-targeting ligand covalently conjugated on the polyethylene glycol (PEG)-modified surface (targeted PtSLNs). In preclinical human cancer xenograft mouse model studies, the paclitaxel-containing tumor-targeting SLNs exhibited pronounced in vivo stability and enhanced biocompatibility. Furthermore, these SLNs had superior antitumor activity to in-class nanoparticular therapeutics in clinical use (Taxol and Genexol-PM) and yielded long-term complete responses. The in vivo targeted antitumor activities of the SLN formulations in a mouse tumor model suggest that LDL-mimetic SLN formulations can be utilized as a biocompatible, tumor-targeting platform for the delivery of various anticancer therapeutics. PMID:25686010

  6. Hypoxia-mimetic effects in the secretome of human preadipocytes and adipocytes.

    PubMed

    Rosenow, Anja; Noben, Jean-Paul; Bouwman, Freek G; Mariman, Edwin C M; Renes, Johan

    2013-12-01

    White adipose tissue (WAT) regulates energy metabolism by secretion of proteins with endocrine and paracrine effects. Dysregulation of the secretome of obesity-associated enlarged WAT may lead to obesity-related disorders. This can be caused by hypoxia as a result of poorly vascularized WAT. The effect of hypoxia on the secretome of human (pre)adipocytes is largely unknown. Therefore, we investigated the effect of CoCl2, a hypoxia mimetic, on the secretome of human SGBS (pre)adipocytes by a proteomics approach combined with bioinformatic analysis. In addition, regulation of protein secretion was examined by protein turnover experiments. As such, secretome changes were particularly associated with protein down-regulation and extracellular matrix protein dysregulation. The observed up-regulation of collagens in adipocytes may be essential for cell survival while down-regulation of collagens in preadipocytes may indicate a disturbed differentiation process. These CoCl2-induced changes reflect WAT dysfunction that ultimately may lead to obesity-associated complications. In addition, 9 novel adipocyte secreted proteins were identified from which 6 were regulated by CoCl2. Mass spectrometry data have been deposited to the ProteomeXchange with identifier PXD000162. PMID:24140569

  7. Ferroportin mediates the intestinal absorption of iron from a nanoparticulate ferritin core mimetic in mice.

    PubMed

    Aslam, Mohamad F; Frazer, David M; Faria, Nuno; Bruggraber, Sylvaine F A; Wilkins, Sarah J; Mirciov, Cornel; Powell, Jonathan J; Anderson, Greg J; Pereira, Dora I A

    2014-08-01

    The ferritin core is composed of fine nanoparticulate Fe(3+) oxohydroxide, and we have developed a synthetic mimetic, nanoparticulate Fe(3+) polyoxohydroxide (nanoFe(3+)). The aim of this study was to determine how dietary iron derived in this fashion is absorbed in the duodenum. Following a 4 wk run-in on an Fe-deficient diet, mice with intestinal-specific disruption of the Fpn-1 gene (Fpn-KO), or littermate wild-type (WT) controls, were supplemented with Fe(2+) sulfate (FeSO4), nanoFe(3+), or no added Fe for a further 4 wk. A control group was Fe sufficient throughout. Direct intestinal absorption of nanoFe(3+) was investigated using isolated duodenal loops. Our data show that FeSO4 and nanoFe(3+) are equally bioavailable in WT mice, and at wk 8 the mean ± SEM hemoglobin increase was 18 ± 7 g/L in the FeSO4 group and 30 ± 5 g/L in the nanoFe(3+) group. Oral iron failed to be utilized by Fpn-KO mice and was retained in enterocytes, irrespective of the iron source. In summary, although nanoFe(3+) is taken up directly by the duodenum its homeostasis is under the normal regulatory control of dietary iron absorption, namely via ferroportin-dependent efflux from enterocytes, and thus offers potential as a novel oral iron supplement. PMID:24776745

  8. SMG1 and NIK regulate apoptosis induced by Smac mimetic compounds

    PubMed Central

    Cheung, H H; St Jean, M; Beug, S T; Lejmi-Mrad, R; LaCasse, E; Baird, S D; Stojdl, D F; Screaton, R A; Korneluk, R G

    2011-01-01

    Smac mimetic compounds (SMCs) are experimental small molecules that induce tumour necrosis factor alpha (TNFα)-dependent cancer cell death by targeting the inhibitor of apoptosis proteins. However, many cancer cell lines are resistant to SMC-mediated apoptosis despite the presence of TNFα. To add insight into the mechanism of SMC-resistance, we used functional siRNA-based kinomic and focused chemical screens and identified suppressor of morphogenesis in genitalia-1 (SMG1) and NF-κB-inducing kinase (NIK) as novel protective factors. Both SMG1 and NIK prevent SMC-mediated apoptosis likely by maintaining FLICE inhibitory protein (c-FLIP) levels to suppress caspase-8 activation. In SMC-resistant cells, the accumulation of NIK upon SMC treatment enhanced the activity of both the classical and alternative nuclear factor-κB pathways, and increased c-FLIP mRNA levels. In parallel, persistent SMG1 expression in SMC-resistant cells repressed SMC-mediated TNFα-induced JNK activation and c-FLIP levels were sustained. Importantly, SMC-resistance is overcome by depleting NIK and SMG1, which appear to facilitate the downregulation of c-FLIP in response to SMC and TNFα treatment, leading to caspase-8-dependent apoptosis. Collectively, these data show that SMG1 and NIK function as critical repressors of SMC-mediated apoptosis by potentially converging on the regulation of c-FLIP metabolism. PMID:21490678

  9. Smac Mimetic Compounds Potentiate Interleukin-1β-mediated Cell Death*

    PubMed Central

    Cheung, Herman H.; Beug, Shawn T.; St. Jean, Martine; Brewster, Audrey; Kelly, N. Lynn; Wang, Shaomeng; Korneluk, Robert G.

    2010-01-01

    Smac mimetic compounds (SMCs) potentiate TNFα-mediated cancer cell death by targeting the inhibitor of apoptosis (IAP) proteins. In addition to TNFα, the tumor microenvironment is exposed to a number of pro-inflammatory cytokines, including IL-1β. Here, we investigated the potential impact of IL-1β on SMC-mediated death of cancer cells. Synergy was seen in a subset of a diverse panel of 21 cancer cell lines to the combination of SMC and IL-1β treatment, which required IL-1β-induced activation of the NF-κB pathway. Elevated NF-κB activity resulted in the production of TNFα, which led to apoptosis dependent on caspase-8 and RIP1. In addition, concurrent silencing of cIAP1, cIAP2, and X-linked IAP by siRNA was most effective for triggering IL-1β-mediated cell death. Importantly, SMC-resistant cells that produced TNFα in response to IL-1β treatment were converted to an SMC-sensitive phenotype by c-FLIP knockdown. Reciprocally, ectopic expression of c-FLIP blocked cell death caused by combined SMC and IL-1β treatment in sensitive cancer cells. Together, our study indicates that a positive feed-forward loop by pro-inflammatory cytokines can be exploited by SMCs to induce apoptosis in cancer cells. PMID:20956527

  10. Heparan sulfate mimetic PG545-mediated antilymphoma effects require TLR9-dependent NK cell activation.

    PubMed

    Brennan, Todd V; Lin, Liwen; Brandstadter, Joshua D; Rendell, Victoria R; Dredge, Keith; Huang, Xiaopei; Yang, Yiping

    2016-01-01

    Heparan sulfate (HS) is an essential component of the extracellular matrix (ECM), which serves as a barrier to tumor invasion and metastasis. Heparanase promotes tumor growth by cleaving HS chains of proteoglycan and releasing HS-bound angiogenic growth factors and facilitates tumor invasion and metastasis by degrading the ECM. HS mimetics, such as PG545, have been developed as antitumor agents and are designed to suppress angiogenesis and metastasis by inhibiting heparanase and competing for the HS-binding domain of angiogenic growth factors. However, how PG545 exerts its antitumor effect remains incompletely defined. Here, using murine models of lymphoma, we determined that the antitumor effects of PG545 are critically dependent on NK cell activation and that NK cell activation by PG545 requires TLR9. We demonstrate that PG545 does not activate TLR9 directly but instead enhances TLR9 activation through the elevation of the TLR9 ligand CpG in DCs. Specifically, PG545 treatment resulted in CpG accumulation in the lysosomal compartment of DCs, leading to enhanced production of IL-12, which is essential for PG545-mediated NK cell activation. Overall, these results reveal that PG545 activates NK cells and that this activation is critical for the antitumor effect of PG545. Moreover, our findings may have important implications for improving NK cell-based antitumor therapies. PMID:26649979

  11. Antiamnesic properties of analogs and mimetics of the tripeptide human urocortin 3.

    PubMed

    Telegdy, Gyula; Kovács, Anita Kármen; Rákosi, Kinga; Zarándi, Márta; Tóth, Gábor K

    2016-09-01

    Amnesia is a deficit in memory caused by brain damage, disease, or trauma. Until now, there are no successful medications on the drug market available to treat amnesia. Short analogs and mimetics of human urocortin 3 (Ucn 3) tripeptide were synthetized and tested for their action against amnesia induced by eletroconvulsion in mice. Among the 16 investigated derivatives of Ucn 3 tripeptide, eight compounds displayed antiamnesic effect. Our results proved that the configuration of chiral center of glutamine does not affect the antiamnesic properties. Alkyl amide or isoleucyl amide at the C-terminus may lead to antiamnesic compounds. As concerned the N-terminus, acetyl, Boc, and alkyl ureido moieties were found among the active analogs, but the free amino function at the N-terminus usually led to an inactive derivatives. These observations may lead to the design and synthesis of small peptidomimetics and amino acid derivatives as antiamnesic drug candidates, although the elucidation of the mechanism of the action requires further investigations. PMID:27262310

  12. Prussian Blue Nanoparticles as Multienzyme Mimetics and Reactive Oxygen Species Scavengers.

    PubMed

    Zhang, Wei; Hu, Sunling; Yin, Jun-Jie; He, Weiwei; Lu, Wei; Ma, Ming; Gu, Ning; Zhang, Yu

    2016-05-11

    The generation of reactive oxygen species (ROS) is an important mechanism of nanomaterial toxicity. We found that Prussian blue nanoparticles (PBNPs) can effectively scavenge ROS via multienzyme-like activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) activity. Instead of producing hydroxyl radicals (•OH) through the Fenton reaction, PBNPs were shown to be POD mimetics that can inhibit •OH generation. We theorized for the first time that the multienzyme-like activities of PBNPs were likely caused by the abundant redox potentials of their different forms, making them efficient electron transporters. To study the ROS scavenging ability of PBNPs, a series of in vitro ROS-generating models was established using chemicals, UV irradiation, oxidized low-density lipoprotein, high glucose contents, and oxygen glucose deprivation and reperfusion. To demonstrate the ROS scavenging ability of PBNPs, an in vivo inflammation model was established using lipoproteins in Institute for Cancer Research (ICR) mice. The results indicated that PBNPs hold great potential for inhibiting or relieving injury induced by ROS in these pathological processes. PMID:26918394

  13. Defensive Chemistry of Lycid Beetles and of Mimetic Cerambycid Beetles that Feed on Them

    PubMed Central

    Eisner, Thomas; Schroeder, Frank C.; Snyder, Noel; Grant, Jacqualine B.; Aneshansley, Daniel J.; Utterback, David; Meinwald, Jerrold; Eisner, Maria

    2008-01-01

    Summary Beetles of the family Lycidae have long been known to be chemically protected. We present evidence that North American species of the lycid genera Calopteron and Lycus are rejected by thrushes, wolf spiders, and orb-weaving spiders, and that they contain a systemic compound that could account, at least in part, for this unacceptability. This compound, a novel acetylenic acid that we named lycidic acid, proved actively deterrent in feeding tests with wolf spiders and coccinellid beetles. Species of Lycus commonly figure as models of mimetic associations. Among their mimics are species of the cerambycid beetle genus Elytroleptus, remarkable because they prey upon the model lycids. We postulated that by doing so Elytroleptus might incorporate the lycidic acid from their prey for their own defense. However, judging from analytical data, the beetles practice no such sequestration, explaining why they remain relatively palatable (in tests with wolf spiders) even after having fed on lycids. Chemical analyses also showed the lycids to contain pyrazines, such as were already known from other Lycidae, potent odorants that could serve in an aposematic capacity to forestall predatory attacks. PMID:18698369

  14. Simple avarone mimetics as selective agents against multidrug resistant cancer cells.

    PubMed

    Jeremić, Marko; Pešić, Milica; Dinić, Jelena; Banković, Jasna; Novaković, Irena; Šegan, Dejan; Sladić, Dušan

    2016-08-01

    In this work, synthesis of alkylamino and aralkylamino derivatives of sesquiterpene quinone avarone and its model compound tert-butylquinone was described. For all obtained derivatives biological activity was studied. Cytotoxic activity of the synthesized derivatives towards multidrug resistant MDR human non-small cell lung carcinoma NCI-H460/R cells, their sensitive counterpart NCI-H460 and human normal keratinocytes (HaCaT) as well as detection of cell death superoxide anion generation were investigated. Antimicrobial activity towards Gram positive and Gram negative bacteria and fungal cultures was determined. The results showed that strong cytotoxic activity toward cancer cells was improved with simple avarone mimetics. Some derivatives were selective towards MDR cancer cells. The most active derivatives induced apoptosis in both cancer cell lines, but not in normal cells. Superoxide production was induced by 2,6-disubstituted compounds in MDR cancer cells and not by less active 2,5-disubstituted compounds and was accompanied by the collapse of the mitochondrial transmembrane potential. Two tert-butylquinone derivatives were particularly selective towards MDR cancer cells. Some tert-butylquinone derivatives exhibited a strong antimicrobial activity. PMID:27128177

  15. Physics of cell adhesion: some lessons from cell-mimetic systems

    PubMed Central

    Sackmann, Erich; Smith, Ana-Sunčana

    2014-01-01

    Cell adhesion is a paradigm of the ubiquitous interplay of cell signalling, modulation of material properties and biological functions of cells. It is controlled by competition of short range attractive forces, medium range repellant forces and the elastic stresses associated with local and global deformation of the composite cell envelopes. We review the basic physical rules governing the physics of cell adhesion learned by studying cell-mimetic systems and demonstrate the importance of these rules in the context of cellular systems. We review how adhesion induced micro-domains couple to the intracellular actin and microtubule networks allowing cells to generate strong forces with a minimum of attractive cell adhesion molecules (CAMs) and to manipulate other cells through filopodia over micrometer distances. The adhesion strength can be adapted to external force fluctuations within seconds by varying the density of attractive and repellant CAMs through exocytosis and endocytosis or protease-mediated dismantling of the CAM–cytoskeleton link. Adhesion domains form local end global biochemical reaction centres enabling the control of enzymes. Actin–microtubule crosstalk at adhesion foci facilitates the mechanical stabilization of polarized cell shapes. Axon growth in tissue is guided by attractive and repulsive clues controlled by antagonistic signalling pathways. PMID:24651316

  16. Interfacial Cavity Filling To Optimize CD4-Mimetic Miniprotein Interactions with HIV-1 Surface Glycoprotein

    SciTech Connect

    Morellato-Castillo, Laurence; Acharya, Priyamvada; Combes, Olivier; Michiels, Johan; Descours, Anne; Ramos, Oscar H.P.; Yang, Yongping; Vanham, Guido; Ariën, Kevin K.; Kwong, Peter D.; Martin, Loïc; Kessler, Pascal

    2013-08-05

    Ligand affinities can be optimized by interfacial cavity filling. A hollow (Phe43 cavity) between HIV-1 surface glycoprotein (gp120) and cluster of differentiation 4 (CD4) receptor extends beyond residue phenylalanine 43 of CD4 and cannot be fully accessed by natural amino acids. To increase HIV-1 gp120 affinity for a family of CD4-mimetic miniproteins (miniCD4s), we targeted the gp120 Phe43 cavity with 11 non-natural phenylalanine derivatives, introduced into a miniCD4 named M48 (1). The best derivative, named M48U12 (13), bound HIV-1 YU2 gp120 with 8 pM affinity and showed potent HIV-1 neutralization. It contained a methylcyclohexyl derivative of 4-aminophenylalanine, and its cocrystal structure with gp120 revealed the cyclohexane ring buried within the gp120 hydrophobic core but able to assume multiple orientations in the binding pocket, and the aniline nitrogen potentially providing a focus for further improvement. Altogether, the results provide a framework for filling the interfacial Phe43 cavity to enhance miniCD4 affinity.

  17. A mimetic spectral element solver for the Grad-Shafranov equation

    NASA Astrophysics Data System (ADS)

    Palha, A.; Koren, B.; Felici, F.

    2016-07-01

    In this work we present a robust and accurate arbitrary order solver for the fixed-boundary plasma equilibria in toroidally axisymmetric geometries. To achieve this we apply the mimetic spectral element formulation presented in [56] to the solution of the Grad-Shafranov equation. This approach combines a finite volume discretization with the mixed finite element method. In this way the discrete differential operators (∇, ∇×, ∇ṡ) can be represented exactly and metric and all approximation errors are present in the constitutive relations. The result of this formulation is an arbitrary order method even on highly curved meshes. Additionally, the integral of the toroidal current Jϕ is exactly equal to the boundary integral of the poloidal field over the plasma boundary. This property can play an important role in the coupling between equilibrium and transport solvers. The proposed solver is tested on a varied set of plasma cross sections (smooth and with an X-point) and also for a wide range of pressure and toroidal magnetic flux profiles. Equilibria accurate up to machine precision are obtained. Optimal algebraic convergence rates of order p + 1 and geometric convergence rates are shown for Soloviev solutions (including high Shafranov shifts), field-reversed configuration (FRC) solutions and spheromak analytical solutions. The robustness of the method is demonstrated for non-linear test cases, in particular on an equilibrium solution with a pressure pedestal.

  18. Heparan sulfate mimetic PG545-mediated antilymphoma effects require TLR9-dependent NK cell activation

    PubMed Central

    Brennan, Todd V.; Lin, Liwen; Brandstadter, Joshua D.; Rendell, Victoria R.; Dredge, Keith; Huang, Xiaopei; Yang, Yiping

    2015-01-01

    Heparan sulfate (HS) is an essential component of the extracellular matrix (ECM), which serves as a barrier to tumor invasion and metastasis. Heparanase promotes tumor growth by cleaving HS chains of proteoglycan and releasing HS-bound angiogenic growth factors and facilitates tumor invasion and metastasis by degrading the ECM. HS mimetics, such as PG545, have been developed as antitumor agents and are designed to suppress angiogenesis and metastasis by inhibiting heparanase and competing for the HS-binding domain of angiogenic growth factors. However, how PG545 exerts its antitumor effect remains incompletely defined. Here, using murine models of lymphoma, we determined that the antitumor effects of PG545 are critically dependent on NK cell activation and that NK cell activation by PG545 requires TLR9. We demonstrate that PG545 does not activate TLR9 directly but instead enhances TLR9 activation through the elevation of the TLR9 ligand CpG in DCs. Specifically, PG545 treatment resulted in CpG accumulation in the lysosomal compartment of DCs, leading to enhanced production of IL-12, which is essential for PG545-mediated NK cell activation. Overall, these results reveal that PG545 activates NK cells and that this activation is critical for the antitumor effect of PG545. Moreover, our findings may have important implications for improving NK cell–based antitumor therapies. PMID:26649979

  19. Interfacial cavity filling to optimize CD4-mimetic miniprotein interactions with the HIV-1 surface protein

    PubMed Central

    Morellato-Castillo, Laurence; Acharya, Priyamvada; Combes, Olivier; Michiels, Johan; Descours, Anne; Ramos, Oscar H. P.; Yang, Yongping; Vanham, Guido; Ariën, Kevin K.; Kwong, Peter D.; Martin, Loïc; Kessler, Pascal

    2013-01-01

    Ligand affinities can be optimized by interfacial cavity filling. A hollow (Phe43 cavity) between HIV-1 surface protein (gp120) and cluster of differentiation 4 (CD4) receptor, extends beyond residue phenylalanine 43 of CD4 and cannot be fully accessed by natural amino acids. To increase HIV-1 gp120 affinity for a family of CD4-mimetic miniproteins (miniCD4s), we targeted the gp120 Phe43 cavity with eleven non-natural phenylalanine derivatives, introduced into a miniCD4 named M48 (1). The best derivative named M48U12 (13) binds HIV-1 YU2 gp120 with 8 pM affinity, and shows potent HIV-1 neutralization. It contained a methylcyclohexyl derivative of 4-aminophenylalanine and its co-crystal structure with gp120 revealed the cyclohexane ring buried within the gp120 hydrophobic core but able to assume multiple orientations in the binding pocket, and an aniline nitrogen potentially providing a focus for further improvement. Altogether, the results provide a framework for filling the interfacial Phe43 cavity to enhance miniCD4 affinity. PMID:23710622

  20. Endothelial targeting of liposomes encapsulating SOD/catalase mimetic EUK-134 alleviates acute pulmonary inflammation.

    PubMed

    Howard, Melissa D; Greineder, Colin F; Hood, Elizabeth D; Muzykantov, Vladimir R

    2014-03-10

    Production of excessive levels of reactive oxygen species (ROS) in the vascular endothelium is a common pathogenic pathway in many dangerous conditions, including acute lung injury, ischemia-reperfusion, and inflammation. Ineffective delivery of antioxidants to the endothelium limits their utility for management of these conditions. In this study, we devised a novel translational antioxidant intervention targeted to the vascular endothelium using PEG-liposomes loaded with EUK-134 (EUK), a potent superoxide dismutase/catalase mimetic. EUK loaded into antibody-coated liposomes (size 197.8±4.5 nm diameter, PDI 0.179±0.066) exerted partial activity in the intact carrier, while full activity was recovered upon liposome disruption. For targeting we used antibodies (Abs) to platelet-endothelial cell adhesion molecule (PECAM-1). Both streptavidin-biotin and SATA/SMCC conjugation chemistries provided binding of 125-150 Ab molecules per liposome. Ab/EUK/liposomes, but not IgG/EUK/liposomes: i) bound to endothelial cells and inhibited cytokine-induced inflammatory activation in vitro; and, ii) accumulated in lungs after intravascular injection, providing >60% protection against pulmonary edema in endotoxin-challenged mice (vs <6% protection afforded by IgG/liposome/EUK counterpart). Since the design elements of this drug delivery system are already in clinical use (PEG-liposomes, antibodies, SATA/SMCC conjugation), it is an attractive candidate for translational interventions using antioxidant molecules such as EUK and other clinically acceptable drugs. PMID:24412573

  1. Mimetic finite difference method for the stokes problem on polygonal meshes

    SciTech Connect

    Lipnikov, K; Beirao Da Veiga, L; Gyrya, V; Manzini, G

    2009-01-01

    Various approaches to extend the finite element methods to non-traditional elements (pyramids, polyhedra, etc.) have been developed over the last decade. Building of basis functions for such elements is a challenging task and may require extensive geometry analysis. The mimetic finite difference (MFD) method has many similarities with low-order finite element methods. Both methods try to preserve fundamental properties of physical and mathematical models. The essential difference is that the MFD method uses only the surface representation of discrete unknowns to build stiffness and mass matrices. Since no extension inside the mesh element is required, practical implementation of the MFD method is simple for polygonal meshes that may include degenerate and non-convex elements. In this article, we develop a MFD method for the Stokes problem on arbitrary polygonal meshes. The method is constructed for tensor coefficients, which will allow to apply it to the linear elasticity problem. The numerical experiments show the second-order convergence for the velocity variable and the first-order for the pressure.

  2. Biomimetic peptide nanosensors.

    PubMed

    Cui, Yue; Kim, Sang N; Naik, Rajesh R; McAlpine, Michael C

    2012-05-15

    The development of a miniaturized sensing platform tailored for sensitive and selective detection of a variety of biochemical analytes could offer transformative fundamental and technological opportunities. Due to their high surface-to-volume ratios, nanoscale materials are extremely sensitive sensors. Likewise, peptides represent robust substrates for selective recognition due to the potential for broad chemical diversity within their relatively compact size. Here we explore the possibilities of linking peptides to nanosensors for the selective detection of biochemical targets. Such systems raise a number of interesting fundamental challenges: What are the peptide sequences, and how can rational design be used to derive selective binders? What nanomaterials should be used, and what are some strategies for assembling hybrid nanosensors? What role does molecular modeling play in elucidating response mechanisms? What is the resulting performance of these sensors, in terms of sensitivity, selectivity, and response time? What are some potential applications? This Account will highlight our early attempts to address these research challenges. Specifically, we use natural peptide sequences or sequences identified from phage display as capture elements. The sensors are based on a variety of nanomaterials including nanowires, graphene, and carbon nanotubes. We couple peptides to the nanomaterial surfaces via traditional surface functionalization methods or self-assembly. Molecular modeling provides detailed insights into the hybrid nanostructure, as well as the sensor detection mechanisms. The peptide nanosensors can distinguish chemically camouflaged mixtures of vapors and detect chemical warfare agents with sensitivities as low as parts-per-billion levels. Finally, we anticipate future uses of this technology in biomedicine: for example, devices based on these sensors could detect disease from the molecular components in human breath. Overall, these results provide a

  3. Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

    PubMed Central

    Paik, Bradford A.; Blanco, Marco A.; Jia, Xinqiao; Roberts, Christopher J.; Kiick, Kristi L.

    2015-01-01

    Polymer-peptide conjugates were produced via the copper-catalyzed alkyne-azide cycloaddition of poly(tert butyl acrylate) (PtBA) and elastin-like peptides. An azide-functionalized polymer was produced via atom-transfer radical polymerization (ATRP) followed by conversion of bromine end groups to azide groups. Subsequent reaction of the polymer with a bis-alkyne-functionalized, elastin-like peptide proceeded with high efficiency, yielding di- and tri-block conjugates, which after deprotection, yielded poly(acrylic acid) (PAA)-based diblock and triblock copolymers. These conjugates were solubilized in dimethyl formamide, and titration of phosphate buffered saline (PBS) induced aggregation. The presence of polydisperse spherical aggregates was confirmed by dynamic light scattering and transmission electron microscopy. Additionally, a coarse-grained molecular model was designed to reasonably capture inter- and intramolecular interactions for the conjugates and its precursors. This model was used to assess the effect of the different interacting molecular forces on the conformational thermodynamic stability of the copolymers. Our results indicated that the PAA’s ability to hydrogen-bond with both itself and the peptide is the main interaction for stabilizing the diblocks and triblocks and driving their self-assembly, while interactions between peptides are suggested to play only a minor role on the conformational and thermodynamic stability of the conjugates. PMID:25611563

  4. Proline Editing: A General and Practical Approach to the Synthesis of Functionally and Structurally Diverse Peptides. Analysis of Steric versus Stereoelectronic Effects of 4-Substituted Prolines on Conformation within Peptides

    PubMed Central

    Pandey, Anil K.; Naduthambi, Devan; Thomas, Krista M.; Zondlo, Neal J.

    2013-01-01

    Functionalized proline residues have diverse applications. Herein we describe a practical approach, proline editing, for the synthesis of peptides with stereospecifically modified proline residues. Peptides are synthesized by standard solid-phase-peptide-synthesis to incorporate Fmoc-Hydroxyproline (4R-Hyp). In an automated manner, the Hyp hydroxyl is protected and the remainder of the peptide synthesized. After peptide synthesis, the Hyp protecting group is orthogonally removed and Hyp selectively modified to generate substituted proline amino acids, with the peptide main chain functioning to “protect” the proline amino and carboxyl groups. In a model tetrapeptide (Ac-TYPN-NH2), 4R-Hyp was stereospecifically converted to 122 different 4-substituted prolyl amino acids, with 4R or 4S stereochemistry, via Mitsunobu, oxidation, reduction, acylation, and substitution reactions. 4-Substituted prolines synthesized via proline editing include incorporated structured amino acid mimetics (Cys, Asp/Glu, Phe, Lys, Arg, pSer/pThr), recognition motifs (biotin, RGD), electron-withdrawing groups to induce stereoelectronic effects (fluoro, nitrobenzoate), handles for heteronuclear NMR (19F:fluoro; pentafluorophenyl or perfluoro-tert-butyl ether; 4,4-difluoro; 77SePh) and other spectroscopies (fluorescence, IR: cyanophenyl ether), leaving groups (sulfonate, halide, NHS, bromoacetate), and other reactive handles (amine, thiol, thioester, ketone, hydroxylamine, maleimide, acrylate, azide, alkene, alkyne, aryl halide, tetrazine, 1,2-aminothiol). Proline editing provides access to these proline derivatives with no solution phase synthesis. All peptides were analyzed by NMR to identify stereoelectronic and steric effects on conformation. Proline derivatives were synthesized to permit bioorthogonal conjugation reactions, including azide-alkyne, tetrazinetrans-cyclooctene, oxime, reductive amination, native chemical ligation, Suzuki, Sonogashira, cross-metathesis, and Diels

  5. Synergistic killing of human small cell lung cancer cells by the Bcl-2-inositol 1,4,5-trisphosphate receptor disruptor BIRD-2 and the BH3-mimetic ABT-263

    PubMed Central

    Greenberg, E F; McColl, K S; Zhong, F; Wildey, G; Dowlati, A; Distelhorst, C W

    2015-01-01

    Small cell lung cancer (SCLC) has an annual mortality approaching that of breast and prostate cancer. Although sensitive to initial chemotherapy, SCLC rapidly develops resistance, leading to less effective second-line therapies. SCLC cells often overexpress Bcl-2, which protects cells from apoptosis both by sequestering pro-apoptotic family members and by modulating inositol 1,4,5-trisphosphate receptor (IP3R)-mediated calcium signaling. BH3-mimetic agents such as ABT-263 disrupt the former activity but have limited activity in SCLC patients. Here we report for the first time that Bcl-2-IP3 receptor disruptor-2 (BIRD-2), a decoy peptide that binds to the BH4 domain of Bcl-2 and prevents Bcl-2 interaction with IP3Rs, induces cell death in a wide range of SCLC lines, including ABT-263-resistant lines. BIRD-2-induced death of SCLC cells appears to be a form of caspase-independent apoptosis mediated by calpain activation. By targeting different regions of the Bcl-2 protein and different mechanisms of action, BIRD-2 and ABT-263 induce cell death synergistically. Based on these findings, we propose that targeting the Bcl-2–IP3R interaction be pursued as a novel therapeutic strategy for SCLC, either by developing BIRD-2 itself as a therapeutic agent or by developing small-molecule inhibitors that mimic BIRD-2. PMID:26720343

  6. Glucagon-like peptide 1 (GLP-1)-based therapy upregulates LXR-ABCA1/ABCG1 cascade in adipocytes.

    PubMed

    Mostafa, Ahmed M; Hamdy, Nadia M; El-Mesallamy, Hala O; Abdel-Rahman, Sherif Z

    2015-12-25

    A promising treatment for obesity involves the use of therapeutic agents that increase the level of the glucagon-like peptide (GLP-1) which reduces appetite and food intake. Native GLP-1 is rapidly metabolized by the dipeptidyl peptidase-4 (DPP-4) enzyme and, as such, GLP-1 mimetics or DPP-4 inhibitors represent promising treatment approaches. Interestingly, obese patient receiving such medications showed improved lipid profiles and cholesterol homeostasis, however the mechanism(s) involved are not known. Members of the ATP-binding cassette (ABC) transporters, including ABCA1 and ABCG1, play essential roles in reverse cholesterol transport and in high density lipoprotein (HDL) formation. These transporters are under the transcriptional regulation of liver X receptor alpha (LXR-α). We hypothesize that GLP-1 mimetics and/or DPP-4 inhibitors modulate ABCA1/ABCG1 expression in adipocytes through an LXR-α mediated process and thus affecting cholesterol homeostasis. 3T3-L1 adipocytes were treated with the DPP-4 inhibitor vildagliptin (2 nM) or the GLP-1 mimetic exendin-4 (5 nM). Gene and protein expression of ABCA1, ABCG1 and LXR-α were determined and correlated with cholesterol efflux. Expression levels of interleukin-6 (IL-6), leptin and the glucose transporter-4 (GLUT-4) were also determined. Treatment with both medications significantly increased the expression of ABCA1, ABCG1, LXR-α and GLUT-4, decreased IL-6 and leptin, and improved cholesterol efflux from adipocytes (P < 0.05). Our data suggest that GLP-1-based therapy modulate ABCA1/ABCG1 expression in adipocytes potentially through an LXR-α mediated process. PMID:26603933

  7. Multidimensional signatures in antimicrobial peptides

    PubMed Central

    Yount, Nannette Y.; Yeaman, Michael R.

    2004-01-01

    Conventional analyses distinguish between antimicrobial peptides by differences in amino acid sequence. Yet structural paradigms common to broader classes of these molecules have not been established. The current analyses examined the potential conservation of structural themes in antimicrobial peptides from evolutionarily diverse organisms. Using proteomics, an antimicrobial peptide signature was discovered to integrate stereospecific sequence patterns and a hallmark three-dimensional motif. This striking multidimensional signature is conserved among disulfide-containing antimicrobial peptides spanning biological kingdoms, and it transcends motifs previously limited to defined peptide subclasses. Experimental data validating this model enabled the identification of previously unrecognized antimicrobial activity in peptides of known identity. The multidimensional signature model provides a unifying structural theme in broad classes of antimicrobial peptides, will facilitate discovery of antimicrobial peptides as yet unknown, and offers insights into the evolution of molecular determinants in these and related host defense effector molecules. PMID:15118082

  8. Biochemical basis for enhanced binding of peptide dimers to X-linked inhibitor of apoptosis protein.

    PubMed

    Splan, Kathryn E; Allen, John E; McLendon, George L

    2007-10-23

    XIAP (X-linked inhibitor of apoptosis protein) is involved in the mediation of programmed cell death and, therefore, is a target for the development of cancer therapeutics. Peptide mimetics based upon Smac, the natural binding partner of XIAP, and specifically, dimeric peptides, have shown great promise in drug development. In the present work, the basis for enhanced dimer efficacy has been explored. Comparisons are made between the peptide binding site on the BIR3 domain of XIAP alone (residues 238-358) and a less truncated construct that includes both BIR2 and BIR3 domains (residues 151-350). This contingency differentially enhances the binding of dimeric tetrapeptides, potentially by providing additional hydrophobic binding surface. The effect of BIR2 on the BIR3 binding site is sustained, even if the BIR2 binding site is disrupted by mutagenesis, as shown by both a fluorescent competition assay and a polarity sensitive dye, badan. FRET measurements reveal an observed separation of >or=45 A between the BIR2 and BIR3 peptide binding pockets, thereby precluding a direct simultaneous interaction of the dimer molecules with both binding domains. Furthermore, variations in the linker length between dimeric tetrapeptides did not show a predictable trend in binding affinities, suggesting that local concentration effects were also an unlikely explanation for the enhanced dimeric affinities. Taken together, the results suggest that enhanced binding of dimeric peptides likely reflects the increased hydrophobic surface area on or near the BIR3 site and have significant ramifications for the design of therapeutics that target this class of proteins. PMID:17910418

  9. Vaccine for human contraception targeting sperm Izumo protein and YLP12 dodecamer peptide

    PubMed Central

    Naz, Rajesh K

    2014-01-01

    There is an urgent need to develop a better method of contraception which is non-steroidal and reversible to control world population explosion and unintended pregnancies. Contraceptive vaccines (CV), especially targeting sperm-specific proteins, can provide an ideal contraceptive modality. Sperm-specific proteins can induce an immune response in women as well as men, thus can be used for CV development in both sexes. In this article, we will review two sperm-specific proteins, namely Izumo protein and YLP12 dodecamer peptide. Gene-knockout studies indicate that Izumo protein is essential for sperm–egg membrane fusion. Vaccination with Izumo protein or its cDNA causes a significant reduction in fertility of female mice. The antibodies to human Izumo inhibit human sperm penetration assay. Recently, our laboratory found that a significant percentage of infertile women have antibodies to Izumo protein. The second sperm-specific protein is YLP12, a peptide mimetic sequence present on human sperm involved in recognition and binding to the human oocyte zona pellucida. Vaccination with YLP12 or its cDNA causes long-term, reversible contraception, without side effects, in female mice. Infertile, but not fertile, men and women have antibodies to YLP12 peptide. Our laboratory has isolated, cloned, and sequenced cDNA encoding human single chain variable fragment (scFv) antibody from infertile men which reacts with YLP12 peptide. The human YLP12 scFv antibody may provide a novel passive immunocontraceptive, the first of its kind. In conclusion, sperm-specific Izumo protein and YLP12 peptide can provide exciting candidates for antisperm CV development. PMID:24723387

  10. Brain Peptides and Psychopharmacology

    ERIC Educational Resources Information Center

    Arehart-Treichel, Joan

    1976-01-01

    Proteins isolated from the brain and used as drugs can improve and apparently even transfer mental states and behavior. Much of the pioneering work and recent research with humans and animals is reviewed and crucial questions that are being posed about the psychologically active peptides are related. (BT)

  11. Cm-p5: an antifungal hydrophilic peptide derived from the coastal mollusk Cenchritis muricatus (Gastropoda: Littorinidae).

    PubMed

    López-Abarrategui, Carlos; McBeth, Christine; Mandal, Santi M; Sun, Zhenyu J; Heffron, Gregory; Alba-Menéndez, Annia; Migliolo, Ludovico; Reyes-Acosta, Osvaldo; García-Villarino, Mónica; Nolasco, Diego O; Falcão, Rosana; Cherobim, Mariana D; Dias, Simoni C; Brandt, Wolfgang; Wessjohann, Ludger; Starnbach, Michael; Franco, Octavio L; Otero-González, Anselmo J

    2015-08-01

    Antimicrobial peptides form part of the first line of defense against pathogens for many organisms. Current treatments for fungal infections are limited by drug toxicity and pathogen resistance. Cm-p5 (SRSELIVHQRLF), a peptide derived from the marine mollusk Cenchritis muricatus peptide Cm-p1, has a significantly increased fungistatic activity against pathogenic Candida albicans (minimal inhibitory concentration, 10 µg/ml; EC50, 1.146 µg/ml) while exhibiting low toxic effects against a cultured mammalian cell line. Cm-p5 as characterized by circular dichroism and nuclear magnetic resonance revealed an α-helical structure in membrane-mimetic conditions and a tendency to random coil folding in aqueous solutions. Additional studies modeling Cm-p5 binding to a phosphatidylserine bilayer in silico and isothermal titration calorimetry using lipid monophases demonstrated that Cm-p5 has a high affinity for the phospholipids of fungal membranes (phosphatidylserine and phosphatidylethanolamine), only moderate interactions with a mammalian membrane phospholipid, low interaction with ergosterol, and no interaction with chitin. Adhesion of Cm-p5 to living C. albicans cells was confirmed by fluorescence microscopy with FITC-labeled peptide. In a systemic candidiasis model in mice, intraperitoneal administration of Cm-p5 was unable to control the fungal kidney burden, although its low amphiphaticity could be modified to generate new derivatives with improved fungicidal activity and stability. PMID:25921828

  12. Antagonistic peptide technology for functional dissection of CLE peptides revisited

    PubMed Central

    Czyzewicz, Nathan; Wildhagen, Mari; Cattaneo, Pietro; Stahl, Yvonne; Pinto, Karine Gustavo; Aalen, Reidunn B.; Butenko, Melinka A.; Simon, Rüdiger; Hardtke, Christian S.; De Smet, Ive

    2015-01-01

    In the Arabidopsis thaliana genome, over 1000 putative genes encoding small, presumably secreted, signalling peptides can be recognized. However, a major obstacle in identifying the function of genes encoding small signalling peptides is the limited number of available loss-of-function mutants. To overcome this, a promising new tool, antagonistic peptide technology, was recently developed. Here, this antagonistic peptide technology was tested on selected CLE peptides and the related IDA peptide and its usefulness in the context of studies of peptide function discussed. Based on the analyses, it was concluded that the antagonistic peptide approach is not the ultimate means to overcome redundancy or lack of loss-of-function lines. However, information collected using antagonistic peptide approaches (in the broad sense) can be very useful, but these approaches do not work in all cases and require a deep insight on the interaction between the ligand and its receptor to be successful. This, as well as peptide ligand structure considerations, should be taken into account before ordering a wide range of synthetic peptide variants and/or generating transgenic plants. PMID:26136270

  13. Antagonistic peptide technology for functional dissection of CLE peptides revisited.

    PubMed

    Czyzewicz, Nathan; Wildhagen, Mari; Cattaneo, Pietro; Stahl, Yvonne; Pinto, Karine Gustavo; Aalen, Reidunn B; Butenko, Melinka A; Simon, Rüdiger; Hardtke, Christian S; De Smet, Ive

    2015-08-01

    In the Arabidopsis thaliana genome, over 1000 putative genes encoding small, presumably secreted, signalling peptides can be recognized. However, a major obstacle in identifying the function of genes encoding small signalling peptides is the limited number of available loss-of-function mutants. To overcome this, a promising new tool, antagonistic peptide technology, was recently developed. Here, this antagonistic peptide technology was tested on selected CLE peptides and the related IDA peptide and its usefulness in the context of studies of peptide function discussed. Based on the analyses, it was concluded that the antagonistic peptide approach is not the ultimate means to overcome redundancy or lack of loss-of-function lines. However, information collected using antagonistic peptide approaches (in the broad sense) can be very useful, but these approaches do not work in all cases and require a deep insight on the interaction between the ligand and its receptor to be successful. This, as well as peptide ligand structure considerations, should be taken into account before ordering a wide range of synthetic peptide variants and/or generating transgenic plants. PMID:26136270

  14. Biochemical functionalization of peptide nanotubes with phage displayed peptides

    NASA Astrophysics Data System (ADS)

    Swaminathan, Swathi; Cui, Yue

    2016-09-01

    The development of a general approach for the biochemical functionalization of peptide nanotubes (PNTs) could open up existing opportunities in both fundamental studies as well as a variety of applications. PNTs are spontaneously assembled organic nanostructures made from peptides. Phage display has emerged as a powerful approach for identifying selective peptide binding motifs. Here, we demonstrate for the first time the biochemical functionalization of PNTs via peptides identified from a phage display peptide library. The phage-displayed peptides are shown to recognize PNTs. These advances further allow for the development of bifunctional peptides for the capture of bacteria and the self-assembly of silver particles onto PNTs. We anticipate that these results could provide significant opportunities for using PNTs in both fundamental studies and practical applications, including sensors and biosensors nanoelectronics, energy storage devices, drug delivery, and tissue engineering.

  15. Biochemical functionalization of peptide nanotubes with phage displayed peptides.

    PubMed

    Swaminathan, Swathi; Cui, Yue

    2016-09-01

    The development of a general approach for the biochemical functionalization of peptide nanotubes (PNTs) could open up existing opportunities in both fundamental studies as well as a variety of applications. PNTs are spontaneously assembled organic nanostructures made from peptides. Phage display has emerged as a powerful approach for identifying selective peptide binding motifs. Here, we demonstrate for the first time the biochemical functionalization of PNTs via peptides identified from a phage display peptide library. The phage-displayed peptides are shown to recognize PNTs. These advances further allow for the development of bifunctional peptides for the capture of bacteria and the self-assembly of silver particles onto PNTs. We anticipate that these results could provide significant opportunities for using PNTs in both fundamental studies and practical applications, including sensors and biosensors nanoelectronics, energy storage devices, drug delivery, and tissue engineering. PMID:27479451

  16. Antimicrobial peptides: premises and promises.

    PubMed

    Reddy, K V R; Yedery, R D; Aranha, C

    2004-12-01

    Antimicrobial peptides (AMPs) are an important component of the natural defences of most living organisms against invading pathogens. These are relatively small (< 10kDa), cationic and amphipathic peptides of variable length, sequence and structure. During the past two decades several AMPs have been isolated from a wide variety of animals, both vertebrates and invertebrates, and plants as well as from bacteria and fungi. Most of these peptides are obtained from different sources like macrophages, neutrophils, epithelial cells, haemocytes, fat body, reproductive tract, etc. These peptides exhibit broad-spectrum activity against a wide range of microorganisms including Gram-positive and Gram-negative bacteria, protozoa, yeast, fungi and viruses. A few peptides have also been found to be cytotoxic to sperm and tumour cells. AMPs are classified based on the three dimensional structural studies carried out with the help of NMR. The peptides are broadly classified into five major groups namely (a) peptides that form alpha-helical structures, (b) peptides rich in cysteine residues, (c) peptides that form beta-sheet, (d) peptides rich in regular amino acids namely histatin, arginine and proline and (e) peptides composed of rare and modified amino acids. Most of these peptides are believed to act by disrupting the plasma membrane leading to the lysis of the cell. AMPs have been found to be excellent candidates for developing novel antimicrobial agents and a few of these peptides show antimicrobial activity against pathogens causing sexually transmitted infection (STI), including HIV/HSV. Peptides, namely magainin and nisin have been shown to demonstrate contraceptive properties in vitro and in vivo. A few peptides have already entered clinical trials for the treatment of impetigo, diabetic foot ulcers and gastric helicobacter infections. In this review, we discuss the source, structures and mode of action with special reference to therapeutic considerations of various AMPs

  17. Constitutive p53 heightens mitochondrial apoptotic priming and favors cell death induction by BH3 mimetic inhibitors of BCL-xL.

    PubMed

    Le Pen, J; Laurent, M; Sarosiek, K; Vuillier, C; Gautier, F; Montessuit, S; Martinou, J C; Letaï, A; Braun, F; Juin, P P

    2016-01-01

    Proapoptotic molecules directly targeting the BCL-2 family network are promising anticancer therapeutics, but an understanding of the cellular stress signals that render them effective is still elusive. We show here that the tumor suppressor p53, at least in part by transcription independent mechanisms, contributes to cell death induction and full activation of BAX by BH3 mimetic inhibitors of BCL-xL. In addition to mildly facilitating the ability of compounds to derepress BAX from BCL-xL, p53 also provides a death signal downstream of anti-apoptotic proteins inhibition. This death signal cooperates with BH3-induced activation of BAX and it is independent from PUMA, as enhanced p53 can substitute for PUMA to promote BAX activation in response to BH3 mimetics. The acute sensitivity of mitochondrial priming to p53 revealed here is likely to be critical for the clinical use of BH3 mimetics. PMID:26844698

  18. Phage-displayed peptide libraries

    PubMed Central

    Zwick, Michael B; Shen, Juqun; Scott, Jamie K

    2014-01-01

    Over the past year, significant advances have been achieved through the use of phage-displayed peptide libraries. A wide variety of bioactive molecules, including antibodies, receptors and enzymes, have selected high-affinity and/or highly-specific peptide ligands from a number of different types of peptide library. The demonstrated therapeutic potential of some of these peptides, as well as new insights into protein structure and function that peptide ligands have provided, highlight the progress made within this rapidly-expanding field. PMID:9720267

  19. An investigation of the mimetic enzyme activity of two-dimensional Pd-based nanostructures

    NASA Astrophysics Data System (ADS)

    Wei, Jingping; Chen, Xiaolan; Shi, Saige; Mo, Shiguang; Zheng, Nanfeng

    2015-11-01

    In this work, we investigated the mimetic enzyme activity of two-dimensional (2D) Pd-based nanostructures (e.g. Pd nanosheets, Pd@Au and Pd@Pt nanoplates) and found that they possess intrinsic peroxidase-, oxidase- and catalase-like activities. These nanostructures were able to activate hydrogen peroxide or dissolved oxygen for catalyzing the oxidation of organic substrates, and decompose hydrogen peroxide to generate oxygen. More systematic investigations revealed that the peroxidase-like activities of these Pd-based nanomaterials were highly structure- and composition-dependent. Among them, Pd@Pt nanoplates displayed the highest peroxidase-like activity. Based on these findings, Pd-based nanostructures were applied for the colorimetric detection of H2O2 and glucose, and also the electro-catalytic reduction of H2O2. This work offers a promising prospect for the application of 2D noble metal nanostructures in biocatalysis.In this work, we investigated the mimetic enzyme activity of two-dimensional (2D) Pd-based nanostructures (e.g. Pd nanosheets, Pd@Au and Pd@Pt nanoplates) and found that they possess intrinsic peroxidase-, oxidase- and catalase-like activities. These nanostructures were able to activate hydrogen peroxide or dissolved oxygen for catalyzing the oxidation of organic substrates, and decompose hydrogen peroxide to generate oxygen. More systematic investigations revealed that the peroxidase-like activities of these Pd-based nanomaterials were highly structure- and composition-dependent. Among them, Pd@Pt nanoplates displayed the highest peroxidase-like activity. Based on these findings, Pd-based nanostructures were applied for the colorimetric detection of H2O2 and glucose, and also the electro-catalytic reduction of H2O2. This work offers a promising prospect for the application of 2D noble metal nanostructures in biocatalysis. Electronic supplementary information (ESI) available: TEM images, EDX and dispersion stability of Pd-based nanomaterials

  20. Inhibition of PI3K/BMX Cell Survival Pathway Sensitizes to BH3 Mimetics in SCLC.

    PubMed

    Potter, Danielle S; Galvin, Melanie; Brown, Stewart; Lallo, Alice; Hodgkinson, Cassandra L; Blackhall, Fiona; Morrow, Christopher J; Dive, Caroline

    2016-06-01

    Most small cell lung cancer