MP-13, a novel chimeric peptide of morphiceptin and pepcan-9, produces potent antinociception with limited side effects.

Pharmacological investigations have substantiated the potential of bifunctional opioid/cannabinoid agonists in delivering potent analgesia while minimizing adverse reactions. Peptide modulators of cannabinoid receptors, known as pepcans, have been investigated before. In this study, we designed a series of chimeric peptides based on pepcans and morphiceptin (YPFP-NH2). Here, we combined injections of pepcans and morphiceptin to investigate the combination treatment of opioids and cannabis and compared the analgesic effect with chimeric compounds. Subsequently, we employed computational docking to screen the compounds against opioid and cannabinoid receptors, along with an acute pain model, to identify the most promising peptide. Among these peptides, MP-13, a morphiceptin and pepcan-9 (PVNFKLLSH) construct, exhibited superior supraspinal analgesic efficacy in the tail-flick test, with an ED50 value at 1.43 nmol/mouse, outperforming its parent peptides and other chimeric analogs. Additionally, MP-13 displayed potent analgesic activity mediated by mu-opioid receptor (MOR), delta-opioid receptor (DOR), and cannabinoid type 1 (CB1) receptor pathways. Furthermore, MP-13 did not induce psychological dependence and gastrointestinal motility inhibition at the effective analgesic doses, and it maintained non-tolerance-forming antinociception throughout a 7-day treatment regimen, with an unaltered count of microglial cells in the periaqueductal gray region, supporting this observation. Moreover, intracerebroventricular administration of MP-13 demonstrated dose-dependent antinociception in murine models of neuropathic, inflammatory, and visceral pain. Our findings provide promising insights for the development of opioid/cannabinoid peptide agonists, addressing a crucial gap in the field and holding significant potential for future research and development. PERSPECTIVE: This article offers insights into the combination treatment of pepcans with morphiceptin. Among the chimeric peptides, MP-13 exhibited potent analgesic effects in a series of preclinical pain models with a favorable side-effect profile.

Neuritogenic glycosaminoglycan hydrogels promote functional recovery after severe traumatic brain injury.

Objective.Severe traumatic brain injury (sTBI) induced neuronal loss and brain atrophy contribute significantly to long-term disabilities. Brain extracellular matrix (ECM) associated chondroitin sulfate (CS) glycosaminoglycans promote neural stem cell (NSC) maintenance, and CS hydrogel implants have demonstrated the ability to enhance neuroprotection, in preclinical sTBI studies. However, the ability of neuritogenic chimeric peptide (CP) functionalized CS hydrogels in promoting functional recovery, after controlled cortical impact (CCI) and suction ablation (SA) induced sTBI, has not been previously demonstrated. We hypothesized that neuritogenic (CS)CP hydrogels will promote neuritogenesis of human NSCs, and accelerate brain tissue repair and functional recovery in sTBI rats.Approach.We synthesized chondroitin 4-Osulfate (CS-A)CP, and 4,6-O-sulfate (CS-E)CP hydrogels, using strain promoted azide-alkyne cycloaddition (SPAAC), to promote cell adhesion and neuritogenesis of human NSCs,in vitro; and assessed the ability of (CS-A)CP hydrogels in promoting tissue and functional repair, in a novel CCI-SA sTBI model,in vivo. Main results.Results indicated that (CS-E)CP hydrogels significantly enhanced human NSC aggregation and migration via focal adhesion kinase complexes, when compared to NSCs in (CS-A)CP hydrogels,in vitro. In contrast, NSCs encapsulated in (CS-A)CP hydrogels differentiated into neurons bearing longer neurites and showed greater spontaneous activity, when compared to those in (CS-E)CP hydrogels. The intracavitary implantation of (CS-A)CP hydrogels, acutely after CCI-SA-sTBI, prevented neuronal and axonal loss, as determined by immunohistochemical analyses. (CS-A)CP hydrogel implanted animals also demonstrated the significantly accelerated recovery of 'reach-to-grasp' function when compared to sTBI controls, over a period of 5-weeks.Significance.These findings demonstrate the neuritogenic and neuroprotective attributes of (CS)CP 'click' hydrogels, and open new avenues for the development of multifunctional glycomaterials that are functionalized with biorthogonal handles for sTBI repair.

The Interaction of SRL-2 Peptide with LRP-1 Receptor and Identification of Breast Cancer Related Biomarkers: An In-silico Approach.

Background: Breast cancer is a multifaceted disease characterized by genetic and epigenetic changes that lead to uncontrolled cell growth and metastasis. Early detection and treatment are crucial for managing diseases. Objectives: The objective of this study is to investigate the potential of chimeric peptides for drug delivery and to identify biomarkers associated with breast cancer. Recent studies have shown that the low-density lipoprotein receptor-related protein 1 (LRP-1) receptor has a significant impact on the development of breast cancer. In order to facilitate the identification of biomarkers, we have created a chimeric peptide that has been proven to bind successfully to the LRP-1 receptor. Methods: To identify biomarkers, we utilized advanced computational methods to conduct a meta-analysis of microarray data. Specifically, the g:Profiler and eXpression2Kinases (X2K) databases were utilized to identify gene ontologies and transcription factors. We then used the Human Protein Atlas to identify and assess crucial gene expressions. Results: Our results demonstrated that nucleolar and spindle-associated protein 1 (NUSAP1), melatonin receptor 1A (MELT), and cyclin-dependent kinase 1 (CDK1) are three hub genes that play pivotal roles in the pathogenesis of breast cancer. Conclusions: The research findings provide a deeper understanding of the molecular mechanisms involved in developing breast cancer. These findings have significant implications for developing novel therapies and diagnostics for this disease.

Design of chimeric GLP-1A using oligomeric bile acids to utilize transporter-mediated endocytosis for oral delivery.

BACKGROUND: Despite the effectiveness of glucagon-like peptide-1 agonist (GLP-1A) in the treatment of diabetes, its large molecular weight and high hydrophilicity result in poor cellular permeability, thus limiting its oral bioavailability. To address this, we developed a chimeric GLP-1A that targets transporter-mediated endocytosis to enhance cellular permeability to GLP-1A by utilizing the transporters available in the intestine, particularly the apical sodium-dependent bile acid transporter (ASBT). METHODS: In silico molecular docking and molecular dynamics simulations were used to investigate the binding interactions of mono-, bis-, and tetra-deoxycholic acid (DOCA) (monoDOCA, bisDOCA, and tetraDOCA) with ASBT. After synthesizing the chimeric GLP-1A-conjugated oligomeric DOCAs (mD-G1A, bD-G1A, and tD-G1A) using a maleimide reaction, in vitro cellular permeability and insulinotropic effects were assessed. Furthermore, in vivo oral absorption in rats and hypoglycemic effect on diabetic db/db mice model were evaluated. RESULTS: In silico results showed that tetraDOCA had the lowest interaction energy, indicating high binding affinity to ASBT. Insulinotropic effects of GLP-1A-conjugated oligomeric DOCAs were not different from those of GLP-1A-Cys or exenatide. Moreover, bD-G1A and tD-G1A exhibited improved in vitro Caco-2 cellular permeability and showed higher in vivo bioavailability (7.58% and 8.63%) after oral administration. Regarding hypoglycemic effects on db/db mice, tD-G1A (50 µg/kg) lowered the glucose level more than bD-G1A (50 µg/kg) compared with the control (35.5% vs. 26.4%). CONCLUSION: GLP-1A was conjugated with oligomeric DOCAs, and the resulting chimeric compound showed the potential not only for glucagon-like peptide-1 receptor agonist activity but also for oral delivery. These findings suggest that oligomeric DOCAs can be used as effective carriers for oral delivery of GLP-1A, offering a promising solution for enhancing its oral bioavailability and improving diabetes treatment.

Efficient titanium surface modified using bifunctional chimeric peptides to prevent biofilm formation by multiple microorganisms.

It is still a challenge to prevent the formation of bacterial biofilms on the surfaces of oral implants. A chemical peptide with binding and antibacterial properties may be a promising agent if used to modify titanium (Ti) surfaces to inhibit biofilm formation. In this study, peptides were designed by linking the antimicrobial sequence derived from human ß-defensin-3 (hBD-3) to the Ti-binding peptide-1 (TBP-1) sequence by using a triple glycine (G) linker. The antimicrobial activity and biocompatibility characteristics of the chemical-peptide-modified Ti surface were then evaluated and the potential antibacterial mechanism was investigated. This study demonstrated that the chemical-peptide-modified surface exhibited satisfactory bactericidal activities against Streptococcus gordonii, Fusobacterium nucleatum, and Porphyromonas gingivalis. In addition to its potent bacteria-killing efficacy, the surface-immobilised chemical peptide also demonstrated excellent biocompatibility to L929 cells. Moreover, the disruption of the integrity of the bacterial membrane partially revealed the antibacterial mechanism of the peptide. This study demonstrated the potential of chemical-peptide-modified Ti surfaces for preventing the occurrence of peri-implant diseases, thereby providing a promising approach to improving the survival rate of oral implants.

Effects of structural changes on antibacterial activity and cytotoxicity due to proline substitutions in chimeric peptide HnMc.

Owing to the rapidly increasing emergence of multidrug-resistant pathogens, antimicrobial peptides (AMPs) are being explored as next-generation antibiotics. However, AMPs present in nature are highly toxic and exhibit low antibacterial activity. Simple modifications, such as amino acid substitution, can enhance antimicrobial activity and cell selectivity. Herein, we show that HnMc-W, substituted by the Phe1Trp analog of HnMc, a chimeric peptide, resulted in membranolytic antibacterial action and enhanced salt tolerance, whereas HnMc-WP1 with one Ser9Pro substitution resulted in a proline-kink helical structure that increased salt-tolerant antibacterial effects and reduced cytotoxicity. In addition, the HnMc-WP2 peptide, designed with a PXXP motif, had a flexible central hinge in its α-helical structure due to the introduction of two Pro and two Gln (X positions, by deletion of two Gln at positions 16 and 17) residues instead of Ser at position. HnMc-WP2 exhibited excellent antibacterial effects without cytotoxicity in vitro. Moreover, its potent antibacterial activity was demonstrated in a drug-resistant Pseudomonas aeruginosa-infected mouse model in vivo. Our findings provide valuable information for the design of peptides with high antibacterial activity and cell selectivity.

Dual targeting salinomycin-loaded smart nanomicelles for enhanced accumulation and therapeutic outcome in breast cancer.

Salinomycin is a polyether compound that exhibits strong anticancer activity and is known as the cancer stem cell inhibitor that reached clinical testing. The rapid elimination of nanoparticles from the bloodstream by the mononuclear phagocyte system (MPS), the liver, and the spleen, accompanied by protein corona (PC) formation, restricts in vivo delivery of nanoparticles in the tumor microenvironment (TME). The DNA aptamer (TA1) that successfully targets the overexpressed CD44 antigen on the surface of breast cancer cells suffers strongly from PC formation in vivo. Thus, cleverly designed targeted strategies that lead to the accumulation of nanoparticles in the tumor become a top priority in the drug delivery field. In this work, dual redox/pH-sensitive poly (ß-amino ester) copolymeric micelles modified with CSRLSLPGSSSKpalmSSS peptide and TA1 aptamer, as dual targeting ligands, were synthesized and fully characterized by physico-chemical methods. These biologically transformable stealth NPs were altered into the two ligand-capped (SRL-2 and TA1) NPs for synergistic targeting of the 4T1 breast cancer model after exposure to the TME. The PC formation was reduced sharply in Raw 264.7 cells by increasing the CSRLSLPGSSSKpalmSSS peptide concentration in modified micelles. Surprisingly, in vitro and in vivo biodistribution findings showed that dual targeted micelle accumulation in the TME of 4T1 breast cancer model was significantly higher than that of single modified formulation, along with deep penetration 24 h after intraperitoneal injection. Also, an in vivo treatment study showed remarkable tumor growth inhibition in 4T1 tumor-bearing Balb/c mice, compared to different formulations, with a 10% lower therapeutic dose (TD) of SAL that was confirmed by hematoxylin and eosin staining (H&E) and the TUNEL assay. Overall, in this study, we developed smart transformable NPs in which the body's own engineering systems alter their biological identity, which resulted in a reduction in therapeutic dosage along with a lowered off-target effect.

Design and construction of a chimeric peptide, MeICT/IMe-AGAP, from two anti-cancer toxins of Iranian Mesobuthus eupeus scorpion.

Scorpion venom contains various toxin peptides with pharmacological and biological properties. Scorpion toxins specifically interact with membrane ion channels which play key roles in progression of cancer. Therefore, scorpion toxins have received special attention for targeting cancer cells. Two new toxins MeICT and IMe-AGAP, isolated from Iranian yellow scorpion, Mesobuthus eupeus, interact specifically with chloride and sodium channels, respectively. Anti-cancer properties of MeICT and IMe-AGAP have been determined before, in addition they show 81 and 93% similarity with two well-known anti-cancer toxins, CTX and AGAP, respectively. The aim of this study was construction of a fusion peptide MeICT/IMe-AGAP to target different ion channels involved in cancer progression. Design and structure of the fusion peptide were investigated by bioinformatics studies. Two fragments encoding MeICT and IMe-AGAP were fused using overlapping primers by SOEing-PCR. MeICT/IMe-AGAP chimeric fragment was cloned into pET32Rh vector, expressed in Escherichia coli host and analyzed by SDS-PAGE. The in silico studies showed that chimeric peptide with GPSPG linker preserved the three-dimensional structure of both peptides and can be functional. Due to the high expression of chloride and sodium channels in various cancer cells, MeICT/IMe-AGAP fusion peptide can be used as an effective agent to target both channels in cancers, simultaneously.

Chimeric Peptides from Californiconus californicus and Heterodontus francisci with Antigen-Binding Capacity: A Conotoxin Scaffold to Create Non-Natural Antibodies (NoNaBodies).

Research into various proteins capable of blocking metabolic pathways has improved the detection and treatment of multiple pathologies associated with the malfunction and overexpression of different metabolites. However, antigen-binding proteins have limitations. To overcome the disadvantages of the available antigen-binding proteins, the present investigation aims to provide chimeric antigen-binding peptides by binding a complementarity-determining region 3 (CDR3) of variable domains of new antigen receptors (VNARs) with a conotoxin. Six non-natural antibodies (NoNaBodies) were obtained from the complexes of conotoxin cal14.1a with six CDR3s from the VNARs of Heterodontus francisci and two NoNaBodies from the VNARs of other shark species. The peptides cal_P98Y vs. vascular endothelial growth factor 165 (VEGF165), cal_T10 vs. transforming growth factor beta (TGF-ß), and cal_CV043 vs. carcinoembryonic antigen (CEA) showed in-silico and in vitro recognition capacity. Likewise, cal_P98Y and cal_CV043 demonstrated the capacity to neutralize the antigens for which they were designed.

Analgesic tolerance and cross-tolerance to the bifunctional opioid/neuropeptide FF receptors agonist EN-9 and µ-opioid receptor ligands at the supraspinal level in mice.

The chimeric peptide EN-9 was reported as a κ-opioid/neuropeptide FF receptors bifunctional agonist that modulated chronic pain with no tolerance. Many lines of evidence have shown that the effect of the κ-opioid receptor is mediated by not only its specific activation but also downstream events participation, especially interaction with the µ-opioid receptor pathway in antinociception and tolerance on most occasions. The present study investigated the acute and chronic cross-tolerance of EN-9 with µ-opioid receptor agonist EM-2, DAMGO, and morphine after intracerebroventricularly (i.c.v) injection in the mouse tail-flick test. In the acute tolerance test, EN-9 showed symmetrical acute cross-tolerance to DAMGO but no cross-tolerance to EM2. In the chronic tolerance test, EN-9 had no tolerance after eight days of repeated administration. However, EN-9 illustrated complete cross-tolerance to morphine and symmetrical cross-tolerance to EM2. In addition, inhibition of NPFF receptor could induce the tolerance development of EN-9. These findings indicated that supraspinal EN-9-induced antinociception contains additional components, which are mediated by the downstream µ-opioid receptor pathway both in acute and chronic treatment, whereas the subtypes of µ-opioid receptor or NPFF system pathway involved in antinociceptive effects induced by EN-9 are complex. Identifying the receptor mechanism could help design preferable bifunctional opioid compounds.

Forced amyloidogenic cooperativity of structurally incompatible peptide segments: Fibrillization behavior of highly aggregation-prone A-chain fragment of insulin coupled to all-L, and alternating L/D octaglutamates.

Aggregation of proteins into amyloid fibrils is driven by interactions between relatively small amyloidogenic segments. The interplay between aggregation-prone and aggregation-resistant fragments within a single polypeptide chain remains obscure. Here, we examine fibrillization behavior of two chimeric peptides, ACC1-13E8 and ACC1-13E8(L/D), in which the highly amyloidogenic fragment of insulin (ACC1-13) is extended by an octaglutamate segment composed of all-L (E8), or alternating L/D residues (E8(L/D)). As separate entities, ACC1-13 readily forms fibrils with the infrared features of parallel ß-sheet while E8 forms antiparallel ß-sheets with the distinct infrared characteristics. This contrasts with the profoundly aggregation-resistant E8(L/D), although L/D patterns have been hypothesized as compatible with aggregated α-sheets. ACC1-13E8 and ACC1-13E8(L/D) are found to be equally prone to fibrillization at low pH, or in the presence of Ca2+ ions. Fibrillar states of both ACC1-13E8 and ACC1-13E8(L/D) reveal the infrared features of highly ordered parallel ß-sheet without evidence of ß2-aggregates (ACC1-13E8) or α-sheets (ACC1-13E8(L/D)). Hence, the preferred structural pattern of ACC1-13 overrides the tendency of E8 to form antiparallel ß-sheets and enforces the fibrillar order in E8(L/D). We demonstrate how the powerful amyloid stretch determines the overall amyloid structure forcing non-amyloidogenic fragments to participate in its native amyloid pattern.

Design of Antimicrobial Peptides with Cell-Selective Activity and Membrane-Acting Mechanism against Drug-Resistant Bacteria.

Antimicrobial peptides (AMPs) can combat drug-resistant bacteria with their unique membrane-disruptive mechanisms. This study aimed to investigate the antibacterial effects of several membrane-acting peptides with amphipathic structures and positional alterations of two tryptophan residues. The synthetic peptides exhibited potent antibacterial activities in a length-dependent manner against various pathogenic drug-resistant and susceptible bacteria. In particular, the location of tryptophan near the N-terminus of AMPs simultaneously increases their antibacterial activity and toxicity. Furthermore, the growth inhibition mechanisms of these newly designed peptides involve cell penetration and destabilization of the cell membrane. These findings provide new insights into the design of peptides as antimicrobial agents and suggest that these peptides can be used as substitutes for conventional antibiotics.

New strategy for the design, production and pre-purification of chimeric peptide with immunomodulatory activity in Salmosalar.

The intensive salmon farming is associated with massive outbreaks of infections. The use of antibiotics for their prevention and control is related to damage to the environment and human health. Antimicrobial peptides (AMPs) have been proposed as an alternative to the use of antibiotics for their antimicrobial and immunomodulatory activities. However, one of the main challenges for its massive clinical application is the high production cost and the complexity of chemical synthesis. Thus, recombinant DNA technology offers a more sustainable, scalable, and profitable option. In the present study, using an AMPs function prediction methodology, we designed a chimeric peptide consisting of sequences derived from cathelicidin fused with the immunomodulatory peptide derived from flagellin. The designed peptide, CATH-FLA was produced by recombinant expression using an easy pre-purification system. The chimeric peptide was able to induce IL-1ß and IL-8 expression in Salmo salar head kidney leukocytes, and prevented Piscirickettsia salmonis-induced cytotoxicity in SHK-1 cells. These results suggest that pre-purification of a recombinant AMP-based chimeric peptide designed in silico allow obtaining a peptide with immunomodulatory activity in vitro. This could solve the main obstacle of AMPs for massive clinical applications.

Chimeric Peptide-Based Biomolecular Constructs for Versatile Nucleic Acid Biosensing.

Nucleic acid biomarkers hold great potential as key indicators for the diagnosis and monitoring of diseases. Herein we design and implement bifunctional chimeric biomolecules composed of a solid-binding peptide (SBP) domain that specifically adsorbs onto solid sensor surfaces and a peptide nucleic acid (PNA) moiety that facilitates anchoring of antisense oligonucleotide (ASO) probes for the detection of nucleic acid targets. A gold-binding peptide, AuBP1, previously selected by directed evolution to specifically bind to gold, served as the basis for immobilizing nucleic acid probes onto gold substrates. Using surface plasmon resonance (SPR) spectroscopy and quartz crystal microbalance (QCM) analyses, we demonstrate the sequential biomolecular assembly of the heterofunctional solid-binding peptide-antisense oligomer (SBP-ASO) construct onto a sensor surface and the subsequent detection of DNA in an aqueous environment. The effect of steric hindrance on optimal probe assembly is observed, establishing that less packing density results in greater target capture efficacy. In addition, an adsorbed layer of chimeric solid-binding peptide-peptide nucleic acid (SBP-PNA) undergoes viscoelastic changes at the solid-liquid interface upon probe immobilization and DNA target capture, whereby the rigid biofunctional layer becomes more flexible. The dual nature of the chimeric construct is highly amenable to a variety of platforms allowing for both specific recognition and probe immobilization on the sensor surface, while the modular design of the solid-binding peptide-antisense oligonucleotide provides facile functionalization of a wide diversity of solid substrates.

Genomic Structure of Two Kv1.3 Channel Blockers from Scorpion Mesobuthus eupeus and Sea Anemone Stichodactyla haddoni and Construction of their Chimeric Peptide as a Novel Blocker.

Different toxins acting on Kv1.3 channel have been isolated from animal venom. MeuKTX toxin from Mesobuthus eupeus phillipsi scorpion and shtx-k toxin from Stichodactyla haddoni sea anemone have been identified as two effective Kv1.3 channel blockers. In this work, we characterized the genomic organization of both toxins. MeuKTX gene contains one intron and two exons, similar to the most scorpion toxins. There are a few reports of genomic structure of sea anemone toxins acting on Kv channels. The sequence encoding mature peptide of shtx-k was located in an exon separated by an intron from the coding exon of the propeptide and signal region. In order to make a peptide with more affinity for Kv1.3 channel and greater stability, the shtx-k/ MeuKTX chimeric peptide was designed and constructed using splicing by overlap extension-PCR (SOE-PCR) method. MeuKTX, shtx-k, and shtx-k/MeuKTX were cloned and the expression of the soluble proteins in E. coli was determined. Molecular docking studies indicated more inhibitory effect of shtx-k/MeuKTX on Kv1.3 channel compared to shtx-k and MeuKTX toxins. Key amino acids binding channel from both toxins, also involved in interaction of chimeric peptide with channel. Our results showed that the fusion peptide, shtx-k/MeuKTX could be an effective agent to target Kv1.3 channel.

Developing Cytokine Storm-Sensitive Therapeutic Strategy in COVID-19 Using 8P9R Chimeric Peptide and Soluble ACE2.

Currently, the COVID-19 pandemic is an international challenge, largely due to lack of effective therapies. Pharmacotherapy has not yet been able to find a definitive treatment for COVID-19. Since SARS-CoV-2 affects several organs, treatment strategies that target the virus in a wider range are expected to be ultimately more successful. To this end, a two-step treatment strategy has been presented. In the first phase of the disease, when the patient is newly infected with the virus and the cytokine storm has not yet been developed, a chimeric peptide is used to inhibit virus entry into the host cell cytosol (by inhibiting endosomal pH acidification) and viral replication. After the virus entry and decrease of angiotensin converting enzyme 2 (ACE2) level, some people are unable to properly compensate for the ACE2 pathway and progress toward the cytokine storm. In the beginning of the cytokine storm, sACE2 protein is very effective in regulating the immune system toward the anti-inflammatory pathway, including M2 macrophages. Hence, the genes of 8P9R chimeric peptide and sACE2 would be inserted in an episomal vector with a separate promoter for each gene: the chimeric peptide gene promoter is a CMV promoter, while the sACE2 gene promoter is a NF-κB-sensitive promoter. The NF-κB-sensitive promoter induces the expression of sACE2 gene soon after elevation of NF-κB which is the main transcription factor of inflammatory genes. Thus, as the expression of inflammatory cytokines increases, the expression of sACE2 increases simultaneously. In this condition, sACE2 can prevent the cytokine storm by inhibiting the pro-inflammatory pathways. To deliver the designed vector to the target cells, mesenchymal stem cell-derived (MSC-derived) exosome-liposome hybrids are used. Herein, the strategy can be considered as a personalized clinical therapy for COVID-19, that can prevent morbidity and mortality in the future.

Sensitization to Drug Treatment in Precursor B-Cell Acute Lymphoblastic Leukemia Is Not Achieved by Stromal NF-κB Inhibition of Cell Adhesion but by Stromal PKC-Dependent Inhibition of ABC Transporters Activity.

Cell adhesion to stromal support and the associated intracellular signaling are central to drug resistance, therefore blocking both has been effective in increasing drug sensitization in leukemia. The stromal Ser/Thr protein kinase C (PKC) has been found to be important for conferring protection to leukemic cells. We aimed at elucidating the intracellular signals connected to cell adhesion and to stromal PKC. We found that NF-κB and Akt were up-regulated in mesenchymal stem cells (MSC) after binding of B-cell acute lymphoblastic leukemia (B-ALL) cells. Nevertheless, Akt inhibition did not induce B-ALL cell detachment. In spite of a clear activation of the NF-κB signaling pathway after B-ALL cell binding (up-regulation NF-κB1/2, and down-regulation of the IKBε and IKBα inhibitors) and an important reduction in cell adhesion after NF-κB inhibition, sensitization to the drug treatment was not observed. This was opposite to the PKC inhibitors Enzastaurin and HKPS, a novel chimeric peptide inhibitor, that were able to increase sensitization to dexamethasone, methotrexate, and vincristine. PLCγ1, Erk1/2, and CREB appear to be related to PKC signaling and PKC effect on drug sensitization since they were contra-regulated by HKPS when compared to dexamethasone-treated cells. Additionally, PKC inhibition by HKPS, but not by Enzastaurin, in MSC reduced the activity of three ABC transporters in leukemic cells treated with dexamethasone, a new indirect mechanism to increase sensitization to drug treatment in B-ALL cells. Our results show the validity of targeting the functional characteristic acquired and modulated during cell-to-cell interactions occurring in the leukemic niche.

Urea based foldamers.

N,N'-linked oligoureas are a class of enantiopure, sequence-defined peptidomimetic oligomers without amino acids that form well-defined and predictable helical structures akin to the peptide α-helix. Oligourea-based foldamers combine a number of features-such as synthetic accessibility, sequence modularity, and folding fidelity-that bode well for their use in a range of applications from medicinal chemistry to catalysis. Moreover, it was recently recognized that this synthetic helical backbone can be combined with regular peptides to generate helically folded peptide-oligourea hybrids that display additional features in terms of helix mimicry and protein-surface recognition properties. Here we provide detailed protocols for the preparation of requested monomers and for the synthesis and purification of homo-oligoureas and peptide-oligourea hybrids.

Hidden in Plain View: Discovery of Chimeric Diabetogenic CD4 T Cell Neo-Epitopes.

The T cell antigens driving autoimmune Type 1 Diabetes (T1D) have been pursued for more than three decades. When diabetogenic CD4 T cell clones and their relevant MHCII antigen presenting alleles were first identified in rodents and humans, the path to discovering the peptide epitopes within pancreatic beta cell proteins seemed straightforward. However, as experimental results accumulated, definitive data were often absent or controversial. Work within the last decade has helped to clear up some of the controversy by demonstrating that a number of the important MHCII presented epitopes are not encoded in the natural beta cell proteins, but in fact are fusions between peptide fragments derived from the same or different proteins. Recently, the mechanism for generating these MHCII diabetogenic chimeric epitopes has been attributed to a form of reverse proteolysis, called transpeptidation, a process that has been well-documented in the production of MHCI presented epitopes. In this mini-review we summarize these data and their implications for T1D and other autoimmune responses.

Antineoplastic Effects and Mechanisms of a New RGD Chimeric Peptide from Bullfrog Skin on the Proliferation and Apoptosis of B16F10 Cells.

Malignant melanoma, an increasingly common form of skin cancer, poses a significant threat to public health, especially when the disease progresses past skin lesions to the stage of advanced metastasis. In this work, a new anti-tumor peptide, temporin La (T-La), was selected from a cDNA library generated from bullfrog skin. Two new derivative antitumor peptides, T-La (S) and T-La (FS), were designed by bioinformatics analysis and coupled with the RGD small molecule peptide to create chimeric RGD peptides, (RGD-T-La [S] and RGD-T-La [FS]). Preliminary experiments showed that the new antitumor peptides had significant antitumor effects. After coupling to the chimeric RGD peptide, the targeted treatment of mouse melanoma was significantly improved. Our data demonstrate that the 4 peptides tested herein significantly inhibited the proliferation, migration, and invasion of B16F10 cells; with an increase in polypeptide concentration, the proportion of melanoma cells in the G0/G1 phase decreased or increased significantly, respectively, the reactive oxygen species (ROS) content increased significantly, the mitochondrial membrane potential decreased significantly, and the expression of pro-apoptotic Bax, Caspase-3, and Caspase-9 increased, and anti-apoptotic Bcl-2 decreased significantly. Tyr and MITF genes were significantly downregulated. In conclusion, the use of these new anti-tumor peptides, when combined with a chimeric RGD peptide, may increase ROS levels and decrease mitochondrial membrane potential by inhibiting the activity of mitochondria, thus releasing apoptosis-promoting factors in B16F10 cells. The present study describes a new potential strategy for the application of promising peptides in the treatment of various cancers.