Delivery of bioactive molecules into the cell: the Trojan horse approach

In Vitro Transcriptome Analysis of Cobalt Boride Nanoparticles on Human Pulmonary Alveolar Cells

Nanobiotechnology influences many different areas, including the medical, food, energy, clothing, and cosmetics industries. Considering the wide usage of nanomaterials, it is necessary to investigate the toxicity potentials of specific nanosized molecules. Boron-containing nanoparticles (NPs) are attracting much interest from scientists due to their unique physicochemical properties. However, there is limited information concerning the toxicity of boron-containing NPs, including cobalt boride (Co₂B) NPs. Therefore, in this study, Co₂B NPs were characterized using X-ray crystallography (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. Then, we performed 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) release, and neutral red (NR) assays for assessing cell viability against Co₂B NP exposure on cultured human pulmonary alveolar epithelial cells (HPAEpiC). In addition, whole-genome microarray analysis was carried out to reveal the global gene expression differentiation of HPAEpiC cells after Co₂B NP application. The cell viability tests unveiled an IC50 value for Co₂B NPs of 310.353 mg/L. The results of our microarray analysis displayed 719 gene expression differentiations (FC ≥ 2) among the analyzed 40,000 genes. The performed visualization and integrated discovery (DAVID) analysis revealed that there were interactions between various gene pathways and administration of the NPs. Based on gene ontology biological processes analysis, we found that the P53 signaling pathway, cell cycle, and cancer-affecting genes were mostly affected by the Co₂B NPs. In conclusion, we suggested that Co₂B NPs would be a safe and effective nanomolecule for industrial applications, particularly for medical purposes.

New Strategies for Stroke Therapy: Nanoencapsulated Neuroglobin

Stroke is a global health and socio-economic problem. However, no efficient preventive and/or palliative treatments have yet been found. Neuroglobin (Ngb) is an endogen neuroprotective protein, but it only exerts its beneficial action against stroke after increasing its basal levels. Therefore, its systemic administration appears to be an efficient therapy applicable to stroke and other neurodegenerative pathologies. Unfortunately, Ngb cannot cross the blood-brain barrier (BBB), making its direct pharmacological use unfeasible. Thus, the association of Ngb with a drug delivery system (DDS), such as nanoparticles (NPs), appears to be a good strategy for overcoming this handicap. NPs are a type of DDS which efficiently transport Ngb and increase its bioavailability in the infarcted area. Hence, we previously built hyaluronate NPS linked to Ngb (Ngb-NPs) as a therapeutic tool against stroke. This nanoformulation induced an improvement of the cerebral infarct prognosis. However, this innovative therapy is still in development, and a more in-depth study focusing on its long-lasting neuroprotectant and neuroregenerative capabilities is needed. In short, this review aims to update the state-of-the-art of stroke therapies based on Ngb, paying special attention to the use of nanotechnological drug-delivering tools.

Cell-penetrating peptide-mediated delivery of therapeutic peptides/proteins to manage the diseases involving oxidative stress, inflammatory response and apoptosis

OBJECTIVES

Peptides and proteins represent great potential for modulating various cellular processes including oxidative stress, inflammatory response, apoptosis and consequently the treatment of related diseases. However, their therapeutic effects are limited by their inability to cross cellular barriers. Cell-penetrating peptides (CPPs), which can transport cargoes into the cell, could resolve this issue, as would be discussed in this review.

KEY FINDINGS

CPPs have been successfully exploited in vitro and in vivo for peptide/protein delivery to treat a wide range of diseases involving oxidative stress, inflammatory processes and apoptosis. Their in vivo applications are still limited due to some fundamental issues of CPPs, including nonspecificity, proteolytic instability, potential toxicity and immunogenicity.

SUMMARY

Totally, CPPs could potentially help to manage the diseases involving oxidative stress, inflammatory response and apoptosis by delivering peptides/proteins that could selectively reach proper intracellular targets. More studies to overcome related CPP limitations and confirm the efficacy and safety of this strategy are needed before their clinical usage.

Examination of Effective Buccal Absorption of Salmon Calcitonin Using Cell-Penetrating Peptide-Conjugated Liposomal Drug Delivery System

Introduction

The buccal route has been considered an attractive alternative delivery route for injectable formulations. Cell-penetrating peptides (CPPs) are gaining increased attention for their cellular uptake and tissue permeation effects. This study was aimed to evaluate the in vitro and ex vivo permeation-enhancing effect of penetratin-conjugated liposomes for salmon calcitonin (sCT) in TR146 human buccal cells and porcine buccal tissues.

Methods

Penetratin was conjugated to phospholipids through a maleimide-thiol reaction. Liposomes were prepared and sCT was encapsulated using a thin-film hydration method. Physical properties such as particle size, zeta potential, encapsulation efficiency, and morphological images via transmission electron microscopy were obtained. Cellular uptake studies were conducted using flow cytometry (FACS) and confocal laser scanning microscopy (CLSM). A cell permeation study was performed using a Transwell^® assay, and permeation through porcine buccal tissue was evaluated. The amount of sCT permeated was quantified using an ELISA kit and was optically observed using CLSM.

Results

The particle size of penetratin-conjugated liposomes was approximately 123.0 nm, their zeta potential was +29.6 mV, and their calcitonin encapsulation efficiency was 18.0%. In the cellular uptake study using FACS and CLSM, stronger fluorescence was observed in penetratin-conjugated liposomes compared with the solution containing free sCT and control liposomes. Likewise, the amount of sCT permeated from penetratin-conjugated liposomes was higher than that from the free sCT solution and control liposomes by 5.8-fold across TR146 cells and 91.5-fold across porcine buccal tissues.

Conclusion

Penetratin-conjugated liposomes are considered a good drug delivery strategy for sCT via the buccal route.

Membrane Molecular Interactions and Induced Structures of CPPs

Cell penetrating peptides (CPPs) are generally defined as short positively charged peptides, containing 5-30 amino acids. Based on their physicochemical properties, they are classified as three main groups, namely hydrophobic, amphipathic, and hydrophilic. They are capable of interacting with the cell membrane without inducing serious toxicity, and they can carry cargo molecules across the membrane. Cargo molecules could be different therapeutics which makes CPPs valuable in the field of drug delivery into living cells. Nowadays, CPPs are considered as potential parts of therapeutics against several diseases.Despite similarities in their primary structure, the interactions of CPPs with a cell membrane may vary a lot. This is even more complicated when the CPP is bound to the cargo molecule. The mechanism(s) of their cellular uptake and endosomal escape have not been completely resolved. Understanding the mechanism of membrane interaction will help us designing a CPP with enhanced, selective cargo delivery, hopefully resulting in better disease treatments. So far energy independent direct membrane penetration and energy-dependent endocytosis have been suggested as two main mechanisms of cellular entry for CPPs, and both may be applicable for the same CPP-complex, depending on the conditions.In order to understand which mechanism is associated with a particular CPP 's cellular uptake in a particular cell (sometimes including endosomal escape), different biological and biophysical methods and strategies have been applied. In this chapter, we will address several biophysical methods, such as fluorescence spectroscopy, circular dichroism (CD) spectroscopy, dynamic light scattering, and NMR .We also review different membrane model systems which are suitable for the biophysical studies. These include large unilamellar phospholipid vesicles (LUVs ), which are the most commonly used in the lipid-peptide interaction studies. Detergent micelles and mixed micelles (bicelles) are also suitable membrane model systems, particularly in high-resolution NMR studies.

Mitochondrial Targeting Probes, Drug Conjugates, and Gene Therapeutics

Mitochondria represent an important drug target for many phatology, including neurodegeneration, metabolic disease, heart failure, ischemia-reperfusion injury, and cancer. Mitochondrial dysfunctions are caused by mutation in mitochondrial DNA or in nuclear genes encoding mitochondrial proteins. Cell-penetrating peptides (CPPs) have been employed to overcome biological barriers, target this organelle, and therapeuticaly restore mitochondrial functions. Here, we describe recent methods used to deliver oligonucleotides targeting mitochondrial protein by using mitochondrial penetrating peptides. In particular, we highlight recent advances of formulated peptides/oligonucleotides nanocomplexes as a proof-of-principle for pharmaceutical form of peptide-based therapeutics.

Engineered Sumoylation-Deficient Prdx6 Mutant Protein-Loaded Nanoparticles Provide Increased Cellular Defense and Prevent Lens Opacity

Aberrant Sumoylation-mediated protein dysfunction is involved in a variety of oxidative and aging pathologies. We previously reported that Sumoylation-deficient Prdx6K^{(lysine)122/142R(Arginine)} linked to the TAT-transduction domain gained stability and protective efficacy. In the present study, we formulated wild-type TAT-HA-Prdx6^WT and Sumoylation-deficient Prdx6-loaded poly-lactic-co-glycolic acid (PLGA) nanoparticles (NPs) to further enhance stability, protective activities, and sustained delivery. We found that in vitro and subconjuctival delivery of Sumoylation-deficient Prdx6-NPs provided a greater protection of lens epithelial cells (LECs) derived from human and Prdx6^-/--deficient mouse lenses against oxidative stress, and it also delayed the lens opacity in Shumiya cataract rats (SCRs) than TAT-HA-Prdx6^WT-NPs. The encapsulation efficiencies of TAT-HA-Prdx6-NPs were ≈56%-62%. Dynamic light scattering (DLS) and atomic force microscopy (AFM) analyses showed that the NPs were spherical, with a size of 50-250 nm and a negative zeta potential (≈23 mV). TAT-HA-Prdx6 analog-NPs released bioactive TAT-HA-Prdx6 (6%-7%) within 24 h. Sumoylation-deficient TAT-HA-Prdx6-NPs provided 35% more protection by reducing the oxidative load of LECs exposed to H₂O₂ compared to TAT-HA-Prdx6^WT-NPs. A subconjuctival delivery of TAT-HA-Prdx6 analog-NPs demonstrated that released TAT-HA-Prdx6^K122/142R could reduce lens opacity by ≈60% in SCRs. Collectively, our results demonstrate for the first time that the subconjuctival delivery of Sumoylation-deficient Prdx6-NPs is efficiently cytoprotective and provide a proof of concept for potential use to delay cataract and oxidative-related pathobiology in general.

Safety Assessments of Nickel Boride Nanoparticles on the Human Pulmonary Alveolar Cells by Using Cell Viability and Gene Expression Analyses

Nickel boride is generally used in the steel industry as a melting accelerator due to its feature of creating a protective and stable attribute at high temperatures. It is also used to improve the hardenability of the steel with boron addition in the production. Thus, safety studies and biocompatibility analysis of nickel boride should be performed comprehensively to understand the limitations of use in various areas. In the present study, nickel boride nanoparticles (Ni₂B NPs) were synthesized by a single-step method and molecule characterizations were performed via the use of X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analyses. Cytotoxicity properties of Ni₂B NPs were identified on human pulmonary alveolar epithelial cells (HPAEpiC) by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), neutral red (NR), and lactate dehydrogenase (LDH) assays. Illumina human ht-12 v4.0 whole-genome microarray analysis was conducted to investigate NiB₂ NPs effects on gene expression regulations of HPAEpiC cells. The database for annotation, visualization, and integrated discovery (DAVID) analysis was performed to reveal the relationship between Ni₂B NP application and cellular pathway alterations. According to cytotoxicity analysis, the IC₅₀ value for Ni₂B NP application was found as 81.99 mg/L concentration. Microarray analysis of Ni₂B NP application was shown for the first time that 693 gene expression changes (FC ≥ 2) occurred significantly over 40.000 gene probes and Ni₂B NPs were observed to affect microtubule regulation, centrosome organization, and phosphoprotein synthesis.

Quantum dots as a theranostic approach in Alzheimer's disease: a systematic review

Aim: Quantum dots (QDs) are nanoparticles that have an emerging application as theranostic agents in several neurodegenerative diseases. The advantage of QDs as nanomedicine is due to their unique optical properties that provide high sensitivity, stability and selectivity at a nanoscale range. Objective: To offer renewed insight into current QD research and elucidate its promising application in Alzheimer's disease (AD) diagnosis and therapy. Methods: A comprehensive literature search was conducted in PubMed and Google Scholar databases that included the following search terms: 'quantum dots', 'blood-brain barrier', 'cytotoxicity', 'toxicity' and 'Alzheimer's disease'; PRISMA guidelines were adhered to. Results: Thirty-four publications were selected to evaluate the ability of QDs to cross the blood-brain barrier, potential toxicity and current AD diagnostic and therapeutic applications. Conclusion: QD's unique optical properties and versatility to conjugate to various biomolecules, while maintaining a nanoscale size, render them a promising theranostic tool in AD.

In Vivo Follow-Up of Gene Inhibition in Solid Tumors Using Peptide-Based Nanoparticles for siRNA Delivery

Small interfering RNA (siRNA) exhibits a high degree of specificity for targeting selected genes. They are efficient on cells in vitro, but in vivo siRNA therapy remains a challenge for solid tumor treatment as siRNAs display difficulty reaching their intracellular target. The present study was designed to show the in vivo efficiency of a new peptide (WRAP5), able to form peptide-based nanoparticles (PBN) that can deliver siRNA to cancer cells in solid tumors. WRAP5:siRNA nanoparticles targeting firefly luciferase (Fluc) were formulated and assayed on Fluc-expressing U87 glioblastoma cells. The mode of action of WRAP5:siRNA by RNA interference was first confirmed in vitro and then investigated in vivo using a combination of bioluminescent reporter genes. Finally, histological analyses were performed to elucidate the cell specificity of this PBN in the context of brain tumors. In vitro and in vivo results showed efficient knock-down of Fluc expression with no toxicity. WRAP5:siFluc remained in the tumor for at least 10 days in vivo. Messenger RNA (mRNA) analyses indicated a specific decrease in Fluc mRNA without affecting tumor growth. Histological studies identified PBN accumulation in the cytoplasm of tumor cells but also in glial and neuronal cells. Through in vivo molecular imaging, our findings established the proof of concept for specific gene silencing in solid tumors. The evidence generated could be translated into therapy for any specific gene in different types of tumors without cell type specificity but with high molecular specificity.

Efficient LRP1-Mediated Uptake and Low Cytotoxicity of Peptide L57 In Vitro Shows Its Promise as CNS Drug Delivery Vector

Although an abundance of drug candidates exists which are aimed at the remediation of central nervous system (CNS) disorders, the utility of some are severely limited by their inability to cross the blood brain barrier. Potential drug delivery systems such as the Angiopep family of peptides have shown modest potential; however, there is a need for novel drug delivery candidates that incorporate peptidomimetics to enhance the efficiency of transcytosis, specificity, and biocompatibility. Here, we report on the first in vitro cellular uptake and cytotoxicity study of a peptidomimetic, cationic peptide, L57. It binds to cluster 4 of the low-density lipoprotein receptor-related protein 1 (LRP1) receptor which is expressed in numerous cell types, such as brain endothelial cells. We used early-passage-number brain microvascular endothelial cells and astrocytes harvested from rat pup brains that highly express LRP1, to study the uptake of L57 versus Angiopep-7 (A7). Uptake of L57 and A7 showed a concentration-dependent increase, with L57 being taken up to a greater degree than A7 at the same concentration. Additionally, peptide uptake in LRP1-deficient PEA 10 cells had greatly reduced uptake. Furthermore, L57 demonstrated excellent cell viability versus A7, showing promise as a potential drug delivery vector for CNS therapeutics.

Independent Size and Fluorescence Emission Determination of Individual Biological Nanoparticles Reveals that Lipophilic Dye Incorporation Does Not Scale with Particle Size

Advancements in nanoparticle characterization techniques are critical for improving the understanding of how biological nanoparticles (BNPs) contribute to different cellular processes, such as cellular communication, viral infection, as well as various drug-delivery applications. Since BNPs are intrinsically heterogeneous, there is a need for characterization methods that are capable of providing information about multiple parameters simultaneously, preferably at the single-nanoparticle level. In this work, fluorescence microscopy was combined with surface-based two-dimensional flow nanometry, allowing for simultaneous and independent determination of size and fluorescence emission of individual BNPs. In this way, the dependence of the fluorescence emission of the commonly used self-inserting lipophilic dye 3,3'-dioctadecyl-5,5'-di(4-sulfophenyl)oxacarbocyanine (SP-DiO) could successfully be correlated with nanoparticle size for different types of BNPs, including synthetic lipid vesicles, lipid vesicles derived from cellular membrane extracts, and extracellular vesicles derived from human SH-SY5Y cell cultures; all vesicles had a radius, r, of ∼50 nm and similar size distributions. The results demonstrate that the dependence of fluorescence emission of SP-DiO on nanoparticle size varies significantly between the different types of BNPs, with the expected dependence on membrane area, r², being observed for synthetic lipid vesicles, while a significant weaker dependence on size was observed for BNPs with more complex composition. The latter observation is attributed to a size-dependent difference in membrane composition, which may influence either the optical properties of the dye and/or the insertion efficiency, indicating that the fluorescence emission of this type of self-inserting dye may not be reliable for determining size or size distribution of BNPs with complex lipid compositions.

Physicochemical studies on the structural stability of the HIV-1 vaccine candidate recombinant Tat protein

HIV-1 transactivator of transcription protein is one of the most promising AIDS vaccine candidates and plays central roles in the virus life cycle and pathogenesis. Understanding structural properties of vaccine candidate antigens leads to rational design of vaccines which improves their presentation to immune system and facilitates their manufacturing and storage. This study aims to investigate structural properties and stability of one variant of HIV-1 Tat recombinant protein using different spectroscopic, electrophoretic, and microscopic methods. Therefore, after the gene transformation, protein expression was optimized in E. coli cells and the C-terminal His₆-tagged protein was purified using Ni-NTA resin. The structural stability of the pure protein was then investigated under different conditions including pH, Zn²⁺ ions, thermal and chemical stress. Acidic and alkaline pHs affects spectroscopic properties of the vaccine in different ways. The structure unfolding experiment shows relatively poor stability of the zinc-free protein sample compared to the ion-containing one. According to the quenching experiment and also thermal stability study results, the protein has attained more structural compactness in the presence of Zn²⁺. Secondary structure of the protein is mainly disordered and didn't significantly affect under various conditions. Finally, different degrees of oligomerization and aggregation were found under physiological conditions.

Gaussian curvature and the budding kinetics of enveloped viruses

The formation of a membrane-enveloped virus starts with the assembly of a curved layer of capsid proteins lining the interior of the plasma membrane (PM) of the host cell. This layer develops into a spherical shell (capsid) enveloped by a lipid-rich membrane. In many cases, the budding process stalls prior to the release of the virus. Recently, Brownian dynamics simulations of a coarse-grained model system reproduced protracted pausing and stalling, which suggests that the origin of pausing/stalling is to be found in the physics of the budding process. Here, we propose that the pausing/stalling observed in the simulations can be understood as a purely kinetic phenomenon associated with the neck geometry. A geometrical potential energy barrier develops during the budding that must be overcome by capsid proteins diffusing along the membrane prior to incorporation into the capsid. The barrier is generated by a conflict between the positive Gauss curvature of the assembling capsid and the negative Gauss curvature of the neck region. A continuum theory description is proposed and is compared with the Brownian simulations of the budding of enveloped viruses.

Despite intense study, the life-cycle of the HIV-1 virus continues to pose mysteries. One of these is the fact that the assembly of an HIV-1 virus along the plasma membrane (PM) of the host cell—the budding process—stalls prior to release of the virus. Many other important viral pathogens with a surrounding lipid membrane envelope display similar stalling. Combining numerical and analytical methods, we demonstrate that the neck-like shape of the membrane that forms prior to release of the virus creates a barrier that blocks the proteins required for the assembly process from reaching the budding virus. An improved understanding of the physics of the blocking process could enable new strategies to combat enveloped viruses.

Screening and characterization of a novel high-efficiency tumor-homing cell-penetrating peptide from the buffalo cathelicidin family

Targeted delivery of antitumor drugs is especially important for tumor therapy. Cell-penetrating peptides (CPPs) have been shown to be very effective drug carriers for tumor therapy. However, most CPPs lack tumor cell specificity. Here, we identified a highly efficient CPP, CAT, from the newly identified buffalo-derived cathelicidin family, which exhibits a preferential binding capacity for multiple tumor cell lines and delivers carried drug molecules into cells. CAT showed an approximately threefold to sixfold higher translocation efficiency than some reported cell-penetrating antimicrobial peptides, including the well-known classical CPP TAT. Moreover, the delivery efficiency of CAT was greater in a variety of tested tumor cells than in normal cells, especially for the human hepatoma cell line SMMC-7721, for which delivery was 7 times more efficient than the normal human embryonic lung cell line MRC-5, according to fluorescent labeling experiment results. CAT was conjugated to the Momordica charantia-derived type-I ribosome-inactivating protein MAP 30, and the cytotoxicity of the MAP 30-CAT fusion protein in the tumor cell line SMMC-7721 was significantly enhanced compared with that of the unconjugated MAP 30. The IC50 value of MAP 30-CAT was approximately 83 times lower than the IC50 value of the original MAP 30. Interestingly, the IC50 value of MAP 30 alone for MRC-5 was approximately twofold higher than the value for SMMC-7721, showing a small difference. However, when MAP 30 was conjugated to CAT, the difference in IC50 values between the two cell lines was significantly increased by 38-fold. The results of the flow cytometric detection of apoptosis revealed that the increase in cytotoxicity after CAT conjugation was mainly caused by the increased induction of apoptosis by the fusion protein. These results suggest that CAT, as a novel tumor-homing CPP, has great potential in drug delivery applications in vivo and will be beneficial to the development of tumor therapeutics.

Retinoprotective Effects of TAT-Bound Vasoactive Intestinal Peptide and Pituitary Adenylate Cyclase Activating Polypeptide

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) belong to the same peptide family and exert a variety of biological functions. Both PACAP and VIP have protective effects in several tissues. While PACAP is known to be a stronger retinoprotective peptide, VIP has very potent anti-inflammatory effects. The need for a non-invasive therapeutic approach has emerged and PACAP has been shown to be retinoprotective when administered in the form of eye drops as well. The cell penetrating peptide TAT is composed of 11 amino acids and tagging of TAT at the C-terminus of neuropeptides PACAP/VIP can enhance the traversing ability of the peptides through the biological barriers. We hypothesized that TAT-bound PACAP and VIP could be more effective in exerting retinoprotective effects when given in eye drops, by increasing the traversing efficacy and enhancing the activation of the PAC1 receptor. Rats were subjected to bilateral carotid artery occlusion (BCCAO), and retinas were processed for histological analysis 14 days later. The efficiency of the TAT-bound peptides to reach the retina was assessed as well as their cAMP increasing ability. Our present study provides evidence, for the first time, that topically administered PACAP and VIP derivatives (PACAP-TAT and VIP-TAT) attenuate ischemic retinal degeneration via the PAC1 receptor presumably due to a multifactorial protective mechanism.

A Novel Peptide Interfering with proBDNF-Sortilin Interaction Alleviates Chronic Inflammatory Pain

Rationale: Brain-derived neurotrophic factor (BDNF) is a key mediator in the development of chronic pain. Sortilin is known to interact with proBDNF and regulate its activity-dependent secretion in cortical neurons. In a rat model of inflammatory pain with intraplantar injection of complete Freund's adjuvant (CFA), we examined the functional role of proBDNF-sortilin interaction in dorsal root ganglia (DRG).

Methods: Expression and co-localization of BDNF and sortilin were determined by immunofluorescence. ProBDNF-sortilin interaction interface was mapped using co-immunoprecipitation and bimolecular fluorescence complementation assay. The analgesic effect of intrathecal injection of a synthetic peptide interfering with proBDNF-sortilin interaction was measured in the CFA model.

Results: BDNF and sortilin were co-localized and their expression was significantly increased in ipsilateral L4/5 DRG upon hind paw CFA injection. In vivo adeno-associated virus-mediated knockdown of sortilin-1 in L5 DRG alleviated pain-like responses. Mapping by serial deletions in the BDNF prodomain indicated that amino acid residues 71-100 supported the proBDNF-sortilin interaction. A synthetic peptide identical to amino acid residues 89-98 of proBDNF, as compared with scrambled peptide, was found to interfere with proBDNF-sortilin interaction, inhibit activity-dependent release of BDNF in vitro and reduce CFA-induced mechanical allodynia and heat hyperalgesia in vivo. The synthetic peptide also interfered with capsaicin-induced phosphorylation of extracellular signal-regulated kinases in ipsilateral spinal cord of CFA-injected rats.

Conclusions: Sortilin-mediated secretion of BDNF from DRG neurons contributes to CFA-induced inflammatory pain. Interfering with proBDNF-sortilin interaction reduced activity-dependent release of BDNF and might serve as a therapeutic approach for chronic inflammatory pain.

Health hazards of nanoparticles: understanding the toxicity mechanism of nanosized ZnO in cosmetic products

In recent years, nanoparticles are being used extensively in personal healthcare products such as cosmetics, sunscreens, soaps, and shampoos. Particularly, metal oxide nanoparticles are gaining competence as key industrial constituents, progressing toward a remarkable rise in their applications. Zinc oxide and titanium oxide nanoparticles are the most commonly employed metal oxide nanoparticles in sunscreens, ointments, foot care, and over the counter topical products. Dermal exposure to these metal oxides predominantly occurs through explicit use of cosmetic products and airway exposure to nanoparticle dusts is primarily mediated via occupational exposure. There is a compelling need to understand the toxicity effects of nanoparticles which can easily enter the cells and induce oxidative stress. Consequently, these products have become a direct source of pollution in the environment and thereby greatly impact our ecosystem. A complete understanding of the toxicity mechanism of nano-ZnO is intended to resolve whether and to what extent such nanoparticles may pose a threat to the environment and to human beings. In this review article, we have discussed the characteristics of metal oxide nanoparticles and its applications in the cosmetic industry. We have also highlighted about their toxicity effects and their impact on human health.

TAT-Ngn2 Enhances Cognitive Function Recovery and Regulates Caspase-Dependent and Mitochondrial Apoptotic Pathways After Experimental Stroke

Neurogenin-2 (Ngn2) is a basic helix-loop-helix (bHLH) transcription factor that contributes to the identification and specification of neuronal fate during neurogenesis. In our previous study, we found that Ngn2 plays an important role in alleviating neuronal apoptosis, which may be viewed as an attractive candidate target for the treatment of cerebral ischemia. However, novel strategies require an understanding of the function and mechanism of Ngn2 in mature hippocampal neurons after global cerebral ischemic injury. Here, we found that the expression of Ngn2 decreased in the hippocampus after global cerebral ischemic injury in mice and in primary hippocampal neurons after oxygen glucose deprivation (OGD) injury. Then, transactivator of transcription (TAT)-Ngn2, which was constructed by fusing a TAT domain to Ngn2, was effectively transported and incorporated into hippocampal neurons after intraperitoneal (i.p.) injection and enhanced cognitive functional recovery in the acute stage after reperfusion. Furthermore, TAT-Ngn2 alleviated hippocampal neuronal damage and apoptosis, and inhibited the cytochrome C (CytC) leak from the mitochondria to the cytoplasm through regulating the expression levels of brain-derived neurotrophic factor (BDNF), phosphorylation tropomyosin-related kinase B (pTrkB), Bcl-2, Bax and cleaved caspase-3 after reperfusion injury in vivo and in vitro. These findings suggest that the downregulation of Ngn2 expression may have an important role in triggering brain injury after ischemic stroke and that the neuroprotection of TAT-Ngn2 against stroke might involve the modulation of BDNF-TrkB signaling that regulates caspase-dependent and mitochondrial apoptotic pathways, which may be an attractive therapeutic strategy for cerebral ischemic injury.

Retinoprotective Effects of TAT-Bound Vasoactive Intestinal Peptide and Pituitary Adenylate Cyclase Activating Polypeptide

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) belong to the same peptide family and exert a variety of biological functions. Both PACAP and VIP have protective effects in several tissues. While PACAP is known to be a stronger retinoprotective peptide, VIP has very potent anti-inflammatory effects. The need for a non-invasive therapeutic approach has emerged and PACAP has been shown to be retinoprotective when administered in the form of eye drops as well. The cell penetrating peptide TAT is composed of 11 amino acids and tagging of TAT at the C-terminus of neuropeptides PACAP/VIP can enhance the traversing ability of the peptides through the biological barriers. We hypothesized that TAT-bound PACAP and VIP could be more effective in exerting retinoprotective effects when given in eye drops, by increasing the traversing efficacy and enhancing the activation of the PAC1 receptor. Rats were subjected to bilateral carotid artery occlusion (BCCAO), and retinas were processed for histological analysis 14 days later. The efficiency of the TAT-bound peptides to reach the retina was assessed as well as their cAMP increasing ability. Our present study provides evidence, for the first time, that topically administered PACAP and VIP derivatives (PACAP-TAT and VIP-TAT) attenuate ischemic retinal degeneration via the PAC1 receptor presumably due to a multifactorial protective mechanism.

Antisense Phosphorodiamidate Morpholino Oligomers as Novel Antiviral Compounds

Phosphorodiamidate morpholino oligomers (PMO) are short single-stranded DNA analogs that are built upon a backbone of morpholine rings connected by phosphorodiamidate linkages. As uncharged nucleic acid analogs, PMO bind to complementary sequences of target mRNA by Watson–Crick base pairing to block protein translation through steric blockade. PMO interference of viral protein translation operates independently of RNase H. Meanwhile, PMO are resistant to a variety of enzymes present in biologic fluids, a characteristic that makes them highly suitable for in vivo applications. Notably, PMO-based therapy for Duchenne muscular dystrophy (DMD) has been approved by the United States Food and Drug Administration which is now a hallmark for PMO-based antisense therapy. In this review, the development history of PMO, delivery methods for improving cellular uptake of neutrally charged PMO molecules, past studies of PMO antagonism against RNA and DNA viruses, PMO target selection, and remaining questions of PMO antiviral strategies are discussed in detail and new insights are provided.

Tumor-targeting delivery of herb-based drugs with cell-penetrating/tumor-targeting peptide-modified nanocarriers

Cancer has become one of the leading causes of mortality globally. The major challenges of conventional cancer therapy are the failure of most chemotherapeutic agents to accumulate selectively in tumor cells and their severe systemic side effects. In the past three decades, a number of drug delivery approaches have been discovered to overwhelm the obstacles. Among these, nanocarriers have gained much attention for their excellent and efficient drug delivery systems to improve specific tissue/organ/cell targeting. In order to enhance targeting efficiency further and reduce limitations of nanocarriers, nanoparticle surfaces are functionalized with different ligands. Several kinds of ligand-modified nanomedicines have been reported. Cell-penetrating peptides (CPPs) are promising ligands, attracting the attention of researchers due to their efficiency to transport bioactive molecules intracellularly. However, their lack of specificity and in vivo degradation led to the development of newer types of CPP. Currently, activable CPP and tumor-targeting peptide (TTP)-modified nanocarriers have shown dramatically superior cellular specific uptake, cytotoxicity, and tumor growth inhibition. In this review, we discuss recent advances in tumor-targeting strategies using CPPs and their limitations in tumor delivery systems. Special emphasis is given to activable CPPs and TTPs. Finally, we address the application of CPPs and/or TTPs in the delivery of plant-derived chemotherapeutic agents.

Construction and Evaluation of the Tumor-Targeting, Cell-Penetrating Multifunctional Molecular Probe iCREKA

A novel tumor stroma targeting and membrane-penetrating cyclic peptide, named iCREKA, was designed and labeled by fluorescein isothiocyanate (FITC) and positron emitter ¹⁸F to build the tumor-targeting tracers. The FITC-iCREKA was proved to have significantly higher cellular uptake in the glioma U87 cells in the presence of activated MMP-2 than that in absence of activated MMP-2 by cells fluorescence test in vitro. The tumor tissue fluorescence microscope imaging demonstrated that FITC-iCREKA accumulated in the walls of the blood vessels and the surrounding stroma in the glioma tumor at 1 h after intravenous injection. While at 3 h after injection, FITC-iCREKA was found to be uptaken in the tumor cells. However, the control FITC-CREKA can only be found in the tumor stroma, not in the tumor cells, no matter at 1 h or 3 h after injection. The whole-animal fluorescence imaging showed that the glioma tumor could be visualized clearly with high fluorescence signal. The microPET/CT imaging further demonstrated that 18F-iCREKA could target U87MG tumor in vivo from 30 min to 2 h after injection. The present study indicated the iCREKA had the capacity of tumor stroma targeting and the membrane-penetrating. It was potential to be developed as the fluorescent and PET tracers for tumor imaging.

Delivery of Small Interfering RNA. A Review and an Example of Application to a Junction Oncogene

RNA interference strategies using small interfering RNA is one of the most important discoveries in biology in recent years. This technology alongside antisense oligonucleotides is very promising and our group has focused its work on the targeting of junction oncogenes with these molecules. We have taken, as first example, papillary thyroid carcinoma. But there is a great need in delivery methods for these molecules in the treatment of cancers. Indeed, many studies have shown that small interfering RNA and antisense oligonucleotides are made efficient by various innovative delivery methods and, under these conditions, offer a powerful new therapeutic tool in cancer treatment.

Multidisciplinary Perspectives for Alzheimer's and Parkinson's Diseases: Hydrogels for Protein Delivery and Cell-Based Drug Delivery as Therapeutic Strategies

This review presents two intriguing multidisciplinary strategies that might make the difference in the treatment of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. The first proposed strategy is based on the controlled delivery of recombinant proteins known to play a key role in these neurodegenerative disorders that are released in situ by optimized polymer-based systems. The second strategy is the use of engineered cells, encapsulated and delivered in situ by suitable polymer-based systems, that act as drug reservoirs and allow the delivery of selected molecules to be used in the treatment of Alzheimer's and Parkinson's diseases. In both these scenarios, the design and development of optimized polymer-based drug delivery and cell housing systems for central nervous system applications represent a key requirement. Materials science provides suitable hydrogel-based tools to be optimized together with suitably designed recombinant proteins or drug delivering-cells that, once in situ, can provide an effective treatment for these neurodegenerative disorders. In this scenario, only interdisciplinary research that fully integrates biology, biochemistry, medicine and materials science can provide a springboard for the development of suitable therapeutic tools, not only for the treatment of Alzheimer's and Parkinson's diseases but also, prospectively, for a wide range of severe neurodegenerative disorders.

In Vivo Applications of Cell-Penetrating Zinc-Finger Transcription Factors

Artificial transcription factors based on zinc finger, TALE, and CRISPR/Cas9 programmable DNA-binding platforms have been widely used to regulate the expression of specific genes in cultured cells, but their delivery into organs such as the brain represents a critical challenge to apply such tools in live animals. In previous work, we developed a zinc-finger-based artificial transcription factor harboring a cell-penetrating peptide (CPP) that could be injected systemically, cross the blood-brain barrier, and alter expression of a specific gene in the brain of an adult mouse. Importantly, our mode of delivery produced widespread distribution throughout the brain. Here we describe methods for the production and purification of the factor, testing CPP activity in cells, and testing CPP activity in mice.

Identification and characterization of novel enhanced cell penetrating peptides for anti-cancer cargo delivery

Cell penetrating peptides (CPP) are able cross the membrane and to transport cargos, presenting a great potential in drug delivery and diagnosis. In this paper, we have identified novel natural or synthetic CPPs. We have validated their rapid and efficient time and dose-dependent penetration, the absence of toxicity, the intracellular localization and the stability to proteases degradation, one of the main bottlenecks of peptides. Moreover, we have associate a cargo (an interfering peptide blocking the association of the serine/threonine phosphatase PP2A to its inhibitor, the oncogene SET) to the new generated shuttles and showed that they new bi-functional peptides keep the original properties of the shuttle and, in addition, are able to induce apoptosis due to the properties of the cargo. The CPPs identified in this study have promising perspectives for future anti-cancer drug delivery.

Near-infrared remotely triggered drug-release strategies for cancer treatment

Remotely controlled, localized drug delivery is highly desirable for potentially minimizing the systemic toxicity induced by the administration of typically hydrophobic chemotherapy drugs by conventional means. Nanoparticle-based drug delivery systems provide a highly promising approach for localized drug delivery, and are an emerging field of interest in cancer treatment. Here, we demonstrate near-IR light-triggered release of two drug molecules from both DNA-based and protein-based hosts that have been conjugated to near-infrared-absorbing Au nanoshells (SiO2 core, Au shell), each forming a light-responsive drug delivery complex. We show that, depending upon the drug molecule, the type of host molecule, and the laser illumination method (continuous wave or pulsed laser), in vitro light-triggered release can be achieved with both types of nanoparticle-based complexes. Two breast cancer drugs, docetaxel and HER2-targeted lapatinib, were delivered to MDA-MB-231 and SKBR3 (overexpressing HER2) breast cancer cells and compared with release in noncancerous RAW 264.7 macrophage cells. Continuous wave laser-induced release of docetaxel from a nanoshell-based DNA host complex showed increased cell death, which also coincided with nonspecific cell death from photothermal heating. Using a femtosecond pulsed laser, lapatinib release from a nanoshell-based human serum albumin protein host complex resulted in increased cancerous cell death while noncancerous control cells were unaffected. Both methods provide spatially and temporally localized drug-release strategies that can facilitate high local concentrations of chemotherapy drugs deliverable at a specific treatment site over a specific time window, with the potential for greatly minimized side effects.

Tat-MyoD fused proteins, together with C2c12 conditioned medium, are able to induce equine adult mesenchimal stem cells towards the myogenic fate

The Tat protein is able to translocate through the plasma membrane and when it is fused with other peptides may acts as a protein transduction system. This ability appears particularly interesting to induce tissue-specific differentiation when the Tat protein is associated to transcription factors. In the present work, the potential of the complex Tat-MyoD in inducing equine peripheral blood mesenchymal stem cells (PB-MSCs) towards the myogenic fate, was evaluated. Results showed that the internalization process of Tat-MyoD happens only in serum free conditions and that the nuclear localization of the fused complex is observed after 15 hours of incubation. However, the supplement of Tat-MyoD only was not sufficient to induce myogenesis and, therefore, in order to achieve the myogenic differentiation of PB-MSCs, conditioned medium from C2C12 cells was added without direct contact. Real Time PCR and immunofluorescence methods evaluated the establishment of a myogenic program. Our results suggest that TAT- transduction of Tat-MyoD, when supported by conditioned medium, represents a useful methodology to induce myogenic differentiation.

Overexpression of TAT-PTD-diapause hormone fusion protein in tobacco and its effect on the larval development of Helicoverpa armigera (Lepidoptera: Noctuidae)

BACKGROUND

The diapause hormone (DH) has been shown either to induce or to terminate diapause, depending on the insect species. In a previous study we demonstrated that the DH from Clostera anastomosis (caDH) has biological activity in Helicoverpa armigera, which prompted us to examine the potential growth-inhibiting or antiherbivory effects of the TAT-caDH fusion protein when expressed in transgenic plants.

RESULTS

In this study, we produced transgenic tobacco plants expressing either the TAT-caDH protein or a TAT-caDH-eGFP fusion version that allowed tracking of the fluorescent protein in plant tissues. Our results indicate that H. armigera larvae feeding on transgenic tobacco expressing TAT-caDH exhibited a significantly reduced survival rate and weight gain. However, larvae feeding on transgenic tobacco expressing TAT-caDH-eGFP were unaffected. While fusion of the eGFP gene influenced the bioactivity of caDH in larvae, TAT-caDH-eGFP can still penetrate the insect midgut cell membrane.

CONCLUSION

TAT-caDH increases DH stability in oral delivery. Our results may help in targeting DH-dependent physiological processes in insects for improving herbivore tolerance in economically important crops. © 2016 Society of Chemical Industry.

A retro-inverso cell-penetrating peptide for siRNA delivery

Background

Small interfering RNAs (siRNAs) are powerful tools to control gene expression. However, due to their poor cellular permeability and stability, their therapeutic development requires a specific delivery system. Among them, cell-penetrating peptides (CPP) have been shown to transfer efficiently siRNA inside the cells. Recently we developed amphipathic peptides able to self-assemble with siRNAs as peptide-based nanoparticles and to transfect them into cells. However, despite the great potential of these drug delivery systems, most of them display a low resistance to proteases.

Results

Here, we report the development and characterization of a new CPP named RICK corresponding to the retro-inverso form of the CADY-K peptide. We show that RICK conserves the main biophysical features of its L-parental homologue and keeps the ability to associate with siRNA in stable peptide-based nanoparticles. Moreover the RICK:siRNA self-assembly prevents siRNA degradation and induces inhibition of gene expression.

Conclusions

This new approach consists in a promising strategy for future in vivo application, especially for targeted anticancer treatment (e.g. knock-down of cell cycle proteins).Graphical abstract

A dual-mediated liposomal drug delivery system targeting the brain: rational construction, integrity evaluation across the blood-brain barrier, and the transporting mechanism to glioma cells

As the global population ages, cancer rates increase worldwide, and degenerative diseases of the central nervous system (CNS), brain tumors, and inflammation threaten human health more frequently. We designed a dual-mediated (receptor-mediated and adsorption-mediated) liposome, named transferrin–cell penetrating peptide–sterically stabilized liposome (TF-CPP-SSL), to improve therapy for gliomas through combining molecular recognition of transferrin receptors (TF-Rs) on the blood–brain barrier (BBB) and glioma cells with the internalization and lysosomal escaping ability of CPP. Based on the systematic investigation of structure–activity relations on the cellular level, we constructed TF-CPP-SSL rationally by conjugating TF and CPP moieties to the liposomes via PEG_3.4K and PEG_2.0K, respectively, and found the optimum densities of TF and CPP were 1.8% and 4%, respectively. These liposomes had the highest targeting efficacy for brain microvascular endothelial cell and C6 cell uptake but avoided capture by normal cells. Fluorescence resonance energy transfer technology and coculture models of BBB and glioma C6 cells indicated that TF-CPP-SSL was transported across the BBB without drug leakage, liposome breakup, or cleavage of ligand. TF-CPP-SSL offered advantages for crossing the BBB and entering into glioma C6 cells. Real-time confocal viewing revealed that TF-CPP-SSL was entrapped in endosomes of glioma C6 cells and then escaped from lysosomes successfully to release the liposomal contents into the cytosol. Entrapped contents, such as doxorubicin, could then enter the nucleus to exert pharmacological effects.

Peptide-based strategies for enhanced cell uptake, transcellular transport, and circulation: Mechanisms and challenges

Peptides are emerging as a new tool in drug and gene delivery. Peptide-drug conjugates and peptide-modified drug delivery systems provide new opportunities to avoid macrophage recognition and subsequent phagocytosis, cross endothelial and epithelial barriers, and enter the cytoplasm of target cells. Peptides are relatively small, low-cost, and are stable in a wide range of biological conditions. In this review, we summarize recent work in designing peptides to enhance penetration of biological barriers, increase cell uptake, and avoid the immune system. We highlight recent successes and contradictory results, and outline common emerging concepts and design rules. The development of sequence-structure-function relationships and standard protocols for benchmarking will be a key to progress in the field.

Transgenic Tobacco Expressing the TAT-Helicokinin I-CpTI Fusion Protein Show Increased Resistance and Toxicity to Helicoverpa armigera (Lepidoptera: Noctuidae)

Insect kinins were shown to have diuretic activity, inhibit weight gain, and have antifeedant activity in insects. In order to study the potential of the TAT-fusion approach to deliver diuretic peptides per os to pest insects, the HezK I peptide from Helicoverpa zea, as a representative of the kinin family, was selected. The fusion gene TAT-HezK I was designed and was used to transform tobacco plants. As a means to further improve the stability of TAT-HezK I, a fusion protein incorporating HezK I, transactivator of transcription (TAT), and the cowpea trypsin inhibitor (CpTI) was also designed. Finally, the toxicity of the different tobacco transgenic strains toward Helicoverpa armigera was compared. The results demonstrated that TAT-HezK I had high toxicity against insects via transgenic expression of the peptide in planta and intake through larval feeding. The toxicity of the fusion TAT-HezK I and CpTI was higher than the CpTI single gene in transgenic tobacco, and the fusion TAT-HezK I and CpTI further enhanced the stability and bioavailability of agents in oral administration. Our research helps in targeting new genes for improving herbivore tolerance in transgenic plant breeding.

Multi-targeting peptides for gene carriers with high transfection efficiency

Non-viral gene carriers for gene therapy have been developed for many years.

Poly(lactic acid) for delivery of bioactive macromolecules

Therapeutic biomolecules often require frequent administration and supramolecular dosing to achieve therapeutic efficiencies and direct infusion into treatment or defect sites results in inadequate physiological response and at times severe side effects or mis-targeting. Delivery systems serve several purposes such as increased circulatory time, increased biomolecule half-life, and incorporation of new innovations can enable highly specific cell targeting and improved cell and nucleus permeability. Poly(lactic acid) (PLA) has become a "material of choice" due to wide availability, reproducible synthetic route, customization, versatility, biodegradability and biocompatibility. Furthermore, PLA is amenable to a variety of fabrication methodologies and chemistries allowing an expansive library correlating physio-chemical properties, characteristics, and applications. This article discusses challenges to biomolecule delivery, and classical approaches of PLA based biomolecule delivery and targeting strategies under development and in trials.

CPP-Assisted Intracellular Drug Delivery, What Is Next?

For the past 20 years, we have witnessed an unprecedented and, indeed, rather miraculous event of how cell-penetrating peptides (CPPs), the naturally originated penetrating enhancers, help overcome the membrane barrier that has hindered the access of bio-macromolecular compounds such as genes and proteins into cells, thereby denying their clinical potential to become potent anti-cancer drugs. By taking the advantage of the unique cell-translocation property of these short peptides, various payloads of proteins, nucleic acids, or even nanoparticle-based carriers were delivered into all cell types with unparalleled efficiency. However, non-specific CPP-mediated cell penetration into normal tissues can lead to widespread organ distribution of the payloads, thereby reducing the therapeutic efficacy of the drug and at the same time increasing the drug-induced toxic effects. In view of these challenges, we present herein a review of the new designs of CPP-linked vehicles and strategies to achieve highly effective yet less toxic chemotherapy in combating tumor oncology.

Sam68/KHDRBS1 is critical for colon tumorigenesis by regulating genotoxic stress-induced NF-κB activation

Nuclear factor kappa B (NF-κB)-mediated transcription is an important mediator for cellular responses to DNA damage. Genotoxic agents trigger a 'nuclear-to-cytoplasmic' NF-κB activation signaling pathway; however, the early nuclear signaling cascade linking DNA damage and NF-κB activation is poorly understood. Here we report that Src-associated-substrate-during-mitosis-of-68kDa/KH domain containing, RNA binding, signal transduction associated 1 (Sam68/KHDRBS1) is a key NF-κB regulator in genotoxic stress-initiated signaling pathway. Sam68 deficiency abolishes DNA damage-stimulated polymers of ADP-ribose (PAR) production and the PAR-dependent NF-κB transactivation of anti-apoptotic genes. Sam68 deleted cells are hypersensitive to genotoxicity caused by DNA damaging agents. Upregulated Sam68 coincides with elevated PAR production and NF-κB-mediated anti-apoptotic transcription in human and mouse colon cancer. Knockdown of Sam68 sensitizes human colon cancer cells to genotoxic stress-induced apoptosis and genetic deletion of Sam68 dampens colon tumor burden in mice. Together our data reveal a novel function of Sam68 in the genotoxic stress-initiated nuclear signaling, which is crucial for colon tumorigenesis.

DOI:http://dx.doi.org/10.7554/eLife.15018.001

Cells use signaling pathways to detect and respond to harmful conditions by switching on genes that keep the cell healthy. One important pathway is the nuclear factor kappa B (NF-κB) signaling pathway, which is activated by many stimuli. These stimuli may come from infections from outside the cell or may originate inside the cell, as seen for DNA damage caused by irradiation, chemicals or rapid DNA replication in cancer cells.

Most of a cell’s DNA is located in the cell nucleus. However, NF-κB proteins are normally located outside the nucleus, in the cell’s cytoplasm. Damage to DNA triggers a signal from the nucleus to the cytoplasm. This signal activates the NF-κB proteins, which move into the nucleus and turn on genes that help the cell to recover from the damage. These genes include those that prevent the cell from self-destructing. In one step of the NF-κB activation process, chain-like molecules called polymers are made from a compound called poly(ADP-ribose), or PAR for short. However, few other details are known about how the damaged DNA in the nucleus signals to the cytoplasm.

A protein called Sam68, which is found in the cell nucleus, has been linked to DNA damage signaling. Fu, Sun et al. now present evidence that suggests that if mouse cells lack Sam68, they do not produce PAR polymers in response to DNA damage. In addition, these cells could not trigger the PAR-dependent signaling cascade that is essential for activating NF-κB and for turning on the protective genes. Consequently, cells that lacked Sam68 were extremely sensitive to agents that cause DNA damage, such as chemicals and irradiation.

The NF-κB pathway is regulated incorrectly in some cancers, but is also activated by DNA damage caused by cancer treatments. Therefore, Fu, Sun et al. also explored the role of Sam68 in cancer. Reducing the levels of Sam68 made human colon cancer cells more likely to self-destruct when they were exposed to DNA-damaging agents. Furthermore, removing Sam68 from mice that spontaneously grow colon cancer caused their tumors to develop more slowly than mice that retained Sam68 in their cells.

Overall, the findings presented by Fu, Sun et al. suggest that Sam68 regulates the signal from the nucleus to the cytoplasm that activates NF-κB proteins in response to DNA damage. Sam68 also appears to be important for helping colon cancer cells grow and survive. Future challenges will be to understand how Sam68 regulates the production of the PAR polymer in this response and to explore whether Sam68 can be targeted for treating cancer.

DOI:http://dx.doi.org/10.7554/eLife.15018.002

Recombinant human Tat-Hsp70-2: A tool for neuroprotection

Human Hsp70-2 is a chaperone expressed mainly in the nervous system. Up to now, no study has reported on the recombinant expression of this important human chaperone. Herein, we describe the successful purification and characterization of recombinant human Hsp70-2 in Escherichia coli in both the full-length and the chimeric protein containing the protein transduction domain corresponding to the trans-activator of transcription (Tat) from HIV. Under optimized conditions, the Tat-Hsp70-2 was expressed in a soluble form and purified by two chromatographic steps (in a 3.6 mg/L fermentation broth yield): recombinant Tat-Hsp70-2 was folded and showed ATPase activity. In contrast, the full-length recombinant protein was only expressed in the form of inclusion bodies and thus was purified following a refolding procedure. The refolded Hsp70-2 protein was inactive and the protein conformation slightly altered as compared to the corresponding Tat-fused variant. The Tat-Hsp70-2 protein (100 nM), when added to human neuroblastoma SH-SY5Y cells subjected to hydrogen peroxide or 6-hydroxydopamine stress, partially protected from the deleterious effect of these treatments. This work describes an approach for the functional expression of human Tat-Hsp70-2 that provides sufficient material for detailed structure-function studies and for testing its ability to protect neuroblastoma cells from oxidative stress.

Protection and immunological study on two tetraspanin-derived vaccine candidates against schistosomiasis japonicum

Tetraspanins (TSPs) are proteins found on the surface of helminth parasites of the genus Schistosoma and are regarded as potentially protective antigens. The large extracellular loop of Schistosoma mansoni tetraspanin-2, Sm-TSP-2, when fused to a thioredoxin partner and formulated with Freund's adjuvants, has been shown to be an efficacious vaccine against murine schistosomiasis. It is well recognized that CD4(+) T-cell-dependent immunity might play an important role against schistosomes; however, the contribution of CD8(+) T cells against multicellular pathogen is still uncertain. The exogenous protein-pulsed dendritic cells (DCs) can easily activate CD4(+) T cells response, while CD8(+) T cells response was relatively difficult to be induced. In this study, we evaluated the immunogenicity of TSP2HD antigen (hydrophilic domain of the S. japonicum tetraspanin-2) and TAT (the protein transduction domain of HIV-1)-coupled TSP2HD protein. As TAT-fused protein could promote major histocompatibility complex class I-dependent antigen presentation in vitro, TAT-TSP2HD-pulsed DCs induced stronger proliferation of schistosome-specific CD8(+) T cells compared with DCs incubated with TSP2HD alone. Vaccination with TAT-TSP2HD-pulsed DCs in vivo could improve disease outcome in S. japonicum-infected mice and was slightly superior to vaccination with DCs treated with TSP2HD. In summary, these data showed that TAT fusion proteins could help activate CD8(+) cells and Th1 cells and provide part protection against schistosome.

Optimisation of vectorisation property: A comparative study for a secondary amphipathic peptide

RNA interference provides a powerful technology for specific gene silencing. Therapeutic applications of small interfering RNA (siRNA) however require efficient vehicles for stable complexation and intracellular delivery. In order to enhance their cell delivery, short amphipathic peptides called cell-penetrating peptides (CPPs) have been intensively developed for the last two decades. In this context, the secondary amphipathic peptide CADY has shown to form stable siRNA complexes and to improve their cellular uptake independent of the endosomal pathway. In the present work, we have described the parameters influencing CADY nanoparticle formation (buffers, excipients, presence of serum, etc.), and have followed in details the CPP:siRNA self-assembly. Once optimal conditions were determined, we have compared the ability of seven different CADY analogues to form siRNA-loaded nanoparticles compared to CADY:siRNA. First of all, we were able to show by biophysical methods that structural polymorphism (α-helix) is an important prerequisite for stable nanoparticle formation independently of occurring sequence mutations. Luciferase assays revealed that siRNA complexed to CADY-K (shorter version) shows better knock-down efficiency on Neuro2a-Luc(+) and B16-F10-Luc(+) cells compared to CADY:siRNA. Altogether, CADY-K is an ideal candidate for further application especially with regards to ex vivo or in vivo applications.

The Late Endosome and Its Lipid BMP Act as Gateways for Efficient Cytosolic Access of the Delivery Agent dfTAT and Its Macromolecular Cargos

Endosomal entrapment is a severely limiting bottleneck in the delivery of biologics into cells. The compound dfTAT was recently found to circumvent this problem by mediating endosomal leakage efficiently and without toxicity. Herein, we report on the mechanism of endosomal escape of this cell-penetrating peptide. By modulating the trafficking of the peptide within the endocytic pathway, we identify late endosomes as the organelles rendered leaky by dfTAT. We establish that dfTAT binds bis(monoacylglycero)phosphate (BMP), a lipid found in late endosomes, and that the peptide causes the fusion and leakage of bilayers containing BMP. Together, these data identify late endosomes as desirable gateways for cell penetration and BMP as a cellular factor that can be exploited for the development of future delivery agents.

Protein transduction domain can enhance the humoral immunity and cross-protection of HPV16L2 peptide vaccines

Due to type-specificity, commercially available human papillomavirus (HPV) vaccines are only effective against homologous HPV serotypes, providing limited protection. Recent studies have highlighted the role of HPV minor capsid protein (known as L2) in inducing cross-protection. The N-terminal peptides of L2 contain conserved cross-response epitopes that can induce neutralizing antibodies against heterogeneous HPVs. However, when compared with L1, these peptides have lower immunogenicity, which limits the application of these vaccines. The protein transduction domain (PTD), located in the Tat protein of human immunodeficiency virus, facilitates delivery of DNA, peptides, proteins and virus particles into cells by unknown mechanisms, and has been reported to enhance immunogenicity of several antigens. In the present study, two peptides derived from the N-terminal of HPV16L2 were chosen as model antigens and constructed a series of L2 peptide vaccines by either fusing or mixing with PTD. Subsequently their immunogenicity was evaluated. The results indicated that the L2 peptides fused with PTD show considerably enhanced humoral immunity. In particular, they increased the titer of cross-neutralizing antibodies, while L2 peptides that had only been mixed with PTD induced only small cross-protection responses. Overall, the data suggest that fusion of L2 peptides with PTD significantly enhances their cross-protection and may be a promising strategy for the development of broad-spectrum HPV prophylactic vaccines.