Cationic Amphiphilic Peptides Research Articles

Evaluation of the Antibacterial Potential of Two Short Linear Peptides YI12 and FK13 against Multidrug-Resistant Bacteria.

The accelerating spread of antibiotic resistance has significantly weakened the clinical efficacy of existing antibiotics, posing a severe threat to public health. There is an urgent need to develop novel antimicrobial alternatives that can bypass the mechanisms of antibiotic resistance and effectively kill multidrug-resistant (MDR) pathogens. Antimicrobial peptides (AMPs) are one of the most promising candidates to treat MDR pathogenic infections since they display broad-spectrum antimicrobial activities and are less prone to achieve drug resistance. In this study, we investigated the antibacterial capability and mechanisms of two machine learning-driven linear peptide compounds termed YI12 and FK13. We reveal that YI12 and FK13 exhibit broad-spectrum antibacterial properties against clinically significant bacterial pathogens, inducing no or minimal hemolysis in mammalian red blood cells. We further ascertain that YI12 and FK13 are resilient to heat and acid-base conditions, and exhibit susceptibility to hydrolytic enzymes and divalent cations under physiological conditions. Initial mechanistic investigations reveal that YI12 and FK13 compromise bacterial membrane integrity, leading to membrane potential dissipation and excessive reactive oxygen species (ROS) generation. Collectively, our findings highlight the prospective utility of these two cationic amphiphilic peptides as broad-spectrum antibacterial agents.

Synthesis of plyphenol-containing cationic linear and dendrimeric peptides with anti-oxidant activity

Natural polyphenols are of great interest from the point of view of their use for the pharmacological control of oxidative stress and many diseases. However, the low bioavailability and rapid metabolism of polyphenols in the form of glycosides or aglycones stimulates the search for effective means of delivery into systemic circulation. Conjugation of polyphenols with cationic amphiphilic peptides can result in compounds with strong antioxidant activity and the ability to cross biological barriers. Such compounds may be in demand as drugs for antioxidant therapy, including for the treatment of viral, oncological and neurodegenerative diseases due to the diverse range of biological activities inherent in polyphenols and peptides. In this work, cationic linear and dendrimer amphiphilic cationic peptides were synthesized by the solid phase method, and a number of peptides were conjugated to gallic acid (Ga). Ga is a non-toxic natural phenolic acid and an important functional element of many flavonoids with high antioxidant activity. It was shown that the resulting Ga-peptide conjugates exhibited antioxidant (antiradical) activity that was 2-3 times higher than that of ascorbic acid. Other tests indicated that the addition of Ga did not affect the toxicity and hemolytic activity of the conjugates. Ga-modified peptides stimulated the transmembrane transfer of the pGL3 plasmid encoding the luciferase reporter gene; however, the addition of Ga to the N-terminus of the peptide reduced its transfection activity. Some of the resulting compounds had noticeable inhibitory activity against theE. сoli-Dh5α strain.

Facile fabrication of anticancer peptide coated zeolite imidazole framework for effective treatment of colorectal cancer cells and its apoptosis induction

The low drug resistance, excellent cancer cell targeting, and anticancer benefits of anticancer peptides (ACPs) make them an attractive antitumor drug option. On the other hand, enzymes readily break down in many ACPs after delivery due to their non-specific toxicity. Consequently, drug delivery systems (DDSs) are necessary to avoid the peptides' dissociation and persuade targeted delivery. The cationic amphiphilic anticancer peptide, G(IIKK)3I-NH2 (G3), was developed in this work using a high-performance microfluidic system, which encapsulates the zeolitic imidazolate framework (ZIF-8). The ACPs-loaded nanoparticles (NPs) were efficiently and quickly mixed using the microfluidic system, resulting in NPs with tunable properties. The encapsulation efficacy was high, and the production rate was 120 mL/min. The microfluidic technique-based ZIF-8 fabrication demonstrated better size homogeneity, as evidenced by a decreased polydispersity index (PDI) compared to the conventional technique. The hemolytic effect was much diminished, and a pH-controlled release of the G3 peptides was achieved by encapsulating G(IIKK)3I-NH2 (termed as G3@ZIF-8) into the ZIF-8. Owing to the improved cell absorption by the ZIF-8, G3@ZIF-8 demonstrated a stronger anticancer impact than the free G3 peptide at identical concentrations. In addition to damaging the mitochondrial membrane of HCT 116 colorectal cancer cells, the NPs were able to suppress the proliferation. Consequently, ACP-based cancer therapy can be expanded by developing G3-loaded ZIF-8-NPs, offering an option technique for ACP-based delivery.

Electrochemical Sensors Based on Self-Assembling Peptide/Carbon Nanotube Nanocomposites for Sensitive Detection of Bisphenol A.

In this study, a cationic amphiphilic self-assembling peptide (SAP) Z23 was designed, and a simple bisphenol a (BPA) sensor, based on SAP Z23/multiwalled carbon nanotubes (Z23/MWCNTs) composite, was successfully fabricated on the surface of a glassy carbon electrode (GCE). The composite material was formed by π-π stacking interaction between the aromatic group on the hydrophobic side of Z23 and the side-wall of MWCNTs, with the charged hydrophilic group of Z23 exposed. During the electrocatalytic process of BPA, a synergistic effect was observed between Z23 and MWCNTs. The current response of the sensor based on composite material was 3.24 times that of the MWCNTs-modified electrode, which was much higher than that of the peptide-based electrode. Differential pulse voltammetry (DPV) was used to optimize the experimental conditions affecting the analytical performance of the modified electrode. Under optimal conditions, the linear range of the sensor was from 10 nM to 100 μM by amperometric measurement with sensitivity and limit of detection (LOD) at 6.569 μAμM-1cm-2 and 1.28 nM (S/N = 3), respectively. Consequently, the sensor has excellent electrochemical performance and is easy to fabricate, making it a good prospect in the field of electrochemical detection in the future.

The current landscape of the antimicrobial peptide melittin and its therapeutic potential.

Melittin, a main component of bee venom, is a cationic amphiphilic peptide with a linear α-helix structure. It has been reported that melittin can exert pharmacological effects, such as antitumor, antiviral and anti-inflammatory effects in vitro and in vivo. In particular, melittin may be beneficial for the treatment of diseases for which no specific clinical therapeutic agents exist. Melittin can effectively enhance the therapeutic properties of some first-line drugs. Elucidating the mechanism underlying melittin-mediated biological function can provide valuable insights for the application of melittin in disease intervention. However, in melittin, the positively charged amino acids enables it to directly punching holes in cell membranes. The hemolysis in red cells and the cytotoxicity triggered by melittin limit its applications. Melittin-based nanomodification, immuno-conjugation, structural regulation and gene technology strategies have been demonstrated to enhance the specificity, reduce the cytotoxicity and limit the off-target cytolysis of melittin, which suggests the potential of melittin to be used clinically. This article summarizes research progress on antiviral, antitumor and anti-inflammatory properties of melittin, and discusses the strategies of melittin-modification for its future potential clinical applications in preventing drug resistance, enhancing the selectivity to target cells and alleviating cytotoxic effects to normal cells.

Synthesis and Biological Properties of Polyphenol-Containing Linear and Dendrimeric Cationic Peptides.

Natural polyphenols are promising compounds for the pharmacological control of oxidative stress in various diseases. However, low bioavailability and rapid metabolism of polyphenols in a form of glycosides or aglycones have stimulated the search for the vehicles that would provide their efficient delivery to the systemic circulation. Conjugation of polyphenols with cationic amphiphilic peptides yields compounds with a strong antioxidant activity and ability to pass through biological barriers. Due to a broad range of biological activities characteristic of polyphenols and peptides, their conjugates can be used in the antioxidant therapy, including the treatment of viral, oncological, and neurodegenerative diseases. In this work, we synthesized linear and dendrimeric cationic amphiphilic peptides that were then conjugated with gallic acid (GA). GA is a non-toxic natural phenolic acid and an important functional element of many flavonoids with a high antioxidant activity. The obtained GA-peptide conjugates showed the antioxidant (antiradical) activity that exceeded 2-3 times the antioxidant activity of ascorbic acid. GA attachment had no effect on the toxicity and hemolytic activity of the peptides. GA-modified peptides stimulated the transmembrane transfer of the pGL3 plasmid encoding luciferase reporter gene, although GA attachment at the N-terminus of peptides reduced their transfection activity. Several synthesized conjugates demonstrated the antibacterial activity in the model of Escherichia coli Dh5α growth inhibition.

A cationic amphiphilic peptide chaperone rescues Aβ42 aggregation and cytotoxicity.

Directing Aβ42 to adopt a conformation that is free from aggregation and cell toxicity is an attractive and viable strategy to design therapeutics for Alzheimer's disease. Over the years, extensive efforts have been made to disrupt the aggregation of Aβ42 using various types of inhibitors but with limited success. Herein, we report the inhibition of aggregation of Aβ42 and disintegration of matured fibrils of Aβ42 into smaller assemblies by a 15-mer cationic amphiphilic peptide. The biophysical analysis comprising thioflavin T (ThT) mediated amyloid aggregation kinetic analysis, dynamic light scattering, ELISA, AFM, and TEM suggested that the peptide effectively disrupts Aβ42 aggregation. The circular dichroism (CD) and 2D-NMR HSQC analysis reveal that upon interaction, the peptide induces a conformational change in Aβ42 that is free from aggregation. Further, the cell assay experiments revealed that this peptide is non-toxic to cells and also rescues the cells from the toxicity of Aβ42. Peptides with a shorter length displayed either weak or no inhibitory effect on Aβ42 aggregation and cytotoxicity. These results suggest that the 15-residue cationic amphiphilic peptide reported here may serve as a potential therapeutic candidate for Alzheimer's disease.

Self-assembled aggregates based on cationic amphiphilic peptides: structural insight.

Short and ultra-short peptides have recently emerged as suitable building blocks for the fabrication of self-assembled innovative materials. Peptide aggregation is strictly related to the amino acids composing the sequence and their capability to establish intermolecular interactions. Additional structural and functional properties can also be achieved by peptide derivatization (e.g. with polymeric moieties, alkyl chains or other organic molecules). For instance, peptide amphiphiles (PAs), containing one or more alkyl tails on the backbone, have a propensity to form highly ordered nanostructures like nanotapes, twisted helices, nanotubes and cylindrical nanostructures. Further lateral interactions among peptides can also promote hydrogelation. Here we report the synthesis and the aggregation behaviour of four PAs containing cationic tetra- or hexa-peptides (C19-VAGK, C19-K1, C19-K2 and C19-K3) derivatized with a nonadecanoic alkyl chain. In their acetylated (Ac-) or fluorenylated (Fmoc-) versions, these peptides previously demonstrated the ability to form biocompatible hydrogels potentially suitable as extracellular matrices for tissue engineering or diagnostic MRI applications. In the micromolar range, PAs self-assemble in aqueous solution into nanotapes, or small clusters, resulting in high biocompatibility on HaCat cells up to 72 hours of incubation. Moreover, C19-VAGK also forms a gel at a concentration of 5 wt%.

Split luciferase-based estimation of cytosolic cargo concentration delivered intracellularly via attenuated cationic amphiphilic lytic peptides

Intracellular delivery of biomacromolecules is challenging as these molecules are taken up by cells and encapsulated into vesicular compartments called endosomes, and the fraction of molecules that are translocated to the cytosol are particularly important to obtain desired biological responses. This study aimed to estimate the cytosolic concentrations of intracellularly delivered peptides and proteins to aid the design of novel and effective biopharmaceutical delivery systems. To this end, we employed the split NanoLuc luciferase system, using the 11-residue HiBiT peptide segment as a probe for the delivered molecules in cells expressing the complementary LgBiT protein segment. The efficacy in cytosolic HiBiT delivery was determined by measuring the resultant luciferase activity when the HiBiT segment delivered into the cytosol forms a complex with LgBiT. Mean cytosolic HiBiT concentration was calculated using cell number and cell volume analysis. L17E and HAad peptides, developed in our laboratory for intracellular protein delivery, yielded approximately 6-fold cellular HiBiT concentrations than that obtained in their absence.

Peptide-functionalised magnetic silk nanoparticles produced by a swirl mixer for enhanced anticancer activity of ASC-J9

Silk fibroin is an FDA approved biopolymer for clinical applications with great potential in nanomedicine. However, silk-based nanoformulations are still facing several challenges in processing and drug delivery efficiency (such as reproducibility and targetability), especially in cancer therapy. To address these challenges, robust and controllable production methods are required for generating nanocarriers with desired properties. This study aimed to develop a novel method for the production of peptide-functionalized magnetic silk nanoparticles with higher selectivity for cancer cells for targeted delivery of the hydrophobic anticancer agent ASC-J9. A new microfluidic device with a swirl mixer was designed to fabricate magnetic silk nanoparticles (MSNP) with desired size and narrow size distribution. The surface of MSNPs was functionalized with a cationic amphiphilic anticancer peptide, G(IIKK)3I-NH2 (G3), to enhance their selectivity towards cancer cells. The G3-MSNPs increased the cellular uptake and anticancer activity of G3 in HCT 116 colorectal cancer cells compared to free G3. Moreover, the G3-MSNPs exhibited considerably higher cellular uptake and cytotoxicity in HCT 116 colorectal cancer cells compared to normal cells (HDFs). Encapsulating ASC-J9 in G3-MSNPs resulted in augmented anticancer activity compared to free ASC-J9 and non-functionalized ASC-J9 loaded MSNPs within its biological half-life. Hence, functionalizing MSNPs with G3 enabled targeted delivery of ASC-J9 to cancer cells and enhanced its anticancer effect. Functionalization of nanoparticles with anticancer peptides could be regarded as a new strategy for targeted delivery and enhanced efficiency of anticancer drugs. Furthermore, the microfluidic device introduced in this paper offers a robust and reproducible method for fabrication of small sized homogenous nanoparticles.

L17ER4: A cell-permeable attenuated cationic amphiphilic lytic peptide

We have developed a series of attenuated cationic amphiphilic lytic (ACAL) peptides that can efficiently bring immunoglobulin G (IgG) and other functional proteins into cells. Delivery is generally achieved through the coadministration of ACAL peptides with cargo proteins. However, conjugation of ACAL peptides with cargos may be a promising approach for in vivo application to link in vivo outcomes of ACAL peptides and cargos. This study describes the creation of a new cell-permeable ACAL peptide, L17ER4. L17E is an optimized prototype of ACAL peptides previously developed in our laboratory for efficient delivery of IgGs into cells. Delivery was improved by functionalizing L17E with a tetra-arginine (R4) tag. Compared to the use of R8, a representative cell-penetrating peptide with high intracellular delivery efficacy, conjugation with L17ER4 afforded approximately four-fold higher cellular uptake of model small-molecule cargos (fluorescein isothiocyanate and HiBiT peptide). L17ER4 was also able to deliver proteins to cells. Fused with L17ER4, Cre recombinase was delivered into cells. Intracerebroventricular injection of Cre-L17ER4 into green red reporter mice, R26GRR, led to significant in vivo gene recombination in ependymal cells, suggesting that L17ER4 may be used as a cell-penetrating peptide for delivering protein therapeutics into cells in vivo.

Rationally designed cationic amphiphilic peptides for selective gene delivery to cancer cells

Gene therapy has gained increasing attention as an alternative to pharmacotherapy for treatment of various diseases. The extracellular and intracellular barriers to gene delivery necessitate the use of gene vectors which has led to the development of myriads of gene delivery systems. However, many of these gene delivery systems have pitfalls such as low biocompatibility, low loading efficiency, low transfection efficiency, lack of tissue selectivity and high production costs. Herein, we report the development of a new series of short cationic amphiphilic peptides with anticancer activity for selective delivery of small interfering RNA (siRNA) and antisense oligodeoxynucleotides (ODNs) to cancer cells. The peptides consist of alternating dyads of hydrophobic (isoleucine (I) or leucine (L)) and hydrophilic (arginine (R) or lysine (L)) amino acids. The peptides exhibited higher preference for transfection of HCT 116 colorectal cancer cells compared to human dermal fibroblasts (HDFs) and induced higher level of gene silencing in the cancer cells. The nucleic acid complexation and transfection efficiency of the peptides was a function of their secondary structure, their hydrophobicity and their C-terminal amino acid. The peptides containing L in their hydrophobic domain formed stronger complexes with siRNA and successfully delivered it to the cancer cells but were unable to release their cargo inside the cells and therefore could not induce any gene silencing. On the contrary, the peptides containing I in their hydrophobic domain were able to release their associated siRNA and induce considerable gene silencing in cancer cells. The peptides exhibited higher selectivity for colorectal cancer cells and induced less gene silencing in fibroblasts compared to the lipid-based commercial transfection reagent DharmaFECT™ 1. The results from this study can serve as a tool for rational design of new peptide-based gene vectors for high selective gene delivery to cancer cells.

Turn-folded magainin lipopeptide analog induces cytoplasmic vacuoles in MDA-MB-231 cells through G2-phase arrest

Selective induced non-canonical programmed deaths in the lipid raft type 1-enriched MDA-MB-231 is a promising treatment approach. Cationic amphiphilic peptides conjugated to relatively long fatty acyl chains that tend to self-aggregate are prone to upregulate necroptotic and paraptotic signaling. We investigated the toxic effects of an N-terminally palmitoylated magainin derivate (P1MK5E) in the MDA-MB-231 cells in relation to its structure at molecular level. The modeling showed that the palmitoylation reinforces a turn-like structural motif in the lipopeptide which is likely required for its activity. P1MK5E triggered intracellular generation of reactive oxygen species (ROS), G2-phase arrest, mitochondrial membrane potential (ΔΨmt) disturbance and presumable flopping of phosphatidylserine (PtdSer) to the cancer cell membrane outer surface in a comparable manner to doxorubicin (DOX) that induces apoptotic signaling. Despite forming extensive congregates of different sizes at the cell surface, P1MK5E had little impacts on the MDA-MB-231 membrane integrity. The cell death upon exposure to the lipopeptide was, however, caspase 3 independent and characterized by cytoplasmic vacuolation and no distinct nuclear fragmentation that is to be privileged in the treatment of apoptotic resistance pathways in triple-negative breast cancers (TNBCs).

Correlation between the secondary structure and surface activity of β-sheet forming cationic amphiphilic peptides and their anticancer activity

Cancer is one of the main causes of death worldwide. The current cancer treatment strategies often lack selectivity for cancer cells resulting in dose-limiting adverse effects and reduced quality of life. Recently, anticancer peptides (ACPs) have emerged as an alternative treatment with higher selectivity, less adverse effects, and lower propensity for drug resistance. However, most of the current studies on the ACPs are focused on α-helical ACPs and there is lack of systematic studies on β-sheet forming ACPs. Herein we report the development of a new series of rationally designed short cationic amphiphilic β-sheet forming ACPs and their structure activity relationship. The peptides had the general formula (XY1XY2)3, with X representing hydrophobic amino acids (isoleucine (I) or leucine (L)), Y1 and Y2 representing cationic amino acids (arginine (R) or lysine (K)). The cytotoxicity of the designed ACPs in HCT 116 colorectal cancer, HeLa cervical cancer and human dermal fibroblast (HDF) cells was assessed by MTT test. The physicochemical properties of the peptides were characterized by various techniques including RP-HPLC, LC-MS, and Circular Dichroism (CD) spectroscopy. The surface activity of the peptides at the air-water interface and their interaction with the lipid monolayers as models for cell membranes were studied by Langmuir trough. The peptides consisting of I with R and K had selective anticancer activity while the combination of L and R diminished the anticancer activity of the peptides but rendered them more toxic to HDFs. The anticancer activity of the peptides was directed by their surface activity (amphiphilicity) and their secondary structure in hydrophobic surfaces including cancer cell membranes. The selectivity of the peptides for cancer cells was a result of their higher penetration into cancer cell membranes compared to normal cell membranes. The peptides exerted their anticancer activity by disrupting the mitochondrial membranes and eventually apoptosis. The results presented in this study provide an insight into the structure-activity relationship of this class of ACPs which can be employed as guidance to design new ACPs with improved anticancer activity and lower toxicity against normal cells.

Влияние применения пробиотического препарата, содержащего штамм Lactobacillus rhamnosus GG, на уровни HbD-2 и LL-37 в секрете верхних дыхательных путей и респираторную заболеваемость у детей, больных бронхиальной астмой и аллергическим ринитом

Актуальность. На сегодняшний день аллергические заболевания респираторного тракта, в частности бронхиальная астма и аллергический ринит, у детей являются актуальной медико-социальной проблемой, ассоциированной с высоким риском инвалидизации, существенным снижением качества жизни пациентов и их семей, а также значительной финансовой нагрузкой на пациентов и государство. Бронхиальная астма и аллергический ринит часто сосуществуют, обременяя течение друг друга. Дети, больные респираторными аллергическими заболеваниями, являются особенно уязвимыми к развитию острой респираторной вирусной инфекции (ОРВИ), а респираторные вирусы, в свою очередь, играют важную роль в патогенезе бронхиальной астмы и аллергического ринита, способствуя развитию заболеваний и выступая триггерами их обострений. Одной из возможных причин склонности к частым ОРВИ у детей с аллергической патологией дыхательной системы может быть недостаточность неспецифических факторов мукозального иммунитета респираторного тракта — эндогенных катионоактивных амфифильных антимикробных пептидов, в частности кателицидина (LL-37) и человеческих дефензинов. По данным ряда исследований, эти антимикробные пептиды проявляют противовирусное, антимикробное и иммуномодулирующее действие. При этом данных о состоянии продукции антимикробных пептидов и их влиянии на респираторную заболеваемость у детей с аллергическими заболеваниями в современной литературе недостаточно. В то же время в ряде литературных источников описано положительное влияние отдельных пробиотических штаммов, в частности Lactobacillus rhamnosus GG, на общую резистентность к респираторной вирусной инфекции и профилактику атопических заболеваний. Целью нашей работы стало изучение уровней антимикробных пептидов (человеческого β-дефензина 2 (HbD-2) и LL-37) в секрете слизистых оболочек верхних дыхательных путей у детей с бронхиальной астмой и аллергическим ринитом, выяснение их роли в защите от респираторной вирусной инфекции у данного контингента больных и оценка эффективности применения пробиотического препарата, содержащего Lactobacillus rhamnosus GG, с целью профилактики ОРВИ и снижения частоты вирус-индуцированных обострений аллергической патологии. Материалы и методы. Нами было проведено клинико-лабораторное обследование 76 детей в возрасте от 7 до 17 лет, из которых у 24 был диагностирован аллергический ринит, у 28 детей — бронхиальная астма, а у 24 — бронхиальная астма и аллергический ринит. Группу контроля составили 20 клинически здоровых детей соответствующего возраста и пола. Кроме общепринятых клинических, методы исследования включали анализ паттернов респираторной заболеваемости, определение уровней антимикробных пептидов LL-37, HbD-2 в секрете верхних дыхательных путей методами иммуноферментного и статистического анализа. Результаты. Установлено, что дети с аллергическими заболеваниями респираторного тракта характеризуются большей частотой ОРВИ (на 30 %) с более частым вовлечением в воспалительный процесс нижних дыхательных путей (на 72 %), что обусловливает более длительную продолжительность заболеваний (на 95 %) по сравнению со здоровыми детьми. У детей с аллергическим ринитом и бронхиальной астмой обнаружено существенное снижение уровней антимикробных пептидов в секрете верхних дыхательных путей по сравнению с группой контроля. На уровни антимикробных пептидов в секрете верхних дыхательных путей в наибольшей степени негативно влияет степень активности аллергического воспаления, сопровождающегося отсутствием контроля симптомов, а положительно — прием препаратов базисной терапии и отсутствие симптомов. Вместе с тем даже при наличии полного контроля симптомов аллергических заболеваний, то есть при минимальном уровне аллергического воспаления в дыхательных путях, уровни антимикробных пептидов были достоверно ниже, чем у детей контрольной группы. Установлено, что существует обратная связь между уровнями антимикробных пептидов и частотой и продолжительностью ОРВИ у детей с аллергическими заболеваниями, которая в наибольшей степени выражена при бронхиальной астме. Выводы. Прием пробиотического препарата, содержащего штамм Lactobacillus rhamnosus GG, в течение 1 месяца дополнительно к базисной терапии аллергического ринита и бронхиальной астмы способствовал достоверному повышению уровней HbD-2 (в среднем на 27 %) и LL-37 (в среднем на 60 %) в секрете верхних дыхательных путей, что сопровождалось снижением частоты ОРВИ в среднем на 26 % (в том числе и эпизодов с привлечением нижних дыхательных путей), уменьшением средней продолжительности ОРВИ на 22 % в течение следующего года и снижением вирус-индуцированных обострений на 25,7 %.

Mitochondrial Voltage-Dependent Anion Channel 1-Hexokinase-II Complex-Targeted Strategy for Melanoma Inhibition Using Designed Multiblock Peptide Amphiphiles.

Targeted therapies of melanoma are of urgent need considering the resistance of this aggressive type of cancer to chemotherapeutics. The voltage-dependent anion channel 1 (VDAC1)-hexokinase-II (HK-II) complex is an emerging target for novel anticancer therapies based on induced mitochondria-mediated apoptosis. The low cell membrane permeability of the anticancer 12-mer peptide N-Ter (RDVFTKGYGFGL) derived from the N-terminal fragment of the VDAC1 protein impedes the intracellular targeting. Here, novel multiblock VDAC1-derived cationic amphiphilic peptides (referred to as Pal-N-Ter-TAT, pFL-N-Ter-TAT, and Pal-pFL-N-Ter-TAT) are designed with a self-assembly propensity and cell-penetrating properties. The created multiblock amphiphilic peptides of partial α-helical conformations form nanoparticles of ellipsoid-like shapes and are characterized by enhanced cellular uptake. The amphiphilic peptides can target mitochondria and dissociate the VDAC1-HK-II complex at the outer mitochondrial membrane, which result in mitochondria-mediated apoptosis. The latter is associated with decrease of the mitochondrial membrane potential, cytochrome c release, and changes of the expression levels of the apoptotic proteins in A375 melanoma cells. Importantly, the mitochondrial VDAC1-derived amphiphilic peptides have a comparable IC50 value for melanoma cells to a small-molecule drug, sorafenib, which has been previously used in clinical trials for melanoma. These results demonstrate the potential of the designed peptide constructs for efficient melanoma inhibition.

Titelbild: Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides (Angew. Chem. 36/2021)

Große Mengen von Antikörpern können aus Koazervaten (Flüssigkeitströpfchen), die durch Mischen eines fluoreszenzmarkierten Antikörpers und eines Transportpeptids gebildet werden, schnell in Zellen eingebracht werden, wie Shiroh Futaki und Mitarbeiter im Forschungsartikel auf S. 19957 berichten. Der Vorgang geht mit strukturellen Veränderungen der Zellmembranen einher, ähnlich einem Tintentropfen im Wasser. Das Titelbild illustriert den intrazellulären Transport von Antikörpern durch ein Koazervat. Mit dieser Forschung wurde der erste intrazelluläre Transport von Antikörpern mittels Flüssig-Flüssig-Phasentrennung realisiert.

Cover Picture: Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides (Angew. Chem. Int. Ed. 36/2021)

Large amounts of antibodies can be rapidly delivered into cells from coacervates (liquid droplets) formed by mixing a fluorescently labeled antibody and a delivery peptide, as reported by Shiroh Futaki et al. in their Research Article on page 19804. The mode of delivery is a mysterious phenomenon, which is accompanied by structural changes of the cell membranes as for a drop of ink on a water surface. The cover illustration shows a representation of the intracellular delivery of antibodies by coacervate. This research has realized the first intracellular delivery of antibodies using liquid–liquid phase separation.

Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides.

Fc region binding peptide conjugated with attenuated cationic amphiphilic lytic peptide L17E trimer [FcB(L17E)3 ] was designed for immunoglobulin G (IgG) delivery into cells. Particle-like liquid droplets were generated by mixing Alexa Fluor 488 labeled IgG (Alexa488-IgG) with FcB(L17E)3 . Droplet contact with the cellular membrane led to spontaneous influx and distribution of Alexa488-IgG throughout cells in serum containing medium. Involvement of cellular machinery accompanied by actin polymerization and membrane ruffling was suggested for the translocation. Alexa488-IgG negative charges were crucial in liquid droplet formation with positively charged FcB(L17E)3 . Binding of IgG to FcB(L17E)3 may not be necessary. Successful intracellular delivery of Alexa Fluor 594-labeled anti-nuclear pore complex antibody and anti-mCherry-nanobody tagged with supernegatively charged green fluorescence protein allowed binding to cellular targets in the presence of FcB(L17E)3 .

Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides

AbstractFc region binding peptide conjugated with attenuated cationic amphiphilic lytic peptide L17E trimer [FcB(L17E)3] was designed for immunoglobulin G (IgG) delivery into cells. Particle‐like liquid droplets were generated by mixing Alexa Fluor 488 labeled IgG (Alexa488‐IgG) with FcB(L17E)3. Droplet contact with the cellular membrane led to spontaneous influx and distribution of Alexa488‐IgG throughout cells in serum containing medium. Involvement of cellular machinery accompanied by actin polymerization and membrane ruffling was suggested for the translocation. Alexa488‐IgG negative charges were crucial in liquid droplet formation with positively charged FcB(L17E)3. Binding of IgG to FcB(L17E)3 may not be necessary. Successful intracellular delivery of Alexa Fluor 594‐labeled anti‐nuclear pore complex antibody and anti‐mCherry‐nanobody tagged with supernegatively charged green fluorescence protein allowed binding to cellular targets in the presence of FcB(L17E)3.