Presence Of Cell-penetrating Peptides Research Articles

In Silico Prediction of Anti-Infective and Cell-Penetrating Peptides from Thalassophryne nattereri Natterin Toxins.

The therapeutic potential of venom-derived peptides, such as bioactive peptides (BAPs), is determined by specificity, stability, and pharmacokinetics properties. BAPs, including anti-infective or antimicrobial peptides (AMPs) and cell-penetrating peptides (CPPs), share several physicochemical characteristics and are potential alternatives to antibiotic-based therapies and drug delivery systems, respectively. This study used in silico methods to predict AMPs and CPPs derived from natterins from the venomous fish Thalassophryne nattereri. Fifty-seven BAPs (19 AMPs, 8 CPPs, and 30 AMPs/CPPs) were identified using the web servers CAMP, AMPA, AmpGram, C2Pred, and CellPPD. The physicochemical properties were analyzed using ProtParam, PepCalc, and DispHred tools. The membrane-binding potential and cellular location of each peptide were analyzed using the Boman index by APD3, and TMHMM web servers. All CPPs and two AMPs showed high membrane-binding potential. Fifty-four peptides were located in the plasma membrane. Peptide immunogenicity, toxicity, allergenicity, and ADMET parameters were evaluated using several web servers. Sixteen antiviral peptides and 37 anticancer peptides were predicted using the web servers Meta-iAVP and ACPred. Secondary structures and helical wheel projections were predicted using the PEP-FOLD3 and Heliquest web servers. Fifteen peptides are potential lead compounds and were selected to be further synthesized and tested experimentally in vitro to validate the in silico screening. The use of computer-aided design for predicting peptide structure and activity is fast and cost-effective and facilitates the design of potent therapeutic peptides. The results demonstrate that toxins form a natural biotechnological platform in drug discovery, and the presence of CPP and AMP sequences in toxin families opens new possibilities in toxin biochemistry research.

Spectroscopic and Microscopic Approach to Monitor the Changes in Bilayer Rigidity during Cell Penetrating Peptide Induced Self-Reproduction of Phospholipid Vesicles

Understanding peptide-membrane interaction in view of structural change of lipid bilayer is essential to develop new therapeutic strategies. Though different mechanisms are proposed for cell penetrating peptides (CPPs) penetration in lipid bilayer, the exact mechanism of cellular uptake of CPPs remains a significant unanswered piece of puzzle. Here, we report a novel observation that model phospholipid vesicles self-reproduce to generate unilamellar daughter vesicles in presence of a CPP, nonaarginine (R9). Fluorescence lifetime image analysis (FLIM) exquisitely captures the changes of L-α-phosphatidylcholine (LAPC) bilayer in different times and also quantifies the changes through valuable lifetime distributions obtained. Mean square displacement (MSD) calculations from FLIM images of single vesicle trajectory establish CPP induced self-reproduction of LAPC vesicles. Heterogeneous nature of lipid bilayer after 1 hour of R9 addition is observed from fluorescence correlation spectroscopy (FCS) which supposed to consider as the starting point of “mother vesicles” reproduction. Solvation dynamic study delineates the change in dynamics of the encapsulated water inside vesicles which also states different rigidity of lipid bilayer in different states of vesicle self-reproduction. Fluorescence anisotropy image analysis provides information regarding change in lipid bilayer rigidity by quantifying the rotational motion of the fluorophore in presence of perturbation of CPPs. From these experimental observations, we are able to establish phospholipid vesicles self-reproduction in presence of CPPs which may be considered as a possible route of CPPs action to deliver cargos to cell interior through hydrophobic barriers. Overall, our results provide an experimental underpinning of the role of lipid bilayer structural changes in self-reproduction which can exhibit great potential to interpret the protein-lipid interaction in emergence of life.

Region-Dependent Role of Cell-Penetrating Peptides in Insulin Absorption Across the Rat Small Intestinal Membrane.

We have reported that the cell-penetrating peptide (CPP) penetratin acts as a potential absorption enhancer in oral insulin delivery systems and that this action occurs through noncovalent intermolecular interactions. However, the region-dependent role of CPPs in intestinal insulin absorption has not been clarified. To identify the intestinal region where CPPs have the most effect in increasing insulin absorption, the region-dependent action of penetratin was investigated using in situ closed intestinal loops in rats. The order of the insulin area under the insulin concentration-time curve (AUC) increase effect by L-penetratin was ileum > jejunum > duodenum > colon. By contrast, the AUC order after coadministration of insulin with D-penetratin was colon > duodenum ≥ jejunum and ileum. We also compared the effects of the L- and D-forms of penetratin, R8, and PenetraMax on ileal insulin absorption. Along with the CPPs used in this study, L- and D-PenetraMax produced the largest insulin AUCs. An absorption study using ilea pretreated with CPPs showed that PenetraMax had no irreversible effect on the intestinal epithelial membrane. The degradation of insulin in the presence of CPPs was assessed in rat intestinal enzymatic fluid. The half-life (t 1/2) of insulin increased from 14.5 to 23.7 and 184.7 min in the presence of L- and D-PenetraMax, respectively. These enzymatic degradation-resistant effects might contribute partly to the increased ileal absorption of insulin induced by D-PenetraMax. In conclusion, this study demonstrated that the ability of the L- and D-forms of penetratin to increase intestinal insulin absorption was maximal in the ileum and the colon, respectively, and that D-PenetraMax is a powerful but transient enhancer of oral insulin absorption.

Targeting cytokine expression in glial cells by cellular delivery of an NF-κB decoy

Inhibition of nuclear factor (NF)-kappaB has emerged as an important strategy for design of anti-inflammatory therapies. In neurodegenerative disorders like Alzheimer's disease, inflammatory reactions mediated by glial cells are believed to promote disease progression. Here, we report that uptake of a double-stranded oligonucleotide NF-kappaB decoy in rat primary glial cells is clearly facilitated by noncovalent binding to a cell-penetrating peptide, transportan 10, via a complementary peptide nucleic acid (PNA) sequence. Fluorescently labeled oligonucleotide decoy was detected in the cells within 1 h only when cells were incubated with the decoy in the presence of cell-penetrating peptide. Cellular delivery of the decoy also inhibited effects induced by a neurotoxic fragment of the Alzheimer beta-amyloid peptide in the presence of the inflammatory cytokine interleukin (IL)-1beta. Pretreatment of the cells with the complex formed by the decoy and the cell-penetrating peptide-PNA resulted in 80% and 50% inhibition of the NF-kappaB binding activity and IL-6 mRNA expression, respectively.