Stabilizing Scaffold for Short Peptides Based on Knottins

BACKGROUND

Bombesin (BBN) is a short peptide with a high affinity for receptors that are expressed on the surface of various types of cancer cells. However, a full length BBN molecule has low in vivo stability.

OBJECTIVE

In our study, we propose the use of peptide toxins, derived from animal and plant toxins, as scaffold molecules to enhance the bioavailability and stability of bombesin. These peptides possess a unique structure known as an inhibitory cystine knot.

METHODS

We synthesized structures in which short bombesin was incorporated into various domains of arthropod and plant toxins using solid-phase peptide synthesis. The stability under different conditions was assessed through high-performance liquid chromatography, and binding to cell cultures expressing the bombesin receptor was analyzed. Additionally, toxicity to cell cultures was evaluated using fluorescence microscopy.

RESULTS

The data obtained demonstrated that placing the short peptide between the first and second cysteine residues in arachnid toxins results in increased in vitro stability and bioavailability, as well as low cytotoxicity.

CONCLUSION

Arachnid toxins with an inhibitory cystine knot can be considered as a scaffold for increasing the stability of therapeutic peptides.

Protective Effect of Peptide Calcium Channel Blocker Omega-Hexatoxin-Hv1a on Epithelial Cell during Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) is a common phenomenon that develops both from natural causes and during major operations. Many intracellular processes mediated by calcium ions are involved in the development of IRI. Currently, chemical calcium channel blockers are used but they have a number of limitations. In this article, we study the effect of the omega-hexatoxin-Hv1a peptide toxin, an alternative to chemical calcium channel blockers, on the mechanisms of IRI development in epithelial cell culture. The toxin was produced using solid phase peptide synthesis. IRI was caused by deprivation of glucose, serum and oxygen. The data obtained demonstrate that the omega-hexatoxin-Hv1a toxin in nanomolar concentrations is able to prevent the development of apoptosis and necrosis in epithelial cells by reducing the concentration of calcium, sodium and potassium ions, as well as by delaying rapid normalization of the pH level, affecting the mitochondrial potential and oxidative stress. This toxin can be used as an alternative to chemical calcium channel blockers for preventing tissue and organ IRI due to its low-dose requirement and high bioavailability.

Peptide Sodium Channels Modulator Mu-Agatoxin-Aa1a Prevents Ischemia-Reperfusion Injury of Cells

Ischemia-reperfusion injury (IRI) is an irreversible functional and structural injury. Restoration of normal oxygen concentration exacerbates the emergence and development of deadly cells. One of the possible moments of reperfusion damage to cells is an increase in the intracellular concentration of sodium ions. In this article, we study the mu-agatoxin-Aa1a, a modulator of sodium channels, on the processes of IRI cells damage. The toxin was synthesized using an automatic peptide synthesizer. Hypoxia was induced by reducing the content of serum and oxygen in the CHO-K1 culture. The influence of the toxin on the level of apoptosis; intracellular concentration of sodium, calcium, and potassium ions; intracellular pH; totality of reactive oxygen species (ROS), nitric oxide (NO), and ATP; and changes in the mitochondrial potential were studied. The experiments performed show that mu-agatoxin-Aa1a effectively prevents IRI of cells. Toxin reduces the level of apoptosis and prevents a decrease in the intracellular concentration of sodium and calcium ions during IRI. Mu-agatoxin-Aa1a contributes to the maintenance of elevated intracellular pH, reduces the intracellular concentration of ROS, and prevents the decrease in intracellular NO concentration and mitochondrial potential under conditions of reoxygenation/reperfusion. An analysis of experimental data shows that the mu-agatoxin-Aa1a peptide has adaptogenic properties. In the future, this peptide can be used to prevent ischemia/reperfusion tissue damage different genesis.

The effect of chromosome abnormalities on expression of SnoRNA in radioresistant and radiosensitive cell lines after irradiation

In this paper, we have studied the role of chromosomal abnormalities in the expression of small nucleolar RNAs (snoRNAs) of radioresistant (K562) and radiosensitive (HL-60) leukemia cell line. Cells were exposed to an X-ray dose of 4 Gy. SnoRNA expression was investigated using NGS sequencing. The distribution of expressed snoRNAs on chromosomes has been found to be different for two cell lines. The most significant differences in the expression of snoRNAs were found in the K562 cell line based on the analysis of the dynamics of log2fc values. The type of clustering, the number and type of snoRNAs slightly differed in the chromosomes with trisomy and monosomy and had a pronounced difference in pairs with marker chromosomes in both cell lines. In this study, we have demonstrated that chromosomal abnormalities alter the expression of snoRNA after irradiation. Trisomies and monosomies do not have such a noticeable effect on the expression of snoRNAs as the presence of marker chromosomes.

Arthropod toxins inhibiting Ca2+ and Na+ channels prevent AC-1001 H3 peptide-induced apoptosis

Peptide toxins of arthropods are one of the potential sources of bioactive substances. Toxins are able to bind to calcium channels and block them. Ca²⁺ ions play an important role in many cell processes, in particular, in apoptosis. In this work, we study the effect of some arthropod toxins on intracellular processes associated with the induction of apoptosis. Synthetic analogs of U₅ -scytotoxin-Sth1a, ω-hexatoxin-Hv1a, ω-theraphotoxin-Hhn2a, and μ-agatoxin-Aa1a toxins-inhibitors of calcium L, P, and Q channels and sodium channels were used in the study. Apoptosis was induced by AC-1001 H3 peptide. We study the effect of toxins on the level of apoptosis, ROS, mitochondrial potential, GSH, and ATP in CHO-K1 cells. We show that all the tested toxins are able to dose dependently block the induction of apoptosis triggered by AC-1001 H3 and reduce the level of natural apoptosis in CHO-K1 cells. Cell incubation with apoptosis inducer AC-1001 H3 in the presence and absence of toxins causes an increase in the intracellular concentrations of ROS, ATP, and mitochondrial potential and decreases the GSH concentration. The present study reveals the antiapoptotic effect of a number of arthropod peptide toxins. The toxins studied can represent a novel approach used in the treatment of pathologies associated with the activation of apoptotic mechanisms.