Biochemistry (Moscow)最新文献

Proline-rich antimicrobial peptides (PrAMPs) are promising compounds for overcoming antibiotic resistance, one of the global health threats, and stand out from other types of AMPs by their high safety profile. The main cellular target of PrAMPs, like most modern antibiotics, is the conservative cellular structure – the ribosome. PrAMPs bind in the ribosomal tunnel, forming multiple interactions with nucleotides of 23S rRNA, and are divided into two classes depending on their mechanism of action: inhibition of elongation or termination. The N-terminal part of the peptides, which is important for the activity of class I peptides, extends into the A-site pocket, preventing the binding of aminoacyl-tRNA. A new family of PrAMPs, rumicidins, was discovered using genomic search methods. Its representatives have the longest N-terminal part, as well as a unique pair of amino acids Trp23 and Phe24 at the C-terminus. The Trp-Phe dyad forms a spacer at the constriction site of the ribosomal tunnel, stabilizing the binding and leading to increased antibacterial activity. New structural studies of the class I peptide Bac5 have demonstrated its ability to disrupt the correct positioning of the CCA-end of the P-site tRNA in the peptidyltransferase center of the ribosome, which can affect the assembly of functional initiation complexes. Class II PrAMPs, according to new data, have additional binding sites on the ribosome and have a complex effect on the bacterial cell: they disrupt the termination of protein synthesis, block the cellular ribosome release system, prevent the correct assembly of the 50S ribosomal subunits, and, possibly, affect the first stage of translocation. Recent studies expand our understanding of the antimicrobial activity of PrAMPs and contribute to the creation of future therapeutic drugs based on AMPs.

Double-strand DNA break (DSB) repair mechanisms vary in their ability to prevent errors during end joining. The joining of DSBs on different chromosomes can result in translocations, potentially leading to tumorigenesis. This review examines the main mechanisms of DSB repair and factors influencing their selection, as well as contribution of these mechanisms to the chromosomal rearrangements in human cells.

Methyltransferases that modify spliceosomal small nuclear RNAs (snRNAs) play a crucial role in the cell by ensuring proper maturation of snRNAs, which is essential for optimal function of spliceosome. In this study, we investigated the enzyme METTL4, which catalyzes N6-methylation of 2′-O-methyladenosine at position 30 of U2 snRNA. Function of both the protein and the modification in splicing remains unclear. We demonstrated that inactivation of the METTL4 gene in HeLa S3 cells leads to significant changes in alternative splicing, general slowdown in spliceosome activity, and intron accumulation. In the cells lacking METTL4, expression of the set of genes associated with ribosomal RNA maturation is reduced, and the number of coilin-positive structures, most likely Cajal bodies, is decreased in the nuclei of these cells.

This study investigated permeability of the apical and basolateral membranes of rat corneal endothelial cells to water and urea. We demonstrated that the apparent water permeability of the basolateral membrane of endothelial cells (4.43E−05 ± 7.57E−07 cm/s) is more than three times higher than that of the apical membrane (1.21E−05 ± 1.03E−07 cm/s). Permeability of the basolateral membrane to urea (1.23E−04 ± 1.56E−06 cm/s) was statistically significantly higher than that of the apical membrane (9.52E−05 ± 1.02E−06 cm/s) by approximately 30%. We examined contribution of the phloretin-inhibited urea transport across the apical and basolateral membranes in these cells. Phloretin at concentration of 0.1 mM significantly reduced urea permeability by more than 20% through both the apical and basolateral membranes. The results suggest that the compositions of transporters involved in water transport in the apical and basolateral membranes differ significantly. It is hypothesized that high apparent water permeability of the basolateral membrane of endothelial cells is due to contribution of the concomitant water transport with ions involved in active transport processes. Presence of the phloretin-sensitive urea transporters in the plasma membrane of endothelial cells, likely involved in its transcellular transport, has been demonstrated. The results indicate potential significance of urea for corneal function.

The SFPQ (Splicing Factor Proline and Glutamine rich) protein, initially identified as a splicing factor, is a multifunctional nuclear protein involved in various cellular processes. Its main cellular partner is NONO (Non-POU domain-containing octamer-binding protein), with which SFPQ forms a heterodimer that is a crucial component of subnuclear structures called paraspeckles and located near nuclear speckles. However, SFPQ can also function independently in certain cellular processes and is essential for cell viability. There is substantial evidence of the involvement of SFPQ in the repair of double-strand DNA breaks (DSBs), but a definitive understanding of the mechanism of its participation in this critical cellular process is still lacking. In this review, we aim to summarize and systematize the existing data on the role of SFPQ and its complex with NONO in the repair of double-strand DNA breaks.

The effect of the C-terminal tail on the bioactivity of Agaricus bisporus mannose-binding protein (Abmb) was investigated. Based on the earlier obtained crystal structure of Abmb, it was suggested that the additional C-terminal tail can modulate the binding of sugars to the protein. According to glycan microarray, Abmb can bind β-Gal sugars, which contradicted the results of SPR analysis showing that Abmb only interacts with α-Man and not with α-Gal. Here, we used MCF-7 and MDA-MB-231 breast cancer cells to demonstrate that the presence of the C-terminal tail decreased the anti-proliferative activity of Abmb. Pre-incubating Abmb with α-Gal did not eliminate the anti-proliferative activity, while pre-incubation with α-Man attenuated it. At the same time, preincubation with a mixture of α-Gal and α-Man strongly promoted the anti-proliferative activity of Abmb. In silico analysis using molecular docking suggested the presence of a second functional sugar-binding site for Gal, which had not been identified previously. The study provides new insights into the structure of lectins and their interaction with sugars

Tumor-associated fibroblasts (TAFs) are a key cellular component of solid tumors, including gliomas. They support the growth of malignant cells, stimulate their invasion and metastasis, induce chemoresistance, and suppress the antitumor immune response. TAFs are formed from resident stromal cells under the influence of tumor cell secretome, including growth factors, chemokines, and extracellular vesicles. Communication between malignant cells and TAFs occurs through direct cell–cell contacts and exchange of secreted molecules and membrane vesicles. In this work, apoptotic bodies (apoBDs) were obtained from two types of glioma cells (T98g cell line and Gbl25 cells isolated from a glioblastoma biopsy) and characterized for surface markers. The surface of tumor apoBDs contained glioblastoma tumor-associated markers, such as GD2 ganglioside and A2B5 antigen. Glioma apoBDs contained lower levels of “don’t eat me” molecules and higher levels of “eat me” molecules compared to the original intact glioma cells. On one hand, glioma apoBDs reduced the viability of normal dermal fibroblasts in a dose-dependent manner; on the other hand, they initiated their transformation into the inflammatory subtype of TAFs (iTAFs). iTAFs obtained in this way demonstrated upregulated transcription of genes encoding cytokines, chemokines, and growth factors (IL17A, IL18, IL33, IFN-γ, CCL3, CCL5, CXCL1, CXCL5, CXCL10, CXCL12, TGFB1, and TNF) responsible for maintaining both tumorigenesis itself and the ability of fibroblasts to support it. It was found that glioma apoBDs were able to transfer tumor-associated markers (GD2 ganglioside and A2B5 antigen) to normal fibroblasts. The assessment of the effects of anti-GD2 antibody–drug conjugates (ADCs) on TAFs suggests the possibility of development of targeted drugs effective not only against tumor cells but also against tumor stroma.

Ferroptosis is an iron-dependent form of regulated cell death induced by hyperoxidation of polyunsaturated fatty acids (PUFAs) in cytoplasmic membrane phospholipids. Recent research has identified four key regulatory pathways of this process, with glutathione pathway (SLC7A11/SLC3A2)/GSH/GPX4 being the most central and well-studied. Functioning of all ferroptosis control systems is supported by the multilevel network of protein-coding and regulatory genes, whose dysregulated expression could trigger tumor cell transformation. Ferroptosis, alongside with other types of programmed cell death, plays a pivotal role in pathogenesis of many cancers, including non-small cell lung cancer (NSCLC). This review provides a comprehensive overview of the molecular mechanisms of ferroptosis and summarizes experimental evidence demonstrating involvement of the ferroptosis-associated non-coding RNAs (microRNAs and long non-coding RNAs) in the development and progression of NSCLC. Special emphasis is placed on the potential application of anti-ferroptotic and pro-ferroptotic non-coding RNAs in NSCLC therapy, focusing on targeted modulation of their expression to induce ferroptosis in tumor cells.