Biologičeskie membrany

Currently, foreign DNA or RNA sensor proteins, which play an important role in innate immunity, are of great interest as a new avenue for cancer immunotherapy. Agonists of these proteins can activate signaling cascades in immune cells that cause the production of cytokines, in particular type I interferons, which have a powerful cytotoxic effect. This review examines the functioning of cytoplasmic nucleic acid sensors such as cGAS, STING, IFI16, AIM2, DAI, DDX41, DNA-PK, MRE-11, and TREX1 involved in activating the production of various cytokines.

In vertebrate genomes, three genes encode subunits of IP₃ receptors, including IP₃R1, IP3R2, and IP₃R3. Despite high homology between different subunits, homotetrameric IP₃ receptors formed by IP₃R1, IP₃R2, and IP₃R3 in the endoplasmic reticulum membrane are markedly distinct by their functional features and regulatory mechanisms. It was particularly reported that IP₃R1 is specifically regulated by the IP₃R binding protein released with IP₃ (IRBIT), which competes with IP₃ for binding to IP₃R1. In turn, affinity of IRBIT/IP₃R1 binding is regulated by phosphorylation of IRBIT. By using the CRISPR/Cas9 approach to edit the genome of HEK-293 cells, two monoclonal cell lines were generated as a platform for uncovering a role of IRBIT and associated regulatory circuits in control of the IP₃R1 activity. In one line, HEK-IP₃R1, IP₃R2, and IP₃R3 genes were disrupted, while IP₃R1 was remained functional. Based on this line, the HEK-IP₃R1/DIRBIT line was generated, wherein IRBIT (AHCYL1) gene was inactivated. The comparative analysis of ACh-induced Ca²⁺ signaling in cells of both lines was performed by employing the Ca²⁺ dye Fluo-4 and Ca²⁺ imaging. It was particularly shown that ACh mobilized Ca²⁺ in cells of both lines, which responded to the agonist at widely varied doses in an “all-or-nothing” manner. Yet, HEK-IP₃R1/DIRBIT cells turned out to be less sensitive to ACh compared to HEK-IP₃R1 cells.

Norepinephrine (NE), which is released by sympathetic nerve endings, causes an increase in the frequency of spontaneous action potentials in the pacemaker cardiomyocytes of the sinoatrial node (SAN), also known as the “pacemaker” of the heart. This results in an increase in heart rate (HR). It is known that two types of postsynaptic adrenoreceptors (ARs), α1-AR and β-AR, can mediate the effects of NE. The role of α1-AR in the sympathetic control of heart rate and SAN automaticity, as well as the membrane mechanisms mediation the effects of α1-AR on the pacemaker, have not yet been elucidated. In this study, we utilized immunofluorescence confocal microscopy to examine the distribution of α1A-AR in the SAN of rats. Additionally, we assessed the expression of α1A-AR mRNA in the SAN tissue using RT-PCR. Furthermore, we investigated the impact of α1-AR stimulation on key functional parameters of the pacemaker, including the corrected sinus node recovery time (SNRT/cSNRT) and the SAN accommodation, using the Langendorff perfused heart technique. We also used optical mapping of the electrical activity of perfused, isolated tissue preparations to study the effect of α1-AR stimulation on the spatiotemporal characteristics of SAN excitation. We tested the effects of chloride transmembrane conductance blockade on alteration of functional parameters and pattern of SAN excitation caused by α1-AR. Fluorescent signals corresponding to α1A-AR have been identified in SAN cardiomyocytes, indicating the presence of α1A-AR at protein level. The expression of α1A-AR in SAN has been also confirmed at the mRNA level. The stimulation of α1-AR affects SAN functioning Phenylephrine (PHE) utilized as α1A-AR agonist causes a decrease in SNRT/cSNRT, as well as an acceleration of SAN accommodation. These effects were rate dependent and were observed at a high frequency of pacemaker tissue stimulation. PHE induces changes in the excitation pattern of the SAN. The effects of PHE on functional parameters and SAN excitation pattern are attenuated by Ca2+-dependent chloride channel blocker NPPB but remains unaffected by the protein kinase C inhibitor BIM. Our results suggest that cardiac α1-ARs are important for maintaining function of SAN pacemaker at high heart rates and that α1-AR signalling cascades in the SAN target Ca2+-dependent chloride channels are involved in the α1-adrenergic modulation of the electrophysiological properties of the heart pacemaker.

In this work, the properties of gel materials based on collagen and derivatives of taxifolin, pentaglutarate of taxifolin, and conjugate of taxifolin with glyoxylic acid were studied. It was shown that the increase in the proportion of the polyphenols in a gel led to the decrease in the rate of degradation of the materials. The materials had no negative impact on the viability of NIH/3T3 cells. The cells attached to the surface of the materials. Moreover, it was shown that they spread to the surface of the material containing pentaglutarate of taxifolin. It was also found that fibroblast migrated throughout the materials. An increase in the proportion of conjugate of taxifolin with glyoxylic acid in a material led to a decrease in cell migration throughout the material, whereas an increase in the proportion of pentaglutarate of taxifolin in a material led to a significant increase in cell migration throughout the material. The obtained data suggest that new materials for regenerative medicine can be derived from collagen and taxifolin derivatives.