Publications by authors named "BESSONOV S"

Background: The prevalence of hepatitis C virus (HCV) among people who inject drugs (PWID) continues to be a major public-health burden in this highly stigmatised population. To halt transmission of HCV, rapid HCV self-testing kits represent an innovative approach that could enable PWID to know their HCV status and seek treatment. As no HCV test has yet been licenced for self-administration, it is crucial to obtain knowledge around the factors that may deter or foster delivery of HCV self-testing among PWID in resource-constrained countries.

View Article and Find Full Text PDF

Non-coding RNA from pericentromeric satellite repeats are involved in stress-dependent splicing processes, maintenance of heterochromatin, and are required to protect genome stability. Here we show that the long non-coding satellite III RNA (SatIII) generates resistance against the topoisomerase IIa (TOP2A) inhibitor etoposide in lung cancer. Because heat shock conditions (HS) protect cells against the toxicity of etoposide, and SatIII is significantly induced under HS, we hypothesized that the protective effect could be traced back to SatIII.

View Article and Find Full Text PDF

RNA-binding proteins (RBPs) perform key cellular activities by controlling the function of bound RNAs. The widely held assumption that RBPs are strictly intracellular has been challenged by the discovery of secreted RBPs. However, extracellular RBPs have been described in eukaryotes, while secreted bacterial RBPs have not been reported.

View Article and Find Full Text PDF

Aquarius is a multifunctional putative RNA helicase that binds precursor-mRNA introns at a defined position. Here we report the crystal structure of human Aquarius, revealing a central RNA helicase core and several unique accessory domains, including an ARM-repeat domain. We show that Aquarius is integrated into spliceosomes as part of a pentameric intron-binding complex (IBC) that, together with the ARM domain, cross-links to U2 snRNP proteins within activated spliceosomes; this suggests that the latter aid in positioning Aquarius on the intron.

View Article and Find Full Text PDF

The roles of Argonaute proteins in cytoplasmic microRNA and RNAi pathways are well established. However, their implication in small RNA-mediated transcriptional gene silencing in the mammalian cell nucleus is less understood. We have recently shown that intronic siRNAs cause chromatin modifications that inhibit RNA polymerase II elongation and modulate alternative splicing in an Argonaute-1 (AGO1)-dependent manner.

View Article and Find Full Text PDF

The spliceosome undergoes major changes in protein and RNA composition during pre-mRNA splicing. Knowing the proteins-and their respective quantities-at each spliceosomal assembly stage is critical for understanding the molecular mechanisms and regulation of splicing. Here, we applied three independent mass spectrometry (MS)-based approaches for quantification of these proteins: (1) metabolic labeling by SILAC, (2) chemical labeling by iTRAQ, and (3) label-free spectral count for quantification of the protein composition of the human spliceosomal precatalytic B and catalytic C complexes.

View Article and Find Full Text PDF

Serine/arginine-rich (SR) proteins are important players in RNA metabolism and are extensively phosphorylated at serine residues in RS repeats. Here, we show that phosphorylation switches the RS domain of the serine/arginine-rich splicing factor 1 from a fully disordered state to a partially rigidified arch-like structure. Nuclear magnetic resonance spectroscopy in combination with molecular dynamics simulations revealed that the conformational switch is restricted to RS repeats, critically depends on the phosphate charge state and strongly decreases the conformational entropy of RS domains.

View Article and Find Full Text PDF

Although U snRNAs play essential roles in splicing, little is known about the 3D arrangement of U2, U6, and U5 snRNAs and the pre-mRNA in active spliceosomes. To elucidate their relative spatial organization and dynamic rearrangement, we examined the RNA structure of affinity-purified, human spliceosomes before and after catalytic step 1 by chemical RNA structure probing. We found a stable 3-way junction of the U2/U6 snRNA duplex in active spliceosomes that persists minimally through step 1.

View Article and Find Full Text PDF

Unlabelled: Complexity of treatment of children for congenital bilateral clefts is caused by anatomical and functional impairments of the middle zone of the face present in it: splitting of the upper lip and alveolar process in 3 parts, protrusion of the intermaxillary bone, lack or hypoplasia of muscular fibers in the central portion of the lip, shortening of columella, flattering of the nose wings.

The Aim Of The Paper: improvement of the methods of surgical treatment of patients for congenital bilateral clefts of the upper lip to obtain higher esthetic and functional results. 62 infants aged 3-9 months with congenital bilateral clefts of the upper lip and associated nose deformation were operated.

View Article and Find Full Text PDF

More than 200 proteins associate with human spliceosomes, but little is known about their relative abundances in a given spliceosomal complex. Here we describe a novel two-dimensional (2D) electrophoresis method that allows separation of high-molecular-mass proteins without in-gel precipitation and thus without loss of protein. Using this system coupled with mass spectrometry, we identified 171 proteins altogether on 2D maps of stage-specific spliceosomal complexes.

View Article and Find Full Text PDF

The spliceosome excises introns from pre-mRNA in a two-step splicing reaction. So far, the three-dimensional (3D) structure of a spliceosome with preserved catalytic activity has remained elusive. Here, we determined the 3D structure of the human, catalytically active step I spliceosome (C complex) by cryo-electron microscopy (cryo-EM) in vitrified ice.

View Article and Find Full Text PDF

To better understand the compositional and structural dynamics of the human spliceosome during its activation, we set out to isolate spliceosomal complexes formed after precatalytic B but prior to catalytically active C complexes. By shortening the polypyrimidine tract of the PM5 pre-mRNA, which lacks a 3' splice site and 3' exon, we stalled spliceosome assembly at the activation stage. We subsequently affinity purified human B(act) complexes under the same conditions previously used to isolate B and C complexes, and analyzed their protein composition by mass spectrometry.

View Article and Find Full Text PDF

Study was performed of chondroblast proliferative activity peculiarities on early stages of big alar cartilage forming. The reaction with monoclonal antibodies towards proliferating cell nuclear antigen in alar cartilage of human embryo and newly born infant rat testified to 2 cartilage growth types - appositional and interstitial. Cells proliferative activity did not depend upon their location on inner or outer side of nasal cartilaginous plate thereby not conforming existent in the literature opinion about the presence of special zones of cartilaginous tissue primary new formation in human nasal cartilage on early stages of its ontogeny.

View Article and Find Full Text PDF

Formation of catalytically active RNA structures within the spliceosome requires the assistance of proteins. However, little is known about the number and nature of proteins needed to establish and maintain the spliceosome's active site. Here we affinity-purified human spliceosomal C complexes and show that they catalyse exon ligation in the absence of added factors.

View Article and Find Full Text PDF

In multiple myeloma (MM), both vascular endothelial (VEGF) and basic fibroblast growth factor (bFGF) promote tumor growth and survival. We have used the novel indolinone BIBF 1000 to study effects of simultaneous inhibition of VEGF, FGF and transforming growth factor-beta on MM cells and their interactions with bone marrow stroma cells (BMSCs). Both, in the absence and presence of myeloma-stroma cell contacts, BIBF 1000 abrogated BMSC-derived secretion of interleukin-6 (IL-6).

View Article and Find Full Text PDF

Philtrum (labial groove) has aesthetic importance and governs individual features of human face. There are discussed the ways of philtrum reconstruction described in domestic and foreign literature. The main principles of the upper lip central part formation in one-sided congenital clefts are set out.

View Article and Find Full Text PDF

Kinetics of photolysis of the antibiotic tetracycline (TC) during irradiation at 365 nm was studied in three buffer solutions usually used for studies on TC binding to its main cell targets--a transcriptional repressor protein TetR and to the ribosome. These buffer solutions contain magnesium ions and an antioxidant--mercaptoethanol or dithiothreitol. The rate of TC photolysis was maximal in medium which contained 14 mM mercaptoethanol and 5 mM magnesium ions.

View Article and Find Full Text PDF

Gnathometric and roentgenocephalometric studies helped reveal the pathogenesis of abnormal maxillary growth in children with bilateral clefts of the upper lip and palate. In order to improve the results of treatment of such patients, the authors propose a method of secondary early osteoplasty of the alveolar process, which may be carried out simultaneously with uranoplasty or separately. Thirty-six patients were operated on using this technique.

View Article and Find Full Text PDF

Anthropometric examinations of 31 patients with bilateral incomplete clefts of the upper lip revealed an excessive elongation of the lateral fragments and reduced height of the central part of cleft lip. Two methods of primary rhinocheiloplasty are suggested, depending on the degree of prolabium underdevelopment, both of them permitting levelling of the height of the fragments and repair of anatomically correct shape of the upper lip and nose. Preparation and connection of the stumps of the oral orbicular muscle during the operation are conductive to recovery of the function of the upper lip, which is confirmed by electromyography data.

View Article and Find Full Text PDF