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1.  Recombinant Influenza Vaccines  
Acta Naturae  2012;4(4):17-27.
This review covers the problems encountered in the construction and production of new recombinant influenza vaccines. New approaches to the development of influenza vaccines are investigated; they include reverse genetics methods, production of virus-like particles, and DNA- and viral vector-based vaccines. Such approaches as the delivery of foreign genes by DNA- and viral vector-based vaccines can preserve the native structure of antigens. Adenoviral vectors are a promising gene-delivery platform for a variety of genetic vaccines. Adenoviruses can efficiently penetrate the human organism through mucosal epithelium, thus providing long-term antigen persistence and induction of the innate immune response. This review provides an overview of the practicability of the production of new recombinant influenza cross-protective vaccines on the basis of adenoviral vectors expressing hemagglutinin genes of different influenza strains.
PMCID: PMC3548171  PMID: 23346377
Recombinant vaccine; influenza; immunization
2.  Epigenetics of Pluripotent Cells  
Acta Naturae  2012;4(4):28-46.
Pluripotency is maintained by a complex system that includes the genetic and epigenetic levels. Recent studies have shown that the genetic level (transcription factors, signal pathways, and microRNAs) closely interacts with the enzymes and other specific proteins that participate in the formation of the chromatin structure. The interaction between the two systems results in the unique chromatin state observed in pluripotent cells. In this review, the epigenetic features of embryonic stem cells and induced pluripotent stem cells are considered. Special attention is paid to the interplay of the transcription factors OCT4, SOX2, and NANOG with the Polycomb group proteins and other molecules involved in the regulation of the chromatin structure. The participation of the transcription factors of the pluripotency system in the inactivation of the X chromosome is discussed. In addition, the epigenetic events taking place during reprogramming of somatic cells to the pluripotent state and the problem of “epigenetic memory” are considered.
PMCID: PMC3548172  PMID: 23346378
embryonic stem cells; induced pluripotent stem cells; pluripotency; covalent histone modifications; DNA methylation
3.  Effect of 3D Cultivation Conditions on the Differentiation of Endodermal Cells  
Acta Naturae  2012;4(4):47-57.
Cellular therapy of endodermal organs is one of the most important issues in modern cellular biology and biotechnology. One of the most promising directions in this field is the study of the transdifferentiation abilities of cells within the same germ layer. A method for anin vitroinvestigation of the cell differentiation potential (the cell culture in a three-dimensional matrix) is described in this article. Cell cultures of postnatal salivary gland cells and postnatal liver progenitor cells were obtained; their comparative analysis under 2D and 3D cultivation conditions was carried out. Both cell types have high proliferative abilities and can be cultivated for more than 20 passages. Under 2D cultivation conditions, the cells remain in an undifferentiated state. Under 3D conditions, they undergo differentiation, which was confirmed by a lower cell proliferation and by an increase in the differentiation marker expression. Salivary gland cells can undergo hepatic and pancreatic differentiation under 3D cultivation conditions. Liver progenitor cells also acquire a pancreatic differentiation capability under conditions of 3D cultivation. Thus, postnatal salivary gland cells exhibit a considerable differentiation potential within the endodermal germ layer and can be used as a promising source of endodermal cells for the cellular therapy of liver pathologies. Cultivation of cells under 3D conditions is a useful model for thein vitroanalysis of the cell differentiation potential.
PMCID: PMC3548173  PMID: 23346379
3D conditions; collagen gel; differentiation; endoderm; submandibular salivary gland cells; liver progenitor cells
4.  N-Terminal Fusion Tags for Effective Production of G-Protein-Coupled Receptors in Bacterial Cell-Free Systems  
Acta Naturae  2012;4(4):58-64.
G-protein-coupled receptors (GPCR) constitute one of the biggest families of membrane proteins. In spite of the fact that they are highly relevant to pharmacy, they have remained poorly explored. One of the main bottlenecks encountered in structural-functional studies of GPCRs is the difficulty to produce sufficient amounts of the proteins. Cell-free systems based on bacterial extracts fromE. colicells attract much attention as an effective tool for recombinant production of membrane proteins. GPCR production in bacterial cell-free expression systems is often inefficient because of the problems associated with the low efficiency of the translation initiation process. This problem could be resolved if GPCRs were expressed in the form of hybrid proteins with N-terminal polypeptide fusion tags. In the present work, three new N-terminal fusion tags are proposed for cell-free production of the human β2-adrenergic receptor, human M1 muscarinic acetylcholine receptor, and human somatostatin receptor type 5. It is demonstrated that the application of an N-terminal fragment (6 a.a.) of bacteriorhodopsin fromExiguobacterium sibiricum(ESR-tag), N-terminal fragment (16 а.о.) of RNAse A (S-tag), and Mistic protein fromB. subtilisallows to increase the CF synthesis of the target GPCRs by 5–38 times, resulting in yields of 0.6–3.8 mg from 1 ml of the reaction mixture, which is sufficient for structural-functional studies.
PMCID: PMC3548174  PMID: 23346380
Cell-free expression; GPCR; translation initiation
5.  Identification of Novel RNA-Protein Contact in Complex of Ribosomal Protein S7 and 3’-Terminal Fragment of 16S rRNA in E. coli  
Acta Naturae  2012;4(4):65-72.
For prokaryotes in vitro, 16S rRNA and 20 ribosomal proteins are capable of hierarchical self- assembly yielding a 30S ribosomal subunit. The self-assembly is initiated by interactions between 16S rRNA and three key ribosomal proteins: S4, S8, and S7. These proteins also have a regulatory function in the translation of their polycistronic operons recognizing a specific region of mRNA. Therefore, studying the RNA–protein interactions within binary complexes is obligatory for understanding ribosome biogenesis. The non-conventional RNA–protein contact within the binary complex of recombinant ribosomal protein S7 and its 16S rRNA binding site (236 nucleotides) was identified. UV–induced RNA–protein cross-links revealed that S7 cross-links to nucleotide U1321 of 16S rRNA. The careful consideration of the published RNA– protein cross-links for protein S7 within the 30S subunit and their correlation with the X-ray data for the 30S subunit have been performed. The RNA – protein cross–link within the binary complex identified in this study is not the same as the previously found cross-links for a subunit both in a solution, and in acrystal. The structure of the binary RNA–protein complex formed at the initial steps of self-assembly of the small subunit appears to be rearranged during the formation of the final structure of the subunit.
PMCID: PMC3548175  PMID: 23346381
ribosome; initiation; self-assembly; ribosomal protein S7; UV– induced cross-linking
6.  Gold Nanoparticle Clusters in Quasinematic Layers of Liquid-Crystalline Dispersion Particles of Double-Stranded Nucleic Acids  
Acta Naturae  2012;4(4):78-90.
The interaction between gold nanoparticles and particles of cholesteric liquid-crystalline dispersions formed by double-stranded DNA and poly(I)×poly(C) molecules is considered. It is shown that small-sized (~ 2 nm) gold nanoparticles induce two different structural processes. First, they facilitate the reorganization of the spatial cholesteric structure of the particles into a nematic one. This process is accompanied by a fast decrease in the amplitude of an abnormal band in the CD spectrum. Second, they induce cluster formation in a “free space” between neighboring nucleic acid molecules fixed in the structure of the quasinematic layers of liquid-crystalline particles. This process is accompanied by slow development of the surface plasmon resonance band in the visible region of the absorption spectrum. Various factors influencing these processes are outlined. Some assumptions concerning the possible mechanism(s) of fixation of gold nanoparticles between the neighboring double-stranded nucleic acid molecules in quasinematic layers are formulated.
PMCID: PMC3548176  PMID: 23346383
DNA; poly(I)×poly(C); liquid-crystalline dispersions of nucleic acids; gold nanoparticles; circular dichroism; absorption spectroscopy; abnormal optical activity; surface plasmon resonance; structure of biopolymer lyotropic liquid crystals; cytotoxicity of nanoparticles
7.  Methanogenic Community Dynamics during Anaerobic Utilization of Agricultural Wastes  
Acta Naturae  2012;4(4):91-97.
This work is devoted to the investigation of the methanogenic archaea involved in anaerobic digestion of cattle manure and maize straw on the basis of terminal restriction fragment length polymorphism (T-RFLP) analysis of archaeal 16S rRNA genes. The biological diversity and dynamics of methanogenic communities leading to anaerobic degradation of agricultural organic wastes with biogas production were evaluated in laboratory-scale digesters. T-RFLP analysis, along with the establishment of archaeal 16S rRNA gene clone libraries, showed that the methanogenic consortium consisted mainly of members of the generaMethanosarcinaandMethanoculleus,with a predominance ofMethanosarcinaspp. throughout the experiment.
PMCID: PMC3548177  PMID: 23346384
8.  Carbocyclic Analogues of Inosine-5’-Monophosphate: Synthesis and Biological Activity  
Acta Naturae  2012;4(4):73-77.
9-(4’-Phosphonomethoxy-2’-cyclopenten-1’-yl)hypoxanthine and 9-(4’-phosphonomethoxy-2’,3’-dihydroxycyclopenten-1’-yl)hypoxanthine were synthesized as isosteric carbocyclic analogues of inosine-5’-monophosphate. The synthesized compounds were shown to be capable of inhibiting the activity of human type II inosine-5′-monophosphate dehydrogenase (IMPDH II) (IC50 = 500 µM) and to have no significant effects on the growth ofMycobacterium tuberculosis.
PMCID: PMC3549521  PMID: 23346382
Carbocyclic nucleosides; competitive inhibition; inosine-5’-monophosphate; human IMPDH II,Mycobacterium tuberculosis
9.  The Use of Cellular Technologies in Treatment of Liver Pathologies 
Acta Naturae  2012;4(3):16-30.
Cell techniques find increasing application in modern clinical practice. The II and III phases of clinical trials are already under way for various cellular products used for the restoration of the functions of the cornea, larynx, skin, etc. However, the obtainment of functional cell types specific to different organs and tissues still remains a subject of laboratory research. Liver is one of the most important organs; the problems and prospects of cellular therapy for liver pathologies are currently being actively studied. Cellular therapy of liver pathologies is a complex multistage process requiring a thorough understanding of the molecular mechanisms occurring in liver cells during differentiation and regeneration. An analysis of the current cellular therapy for liver pathologies is presented, the use of various cell types is described, the main molecular mechanisms of hepatocyte differentiation are analyzed, and the challenges and prospects of cell therapy for liver disorders are discussed in this review.
PMCID: PMC3491890  PMID: 23150801
cell transplantation; cellular therapy; differentiation; liver
10.  Receptor Properties and Features of Cytokinin Signaling 
Acta Naturae  2012;4(3):31-45.
Cytokinins belong to one of the most important and well-known classes of plant hormones. Discovered over half a century ago, cytokinins have retained the attention of researchers due to the variety of the effects they have on the growth and development of vegetable organisms, their participation in a plant adaptation to external conditions, and the potential to be used in biotechnology, agriculture, medicine and even cosmetics. The molecular mechanism by which cytokinins function remained unknown for a long time. Things started to change only in the 21stcentury, after the discovery of the receptors for these phytohormones. It appeared that plants found ways to adapt a two-component signal transduction system borrowed from prokaryotic organisms for cytokinin signalling. This review covers the recent advances in research of the molecular basis for the perception and transduction of the cytokinin signal. Emphasis is placed on cytokinin receptors, their domain and three-dimensional structures, subcellular localization, signalling activity, effect of mutations, ligand-binding properties, and phylogeny.
PMCID: PMC3491891  PMID: 23150802
cytokinins; receptors; sensor histidine kinases; two-component systems; signal transduction
11.  A Polygenic Approach to the Study 
of Polygenic Diseases 
Acta Naturae  2012;4(3):59-71.
Polygenic diseases are caused by the joint contribution of a number of independently acting or interacting polymorphic genes; the individual contribution of each gene may be small or even unnoticeable. The carriage of certain combinations of genes can determine the occurrence of clinically heterogeneous forms of the disease and treatment efficacy. This review describes the approaches used in a polygenic analysis of data in medical genomics, in particular, pharmacogenomics, aimed at identifying the cumulative effect of genes. This effect may result from the summation of gains of different genes or be caused by the epistatic interaction between the genes. Both cases are undoubtedly of great interest in investigating the nature of polygenic diseases. The means that allow one to discriminate between these two possibilities are discussed. The methods for searching for combinations of alleles of different genes associated with the polygenic phenotypic traits of the disease, as well as the methods for presenting and validating the results, are described and compared. An attempt is made to evaluate the applicability of the existing methods to an epistasis analysis. The results obtained by the authors using the APSampler software are described and summarized.
PMCID: PMC3491892  PMID: 23150804
medical genomics; pharmacogenomics; polygenic analysis; epistasis
12.  Cardiological Biopharmaceuticals in the Conception of Drug Targeting Delivery: Practical Results and Research Perspectives 
Acta Naturae  2012;4(3):72-81.
The results of the clinical use of thrombolytic and antithrombotic preparations developed on the basis of protein conjugates obtained within the framework of the conception of drug targeting delivery in the organism are considered. A decrease has been noted in the number of biomedical projects focused on these derivatives as a result of various factors: the significant depletion of financial and organizational funds, the saturation of the pharmaceutical market with preparations of this kind, and the appearance of original means for interventional procedures. Factors that actively facilitate the conspicuous potentiation of the efficacy of bioconjugates were revealed: the biomedical testing of protein domains and their selected combinations, the optimization of molecular sizes for the bioconjugates obtained, the density of target localization, the application of cell adhesion molecules as targets, and the application of connected enzyme activities. Enzyme antioxidants and the opportunity for further elaboration of the drug delivery conception via the elucidation and formation of therapeutic targets for effective drug reactions by means of pharmacological pre- and postconditioning of myocardium arouse significant interest.
PMCID: PMC3491893  PMID: 23150805
drug targeting delivery; protein bioconjugates; thrombolytics; antithrombotic agents; molecular size of bioconjugates; density of molecular targets; enzyme connected antioxidants; cell adhesion molecules; pharmacological pre- and post-conditioning of myocardium
13.  Non-thermal Plasma Causes p53-Dependent Apoptosis in Human Colon Carcinoma Cells 
Acta Naturae  2012;4(3):82-87.
Non-thermal plasma (NTP) consists of a huge amount of biologically active particles, whereas its temperature is close to ambient. This combination allows one to use NTP as a perspective tool for solving different biomedical tasks, including antitumor therapy. The treatment of tumor cells with NTP caused dose-dependent effects, such as growth arrest and apoptosis. However, while the outcome of NTP treatment has been established, the molecular mechanisms of the interaction between NTP and eukaryotic cells have not been thoroughly studied thus far. In this work, the mechanisms and the type of death of human colon carcinoma HCT 116 cells upon application of non-thermal argon plasma were studied. The effect of NTP on the major stress-activated protein p53 was investigated. The results demonstrate that the viability of HCT116 cells upon plasma treatment is dependent on the functional p53 protein. NTP treatment caused an increase in the intracellular concentration of p53 and the induction of the p53-controlled regulon. The p53-dependent accumulation of active proapoptotic caspase-3 was shown in NTP-treated cells. The study was the first to demonstrate that treatment of human colon carcinoma cells with NTP results in p53-dependent apoptosis. The results obtained contribute to our understanding of the applicability of NTP in antitumor therapy.
PMCID: PMC3491894  PMID: 23150806
non-thermal plasma; protein p53; apoptosis
14.  Mitochondrial Pathway of α-Tocopheryl Succinate-Induced Apoptosis in Human Epidermoid Carcinoma A431 Cells 
Acta Naturae  2012;4(3):88-94.
Vitamin E derivatives are known to act as agents exhibiting cytotoxity against tumor cells. The effect of vitamin E succinate on human epidermoid carcinoma cell line A431 was investigated in this study using live imaging, immunocytochemistry, and transmission electron microscopy. α-Tocopheryl succinate-induced apoptotic cell death in A431 cells was shown to be both dose- and time-dependent. The hyperproduction of reactive oxygen species, changes in size, shape and ultrastructural characteristics of mitochondria followed by the release of cytochromecfrom mitochondria to cytosol were observed. These results suggest that α-tocopheryl succinate induces apoptosis that occurs via the mitochondrial pathway. Mitochondria are shown to be crucial targets in α-tocopheryl succinate-induced caspase-dependent cell death in human carcinoma A431 cells.
PMCID: PMC3491895  PMID: 23150807
α-tocopheryl succinate; apoptosis; mitochondrial pathway; ROS; cytochromec
15.  Gene Expression upon Proliferation and Differentiation of Hematopoietic Cells with Ph Chromosome ex vivo 
Acta Naturae  2012;4(3):95-114.
The genesp53, mdm2, p21, c-myc,bcr/abl, bcr, bcl2, bax, and gapdh participate in the regulation of cell proliferation and differentiation, apoptosis and cell distribution for the cell cycle ex vivo in the Ph+cells of chronic myeloid leukemia containing the Ph chromosome andbcr/abloncogene. Expression of these genes correlates with regulation of cell proliferation and differentiation by alternating proliferation and maturation stages for three main Ph+cell types that occur under chronic myeloid leukemia. Thep53, p21, mdm2, and gapdh genes overexpress in active proliferating myeloid cells in the cell cycle S+ G2/M phases and when the phases are coincident with the proliferation stage. Expression of these genes decreases to a considerable level under alternation of the Ph+cell proliferation and maturation stages and whenever the expression is greatly diminished under significant neutrophil accumulation and especially under repeated alternation of the stages. In the course of neutrophil maturation, gene expression levels decrease in the range of gapdh > actin > c-myc, bcr/abl,p21 > p53 > bcl2 > bax.The expression levels of these genes in neutrophils are lower than those in myelocytes and lower by an order of magnitude than that in the cells with a prolonged proliferation stage. TheBcr/ablexpression gene under prolonged maturation and neutrophil accumulation is inhibited; however it is enhanced by 2–3 times for the proliferation stage with myelocyte accumulation. Minimalbcr/ablexpression is observed under overexpression ofp53, mdm2, p21, c-myc,as well as under cell maximum at the S and G2/M phases. Bcr/abloverexpression is observed under low expression of thep53, p21, mdm2genes. In the Ph+ cells with a high P/D efficiency index (5–20), overexpression of the genes in the range ofbcr> gapdh>bcr/abl, as well as a decreased expression of thep53, bcl2, mdm2, p21<< gapdh genes is observed for Ph+cells from the CML blast crisis and CML acceleration phase. Low control of cell proliferation and cell cycle by gene-regulators presumably promotesbcr/abloverexpression and activаtes the production ofbcr/abl+ cells. Apoptosis in the Ph+ cells is induced by expression of thebax > bcl2, р53, p21, c-myc andgapdhgenes. The blocking of Ph+cell apoptosis, neutrophil accumulation, and decrease in the expression of the p53, mdm2 and p21, c-myc,bcr/abl genes occur at the maturation stage.
PMCID: PMC3491896  PMID: 23150808
gene expression; regulation of cell proliferation and differentiation; cells containing Ph chromosome; chronic myeloid leukemia; RT-PCR, cell cycle; apoptosis
16.  Lipopolysaccharide of Yersinia pestis, the Cause of Plague: Structure, Genetics, Biological Properties 
Acta Naturae  2012;4(3):46-58.
The present review summarizes data pertaining to the composition and structure of the carbohydrate moiety (core oligosaccharide) and lipid component (lipid A) of the various forms of lipopolysaccharide (LPS), one of the major pathogenicity factors ofYersinia pestis, the cause of plague. The review addresses the functions and the biological significance of genes for the biosynthesis of LPS, as well as the biological properties of LPS in strains from various intraspecies groups ofY. pestis and their mutants, including the contribution of LPS to the resistance of bacteria to factors of the innate immunity of both insect-vectors and mammal-hosts. Special attention is paid to temperature-dependent variations in the LPS structure, their genetic control and roles in the pathogenesis of plague. The evolutionary aspect is considered based on a comparison of the structure and genetics of the LPS ofY. pestis and other enteric bacteria, including otherYersinia species. The prospects of development of live plague vaccines created on the basis ofY. pestis strains with the genetically modified LPS are discussed.
PMCID: PMC3492934  PMID: 23150803
lipopolysaccharide; lipid A; plague; Yersinia pestis; immune response; antibiotic resistance
17.  Physicochemical Biology: Conquered Boundaries and New Horizons
 
Acta Naturae  2012;4(2):36-43.
In this paper, we shall consider the main evolutionary stages that occurred within the field of physicochemical biology during the 20th century, following the determination of the tertiary structure of DNA by Watson and Crick and the subsequent successes in the X-ray structural analysis of biopolymers. The authors’ ideas on the pre-emptive problems and the methods used in physicochemical biology in the 21st century are also presented, including an investigation of the dynamics of biochemical processes, studies of the functions of unstructured proteins, as well as single-molecule investigations of enzymatic processes and of biopolymer tertiary structure formation.
PMCID: PMC3408702  PMID: 22872810
DNA structure; enzyme active sites; unstructured proteins; dynamics of biochemical processes; single molecule studies of enzymatic processes and biopolymer tertiary structure formation
18.  Telomere Lengthening and Other Functions of Telomerase
 
Acta Naturae  2012;4(2):44-61.
Telomerase is an enzyme that maintains the length of the telomere. The telomere length specifies the number of divisions a cell can undergo before it finally dies (i.e. the proliferative potential of cells). For example, telomerase is activated in embryonic cell lines and the telomere length is maintained at a constant level; therefore, these cells have an unlimited fission potential. Stem cells are characterized by a lower telomerase activity, which enables only partial compensation for the shortening of telomeres. Somatic cells are usually characterized by the absence of telomerase activity. Telomere shortening leads to the attainment of the Hayflick limit, the transition of cells to a state of senescence. The cells subsequently enter a state of crisis, accompanied by massive cell death. The surviving cells become cancer cells, which are capable both of dividing indefinitely and maintaining telomere length (usually with the aid of telomerase). Telomerase is a reverse transcriptase. It consists of two major components: telomerase RNA (TER) and reverse transcriptase (TERT). TER is a non-coding RNA, and it contains the region which serves as a template for telomere synthesis. An increasing number of articles focussing on the alternative functions of telomerase components have recently started appearing. The present review summarizes data on the structure, biogenesis, and functions of telomerase.
PMCID: PMC3408703  PMID: 22872811
telomerase; reverse transcriptase; telomeres; mitochondria; DNA damage; gene expression
19.  Coagulation Factor IX for Hemophilia B Therapy
 
Acta Naturae  2012;4(2):62-73.
Factor IX is a zymogen enzyme of the blood coagulation cascade. Inherited absence or deficit of the IX functional factor causes bleeding disorder hemophilia B, which requires constant protein replacement therapy. Reviewed herein are the current state in the manufacturing of FIX, improved variants of the recombinant protein for therapy, transgenic organisms for obtaining FIX, and the advances in the gene therapy of hemophilia B.
PMCID: PMC3408704  PMID: 22872812
сoagulation factor IX; hemophilia B; heterologous protein expression systems
20.  Contribution of the TGFB1 Gene 
to Myocardial Infarction Susceptibility
 
Acta Naturae  2012;4(2):74-79.
Carriage frequencies of alleles and genotypes of theTGFB1 gene polymorphous loci –509C>T (rs1800469), 869T>C (rs1982073), 915G>C (rs1800471), which affect the level of cytokine TGF-β1 production, were analyzed in the patients of Russian ethnic descent with myocardial infarction (MI) (406 cases) and in the control group of the same ethnic descent (198 controls). Significant association with MI was observed in carriage frequencies of the alleleTGFB1*–509T (p=0.046, OR =1.45, 95% CI: 1.02-2.06), genotypes TGFB1*869T/T (p=0.0024, OR =1.75, 95% CI: 1.22-2.51), andTGFB1*915G/G (p=0.048, OR=1.76, 95% CI: 1.05-2.97). Linkage disequilibrium analysis for these SNPs has shown that the associations revealed can be considered to be independent. A complex analysis of MI association with combinations of alleles/genotypes of said SNPs indicates their cumulative effect. An analysis of susceptibility to early-onset MI (≤ 50 years old) revealed a positive association of the alleleTGFB1*–509T (p=0.002, OR=2.24, 95% CI: 1.35-3.71) and genotypeTGFB1*869T/T (p=0.008, OR=1.93, 95% CI: 1.18-3.15), as well as their additivity. An analysis of susceptibility to recurrent MI revealed an association of the genotypeTGFB1*–509T/T (p=0.0078, OR=2.60, 95% CI: 1.28-5.28). The results obtained indicate the important role of theTGFB1gene in susceptibility to MI, including early-onset and recurrent MI, in Russians.
PMCID: PMC3408705  PMID: 22872813
myocardial infarction; Russians; genes; allelic polymorphism; transforming growth factor β1;TGFB1; APSampler
21.  Construction of a Full-Atomic Mechanistic Model of Human Apurinic/Apyrimidinic Endonuclease APE1 for Virtual Screening of Novel Inhibitors
 
Acta Naturae  2012;4(2):80-86.
A full-atomic molecular model of human apurinic/apyrimidinic endonuclease APE1, an important enzyme in the DNA repair system, has been constructed. The research consisted of hybrid quantum mechanics/molecular mechanics modeling of the enzyme-substrate interactions, as well as calculations of the ionization states of the amino acid residues of the active site of the enzyme. The choice of the APE1 mechanism with an Asp210 residue as a proton acceptor was validated by means of a generalization of modeling and experimental data. Interactions were revealed in the active site that are of greatest significance for binding the substrate and potential APE1 inhibitors (potential co-drugs of interest in the chemo- and radiotherapy of oncological diseases).
PMCID: PMC3408706  PMID: 22872814
apurinic/apyrimidinic endonuclease; QM/MM; enzymatic mechanism; molecular modeling; inhibition
22.  Recombinant Human Cyclophilin A in vitro Inhibits the Formation of Fibrin Clot
 
Acta Naturae  2012;4(2):98-101.
The chemotactic properties of cyclophilin A are well-known. There exists however a poor level of understanding regarding the hemostatic effects of this protein. Herein it is shown that recombinant human cyclophilin A (rhСyA), in contrast to the granulocyte colony-stimulating factor, is capable of inhibitingin vitrothe formation of a fibrin clot, thereby violating the spatial dynamics of clot growth; this effect is transient and dose-independent. Furthermore, the hypothesis that the conformational changes in the thrombin–rhCyA complex may mediate the anticoagulant effect of rhCyA on the autowave processes of blood clotting is postulated.
PMCID: PMC3408707  PMID: 22880163
recombinant human cyclophilin A; spatial dynamics of clot growth; anticoagulant activity
23.  Development of Chlamydial Type III Secretion System Inhibitors for Suppression of Acute and Chronic Forms of Chlamydial Infection
 
Acta Naturae  2012;4(2):87-97.
The Type III secretion system (T3SS) is currently considered to be one of the main pathogenicity factors in Gram-negative bacteria, which exhibit different types of parasitizing activity. The presence of this structure is essential for the development of an acute infection; the chronicity of the infection is fundamentally dependent upon its functioning. In this regard, T3TS is one of the most promising targets for the development of broad-spectrum antimicrobial drugs that do not develop resistance and are efficacious for the acute and chronic forms of infection. The mechanism of action in drug development is based on the specific inhibition of T3SS, which should interrupt the infectious process, thereby enabling the immune system to eliminate the pathogen. As a result of pilot screening using specific cellular and bacterial tests, followed by chemical optimization and detailed characterization of the biological activity, a new class of chlamydial T3SS inhibitors was obtained. The selected compounds have obvious advantages over the currently available inhibitors of T3SS pathogens thanks to the high inhibitory activity of these compounds with minimal damaging effects on eukaryotic cells. Preclinical trials of the selected inhibitors are currently under way.
PMCID: PMC3411183  PMID: 22880162
thiohydrazones; thiohydrazides; thiadiazines; type III secretion system; citotoxicity; Chlamydia; inhibitors; microscopy; electron microscopy; morphology
24.  Risk of HIV Infection and Lethality Are Decreased in CCR5del32  Heterozygotes: Focus Nosocomial Infection Study and Meta-analysis 
Acta Naturae  2012;4(1):42-52.
CCR5del32 Homozygous deletion in the chemokine receptor R5 gene provides almost complete protection to individuals against HIV infection. However, data relating to the protective effect forCCR5del32 heterozygous individuals have been contradictory. The frequency of theCCR5del32allele in population control cohorts was compared with that of a group of children (27 Kalmyks and 50 Russians) infected by G-subtype HIV-1 in a nosocomial outbreak. The frequency of theCCR5del32allele was shown to be lower among the infected children in comparison with that of the control group; however, the difference was small and statistically insignificant. Similar results were obtained in a number of earlier studies. The insignificance of the small differences could be a result of one of two reasons. (i) The fact that there is no protective effect of the heterozygous state, and that the phenomenon depends only on the fluctuation of allele frequencies. In this case, there would be no differences even if the infected cohort is enlarged. (ii)The protective effect of the heterozygous state is real; however, the size of the studied cohort is insufficient to demonstrate it. In order to discern between these two reasons, a meta-analysis of data from 25 published articles (a total of 5,963 HIV-infected individuals and 5,048 individuals in the control group, including the authors’ own data) was undertaken. A conclusion was drawn from the meta-analysis that theCCR5del32 allele protects individuals against the HIV infection even in a heterozygous state (OR=1.22, 95%CI=1.10–1.36). The risk of HIV infection forCCR5 wt/del32 heterozygotes was lower by at least 13% as compared to that for wild typeCCR5 wt/wthomozygotes. Prior to this study, no data of the type or any conclusions had been published for Caucasians. The mortality rate in the 15 years following the infection was found to be approximately 40% lower forCCR5del32 heterozygotes in comparison with that for the wild type homozygotes in the studied group. The size of the studied group was insufficient to claim difference validity (OR=2.0;p= 0.705), even though the effect quantitatively matched the published data. The features of the meta-analysis influencing the threshold level and the statistical validity of the effects are being discussed. The level of theCCR5del32 protective effect on the chances to be infected with HIV and on the outcome of the HIV infection was assessed for various ethnic groups.
PMCID: PMC3372986  PMID: 22708062
HIV; nosocomial infection; lethality risk; infection risk; chemokine receptor gene; alleleCCR5del32; meta-analysis
25.  Molecular Mechanisms of Induced Pluripotency 
Acta Naturae  2012;4(1):12-22.
In this review the distinct aspects of somatic cell reprogramming are discussed. The molecular mechanisms of generation of induced pluripotent stem (iPS) cells from somatic cells via the introduction of transcription factors into adult somatic cells are considered. Particular attention is focused on the generation of iPS cells without genome modifications via the introduction of the mRNA of transcription factors or the use of small molecules. Furthermore, the strategy of direct reprogramming of somatic cells omitting the generation of iPS cells is considered. The data concerning the differences between ES and iPS cells and the problem of epigenetic memory are also discussed. In conclusion, the possibility of using iPS cells in regenerative medicine is considered.
PMCID: PMC3372987  PMID: 22708059
reprogramming; iPS cells; ES cells; differentiation; transformation; pluripotency

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