Vol 7, No 1 (2015)


Theories of Aging: An Ever-Evolving Field

Sergiev P.V., Dontsova O.A., Berezkin G.V.


Senescence has been the focus of research for many centuries. Despite significant progress in extending average human life expectancy, the process of aging remains largely elusive and, unfortunately, inevitable. In this review, we attempted to summarize the current theories of aging and the approaches to understanding it.

Acta Naturae. 2015;7(1):9-18
pages 9-18 views

Model Systems of Motor Neuron Diseases As a Platform for Studying Pathogenic Mechanisms and Searching for Therapeutic Agents

Valetdinova K.R., Medvedev S.P., Zakian S.M.


Over the past 30 years, many molecular genetic mechanisms underlying motor neuron diseases (MNDs) have been discovered and studied. Among these diseases, amyotrophic lateral sclerosis (ALS), which causes the progressive degeneration and death of central and peripheral motor neurons, and spinal muscular atrophy (SMA), which is one of the inherited diseases that prevail among hereditary diseases in the pattern of child mortality, hold a special place. These diseases, like most nerve, neurodegenerative, and psychiatric diseases, cannot be treated appropriately at present. Artificial model systems, especially those that are based on the use of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are of paramount importance in searching for adequate therapeutic agents, as well as for a deep understanding of the MND pathogenesis. This review is mainly focused on the recent advance in the development of and research into cell and animal models of ALS and SMA. The main issues concerning the use of cellular technologies in biomedical applications are also described.

Acta Naturae. 2015;7(1):19-36
pages 19-36 views

Structure and Biological Functions of β-Hairpin Antimicrobial Peptides

Panteleev P.V., Bolosov I.A., Balandin S.V., Ovchinnikova T.V.


Antimicrobial peptides (AMPs) are evolutionarily ancient factors of the innate immune system that serve as a crucial first line of defense for humans, animals, and plants against infection. This review focuses on the structural organization, biosynthesis, and biological functions of AMPs that possess a β-hairpin spatial structure. Representatives of this class of AMPs are among the most active antibiotic molecules of animal origin. Due to their wide spectrum of activity and resistance to internal environmental factors, natural β-hairpin AMPbased compounds might become the most promising drug candidates.

Acta Naturae. 2015;7(1):37-47
pages 37-47 views

Regulation of PGC-1α Isoform Expression in Skeletal Muscles

Popov D.V., Lysenko E.A., Kuzmin I.V., Vinogradova O.L., Grigoriev A.I.


The coactivator PGC-1α is the key regulator of mitochondrial biogenesis in skeletal muscle. Skeletal muscle expresses several PGC-1α isoforms. This review covers the functional role of PGC-1α isoforms and the regulation of their exercise-associated expression in skeletal muscle. The patterns of PGC-1α mRNA expression may markedly differ at rest and after muscle activity. Different signaling pathways are activated by different physiological stimuli, which regulate the expression of the PGC-1α gene from the canonical and alternative promoters: expression from a canonical (proximal) promoter is regulated by activation of the AMPK; expression from an alternative promoter, via a β2-adrenergic receptor. All transcripts from both promoters are subject to alternative splicing. As a result, truncated isoforms that possess different properties are translated: truncated isoforms are more stable and predominantly activate angiogenesis, whereas full-length isoforms manly regulate mitochondrial biogenesis. The existence of several isoforms partially explains the broad-spectrum function of this protein and allows the organism to adapt to different physiological stimuli. Regulation of the PGC-1α gene expression by different signaling pathways provides ample opportunity for pharmacological influence on the expression of this gene. Those opportunities might be important for the treatment and prevention of various diseases, such as metabolic syndrome and diabetes mellitus. Elucidation of the regulatory mechanisms of the PGC-1α gene expression and their functional role may provide an opportunity to control the expression of different isoforms through exercise and/or pharmacological intervention.

Acta Naturae. 2015;7(1):48-59
pages 48-59 views

Research Articles

The Role of Ala198 in the Stability and Coenzyme Specificity of Bacterial Formate Dehydrogenases

Alekseeva A.A., Fedorchuk V.V., Zarubina S.A., Sadykhov E.G., Matorin A.D., Savin S.S., Tishkov V.I.


It has been shown by an X-ray structural analysis that the amino acid residues Ala198, which are located in the coenzyme-binding domain of NAD+-dependent formate dehydrogenases (EC, FDH) from bacteria Pseudomonas sp.101 and Moraxella sp. C-1 (PseFDH and MorFDH, respectively), have non-optimal values of the angles ψ and φ. These residues were replaced with Gly by site-directed mutagenesis. The mutants PseFDH A198G and MorFDH A198G were expressed in E.coli cells and obtained in active and soluble forms with more than 95% purity. The study of thermal inactivation kinetics showed that the mutation A198G results in a 2.5- fold increase in stability compared to one for the wild-type enzymes. Kinetic experiments indicate that A198G replacement reduces the K M NAD+ value from 60 to 35 and from 80 to 45 μM for PseFDH and MorFDH, respectively, while the K M HCOO- value remains practically unchanged. Amino acid replacement A198G was also added to the mutant PseFDH D221S with the coenzyme specificity changed from NAD + to NADP +. In this case, an increase in thermal stability was also observed, but the influence of the mutation on the kinetic parameters was opposite: KM increased from 190 to 280 μM and from 43 to 89 mM for NADP + and formate, respectively. According to the data obtained, inference could be drawn that earlier formate dehydrogenase from bacterium Pseudomonas sp. 101 was specific to NADP +, but not to NAD +.

Acta Naturae. 2015;7(1):60-69
pages 60-69 views

Reconstruction of Rabbit Urethral Epithelium with Skin Keratinocytes

Rogovaya O.S., Fayzulin A.K., Vasiliev A.V., Kononov A.V., Terskikh V.V.


We have investigated the living skin equivalent (LSE) as an alternative source of plastic material for closing full-thickness epithelial-stromal urethral injuries. The possibility of transdifferentiation of epidermal keratinocytes, a component of 3D tissue constructs, was investigated in vivo in a model of the recovery of urethral injuries in laboratory rabbits. Autologous grafting of LSE in de-epithelialized urethra showed that skin keratinocytes placed in a specific in vivo microenvironment can be incorporated into the damaged area and function as urothelium. The use of EGFP transfected keratinocytes allowed us to identify transplanted cells. The reconstructed urethral tubes did not develop strictures or fistulas at the site of the grafted LSE. Immunohistochemical studies of neo-urothelium revealed EGFP-positive cells expressing the urothelial markers K7 and UP3.

Acta Naturae. 2015;7(1):70-77
pages 70-77 views

Influence of Drug Resistance Mutations on the Activity of HIV-1 Subtypes A and B Integrases: a Comparative Study

Shadrina O.A., Zatsepin T.S., Agapkina Y.Y., Isaguliants M.G., Gottikh M.B.


Integration of human immunodeficiency virus (HIV-1) DNA into the genome of an infected cell is one of the key steps in the viral replication cycle. The viral enzyme integrase (IN), which catalyzes the integration, is an attractive target for the development of new antiviral drugs. However, the HIV-1 therapy often results in the IN gene mutations inducing viral resistance to integration inhibitors. To assess the impact of drug resistance mutations on the activity of IN of HIV-1 subtype A strain FSU-A, which is dominant in Russia, variants of the consensus IN of this subtype containing the primary resistance mutations G118R and Q148K and secondary compensatory substitutions E138K and G140S were prepared and characterized. Comparative study of these enzymes with the corresponding mutants of IN of HIV-1 subtype B strains HXB-2 was performed. The mutation Q148K almost equally reduced the activity of integrases of both subtypes. Its negative effect was partially compensated by the secondary mutations E138K and G140S. Primary substitution G118R had different influence on the activity of proteins of the subtypes A and B, and the compensatory effect of the secondary substitution E138K also depended on the viral subtype. Comparison of the mutants resistance to the known strand transfer inhibitors raltegravir and elvitegravir, and a new inhibitor XZ-259 (a dihydro-1H-isoindol derivative), showed that integrases of both subtypes with the Q148K mutation were insensitive to raltegravir and elvitegravir but were effectively inhibited by XZ-259. The substitution G118R slightly reduced the efficiency of IN inhibition by raltegravir and elvitegravir and caused no resistance to XZ_259.

Acta Naturae. 2015;7(1):78-86
pages 78-86 views

The Role of HCV E2 Protein Glycosylation in Functioning of Virus Envelope Proteins in Insect and Mammalian Cells

Orlova O.V., Drutsa V.L., Spirin P.V., Ivanov A.V., Prasolov V.S., Rubtsov P.M., Kochetkov S.N., Beljelarskaya S.N.


The hepatitis C virus (HCV) envelope proteins E1 and E2, being virion components, are involved in the formation of infectious particles in infected cells. The detailed structure of the infectious particle of HCV remains poorly understood. Moreover, the virion assembly and release of virions by the cell are the least understood processes. It is believed that virion properties depend on glycosylation of the virus envelope proteins in a cell, while glycansat several glycosylation sites of these proteins play a pivotal role in protein functioning and the HCV life cycle. N-glycans of glycoproteins can influence viral particle formation, virus binding to cell surface, and HCV pathogenesis. We studied the effect of glycans on the folding ofthe E2 glycoprotein, formation of functional glycoprotein complexes and virus particles in insect and mammalian cells. In order to investigate these processes, point mutations of the N-glycosylation sites of HCV protein E2 (genotype 1b strain 274933RU) were generated and the mutant proteins were further analyzed in the baculovirus expression system. Elimination of the single glycosylation sites of the E2 glycoprotein, except for the N6 site, did not affect its synthesis efficiency in Sf9 insect cells, while the electrophoretic mobility of mutant proteins increased in proportion to the decrease in the number of glycosylation sites. The level of synthesis of HCV glycoprotein E2 in human HEK293T cells depended on the presence of glycans at the N1 and N8 glycosylation sites in contrast to Sf9 cells. At the same time, elimination of glycans at the N1, N2, and N10 sites led to the accumulation of unproductive E1E2 dimers as aggregates and productive assembly suppression of virus-like particles both in insect and mammalian cells. In addition, elimination of single glycosylation sites of HCV E2 had no impact on the RNA synthesis of structural proteins and formation of virus-like particles in insect and mammalian cells.

Acta Naturae. 2015;7(1):87-97
pages 87-97 views

New Nanobiocomposite Materials for Bioelectronic Devices

Pankratov D.V., González-Arribas E., Parunova Y.M., Gorbacheva M.A., Zeyfman Y.S., Kuznetsov S.V., Lipkin A.V., Shleev S.V.


We have developed and synthesized nanobiocomposite materials based on graphene, poly(3,4-ethylenedioxythiophene), and glucose oxidase immobilized on the surface of various nanomaterials (gold nanoparticles and multi-walled carbon nanotubes) of different sizes (carbon nanotubes of different diameters). Comparative studies of the possible influence of the nanomaterial’s nature on the bioelectrocatalytic characteristics of glucose-oxidizing bioanodes in a neutral phosphate buffer solution demonstrated that the bioelectrocatalytic current densities of nanocomposite-based bioanodes are only weakly dependent on the size of the nanomaterial and are primarily defined by its nature. The developed nanobiocomposites are promising materials for new bioelectronic devices due to the ease in adjusting their capacitive and bioelectrocatalytic characteristics, which allows one to use them for the production of dual-function electrodes: i.e., electrodes which are capable of generating and storing electric power simultaneously.

Acta Naturae. 2015;7(1):98-101
pages 98-101 views

Selective Protective Potency of Yersinia pestis ΔnlpD Mutants

Dentovskaya S.V., Ivanov S.A., Kopylov P.K., Shaikhutdinova R.Z., Platonov М.E., Kombarova T.I., Gapel’chenkova T.V., Balakhonov S.V., Anisimov A.P.


It has recently been shown that the NlpD lipoprotein is essential to Yersinia pestis virulence and that subcutaneous administration of the nlpD mutant could protect mice against bubonic and pneumonic plague better than the EV vaccine strain [PLoS One 2009. V. 4. № 9. e7023]. In this study, similar ΔnlpD mutants were generated on the basis of other Y. pestis parent strains, including strains from the subspecies microtus, which is avirulent to guinea pigs and humans. Comparative testing confirmed that immunization of mice with ΔnlpD mutants induces immunity 105 times more potent than the one induced by the administration of the EV vaccine strain. At the same time, NlpD- bacteria failed to protect guinea pigs in the case of a subcutaneous challenge with Y. pestis, inducing a 106 times less potent protection compared with that conferred by immunization with the EV vaccine strain. The possible causes of the observed phenomena are discussed.

Acta Naturae. 2015;7(1):102-108
pages 102-108 views

Interaction with Serum Albumin As a Factor of the Photodynamic Efficacy of Novel Bacteriopurpurinimide Derivatives

Аkimova А.V., Rychkov G.N., Grin М.А., Filippova N.A., Golovina G.V., Durandin N.A., Vinogradov A.M., Коkrashvili Т.А., Mironov А.F., Shtil А.А., Кuzmin V.А.


Optimization of the chemical structure of antitumor photosensitizers (PSs) is aimed at increasing their affinity to a transport protein, albumin and irreversible light-induced tumor cell damage. Bacteriopurpurinimide derivatives are promising PSs thanks to their ability to absorb light in the near infrared spectral region. Using spectrophotometry, we show that two new bacteriopurpurinimide derivatives with different substituents at the N atoms of the imide exocycle and the pyrrole ring A are capable of forming non-covalent complexes with human serum albumin (HSA). The association constant (calculated with the Benesi-Hildebrand equation) for N-ethoxybacteriopurpurinimide ethyloxime (compound 1) is higher than that for the methyl ether of methoxybacteriopurpurinimide (compound 2) (1.18×10 5 M-1 vs. 1.26×10 4 M -1, respectively). Molecular modeling provides details of the atomic interactions between 1 and 2 and amino acid residues in the FA1 binding site of HSA. The ethoxy group stabilizes the position of 1 within this site due to hydrophobic interaction with the protein. The higher affinity of 1 for HSA makes this compound more potent than 2 in photodynamic therapy for cultured human colon carcinoma cells. Photoactivation of 1 and 2 in cells induces rapid (within a few minutes of irradiation) necrosis. This mechanism of cell death may be efficient for eliminating tumors resistant to other therapies.

Acta Naturae. 2015;7(1):109-116
pages 109-116 views

Short communications

Recombinant α-NAcetylgalactosaminidase from Marine Bacterium-Modifying A Erythrocyte Antigens

Balabanova L.A., Golotin V.А., Bakunina I.Y., Slepchenko L.V., Isakov V.V., Podvolotskaya A.B., Rasskazov V.А.


A plasmid based on pET-40b was constructed to synthesize recombinant α-N-acetylgalactosaminidase of the marine bacterium Arenibacter latericius KMM 426 T (α-AlNaGal) in Escherichia coli cells. The yield of α-Al-NaGal attains 10 mg/ml with activity of 49.7 ± 1.3 U at 16°C, concentration of inductor 2 mM, and cultivation for 12 h. Techniques such as anion exchange, metal affinity and gel filtration chromatography to purify α-AlNaGal were applied. α-AlNaGal is a homodimer with a molecular weight of 164 kDa. This enzyme is stable at up to 50°C with a temperature range optimum activity of 20-37°C. Furthermore, its activity is independent of the presence of metal ions in the incubation medium. 1H NMR spectroscopy revealed that α-AlNaGal catalyzes the hydrolysis of the O-glycosidic bond with retention of anomeric stereochemistry and possesses a mechanism of action identical to that of other glycoside hydrolases of the 109 family. α-AlNaGal reduces the serological activity of A erythrocytes at pH 7.3. This property of α-AlNaGal can potentially be used for enzymatic conversion of A and AB erythrocytes to blood group O erythrocytes.

Acta Naturae. 2015;7(1):117-120
pages 117-120 views

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