Vol 2, No 2 (2010)

The Russian Federation State Prize in Science and Technology for 2009 honoring scientists for "A Set of Scientific Works on the Development of Laser and Information Technologies in Medicine" (Presidential Decree no. 678, June 6, 2010) was awarded to V.Ya. Panchenko, doctor of physical and mathematical sciences, academician of the Russian Academy of Sciences, director of the Institute of Laser and Information Technologies, Russian Academy of Sciences; to A.A. Potapov, doctor of medical sciences, Russian Academy of Medical Sciences, deputy director of the Burdenko Neurosurgery Research Institute, Medical Academy of Medical Sciences; and to V.I. Chissov, doctor of medical sciences, academician of the Russian Academy of Medical Sciences, director of Herzen's Cancer Research Institute, Moscow.

Induced pluripotent stem cells (iPSCs) are a new type of pluripotent cells that can be obtained by reprogramming animal and human differentiated cells. In this review, issues related to the nature of iPSCs are discussed and different methods of iPSC production are described. We particularly focused on methods of iPSC production without the genetic modification of the cell genome and with means for increasing the iPSC production efficiency. The possibility and issues related to the safety of iPSC use in cell replacement therapy of human diseases and a study of new medicines are considered.

This review focuses on new trends in nucleoside biotechnology, which have emerged during the last decade. Continuously growing interest in the study of this class of compounds is fueled by a number of factors: (i) a growing need for large-scale production of natural 2'-deoxy-β-D-ribonucleosides as well as their analogs with modifications in the carbohydrate and base fragments, which can then be used for the synthesis and study of oligonucleotides, including short-interfering RNA (siRNA), microRNA (miRNA), etc.; (ii) a necessity for the development of efficient practical technologies for the production of biologically important analogs of natural nucleosides, including a number of anticancer and antiviral drugs; (iii) a need for further study of known and novel enzymatic transformations and their use as tools for the efficient synthesis of new nucloside analogs and derivates with biomedical potential. This article will review all of these aspects and also include a brief retrospect of this field of research.

ABSTRACT A bioinformatic and phylogenetic study has been performed on a family of penicillin-binding proteins including D-aminopeptidases, D-amino acid amidases, DD-carboxypeptidases, and β-lactamases. Significant homology between D-aminopeptidase from Ochrobactrum anthropi and other members of the family has been shown and a number of conserved residues identified as S62, K65, Y153, N155, H287, and G289. Three of those (Ser62, Lys65, and Tyr153) form a catalytic triangle - the proton relay system that activates the generalized nucleophile in the course of catalysis. Molecular modeling has indicated the conserved residue Lys65 to have an unusually low pKa value, which has been confirmed experimentally by a study of the pH-profile of D-aminopeptidase catalytic activity. The resulting data have been used to elucidate the role of Lys65 in the catalytic mechanism of D-aminopeptidase as a general base for proton transfer from catalytic Ser62 to Tyr153, and vice versa, during the formation and hydrolysis of the acylenzyme intermediate.

We compared the thermal aggregation properties of two isoforms of the isolated myosin head (myosin subfragment 1, S1) containing different “essential” (or “alkali”) light chains, A1 or A2. Temperature dependencies for the aggregation of these two S1 isoforms, as measured by the increase in turbidity, were compared with the temperature dependencies of their thermal denaturation obtained from differential scanning calorimetry (DSC) experiments. At relatively high ionic strength (in the presence of 100 mM KCl) close to its physiological values in muscle fibers, we have found no appreciable difference between the two S1 isoforms in their thermally induced aggregation. Under these conditions, the aggregation of both S1 isoforms was independent of the protein concentration and resulted from their irreversible denaturation, which led to the cohesion of denatured S1 molecules. In contrast, a significant difference between these S1 isoforms was revealed in their aggregation measured at low ionic strength. Under these conditions, the aggregation of S1 containing a light chain A1 (but not A2) was strongly dependent on protein concentration, the increase of which (from 0.125 to 2.0 mg/ml) shifted the aggregation curve by ~10 degrees towards the lower temperatures. It has been concluded that the aggregation properties of this S1 isoform at low ionic strength is basically determined by intermolecular interactions of the N-terminal extension of the A1 light chain (which is absent in the A2 light chain) with other S1 molecules. These interactions seem to be independent of the S1 thermal denaturation, and they may take place even at low temperature.

The cytotoxic properties of cytotoxins (CTs) from snake venom are mediated by their interaction with the cell membrane. The hydrophobic pattern containing the tips of loops I-III and flanked by polar residues is known to be a membrane-binding motif of CTs. However, this is not enough to explain the difference in activity among various CTs which are similar in sequence and in 3D structure. The mechanism of further CT-membrane interaction leading to pore formation and cell death still remains unknown. Published experimental data on the specific interaction between CT and low molecular weight anionic components (sulphatide) of the bilayer point to the existence of corresponding ligand binding sites on the surface of toxin molecules. In this work we study the membrane-lytic properties of CT I, CT II (Naja oxiana), and CT 4 (Naja kaouthia), which belong to different structural and functional types (P- and S-type) of CTs, by measuring the intensity of a fluorescent dye, calcein released from liposomes containing a phosphatidylserine (PS) lipid as an anionic component. Using molecular docking simulations, we find and characterize three sites in CT molecules that can potentially bind the PS polar head. Based on the data obtained, we suggest a hypothesis that CTs can specifically interact with one or more of the anionic lipids (in particular, with PS) contained in the membrane, thus facilitating the interaction between CTs and the lipid bilayer of a cell membrane.

The isolation and study of autologous human stem cells remain among the most urgent problems in cell biology and biomedicine to date. Induced pluripotent stem cells can be derived from human somatic cells by the overexpression of a number of genes. In this study we reprogrammed fetal human skin fibroblasts by transduction with retroviral vectors carrying murine Oct4, Sox2, Klf4, and c-Myc cDNAs. As a result, cells with the protein expression and gene transcription pattern characteristic of human embryonic stem cells were derived. These induced pluripotent cells are capable of differentiation in vitro into the ectoderm, mesoderm, and endoderm derivatives.