Proteasomes in the brain of β2-microglobulin knockout mice

MHC class I molecules play an important role in synaptic plasticity of the mammalian nervous system. Proteolytic complexes (proteasomes) produce oligopeptides that are presented on cell surfaces in complexes with MHC class I molecules and regulate many cellular processes beside this. The goal of the present work was to study peculiarities in functioning of proteasomes and associated signaling pathways along with evaluation of NeuN and gFAP expression in different sections of the brain in mice with knockout of β2-microglobulin, a constituent of MHC class I molecules. It was found that the frontal cortex and the brainstem, structures with different ratio of NeuN and gFAP expression, are characterized by opposite changes in the proteasome pool under constant total proteasome levels in B2m-knockout mice in comparison with those in control animals. ChTL-activity as well as expression of LMP7 immune subunit and PA28 regulator of proteasomes was elevated in the cortex of B2m-knockout mice, while these indicators were decreased in the brainstem. The concentrations of the signaling molecules nNOS and HSP70 in B2m-knockout mice were increased in the cortex, while being decreased in the brainstem, and this indicates the possibility of control of expression of the LMP7 subunit and the regulator PA28 by these molecules. Changes in the proteasome pool observed in striatum of B2m-knockout mice are similar to those observed in the brainstem. At the same time, the cerebellum is characterized by a specific pattern of proteasome functioning in comparison with that in all other brain structures. In cerebellum the expression of immune subunits LMP7 and LMP2 and the regulator PA28 was increased, while expression of regulator PA700 was decreased. Deficiency of NeuN and gFAP was revealed in most brain compartments of B2m-knockout mice. Thus, increased expression of the above-mentioned immune subunits and the proteasome regulator PA28 in the cortex and cerebellum may compensate disturbances revealed in the brain structures and the absence of MHC class I molecules. Apparently, this promotes production of peptides necessary for cell-to-cell interactions and maintains nervous system plasticity in B2m-knockout mice.     

The study of some mechanisms of injurious effects of low-frequency noises

Low-frequency noise has been shown to cause certain functional changes in the organism of laboratory animals that manifest in changes of the state of the regulatory systems and metabolic disturbances at cellular and subcellular levels. The obtained data support the hypothesis of the mechanism of injurious effect of this physical factor including two basically correlated ways, i.e. the central mechanism associated with overexcitation of the hypotalamohypophysis-adrenal system and mediating the homeostatic parameters of the body, and the local one which is determined by a direct effect of low-frequency noise on highly organized structure of membraneous and genetic apparatus of cells.     

Activities of protein-inhibitors of proteases in seeds of different varieties of yellow and white lupine plants

Activities of protein-inhibitors of proteases and their correlation with the total content of protein and alkaloids in yellow and white lupine seeds were studied. Yellow lupine seeds showed lowe activities of protein-inhibitors. They also displayed negative correlation between activities of protein-inhibitors and the total content of protein and alkaloids.     

Exclusion of immune proteasomes from mouse ascitic carcinoma Krebs-II cells

Pools of 26S and 20S proteasomes were studied in the spleen, liver, lung, and ascitic carcinoma Krebs-II of mouse. Western blotting demonstrated that the pool of 26S proteasomes in ascitic carcinoma Krebs-II was twice that in control lung cells and did not significantly differ by total 26S proteasome quantities from the spleen and liver. At the same time, the level of immune subunit LMP7 was 12 times lower in it compared to lung proteasomes and 4–5 times lower compared to spleen and liver proteasomes. Immune subunit LMP2 was undetectable by this technique in the ascitic carcinoma in contrast to the lung, spleen, and liver. All immune subunits in the studied organs and ascitic carcinoma Krebs-II are components of 26S but not 20S proteasomes.     

Stimulatory Effect of Insulin and Epidermal Growth Factor on Activity of Protein Kinase A, Glucose-6-Phosphate Dehydrogenase, and Glycogen Synthase in Skeletal Muscles of Chick Embryos and Chickens

Insulin is able to produce two types of regulatory effects on muscles—metabolic and growth stimulating. Study of the effect of insulin and epidermal growth factor (EGF) on activity of cAMP-dependent protein kinase (PKA), glucose-6-phosphate dehydrogenase (G-6PDH), a starting enzyme of pentosephosphate pathway (PPP), and glycogen synthase (GS), a key enzyme of the glycogen synthesis, has shown that both types of the insulin effects do not arise simultaneously in the course of embryogenesis. The growth-stimulating effect mediated by adenylyl cyclase—cAMP is revealed since the 10th embryonal day. It was established for the first time that insulin could participate in growth stimulation by activating PKA in vivo and in vitro in muscles of the 10–14-day old embryos and the 8–10-day old chickens. The stimulating effect of insulin on G-6PDH activity is revealed since the same embryonal period and gradually increases. Insulin in vivo and in vitro simulates the glycogen synthase activity by increasing its conversion from non-active to active (GS-I) form only in the 15-day old embryos and in chickens. The stimulating effects of insulin and EGF on both G-6PDH activity (in embryos and chickens) and GS (in chickens) was shown to blocked by selective inhibitors of tyrosine kinases, thyrphostin 47 and genestein, in the dose-dependent manner, which indicates involvement of receptor of the tyrosine kinase type in these effects. The complex of the established facts permits concluding that insulin at early embryonal stages stimulates in the chicken muscles the PKA and G-6PDH activities involved in action of this hormone on growth, which is especially pronounced at the stage of myoblast proliferation. Meanwhile, the metabolic insulin effect (stimulation of the glycogen synthase system) appears in the second half of embryonal period and coincides in time with the period of muscle cell differentiation and active muscle contractures.     

Redox reactions in apoplast of growing cells

Redox reactions affecting the cell wall extensibility proceed in the apoplast of growing cells. The reactions involve dozens of oxidoreductases localized in cell walls (Class I and III heme peroxidases, FAD- and Cu-dependent amine oxidases, oxalate oxidase, ascorbate oxidase, superoxide dismutase, etc.) together with NADPH oxidase and quinone reductase of the plasma membrane. The cell wall extensibility decreases due to peroxidase-catalyzed phenolic cross-links of polymers. Cell growth is proven to be directly dependent on production of reactive oxygen species (ROS) in the apoplast. A special value is attached to hydroxyl radical OH?, which is able to locally cleave polysaccharides and, thus, increase wall extensibility. Generation of OH? results from one-electron reduction of H₂O₂ and, consequently, is related to the complex of enzymatic and spontaneous reactions of H₂O₂ turnover in the apoplast. The extensibility also depends on an ascorbate concentration in the apoplast and on a ratio of its oxidized to reduced forms. This dependence is expressed not only in the well-known down-regulation of phenols oxidation but also through pro-oxidant and signal activities. There is only indirect evidence of a role of apoplast-originated redox signaling in the cell growth regulation. In addition to ascorbate, the signaling may supposedly involve ROS, glutathione recycling reactions, numerous redox-sensitive peptides, and proteins localized in the cell wall and the plasma membrane.     

Characteristics of the spatio-temporal organization of the P300 component of AEP during the "active" and "passive" stimulus perception in healthy subjects

The concern of the work was in detection and analysis of P300 component of the acoustic evoked potential in healthy subjects in different experimental situations. During counting the rare sounds, P300 was most pronounced in the frontocentral and parietooccipital areas mainly of the left-hemisphere. The response shape was correlated with characteristics of the basic rhythm of the background EEG. Responses of simple and complex shapes were distinguished. The simplest responses were recorded in subjects with hypersynchronous alpha-rhythm. Analysis of three-dimensional dipole source localization showed that structures of the brainstem, limbic system, and frontal lobes participate in generation of the wave. In all the subjects, the decisive role in response generation was played by the brainstem structures. In persons with hypersynchronous alpha-rhythm, the contribution of the frontal lobes was less pronounced. During "passive" listening of sounds, P300 parameters significantly differed from those observed during counting only in 46% of cases (in persons having no hypersynchronous alpha-rhythm). A simplification of the response shape during "passive" listening was observed in these cases, the area of the maximal response expression was shifted to symmetrical areas of the right-hemisphere, the number of dipole sources reduced due to a decrease in the contribution of the frontal and limbic structures into the response generation.     

Specific Features of Repair DNA-Polymerases in Embryogenesis of the Loach

The current concept of eukaryotic DNA polymerases is considered, which are involved in nuclear DNA repair. The data are given on a new group of DNA polymerases that maintain the integrity of DNA structures without preliminary excision of damaged regions. A special attention is paid to specific features of the functioning of repair DNA polymerases in embryogenesis of the loach. A possible existence is discussed of the previously unknown pathway of DNA repair with participation of DNA polymerase as independent from the nuclear antigen of proliferating cells.