KH-Domain Poly(C)-Binding Proteins as Versatile Regulators of Multiple Biological Processes.

Five known members of the family of KH-domain poly(C)-binding proteins (Pcbp1-4, hnRNP-K) have an unusually broad spectrum of cellular functions that include regulation of gene transcription, regulation of pre-mRNA processing, splicing, mRNA stability, translational silencing and enhancement, the control of iron turnover, and many others. Mechanistically, these proteins act via nucleic acid binding and protein-protein interactions. Through performing these multiple tasks, the KH-domain poly(C)-binding family members are involved in a wide variety of biological processes such as embryonic development, cell differentiation, and cancer. Deregulation of KH-domain protein expression is frequently associated with severe developmental defects and neoplasia. This review summarizes progress in studies of the KH-domain proteins made over past two decades. The review also reports our recent finding implying an involvement of the KH-factor Pcbp1 into control of transition from naïve to primed pluripotency cell state.

[Investigation of transcriptional regulation of Oct4 (POU5F1) gene with distal enhancer].

Investigations of transcriptional regulation of Oct4 gene in mouse embryonic stem cells have revealed an important cis-element--the distal enhancer (DE). DE consists of two functionally significant elements--DEa and DEb. Both elements are necessary to complete the DE-mediated expression of Oct4 gene in pluripotent cells. The most likely candidates for the binding site DEb are Oct4 itself in complex with Sox2 protein. It remains unclear which transcriptional proteins bind to the DEa site and what is the mechanism of the co-operation between the DEa and the DEb. Through the use of using the EMSA and chromatographic fractionation of proteins from extracts of mouse embryonic stem cells and mouse tissues, were isolated proteins specifically interacting with the sequence DEa Oct4 gene.

The angiotensin converting enzyme I/D polymorphism in Russian athletes.

The deletion (D) allele of the human ACE gene is associated with higher ACE activity than the insertion (I) allele. There is controversy as to whether the ACE genotype may be associated with elite athletic status; recent studies have identified no significant associations amongst those drawn from mixed sporting disciplines. However, such lack of association may reflect the mixed nature of such cohorts, given that an excess frequency of the I allele has been reported amongst elite endurance athletes, and an excess of the D allele amongst those engaged in more power-orientated sports. We examined this hypothesis by determining ACE I/D allele frequency amongst 217 Russian athletes (swimmers, skiers, triathletes and track-and-field participants) prospectively stratified by performance ('outstanding' or 'average'), and the duration of their event (SDA (<1 min), MDA (1 to 20 min), and LDA (>20 min): short, middle and long distance athletes respectively). ACE genotype and allele frequencies were compared to 449 controls. ACE genotype frequency amongst the whole cohort, or the outstanding athletes alone, was no different to that amongst sedentary controls. However, there was an excess of the D allele (frequency 0.72, P=0.001) amongst the outstanding SDA group, and an excess of the I allele (frequency 0.63, P=0.032) amongst the outstanding MDA group. These findings were replicated in the outstanding swimmers, with track and field SDA similarly demonstrating an excess of the D allele (P=0.01). There was no association found between the outstanding LDA and ACE genotype (P=0.27). These data not only confirm an excess of the D allele in elite SDA, and I allele in elite MDA, but also offer an explanation as to why any such association may be hard to detect amongst a heterogeneous cohort of mixed athletic ability and discipline.

Dephosphorylation of histone gamma-H2AX during repair of DNA double-strand breaks in mammalian cells and its inhibition by calyculin A.

The induction of DNA double-strand breaks (DSBs) by ionizing radiation in mammalian chromosomes leads to the phosphorylation of Ser-139 in the replacement histone H2AX, but the molecular mechanism(s) of the elimination of phosphorylated H2AX (called gamma-H2AX) from chromatin in the course of DSB repair remains unknown. We showed earlier that gamma-H2AX cannot be replaced by exchange with free H2AX, suggesting the direct dephosphorylation of H2AX in chromatin by a protein phosphatase. Here we studied the dynamics of dephosphorylation of gamma-H2AX in vivo and found that more than 50% was dephosphorylated in 3 h, but a significant amount of gamma-H2AX could be detected even 6 h after the induction of DSBs. At this time, a significant fraction of the gamma-H2AX nuclear foci co-localized with the foci of RAD50 protein that did not co-localize with replication sites. However, gamma-H2AX could be detected in some cells treated with methyl methanesulfonate which accumulated RAD18 protein at stalled replication sites. We also found that calyculin A inhibited early elimination of gamma-H2AX and DSB rejoining in vivo and that protein phosphatase 1 was able to remove phosphate groups from gamma-H2AX-containing chromatin in vitro. Our results confirm the tight association between DSBs and gamma-H2AX and the coupling of its in situ dephosphorylation to DSB repair.

[Secretion of lysozyme by blood neutrophils during physical exertion]. / Sekretsiia lizotsima neitrofilami krovi pri fizicheskoi nagruzke.

The effect of physical exercise on the lysozyme release from the blood neutrophils was investigated. The lysozyme RIA was adopted to evaluate its concentration. The RIA main parameters developed on the basis of specific antiserum and 125I-lysozyme, were noted. Physical exercise increased the lysozyme concentration in plasma and decreased it in neutrophils. During 2-hr resting, the partial normalizing of the values occurred. The data obtained suggest the above effect of physical exercise on the neutrophil secretory function to be a mechanism of suppression of the functional neutrophil activity.

[The effect of physical exertion on the activity of calpains and myeloperoxidase level in skeletal muscles of rats]. / Vliianie fizicheskikh nagruzok na aktivnost' kalpainov i soderzhanie mieloperoksidazy v skeletnykh myshtsakh krys.

It has been established that the activity of calpains and the amount of neutrophil myeloperoxidase in skeletal muscles of rats increases after the 24-48 h-rest, that followed an intensive single physical exercise. Adaptation which appears as a result of systematic physical exercises causes less pronounced changes in the activity of proteolytic enzymes. Free ubiquitin content in skeletal muscles remains unchanged during training and in posttraining periods.

[Radioimmunological assay of human lysozyme and effect of exertion on its blood level]. / Radioimmunologicheskii metod analiza lizotsima cheloveka i vliianie fizicheskoi nagruzki na ego soderzhanie v krovi.

Radioimmunoassay (RIA) of human lysozyme was developed using 125I-lysozyme and specific antiserum to the enzyme. Titre of antibodies produced in the antiserum was as high as 1:81,000, affinity constant constituted 1.3.10(9) M/L. Optimum patterns of the RIA were achieved under the following conditions: B0 = 50-55%, T = 25-30.10(3) cpm, BSA = 0.5%, NaCl = 0.85%, charcoal 2.5%. The antibody-antigen reaction was carried out within 30 min, 30 and 15 min at 37 degrees, 20 degrees and 4 degrees, respectively. The RIA enabled to estimate lysozyme with sensitivity of 0.25 ng/ml, while the standard curve was optimal within the range of 0.1-1.0 ng/tube. Intra- and inter-assay coefficients did not exceed 4% and 8%, respectively. Recovery of the standard lysozyme concentration was equal to 96.5 +/- +/- 0.8%. As shown by the RIA intensive physical exercises resulted in an increase of lysozyme content in blood, which appears to occur due to the enzyme secretion from phagocytes. Calculation of the secretion index may be used for evaluation of blood phagocytes functional state.