Exploring bioactivity potential of polyphenolic water-soluble lignin derivative.

Many natural substances exhibit anti-inflammatory activity and considerable potential in prophylaxis and treatment of allergies. Knowing exact molecular targets, which is required for developing these as medicinal products, is often challenging for multicomponent compositions. In the present study we examined novel polyphenolic substance, a water-soluble fraction of wood lignin (laboratory code BP-Cx-1). In our previous study, a number of polyphenolic components of BP-Cx-1 (flavonoids, sapogenins, phenanthrenes etc.) were identified as the major carriers of biological activity of BP-Cx drug family, and several molecular targets involved in cancer and/or inflammation signaling pathways were proposed based on the results of the in vitro and in silico screening studies. In the present study, half maximal inhibitory concentration (IC50) of BP-Cx-1 was established with a radioligand method and a range of IC50 values between 22.8 and 40.3 µg/ml were obtained for adenosine receptors A1, A2A and prostaglandin receptors EP2, IP (PGI2). IC50 for serotonin 5-HT1 and for glucocorticoid GR receptors were 3.0 µg/ml and 12.6 µg/ml, respectively, both being within the range of BP-Cx-1 concentrations achievable in in vivo models. Further, distribution of [3H] labelled BP-Cx-1 in NIH3T3 murine fibroblasts and MCF7/R carcinoma cells was studied with autoradiography. [3H]-BP-Cx-1 (visualized as silver grains produced by tritium beta particles) was mainly localized along the cell membrane, in the perinuclear region and in the nucleus, suggesting ability of BP-Cx-1 to enter cells and bind to membrane or cytosol receptors. In our experiment, we observed the effect of BP-Cx-1 on maturation of dendritic cells (DCs): downregulation of expression of the lipid-presentation molecule CD1a, co-stimulatory molecules CD80, CD83 and CD 40, decreased production of pro-inflammatory cytokines IL-4 and TNF-α and increased production of anti-inflammatory cytokine IL-10. It is hypothesized that [3H]-BP-Cx-1 detectable in the nucleus is part of the activated GR complex, known to be involved in regulation of transcription of genes responsible for the anti-inflammatory response. Based on IC50, cell distribution data and results of the experiment with DCs it is suggested that the in vivo effects of BP-Cx-1 are mediated via GR and 5-HT1 receptors thus promoting development of tolerogenic effector function in dendritic cells.

[PEGylated recombinant L-asparaginase from Erwinia carotovora: Production, properties, and potential applications].

N-hydroxysuccinimide ester of monomethoxy polyethylene glycol hemisuccinate was synthesized. It acylated amino groups in a molecule of recombinant L-asparaginase from Erwinia carotovora. A method of L-asparaginase modification by the obtained activated polyethylene glycol derivative was developed. The best results were produced by modification of the enzyme with a 25-fold excess of reagent relative to the enzyme tetramer. The modified L-asparaginase was isolated from the reaction mixture by gel filtration on Sepharose CL-6B. The purified bioconjugate did not contain PEG unbound to the protein, demonstrated high catalytic activity, and exhibited antiproliferative action on cell cultures.

Protein kinase A: regulation and receptor-mediated delivery of antisense oligonucleotides and cytotoxic drugs.

Protein kinases help regulate eukaryotic cell division. We investigated the regulation of cAMP-dependent protein kinase A (PKA) and casein kinase (CK) type I activity in normal cells and in cancer. To assess this activity in biopsies we suggest a new parameter--the ratio of CK activity and total PKA activity divided by cAMP concentration: CK/PKA/cAMP. In 98 samples of colon mucosa in normal, inflamed, polyp, and adenocarcinoma cells, we found this parameter to be fairly constant in normal conditions and increased 10-fold in colon cancer; the ratio does not depend on the place of biopsy or the patient's age or sex. Experiments with model systems of concanavalin A-stimulated lymphocytes and regenerating rat liver showed that in normal cell proliferation the parameter increases 2-3-fold, as compared to a 30-fold increase in cancer. Unlike normal cells, malignant cells show CK activation and decrease of cAMP; therefore, PKA activity decreases. This suggests a correlation of CK and PKA activity and significant damage to their regulation at pathological changes of tissue proliferation. To further study concerted CK and PKA regulation we used monoclonal antibodies (mAbs) against cAMP-dependent protein kinase regulatory subunit RKII beta. We produced 11 antibodies in three groups: inhibiting, which block cAMP binding with RII beta and inhibit holoenzyme formation (RS6); activating, which enhance cAMP binding and do not affect holoenzyme formation (RS28); and neutral (RS17). To investigate mAb influence on protein kinase regulation in live cells we permeabilized pheochromocytoma PC12 by digitonin. When used at 5-microM concentration for 5 min, digitonin allowed us to deliver mAb into PC12 cells at 30-34-nM concentration, leaving 68-75% viable cells. Protein kinase activity was measured within 0.5 and 4 h after incorporation of mAbs into cells. After 30 min incorporation, mAb RS6 blocked PKA activation in PC12 cells under the influence of cAMP; other mAbs showed no effect. mAb RS6 caused a 4-fold increase of free C subunit activity 4 h after incorporation. mAb RS38 decreased R2C2 activity and did not influence C subunit activity. The change of free C subunit activity caused by mAb incorporation was followed by a synchronized, well-balanced change of CK type I activity, which suggests a correlation between the two phosphorylation systems of cell proteins.

Incorporation of monoclonal antibodies in living rat pheochromocytoma PC12 cells. Evidence for the intracellular formation of immune complex between the incorporated antibody and a target protein.

PC12 cells permeabilized with a low concentration of digitonin (5 microM) under controlled conditions were loaded with monoclonal antibodies (MoAb) against the regulatory subunit type II (RII) of cAMP-dependent protein kinase. After digitonin removal from the nutrient medium (DMEM) the loaded cells repaired within 20-30 min and recontinued growth. The inserted MoAb stayed in the repaired cells at least for several hours. MoAb inhibiting the cAMP binding activity of neural RII [Grozdova et al. (1992) Biochem. Int. 27, 811-822; Sveshnikova et al. (1996) Biochem. Int. 39, 1063-1070] were shown to bind the target antigen inside the cells and influence the properties of intracellular protein kinases.

Properties of the regulatory subunit of cAMP-dependent protein kinase type II from human brain.

The regulatory subunit type II (RII) of cAMP-dependent protein kinase purified from human brain was represented by two proteins with apparent molecular masses of 51-52 kD and 54 kD. Dephosphorylation of human RII containing 3 mol phosphate/mol protein did not change the electrophoretic pattern. One-dimensional peptide mapping of 51-52 kD and 54 kD proteins after digestion with St. aureus V8 protease evidenced to their being distinct proteins. The data obtained permit to assume that human RII of neural type is represented by two isoforms.

Immunochemical studies on human, bovine and pig brain regulatory subunits of cAMP-dependent protein kinase type II.

Regulatory subunits type II (RII) purified from human, pig and bovine brains were compared using II monoclonal antibodies (MoAb) against bovine brain RII. Bovine RII has at least 5 antigenic sites located in the N-terminal 1-110 residues. Immunochemical difference detected between human and animal RII was more pronounced than between pig and bovine RII. Certain MoAb influenced R-cAMP binding and holoenzyme formation. RII of the three species responded to MoAb attachment in a similar fashion. The results suggest that anchoring of neural protein kinase via the N-terminal part of RII may influence the enzyme activity.

Antibodies to the regulatory subunit of cAMP-dependent protein kinase type II from bovine brain inhibit the holoenzyme formation.

Mouse monoclonal antibodies to the bovine brain regulatory subunit type II (RII) were produced and antibodies of 11 clones were characterized. We determined their subclass, affinity constants, competivity and influence on two RII functions, namely cAMP binding and inhibition of the catalytic subunit (C) activity. 4 clones produced antibodies that increased RII-cAMP binding 1,5-2-fold. Antibodies of other 3 clones prevented R-C association and inhibition of C phosphotransferase activity. Some antibodies affected neither of these RII functions.

[Cyclic AMP content, protein kinase activity, and DNA structure in resting and proliferating peripheral blood lymphocytes and in human T-lymphoma cells]. / Soderzhanie cAMP, aktivnost' proteinkinaz i struktura DNK v pokoiashchikhsia i proliferiruiushchikh limfotsitakh perifericheskoi krovi i v kletkakh T-limfomy cheloveka.

Alterations of DNA structure, of cAMP content, of cAMP-dependent histokinases (HK) activity and cAMP-independent casein kinases (CK) activity were studied during transformation of resting cells to proliferation. These patterns were studied in human lymphocytes from peripheral blood immediately after their isolation and after cultivation within 3 days in presence of concanavalin A (ConA) or without the mitogen as well as in cultivated cells of human T-lymphoma Jurkat. Increase in content of alkaline labile sites in DNA, in activity of CK as well as distinct increase in content of cAMP were detected within the first 18 hrs of lymphocytes cultivation both in presence of ConA or without it. Early steps of cell transformation from G0 phase to G1 may be related to these alterations observed. Only slight increase in content of the alkaline labile sites in DNA and decrease in cAMP content were found in both these cell cultures. Activity of CK in the lymphocytes culture not containing ConA was decreased down to initial level, while in presence of the mitogen the enzymatic activity was increased and within 3 days it reached the level of CK activity in Jurkat cells. The rate of CK relative activity, calculated as CK/cAMP or CK/HK/cAMP ratios for each cell preparation, correlated with DNA biosynthesis rate measured by 3H-thymidine incorporation. The data obtained suggest that these patterns, used in differential diagnosis of human large intestine and gastric tumors, demonstrated also the intensity of tissue proliferation.

[Immunochemical properties of the regulatory subunit of cAMP-dependent protein kinase II]. / Immunokhimicheskie svoistva reguliatornoi sub''edinitsy cAMP-zavisimoi proteinkinazy II tipa.

Immunochemical analysis of the cAMP-dependent protein kinase regulatory subunit type II was performed with the use of two rabbit antisera elicited to a free R-subunit from pig brain and to a RcAMP complex. Quantitative precipitation of the homogeneous antigen revealed six determinants on the R-molecule. Of these at least one is localized in the R-fragment (37 kD), the others--in the N-terminal part of the R-molecule. The antigenic determinants seem to be remoted from the cAMP-binding centers, since the attachment of the affinity purified antibody Fab-fragments to the R-subunit did not influence the cAMP-binding activity of the latter. The antibodies to RcAMP caused dissociation of the holoenzyme. The antibody Fab-fragment binding to the R-subunit prevented its association with the catalytic subunit. The results of immunochemical analysis suggest that the R-subunit adopts different conformations when bound to cAMP or to the catalytic subunit.

Immunofluorescence localization of the regulatory subunit type II of cAMP-dependent protein kinase in PC12 and 3T3 cells in different proliferative states.

Localization of the regulatory subunit of cAMP-dependent protein kinase type II was studied in proliferating and quiescent fibroblasts 3T3 and in a cell line of neural origin pheochromocytoma PC12. In actively proliferating PC12 cells the regulatory subunit was found to be localized in the nucleus. Transition of these cells into a quiescent state was accompanied by a regulatory subunit translocation to the cytoplasm. In 3T3 cells the regulatory subunit was localized in the cytoplasm both in the quiescent and proliferating (though less actively than PC12 cells) states. Similar results were obtained both with monoclonal antibodies and with rabbit monospecific antiserum raised against the regulatory subunit type II from pig brain.

[The enhanced relative intensity of cAMP-dependent protein phosphorylation in stomach tumors]. / Uvelichenie otnositel'noi intensivnosti cAMP-nezavisimogo fosforilirovaniia belkov v opukholiakh zheludka.

The activity of cAMP-dependent histone kinases (HK) and cAMP-independent casein kinases (CK) as well as cAMP level were assessed in gastric mucosa affected by various forms of gastritis as well as in gastric tumor and adjacent normal tissue. CK activity was higher whereas that of HK and cAMP level were lower in tumor and at a distance of 5-20 cm from its edge as compared to gastritis. CK/HK cAMP ratio in adenocarcinoma was 6 times that in normal tissue and 2-2.5 times that in gastritis. The data obtained and those published earlier suggest the relative increase in cAMP-independent protein phosphorylation with respect to its cAMP-dependent counterpart to be characteristic of human tumors.

[Protein kinase activity and cAMP level in gastric mucosa in non-neoplastic diseases]. / Aktivnost' proteinkinaz i soderzhanie cAMP v slizistoi obolochke zheludka pri neopukholevykh zabolevaniiakh.

Activity of cAMP-dependent and -independent protein kinases as well as content of cAMP were studied in biopsy preparations of gastric mucosal membranes obtained from patients with superficial gastritis, erosion, ulcer, adenomatous polyps and ulcer after treatment with laser irradiation. All the patterns studied were similar in preparations of adenomatous polyps and normal mucosal membrane. Activity of cAMP-independent protein kinases was increased under conditions of erosion, ulcer, gastroduodenal reflux and, especially, in ulcer tissue treated with laser. However, the ratio between cAMP-independent and -dependent phosphorylation was increased only in 50% of ulcerous diseases and in gastroduodenal reflux. The equilibrium of cAMP-dependent and -independent phosphorylation was not altered in the other impairments studied even though benign proliferation was stimulated using laser irradiation.

[Changes in protein kinase activity of the skin in cancer]. / Izmenenie aktivnosti proteinkinaz v kozhe pri rake.

The phosphorylating enzymes of human skin were studied in bioptic samples of normal tissue (18 samples) and tumors (21 cases), melanomas and basaliomas, which developed in different regions of head and face. The activity of cAMP-dependent and cAMP-independent protein kinases was tested in skin extracts using histone HI and casein as substrates of phosphorylation, respectively. In most tumors the casein kinase activity was found to be significantly elevated (about 10-fold) as compared with normal counterparts. The histone kinase activity was only slightly elevated in tumors (by 30%). For each bioptic sample the ratio of histone kinase activity versus casein kinase activity was calculated. In normal skin this ratio constituted from 1 to 3.7, while in 90% of samples it was higher than 1.5. In all tumors except one the ratio was decreased down to 0.2-0.9. The effect did not depend upon the type of malignancy and tumor location. The change in the protein kinase ratio is considered to be a specific feature of transformed tissue.

[Structural characteristics and availability of DNA for solvent molecules in nuclei of Physarum polycephalum]. / Strukturnaia kharakteristika i dostupnost' DNK dlia molekul rastvoritelia v iadrakh Physarum polycephalum.

The rate constants of 1H--3H exchange between water and C8H-groups of purinic residues of DNA in solution and in nuclei of synchronous Physarum polycephalum at different phases of the cell cycle were measured. The nuclear membranes and nonhistone proteins were shown not to create additional hindrances and not to diminish the availability of DNA in nuclei for solvent molecules. A small increase of the rate of the 1H--3H exchange between water and the DNA of nuclei upon transition from the S-phase to the late G2-phase seems to reflect the process of chromatin decondensation connected with activation of the transcription and local changes of the secondary structure of DNA at the late G2-phase of the cell cycle.

[Effects of some protein kinases, cyclic nucleotides and specific inhibitors of phosphorylation on the mitotic cycle of Physarum polycephalum]. / Vliianie nekotorykh proteinkinaz, tsiklicheskikh nukleotidov i spetsificheskikh ingibitorov reaktsii fosforilirovaniia na vremia nastupleniia mitoza u miksomitseta Physarum polycephalum.

The true slime mould Physarum polycephalum was treated with various agents by spraying them upon the cell surface 4 hrs before the second synchronous mitosis. The onset of mitosis was considerably approximated after the plasmodium treatment with protein kinases from rat hepatoma or Ph. polycephalum at the late G2 phase. The catalytic and regulatory subunits of cAMP-dependent pig brain protein kinase caused retardation of mitosis, while the holoenzyme, casein kinase and alkaline phosphatase did not affect the timing of mitosis. The cyclic nucleotides and inhibitors of their metabolic enzymes were used to investigate the role of phosphorylation processes in the mitotic cycle.

[Use of immunochemical methods in enzymology]. / Primenenie immunokhimicheskikh metodov v enzimologii.

The binding of antibodies to enzymes-antigens markedly affects the activity and structure of the latters. The mechanisms of activation and inhibition of enzymes by antibodies and the use of immunochemical methods for the study of the active sites structure, conformational changes during interaction with substrates and other ligands and the quaternary structure of enzymes are discussed.

Effect of specific antibodies on D-glyceraldehyde-3-phosphate dehydrogenase.

The inhibition of rat skeletal muscle glyceraldehyde-3-phosphate dehydrogenase by specific antibodies produced in rabbits has been studied. The results suggest that no influence on the enzyme active site is caused by the interaction with antibody, the inhibition being due entirely to the restricted accessibility for substrates of a part of dehydrogenase molecules included in the immune precipitate. Soluble complexes of the enzyme with monovalent Fab antibody fragments retain full catalytic activity. Modification of 8 -SH groups per mole of glyceraldehyde-3-phosphate dehydrogenase with p-chloromercuribenzoate results in no alterations in the quantitative precipitin curve, thus supporting the conclusion about the different localization of species-specific antigenic determinants of the enzyme and its active center. Interaction with monovalent Fab fragments of antibody stabilizes the structure of the dehydrogenase. Eight molar equivalents of Fab fragments almost completely protect the enzyme from cold inactivation in the presence of 0.15 M NaCl. Complex formation with Fab fragments does not prevent, however, the ADP-induced inactivation of the enzyme.