Biochemistry (Moscow) (v.81, #2)
Cellular energetics as a target for tumor cell elimination by P. V. Maximchik; A. V. Kulikov; B. D. Zhivotovsky; V. G. Gogvadze (65-79).
Investigation of cancer cell metabolism has revealed variability of the metabolic profiles among different types of tumors. According to the most classical model of cancer bioenergetics, malignant cells primarily use glycolysis as the major metabolic pathway and produce large quantities of lactate with suppressed oxidative phosphorylation even in the presence of ample oxygen. This is referred to as aerobic glycolysis, or the Warburg effect. However, a growing number of recent studies provide evidence that not all cancer cells depend on glycolysis, and, moreover, oxidative phosphorylation is essential for tumorigenesis. Thus, it is necessary to consider distinctive patterns of cancer metabolism in each specific case. Chemoresistance of cancer cells is associated with decreased sensitivity to different types of antitumor agents. Stimulation of apoptosis is a major strategy for elimination of cancer cells, and therefore activation of mitochondrial functions with direct impact on mitochondria to destabilize them appears to be an important approach to the induction of cell death. Consequently, the design of combination therapies using acclaimed cytotoxic agents directed to induction of apoptosis and metabolic agents affecting cancer cell bioenergetics are prospective strategies for antineoplastic therapy.
Keywords: tumor cells; bioenergetics; mitochondria; Warburg effect; glycolysis
Interleukins 1 and 6 as main mediators of inflammation and cancer by O. S. Dmitrieva; I. P. Shilovskiy; M. R. Khaitov; S. I. Grivennikov (80-90).
The idea of a potential link between cancer and inflammation was first proposed by R. Virchow in the nineteenth century. However, clear evidence regarding a key role of inflammation in oncogenesis appeared only during the last decade. Now the tumor microenvironment is commonly considered as an obligatory and significant component of almost all types of cancer, and the cells infiltrating such microenvironment are a source of inflammatory cytokines. Such cytokines play a key role in regulating inflammation during both normal immune response and developing cancer. In this review, we explore the role of two inflammatory cytokines interleukin 1 and interleukin 6 in cancer development. These cytokines have pleiotropic effects on various cell types in the tumor microenvironment, particularly being able to regulate pro-oncogenic transcription factors NF-κB and STAT3. For this reason, such cytokines influence key parameters of oncogenesis, increasing cell resistance to apoptosis, proliferation of cancer cells, angiogenesis, invasion and malignancy as well as the ability of tumor cells to respond to anticancer therapy. Here we summarize novel experimental data regarding mechanisms underlying the interaction between chronic inflammation and malignant neoplasms.
Keywords: inflammation; cancer; cytokines; interleukin 1; interleukin 6; NF-κB; tumor microenvironment
Problems of glioblastoma multiforme drug resistance by A. A. Stavrovskaya; S. S. Shushanov; E. Yu. Rybalkina (91-100).
Glioblastoma multiforme (GBL) is the most common and aggressive brain neoplasm. A standard therapeutic approach for GBL involves combination therapy consisting of surgery, radiotherapy, and chemotherapy. The latter is based on temozolomide (TMZ). However, even by applying such a radical treatment strategy, the mean patient survival time is only 14.6 months. Here we review the molecular mechanisms underlying the resistance of GBL cells to TMZ including genetic and epigenetic mechanisms. Present data regarding a role for genes and proteins MGMT, IDH1/2, YB-1, MELK, MVP/LRP, MDR1 (ABCB1), and genes encoding other ABC transporters as well as Akt3 kinase in developing resistance of GBL to TMZ are discussed. Some epigenetic regulators of resistance to TMZ such as microRNA and EZH2 are reviewed.
Keywords: glioblastoma; temozolomide; drug resistance; YB-1 gene; microRNA
Mitochondrial genome structure of photosynthetic eukaryotes by N. P. Yurina; M. S. Odintsova (101-113).
Current ideas of plant mitochondrial genome organization are presented. Data on the size and structural organization of mtDNA, gene content, and peculiarities are summarized. Special emphasis is given to characteristic features of the mitochondrial genomes of land plants and photosynthetic algae that distinguish them from the mitochondrial genomes of other eukaryotes. The data published before the end of 2014 are reviewed.
Keywords: mitochondria; photosynthetic eukaryotes; mitochondrial genome
Activity of tissue factor in microparticles produced in vitro by endothelial cells, monocytes, granulocytes, and platelets by S. G. Khaspekova; O. A. Antonova; O. N. Shustova; V. V. Yakushkin; N. V. Golubeva; E. V. Titaeva; A. B. Dobrovolsky; A. V. Mazurov (114-121).
Activity of tissue factor (TF) in membrane microparticles (MPs) produced in vitro by endothelial cells (ECs), monocytes, THP-1 monocytic cells, granulocytes, and platelets was investigated. ECs were isolated from human umbilical vein, and monocytes, granulocytes, and platelets–from the blood of healthy donors. ECs, monocytes, and THP-1 cells were activated by bacterial lipopolysaccharide, granulocytes–by lipopolysaccharide or phorbol myristate acetate, and platelets - by SFLLRN, thrombin receptor-activating peptide. MPs were sedimented from the culture medium or supernatant of activated cells at 20,000g for 30 min. Coagulation activity of MPs was analyzed in a modified recalcification assay by assessing their effects on coagulation of donor plasma depleted of endogenous MPs (by centrifuging at 20,000g for 90 min). MPs from all cell types accelerated plasma coagulation. Antibodies blocking TF activity prolonged coagulation lagphase in the presence of MPs from ECs, monocytes, and THP-1 cells (by 2.7-, 2.0-, and 1.8-fold, respectively), but did not influence coagulation in the presence of MPs from granulocytes and platelets. In accordance with these data, TF activity measured by its ability to activate factor X was found in MPs from ECs, monocytes, and THP-1 cells, but not in MPs from granulocytes and platelets. The data obtained indicate that active TF is present in MPs produced in vitro by ECs, monocytes, and THP-1 cells, but not in MPs derived from granulocytes and platelets.
Keywords: membrane microparticles; coagulation; tissue factor; endothelial cells; monocytes; granulocytes; platelets
Structure, chaperone activity, and aggregation of wild-type and R12C mutant αB-crystallins in the presence of thermal stress and calcium ion – Implications for role of calcium in cataract pathogenesis by M. Ragerdi Kashani; R. Yousefi; M. Akbarian; M. M. Alavianmehr; Y. Ghasemi (122-134).
The current study was performed with the aim to evaluate the chaperoning ability, structural features, and aggregation propensity of wild-type and R12C mutant αB-crystallins (αB-Cry) under thermal stress and in the presence of calcium ion. The results of different spectroscopic analyses suggest that wild-type and mutant αB-Cry have dissimilar secondary and tertiary structures. Moreover, αB-Cry indicates slightly improved chaperone activity upon the R12C mutation. Thermal stress and calcium, respectively, enhance and reduce the extent of solvent-exposed hydrophobic surfaces accompanying formation of ordered and non-ordered aggregate entities in both proteins. Compared to the wild-type protein, the R12C mutant counterpart shows significant resistance against thermal and calcium-induced aggregation. In addition, in the presence of calcium, significant structural variation was accompanied by reduction in the solvent-exposed hydrophobic patches and attenuation of chaperone activity in both proteins. Additionally, gel mobility shift assay indicates the intrinsic propensity of R12C mutant αB-Cry for disulfide bridge-mediated protein dimerization. Overall, the results of this study are of high significance for understanding the molecular details of different factors that are involved in the pathomechanism of cataract disorders.
Keywords: αB-crystallin; R12C mutation; chaperone; thermal stress; aggregation
Interaction between fibrinogen and insulin-like growth factor-binding protein-1 in human plasma under physiological conditions by N. Gligorijević; O. Nedić (135-140).
Fibrinogen is a plasma glycoprotein and one of the principle participants in blood coagulation. It interacts with many proteins during formation of a blood clot, including insulin-like growth factors (IGFs) and their binding proteins (IGFBP). Fibrinogen complexes were found as minor fractions in fibrinogen preparations independently of the coagulation process, and their presence influences the kinetics of polymerization. The idea of this work was to investigate whether fibrinogen in human plasma interacts with IGFBPs independently of the tissue injury or coagulation process. The results have shown that fibrinogen forms complexes with IGFBP-1 under physiological conditions. Several experimental approaches have confirmed that complexes are co-isolated with fibrinogen from plasma, they are relatively stable, and they appear as a general feature of human plasma. Several other experiments excluded the possibility that alpha-2 macroglobulin/IGFBP-1 complexes or IGFBP-1 oligomers contributed to IGFBP-1 immunoreactivity. The role of fibrinogen/IGFBP-1 complexes is still unknown. Further investigation in individuals expressing both impaired glucose control and coagulopathy could contribute to identification and understanding of their possible physiological role.
Keywords: fibrinogen; IGFBP-1; human plasma; complexes; complex isolation
Plant DNA methyltransferase genes: Multiplicity, expression, methylation patterns by V. V. Ashapkin; L. I. Kutueva; B. F. Vanyushin (141-151).
Expression and methylation patterns of genes encoding DNA methyltransferases and their functionally related proteins were studied in organs of Arabidopsis thaliana plants. Genes coding for the major maintenance-type DNA methyltransferases, MET1 and CMT3, and the major de novo-type DNA methyltransferase, DRM2, are actively expressed in all organs. Similar constitutively active expression was observed for genes encoding their functionally related proteins, a histone H3K9 methyltransferase KYP and a catalytically non-active protein DRM3. Expression of the MET1 and CMT3 genes is significantly lower in developing endosperm compared with embryo. Vice versa, expression of the MET2a, MET2b, MET3, and CMT2 genes in endosperm is much more active compared with embryo. A special maintenance DNA methylation system seems to operate in endosperm. The DNMT2 and N6AMT genes encoding putative methyltransferases are constitutively expressed at low levels. CMT1 and DRM1 genes are expressed rather weakly in all investigated organs. Most of the studied genes have methylation patterns conforming to the “body-methylated gene” prototype. A peculiar feature of the MET family genes is methylation at all three possible site types (CG, CHG, and CHH). The most weakly expressed among genes of their respective families, CMT1 and DRM1, are practically unmethylated. The MET3 and N6AMT genes have unusual methylation patterns, promoter region, and most of the gene body devoid of any methylation, and the 3'-end proximal part of the gene body is highly methylated.
Keywords: DNA methylation; DNA methyltransferase; gene expression; quantitative PCR; bisulfite sequencing; Arabidopsis thaliana
Express sequence tag analysis – Identification of anseriformes trypsin genes from full-length cDNA library of the duck (Anas platyrhynchos) and characterization of their structure and function by Haining Yu; Shasha Cai; Jiuxiang Gao; Chen Wang; Xue Qiao; Hui Wang; Lan Feng; Yipeng Wang (152-162).
Trypsins are key proteins important in animal protein digestion by breaking down the peptide bonds on the carboxyl side of lysine and arginine residues, hence it has been used widely in various biotechnological processes. In the current study, a full-length cDNA library with capacity of 5·105 CFU/ml from the duck (Anas platyrhynchos) was constructed. Using express sequence tag (EST) sequencing, genes coding two trypsins were identified and two full-length trypsin cDNAs were then obtained by rapid-amplification of cDNA end (RACE)-PCR. Using Blast, they were classified into the trypsin I and II subfamilies, but both encoded a signal peptide, an activation peptide, and a 223-a.a. mature protein located in the C-terminus. The two deduced mature proteins were designated as trypsin-IAP and trypsin-IIAP, and their theoretical isoelectric points (pI) and molecular weights (MW) were 7.99/23466.4 Da and 4.65/24066.0 Da, respectively. Molecular characterizations of genes were further performed by detailed bioinformatics analysis. Phylogenetic analysis revealed that trypsin-IIAP has an evolution pattern distinct from trypsin-IAP, suggesting its evolutionary advantage. Then the duck trypsin-IIAP was expressed in an Escherichia coli system, and its kinetic parameters were measured. The three dimensional structures of trypsin-IAP and trypsin-IIAP were predicted by homology modeling, and the conserved residues required for functionality were identified. Two loops controlling the specificity of the trypsin and the substrate-binding pocket represented in the model are almost identical in primary sequences and backbone tertiary structures of the trypsin families.
Keywords: Anseriformes; Anas platyrhynchos ; trypsin; molecular cloning; expression; structure and function
Role of endonuclease G in exogenous DNA stability in HeLa cells by V. Misic; M. El-Mogy; Y. Haj-Ahmad (163-175).
Endonuclease G (EndoG) is a well-conserved mitochondrial-nuclear nuclease with dual lethal and vital roles in the cell. The aim of our study was to examine whether EndoG exerts its nuclease activity on exogenous DNA substrates such as plasmid DNA (pDNA), considering their importance in gene therapy applications. The effects of EndoG knockdown on pDNA stability and levels of encoded reporter gene expression were evaluated in the cervical carcinoma HeLa cells. Transfection of pDNA vectors encoding short-hairpin RNAs (shRNAs) reduced levels of EndoG mRNA in HeLa cells. In physiological circumstances, EndoG knockdown did not have an effect on the stability of pDNA or the levels of encoded transgene expression as measured over a four-day time course. However, when endogenous expression of EndoG was induced by an extrinsic stimulus, targeting of EndoG by shRNA improved the perceived stability and transgene expression of pDNA vectors. Therefore, EndoG is not a mediator of exogenous DNA clearance, but in non-physiological circumstances, it may nonspecifically cleave intracellular DNA regardless of its origin. These findings make it unlikely that targeting of EndoG is a viable strategy for improving the duration and level of transgene expression from nonviral DNA vectors in gene therapy efforts.
Keywords: EndoG; HeLa cells; plasmids; shRNAs; silencing; transfection
3-Acetyl-chlorophyll formation in light-harvesting complexes of purple bacteria by chemical oxidation by Z. K. Makhneva; A. A. Ashikhmin; M. A. Bolshakov; A. A. Moskalenko (176-186).
Oxidation of bacteriochlorophyll (BChl) with potassium ferricyanide in membranes and LH2 complexes (carotenoid-less and control samples) from the purple bacteria Allochromatium minutissimum and Rhodobacter sphaeroides as well as BChl photobleaching in a model system have been studied. The oxidation of BChl depended on the type of bacteria. BChl850 was rapidly oxidized in samples from Alc. minutissimum, and BChl800 and BChl850 were slowly oxidized in samples from Rb. sphaeroides. The carotenoids were not involved in protecting BChl from chemical oxidation in the lightharvesting complexes. The appearance of BChl oxidation product was registered in the absorption spectra (absorption maximum about 700 nm) and by HPLC analysis. The oxidized BChl was identified as 3-acetyl-chlorophyll. It differed from BChl by the presence of a double bond in pyrrole ring II at the 7-8 position. The extinction coefficient of 3-acetyl-chlorophyll was about 10 times less than that of BChl850 in the LH2 complex from Alc. minutissimum. In the BChl → 3-acetylchlorophyll transition, the binding constant of the latter with LH2 complex as compared with that of BChl did not change dramatically, as indicated by: (i) preserved electrophoretic mobility of the complex; (ii) the presence of 3-acetyl-chlorophyll in the complex after separation; (iii) the presence of a 3-acetyl-chlorophyll CD signal that was proportional to its absorption spectrum.
Keywords: photosynthetic bacteria; photosynthesis; LH2 complex; potassium ferricyanide; 3-acetyl-chlorophyll