Biochemistry (Moscow) (v.80, #2)

AMP-activated protein kinase: Structure, function, and role in pathological processes by D. S. Novikova; A. V. Garabadzhiu; G. Melino; N. A. Barlev; V. G. Tribulovich (127-144).
Recently, AMP-activated protein kinase (AMPK) has emerged as a key regulator of energy balance at cellular and whole-body levels. Due to the involvement in multiple signaling pathways, AMPK efficiently controls ATP-consuming/ATP-generating processes to maintain energy homeostasis under stress conditions. Loss of the kinase activity or attenuation of its expression leads to a variety of metabolic disorders and increases cancer risk. In this review, we discuss recent findings on the structure of AMPK, its activation mechanisms, as well as the consequences of its targets in regulation of metabolism. Particular attention is given to low-molecular-weight compounds that activate or inhibit AMPK; the perspective of therapeutic use of such modulators in treatment of several common diseases is discussed.
Keywords: AMP-activated protein kinase; energy metabolism; metabolic syndrome; diabetes type 2; cancer; AMPK activators; AMPK inhibitors

Methylation of miRNA genes and oncogenesis by V. I. Loginov; S. V. Rykov; M. V. Fridman; E. A. Braga (145-162).
Interaction between microRNA (miRNA) and messenger RNA of target genes at the posttranscriptional level provides fine-tuned dynamic regulation of cell signaling pathways. Each miRNA can be involved in regulating hundreds of protein-coding genes, and, conversely, a number of different miRNAs usually target a structural gene. Epigenetic gene inactivation associated with methylation of promoter CpG-islands is common to both protein-coding genes and miRNA genes. Here, data on functions of miRNAs in development of tumor-cell phenotype are reviewed. Genomic organization of promoter CpG-islands of the miRNA genes located in inter- and intragenic areas is discussed. The literature and our own results on frequency of CpG-island methylation in miRNA genes from tumors are summarized, and data regarding a link between such modification and changed activity of miRNA genes and, consequently, protein-coding target genes are presented. Moreover, the impact of miRNA gene methylation on key oncogenetic processes as well as affected signaling pathways is discussed.
Keywords: miRNA; CpG-islands; methylation; target genes; epigenetic mechanisms; oncogenesis

Preconditioning (PC) is one of the most effective strategies to reduce the severity of cell damage, in particular of nervous tissue cells. Although PC mechanisms are studied insufficiently, it is clear that proteases are involved in them, but their role has yet been not studied in detail. In this work, some mechanisms of a potential recruiting of proteases in PC are considered. Our attention is mainly focused on the protease families of caspases and cathepsins and on protease receptors. We present evidence that just these proteins are involved in the PC of brain cells. A hypothesis is proposed that secreted cathepsin B is involved in the realization of PC through activation of PAR2 receptor.
Keywords: preconditioning; brain; proteases; caspases; cathepsin; protease receptors (PAR)

Investigation of the chaperonin encoded by gene 146 of bacteriophage EL Pseudomonas aeruginosa that we characterized earlier has been continued. To reveal the mechanism of its functioning, new recombinant substrate proteins, fragments of gene product (gp) 183 containing the lysozyme domain were prepared. Their interaction with gp146 was studied. The influence of the phage chaperonin on the thermal aggregation of one of these gp183 fragments and endolysin (gp188) was investigated in both the presence and the absence of ATP by dynamic light scattering. In the absence of ATP, the phage chaperonin forms stable complexes with substrate proteins, thereby protecting them against thermal aggregation. Experimental data obtained for different substrate proteins are analyzed.
Keywords: phage chaperonin; bacteriophage EL; endolysin; protein aggregation

Features of hydrolysis of specific and nonspecific globular proteins and oligopeptides by antibodies against viral integrase from blood of HIV-infected patients by E. S. Odintsova; P. S. Dmitrenok; S. V. Baranova; A. M. Timofeeva; V. N. Buneva; G. A. Nevinsky (180-201).
It was shown previously that, as differentiated from canonical proteases, abzymes against myelin basic protein (MBP) from blood of patients with multiple sclerosis and systemic lupus erythematosus effectively cleaved only MBP, while antibodies (ABs) against integrase (IN) from blood of HIV-infected patients specifically hydrolyzed only IN. In this work, all sites of effective hydrolysis by anti-IN antibodies (IgG and IgM) of 25-mer oligopeptide (OP25) corresponding to MBP were identified using reversed-phase and thin-layer chromatographies and MALDI mass spectrometry. It was found that amino acid sequences of OP25 and other oligopeptides hydrolyzed by anti-MBP abzymes were partially homologous to some fragments of the full sequence of IN. Sequences of IN oligopeptides cleavable by anti-IN abzymes were homologous to some fragments of MBP, but anti-MBP abzymes could not effectively hydrolyze OPs corresponding to IN. The common features of the cleavage sites of OP25 and other oligopeptides hydrolyzed by anti-MBP and anti-IN abzymes were revealed. The literature data on hydrolysis of specific and nonspecific proteins and oligopeptides by abzymes against different protein antigens were analyzed. Overall, the literature data suggest that short OPs, including OP25, mainly interact with light chains of polyclonal ABs, which had lower affinity and specificity to the substrate than intact ABs. However, it seems that anti-IN ABs are the only one example of abzymes capable of hydrolyzing various oligopeptides with high efficiency (within some hours but not days). Possible reasons for the efficient hydrolysis of foreign oligopeptides by anti-IN abzymes from HIV-infected patients are discussed.
Keywords: HIV-infected patients; catalytic antibodies against viral integrase; integrase; myelin basic protein; hydrolysis of peptides of myelin basic protein

Transcription factor NF-Y belongs to the embryonic stem cell transcription factor circuitry due to its role in the regulation of cell proliferation. We investigated the role of NF-Y in pluripotency maintenance using NT2/D1 cells as one of the best-characterized human embryonal carcinoma cell line. We investigated the efficiency of protein transduction and analyzed the effects of forced expression of short isoform of NF-Y A-subunit (NF-YAs) on NT2/D1 cell growth and expression of SOX2. We found that protein transduction is an efficient method for NF-Y overexpression in NT2/D1 cells. Next, we analyzed the effect of NF-YAs overexpression on NT2/D1 cell viability and detected significant reduction in cell growth. The negative effect of NF-YAs overexpression on NT2/D1 cell pluripotency maintenance was confirmed by the decrease in the level of the pluripotency marker SOX2. Finally, we checked the p53 status and determined that the NF-Y-induced inhibition of NT2/D1 cell growth is p53-independent.
Keywords: NF-Y transcription factor; NT2/D1 cell line; cell growth; SOX2; p53

Reorganization of low-molecular-weight fraction of plasma proteins in the annual cycle of cyprinidae by A. M. Andreeva; N. E. Lamas; M. V. Serebryakova; I. P. Ryabtseva; V. V. Bolshakov (208-218).
Reorganization of the low-molecular-weight fraction of cyprinid plasma was analyzed using various electrophoretic techniques (disc electrophoresis, electrophoresis in polyacrylamide concentration gradient, in polyacrylamide with urea, and in SDS-polyacrylamide). The study revealed coordinated changes in the low-molecular-weight protein fractions with seasonal dynamics and related reproductive rhythms of fishes. We used cultured species of the Cyprinidae family with sequenced genomes for the detection of these interrelations in fresh-water and anadromous cyprinid species. The common features of organization of fish low-molecular-weight plasma protein fractions made it possible to make reliable identification of their proteins. MALDI mass-spectrometry analysis revealed the presence of the same proteins (hemopexin, apolipoproteins, and serpins) in the low-molecular-weight plasma fraction in wild species and cultured species with sequenced genomes (carp, zebrafish). It is found that the proteins of the first two classes are organized as complexes made of protein oligomers. Stoichiometry of these complexes changes in concordance with the seasonal and reproductive rhythms.
Keywords: fish; plasma proteins; mass spectra; MALDI

Y-box binding protein 1 (YB-1) promotes detection of DNA bulky lesions by XPC-HR23B factor by E. E. Fomina; P. E. Pestryakov; E. A. Maltseva; I. O. Petruseva; D. A. Kretov; L. P. Ovchinnikov; O. I. Lavrik (219-227).
The nucleotide excision repair system (NER) is one of the main mechanisms protecting cellular DNA from lesions caused by such significant environmental factors as UV radiation, the influence of polycyclic aromatic hydrocarbons, and medical treatment by several antitumor drugs, e.g. cisplatin. One of the major NER components is XPC-HR23B, the key factor during the damage recognition step of repair. Binding of XPC-HR23B to DNA that contains different bulky lesions impairing the structure of DNA is the basis for the wide substrate specificity of this DNA repair pathway. The multifunctional protein YB-1 among other protein factors has high affinity towards damaged DNA. Involvement of YB-1 in the cellular response to genotoxic stress and its ability to interact with damaged DNA harboring lesions of various origins pinpoint its putative involvement as a modulatory factor in DNA damage recognition and verification steps of NER. In the present work, we assayed functional interactions of protein factors XPC-HR23B and YB-1 upon binding to DNA structures mimicking damaged DNA containing single bulky lesions, as substrates of NER, and bulky lesions combined with abasic sites as an example of clustered lesions. The results indicate that YB-1 and XPC-HR23B stimulate each other in binding to DNA containing a bulky or clustered lesion, which suggests the involvement of YB-1 in the regulation of DNA repair by the NER mechanism.
Keywords: nucleotide excision repair; bulky DNA lesions; clustered DNA lesions; DNA-protein complexes; Y-box binding protein 1 (YB-1); XPC-HR23B

Soluble expression and one-step purification of recombinant mouse interferon-λ3 in Escherichia coli by Y. Q. Wang; M. Zhou; L. M. Zeng; Q. Y. Gao; X. L. Yuan; Y. Li; M. C. Li (228-232).
Interferon (IFN)-λ3, a member of the type III IFN family, is a pleiotropic cytokine that exhibits potent antiproliferative, antiviral, and immunoregulatory activities. For further functional study of IFN-λ3, we developed an efficient procedure that includes cloning, expression, and purification to obtain relatively large quantity of mouse IFN-λ3 fusion protein. The mature IFN-λ3 protein-coding region was cloned into the prokaryotic expression vector pET-44. IFN-λ3 contains a hexahistidine tag at its C-terminus. We used Ni2+-nitrilotriacetic acid agarose-affinity chromatography to purify the expressed soluble protein. The purified IFN-λ3 inhibited significantly IL-13 production in stimulated RAW264.7 macrophages. Our findings show that the production of soluble IFN-λ3 proteins by the pET-44 vector in Escherichia coli is a good alternative for the production of native IFN-λ3 and could be useful for the production of other IFN proteins.
Keywords: interferon-λ3; recombinant protein; Escherichia coli ; pET-44 vector

Enzymatic polymerization of dihydroquercetin using bilirubin oxidase by M. E. Khlupova; I. S. Vasil’eva; G. P. Shumakovich; O. V. Morozova; V. A. Chertkov; A. K. Shestakov; A. V. Kisin; A. I. Yaropolov (233-241).
Dihydroquercetin (or taxifolin) is one of the most famous flavonoids and is abundant in Siberian larch (Larix sibirica). The oxidative polymerization of dihydroquercetin (DHQ) using bilirubin oxidase as a biocatalyst was investigated and some physicochemical properties of the products were studied. DHQ oligomers (oligoDHQ) with molecular mass of 2800 and polydispersity of 8.6 were obtained by enzymatic reaction under optimal conditions. The oligomers appeared to be soluble in dimethylsulfoxide, dimethylformamide, and methanol. UV-visible spectra of oligoDHQ in dimethylsulfoxide indicated the presence of highly conjugated bonds. The synthesized oligoDHQ was also characterized by FTIR and 1H and 13C NMR spectroscopy. Comparison of NMR spectra of oligoDHQ with DHQ monomer and the parent flavonoids revealed irregular structure of a polymer formed via the enzymatic oxidation of DHQ followed by nonselective radical polymerization. As compared with the monomer, oligoDHQ demonstrated higher thermal stability and high antioxidant activity.
Keywords: dihydroquercetin; enzymatic polymerization; bilirubin oxidase; oligomers; 1H and 13C NMR spectra

Cloning and functional expression of a chitinase cDNA from the apple leaf miner moth Lithocolletis ringoniella by Xiao-Jun Fan; Yan-Xia Mi; Hui Ren; Chang Zhang; Yao Li; Xiao-Xiao Xian (242-250).
Insect chitinase plays essential roles in chitin catabolism involved in digestion and molting during insect development. In the current work, we cloned a chitinase cDNA, LrCht5, from the apple leaf miner moth Lithocolletis ringoniella and characterized its amino acid sequence and protein properties. The L. ringoniella chitinase cDNA was 2136 bp in length with an open reading frame of 1737 bp that encodes a polypeptide of 579 amino acid residues with a predicted molecular mass of 64.4 kDa and pI of 5.49. The catalytic domain has several phosphorylation and glycosylation sites. The recombinant LrCht5 was expressed in Escherichia coli and the Spodoptera frugiperda cell line Sf9, and the LrCht5 expressed in insect cells exhibited chitinolytic activity. LrCht5 was most stable at pH 6.0 and 45°C. This work has potential application in the development of novel and more specific synthetic chitinase inhibitors for use as bioinsecticides.
Keywords: Lithocolletis ringoniella ; chitinase; RACE; enzyme activity