Mechanisms of Brain Glucocorticoid Resistance in Stress-Induced Psychopathologies.

Exposure to stress activates the hypothalamic-pituitary-adrenal axis and leads to increased levels of glucocorticoid (GC) hormones. Prolonged elevation of GC levels causes neuronal dysfunction, decreases the density of synapses, and impairs neuronal plasticity. Decreased sensitivity to glucocorticoids (glucocorticoid resistance) that develops as a result of chronic stress is one of the characteristic features of stress-induced psychopathologies. In this article, we reviewed the published data on proposed molecular mechanisms that contribute to the development of glucocorticoid resistance in brain, including changes in the expression of the glucocorticoid receptor (GR) gene, biosynthesis of GR isoforms, and GR posttranslational modifications. We also present data on alterations in the expression of the FKBP5 gene encoding the main component of cell ultra-short negative feedback loop of GC signaling regulation. Recent discoveries on stress- and GR-induced changes in epigenetic modification patterns as well as normalizing action of antidepressants are discussed. GR and FKBP5 gene polymorphisms associated with stress-induced psychopathologies are described, and their role in glucocorticoid resistance is discussed.

Hidden heterogeneity of transcription factor binding sites: A case study of SF-1.

Steroidogenic factor 1 (SF-1) belongs to a small group of the transcription factors that bind DNA only as a monomer. Three different approaches-Sitecon, SiteGA, and oPWM-constructed using the same training sample of experimentally confirmed SF-1 binding sites have been used to recognize these sites. The appropriate prediction thresholds for recognition models have been selected. Namely, the thresholds concordant by false positive or negative rates for various methods were used to optimize the discrimination of steroidogenic gene promoters from the datasets of non-specific promoters. After experimental verification, the models were used to analyze the ChIP-seq data for SF-1. It has been shown that the sets of sites recognized by different models overlap only partially and that an integration of these models allows for identification of SF-1 sites in up to 80% of the ChIP-seq loci. The structures of the sites detected using the three recognition models in the ChIP-seq peaks falling within the [-5000, +5000] region relative to the transcription start sites (TSS) extracted from the FANTOM5 project have been analyzed. The MATLIGN classified the frequency matrices for the sites predicted by oPWM, Sitecon, and SiteGA into two groups. The first group is described by oPWM/Sitecon and the second, by SiteGA. Gene ontology (GO) analysis has been used to clarify the differences between the sets of genes carrying different variants of SF-1 binding sites. Although this analysis in general revealed a considerable overlap in GO terms for the genes carrying the binding sites predicted by oPWM, Sitecon, or SiteGA, only the last method elicited notable trend to terms related to negative regulation and apoptosis. The results suggest that the SF-1 binding sites are different in both their structure and the functional annotation of the set of target genes correspond to the predictions by oPWM+Sitecon and SiteGA. Further application of Homer software for de novo identification of enriched motifs in ChIP-Seq data for SF-1ChIP-seq dataset gave the data similar to oPWM+Sitecon.

Bioinformatical and experimental approaches to investigation of transcription factor binding sites in vertebrate genes.

The development of computer-assisted methods for transcription factor binding sites (TFBS) recognition is necessary for study the DNA regulatory transcription code. There are a great number of experimental methods that enable TFBS identification in genome sequences. The experimental data can be used to elaborate multiple computer approaches to recognition of TFBS, each of which has its own advantages and limitations. A short review of the characteristics of computer methods of TFBS prediction based on various principles is presented. Methods used for experimental monitoring of predicted sites are analyzed. Data concerning DNA regulatory potential and its realization at the chromatin level, obtained using these methods, are discussed along with approaches to recognition of target genes of certain transcription factors in the genome sequences.

[Regulation of eukaryotic gene transcription: description in the TRRD database]. / Reguliatsiia transkriptsii genov éukariot: opisanie v baze dannykh TRDD.

The structure of the Transcription Regulatory Regions Database (TRRD) and the principles of considering transcription regulation of eukaryotic genes in TRRD are concerned. Formal description of the structural and functional organization of the regulatory gene regions is illustrated with examples. By now, TRRD is based on 3500 original works and contains data on transcription regulation of more than 1100 genes known to possess more than 5000 transcription factor-binding sites and about 1600 regulatory elements (promoters, enhancers, silencers). TRRD is available at http://www.bionet.nsc.ru/trrd/.

Point mutations within 663-666 bp of intron 6 of the human TDO2 gene, associated with a number of psychiatric disorders, damage the YY-1 transcription factor binding site.

Single base mutations G-->A at position 663 and G-->T at position 666 of intron 6 of the human tryptophan oxygenase gene (TDO2) are associated with a variety of psychiatric disorders [Comings, D.E. et al. (1996) Pharmacogenetics 6, 307-318]. Binding of rat liver nuclear extract proteins to synthetic double-strand oligonucleotides corresponding to three allelic states of the region between 651 bp and 680 bp of human TDO2 intron 6 has been studied by gel shift assay. It has been demonstrated that to each allelic state of the region there corresponds a specific set of proteins that interacts with it. With the aid of computer analysis and using specific anti-YY-1 antibodies it has been shown that both mutations damage the YY-1 transcription factor binding site.

[The characteristics of the development of gallbladder and biliary tract pathology under the influence of vibration]. / Osobennosti formirovaniia patologii zhelchnogo puzyria i zhelchevyvodiashchikh putei pod vliianiem vibratsii.

The examination of 86 helicopter pilots has shown that their exposure to vibration leads to biliary and gallbladder damage which aggravates with longer service. As indicated by spectroscopy and gas-liquid chromatography, vibration affects colloid-osmotic properties of bile: molecules grow in size, bile acids retention becomes longer.

[The organizational and methodological aspects of flight medicine expertise in cardiovascular diseases]. / Organizatsionno-metodicheskie aspekty vrachebno-letnoi ékspertizy pri zabolevaniiakh serdechno-sosudistoi sistemy.

Among diseases causing pilot disqualification ahead of time the cardiovascular disorders amount to 60 percent. In this connection there has been generalized the experience of examining the Armed Forces Aviation pilots with cardiovascular disorders beginning from 1979 when by the order of the Ministry of Defence N 220 the Regulations of Aeromedical Examination of pilots have been come into force. The features of examining the pilots with cardiovascular disorders are presented. The present-day methods for the instrumental examination which have been tested in cardiology are systematized in an effort to use them during aeromedical examinations of the pilots. The algorithm of the examined pilots with cardiovascular disorders is set. For the first time the three main groups of approaches to the appraisal of partial or complete loss of the work capacity with known result of diseases. The proposed organization-and-methodologic approach to medical examination of the flying personnel with consideration for the features of stage diagnostics of cardiovascular disorders, individual assessment of their manifestations enables one to handle more qualitatively the aeromedical examination issues with the aim of maintaining the professional working capacity.

Nucleotide sequence of a fragment of the rat tryptophan oxygenase gene showing high affinity to glucocorticoid receptor in vitro.

A nucleotide sequence (3.2 kb) of a DNA region located approximately between introns 4 and 7 of the rat tryptophan oxygenase gene was determined. Using filter binding studies and monoclonal antibodies against the glucocorticoid receptor a high affinity binding of this region to the glucocorticoid receptor was demonstrated.

[Glycemia as a risk factor of reduced tolerance of hypoxic hypoxia in flight personnel]. / Glikemiia kak faktor riska ponizhennoi perenosimosti gipoksicheskoi gipoksii u letnogo sostava.

The glycemic level was measured in 61 people exposed to hypoxic hypoxia. Three major types of glycemic responses were identified: type I--no change (15.79%); type II--hypoglycemia (49.12%), and type III--hyperglycemia (35.09%). The subjects with a low resistance to hypoxic hypoxia typically showed a low glycemic level (57.5 +/- 2.5 mg%. P < 0.05). It is suggested that three types of glycemic responses to hypoxia reflect three major pathways of biochemical adaptation of the body. It is recommended to study hormonal changes in people with hyperglycemic responses to hypoxia. This will help determine hormonal levels responsible for hyperglycemia and, consequently, develop methods of early detection of susceptibility to cardiovascular diseases and diabetes mellitus. This approach may contribute to medical expertise and rehabilitation of the flying personnel.

[Identification of the glucocorticoid receptor binding site at the 5'-flanking region of mouse metallothionein I gene: the effect of base substitutions on binding efficiency]. / Identifikatsiia uchastka sviazyvaniia gliukokortikoid-retseptornogo kompleksa v 5'-flankiruiushchem raione gena metallotioneina I myshi: vliianie nukleotidnykh zamen na éffektivnost' sviazyvaniia.

Interaction of highly purified glucocorticoid receptor complex (GIRC) with synthetic DNA-fragment of mouse metallotionein 1 gene promoter from -209 to -252 b.p. (MTwt) was investigated. By means of nitrocellulose filter binding assay this fragment was shown to contain specific GIRC-binding site. In order to analyse the fine structure of the site, two variants of this DNA-fragment were synthesized and used in gel retardation assay. GIRC specific binding was shown to retain throughout interaction with the fragment in which all base pairs in the surroundings of generally accepted GIRC-binding site consensus G--ACA---TGTTCT C--TGT---ACAAGA were substituted by means of transitions, but it was weaker than the GIRC-binding with MTwt, where the mentioned consensus was situated in the natural surroundings. Complete loss of the GIRC-binding ability was observed when five CG pairs were substituted by AT ones. Two of the CG pairs belonged to the mentioned consensus. Comparison of the data obtained with results of computer analysis allows to consider the consensus as a "core" of GIRC-binding site, flanked with additional elements, interacting with GIRC.