Epigenetic modifications are responsible for the modulation of gene expression without affecting the nucleotide sequence. The observed changes in transcriptional activity of genes in tumor tissue compared to normal tissue, are often the result of DNA methylation within the promoter sequences of these genes. This modification by attaching methyl groups to cytosines within CpG islands results in silencing of transcriptional activity of the gene, which in the case of tumor suppressor genes is manifested by abnormal cell cycle, proliferation and excessive destabilization of the repair processes. Further studies of epigenetic modifications will allow a better understanding of mechanisms of their action, including the interdependence between DNA methylation and activity of proteins crucial to the structure of chromatin and gene activity. Wider knowledge of epigenetic mechanisms involved in the process of malignant transformation and pharmacological regulation of the degree of DNA methylation provides an opportunity to improve the therapeutic actions in the fight against cancer.
Introduction: Peroxiredoxin 6 (Prdx6) is a bifunctional protein and a unique 1-Cys Prdx of the peroxiredoxin family. The expression and regulation of Prdx6 are implicated in numerous physiological and pathological processes.
Material and Methods: Eight stepwise truncated DNA fragments obtained from the 5′-flank region of the Prdx6 gene were prepared and subcloned into the pSEAP2-Enhancer vectors. To investigate the transcriptional activity of the truncated DNA fragments, the recombinant plasmids were transfected into the COS-1 cells and the transcriptional activity was measured via assaying the expression of the reporter gene of the secreted alkaline phosphatase.
Results: A 3.4 kb 5′-upstream flank region of the Prdx6 gene was cloned and sequenced. The region from −108 nt to −36 nt of the 5′-flanking region of the Prdx6 gene contained basal transcriptional activity.
Conclusion: This result provides the basis for further studies on the gene regulation of the Prdx6-mediated biological processes and on screening for the transacting factors that interact with cis-acting elements of the Prdx6 gene promoter.
Objective. The aim of the present study was to investigate the transcriptional activity of the GLP-1R, DPP-4, SGLT-1, INSR, and IGF-1R genes in GALT cells of rats with streptozotocin-induced diabetes in both untreated and treated with pentoxifylline, as a non-specific blocker of TNF-α.
Methods. The expression of GLP-1R, DPP-4, SGLT-1, INSR, and IGF-1R genes in GALT cells of rats was studied by real time quantitative polymerase chain reaction.
Results. It was shown that the development of diabetes was accompanied by the decrease of GLP-1R and an increase of DPP-4 genes expression in rat ileum. The administration of pentoxifyl-line to diabetic animals led to an increase in the transcriptional activity of GLP-1R on the 4th week and decrease in transcriptional activity of DPP-4 on the 2nd and 4th weeks of the experiment. An increase in the normalized expression of SGLT-1 on the 4th week of the experimental diabetes was also noted, while the administration of pentoxifylline to diabetic animals did not lead to significant changes in this index. The transcriptional activity of the INSR and IGF-1R genes was reduced in diabetic rats and the administration of the non-specific TNF-α blocker – pentoxifylline led to a significant increase only for INSR gene in animals on the 4th week of the experimental diabetes.
Conclusions. The expression of incretins, glucose transporters, and pro-inflammatory cytokines (e.g. TNF-α) in immune cells may be used as markers of several autoimmune pathologies progression such as type 1 diabetes due to their effect on the balance of pro- and anti-inflammatory factors.
»orphan« diseases in search of clinical consideration: coronary syndromes X and Y. Cardiovasc Ther 2012; 30(2): e58–e65. 23. Dabek J, Kulach A, Wilczok T, Mazurek U, Jakubowski D, Gasior Z. TranscriptionalActivity of Genes Encoding Interferong (IFNg) and its Receptor Assessed in Peripheral Blood Mononuclear Cells in Patients with Cardiac Syndrome X. Inflammation 2007; 30(3–4): 125–9. 24. Livak KJ, Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2− DDCT method. Methods 2001; 25(4): 402–8. 25. Pekdemir H, Cin VG, Çiçek D
In this study the sequences of the long terminal repeat (LTR) of field isolates of the bovine leukaemia virus (BLV) were analysed. These isolates came from emerging cases of BLV infection in cattle from herds having BLV-free status. We found several sequence variations within regulatory motifs in the LTRs like GRE, DAS and interferon binding site. These mutations can possibly affect transcriptional activity of the virus, leading to its silencing.
Allelic and haplotypic variations at 27 SNP sites identified in four CpG islands of OAS1 were described in a group of Anglo-Arabian and Hucul horses. Variation in the type of less frequent alleles was the source of variability among breeds. A number of putative LD blocks were identified which could be used to study changes in the genetic structure between generations of both breeds concerning susceptibility to flaviviral infections. Some of the identified SNPs may have an impact on the transcriptional activity of OAS1 or could lead to amino acid substitution influencing proper function of OAS1 enzyme. In the light of recent studies, the described genetic variability of investigated CpG islands might be important in view of the effectiveness of viral incorporation into the host genome.
Successful cloning of animals by somatic cell nuclear transfer (SCNT) requires epigenetic transcriptional reprogramming of the differentiated state of the donor cell nucleus to a totipotent embryonic ground state. It means that the donor nuclei must cease its own program of gene expression and restore a particular program of the embryonic genome expression regulation that is necessary for normal development. Transcriptional activity of somatic cell-derived nuclear genome during embryo pre- and postimplantation development as well as foetogenesis is correlated with the frequencies for spatial remodeling of chromatin architecture and reprogramming of cellular epigenetic memory. This former and this latter process include such covalent modifications as demethylation/re-methylation of DNA cytosine residues and acetylation/deacetylation as well as demethylation/re-methylation of lysine residues of nucleosomal core-derived histones H3 and H4. The main cause of low SCNT efficiency in mammals turns out to be an incomplete reprogramming of transcriptional activity for donor cell-descended genes. It has been ascertained that somatic cell nuclei should undergo the wide DNA cytosine residue demethylation changes throughout the early development of cloned embryos to reset their own overall epigenetic and parental genomic imprinting memories that have been established by re-methylation of the nuclear donor cell-inherited genome during specific pathways of somatic and germ cell lineage differentiation. A more extensive understanding of the molecular mechanisms and recognition of determinants for epigenetic transcriptional reprogrammability of somatic cell nuclear genome will be helpful to solve the problems resulting from unsatisfactory SCNT effectiveness and open new possibilities for common application of this technology in transgenic research focused on human biomedicine.
IL-18 Gene Promoter Region 607C/A Polymorphism in HIV-1 Infected North Indian Population
Several host genetic factors play an important role in susceptibility to human immunodeficiency virus type 1 (HIV-1) infection and in its progression to acquired immune deficiency syndrome (AIDS). The interleukin-18 (IL-18) is a multifunctional proinflammatory cytokine that regulates immune responses and plays a pathogenic role in HIV-1 infection by enhancing viral replication. Single nucleotide polymorphisms (SNPs) in the IL-18 gene promoter region may lead to altered transcriptional activity and IL-18 production, and may account for variation in the risk of HIV-1 infection. We have investigated the association between IL-18 promoter polymorphism -607C>A and HIV-1 infection through a case-control study of 500 patients with HIV-1/AIDS and an equal number of age and sex matched controls in a north Indian population. Genotyping using sequence specific primer-polymerase chain reaction (SSP-PCR) showed a statistically significant reduced risk of HIV-1 infection for the A>A genotype [odds ratio (OR) = 0.57, 95% confidence interval (95% CI) = 0.33-0.98, p = 0.040], but not for the C>A genotype (OR = 0.87, 95% CI = 0.66-1.14, p = 0.321). We concluded that the -607A allele of the IL-18 gene promoter polymorphism may play a protective role against the progression of HIV-1 infection in this population.
Objective. Thyroid hormones have important actions in the adult brain. They regulate genes expression in myelination, differentiation of neuronal and glial cells, and neuronal viability and function.
Methods. We used the pathway-specific real-time PCR array (Neurotrophins and Receptors RT2 Profiler PCR Array, QIAGEN, Germany) to identify and verify nerve impulse transmission pathway-focused genes expression in peripheral white blood cells of patients with postoperative hypothyroidism, hypothyroidism as a result of autoimmune thyroiditis (AIT) and AIT with elevated serum an anti-thyroglobulin (anti-Tg) and anti-thyroid peroxidase (anti-TPO) antibodies.
Results. It was shown that patients with postoperative hypothyroidism and hypothyroidism resulting from AIT had significantly lower expression of BDNF and CBLN1. In patients with AIT with elevated serum anti-Tg and anti-TPO antibodies, the expression of GDNF was significantly down-regulated and the expression of PNOC was up-regulated. The expression levels of MEF2C and NTSR1 were decreased in the group of patients with postoperative hypothyroidism and AIT, correspondingly.
Conclusions. The results of this study demonstrate that AIT and hypothyroidism can affect the expression of mRNA nerve impulse transmission genes in gene specific manner and that these changes in gene expressions can be playing a role in the development of neurological complications associated with thyroid pathology. Detection of the transcriptional activity of nerve impulse transmission genes in peripheral white blood cells can be used as an important minimally invasive prognostic marker of the risk for developing neurological complications comorbid with thyroid pathology.
Background: Previous study suggests that high mobility group box 1 (HMGB1) can be a potential late inflammatory mediator. However, whether heat shock factor 1 (HSF1) regulate HMGB1 expression via binding to heat shock element (HSE) is not known.
Objective:We investigated the role of HSF1 in the transcriptional regulation of HMGB1 protein.
Methods: A probe that included HMGB1 promoter region containing HSE was synthesized for electrophoretic mobility shift assay (EMSA) to determine the binding of HSF1 and HSE in the promoter region of HMGB1 gene. Mutant mouse HMGB1 promoter was prepared by PCR amplification on a template of wild-type plasmid DNA with site-directed mutant primers. The mutant DNA fragments were also inserted into a corresponding plasmid. In addition, luciferase reporter plasmids of HMGB1 promoter were constructed to transfect RAW264.7 cells. After that, luciferase activity was measured to assay the effects of the HSF1 transfection on the promoter activity.
Results: EMSA result showed a retardation strap after the coculture of biotin labeled HSF1 binding fragment and nuclear protein extracts. The retardation phenomenon could be competed by unlabeled probe and not by unlabeled mutant probe. A super retardation strap was present after adding HSF1 monoclonal antibody. After the HSE core sites was mutated, the relative luciferase activity of the mutant plasmid decreased by 4.26 folds compared with that in the wild-type (23.54±1.68 vs.100.25±3.26, p <0.01). EMSA assay also confirmed that there were HSF1 binding sites HSE (-668bp~-651bp) in the promoter region of HMGB1. The mutation of the core base of HSF1 binding sites decreased the transcriptional activity of HMGB1.
Conclusion: HSF1 can bind to the promoter region HSE (-668bp~-651bp) of HMGB1, which down-regulates the expression of HMGB1.