Overexpression of microRNAs miR-25-3p, miR-185-5p and miR-132-3p in Late Onset Fetal Growth Restriction, Validation of Results and Study of the Biochemical Pathways Involved.

In a prospective study, 48 fetuses were evaluated with Doppler ultrasound after 34 weeks and classified, according to the cerebroplacental ratio (CPR) and estimated fetal weight (EFW), into fetuses with normal growth and fetuses with late-onset fetal growth restriction (LO-FGR). Overexpression of miRNAs from neonatal cord blood belonging to LO-FGR fetuses, was validated by real-time PCR. In addition, functional characterization of overexpressed miRNAs was performed by analyzing overrepresented pathways, gene ontologies, and prioritization of synergistically working miRNAs. Three miRNAs: miR-25-3p, miR-185-5p and miR-132-3p, were significantly overexpressed in cord blood of LO-FGR fetuses. Pathway and gene ontology analysis revealed over-representation of certain molecular pathways associated with cardiac development and neuron death. In addition, prioritization of synergistically working miRNAs highlighted the importance of miR-185-5p and miR-25-3p in cholesterol efflux and starvation responses associated with LO-FGR phenotypes. Evaluation of miR-25-3p; miR-132-3p and miR-185-5p might serve as molecular biomarkers for the diagnosis and management of LO-FGR; improving the understanding of its influence on adult disease.

miRNA-23b as a biomarker of culture-positive neonatal sepsis.

BACKGROUND: Neonatal sepsis remains an important cause of morbidity and mortality. The ability to quickly and accurately diagnose neonatal sepsis based on clinical assessments and laboratory blood tests remains difficult, where haemoculture is the gold standard for detecting bacterial sepsis in blood culture. It is also very difficult to study because neonatal samples are lacking. METHODS: Forty-eight newborns suspected of sepsis admitted to the Neonatology Department of the Mother-Child Specialized Hospital of Tlemcen. From each newborn, a minimum of 1-2 ml of blood was drawn by standard sterile procedures for blood culture. The miRNA-23b level in haemoculture was evaluated by RT-qPCR. RESULTS: miR-23b levels increased in premature and full-term newborns in early onset sepsis (p < 0.001 and p < 0.005 respectively), but lowered in late onset sepsis in full-term neonates (p < 0.05) compared to the respective negative controls. miR-23b levels also increased in late sepsis in the negative versus early sepsis negative controls (p < 0.05). miR-23b levels significantly lowered in the newborns who died from both sepsis types (p < 0.0001 and p < 0.05 respectively). In early sepsis, miR-23b and death strongly and negatively correlated (correlation coefficient = - 0.96, p = 0.0019). In late sepsis, miRNA-23b and number of survivors (correlation coefficient = 0.70, p = 0.506) positively correlated. CONCLUSIONS: Lowering miR-23b levels is an important factor that favours sepsis development, which would confirm their vital protective role, and strongly suggest that they act as a good marker in molecular diagnosis and patient monitoring.

Extracellular histones disarrange vasoactive mediators release through a COX-NOS interaction in human endothelial cells.

Extracellular histones are mediators of inflammation, tissue injury and organ dysfunction. Interactions between circulating histones and vascular endothelial cells are key events in histone-mediated pathologies. Our aim was to investigate the implication of extracellular histones in the production of the major vasoactive compounds released by human endothelial cells (HUVECs), prostanoids and nitric oxide (NO). HUVEC exposed to increasing concentrations of histones (0.001 to 100 µg/ml) for 4 hrs induced prostacyclin (PGI2) production in a dose-dependent manner and decreased thromboxane A2 (TXA2) release at 100 µg/ml. Extracellular histones raised cyclooxygenase-2 (COX-2) and prostacyclin synthase (PGIS) mRNA and protein expression, decreased COX-1 mRNA levels and did not change thromboxane A2 synthase (TXAS) expression. Moreover, extracellular histones decreased both, eNOS expression and NO production in HUVEC. The impaired NO production was related to COX-2 activity and superoxide production since was reversed after celecoxib (10 µmol/l) and tempol (100 µmol/l) treatments, respectively. In conclusion, our findings suggest that extracellular histones stimulate the release of endothelial-dependent mediators through an up-regulation in COX-2-PGIS-PGI2 pathway which involves a COX-2-dependent superoxide production that decreases the activity of eNOS and the NO production. These effects may contribute to the endothelial cell dysfunction observed in histone-mediated pathologies.

Oxidative Stress and Epigenetics: miRNA Involvement in Rare Autoimmune Diseases.

Autoimmune diseases (ADs) such as Sjögren's syndrome, Kawasaki disease, and systemic sclerosis are characterized by chronic inflammation, oxidative stress, and autoantibodies, which cause joint tissue damage, vascular injury, fibrosis, and debilitation. Epigenetics participate in immune cell proliferation and differentiation, which regulates the development and function of the immune system, and ultimately interacts with other tissues. Indeed, overlapping of certain clinical features between ADs indicate that numerous immunologic-related mechanisms may directly participate in the onset and progression of these diseases. Despite the increasing number of studies that have attempted to elucidate the relationship between miRNAs and oxidative stress, autoimmune disorders and oxidative stress, and inflammation and miRNAs, an overall picture of the complex regulation of these three actors in the pathogenesis of ADs has yet to be formed. This review aims to shed light from a critical perspective on the key AD-related mechanisms by explaining the intricate regulatory ROS/miRNA/inflammation axis and the phenotypic features of these rare autoimmune diseases. The inflamma-miRs miR-155 and miR-146, and the redox-sensitive miR miR-223 have relevant roles in the inflammatory response and antioxidant system regulation of these diseases. ADs are characterized by clinical heterogeneity, which impedes early diagnosis and effective personalized treatment. Redox-sensitive miRNAs and inflamma-miRs can help improve personalized medicine in these complex and heterogeneous diseases.

Extracellular histones trigger oxidative stress-dependent induction of the NF-kB/CAM pathway via TLR4 in endothelial cells.

Extracellular histones have been reported to aggravate different pathophysiological processes by increasing vascular permeability, coagulopathy, and inflammation. In the present study, we elucidate how extracellular histones (10-100 µg/mL) concentration dependently increase cytosolic reactive oxygen species (ROS) production using human umbilical vein endothelial cells (HUVECs). Furthermore, we identify cyclooxygenase (COX) and NADPH oxidase (NOX) activity as sources of ROS production in extracellular histone-treated HUVEC. This COX/NOX-mediated ROS production is also involved in enhanced NF-kB activity and cell adhesion molecules (VCAM1 and ICAM1) expression in histone-treated HUVEC. Finally, by using different toll-like receptor (TLR) antagonists, we demonstrate the role of TLR4 in CAMs overexpression triggered by extracellular histones in endothelial cells. In conclusion, our data suggest that through TLR4 signaling, extracellular histones increase endothelial cell activation, a mechanism involving increased COX- and NOX-mediated ROS. These findings increase our understanding on how extracellular histones enhance systemic inflammatory responses in diseases in which histone release occurs as part of the pathological processes.

Identification of circulating miRNAs differentially expressed in patients with Limb-girdle, Duchenne or facioscapulohumeral muscular dystrophies.

BACKGROUND: Limb-girdle muscular dystrophy (LGMD) is a rare neuromuscular disease including a growing and heterogeneous number of subtypes with variable phenotype. Their clinical and histopathological characteristics frequently overlap with other neuromuscular dystrophies. Our goal was to identify, by a non-invasive method, a molecular signature including biochemical and epigenetic parameters with potential value for patient prognosis and stratification. RESULTS: Circulating miRNome was obtained by smallRNA-seq in plasma from LGMD patients (n = 6) and matched-controls (n = 6). Data, validated by qPCR in LGMD samples, were also examined in other common muscular dystrophies: Duchenne (DMD) (n = 5) and facioscapulohumeral muscular dystrophy (FSHD) (n = 4). Additionally, biochemical and clinical parameters were analyzed. miRNome analysis showed that thirteen differentially expressed miRs could separate LGMD vs control group by hierarchical clustering. Most of differentially expressed miRs in LGMD patients were up-regulated (miR-122-5p, miR-122b-3p, miR-6511a-3p, miR-192-5p, miR-574-3p, mir-885-3p, miR-29a-3p, miR-4646-3p, miR-203a-3p and miR-203b-5p) whilst only three of sequenced miRs were significantly down-regulated (miR-19b-3p, miR-7706, miR-323b-3p) when compared to matched controls. Bioinformatic analysis of target genes revealed cell cycle, muscle tissue development, regeneration and senescence as the most affected pathways. Four of these circulating miRs (miR-122-5p, miR-192-5p, miR-19b-3p and miR-323b-3p), together with the myomiR miR-206, were further analysed by qPCR in LGMD, DMD and FSHD. The receiver operating characteristic curves (ROC) revealed high area under the curve (AUC) values for selected miRs in all groups, indicating that these miRs have good sensitivity and specificity to distinguish LGMD, DMD and FSHD patients from healthy controls. miR-122-5p, miR-192-5p and miR-323-3p were differentially expressed compared to matched-controls in all groups but apparently, each type of muscular dystrophy showed a specific pattern of miR expression. Finally, a strong correlation between miRs and biochemical data was only found in LGMD patients: while miR-192-5p and miR-122-5p negatively correlated with CK, miR-192-5p positively correlated with vitamin D3 and ALP. CONCLUSIONS: Although limited by the small number of patients included in this study, we propose here a specific combination of circulating miR-122-5p/miR-192-5p/miR-323-3 and biochemical parameters as a potential molecular signature whose clinical value for LGMD patient prognosis and stratification should be further confirmed in a larger cohort of patients.

MicroRNA-185-5p: a marker of brain-sparing in foetuses with late-onset growth restriction.

To compare the expression of microRNA-185-5p (miR-185-5p) in normal foetuses and in foetuses with late-onset growth restriction (FGR) and to determine the factors influencing this expression. In a prospective study, 40 foetuses (22 of them with late-onset FGR and 18 with normal growth) were scanned with Doppler ultrasound after week 35 and followed until birth. Subsequently, blood samples from umbilical cords were collected after delivery to evaluate the expression of miR-185-5p using real-time qPCR. Finally, multivariable regression analysis was applied to determine the clinical and ultrasonographic factors influencing miR-185-5p expression in both normal and late-onset FGR foetuses. In comparison with normal foetuses, late-onset FGR foetuses expressed upregulation of miR-185-5p (2.26 ± 1.30 versus 1.27 ± 1.03 2^-ddCt, P = 0.011). Multivariable regression analysis confirmed that cerebroplacental ratio (P < 0.05) was the only determinant of this overexpression. FGR foetuses overexpress miR-185-5p in relation to brain-sparing. Future studies will be needed to investigate the role of miR-185 in the management of late-onset FGR.

Acute depletion of telomerase components DKC1 and NOP10 induces oxidative stress and disrupts ribosomal biogenesis via NPM1 and activation of the P53 pathway.

Mutations in DKC1, NOP10, and TINF2 genes, coding for proteins in telomerase and shelterin complexes, are responsible for diverse diseases known as telomeropathies and ribosomopathies, including dyskeratosis congenita (DC, ORPHA 1775). These genes contribute to the DC phenotype through mechanisms that are not completely understood. We previously demonstrated in models of DC that oxidative stress is an early and independent event that occurs prior to telomere shortening. To clarify the mechanisms that induce oxidative stress, we silenced genes DKC1, NOP10, and TINF2 with siRNA technology. With RNA array hybridisation, we found several altered pathways for each siRNA model. Afterwards, we identified common related genes. The silenced cell line with the most deregulated genes and pathways was siNOP10, followed by siDKC1, and then by siTINF2 to a lesser extent. The siDKC1 and siNOP10 models shared altered expression of genes in the p53 pathway, while siNOP10 and siTINF2 had the adherens junction pathway in common. We also observed that depletion of DKC1 and NOP10 H/ACA ribonucleoprotein produced ribosomal biogenesis impairment which, in turn, promoted p53 pathway activation. Finally, we found that those enzymes responsible for GSH synthesis were down-regulated in models of siDKC1 and siNOP10. In contrast, the silenced cells for TINF2 showed no disruption of ribosomal biogenesis or oxidative stress and did not produce p53 pathway activation. These results indicate that depletion of DKC1 and NOP10 promotes oxidative stress and disrupts ribosomal biogenesis which, in turn, activates the p53 pathway.

Oxidative Stress, a Crossroad Between Rare Diseases and Neurodegeneration.

: Oxidative stress is an imbalance between production and accumulation of oxygen reactive species and/or reactive nitrogen species in cells and tissues, and the capacity of detoxifying these products, using enzymatic and non-enzymatic components, such as glutathione. Oxidative stress plays roles in several pathological processes in the nervous system, such as neurotoxicity, neuroinflammation, ischemic stroke, and neurodegeneration. The concepts of oxidative stress and rare diseases were formulated in the eighties, and since then, the link between them has not stopped growing. The present review aims to expand knowledge in the pathological processes associated with oxidative stress underlying some groups of rare diseases: Friedreich's ataxia, diseases with neurodegeneration with brain iron accumulation, Charcot-Marie-Tooth as an example of rare neuromuscular disorders, inherited retinal dystrophies, progressive myoclonus epilepsies, and pediatric drug-resistant epilepsies. Despite the discrimination between cause and effect may not be easy on many occasions, all these conditions are Mendelian rare diseases that share oxidative stress as a common factor, and this may represent a potential target for therapies.

Epigenetic Regulation in the Pathogenesis of Sjögren Syndrome and Rheumatoid Arthritis.

Autoimmune rheumatic diseases, such as Sjögren syndrome (SS) and rheumatoid arthritis (RA), are characterized by chronic inflammation and autoimmunity, which cause joint tissue damage and destruction by triggering reduced mobility and debilitation in patients with these diseases. Initiation and maintenance of chronic inflammatory stages account for several mechanisms that involve immune cells as key players and the interaction of the immune cells with other tissues. Indeed, the overlapping of certain clinical and serologic manifestations between SS and RA may indicate that numerous immunologic-related mechanisms are involved in the physiopathology of both these diseases. It is widely accepted that epigenetic pathways play an essential role in the development and function of the immune system. Although many published studies have attempted to elucidate the relation between epigenetic modifications (e.g. DNA methylation, histone post-translational modifications, miRNAs) and autoimmune disorders, the contribution of epigenetic regulation to the pathogenesis of SS and RA is at present poorly understood. This review attempts to shed light from a critical point of view on the identification of the most relevant epigenetic mechanisms related to RA and SS by explaining intricate regulatory processes and phenotypic features of both autoimmune diseases. Moreover, we point out some epigenetic markers which can be used to monitor the inflammation status and the dysregulated immunity in SS and RA. Finally, we discuss the inconvenience of using epigenetic data obtained from bulk immune cell populations instead specific immune cell subpopulations.

Extracellular histones activate autophagy and apoptosis via mTOR signaling in human endothelial cells.

Circulating histones have been proposed as targets for therapy in sepsis and hyperinflammatory symptoms. However, the proposed strategies have failed in clinical trials. Although different mechanisms for histone-related cytotoxicity are being explored, those mediated by circulating histones are not fully understood. Extracellular histones induce endothelial cell death, thereby contributing to the pathogenesis of complex diseases such as sepsis and septic shock. Therefore, the comprehension of cellular responses triggered by histones is capital to design effective therapeutic strategies. Here we report how extracellular histones induce autophagy and apoptosis in a dose-dependent manner in cultured human endothelial cells. In addition, we describe how histones regulate these pathways via Sestrin2/AMPK/ULK1-mTOR and AKT/mTOR. Furthermore, we evaluate the effect of Toll-like receptors in mediating autophagy and apoptosis demonstrating how TLR inhibitors do not prevent apoptosis and/or autophagy induced by histones. Our results confirm that histones and autophagic pathways can be considered as novel targets to design therapeutic strategies in endothelial damage.

Small RNA-seq analysis of circulating miRNAs to identify phenotypic variability in Friedreich's ataxia patients.

Friedreich's ataxia (FRDA; OMIM 229300), an autosomal recessive neurodegenerative mitochondrial disease, is the most prevalent hereditary ataxia. In addition, FRDA patients have shown additional non-neurological features such as scoliosis, diabetes, and cardiac complications. Hypertrophic cardiomyopathy, which is found in two thirds of patients at the time of diagnosis, is the primary cause of death in these patients. Here, we used small RNA-seq of microRNAs (miRNAs) purified from plasma samples of FRDA patients and controls. Furthermore, we present the rationale, experimental methodology, and analytical procedures for dataset analysis. This dataset will facilitate the identification of miRNA signatures and provide new molecular explanation for pathological mechanisms occurring during the natural history of FRDA. Since miRNA levels change with disease progression and pharmacological interventions, miRNAs will contribute to the design of new therapeutic strategies and will improve clinical decisions.

Acute telomerase components depletion triggers oxidative stress as an early event previous to telomeric shortening.

Loss of function of dyskerin (DKC1), NOP10 and TIN2 are responsible for different inheritance patterns of Dyskeratosis congenita (DC; ORPHA1775). They are key components of telomerase (DKC1 and NOP10) and shelterin (TIN2), and play an important role in telomere homeostasis. They participate in several fundamental cellular processes by contributing to Dyskeratosis congenita through mechanisms that are not fully understood. Presence of oxidative stress was postulated to result from telomerase ablation. However, the resulting disturbed redox status can promote telomere attrition by generating a vicious circle, which promotes cellular senescence. This fact prompted us to study if acute loss of DKC1, NOP10 and TINF2 can promote redox disequilibrium as an early event when telomere shortening has not yet taken place. We generated siRNA-mediated (DKC1, NOP10 and TINF2) cell lines by RNA interference, which was confirmed by mRNA and protein expression analyses. No telomere shortening occurred in any silenced cell line. Depletion of H/ACA ribonucleoproteins DKC1 and NOP10 diminished telomerase activity via TERC down-regulation, and produced alterations in pseudouridylation and ribosomal biogenesis. An increase in the GSSG/GSH ratio, carbonylated proteins and oxidized peroxiredoxin-6 was observed, in addition to MnSOD and TRX1 overexpression in the siRNA DC cells. Likewise, high PARylation levels and high PARP1 protein expression were detected. In contrast, the silenced TINF2 cells did not alter any evaluated oxidative stress marker. Altogether these findings lead us to conclude that loss of DKC1 and NOP10 functions induces oxidative stress in a telomere shortening independent manner.

Circulating miRNAs as diagnostic biomarkers for adolescent idiopathic scoliosis.

The aetiology of adolescent idiopathic scoliosis (AIS) has been linked to many factors, such as asymmetric growth, neuromuscular condition, bone strength and genetic background. Recently, epigenetic factors have been proposed as contributors of AIS physiopathology, but information about the molecular mechanisms and pathways involved is scarce. Regarding epigenetic factors, microRNAs (miRNAs) are molecules that contribute to gene expression modulation by regulating important cellular pathways. We herein used Next-Generation Sequencing to discover a series of circulating miRNAs detected in the blood samples of AIS patients, which yielded a unique miRNA biomarker signature that diagnoses AIS with high sensitivity and specificity. We propose that these miRNAs participate in the epigenetic control of signalling pathways by regulating osteoblast and osteoclast differentiation, thus modulating the genetic background of AIS patients. Our study yielded two relevant results: 1) evidence for the deregulated miRNAs that participate in osteoblast/osteoclast differentiation mechanisms in AIS; 2) this miRNA-signature can be potentially used as a clinical tool for molecular AIS diagnosis. Using miRNAs as biomarkers for AIS diagnostics is especially relevant since miRNAs can serve for early diagnoses and for evaluating the positive effects of applied therapies to therefore reduce the need of high-risk surgical interventions.

Role of p16INK4a and BMI-1 in oxidative stress-induced premature senescence in human dental pulp stem cells.

Human dental pulp stem cells (hDPSCs) are a source for cell therapy. Before implantation, an in vitro expansion step is necessary, with the inconvenience that hDPSCs undergo senescence following a certain number of passages, loosing their stemness properties. Long-term in vitro culture of hDPSCs at 21% (ambient oxygen tension) compared with 3-6% oxygen tension (physiological oxygen tension) caused an oxidative stress-related premature senescence, as evidenced by increased ß-galactosidase activity and increased lysil oxidase expression, which is mediated by p16INK4a pathway. Furthermore, hDPSCs cultured at 21% oxygen tension underwent a downregulation of OCT4, SOX2, KLF4 and c-MYC factors, which was recued by BMI-1 silencing. Thus, p16INK4a and BMI-1 might play a role in the oxidative stress-associated premature senescence. We show that it is important for clinical applications to culture cells at physiological pO2 to retain their stemness characteristics and to delay senescence.

Cellular Responses in Human Dental Pulp Stem Cells Treated with Three Endodontic Materials.

Human dental pulp stem cells (HDPSCs) are of special relevance in future regenerative dental therapies. Characterizing cytotoxicity and genotoxicity produced by endodontic materials is required to evaluate the potential for regeneration of injured tissues in future strategies combining regenerative and root canal therapies. This study explores the cytotoxicity and genotoxicity mediated by oxidative stress of three endodontic materials that are widely used on HDPSCs: a mineral trioxide aggregate (MTA-Angelus white), an epoxy resin sealant (AH-Plus cement), and an MTA-based cement sealer (MTA-Fillapex). Cell viability and cell death rate were assessed by flow cytometry. Oxidative stress was measured by OxyBlot. Levels of antioxidant enzymes were evaluated by Western blot. Genotoxicity was studied by quantifying the expression levels of DNA damage sensors such as ATM and RAD53 genes and DNA damage repair sensors such as RAD51 and PARP-1. Results indicate that AH-Plus increased apoptosis, oxidative stress, and genotoxicity markers in HDPSCs. MTA-Fillapex was the most cytotoxic oxidative stress inductor and genotoxic material for HDPSCs at longer times in preincubated cell culture medium, and MTA-Angelus was less cytotoxic and genotoxic than AH-Plus and MTA-Fillapex at all times assayed.

Increased oxidative stress and impaired antioxidant response in Lafora disease.

Lafora disease (LD, OMIM 254780, ORPHA501) is a fatal neurodegenerative disorder characterized by the presence of glycogen-like intracellular inclusions called Lafora bodies and caused, in the vast majority of cases, by mutations in either EPM2A or EPM2B genes, encoding respectively laforin and malin. In the last years, several reports have revealed molecular details of these two proteins and have identified several processes affected in LD, but the pathophysiology of the disease still remains largely unknown. Since autophagy impairment has been reported as a characteristic treat in both Lafora disease cell and animal models, and as there is a link between autophagy and mitochondrial performance, we sought to determine if mitochondrial function could be altered in those models. Using fibroblasts from LD patients, deficient in laforin or malin, we found mitochondrial alterations, oxidative stress and a deficiency in antioxidant enzymes involved in the detoxification of reactive oxygen species (ROS). Similar results were obtained in brain tissue samples from transgenic mice deficient in either the EPM2A or EPM2B genes. Furthermore, in a proteomic analysis of brain tissue obtained from Epm2b-/- mice, we observed an increase in a modified form of peroxiredoxin-6, an antioxidant enzyme involved in other neurological pathologies, thus corroborating an alteration of the redox condition. These data support that oxidative stress produced by an increase in ROS production and an impairment of the antioxidant enzyme response to this stress play an important role in development of LD.

Glutathione and cellular redox control in epigenetic regulation.

Epigenetics is defined as the mitotically/meiotically heritable changes in gene expression that are not due to changes in the primary DNA sequence. Over recent years, growing evidence has suggested a link between redox metabolism and the control of epigenetic mechanisms. The effect of the redox control, oxidative stress, and glutathione (GSH) on the epigenetic mechanisms occur at different levels affecting DNA methylation, miRNAs expression, and histone post-translational modifications (PTMs). Furthermore, a number of redox PTMs are being described, so enriching the histone code. Pioneer works showed how oxidized GSH inhibits the activity of S-adenosyl methionine synthetase, MAT1A, a key enzyme involved in the synthesis of S-adenosyl methionine (SAM), which is used by DNA methyltransferases (DNMTs) and histone methyltransferases (HMTs). Alteration in NAD /NADH ratio affects the activity of class III histone deacetylases (HDACs) and poly-ADP ribosyltransferases (PARPs). Furthermore, the iron redox state of the catalytic center of key enzymes influences the activity of HDACs and the activity of Tet methylcytosine dioxygenases (DNA demetylases) and JmjC histone demethylases. In this communication, we will show the intricate mechanisms that participate in the redox control of the epigenetic mechanisms. We specially focus our work in the characterization of new PTMs in histones, such as histone carbonylation and glutathionylation. Demonstrating how GSH influences the epigenetic mechanisms beyond a mere regulation of SAM levels. The mechanisms described in this communication place GSH and redox control in the landscape of the epigenetic regulation. The results shown underscore the relevant role that oxidative stress and GSH play as key factors in epigenetics, opening a new window for understating the underlying mechanisms that control cell differentiation, proliferation, development, and disease.

Characterization of the antioxidant systems in different complementation groups of Dyskeratosis Congenita.

The telomerase complex and Telosome regulate, maintenance and repair telomeres. The telomerase complex is formed by complex of protein (TERT, Dyskerin, GAR, NHP2, NOP10) and nucleic acid (TERC) that together work as a reverse transcriptase. The Telosoma comprises a network of protein (TRF2, TRF1, TIN2, RAP1, TPP1 and POT1). Furthermore, dyskeratosis congenita (DC) (ORPHA1775) is a rare disease with similar characteristics to premature aging. DC is a genetically heterogeneous disease caused by mutations in the genes that encoding for different subunits of the telomerase complex and Telosome. It is known that the telomeric DNA is susceptible to oxidative stress, and telomerase activity dependent cellular redox environment. Recently a correlation between telomerase activity and catalase activity was established, and it has suggested a role of antioxidant extranuclear telomerase. However, it is not yet clear whether there is any relationship or connection between molecular telomerase activity and cellular antioxidant defense. In this paper, by using the technology of RNA interference (siRNA) silencing DKC1, NOP10 genes of telomerase complex and TINF2 of Telosoma in HeLa cells, on cellular antioxidant capacity will be presented. It was intended to see if there is a cellular effect related to the production of oxidative stress or alteration of antioxidant systems after silencing these components involved in telomere maintenance. In this paper we have evaluated the levels of DKC1, NOP10, TINF2 levels of antioxidant enzymes (CuZnSOD, MnSOD, Catalase, Gpx1, Grx1 and Trx1) by RT- qPCR and Western blotting. We analyzed the production of reactive oxygen species by fluorimetry and also assessed the activity of the telomerase complex by Sybr Green RT- QTrap.