RESUMEN
Introduction. Adherence is a major virulence trait in Candida glabrata that, in many strains, depends on the EPA (epithelial adhesin) genes, which confer the ability to adhere to epithelial and endothelial cells of the host. The EPA genes are generally found at subtelomeric regions, which makes them subject to subtelomeric silencing. In C. glabrata, subtelomeric silencing depends on different protein complexes, such as silent information regulator and yKu complexes, and other proteins, such as Repressor/activator protein 1 (Rap1) and Abf1. At the EPA1 locus, which encodes the main adhesin Epa1, we previously found at least two cis-acting elements, the protosilencer Sil2126 and the negative element, that contribute to the propagation of silencing from the telomere to the subtelomeric region.Hypothesis. Abf1 binds to the regulatory regions of EPA1 and other regions at the telomere E-R, thereby negatively regulating EPA1 transcription.Aim. To determine whether Abf1 and Rap1 silencing proteins bind to previously identified cis-acting elements on the right telomere of chromosome E (E-R subtelomeric region), resulting in negative regulation of EPA1 transcription and infer Abf1 and Rap1 recognition sites in C. glabrata.Methodology. We used chromatin immunoprecipitation (ChIP) followed by quantitative PCR to determine the binding sites for Abf1 and Rap1 in the intergenic regions between EPA1 and EPA2 and HYR1 and EPA1, and mutants were used to determine the silencing level of the EPA1 promoter region.Results. We found that Abf1 predominantly binds to the EPA1 promoter region, leading to negative regulation of EPA1 expression. Furthermore, the mutant abf1-43, which lacks the last 43 amino acids at its C-terminal end and is defective for subtelomeric silencing, exhibits hyperadherence to epithelial cells in vitro compared to the parental strain, suggesting that EPA1 is derepressed. We also determined the motif-binding sequences for Abf1 and Rap1 in C. glabrata using data from the ChIP assays.Conclusion. Together these data indicate that Abf1 negatively regulates EPA1 expression, leading to decreased adhesion of C. glabrata to epithelial cells.
Asunto(s)
Candida glabrata , Proteínas Fúngicas , Regulación Fúngica de la Expresión Génica , Candida glabrata/genética , Candida glabrata/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Adhesión Celular , Telómero/metabolismo , Telómero/genética , Humanos , Proteínas de Unión a Telómeros/genética , Proteínas de Unión a Telómeros/metabolismo , Regiones Promotoras Genéticas , LectinasRESUMEN
This study focuses on the biological impacts of deleting the telomerase RNA from Leishmania major (LeishTER), a parasite responsible for causing leishmaniases, for which no effective treatment or prevention is available. TER is a critical player in the telomerase ribonucleoprotein complex, containing the template sequence copied by the reverse transcriptase component during telomere elongation. The success of knocking out both LeishTER alleles was confirmed, and no off-targets were detected. LmTER-/- cells share similar characteristics with other TER-depleted eukaryotes, such as altered growth patterns and partial G0/G1 cell cycle arrest in early passages, telomere shortening, and elevated TERRA expression. They also exhibit increased γH2A phosphorylation, suggesting that the loss of LeishTER induces DNA damage signaling. Moreover, pro-survival autophagic signals and mitochondrion alterations were shown without any detectable plasma membrane modifications. LmTER-/- retained the ability to transform into metacyclics, but their infectivity capacity was compromised. Furthermore, the overexpression of LeishTER was also deleterious, inducing a dominant negative effect that led to telomere shortening and growth impairments. These findings highlight TER's vital role in parasite homeostasis, opening discussions about its potential as a drug target candidate against Leishmania.
Asunto(s)
Proliferación Celular , Leishmania major , ARN , Telomerasa , Leishmania major/genética , Leishmania major/patogenicidad , Telomerasa/genética , Telomerasa/metabolismo , ARN/genética , ARN/metabolismo , Animales , Técnicas de Inactivación de Genes , Telómero/metabolismo , Telómero/genéticaRESUMEN
MiRNAs, a class of non-coding RNA molecules, have emerged as critical modulators of telomere length and telomerase activity by finely tuning the expression of target genes (and not gene targets) within signaling pathways involved in telomere homeostasis. The primary objective of this systematic review was to compile and synthesize the existing body of knowledge on the role, association, and involvement of miRNAs in telomere length. Additionally, the review explored the regulation, function, and activation mechanism of the human telomerase reverse transcriptase (hTERT) gene and telomerase activity in tumor cells. A comprehensive analysis of 47 selected articles revealed 40 distinct miRNAs involved in these processes. These miRNAs were shown to exert their function, in both clinical cases and cell line models, either directly or indirectly, regulating hTERT and telomerase activity through distinct molecular mechanisms. The regulatory roles of these miRNAs significantly affected major cancer phenotypes, with outcomes largely dependent on the tissue type and the cellular actions within the tumor cells, whereby they functioned as oncogenes or tumor suppressors. These findings strongly support the pivotal role of miRNAs in modulating telomere length and telomerase activity, thereby contributing to the intricate and complex regulation of telomere homeostasis in tumor cells. Moreover, they emphasize the potential of targeting miRNAs and key regulatory genes as therapeutic strategies to disrupt cancer cell growth and promote senescence, offering promising avenues for novel cancer treatments.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , MicroARNs , Neoplasias , Telomerasa , Homeostasis del Telómero , Telómero , Humanos , Telomerasa/genética , Telomerasa/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Homeostasis del Telómero/genética , Neoplasias/genética , Neoplasias/patología , Neoplasias/metabolismo , Telómero/metabolismo , Telómero/genética , AnimalesRESUMEN
BACKGROUND: Telomeropathies are a group of inherited disorders caused by germline pathogenic variants in genes involved in telomere maintenance, resulting in excessive telomere attrition that affects several tissues, including hematopoiesis. RecQ and RTEL1 helicases contribute to telomere maintenance by unwinding telomeric structures such as G-quadruplexes (G4), preventing replication defects. Germline RTEL1 variants also are etiologic in telomeropathies. METHODS AND RESULTS: Here we investigated the expression of RecQ (RECQL1, BLM, WRN, RECQL4, and RECQL5) and RTEL1 helicase genes in peripheral blood mononuclear cells (PBMCs) from human telomeropathy patients. The mRNA expression levels of all RecQ helicases, but not RTEL1, were significantly downregulated in patients' primary cells. Reduced RecQ expression was not attributable to cell proliferative exhaustion, as RecQ helicases were not attenuated in T cells exhausted in vitro. An additional fifteen genes involved in DNA damage repair and RecQ functional partners also were downregulated in the telomeropathy cells. CONCLUSION: These findings indicate that the expression of RecQ helicases and functional partners involved in DNA repair is downregulated in PBMCs of telomeropathy patients.
Asunto(s)
Leucocitos Mononucleares , RecQ Helicasas , Adulto , Femenino , Humanos , Masculino , ADN Helicasas/genética , ADN Helicasas/metabolismo , Reparación del ADN/genética , Leucocitos Mononucleares/metabolismo , RecQ Helicasas/genética , RecQ Helicasas/metabolismo , Telómero/metabolismo , Telómero/genética , Homeostasis del Telómero/genéticaRESUMEN
Polycystic ovary syndrome (PCOS) is a multifactorial disorder and obesity occurs in 38% to 88% of these women. Although hyperandrogenism may contribute to telomere lengthening, increased body mass index (BMI) is associated with telomere erosion. We sought to compare leukocyte telomere length (LTL) in PCOS women with normal, overweight, and obese BMI. We evaluated the relationship between LTL and clinical variables of PCOS and inflammatory biomarkers independent of BMI. A total of 348 women (243 PCOS and 105 non-PCOS) were evaluated for anthropometric measures, total testosterone, androstenedione, estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG), free androgen index (FAI), fasting insulin and glycemia, lipid profile, homocysteine, C-reactive protein (CRP) and homeostatic model of insulin resistance (HOMA-IR). LTL was measured by qPCR. The PCOS group presented higher weight, waist circumference, BMI, testosterone, LH, fasting insulin, FAI, and HOMA-IR, and lower E2, SHBG, and fasting glycemia measures compared with the non-PCOS. When stratified by BMI, LTL was increased in all subgroups in PCOS compared to non-PCOS. However, in the PCOS group, LTL was lower in overweight (P = 0.0187) and obese (P = 0.0018) compared to normal-weight women. The generalized linear model showed that BMI, androstenedione, homocysteine, and CRP were associated with telomere biology. Women with PCOS had longer LTL, however, overweight or obesity progressively contributes to telomere shortening and may affect reproductive outcomes of PCOS, while androstenedione may increase LTL.
Asunto(s)
Índice de Masa Corporal , Obesidad , Síndrome del Ovario Poliquístico , Acortamiento del Telómero , Humanos , Síndrome del Ovario Poliquístico/genética , Síndrome del Ovario Poliquístico/sangre , Síndrome del Ovario Poliquístico/metabolismo , Femenino , Obesidad/genética , Obesidad/sangre , Adulto , Adulto Joven , Resistencia a la Insulina , Telómero/metabolismo , Leucocitos/metabolismo , Biomarcadores/sangreRESUMEN
Subtelomeric gene silencing is the negative transcriptional regulation of genes located close to telomeres. This phenomenon occurs in a variety of eukaryotes with salient physiological implications, such as cell adherence, virulence, immune-system escape, and ageing. The process has been widely studied in the budding yeast Saccharomyces cerevisiae, where genes involved in this process have been identified mostly on a gene-by-gene basis. Here, we introduce a quantitative approach to study gene silencing, that couples the classical URA3 reporter with GFP monitoring, amenable to high-throughput flow cytometry analysis. This dual silencing reporter was integrated into several subtelomeric loci in the genome, where it showed a gradual range of silencing effects. By crossing strains with this dual reporter at the COS12 and YFR057W subtelomeric query loci with gene-deletion mutants, we carried out a large-scale forward screen for potential silencing factors. The approach was replicable and allowed accurate detection of expression changes. Results of our comprehensive screen suggest that the main players influencing subtelomeric silencing were previously known, but additional potential factors underlying chromatin conformation are involved. We validate and report the novel silencing factor LGE1, a protein with unknown molecular function required for histone H2B ubiquitination. Our strategy can be readily combined with other reporters and gene perturbation collections, making it a versatile tool to study gene silencing at a genome-wide scale.
Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomycetales , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas Reguladoras de Información Silente de Saccharomyces cerevisiae/genética , Proteínas Reguladoras de Información Silente de Saccharomyces cerevisiae/metabolismo , Saccharomycetales/genética , Saccharomycetales/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Telómero/genética , Telómero/metabolismo , Heterocromatina/metabolismo , Regulación Fúngica de la Expresión GénicaRESUMEN
OBJECTIVE: To determine the effect of the consumption of Sechium edule (1.5â g/day) for six months on oxidative stress (OxS) and inflammation markers and its association with telomere length (TL) in older adults with metabolic syndrome (MetS). METHODS: The study was conducted in a sample of 48 older adults: placebo (EP) and experimental (EG) groups. Lipoperoxides, protein carbonylation, 8-OHdG, total oxidant status (TOS), SOD, GPx, H2O2 inhibition, total antioxidant status (TAS), inflammatory cytokines (IL6, IL10, TNF-α), and TL were measured before and six months post-treatment. RESULTS: We found a significant decrease in the levels of lipoperoxides, protein carbonylation, 8-OHdG, TOS in the EG in comparison PG. Likewise, a significante increase of TAS, IL-6, and IL-10 levels was found at six months post-treatment in EG in comparison with PG. TL showed a statistically significant decrease in PG compared to post-treatment EG. CONCLUSIONS: Our findigns showed that the supplementation of Sechium edule has antioxidant, and anti-inflammatory effects, and diminushion of shortening of telomeric DNA in older adults with MetS. This would be the first study that shows that the intervention with Sechium edule has a possible geroprotective effect by preventing telomeres from shortening as usually happens in these patients. Therefore, suggesting a protection of telomeric DNA and genomic DNA.
Asunto(s)
Antioxidantes , Síndrome Metabólico , Humanos , Anciano , Antioxidantes/uso terapéutico , Antioxidantes/metabolismo , Síndrome Metabólico/tratamiento farmacológico , Peróxidos Lipídicos , Peróxido de Hidrógeno , Telómero/metabolismoRESUMEN
BACKGROUND: The motivations for and effects of ethanol consumption vary considerably among individuals, and as such, a significant proportion of the population is prone to substance abuse and its negative consequences in the physical, social, and psychological spheres. In a biological context, the characterization of these phenotypes provides clues for understanding the neurological complexity associated with ethanol abuse behavior. Therefore, the objective of this research was to characterize four ethanol preference phenotypes described in zebrafish: Light, Heavy, Inflexible, and Negative Reinforcement. METHODS: To do this, we evaluated the telomere length, mtDNA copy number using real-time quantitative PCR (qPCR), and the activity of these antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the brain, and the interactions between these biomarkers. Changes observed in these parameters were associated with ethanol consumption and alcohol abuse. RESULTS: The Heavy, Inflexible, and Negative Reinforcement phenotypes showed ethanol preference. This was particularly the case with the Inflexible phenotype, which was the group with the greatest ethanol preference. These three phenotypes showed telomere shortening as well as high SOD/CAT and/or GPx activities, while the Heavy phenotype also showed an increase in the mtDNA copy number. However, the Light phenotype, containing individuals without ethanol preference, did not demonstrate any changes in the analyzed parameters even after being exposed to the drug. Additionally, the PCA analysis showed a tendency to cluster the Light and Control groups differently from the other ethanol preference phenotypes. There was also a negative correlation between the results of the relative telomere length and SOD and CAT activity, providing further evidence of the biological relationship between these parameters. CONCLUSIONS: Our results showed differential molecular and biochemistry patterns in individuals with ethanol preference, suggesting that the molecular and biochemical basis of alcohol abuse behavior extends beyond its harmful physiological effects, but rather is correlated with preference phenotypes.
Asunto(s)
Alcoholismo , Antioxidantes , Animales , Antioxidantes/farmacología , Pez Cebra/genética , Pez Cebra/metabolismo , Variaciones en el Número de Copia de ADN , Catalasa/genética , Catalasa/metabolismo , Catalasa/farmacología , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Etanol , Encéfalo/metabolismo , Mitocondrias/metabolismo , ADN Mitocondrial/genética , Telómero/genética , Telómero/metabolismo , Estrés OxidativoRESUMEN
Telomeres and telomerase are closely linked to uncontrolled cellular proliferation, immortalization and carcinogenesis. Telomerase has been largely studied in the context of cancer, including leukemias. Deregulation of human telomerase gene hTERT is a well-established step in leukemia development. B-acute lymphoblastic leukemia (B-ALL) recovery rates exceed 90% in children; however, the relapse rate is around 20% among treated patients, and 10% of these are still incurable. This review highlights the biological and clinical relevance of telomerase for B-ALL and the implications of its canonical and non-canonical action on signaling pathways in the context of disease and treatment. The physiological role of telomerase in lymphocytes makes the study of its biomarker potential a great challenge. Nevertheless, many works have demonstrated that high telomerase activity or hTERT expression, as well as short telomeres, correlate with poor prognosis in B-ALL. Telomerase and related proteins have been proven to be promising pharmacological targets. Likewise, combined therapy with telomerase inhibitors may turn out to be an alternative strategy for B-ALL.
Asunto(s)
Leucemia-Linfoma Linfoblástico de Células Precursoras B , Leucemia-Linfoma Linfoblástico de Células Precursoras , Telomerasa , Niño , Humanos , Telomerasa/genética , Telomerasa/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Acortamiento del Telómero , Telómero/genética , Telómero/metabolismoRESUMEN
PIN1 is the only known enzyme capable of recognizing and isomerizing the phosphorylated Serine/ThreonineProline motif. Through this mechanism, PIN1 controls diverse cellular functions, including telomere maintenance. Both PIN1 overexpression and its involvement in oncogenic pathways are involved in several cancer types, including glioblastoma (GBM), a lethal disease with poor therapeutic resources. However, knowledge of the role of PIN1 in GBM is limited. Thus, the present work aimed to study the role of PIN1 as a telomere/telomerase regulator and its contribution to tumor biology. PIN1 knockout (KO) LN229 cell variant using CRISPR/Cas9 was developed and compared with PIN1 LN229 expressing cells. To study the effect of PIN1 absence, status of NFκB pathway was evaluated by luciferase reporter gene assay and quantitative PCR. Results revealed that PIN1 deletion in GBM cells diminished the active levels of NFκB and decrease the transcription of il8 and htert genes. Then, telomere/telomerase related processes were studied by RQTRAP assay and telomere length determination by qPCR, obtaining a reduction both in telomerase activity as in telomere length in PIN1 KO cells. In addition, measurement of SA ßgalactosidase and caspase3 activities revealed that loss of PIN1 triggers senescence and apoptosis. Finally, migration, cell cycle progression and tumorigenicity were studied by flow cytometry/western blot, Transwell assay and in vivo experiments, respectively. PIN1 deletion decreased migration as well as cell cycle progression by increasing doubling time and also resulted in the loss of LN229 cell ability to form tumors in mice. These results highlight the role of PIN1 in telomere homeostasis and GBM progression, which supports PIN1 as a potential molecular target for the development of novel therapeutic agents for GBM treatment.
Asunto(s)
Glioblastoma , Telomerasa , Humanos , Animales , Ratones , Glioblastoma/patología , FN-kappa B/genética , FN-kappa B/metabolismo , Telomerasa/metabolismo , Reacción en Cadena de la Polimerasa , Telómero/genética , Telómero/metabolismo , Línea Celular Tumoral , Peptidilprolil Isomerasa de Interacción con NIMA/genética , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismoRESUMEN
Pathogenic germline variants in the protection of telomeres 1 gene (POT1) have been associated with predisposition to a range of tumour types, including melanoma, glioma, leukaemia and cardiac angiosarcoma. We sequenced all coding exons of the POT1 gene in 2928 European-descent melanoma cases and 3298 controls, identifying 43 protein-changing genetic variants. We performed POT1-telomere binding assays for all missense and stop-gained variants, finding nine variants that impair or disrupt protein-telomere complex formation, and we further define the role of variants in the regulation of telomere length and complex formation through molecular dynamics simulations. We determine that POT1 coding variants are a minor contributor to melanoma burden in the general population, with only about 0.5% of melanoma cases carrying germline pathogenic variants in this gene, but should be screened in individuals with a strong family history of melanoma and/or multiple malignancies.
Asunto(s)
Melanoma , Neoplasias Cutáneas , Humanos , Melanoma/genética , Neoplasias Cutáneas/genética , Complejo Shelterina , Proteínas de Unión a Telómeros/genética , Telómero/metabolismo , Estudios de Casos y Controles , Melanoma Cutáneo MalignoRESUMEN
BACKGROUND: The pathogenesis of psoriasis vulgaris involves changes in DNA molecules, genomic instability, telomere attrition, and epigenetic alterations among them. These changes are also considered important mechanisms of aging in cells and tissues. OBJECTIVE: This study dealt with oxidation damage, telomere length and methylation status in DNA originating from peripheral blood of 41 psoriatic patients and 30 healthy controls. METHODS: Oxidative damage of serum DNA/RNA was determined immunochemically. Real-time PCR was used for the analysis of the telomere length. ELISA technique determined levels of 5-methylcytosine in blood cells' DNA. RESULTS: Oxidative damage of serum DNA/RNA was higher in patients than in controls (median, 3758 vs. 2286pg/mL, p<0.001). A higher length of telomeres per chromosome was found in patients whole-cell DNA than in controls (3.57 vs. 3.04 kilobases, p=0.011). A negative correlation of the length of telomeres with an age of the control subjects was revealed (Spearman's rho=-0.420, p=0.028). Insignificantly different levels of 5-methylcytosine in patients and controls were observed (33.20 vs. 23.35%, p=0.234). No influences of sex, smoking, BMI, PASI score, and metabolic syndrome on the methylation status were found. STUDY LIMITATIONS: i) A relatively small number of the participants, particularly for reliable subgroup analyses, ii) the Caucasian origin of the participants possibly influencing the results of the parameters determined, and iii) Telomerase activity was not directly measured in serum or blood cells. CONCLUSION: The study demonstrated increased levels of oxidized DNA/RNA molecules in the serum of patients with exacerbated psoriasis vulgaris. The results were minimally influenced by sex, the presence of metabolic syndrome, or cigarette smoking. In the psoriatic blood cells' DNA, the authors observed longer telomeres compared to healthy controls, particularly in females. Insignificantly higher global DNA methylation in psoriasis cases compared to the controls indicated marginal clinical importance of this epigenetic test performed in the blood cells' DNA.
Asunto(s)
Síndrome Metabólico , Psoriasis , Femenino , Humanos , 5-Metilcitosina , Epigénesis Genética , Estrés Oxidativo/genética , ARN/metabolismo , Telómero/genética , Telómero/metabolismo , ADN/metabolismo , Psoriasis/genéticaRESUMEN
BACKGROUND: Since the 1980s, cancer research has focused primarily on developing new therapeutic agents targeting DNA alterations rather than understanding cancer as an integrated system composed of several modules. In this sense, G-quadruplex (G4) nucleic acids are a promising target for drug development for cancer therapy since they exist in the chromosomal telomeric sequences and the promoter regions of numerous genes. The G4 structures within telomeric DNA can inhibit telomerase activity and prevent the proliferation and immortalization of cancer cells. Furthermore, such G4 systems within the promoter regions of oncogenes can inhibit the transcription and expression of the oncogene. OBJECTIVE: The rational design of small molecules such as organic ligands and their metal- organic derivative compounds can stabilize G4 structures through different binding modes on several G4 DNA topologies. Metal-based compounds have demonstrated their competitiveness compared to organic molecules to distinguish G4 over the DNA duplex owing to their convenient coordination features, positive charge, and electron density promoted by organic ligand. RESULTS: This article is a comprehensive review of metal compounds G4-binders and their structural features that confer them the ability to recognize G-quartets and stabilize several DNA G4s. CONCLUSION: This stabilization can be achieved through extended square aromatic surfaces, increased hydrophobicity, different auxiliary ligands, axially coordinated ligands, and the nature of the metal center.
Asunto(s)
Antineoplásicos , G-Cuádruplex , Neoplasias , Humanos , Ligandos , Antineoplásicos/farmacología , Antineoplásicos/metabolismo , ADN/química , Neoplasias/tratamiento farmacológico , Compuestos Orgánicos , Metales , Telómero/metabolismoRESUMEN
Exonic sequencing identified a family with idiopathic pulmonary fibrosis (IPF) containing a previously unreported heterozygous mutation in POT1 p.(L259S). The family displays short telomeres and genetic anticipation. We found that POT1(L259S) is defective in binding the telomeric overhang, nuclear accumulation, negative regulation of telomerase, and lagging strand maintenance. Patient cells containing the mutation display telomere loss, lagging strand defects, telomere-induced DNA damage, and premature senescence with G1 arrest. Our data suggest POT1(L259S) is a pathogenic driver of IPF and provide insights into gene therapy options.
Asunto(s)
Fibrosis Pulmonar Idiopática , Telomerasa , Humanos , Fibrosis Pulmonar Idiopática/genética , Complejo Shelterina , Telomerasa/genética , Telomerasa/metabolismo , Telómero/genética , Telómero/metabolismo , Proteínas de Unión a Telómeros/genéticaRESUMEN
The long noncoding RNA (lncRNA) telomeric repeat-containing RNA (TERRA) has been associated with telomeric homeostasis, telomerase recruitment, and the process of chromosome healing; nevertheless, the impact of this association has not been investigated during the carcinogenic process. Determining whether changes in TERRA expression are a cause or a consequence of cell transformation is a complex task because studies are usually carried out using either cancerous cells or tumor samples. To determine the role of this lncRNA in cellular aging and chromosome healing, we evaluated telomeric integrity and TERRA expression during the establishment of a clone of untransformed myeloid cells. We found that reduced expression of TERRA disturbed the telomeric homeostasis of certain loci, but the expression of the lncRNA was affected only when the methylation of subtelomeric bivalent chromatin domains was compromised. We conclude that the disruption in TERRA homeostasis is a consequence of cellular transformation and that changes in its expression profile can lead to telomeric and genomic instability.
Asunto(s)
ARN Largo no Codificante , Homeostasis del Telómero , Cromatina/genética , Heterocromatina , Metilación , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Telómero/genética , Telómero/metabolismoRESUMEN
The Mexican axolotl is one of the few vertebrates that is able to replace its lost body parts during lifespan. Due to its remarkable regenerative abilities, the axolotl emerged as a model organism especially for limb regeneration. Telomeres and the telomerase enzyme are crucial for regeneration and protection against aging processes and degenerating diseases. Despite its relevance for regeneration, the axolotl telomerase and telomere length have not yet been investigated. Therefore, in the present paper, we reveal the sequence of the axolotl telomerase reverse transcriptase gene (Tert) and protein (TERT). Multiple sequence alignment (MSA) showed the known conserved RT- and TERT-specific motifs and residues found in other TERTs. In addition, we establish methods to determine the Tert expression (RT-PCR) and telomerase activity (Q-TRAP) of adult axolotl and blastema tissues. We found that both differentiated forelimb tissue and regenerating blastema tissue express Tert and show telomerase activity. Furthermore, blastema tissue appears to exhibit a higher Tert expression and telomerase activity. The presence of active telomerase in adult somatic cells is a decisive difference to somatic cells of non-regenerating vertebrates, such as humans. These findings indicate that telomere biology may play a key role in the regenerative abilities of cells.
Asunto(s)
Ambystoma mexicanum , Telomerasa , Ambystoma mexicanum/genética , Ambystoma mexicanum/metabolismo , Animales , Secuencia de Bases , Humanos , Regeneración/genética , Telomerasa/genética , Telomerasa/metabolismo , Telómero/metabolismo , Vertebrados/genéticaRESUMEN
Major depressive disorder (MDD) is one of the most prevalent and debilitating psychiatric disorders, with a large number of patients not showing an effective therapeutic response to available treatments. Several biopsychosocial factors, such as stress in childhood and throughout life, and factors related to biological aging, may increase the susceptibility to MDD development. Included in critical biological processes related to aging and underlying biological mechanisms associated with MDD is the shortening of telomeres and changes in telomerase activity. This comprehensive review discusses studies that assessed the length of telomeres or telomerase activity and function in peripheral blood cells and brain tissues of MDD individuals. Also, results from in vitro protocols and animal models of stress and depressive-like behaviors were included. We also expand our discussion to include the role of telomere biology as it relates to other relevant biological mechanisms, such as the hypothalamic-pituitary-adrenal (HPA) axis, oxidative stress, inflammation, genetics, and epigenetic changes. In the text and the discussion, conflicting results in the literature were observed, especially considering the size of telomeres in the central nervous system, on which there are different protocols with divergent results in the literature. Finally, the context of this review is considering cell signaling, transcription factors, and neurotransmission, which are involved in MDD and can be underlying to senescence, telomere shortening, and telomerase functions.
Asunto(s)
Trastorno Depresivo Mayor , Telomerasa , Envejecimiento/genética , Animales , Trastorno Depresivo Mayor/genética , Trastorno Depresivo Mayor/terapia , Humanos , Sistema Hipófiso-Suprarrenal/metabolismo , Telomerasa/genética , Telomerasa/metabolismo , Telómero/genética , Telómero/metabolismoRESUMEN
BACKGROUND: Telomeres are indispensable for genome stability maintenance. They are maintained by the telomere-associated protein complex, which include Ku proteins and a telomerase among others. Here, we investigated a role of Ku80 in Leishmania mexicana. Leishmania is a genus of parasitic protists of the family Trypanosomatidae causing a vector-born disease called leishmaniasis. METHODOLOGY/PRINCIPAL FINDINGS: We used the previously established CRISPR/Cas9 system to mediate ablation of Ku80- and Ku70-encoding genes in L. mexicana. Complete knock-outs of both genes were confirmed by Southern blotting, whole-genome Illumina sequencing, and RT-qPCR. Resulting telomeric phenotypes were subsequently investigated using Southern blotting detection of terminal restriction fragments. The genome integrity in the Ku80- deficient cells was further investigated by whole-genome sequencing. Our work revealed that telomeres in the ΔKu80 L. mexicana are elongated compared to those of the wild type. This is a surprising finding considering that in another model trypanosomatid, Trypanosoma brucei, they are shortened upon ablation of the same gene. A telomere elongation phenotype has been documented in other species and associated with a presence of telomerase-independent alternative telomere lengthening pathway. Our results also showed that Ku80 appears to be not involved in genome stability maintenance in L. mexicana. CONCLUSION/SIGNIFICANCE: Ablation of the Ku proteins in L. mexicana triggers telomere elongation, but does not have an adverse impact on genome integrity.
Asunto(s)
Inestabilidad Genómica , Autoantígeno Ku/metabolismo , Leishmania mexicana/genética , Leishmania mexicana/metabolismo , Proteínas Protozoarias/metabolismo , Telómero/metabolismo , Genoma de Protozoos , Humanos , Autoantígeno Ku/genética , Leishmaniasis Cutánea/parasitología , Proteínas Protozoarias/genética , Telómero/genética , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/metabolismoRESUMEN
Leishmaniases belong to the inglorious group of neglected tropical diseases, presenting different degrees of manifestations severity. It is caused by the transmission of more than 20 species of parasites of the Leishmania genus. Nevertheless, the disease remains on the priority list for developing new treatments, since it affects millions in a vast geographical area, especially low-income people. Molecular biology studies are pioneers in parasitic research with the aim of discovering potential targets for drug development. Among them are the telomeres, DNA-protein structures that play an important role in the long term in cell cycle/survival. Telomeres are the physical ends of eukaryotic chromosomes. Due to their multiple interactions with different proteins that confer a likewise complex dynamic, they have emerged as objects of interest in many medical studies, including studies on leishmaniases. This review aims to gather information and elucidate what we know about the phenomena behind Leishmania spp. telomere maintenance and how it impacts the parasite's cell cycle.
Asunto(s)
Ciclo Celular , Leishmania/citología , Leishmania/enzimología , Telomerasa/metabolismo , Telómero/metabolismo , Humanos , Modelos Biológicos , FilogeniaRESUMEN
Telomeres are aging biomarkers, as they shorten while cells undergo mitosis. The aim of this study was to evaluate whether psychiatric disorders marked by psychological distress lead to alterations to telomere length (TL), corroborating the hypothesis that mental disorders might have a deeper impact on our physiology and aging than it was previously thought. A systematic search of the literature using MeSH descriptors of psychological distress ("Traumatic Stress Disorder" or "Anxiety Disorder" or "depression") and telomere length ("cellular senescence", "oxidative stress" and "telomere") was conducted on PubMed, Cochrane Library and ScienceDirect databases. A total of 56 studies (113,699 patients) measured the TL from individuals diagnosed with anxiety, depression and posttraumatic disorders and compared them with those from healthy subjects. Overall, TL negatively associates with distress-related mental disorders. The possible underlying molecular mechanisms that underly psychiatric diseases to telomere shortening include oxidative stress, inflammation and mitochondrial dysfunction linking. It is still unclear whether psychological distress is either a cause or a consequence of telomere shortening.