RESUMEN

The neuronal excitotoxicity that follows reoxygenation after a hypoxic period may contribute to epilepsy, Alzheimer's disease, Parkinson's disease and various disorders that are related to inadequate supplement of oxygen in neurons. Therefore, counteracting the deleterious effects of post-hypoxic stress is an interesting strategy to treat a large spectrum of neurodegenerative diseases. Here, we show that the expression of the key telomere protecting protein Trf2 decreases in the brain of mice submitted to a post-hypoxic stress. Moreover, downregulating the expression of Terf2 in hippocampal neural cells of unchallenged mice triggers an excitotoxicity-like phenotype including glutamate overexpression and behavioral alterations while overexpressing Terf2 in hippocampal neural cells of mice subjected to a post-hypoxic treatment prevents brain damages. Moreover, Terf2 overexpression in culture neurons counteracts the oxidative stress triggered by glutamate. Finally, we provide evidence that the effect of Terf2 downregulation on excitotoxicity involves Sirt3 repression leading to mitochondrial dysfunction. We propose that increasing the level of Terf2 expression is a potential strategy to reduce post-hypoxic stress damages.

Asunto(s)

Neuronas , Sirtuina 3 , Proteína 2 de Unión a Repeticiones Teloméricas , Animales , Ratones , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Sirtuina 3/metabolismo , Sirtuina 3/genética , Neuronas/metabolismo , Neuronas/patología , Hipocampo/metabolismo , Hipocampo/patología , Estrés Oxidativo , Mitocondrias/metabolismo , Encéfalo/metabolismo , Encéfalo/patología , Hipoxia/metabolismo , Ácido Glutámico/metabolismo , Telómero/metabolismo , Telómero/genética , Masculino

RESUMEN

BACKGROUND & AIMS: Our previous study has demonstrated that Telomeric repeat-binding factor 2-interacting protein 1(Terf2ip), played an important role in hepatic ischemia reperfusion injury. This study is aimed to explore the function and mechanism of Terf2ip in non-alcoholic steatohepatitis (NASH). METHODS: The expression of Terf2ip was detected in liver tissue samples obtained from patients diagnosed with NASH. Mice NASH models were constructed by fed with high-fat diet (HFD) or methionine/choline deficient diet (MCD) in Terf2ip knockout and wild type (WT) mice. To further investigate the role of Terf2ip in NASH, adeno-associated viruses (AAV)-Terf2ip was administrated to mice. RESULTS: We observed a significant down-regulation of Terf2ip levels in the livers of NASH patients and mice NASH models. Terf2ip deficiency was associated with an exacerbation of hepatic steatosis in mice under HFD or MCD. Additionally, Terf2ip deficiency impaired lipophagy and fatty acid oxidation (FAO) in NASH models. Mechanically, we discovered that Terf2ip bound to the promoter region of Sirt1 to regulate Sirt1/AMPK pathway activation. As a result, Terf2ip deficiency was shown to inhibit lipophagy through the AMPK pathway, while the activation of Sirt1 alleviated steatohepatitis in the livers of mice. Finally, re-expression of Terf2ip in hepatocyes alleviated liver steatosis, inflammation, and restored lipophagy. CONCLUSIONS: These results revealed that Terf2ip played a protective role in the progression of NASH through regulating lipophagy and FAO by binding to Sirt1 promoter. Our findings provided a potential therapeutic target for the treatment of NASH.

Asunto(s)

Ácidos Grasos , Ratones Noqueados , Enfermedad del Hígado Graso no Alcohólico , Oxidación-Reducción , Sirtuina 1 , Animales , Humanos , Masculino , Ratones , Proteínas Quinasas Activadas por AMP/metabolismo , Proteínas Quinasas Activadas por AMP/genética , Dieta Alta en Grasa/efectos adversos , Modelos Animales de Enfermedad , Ácidos Grasos/metabolismo , Metabolismo de los Lípidos/genética , Hígado/metabolismo , Hígado/patología , Ratones Endogámicos C57BL , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/genética , Enfermedad del Hígado Graso no Alcohólico/patología , Enfermedad del Hígado Graso no Alcohólico/etiología , Transducción de Señal , Sirtuina 1/metabolismo , Sirtuina 1/genética

RESUMEN

Optic neuritis (ON) is a condition marked by optic nerve inflammation due to various potential triggers. Research indicates a link between telomeres and inflammation, as studies demonstrate that inflammation can lead to increased telomere shortening. Aim: We aimed to determine the associations of telomere-related telomeric repeat binding factor 1 (TERF1) rs1545827, rs10107605, and telomeric repeat binding factor 2 (TERF2) rs251796 polymorphisms and relative leukocyte telomere length (LTL) with the occurrence of ON. Methods: In this research, a total of 73 individuals diagnosed with optic neuritis (ON) were studied and the control group included 170 individuals without any health issues. The DNA samples were obtained from peripheral blood leukocytes, which were purified using the DNA salting-out technique. Real-time polymerase chain reaction (RT-PCR) assessed single-nucleotide polymorphisms (SNPs) and relative leukocyte telomere lengths (LTL). The data obtained were processed and analyzed using the "IBM SPSS Statistics 29.0" program. Results: Our study revealed the following results: in the male group, TERF2 rs251796 (AA, AG, and TT) statistically significantly differed between the long and short telomere group, with frequencies of 65.7%, 22.9%, and 2.0% in long telomeres, compared to 35.1%, 56.8%, and 8.1% in the short telomere group (p = 0.013). The TERF2 rs251796 CT genotype, compared to CC, under the codominant genetic model, was associated with 4.7-fold decreased odds of telomere shortening (p = 0.005). Meanwhile, CT+TT genotypes, compared to CC under the dominant genetic model, were associated with 3.5-fold decreased odds of telomere shortening (p = 0.011). Also, the CT genotype, compared to CC+TT, under the overdominant genetic model, was associated with 4.4-fold decreased odds of telomere shortening (p = 0.004). Conclusions: The current evidence may suggest a protective role of TERF2 rs251796 in the occurrence of ON in men.

RESUMEN

Patients with Philadelphia chromosome-like acute lymphoblastic leukaemia (Ph-like ALL) often face a grim prognosis, with PDGFRB gene fusions being commonly detected in this subgroup. Our study has unveiled a newfound fusion gene, TERF2::PDGFRB, and we have found that patients carrying this fusion gene exhibit sensitivity to dasatinib. Ba/F3 cells harbouring the TERF2::PDGFRB fusion display IL-3-independent cell proliferation through activation of the p-PDGFRB and p-STAT5 signalling pathways. These cells exhibit reduced apoptosis and demonstrate sensitivity to imatinib in vitro. When transfused into mice, Ba/F3 cells with the TERF2::PDGFRB fusion gene induce tumorigenesis and a shortened lifespan in cell-derived graft models, but this outcome can be improved with imatinib treatment. In summary, we have identified the novel TERF2::PDGFRB fusion gene, which exhibits oncogenic potential both in vitro and in vivo, making it a potential therapeutic target for tyrosine kinase inhibitors (TKIs).

Asunto(s)

Proteínas de Fusión Oncogénica , Leucemia-Linfoma Linfoblástico de Células Precursoras , Receptor beta de Factor de Crecimiento Derivado de Plaquetas , Proteína 2 de Unión a Repeticiones Teloméricas , Animales , Humanos , Ratones , Carcinogénesis , Transformación Celular Neoplásica , Mesilato de Imatinib , Inhibidores de Proteínas Quinasas/farmacología , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/genética , Transducción de Señal , Factor de Transcripción STAT5/genética , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Proteínas de Fusión Oncogénica/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética

RESUMEN

In this study, we examined 130 patients with pituitary adenomas (PAs) and 320 healthy subjects, using DNA samples from peripheral blood leukocytes purified through the DNA salting-out method. Real-time polymerase chain reaction (RT-PCR) was used to assess single nucleotide polymorphisms (SNPs) and relative leukocyte telomere lengths (RLTLs), while enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of TERF1, TERF2, TNKS2, CTC1, and ZNF676 in blood serum. Our findings reveal several significant associations. Genetic associations with pituitary adenoma occurrence: the TERF1 rs1545827 CT + TT genotypes were linked to 2.9-fold decreased odds of PA occurrence. Conversely, the TNKS2 rs10509637 GG genotype showed 6.5-fold increased odds of PA occurrence. Gender-specific genetic associations with PA occurrence: in females, the TERF1 rs1545827 CC + TT genotypes indicated 3.1-fold decreased odds of PA occurrence, while the TNKS2 rs10509637 AA genotype was associated with 4.6-fold increased odds. In males, the presence of the TERF1 rs1545827 T allele was associated with 2.2-fold decreased odds of PA occurrence, while the TNKS2 rs10509637 AA genotype was linked to a substantial 10.6-fold increase in odds. Associations with pituitary adenoma recurrence: the TNKS2 rs10509637 AA genotype was associated with 4.2-fold increased odds of PA recurrence. On the other hand, the TERF1 rs1545827 CT + TT genotypes were linked to 3.5-fold decreased odds of PA without recurrence, while the TNKS2 rs10509637 AA genotype was associated with 6.4-fold increased odds of PA without recurrence. Serum TERF2 and TERF1 levels: patients with PA exhibited elevated serum TERF2 levels compared to the reference group. Conversely, patients with PA had decreased TERF1 serum levels compared to the reference group. Relative leukocyte telomere length (RLTL): a significant difference in RLTL between the PA group and the reference group was observed, with PA patients having longer telomeres. Genetic associations with telomere shortening: the TERF1 rs1545827 T allele was associated with 1.4-fold decreased odds of telomere shortening. In contrast, the CTC1 rs3027234 TT genotype was linked to 4.8-fold increased odds of telomere shortening. These findings suggest a complex interplay between genetic factors, telomere length, and pituitary adenoma occurrence and recurrence, with potential gender-specific effects. Furthermore, variations in TERF1 and TNKS2 genes may play crucial roles in telomere length regulation and disease susceptibility.

RESUMEN

Myocardial damage is a critical complication and a significant contributor to mortality in sepsis. MicroRNAs (miRNAs) have emerged as key players in sepsis pathogenesis. In this study, we explore the effect and mechanisms of miR-29b-1-5p on sepsis-induced myocardial damage. Sepsis-associated Gene Expression Omnibus datasets (GSE72380 and GSE29914) are examined for differential miRNAs. The mouse sepsis-induced cardiac injury was established by Lipopolysaccharide (LPS) or cecal ligation and puncture (CLP). LPS-treated HL-1 mouse cardiomyocytes simulate myocardial injury in vitro. miR-29b-1-5p is co-upregulated in both datasets and in cardiac tissue from sepsis mouse and HL-1 cell models. miR-29b-1-5p expression downregulation was achieved by antagomir transduction and confirmed by real-time quantitative reverse transcription PCR. Survival analysis and echocardiography examination show that miR-29b-1-5p inhibition improves mice survival cardiac function in LPS- and CLP-induced sepsis mice. Hematoxylin and eosin and Masson's trichrome staining and Immunohistochemistry analysis of mouse myocardial α-smooth muscle actin show that miR-29b-1-5p inhibition reduces myocardial tissue injury and fibrosis. The inflammatory cytokines and cardiac troponin I (cTnI) levels in mouse serum and HL-1 cells are also decreased by miR-29b-1-5p inhibition, as revealed by enzyme-linked immunosorbent assay. The expressions of autophagy-lysosomal pathway-related and apoptosis-related proteins in the mouse cardiac tissues and HL-1 cells are evaluated by western blot analysis. The sepsis-induced activation of the autophagy-lysosomal pathway and apoptosis are also reversed by miR-29b-1-5p antagomir. MTT and flow cytometry measurement further confirm the protective role of miR-29b-1-5p antagomir in HL-1 cells by increasing cell viability and suppressing cell apoptosis. Metascape functionally enriches TargetScan-predicted miR-29b-1-5p target genes. TargetScan prediction and dual luciferase assay validate the targeting relationship between miR-29b-1-5p and telomeric repeat-binding factor 2 (TERF2). The expression and function of TERF2 in HL-1 cells and mice are also evaluated. MiR-29b-1-5p negatively regulates the target gene TERF2. TERF2 knockdown partly restores miR-29b-1-5p antagomir function in LPS-stimulated HL-1 cells. In summary, miR-29b-1-5p targetedly inhibits TERF2, thereby enhancing sepsis-induced myocardial injury.

Asunto(s)

MicroARNs , Sepsis , Ratones , Animales , Lipopolisacáridos/farmacología , Antagomirs , MicroARNs/genética , MicroARNs/metabolismo , Regulación hacia Abajo , Sepsis/complicaciones , Sepsis/genética , Sepsis/metabolismo

RESUMEN

Telomeres are chromosome protectors that shorten during eukaryotic cell replication and in stressful conditions. Developing individuals are susceptible to telomere erosion when their growth is fast and resources are limited. This is critical because the rate of telomere attrition in early life is linked to health and life span of adults. The metabolic telomere attrition hypothesis (MeTA) suggests that telomere dynamics can respond to biochemical signals conveying information about the organism's energetic state. Among these signals are glucocorticoids, hormones that promote catabolic processes, potentially impairing costly telomere maintenance, and nucleotides, which activate anabolic pathways through the cellular enzyme target of rapamycin (TOR), thus preventing telomere attrition. During the energetically demanding growth phase, the regulation of telomeres in response to two contrasting signals - one promoting telomere maintenance and the other attrition - provides an ideal experimental setting to test the MeTA. We studied nestlings of a rapidly developing free-living passerine, the great tit (Parus major), that either received glucocorticoids (Cort-chicks), nucleotides (Nuc-chicks) or a combination of both (NucCort-chicks), comparing these with controls (Cnt-chicks). As expected, Cort-chicks showed telomere attrition, while NucCort- and Nuc-chicks did not. NucCort-chicks was the only group showing increased expression of a proxy for TOR activation (the gene TELO2), of mitochondrial enzymes linked to ATP production (cytochrome oxidase and ATP-synthase) and a higher efficiency in aerobically producing ATP. NucCort-chicks had also a higher expression of telomere maintenance genes (shelterin protein TERF2 and telomerase TERT) and of enzymatic antioxidant genes (glutathione peroxidase and superoxide dismutase). The findings show that nucleotide availability is crucial for preventing telomere erosion during fast growth in stressful environments.

Asunto(s)

Passeriformes , Telómero , Humanos , Animales , Adulto , Telómero/genética , Glucocorticoides , Nucleótidos , Passeriformes/genética , Adenosina Trifosfato , Acortamiento del Telómero

RESUMEN

Alzheimer's disease (AD) is an age-related disorder that results in progressive cognitive impairment and memory loss. Deposition of amyloid ß (Aß) peptides in senile plaques is a hallmark of AD. γ-secretase produces Aß peptides, mostly as the soluble Aß40 with fewer insoluble Aß42 peptides. Rare, early-onset AD (EOAD) occurs in individuals under 60 years of age. Most EOAD cases are due to unknown genetic causes, but a subset is due to mutations in the genes encoding the amyloid precursor protein that is processed into Aß peptides or the presenilins (PS1 and PS2) that process APP. PS1 interacts with the epsilon isoform of glial fibrillary acidic protein (GFAPɛ), a protein found in the subventricular zone of the brain. We have found that GFAPɛ interacts with the telomere protection factor RAP1 (TERF2IP). RAP1 can also interact with PS1 alone or with GFAPɛ in vitro. Our data show that the nuclear protein RAP1 has an extratelomeric role in the cytoplasm through its interactions with GFAPɛ and PS1. GFAPɛ coprecipitated with RAP1 from human cell extracts. RAP1, GFAPɛ, and PS1 all colocalized in human SH-SY5Y cells. Using a genetic model of the γ-secretase complex in Saccharomyces cerevisiae, RAP1 increased γ-secretase activity, and this was potentiated by GFAPɛ. Our studies are the first to connect RAP1 with an age-related disorder.

Asunto(s)

Enfermedad de Alzheimer , Neuroblastoma , Proteínas de Saccharomyces cerevisiae , Humanos , Enfermedad de Alzheimer/genética , Péptidos beta-Amiloides/genética , Secretasas de la Proteína Precursora del Amiloide/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Proteína Ácida Fibrilar de la Glía/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Complejo Shelterina , Proteínas de Unión a Telómeros/genética , Factores de Transcripción/genética

RESUMEN

Background: Spitzoid morphology in familial melanoma has been associated with germline variants in POT1, a telomere maintenance gene (TMG), suggesting a link between telomere biology and spitzoid differentiation. Objective: To assess if familial melanoma cases associated with germline variants in TMG (POT1, ACD, TERF2IP, and TERT) commonly exhibit spitzoid morphology. Methods: In this case series, melanomas were classified as having spitzoid morphology if at least 3 of 4 dermatopathologists reported this finding in ≥25% of tumor cells. Logistic regression was used to calculate odds ratios (OR) of spitzoid morphology compared to familial melanomas from unmatched noncarriers that were previously reviewed by a National Cancer Institute dermatopathologist. Results: Spitzoid morphology was observed in 77% (23 of 30), 75% (3 of 4), 50% (2 of 4), and 50% (1 of 2) of melanomas from individuals with germline variants in POT1, TERF2IP, ACD, and TERT, respectively. Compared to noncarriers (n = 139 melanomas), POT1 carriers (OR = 225.1, 95% confidence interval: 51.7-980.5; P < .001) and individuals with TERF2IP, ACD, and TERT variants (OR = 82.4, 95% confidence interval: 21.3-494.6; P < .001) had increased odds of spitzoid morphology. Limitations: Findings may not be generalizable to nonfamilial melanoma cases. Conclusion: Spitzoid morphology in familial melanoma could suggest germline alteration of TMG.

RESUMEN

TERF2/TRF2 is a pleiotropic telomeric protein that plays a crucial role in tumor formation and progression through several telomere-dependent and -independent mechanisms. Here, we uncovered a novel function for this protein in regulating the macroautophagic/autophagic process upon different stimuli. By using both biochemical and cell biology approaches, we found that TERF2 binds to the non-histone chromatin-associated protein HMGB1, and this interaction is functional to the nuclear/cytoplasmic protein localization. Specifically, silencing of TERF2 alters the redox status of the cells, further exacerbated upon EBSS nutrient starvation, promoting the cytosolic translocation and the autophagic activity of HMGB1. Conversely, overexpression of wild-type TERF2, but not the mutant unable to bind HMGB1, negatively affects the cytosolic translocation of HMGB1, counteracting the stimulatory effect of EBSS starvation. Moreover, genetic depletion of HMGB1 or treatment with inflachromene, a specific inhibitor of its cytosolic translocation, completely abolished the pro-autophagic activity of TERF2 silencing. In conclusion, our data highlighted a novel mechanism through which TERF2 modulates the autophagic process, thus demonstrating the key role of the telomeric protein in regulating a process that is fundamental, under both physiological and pathological conditions, in defining the fate of the cells.Abbreviations: ALs: autolysosomes; ALT: alternative lengthening of telomeres; ATG: autophagy related; ATM: ATM serine/threonine kinase; CQ: Chloroquine; DCFDA: 2',7'-dichlorofluorescein diacetate; DDR: DNA damage response; DHE: dihydroethidium; EBSS: Earle's balanced salt solution; FACS: fluorescence-activated cell sorting; GFP: green fluorescent protein; EGFP: enhanced green fluorescent protein; GSH: reduced glutathione; GSSG: oxidized glutathione; HMGB1: high mobility group box 1; ICM: inflachromene; IF: immunofluorescence; IP: immunoprecipitation; NAC: N-acetyl-L-cysteine; NHEJ: non-homologous end joining; PLA: proximity ligation assay; RFP: red fluorescent protein; ROS: reactive oxygen species; TIF: telomere-induced foci; TERF2/TRF2: telomeric repeat binding factor 2.

Asunto(s)

Proteína HMGB1 , Proteína HMGB1/genética , Daño del ADN , Autofagia/genética , Telómero/metabolismo , Proteínas Nucleares/metabolismo

RESUMEN

Telomere shortening is well known to be associated with ageing. Age is the most decisive risk factor for age-related macular degeneration (AMD) development. The older the individual, the higher the AMD risk. For this reason, we aimed to find any associations between telomere length, distribution of genetic variants in telomere-related genes (TERT, TERT-CLPTM1, TRF1, TRF2, and TNKS2), and serum TERF-1 and TERF2 levels on AMD development. METHODS: Our study enrolled 342 patients with AMD and 177 healthy controls. Samples of DNA from peripheral blood leukocytes were extracted by DNA salting-out method. The genotyping of TERT rs2736098, rs401681 in TERT-CLPTM1 locus, TRF1 rs1545827, rs10107605, TNKS2 rs10509637, rs10509639, and TRF2 rs251796 and relative leukocyte telomere length (T/S) measurement were carried out using the real-time polymerase chain reaction method. Serum TERF-1 and TERF2 levels were measured by enzymatic immunoassay (ELISA). RESULTS: We found longer telomeres in early AMD patients compared to the control group. Additionally, we revealed that minor allele C at TRF1 rs10107605 was associated with decreases the odds of both early and exudative AMD. Each minor allele G at TRF2 rs251796 and TRF1 rs1545827 C/T genotype and C/T+T/T genotypes, compared to the C/C genotype, increases the odds of having shorter telomeres. Furthermore, we found elevated TERF1 serum levels in the early AMD group compared to the control group. CONCLUSIONS: In conclusion, these results suggest that relative leukocyte telomere length and genetic variants of TRF1 and TRF2 play a role in AMD development. Additionally, TERF1 is likely to be associated with early AMD.

Asunto(s)

Degeneración Macular , Tanquirasas , Telomerasa , Humanos , Proteína 1 de Unión a Repeticiones Teloméricas/genética , Proteína 1 de Unión a Repeticiones Teloméricas/metabolismo , Telomerasa/genética , Telomerasa/metabolismo , Leucocitos/metabolismo , Degeneración Macular/genética , ADN

RESUMEN

Mammalian RAP1 (TERF2IP), the most conserved shelterin component, plays a pleiotropic role in the regulation of a variety of cellular processes, including cell metabolism, DNA damage response, and NF-κB signaling, beyond its canonical telomeric role. Moreover, it has been demonstrated to be involved in oncogenesis, progression, and chemoresistance in human cancers. Several mutations and different expression patterns of RAP1 in cancers have been reported. However, the functions and mechanisms of RAP1 in various cancers have not been extensively studied, suggesting the necessity of further investigations. In this review, we summarize the main roles of RAP1 in different mechanisms of cancer development and chemoresistance, with special emphasis on the contribution of RAP1 mutations, expression patterns, and regulation by non-coding RNA, and briefly discuss telomeric and non-telomeric functions.

RESUMEN

BACKGROUND: Drug dependence promotes accelerated aging and higher mortality compare with the general population. Telomere length is a biomarker of determination of cellular aging. Telomere attrition has been reported in heroin dependent patients. To investigate whether telomere length is affected by morphine or not, the expressions of hTERT and TERF2 in morphine treated human SH-SY5Y cells were determined and compared with untreated cells. METHODS: The SH-SY5Y cells were treated with 1 and 5 µM concentrations of morphine for different exposure times (1d, 2d, 3d, 7d and 60 days). The mRNA levels of hTERT and TERF2 were determined using quantitative real-time RCR. The relative telomere length was measured as the ratio of telomere/36B4. RESULTS: The hTERT and TERF2 mRNA levels were down regulated in morphine treated cells as a function of exposure duration. These alterations were reversible if morphine was removed from the culture medium. No reduction in the relative expression of hTERT and TERF2 in the cells exposed to N-acetyl cysteine (NAC) plus morphine was observed. In the SH-SY5Y cells treated by 5 µM morphine for 60 consecutive days, the hTERT and TERF2 mRNA levels and relative telomere lengths remarkably decreased. CONCLUSIONS: Reversible alteration of mRNA levels by removing morphine from culture medium, and effect of NAC in co-treatment of morphine plus NAC, emphasize the role of reactive oxygen species in down-regulation of the expression of hTERT and TERF2 by morphine. Telomere attrition in morphine treated cells is a consequence of down-regulation of the expression of hTERT and TERF2.

Asunto(s)

Telomerasa , Telómero , Regulación hacia Abajo , Humanos , Morfina/farmacología , ARN Mensajero/genética , Telomerasa/genética , Telomerasa/metabolismo , Telómero/genética , Telómero/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas

RESUMEN

Glioblastoma (GBM) is the most aggressive cancer of central nervous system with worst patient outcome. Telomere maintenance is a crucial mechanism governing GBM initiation and progression making it an attractive target. microRNAs (miRNAs) have shown therapeutic potential in GBM. Earlier, we showed miR-490 is downregulated in GBM patients and plays a tumor suppressive role. Here, we show that miR-490 regulates telomere maintenance program in GBM by directly targeting Telomeric Repeat-binding Factor 2 (TERF2) of the shelterin complex, Tankyrase 2 (TNKS2) and Serine/Threonine-protein kinase, SMG1. Overexpression of miR-490 resulted in effects characteristic to hampered telomere maintenance via TERF2 inhibition. These include induction of telomere dysfunction-induced foci and global DNA damage (53BP1 foci), along with an increase in p-γH2AX levels. Further, it led to inhibition of telomere maintenance hallmarks via reduced stemness (SOX2 and SOX4 downregulation) and induction of senescence (H3K9me3 marks gain and SIRT1 downregulation). It also initiated downstream DNA damage response (DDR) leading to p53 pathway activation. Moreover, microarray data analysis highlighted an overlap between miR-490 expression and REST-inhibition responses in GBM. Thus, miR-490-mediated targeting of telomere maintenance could be therapeutically important in GBM.

Asunto(s)

Neoplasias Encefálicas/genética , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Glioblastoma/genética , MicroARNs/genética , Homeostasis del Telómero/genética , Regiones no Traducidas 3'/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Glioblastoma/metabolismo , Glioblastoma/patología , Humanos , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Factores de Transcripción SOXB1/genética , Factores de Transcripción SOXB1/metabolismo , Factores de Transcripción SOXC/genética , Factores de Transcripción SOXC/metabolismo , Tanquirasas/genética , Tanquirasas/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo

RESUMEN

BACKGROUND: Disturbed flow (d-flow)-induced senescence and activation of endothelial cells (ECs) have been suggested to have critical roles in promoting atherosclerosis. Telomeric repeat-binding factor 2 (TERF2)-interacting protein (TERF2IP), a member of the shelterin complex at the telomere, regulates the senescence-associated secretory phenotype (SASP), in which EC activation and senescence are engendered simultaneously by p90RSK-induced phosphorylation of TERF2IP S205 and subsequent nuclear export of the TERF2IP-TERF2 complex. In this study, we investigated TERF2IP-dependent gene expression and its role in regulating d-flow-induced SASP. METHODS: A principal component analysis and hierarchical clustering were used to identify genes whose expression is regulated by TERF2IP in ECs under d-flow conditions. Senescence was determined by reduced telomere length, increased p53 and p21 expression, and increased apoptosis; EC activation was detected by NF-κB activation and the expression of adhesion molecules. The involvement of TERF2IP S205 phosphorylation in d-flow-induced SASP was assessed by depletion of TERF2IP and mutation of the phosphorylation site. RESULTS: Our unbiased transcriptome analysis showed that TERF2IP caused alteration in the expression of a distinct set of genes, including rapamycin-insensitive companion of mTOR (RICTOR) and makorin-1 (MKRN1) ubiquitin E3 ligase, under d-flow conditions. In particular, both depletion of TERF2IP and overexpression of the TERF2IP S205A phosphorylation site mutant in ECs increased the d-flow and p90RSK-induced MKRN1 expression and subsequently inhibited apoptosis, telomere shortening, and NF-κB activation in ECs via suppression of p53, p21, and telomerase (TERT) induction. CONCLUSIONS: MKRN1 and RICTOR belong to a distinct reciprocal gene set that is both negatively and positively regulated by p90RSK. TERF2IP S205 phosphorylation, a downstream event of p90RSK activation, uniquely inhibits MKRN1 expression and contributes to EC activation and senescence, which are key events for atherogenesis.

Asunto(s)

Senescencia Celular , Células Endoteliales/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Células Endoteliales de la Vena Umbilical Humana , Humanos , MicroARNs/genética , Proteínas del Tejido Nervioso/genética , Fosforilación , Unión Proteica , Proteína Asociada al mTOR Insensible a la Rapamicina/genética , Ribonucleoproteínas/genética , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo

RESUMEN

TRF2 (TERF2) binds to telomeric repeats and is critical for telomere integrity. Evidence suggests that it also localizes to non-telomeric DNA damage sites. However, this recruitment appears to be precarious and functionally controversial. We find that TRF2 recruitment to damage sites occurs by a two-step mechanism: the initial rapid recruitment (phase I), and stable and prolonged association with damage sites (phase II). Phase I is poly(ADP-ribose) polymerase (PARP)-dependent and requires the N-terminal basic domain. The phase II recruitment requires the C-terminal MYB/SANT domain and the iDDR region in the hinge domain, which is mediated by the MRE11 complex and is stimulated by TERT. PARP-dependent recruitment of intrinsically disordered proteins contributes to transient displacement of TRF2 that separates two phases. TRF2 binds to I-PpoI-induced DNA double-strand break sites, which is enhanced by the presence of complex damage and is dependent on PARP and the MRE11 complex. TRF2 depletion affects non-sister chromatid homologous recombination repair, but not homologous recombination between sister chromatids or non-homologous end-joining pathways. Our results demonstrate a unique recruitment mechanism and function of TRF2 at non-telomeric DNA damage sites.

Asunto(s)

Cromátides/metabolismo , Daño del ADN , Reparación del ADN por Recombinación , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Línea Celular Tumoral , Cromátides/genética , Activación Enzimática , Células HeLa , Humanos , Poli(ADP-Ribosa) Polimerasas/metabolismo , Telomerasa/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo

RESUMEN

The ASBMB 2018 Bert and Natalie Vallee award in Biomedical Sciences honors our work on shelterin, a protein complex that helps cells distinguish the chromosome ends from sites of DNA damage. Shelterin protects telomeres from all aspects of the DNA damage response, including ATM and ATR serine/threonine kinase signaling and several forms of double-strand break repair. Today, this six-subunit protein complex could easily be identified in one single proteomics step. But, it took us more than 15 years to piece together the entire shelterin complex, one protein at a time. Although we did a lot of things right, here I tell the story of shelterin's discovery with an emphasis on the things that I got wrong along the way.

Asunto(s)

Distinciones y Premios , Investigación Biomédica , Proteínas de Unión a Telómeros/metabolismo , Telómero/metabolismo , Daño del ADN , Reparación del ADN , Humanos , Unión Proteica , Complejo Shelterina , Proteínas de Unión a Telómeros/genética

RESUMEN

Telomere length (TL) is maintained by telomere capping protein complex called shelterin complex. We studied the possible involvement and biomarker potential of shelterin complex molecules in naive multiple myeloma (MM) patients and controls. TL, relative telomerase activity (RTA), real-time PCR and Western blotting were performed in bonemarrow sample of 70 study subjects (patients = 50; controls = 20). Significantly lowered mean TL, increased RTA and higher mRNA expression of shelterin molecules were observed in patients, while PIN2/TERF1 interacting telomerase inhibitor 1 (PINX1) showed lower mRNA expression. Significantly increased protein expression of telomeric repeat binding factor 2 (TERF2), protection of telomeres 1, adrenocortical dysplasia homolog, Tankyrase 1 and telomere reverse transcriptase were observed in MM patients. Significant correlation was observed among genes and of genes with clinical parameters. In conclusion, our findings showed alteration of these molecules at mRNA and protein levels suggested their involvement in disease progression. Optimal sensitivity and specificity of TERF2 and RTA on receiver operating characteristics curve analysis and univariate analysis demonstrated their biomarkers potential in better prediction of disease course.

Asunto(s)

Biomarcadores de Tumor , Mieloma Múltiple/metabolismo , Telómero/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo , Adulto , Anciano , Biopsia , Médula Ósea/patología , Estudios de Casos y Controles , Activación Enzimática , Expresión Génica , Humanos , Persona de Mediana Edad , Mieloma Múltiple/genética , Mieloma Múltiple/mortalidad , Mieloma Múltiple/patología , Estadificación de Neoplasias , Pronóstico , Telómero/genética , Homeostasis del Telómero , Adulto Joven

RESUMEN

Telomeric repeat factor 2 (known as TRF2 or TERF2) is a key component of telomere protection protein complex named as Shelterin. TRF2 helps the folding of telomere to form T-loop structure and the suppression of ATM-dependent DNA damage response activation. TRF2 has been recognized as a potentially new therapeutic target for cancer treatment. In our routine screening of small molecule libraries, we found that Curcusone C had significant effect in disrupting the binding between TRF2 and telomeric DNA, with potent antitumor activity against cancer cells. Our result showed that Curcusone C could bind with TRF2 without binding interaction with TRF1 (telomeric repeat factor 1) although these two proteins share high sequence homology, indicating that their binding conformations and biological functions in telomere could be different. Our mechanistic studies showed that Curcusone C bound with TRF2 possibly through its DNA binding site causing blockage of its interaction with telomeric DNA. Further in cellular studies indicated that the interaction of TRF2 with Curcusone C could activate DNA-damage response, inhibit tumor cell proliferation, and cause cell cycle arrest, resulting in tumor cell apoptosis. Our studies showed that Curcusone C could become a promising lead compound for further development for cancer treatment. Here, TRF2 was firstly identified as a target of Curcusone C. It is likely that the anti-cancer activity of some other terpenes and terpenoids are related with their possible effect for telomere protection proteins.

Asunto(s)

Antineoplásicos Fitogénicos/farmacología , ADN de Neoplasias/genética , Diterpenos/farmacología , Regulación Neoplásica de la Expresión Génica , Telómero/efectos de los fármacos , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Antineoplásicos Fitogénicos/aislamiento & purificación , Sitios de Unión , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , ADN de Neoplasias/metabolismo , Diterpenos/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Células Epiteliales/citología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Células HeLa , Humanos , Especificidad de Órganos , Unión Proteica , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transducción de Señal , Telómero/química , Proteína 1 de Unión a Repeticiones Teloméricas/genética , Proteína 1 de Unión a Repeticiones Teloméricas/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/antagonistas & inhibidores , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo

RESUMEN

Purpose - to explore the role of radiation dose on gene regulation of telomere length and its influence on the patho-genesis of cerebrovascular neurocognitive deficit at the remote period of low-dose irradiation as a result of the Chornobyl accident. Materials and methods. We performed a study of TERF1, TERF2 and TERT genes expression (GE) by RT-PCR, and relative telomere length (RTL) by flow-FISH in 258 clean-up workers of Chornobyl accident divided by radiation dose groups (range 22-2800 mSv) and 78 controls with vascular cognitive deficit. Detailed psychometric interviews were performed to obtain quantitative data on the stage of cognitive deficit. Results. Statistically significant telomere shortening was demonstrated in groups of clean-up workers with radiation doses in 100-250 mSv and 250-500 mSv range (subsequently M ± SD: 15.85 ± 0.27; p< 0.02; 15.89 ± 0,33; p< 0.02; control: 17.21 ± 0,23). A decrease in RTL was in parallel to radiation dose increase and overexpression of negative telomere length regulators: TERF2 genes and, to a lesser extent TERF1; the opposite tendency was demonstrated for TERT GE. In exposed over 500 mSv a significant TERT overexpression was combined with decreased TERF1 and TERF2 GE, and absence of significant RTL changes in comparison with clean-up workers exposed to lower doses indicating a certain independency between gene expression and telomere length changes and possible threshold effects at this dose range. Analysis of the group of exposed in comparison with non-exposed demonstrated a significant decrease (p = 0.03) both of the mean MMSE and RTL parameters suggesting influence of previous exposure. Conclusion. This study shows parallel changes in decline of cognitive function and telomere length and differences in TERF2, TERT and TERF1 gene regulation at the late period after low dose and over 500 mSv exposure.