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1.
J Cancer Res Clin Oncol ; 150(7): 353, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39012375

RESUMO

This article presents an in-depth exploration of the roles of Telomere Repeat-binding Factors 1 and 2 (TRF1 and TRF2), and the shelterin complex, in the context of cancer biology. It emphasizes their emerging significance as potential biomarkers and targets for therapeutic intervention. Central to the shelterin complex, TRF1 and TRF2 are crucial in maintaining telomere integrity and genomic stability, their dysregulation often being a hallmark of cancerous cells. The article delves into the diagnostic and prognostic capabilities of TRF1 and TRF2 across various cancer types, highlighting their sensitivity and specificity. Furthermore, it reviews current strides in drug discovery targeting the shelterin complex, detailing specific compounds and their modes of action. The review candidly addresses the challenges in developing therapies aimed at the shelterin complex, including drug resistance, off-target effects, and issues in drug delivery. By synthesizing recent research findings, the article sheds light on the intricate relationship between telomere biology and cancer development. It underscores the urgency for continued research to navigate the existing challenges and fully leverage the therapeutic potential of TRF1, TRF2, and the shelterin complex in the realm of cancer treatment.


Assuntos
Neoplasias , Telômero , Proteína 1 de Ligação a Repetições Teloméricas , Proteína 2 de Ligação a Repetições Teloméricas , Humanos , Neoplasias/genética , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/terapia , Proteína 2 de Ligação a Repetições Teloméricas/metabolismo , Proteína 2 de Ligação a Repetições Teloméricas/genética , Proteína 1 de Ligação a Repetições Teloméricas/metabolismo , Proteína 1 de Ligação a Repetições Teloméricas/genética , Telômero/metabolismo , Terapia de Alvo Molecular/métodos , Antineoplásicos/uso terapêutico , Antineoplásicos/farmacologia , Complexo Shelterina , Proteínas de Ligação a Telômeros
2.
Drug Discov Today ; 29(8): 104056, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38844065

RESUMO

As a global health challenge, cancer prompts continuous exploration for innovative therapies that are also based on new targets. One promising avenue is targeting the shelterin protein complex, a safeguard for telomeres crucial in preventing DNA damage. The role of shelterin in modulating ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia and Rad3-related (ATR) kinases, key players in the DNA damage response (DDR), establishes its significance in cancer cells. Disrupting these defence mechanisms of shelterins, especially in cancer cells, renders telomeres vulnerable, potentially leading to genomic instability and hindering cancer cell survival. In this review, we outline recent approaches exploring shelterins as potential anticancer targets, highlighting the prospect of developing selective molecules to exploit telomere vulnerabilities toward new innovative cancer treatments.


Assuntos
Antineoplásicos , Neoplasias , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Antineoplásicos/uso terapêutico , Antineoplásicos/farmacologia , Animais , Terapia de Alvo Molecular , Dano ao DNA , Proteínas de Ligação a Telômeros/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Telômero/metabolismo , Complexo Shelterina
4.
Environ Res ; 250: 118515, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38373547

RESUMO

Telomeres are inert DNA sequences (TTAGGG) at the end of chromosomes that protect genetic information and maintain DNA integrity. Emerging evidence has demonstrated that telomere alteration can be closely related to occupational exposure and the development of various disease conditions, including cancer. However, the functions and underlying molecular mechanisms of telomere alteration and shelterin dysregulation after welding fume exposures have not been broadly defined. In this study, we analyzed telomere length and shelterin complex proteins in peripheral blood mononuclear cells (PBMCs) and in lung tissue recovered from male Sprague-Dawley rats following exposure by intratracheal instillation (ITI) to 2 mg/rat of manual metal arc-stainless steel (MMA-SS) welding fume particulate or saline (vehicle control). PBMCs and lung tissue were harvested at 30 d after instillation. Our study identified telomere elongation and shelterin dysregulation in PBMCs and lung tissue after welding fume exposure. Mechanistically, telomere elongation was independent of telomerase reverse transcriptase (TERT) activation. Collectively, our findings demonstrated that welding fume-induced telomere elongation was (a) TERT-independent and (b) associated with shelterin complex dysregulation. It is possible that an alteration of telomere length and its regulatory proteins may be utilized as predictive biomarkers for various disease conditions after welding fume exposure. This needs further investigation.


Assuntos
Pulmão , Ratos Sprague-Dawley , Aço Inoxidável , Telomerase , Soldagem , Animais , Masculino , Ratos , Poluentes Ocupacionais do Ar/toxicidade , Exposição por Inalação/efeitos adversos , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/patologia , Aço Inoxidável/toxicidade , Telomerase/genética , Telomerase/metabolismo , Telômero/efeitos dos fármacos , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo
5.
EMBO J ; 43(1): 87-111, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38177309

RESUMO

Telomere repeat binding factor 2 (TRF2) is an essential component of the telomeres and also plays an important role in a number of other non-telomeric processes. Detailed knowledge of the binding and interaction of TRF2 with telomeric nucleosomes is limited. Here, we study the binding of TRF2 to in vitro-reconstituted kilobasepair-long human telomeric chromatin fibres using electron microscopy, single-molecule force spectroscopy and analytical ultracentrifugation sedimentation velocity. Our electron microscopy results revealed that full-length and N-terminally truncated TRF2 promote the formation of a columnar structure of the fibres with an average width and compaction larger than that induced by the addition of Mg2+, in agreement with the in vivo observations. Single-molecule force spectroscopy showed that TRF2 increases the mechanical and thermodynamic stability of the telomeric fibres when stretched with magnetic tweezers. This was in contrast to the result for fibres reconstituted on the 'Widom 601' high-affinity nucleosome positioning sequence, where minor effects on fibre stability were observed. Overall, TRF2 binding induces and stabilises columnar fibres, which may play an important role in telomere maintenance.


Assuntos
Cromatina , Complexo Shelterina , Proteína 2 de Ligação a Repetições Teloméricas , Humanos , Nucleossomos , Telômero/metabolismo , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo , Proteína 2 de Ligação a Repetições Teloméricas/genética
6.
Heliyon ; 9(10): e20385, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37767490

RESUMO

Maternal stress (MS) during gestation is known to increase the risk for the development of behavioural and physiological disorders and advances cellular aging. In this study, we investigated whether the supplementation of standardized Bacopa monnieri extract (CDRI-08/BME) or l-Carnosine (L-C) to the mother exposed to social stress during gestation modify the effect on their offspring's neurobehaviour, antioxidant defence gene expression, telomere length, and telomere biology. To test this, timed pregnant rats were subjected to social stress during the gestational day (GD) 16-18. A subset of stressed pregnant rats received either BME [80 mg/kg in 0.5% gum acacia (per-orally; p.o)] or L-C [1 mg/kg (p.o)] every day from GD-10 to until their pup's attained postnatal day (PND)-23. We observed that MS induced anxiety-like behaviour, altered inter-limb coordination, antioxidant defence genes [Superoxide dismutase (SOD1,2), Catalase (CAT), Glutathione peroxidase-3 (GPX3)], telomerase reverse transcriptase (TERT), shelterin complex subunits (TRF1, RAP1B, POT1) protein level and shorten telomere length. Notably, supplementation of BME/L-C dampens the MS, thus the effect on neurobehaviour, antioxidant defence gene expression, and telomere biology is minimized in their offspring. Together, our results suggest that supplementation of BME/L-C during gestation dampens the MS and reduced oxidative stress-mediated changes in telomere shortening/biology and associated neurobehaviour in offspring born following MS.

7.
Toxicol In Vitro ; 90: 105608, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37149272

RESUMO

Telomere length may be maintained by telomerase nucleoprotein complex and shelterin complex, namely TRF1, TRF2, TIN2, TPP1, POT1 and RAP1 proteins and modulated by TERRA expression. Telomere loss is observed during progression of chronic myeloid leukemia (CML) from the chronic phase (CML-CP) to the blastic phase (CML-BP). The introduction of tyrosine kinase inhibitors (TKIs), such as imatinib (IM), has changed outcome for majority of patients, however, a number of patients treated with TKIs may develop drug resistance. The molecular mechanisms underlying this phenomenon are not fully understood and require further investigation. In the present study, we demonstrate that IM-resistant BCR::ABL1 gene-positive CML K-562 and MEG-A2 cells are characterized by decreased telomere length, lowered protein levels of TRF2 and RAP1 and increased expression of TERRA in comparison to corresponding IM-sensitive CML cells and BCR::ABL1 gene-negative HL-60 cells. Furthermore, enhanced activity of glycolytic pathway was observed in IM-resistant CML cells. A negative correlation between a telomere length and advanced glycation end products (AGE) was also revealed in CD34+ cells isolated from CML patients. In conclusion, we suggest that affected expression of shelterin complex proteins, namely TRF2 and RAP1, TERRA levels, and glucose consumption rate may promote telomere dysfunction in IM-resistant CML cells.


Assuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva , Complexo Shelterina , Humanos , Mesilato de Imatinib/farmacologia , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo , Proteína 2 de Ligação a Repetições Teloméricas , Telômero/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico
8.
Mol Neurobiol ; 60(8): 4169-4183, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37046137

RESUMO

Telomeres, also known as the "protective caps" of our chromosomes, shorten with each cell cycle due to the end replication problem. This process, termed telomere attrition, is associated with many age-related disorders, such as Alzheimer's disease (AD). Despite the numerous studies conducted in this field, the role of telomere attrition in the onset of the disease remains unclear. To investigate the causal relationship between short telomeres and AD, this review aims to highlight the primary factors that regulate telomere length and maintain its integrity, with an additional outlook on the role of oxidative stress, which is commonly associated with aging and molecular damage. Although some findings thus far might be contradictory, telomere attrition likely plays a crucial role in the progression of AD due to its close association with oxidative stress. The currently available treatments for AD are only symptomatic without affecting the progression of the disease. The components of telomere biology discussed in this paper have previously been studied as an alternative treatment option for several diseases and have exhibited promising in vitro and in vivo results. Hence, this should provide a basis for future research to develop a potential therapeutic strategy for AD. (Created with BioRender.com).


Assuntos
Doença de Alzheimer , Humanos , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Telômero/genética , Telômero/metabolismo , Envelhecimento/genética , Encurtamento do Telômero , Biologia
9.
J Cancer Res Clin Oncol ; 149(10): 7103-7112, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36871092

RESUMO

PURPOSE: Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by recurrent genetic aberration in leukemic stem cells, namely Philadelphia chromosome caused by reciprocal translocation t(9;22)(q34;q11). In our study, we analyzed the telomeric complex expression and function in the molecular pathogenesis of CML. METHODS: We employed CD34+ primary leukemic cells, comprising both leukemic stem and progenitor cell populations, isolated from peripheral blood or bone marrow of CML patients in chronic and blastic phase to analyze the telomere length and telomeric-associated proteins. RESULTS: The reduction in telomere length during disease progression was correlated with increased expression of BCR::ABL1 transcript and the dynamic changes were neither associated with the enzymatic activity of telomerase nor with gene copy number and expression of telomerase subunits. Increased expression of BCR::ABL1 was positively correlated with expression of TRF2, RAP1, TPP1, DKC1, TNKS1, and TNKS2 genes. CONCLUSIONS: The dynamics of telomere length changes in CD34+ CML cells is dependent on the expression level of BCR::ABL, which promotes the expression of certain shelterins including RAP1 and TRF2, as well as TNKS, and TNKS2, and results in telomere shortening regardless of telomerase activity. Our results may allow better understanding of the mechanisms responsible for the genomic instability of leukemic cells and CML progression.


Assuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva , Tanquirases , Telomerase , Humanos , Medula Óssea/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Proteínas Nucleares/genética , Tanquirases/genética , Tanquirases/metabolismo , Telomerase/genética , Telomerase/metabolismo , Telômero/metabolismo
10.
Br Poult Sci ; 64(3): 370-376, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36607418

RESUMO

1. The alterations of relative telomere length and expression of shelterin genes (TRF1, TRF2, RAP1, POT1, and TPP1) were evaluated from the chickens' right heart ventricle in the early and last stages of cold-induced pulmonary hypertension (PHS) at 21 and 42 d of age.2. The relative telomere length in the right ventricular tissues was significantly shorter in the PHS group of broilers than in the control group at 42 d, but did not statistically change at 21 d of age. There was a significant negative correlation between relative telomere length and RV:TV ratio in the broilers at 42 d of age.3. The relative expression of POT1, RAP1 and TPP1 genes in the right ventricular tissues was significantly lower in the PHS group than in the control group at 21 d. The relative expression of the TRF2 gene was only higher in the PHS group of broilers than control at 42 d. The mRNA level of the TRF2 gene exhibited a significant positive correlation with RV:TV ratio at 42 d.4. It was concluded that most shelterin genes are dysregulated in the early stage of PHS (right ventricular hypertrophy) while telomere attrition occurs only at the last stage (heart dilation/failure).


Assuntos
Galinhas , Proteínas de Ligação a Telômeros , Animais , Galinhas/genética , Galinhas/metabolismo , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo , Complexo Shelterina , Telômero/metabolismo , Coração
11.
Mutat Res ; 825: 111797, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36116241

RESUMO

The high level natural radiation areas (HLNRA) of Kerala coast provide unique opportunity to study the biological effect of chronic low dose ionizing radiation (LDIR) on human population below 100 mSv. The radiation level in this area varies from < 1.0-45 mGy /year due to patchy distribution of monazite in the sand, which contains 232Th (8-10%), 238U (0.3%), and their decay products. Telomere length attrition has been correlated to DNA damage due to genotoxic agents. The objective of the present study is to evaluate the effect of natural chronic LDIR exposure on telomere length and transcriptional response of telomere specific and DNA damage repair genes in peripheral blood mononuclear cells (PBMCs) of individuals from normal level natural radiation areas (NLNRA) and HLNRA of Kerala coast, southwest India. Blood samples were collected from 71 random male donors (24-80 years) from NLNRA (≤1.50 mGy/year; N = 19) and two HLNRA dose groups [1.51-10 mGy/year (N = 17); > 10 mGy/year, (N = 35)]. Genomic DNA was isolated from PBMCs and relative telomere length (RTL) was determined using real time q-PCR. Radio-adaptive response (RAR) study was carried out in PBMCs of 40 random males from NLNRA (N = 20) and HLNRA (>10 mGy/year; N = 20), where PBMCs were given a challenged dose of 2.0 Gy gamma radiation at 4 h. Transcriptional profile of telomere specific (TRF1, TRF2, POT1, TIN2, TPP1, RAP1), DNA damage response (RAD17, ATM, CHEK1) and base excision repair pathway (BER) (OGG1, XRCC1, NTH1, NEIL1, MUTYH, MBD4) genes were analysed at basal level and after a challenge dose of 2.0 Gy at 4 h. Our results did not show any significant effect of chronic LDR on RTL among the individuals from NLNRA and two HLNRA groups (p = 0.195). However, influence of age on RTL was clearly evident among NLNRA and HLNRA individuals. At basal level, TRF1, TRF2, TIN2, MBD4, NEIL1 and RAD17 showed significant up-regulation, whereas XRCC1 was significantly down regulated in HLNRA individuals. After a challenge dose of 2.0 Gy, significant transcriptional up-regulation was observed at telomere specific (TRF2, POT1) and BER (MBD4, NEIL1) genes in HLNRA individuals as compared to NLNRA suggesting their role in RAR. In conclusion, elevated level of natural chronic LDR exposure did not have any adverse effect on telomere length in Kerala coast. Significant transcriptional response at TRF2, MBD4 and NEIL1 at basal level and with a challenge dose of 2.0 Gy suggested their active involvement in efficient repair and telomere maintenance in individuals from HLNRA of Kerala coast.


Assuntos
DNA Glicosilases , Exposição à Radiação , Humanos , Masculino , Complexo Shelterina , Leucócitos Mononucleares/efeitos da radiação , Radiação de Fundo , Telômero/genética , Telômero/metabolismo , Exposição à Radiação/efeitos adversos , Proteína 1 Complementadora Cruzada de Reparo de Raio-X/metabolismo , Proteínas de Ciclo Celular/metabolismo , DNA Glicosilases/metabolismo
12.
Biochem Biophys Res Commun ; 617(Pt 1): 22-29, 2022 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-35667242

RESUMO

As the core component of telomeres, the Shelterin complex interacts with telomerase and the CST complex and plays a crucial role in maintaining telomere structure. Perturbation of Shelterin subunits results in telomere damage and subsequent genomic instability, which leads to aging as well as multiple human diseases. Recently, zebrafish have been widely utilized to model human diseases. To establish appropriate zebrafish models of Shelterin-related human disorders, we generated knockout zebrafish of the Shelterin subunit genes acd, pot1, tinf2, terf1 and pinx1 using the CRISPR/Cas9 technology and analyzed the effects of gene deficiency on zebrafish development in detail. We discovered that tinf2, terf1 and pinx1 homozygous mutants could grow to adulthood normally, whereas acd and pot1 homozygous mutant larvae died between 12 and 15 dpf without obvious abnormalities. A few acd-/- mutants survived to adulthood and displayed several premature aging-like phenotypes, including male sterility, cachectic dwarfism and reduced lifespan. Overall, our study established a variety of telomere-deficient zebrafish mutant strains and provided novel animal models for further exploring the relationship between telomeres and aging as well as the pathogenesis of human diseases associated with telomere deficiency.


Assuntos
Telomerase , Peixe-Zebra , Animais , Masculino , Complexo Shelterina , Telomerase/metabolismo , Telômero/genética , Telômero/metabolismo , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/metabolismo
13.
Cancers (Basel) ; 15(1)2022 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-36612286

RESUMO

Telomere length appears to correlate with survival in early non-small-cell lung cancer (NSCLC), but the prognostic impact of telomere status in advanced NSCLC remains undetermined. Our purpose was to evaluate telomere parameters as prognostic and predictive biomarkers in advanced NSCLC. In 79 biopsies obtained before treatment, we analyzed the telomere length and expression of TERT and shelterin complex genes (TRF1, TRF2, POT1, TPP1, RAP1, and TIN2), using quantitative PCR. Non-responders to first-line chemotherapy were characterized by shorter telomeres and low RAP1 expression (p = 0.0035 and p = 0.0069), and tended to show higher TERT levels (p = 0.058). In multivariate analysis, short telomeres were associated with reduced event-free (EFS, p = 0.0023) and overall survival (OS, p = 0.00041). TERT and TRF2 overexpression correlated with poor EFS (p = 0.0069 and p = 0.00041) and OS (p = 0.0051 and p = 0.007). Low RAP1 and TIN2 expression-levels were linked to reduced EFS (p = 0.00032 and p = 0.0069) and OS (p = 0.000051 and p = 0.02). Short telomeres were also associated with decreased survival after nivolumab therapy (p = 0.097). Evaluation of telomere status in advanced NSCLC emerges as a useful biomarker that allows for the selection of patient groups with different clinical evolutions, to establish personalized treatment.

14.
Ageing Res Rev ; 73: 101507, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34736994

RESUMO

Short telomeres confer risk of degenerative diseases. Chronic psychological stress can lead to disease through many pathways, and research from in vitro studies to human longitudinal studies has pointed to stress-induced telomere damage as an important pathway. However, there has not been a comprehensive model to describe how changes in stress physiology and neuroendocrine pathways can lead to changes in telomere biology. Critically short telomeres or the collapse of the telomere structure caused by displacement of telomere binding protein complex shelterin elicit a DNA damage response and lead to senescence or apoptosis. In this narrative review, we summarize the key roles glucocorticoids, reactive oxygen species (ROS) and mitochondria, and inflammation play in mediating the relationship between psychological stress and telomere maintenance. We emphasis that these mediators are interconnected and reinforce each other in positive feedback loops. Telomere length has not been studied across the lifespan yet, but the initial setting point at birth appears to be the most influential point, as it sets the lifetime trajectory, and is influenced by stress. We describe two types of intergenerational stress effects on telomeres - prenatal stress effects on telomeres during fetal development, and 'telotype transmission" -the directly inherited transmission of short telomeres from parental germline. It is clear that the initial simplistic view of telomere length as a mitotic clock has evolved into a far more complex picture of both transgenerational telomere influences, and of interconnected molecular and cellular pathways and networks, as hallmarks of aging where telomere maintenance is a key player interacting with mitochondria. Further mechanistic investigations testing this comprehensive model of stress mediators shaping telomere biology and the telomere-mitochondrial nexus will lead to better understanding from cell to human lifespan aging, and could lead to anti-aging interventions.


Assuntos
Telomerase , Encurtamento do Telômero , Envelhecimento/genética , Senescência Celular , Feminino , Humanos , Mitocôndrias/metabolismo , Gravidez , Espécies Reativas de Oxigênio , Telomerase/metabolismo , Telômero/metabolismo
15.
Int J Mol Sci ; 22(21)2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34769003

RESUMO

While the shelterin complex guards and coordinates the mechanism of telomere regulation, deregulation of this process is tightly linked to malignant transformation and cancer. Here, we present the novel finding of a germline stop-gain variant (p.Q199*) in the shelterin complex gene POT1, which was identified in a child with acute myeloid leukemia. We show that the cells overexpressing the mutated POT1 display increased DNA damage and chromosomal instabilities compared to the wildtype counterpart. Protein and mRNA expression analyses in the primary patient cells further confirm that, physiologically, the variant leads to a nonfunctional POT1 allele in the patient. Subsequent telomere length measurements in the primary cells carrying heterozygous POT1 p.Q199* as well as POT1 knockdown AML cells revealed telomeric elongation as the main functional effect. These results show a connection between POT1 p.Q199* and telomeric dysregulation and highlight POT1 germline deficiency as a predisposition to myeloid malignancies in childhood.


Assuntos
Predisposição Genética para Doença/genética , Leucemia Mieloide Aguda/genética , Transtornos Mieloproliferativos/genética , Complexo Shelterina/genética , Proteínas de Ligação a Telômeros/genética , Adulto , Dano ao DNA/genética , Células Germinativas , Mutação em Linhagem Germinativa/genética , Células HEK293 , Humanos , Células Mieloides , RNA Mensageiro/genética , Telômero/genética , Adulto Jovem
16.
Biochem Biophys Rep ; 26: 100937, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33553693

RESUMO

Telomere encompasses a (TTAGGG)n tandem repeats, and its dysfunction has emerged as the epicenter of driving carcinogenesis by promoting genetic instability. Indeed, they play an essential role in stabilizing chromosomes and therefore protecting them from end-to-end fusion and DNA degradation. Telomere length homeostasis is regulated by several key players including shelterin complex genes, telomerase, and various other regulators. Targeting these regulatory players can be a good approach to combat cancer as telomere length is increasingly correlated with cancer initiation and progression. In this review, we have aimed to describe the telomere length regulator's role in prognostic significance and important drug targets in breast cancer. Moreover, we also assessed alteration in telomeric function by various telomere length regulators and compares this to the regulatory mechanisms that can be associated with clinical biomarkers in cancer. Using publicly available software we summarized mutational and CpG island prediction analysis of the TERT gene breast cancer patient database. Studies have reported that the TERT gene has prognostic significance in breast cancer progression however mechanistic approaches are not defined yet. Interestingly, we reported using the UCSC Xena web-based tool, we confirmed a positive correlation of shelterin complex genes TERF1 and TERF2 in recurrent free survival, indicating the critical role of these genes in breast cancer prognosis. Moreover, the epigenetic landscape of DNA damage repair genes in different breast cancer subtypes also being analyzed using the UCSC Xena database. Together, these datasets provide a comprehensive resource for shelterin complex gene profiles and define epigenetic landscapes of DNA damage repair genes which reveals the key role of shelterin complex genes in breast cancer with the potential to identify novel and actionable targets for treatment.

17.
Adv Exp Med Biol ; 1275: 71-100, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33539012

RESUMO

Abolition of telomerase activity results in telomere shortening, a process that eventually destabilizes the ends of chromosomes, leading to genomic instability and cell growth arrest or death. Telomere shortening leads to the attainment of the "Hayflick limit", and the transition of cells to state of senescence. If senescence is bypassed, cells undergo crisis through loss of checkpoints. This process causes massive cell death concomitant with further telomere shortening and spontaneous telomere fusions. In functional telomere of mammalian cells, DNA contains double-stranded tandem repeats of TTAGGG. The Shelterin complex, which is composed of six different proteins, is required for the regulation of telomere length and stability in cells. Telomere protection by telomeric repeat binding protein 2 (TRF2) is dependent on DNA damage response (DDR) inhibition via formation of T-loop structures. Many protein kinases contribute to the DDR activated cell cycle checkpoint pathways, and prevent DNA replication until damaged DNA is repaired. Thereby, the connection between cell fate and telomere length-associated telomerase activity is regulated by multiple protein kinase activities. Contrarily, inactivation of DNA damage checkpoint protein kinases in senescent cells can restore cell-cycle progression into S phase. Therefore, telomere-initiated senescence is a DNA damage checkpoint response that is activated with a direct contribution from dysfunctional telomeres. In this review, in addition to the above mentioned, the choice of main repair pathways, which comprise non-homologous end joining and homologous recombination in telomere uncapping telomere dysfunctions, are discussed.


Assuntos
Telômero , Proteína 2 de Ligação a Repetições Teloméricas , Animais , Proteínas Mutadas de Ataxia Telangiectasia , Dano ao DNA , Reparo do DNA por Junção de Extremidades , Telômero/genética , Telômero/metabolismo , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo , Proteína 2 de Ligação a Repetições Teloméricas/genética , Proteína 2 de Ligação a Repetições Teloméricas/metabolismo
18.
Pharmacol Ther ; 220: 107742, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33176178

RESUMO

The ends of chromosomes shorten at each round of cell division, and this process is thought to be affected by occupational exposures. Occupational hazards may alter telomere length homeostasis resulting in DNA damage, chromosome aberration, mutations, epigenetic alterations and inflammation. Therefore, for the protection of genetic material, nature has provided a unique nucleoprotein structure known as a telomere. Telomeres provide protection by averting an inappropriate activation of the DNA damage response (DDR) at chromosomal ends and preventing recognition of single and double strand DNA (ssDNA and dsDNA) breaks or chromosomal end-to-end fusion. Telomeres and their interacting six shelterin complex proteins in coordination act as inhibitors of DNA damage machinery by blocking DDR activation at chromosomes, thereby preventing the occurrence of genome instability, perturbed cell cycle, cellular senescence and apoptosis. However, inappropriate DNA repair may result in the inadequate distribution of genetic material during cell division, resulting in the eventual development of tumorigenesis and other pathologies. This article reviews the current literature on the association of changes in telomere length and its interacting proteins with different occupational exposures and the potential application of telomere length or changes in the regulatory proteins as potential biomarkers for exposure and health response, including recent findings and future perspectives.


Assuntos
Saúde Ocupacional , Telômero , Toxicologia , DNA , Humanos , Complexo Shelterina , Telômero/genética , Telômero/metabolismo , Homeostase do Telômero , Proteínas de Ligação a Telômeros
19.
Gene ; 768: 145269, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33148459

RESUMO

Adipose stem cells (ASCs) represent a reliable source of stem cells with a widely demonstrated potential in regenerative medicine and tissue engineering applications. New recent insights suggest that three-dimensional (3D) models may closely mimic the native tissue properties; spheroids from adipose derived stem cells (SASCs) exhibit enhanced regenerative abilities compared with those of 2D models. Stem cell therapy success is determined by "cell-quality"; for this reason, the involvement of stress signals and cellular aging need to be further investigated. Here, we performed a comparative analysis of genes connected with stemness, aging, telomeric length and oxidative stress, in 3D and 2D primary cultures. The expression levels of stemness-related markers and anti-aging Sirtuin1 were significantly up-regulated (P < 0.001) in SASCs-3D while gene expression of aging-related p16INK4a was increased in ASCs-2D (P < 0.001). The 3D and 2D cultures also had a different gene expression profile for genes related to telomere maintenance (Shelterin complex, RNA Binding proteins and DNA repair genes) (P < 0.01 and P < 0.001) and oxidative stress (aldehyde dehydrogenase class1 and 3) (P < 0.05, P < 0.01 and P < 0.001) and presented a striking large variation in their cellular redox state. Based on our findings, we propose a "cell quality" model of SASCs, highlighting a precise molecular expression of several genes involved with stemness (SOX2, POU5F1 and NANOG), anti-aging (SIRT1), oxidative stress (ALDH3) and telomeres maintenance.


Assuntos
Adipócitos/metabolismo , Tecido Adiposo/citologia , Técnicas de Cultura de Células , Transplante de Células-Tronco , Células-Tronco/citologia , Adipócitos/citologia , Adolescente , Adulto , Idoso , Envelhecimento/genética , Adesão Celular/genética , Sobrevivência Celular/genética , Terapia Baseada em Transplante de Células e Tecidos/métodos , Células Cultivadas , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Reparo do DNA/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Oxidativo/genética , Proteínas de Ligação a RNA/metabolismo , Sirtuínas/metabolismo , Esferoides Celulares/citologia , Homeostase do Telômero/genética , Engenharia Tecidual/métodos , Adulto Jovem
20.
J Biomol Struct Dyn ; 39(1): 35-44, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31847782

RESUMO

Protection of telomeres 1 (POT1) is a component of the shelterin complex which is crucial for the regulation of telomere length and maintenance. Many naturally occurring mutations in the POT1 gene have been found to be associated with cardiac angiosarcoma, glioma, familial melanoma, and chronic lymphocytic leukemia. In particular, Y89C is a naturally occurring mutation of POT1, responsible for familial melanoma, and the molecular basis of this mutation is unexplored. In this study, we have extensively analyzed the structure of WT and Y89C mutant of POT1 to see the change in the conformational dynamics, free energy landscape, molecular motions and configurational frustration using molecular dynamics (MD) and other bioinformatics approaches. Y89C mutation shows a significant change in the backbone orientation, compactness, residual fluctuation, solvent accessibility, and hydrogen bonding, suggesting an overall destabilization of the protein structure. Besides, essential dynamics, conformation, magnitude, direction of motion and frustration analysis further suggesting the structural loss in POT1 due to Y89C mutation. Free energy landscape analysis also indicates the presence of a single well-defined free-energy minima in case of WT compared to multiple wells defined free energy minima observed in Y89C, clearly suggesting that this mutation leads to reduce the stability of POT1. This study possibly provides a valuable path to understand the molecular basis of Y89C-mediated development of familial melanoma.Communicated by Ramaswamy H. Sarma.


Assuntos
Melanoma , Neoplasias Cutâneas , Humanos , Melanoma/genética , Mutação , Complexo Shelterina , Telômero/genética , Proteínas de Ligação a Telômeros/genética
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