Telomeres and telomerase: three decades of progress

Suppressing the Aging Phenotype of Mesenchymal Stromal Cells: Are We Ready for Clinical Translation?

Mesenchymal stem/stromal cells (MSCs) are involved in the maintenance and regeneration of a large variety of tissues due to their stemness and multi-lineage differentiation capability. Harnessing these advantageous features, a flurry of clinical trials have focused on MSCs to treat different pathologies, but only few protocols have received regulatory approval so far. Among the various causes hindering MSCs' efficacy is the emergence of cellular senescence, which has been correlated with specific characteristics, such as morphological and epigenetic alterations, DNA damage, ROS production, mitochondrial dysfunction, telomere shortening, non-coding RNAs, loss of proteostasis, and a peculiar senescence-associated secretory phenotype. Several strategies have been investigated for delaying or even hopefully reverting the onset of senescence, as assessed by the senescent phenotype of MSCs. Here, the authors reviewed the most updated literature on the potential causes of senescence, with a particular emphasis on the current and future therapeutic approaches aimed at reverting senescence and/or extending the functional lifespan of stem cells.

AMBRA1 drives gastric cancer progression through regulation of tumor plasticity

Background

Stomach adenocarcinoma (STAD) is an aggressive malignancy characterized by high tumor plasticity and heterogeneity. This study investigates the role of Autophagy and Beclin 1 Regulator 1 (AMBRA1) in regulating tumor plasticity in STAD progression.

Methods

Combined with clinical data, the pan-cancer analysis of AMBRA1 was performed to analyze the role of AMBRA1 in STAD. Western blot, Flow Cytometry (FCM) assay, trans-well assay, wound healing assay, MTT, Reactive Oxygen Species (ROS) assay, Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR) and staining were performed to study the effects of AMBRA1 in AGS human gastric cancer cells. An AGS gastric cancer xenograft model was constructed to further verify the role of AMBRA1 in the development of STAD.

Results

AMBRA1 overexpression correlated with poor overall survival in STAD and was positively associated with T cell CD4+ infiltration. High AMBRA1 expression also indicated worse prognosis in patients with high cancer-associated fibroblast infiltration. AMBRA1 depletion suppressed STAD cell proliferation, migration, and invasion in vitro. Mechanistically, AMBRA1 knockdown induced G1/S cell cycle arrest and triggered cellular senescence through epigenetic alterations, including changes in H3K9me3 levels. AMBRA1 inhibition also sensitized STAD cells to chemotherapeutic agents. In vivo studies confirmed the tumor-suppressive effects of AMBRA1 loss, resulting in reduced tumor growth and increased cellular senescence.

Conclusions

Our findings uncover an oncogenic role for AMBRA1 in STAD. Targeting AMBRA1 may induce tumor cell senescence, apoptosis, and potentiate anti-tumor immunity, providing a rationale for developing AMBRA1-targeted precision therapies to improve clinical outcomes in STAD patients.

Beginning at the ends: telomere and telomere-based cancer therapeutics

Telomeres, which are situated at the terminal ends of chromosomes, undergo a reduction in length with each cellular division, ultimately reaching a critical threshold that triggers cellular senescence. Cancer cells circumvent this senescence by utilizing telomere maintenance mechanisms (TMMs) that grant them a form of immortality. These mechanisms can be categorized into two primary processes: the reactivation of telomerase reverse transcriptase and the alternative lengthening of telomeres (ALT) pathway, which is dependent on homologous recombination (HR). Various strategies have been developed to inhibit telomerase activation in 85-95% of cancers, including the use of antisense oligonucleotides such as small interfering RNAs and endogenous microRNAs, agents that simulate telomere uncapping, expression modulators, immunotherapeutic vaccines targeting telomerase, reverse transcriptase inhibitors, stabilization of G-quadruplex structures, and gene therapy approaches. Conversely, in the remaining 5-15% of human cancers that rely on ALT, mechanisms involve modifications in the chromatin environment surrounding telomeres, upregulation of TERRA long non-coding RNA, enhanced activation of the ataxia telangiectasia and Rad-3-related protein kinase signaling pathway, increased interactions with nuclear receptors, telomere repositioning driven by HR, and recombination events between non-sister chromatids, all of which present potential targets for therapeutic intervention. Additionally, combinatorial therapy has emerged as a strategy that employs selective agents to simultaneously target both telomerase and ALT, aiming for optimal clinical outcomes. Given the critical role of anti-TMM strategies in cancer treatment, this review provides an overview of the latest insights into the structure and function of telomeres, their involvement in tumorigenesis, and the advancements in TMM-based cancer therapies.

Review of hTERT-Immortalized Cells: How to Assess Immortality and Confirm Identity

Cell immortalization has an important role in scientific research, as well as increasing significance in the context of cell therapy and biotechnology. Over the years, many immortalized cell lines have been produced using human telomerase reverse transcriptase (hTERT) alone or in a combination with viral oncogenes. Different hTERT-immortalized cells are commercially available, and numerous papers about obtaining immortalized cell lines have also been published. However, no specific list of characteristics that need to be checked to confirm successful immortalization exists. Most researchers evaluate only a few parameters, while different articles contain various opinions on the assessment of these characteristics. Results also vary significantly between different cell types, which have their own traits depending on their origin and functions. In the current paper, we raise these questions and discuss controversial issues concerning currently available testing methods for immortalization evaluation and the value and the limitations of the approaches. In addition, we propose a protocol for evaluation of hTERT immortalization success consisting of the following important steps: the assessment of the proliferation rate and dividing capacity, cell morphology, phenotype, karyotype stability, telomerase activity, the expression of cell-specific markers, and tumorigenicity. To our opinion, the hTERT expression level, telomere length, and senescence-associated β-galactosidase staining are controversial with regard to the implemented methods, so these parameters may be optional. For all the evaluation steps, we recommend to pay attention to the necessity of comparing the traits of the obtained immortalized and parent cells.

Genotype and Associated Cancer Risk in Individuals With Telomere Biology Disorders

Importance

Telomere biology disorders (TBDs) are inherited cancer-prone bone marrow failure syndromes with differences in morbidity and mortality based on mode of inheritance.

Objective

To quantify cancer risks in TBDs by genetic subgroups.

Design, Setting, and Participants

This longitudinal cohort study of TBDs assessed cancer occurrences from 2002 through 2022. Participants were individuals with a TBD-associated pathogenic germline variant recruited across institutions by self-referral. Data were collected and analyzed through June 30, 2022.

Exposures

The exposure was TBD genotypes, with subgroups defined by inheritance pattern (autosomal-dominant [AD-non-TINF2] vs autosomal-recessive/X-linked [AR/XLR] vs AD-TINF2).

Main Outcomes and Measures

The main outcome was cancer; secondary outcomes included death, or organ transplant. Cumulative cancer incidence was determined considering death or transplant as competing events. Observed:expected (O:E) ratios of cancer before and after any organ transplant were calculated using the National Cancer Institute's Surveillance, Epidemiology, and End Results Program.

Results

Among 230 individuals with TBD (135 [58.7%] male; median [range] age at last follow-up, 34.6 [1.4-82.2] years) included, the risk of cancer was 3-fold higher than the general population (O:E, 3.35 [95% CI, 2.32-4.68]). The highest risk was observed in individuals with AR/XLR (O:E, 19.16 [95% CI, 9.19-35.24]) with a significantly younger cancer onset than in individuals with AD-non-TINF2 (median [range] age, 36.7 [25.2-53.6] years vs 44.5 [32.2-67.5] years; P = .01). The risk of solid tumors was highest in individuals with AR/XLR (O:E = 23.97 [95% CI, 10.96-45.50]), predominantly head and neck squamous cell carcinomas (O:E, 276.00 [95% CI, 75.20-706.67]). Hematologic malignant neoplasm risk was highest in individuals with AD-non-TINF2 (O:E, 9.41 [95% CI, 4.30-17.86]). Solid tumor cumulative incidence increased to 12% for individuals with AR/XLR by age 45 years and to 13% for individuals with AD-non-TINF2 by age 70 years. The cumulative incidence of hematologic malignant neoplasms leveled off at 2% by age 30 years and 19% by age 70 years in individuals with AR/XLR and AD-non-TINF2, respectively. Individuals with AD-TINF2 showed the highest cumulative incidence for transplant or death (49% by age 15 years). Following transplant, individuals with AR/XLR (O:E, 136.11 [95% CI, 54.72-280.44) or AD-TINF2 (O:E, 81.07 [95% CI, 16.72-236.92]) had the highest cancer risk, predominantly young-onset head and neck squamous cell carcinomas (median [range] age, 32.2 [10.5-35.5] years).

Conclusions and Relevance

This cohort study of individuals with TBDs found an increased cancer risk compared with the general population, with the earliest age at onset for individuals with AR/XLR inheritance. Cancer risks increased after organ transplant across all subgroups. These differences in TBD-associated cancer risks by mode of inheritance suggest cancer screening could be tailored by genotype, but additional research is warranted.

Roles of chromatin and genome instability in cellular senescence and their relevance to ageing and related diseases

Ageing is a complex biological process in which a gradual decline in physiological fitness increases susceptibility to diseases such as neurodegenerative disorders and cancer. Cellular senescence, a state of irreversible cell-growth arrest accompanied by functional deterioration, has emerged as a pivotal driver of ageing. In this Review, we discuss how heterochromatin loss, telomere attrition and DNA damage contribute to cellular senescence, ageing and age-related diseases by eliciting genome instability, innate immunity and inflammation. We also discuss how emerging therapeutic strategies could restore heterochromatin stability, maintain telomere integrity and boost the DNA repair capacity, and thus counteract cellular senescence and ageing-associated pathologies. Finally, we outline current research challenges and future directions aimed at better comprehending and delaying ageing.

Exercise to combat cancer: focusing on the ends

Cancer remains a leading cause of death worldwide and although prognosis and survivorship after therapy have improved significantly, current cancer treatments have long-term health consequences. For decades telomerase-mediated telomere maintenance has been an attractive anti-cancer therapeutic target due to its abundance and role in telomere maintenance, pathogenesis, and growth in neoplasms. Telomere maintenance-specific cancer therapies, however, are marred by off-target side effects that must be addressed before they reach clinical practice. Regular exercise training is associated with telomerase-mediated telomere maintenance in normal cells, which is associated with healthy aging. A single bout of endurance exercise training dynamically, but temporarily, increases TERT mRNA and telomerase activity, as well as several molecules that control genomic stability and telomere length (i.e., shelterin and TERRA). Considering the epidemiological findings and accumulating research highlighting that exercise significantly reduces the risk of many types of cancers and the anti-carcinogenic effects of exercise on tumor growth in vitro, investigating the governing molecular mechanisms of telomerase control in context with exercise and cancer may provide important new insights to explain these findings. Specifically, the molecular mechanisms controlling telomerase in both healthy cells and tumors after exercise could reveal novel therapeutic targets for tumor-specific telomere maintenance and offer important evidence that may refine current physical activity and exercise guidelines for all stages of cancer care.

Causal association and shared genetics between telomere length and COVID-19 outcomes: New evidence from the latest large-scale summary statistics

BACKGROUND

Observational studies suggested that leukocyte telomere length (LTL) is shortened in COVID-19 patients. However, the genetic association and causality remained unknown.

METHODS

Based on the genome-wide association of LTL (N = 472,174) and COVID-19 phenotypes (N = 1086,211-2597,856), LDSC and SUPERGNOVA were used to estimate the genetic correlation. Cross-trait GWAS meta-analysis, colocalization, fine-mapping analysis, and transcriptome-wide association study were conducted to explore the shared genetic etiology. Mendelian randomization (MR) was utilized to infer the causality. Upstream and downstream two-step MR was performed to investigate the potential mediating effects.

RESULTS

LDSC identified a significant genetic association between LTL and all COVID-19 phenotypes (rG < 0, p < 0.05). Six significant regions were observed for LTL and COVID-19 susceptibility and hospitalization, respectively. Colocalization analysis found rs144204502, rs34517439, and rs56255908 were shared causal variants between LTL and COVID-19 phenotypes. Numerous biological pathways associated with LTL and COVID-19 outcomes were identified, mainly involved in -immune-related pathways. MR showed that longer LTL was significantly associated with a lower risk of COVID-19 severity (OR [95% CI] = 0.81 [0.71-0.92], p = 1.24 ×10-3) and suggestively associated with lower risks of COVID-19 susceptibility (OR [95% CI] = 0.96 [0.92-1.00], p = 3.44 ×10-2) and COVID-19 hospitalization (OR [95% CI] = 0.89 [0.80-0.98], p = 1.89 ×10-2). LTL partially mediated the effects of BMI, smoking, and education on COVID-19 outcomes. Furthermore, six proteins partially mediated the causality of LTL on COVID-19 outcomes, including BNDF, QPCT, FAS, MPO, SFTPB, and APOF.

CONCLUSIONS

Our findings suggested that shorter LTL was genetically associated with a higher risk of COVID-19 phenotypes, with shared genetic etiology and potential causality.

Techniques for assessing telomere length: A methodological review

Telomeres are located at the ends of chromosomes and have specific sequences with a distinctive structure that safeguards genes. They possess capping structures that protect chromosome ends from fusion events and ensure chromosome stability. Telomeres shorten in length during each cycle of cell division. When this length reaches a certain threshold, it can lead to genomic instability, thus being implicated in various diseases, including cancer and neurodegenerative disorders. The possibility of telomeres serving as a biomarker for aging and age-related disease is being explored, and their significance is still under study. This is because post-mitotic cells, which are mature cells that do not undergo mitosis, do not experience telomere shortening due to age. Instead, other causes, for example, exposure to oxidative stress, can directly damage the telomeres, causing genomic instability. Nonetheless, a general agreement has been established that measuring telomere length offers valuable insights and forms a crucial foundation for analyzing gene expression and epigenetic data. Numerous approaches have been developed to accurately measure telomere lengths. In this review, we summarize various methods and their advantages and limitations for assessing telomere length.

Telomerase RNA component knockout exacerbates Staphylococcus aureus pneumonia by extensive inflammation and dysfunction of T cells

The telomerase RNA component (Terc) constitutes a non-coding RNA critical for telomerase function, commonly associated with aging and pivotal in immunomodulation during inflammation. Our study unveils heightened susceptibility to pneumonia caused by Staphylococcus aureus (S. aureus) in Terc knockout (Tercko/ko) mice compared to both young and old infected counterparts. The exacerbated infection in Tercko/ko mice correlates with heightened inflammation, manifested by elevated interleukin-1β (IL-1β) levels and activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome within the lung. Employing mRNA sequencing methods alongside in vitro analysis of alveolar macrophages (AMs) and T cells, our study elucidates a compelling correlation between Tercko/ko, inflammation, and impaired T cell functionality. Terc deletion results in compromised T cell function, characterized by dysregulation of the T cell receptor and absence of CD247, potentially compromising the host's capacity to mount an effective immune response against S. aureus. This investigation provides insights into the intricate mechanisms governing increased vulnerability to severe pneumonia in the context of Terc deficiency, which might also contribute to aging-related pathologies, while also highlighting the influence of Terc on T cell function.

Evaluating the prognostic potential of telomerase signature in breast cancer through advanced machine learning model

Background

Breast cancer prognosis remains a significant challenge due to the disease's molecular heterogeneity and complexity. Accurate predictive models are critical for improving patient outcomes and tailoring personalized therapies.

Methods

We developed a Machine Learning-assisted Telomerase Signature (MLTS) by integrating multi-omics data from nine independent breast cancer datasets. Using multiple machine learning algorithms, we identified six telomerase-related genes significantly associated with patient survival. The predictive performance of MLTS was evaluated against 66 existing breast cancer prognostic models across diverse cohorts.

Results

The MLTS demonstrated superior predictive accuracy, stability, and reliability compared to other models. Patients with high MLTS scores exhibited increased tumor mutational burden, chromosomal instability, and poor survival outcomes. Single-cell RNA sequencing analysis further revealed higher MLTS scores in aneuploid tumor cells, suggesting a role in cancer progression. Immune profiling indicated distinct tumor microenvironment characteristics associated with MLTS scores, potentially guiding therapeutic decisions.

Conclusions

Our findings highlight the utility of MLTS as a robust prognostic biomarker for breast cancer. The ability of MLTS to predict patient outcomes and its association with key genomic and cellular features underscore its potential as a target for personalized therapy. Future research may focus on integrating MLTS with additional molecular signatures to enhance its clinical application in precision oncology.

Long-telomeropathy is associated with tumor predisposition syndrome

Telomeres protect chromosomal integrity, and telomere length (TL) is influenced by environmental and genetic factors. While short-telomeres are linked to rare telomeropathies, this study explored the hypothesis that a "long-telomeropathy" is associated with a cancer-predisposing syndrome. Using genomic and health data from 113,861 individuals, a trans-ancestry polygenic risk score for TL (PRS TL ) was developed. A phenome-wide association study (PheWAS) identified 65 tumor traits linked to elevated PRS TL . Using this result, a trans-ancestry phenotype risk score for a long-TL (PheRS LTL ) was develop and validated. Rare variant analyses revealed 13 genes associated with PheRS LTL . Individuals who were carriers of these rare variants had a predisposition for long-TL validating original hypothesis. Most of these genes were new to both cancer and telomere biology. In conclusion, this study identified a novel tumor-predisposing syndrome shaped by both common and rare genetic variants, broadening the understanding of telomeropathies to those with a predisposition for long telomeres.

Liquid-liquid Phase Separation in Aging: Novel Insights in the Pathogenesis and Therapeutics

The intricate organization of distinct cellular compartments is paramount for the maintenance of normal biological functions and the orchestration of complex biochemical reactions. These compartments, whether membrane-bound organelles or membraneless structures like Cajal bodies and RNA transport granules, play crucial roles in cellular function. Liquid-liquid phase separation (LLPS) serves as a reversible process that elucidates the genesis of membranelles structures through the self-assembly of biomolecules. LLPS has been implicated in a myriad of physiological and pathological processes, encompassing immune response and tumor genesis. But the association between LLPS and aging has not been clearly clarified. A recent advancement in the realm of aging research involves the introduction of a new edition outlining the twelve hallmarks of aging, categorized into three distinct groups. By delving into the role and mechanism of LLPS in the formation of membraneless structures at a molecular level, this review encapsulates an exploration of the interaction between LLPS and these aging hallmarks, aiming to offer novel perspectives of the intricate mechanisms underlying the aging process and deeper insights into aging therapeutics.

NOP10 predicts poor prognosis and promotes pancreatic cancer progression

BACKGROUND

Telomere shortening and RNA pseudo-uridylation are common features of tumors. NOP10 is a member of the H/ACA snoRNP family, essential for maintaining telomerase activity and RNA pseudouridylation. NOP10 has been indicated to be substantially expressed in tumors such as breast and lung cancers and is associated with poor prognosis. Currently, no investigation exists on NOP10 in pancreatic cancer (PC). This is the first investigation to elucidate the impact on tumorigenesis and prognostic value of NOP10 in pancreatic adenocarcinoma (PAAD).

METHOD

NOP10 expression and its survival prognostic significance were analyzed via clinical PAAD data from the TCGA database and NOP10 expression in other tumors from the GEPIA database. Furthermore, the NOP10 expression and survival prognosis in clinical samples were validated by qRT-PCR. In-vitro experiments were carried out to elucidate the impact of NOP10 on the biological function of PC cells.

RESULTS

It was revealed that NOP10 expression was increased in PC tissues than in the normal pancreatic tissues. High NOP10 expression was markedly linked with poorer prognosis. NOP10 may be involved in focal adhesion, channel activity, cAMP signaling pathway, the interaction of neuroactive ligand-receptor, and cell adhesion molecules cams. NOP10 was associated with the tumour immune microenvironment and drug sensitivity. Down-regulation of NOP10 expression suppressed PC cells' ability to proliferate, migrate, and invade.

CONCLUSIONS

This investigation elucidated the prognostic and predictive importance of NOP10 in PAAD and revealed that NOP10 is associated with poor prognostic features, survival prognosis and TIME. Knockdown of NOP10 inhibits the progression of PAAD.

Characterization and organization of telomeric-linked helicase (tlh) gene families in Fusarium oxysporum

Telomere-linked RecQ helicase (tlh) genes have been reported in several fungi and a choanoflagellate in the regions adjacent to the terminal telomere repeats. In this study, we explored the Telomere-linked RecQ helicase (tlh) genes in four strains of Fusarium oxysporum, offering new insights into their genomic structure, functional motifs, and impact on chromosomal ends. We conducted a comprehensive analysis, comparing the tlh genes of F. oxysporum with those previously identified in other organisms and uncovering significant similarities. Through comparative genomics, we identified conserved protein motifs across these genes, including a TLH domain, C2H2, and RecQ helicase motifs. Our phylogenetic analysis positions the F. oxysporum tlh genes in a cluster with other known tlhs, suggesting a shared evolutionary origin. Mutation analysis revealed a relatively low level of deleterious mutations in tlh gene paralogs, with a notable proportion of full-size structures maintained across strains. Analysis of subtelomeric sequences indicates that a region with almost identical sequences flanks the majority of chromosome ends, termed tlh-containing region (TLHcr), across these strains. The presence of TLHcrs at chromosome ends, either as single entities or in arrays, underscores their potential role in telomere function and genome stability. Our findings provide a detailed examination of tlh genes in four strains of F. oxysporum, laying the groundwork for future studies on their biological significance and evolutionary history in fungal genomes.

Tenebrio molitor (Mealworm) protein as a sustainable dietary strategy to improve health span in D-galactose-induced aged mice

Aging is an irreversible and continuous biological process involving intricate and interconnected mechanisms. The present work is focused on unravelling the anti-aging mechanisms of mealworm protein and protein-enriched fruit bar and vegetable soup in D-galactose-induced aged mice. Mealworm protein and enriched products significantly enhanced body weight, organ indices, and gut health. Behavioral assessments reflected enhanced neuroprotective effects. Mealworm protein and its enriched products demonstrated protective effects through anti-inflammatory activity with the highest reduction of TNFα (17.1 %), IL-6 (55.5 %), and IL-1β (75.1 %) levels and upregulated the anti-inflammatory marker (IL-4). Gene expression studies confirmed the induction of anti-aging effects by promoting metabolism, reducing cellular senescence, and enhancing anti-oxidant enzyme activity. The treatments extended telomere lengths by 3-4 times, further affirming the potential anti-aging efficacy of mealworm protein and its enriched products. Mealworm protein demonstrated positive effects on weight gain, anti-inflammatory responses, and telomere length; while fruit and vegetable products enhanced antioxidant activity, and positively influenced gut health. Further, a synergistic effect was observed by combining them, which resulted in improved overall anti-aging effect. The present work provides valuable insights into the multifaceted anti-aging mechanisms associated with mealworm protein and enriched products, highlighting their potential as functional foods with significant health-promoting effects.

Cellular senescence and its pathogenic and therapeutic implications in autoimmune hepatitis

INTRODUCTION

Senescent cells are characterized by replicative arrest and phenotypes that produce diverse pro-inflammatory and pro-oxidant mediators. The senescence of diverse hepatic cell types could constitute an unrecognized pathogenic mechanism and prognostic determinant in autoimmune hepatitis. The impact of cellular senescence in autoimmune hepatitis is unknown, and it may suggest adjunctive management strategies.

AREAS COVERED

This review describes the molecular mechanisms of cellular senescence, indicates its diagnostic features, suggests its consequences, presents possible therapeutic interventions, and encourages investigations of its pathogenic role and management in autoimmune hepatitis. Treatment prospects include elimination or reversal of senescent cells, generation of ectopic telomerase, reactivation of dormant telomerase, neutralization of specific pro-inflammatory secretory products, and mitigation of the effects of mitochondrial dysfunction.

EXPERT OPINION

The occurrence, nature, and consequences of cellular senescence in autoimmune hepatitis must be determined. The senescence of diverse hepatic cell types could affect the outcome of autoimmune hepatitis by impairing hepatic regeneration, intensifying liver inflammation, and worsening hepatic fibrosis. Cellular senescence could contribute to suboptimal responses during conventional glucocorticoid-based therapy. Interventions that target specific pro-inflammatory products of the senescent phenotype or selectively promote apoptosis of senescent cells may be preferred adjunctive treatments for autoimmune hepatitis depending on the cancer risk.

Mutant ATRX: pathogenesis of ATRX syndrome and cancer

The transcriptional regulator ATRX, a genetic factor, is associated with a range of disabilities, including intellectual, hematopoietic, skeletal, facial, and urogenital disabilities. ATRX mutations substantially contribute to the pathogenesis of ATRX syndrome and are frequently detected in gliomas and many other cancers. These mutations disrupt the organization, subcellular localization, and transcriptional activity of ATRX, leading to chromosomal instability and affecting interactions with key regulatory proteins such as DAXX, EZH2, and TERRA. ATRX also functions as a transcriptional regulator involved in the pathogenesis of neuronal disorders and various diseases. In conclusion, ATRX is a central protein whose abnormalities lead to multiple diseases.

Inherited Telomere Biology Disorders: Pathophysiology, Clinical Presentation, Diagnostics, and Treatment

Background

Telomeres are the end-capping structures of all eukaryotic chromosomes thereby protecting the genome from damage and degradation. During the aging process, telomeres shorten continuously with each cell division until critically short telomeres prevent further proliferation whereby cells undergo terminal differentiation, senescence, or apoptosis. Premature aging due to critically short telomere length (TL) can also result from pathogenic germline variants in the telomerase complex or related genes that typically counteract replicative telomere shortening in germline and certain somatic cell populations, e.g., hematopoetic stem cells. Inherited diseases that result in altered telomere maintenance are summarized under the term telomere biology disorder (TBD).

Summary

Since TL both reflects but more importantly restricts the replicative capacity of various human tissues, a sufficient telomere reserve is particularly important in cells with high proliferative activity (e.g., hematopoiesis, immune cells, intestinal cells, liver, lung, and skin). Consequently, altered telomere maintenance as observed in TBDs typically results in premature replicative cellular exhaustion in the respective organ systems eventually leading to life-threatening complications such as bone marrow failure (BMF), pulmonary fibrosis, and liver cirrhosis.

Key Messages

The recognition of a potential congenital origin in approximately 10% of adult patients with clinical BMF is of utmost importance for the proper diagnosis, appropriate patient and family counseling, to prevent the use of inefficient treatment and to avoid therapy-related toxicities including appropriate donor selection when patients have to undergo stem cell transplantation from related donors. This review summarizes the current state of knowledge about TBDs with particular focus on the clinical manifestation patterns in children (termed early onset TBD) compared to adults (late-onset TBD) including typical treatment- and disease course-related complications as well as their prognosis and adequate therapy. Thereby, it aims to raise awareness for a disease group that is currently still highly underdiagnosed particularly when it first manifests itself in adulthood.

Telomere Length and Telomerase Activity as Potential Biomarkers for Gastrointestinal Cancer

Gastrointestinal (GI) cancers, such as colorectal and gastric cancers, pose significant global health challenges due to their high rates of incidence and mortality. Even with advancements in treatment and early detection, many patients still face poor outcomes, highlighting the critical need for new biomarkers and therapeutic targets. Telomere length (TL) and telomerase activity (TA) have gained attention in this context. Telomeres, protective nucleotide sequences at chromosome ends, shorten with each cell division, leading to cellular aging. Telomerase, a ribonucleoprotein enzyme, counteracts this shortening by adding telomeric repeats, a process tightly regulated in normal cells but often dysregulated in cancer. This review critically evaluates the role of TL and TA in the pathogenesis of GI cancers, examining their potential as diagnostic, prognostic, and predictive biomarkers. It explores how alterations in telomere biology contribute to the initiation and progression of GI tumors and assesses the therapeutic implications of targeting telomerase. By integrating findings from diverse studies, this review aims to elucidate the intricate relationship between telomere dynamics and gastrointestinal carcinogenesis, offering insights into how TL and TA could be leveraged to enhance the early detection, treatment, and prognosis of GI cancers.

Potential protein kinase inhibitors that target G-quadruplex DNA structures in the human telomeric regions

Telomeric regions contain Guanine-rich sequences arranged in a planar manner and connected by Hoogsteen hydrogen bonds that can fold into G-quadruplex (G4) DNA structures, and can be stabilized by monovalent metal cations. The presence of G4 DNA holds significance in cancer-related processes, especially due to their regulatory potential at transcriptional and translational levels of oncogene and tumor suppressor genes. The objective of this current research is to explore the evolving realm of FDA-approved protein kinase inhibitors, with a specific emphasis on their capacity to stabilize the G4 DNA structures formed at the human telomeric regions. This involves investigating the possibility of repurposing FDA-approved protein kinase inhibitors as a novel approach for targeting multiple cancer types. In this context, we have selected 16 telomeric G4 DNA structures as targets and 71 FDA-approved small-molecule protein kinase inhibitors as ligands. To investigate their binding affinities, molecular docking of human telomeric G4 DNA with nuclear protein kinase inhibitors and their corresponding co-crystalized ligands were performed. We found that Ponatinib and Lapatinib interact with all the selected G4 targets, the binding free energy calculations, and molecular dynamic simulations confirm their binding efficacy and stability. Thus, it is hypothesized that Ponatinib and Lapatinib may stabilize human telomeric G4 DNA in addition to their ability to inhibit BCR-ABL and the other members of the EGFR family. As a result, we also hypothesize that the stabilization of G4 DNA might represent an additional underlying mechanism contributing to their efficacy in exerting anti-cancer effects.

NRF2 signaling pathway and telomere length in aging and age-related diseases

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is well recognized as a critical regulator of redox, metabolic, and protein homeostasis, as well as the regulation of inflammation. An age-associated decline in NRF2 activity may allow oxidative stress to remain unmitigated and affect key features associated with the aging phenotype, including telomere shortening. Telomeres, the protective caps of eukaryotic chromosomes, are highly susceptible to oxidative DNA damage, which can accelerate telomere shortening and, consequently, lead to premature senescence and genomic instability. In this review, we explore how the dysregulation of NRF2, coupled with an increase in oxidative stress, might be a major determinant of telomere shortening and age-related diseases. We discuss the relevance of the connection between NRF2 deficiency in aging and telomere attrition, emphasizing the importance of studying this functional link to enhance our understanding of aging pathologies. Finally, we present a number of compounds that possess the ability to restore NRF2 function, maintain a proper redox balance, and preserve telomere length during aging.

Dysfunction of Telomeric Cdc13-Stn1-Ten1 Simultaneously Activates DNA Damage and Spindle Checkpoints

Telomeres, the ends of eukaryotic linear chromosomes, are composed of repeated DNA sequences and specialized proteins, with the conserved telomeric Cdc13/CTC1-Stn1-Ten1 (CST) complex providing chromosome stability via telomere end protection and the regulation of telomerase accessibility. In this study, SIZ1, coding for a SUMO E3 ligase, and TOP2 (a SUMO target for Siz1 and Siz2) were isolated as extragenic suppressors of Saccharomyces cerevisiae CST temperature-sensitive mutants. ten1-sz, stn1-sz and cdc13-sz mutants were isolated next due to being sensitive to intracellular Siz1 dosage. In parallel, strong negative genetic interactions between mutants of CST and septins were identified, with septins being noticeably sumoylated through the action of Siz1. The temperature-sensitive arrest in these new mutants of CST was dependent on the G2/M Mad2-mediated and Bub2-mediated spindle checkpoints as well as on the G2/M Mec1-mediated DNA damage checkpoint. Our data suggest the existence of yet unknown functions of the telomeric Cdc13-Stn1-Ten1 complex associated with mitotic spindle positioning and/or assembly that could be further elucidated by studying these new ten1-sz, stn1-sz and cdc13-sz mutants.

The causal effect of telomere length on the risk of malignant lymphoma: A Mendelian randomization study

Telomere length (TL) has been implicated in the risk assessment of numerous cancers in observational studies. Nevertheless, the relationship between TL and malignant lymphoma remains unclear, displaying inconsistent patterns across different studies. A summary dataset for genome-wide association study of TL and malignant lymphoma was acquired from the OpenGWAS website. An extensive 2-sample Mendelian randomization (MR) analysis was performed, encompassing various methodologies such as MR-Egger, weighted median, weighted mode, simple mode, and the primary method of inverse-variance weighting (IVW). Sensitivity evaluations were performed using the Cochran Q test, MR-Egger regression, and leave-one-out analysis. The main method IVW revealed that TL substantially increased the risk of Hodgkin lymphoma (HL; odds ratio [OR] = 2.135; 95% confidence interval [CI] = 1.181-3.859; P = .012). Both the IVW and weighted median methods indicated statistical associations between genetically predicted TL and other types of non-HL (OR = 1.671, 95% CI = 1.009-2.768, P = .045; OR = 2.310, 95% CI = 1.033-5.169, P = .042). However, there was no association between TL and diffuse large B-cell lymphoma, follicular lymphoma, or mature T/natural Killer-cell lymphoma, and sensitivity analysis revealed no heterogeneity or horizontal pleiotropy, indicating that the causal effect was robust. Our study shows that TL plays different roles in different types of lymphomas. A longer TL significantly increases the risk of HL and other types of non-HL.

Reproductive aging weakens offspring survival and constrains the telomerase response to herpesvirus in Pacific oysters

Telomere length (TL) is increasingly recognized as a molecular marker that reflects how reproductive aging affects intergenerational transmissions. Here, we investigated the effects of parental age on offspring survival and the regulation of TL by examining the telomere-elongating activity of telomerase in the Pacific oyster. We assessed the classical hallmarks of aging in parents at three age classes (young, middle-aged, and old) and crossbred them using a split-brood design to examine the consequences of the nine maternal-by-paternal age combinations on their offspring. Reproductive aging leads to increased larval mortality and accelerated telomere shortening in spats, rendering them more susceptible to infection by the Ostreid herpesvirus. Viral exposure stimulates telomerase activity, a response that we identified as adaptive, but weakened by parental aging. While telomerase lengthens a spat's telomere, paradoxically, longer individual TL predicts higher mortality in adults. The telomerase-telomere complex appeared as a conservative biomarker for distinguishing survivors and losers upon exposure to polymicrobial diseases.

Recent Progress in DNA Biosensors for Detecting Biomarkers in Living Cells

Analysis of biomarkers in living cells is crucial for deciphering the dynamics of cells as well as for precise diagnosis of diseases. DNA biosensors employ DNA sequences as probes to offer insights into living cells, and drive progress in disease diagnosis and drug development. In this review, we present recent advances in DNA biosensors for detecting biomarkers in living cells. The basic structural components of DNA biosensors and the signal output method are presented. The strategies of DNA biosensors crossing the cell membrane are also described, including coincubation, nanocarriers, and nanoelectroporation techniques. Based on biomarker categorization, we detail recent applications of DNA biosensors for detecting small molecules, RNAs, proteins, and integrated targets in living cells. Furthermore, the future development directions of DNA biosensors are summarized to encourage further research in this growing field.

The Role of Molecular and Cellular Aging Pathways on Age-Related Hearing Loss

Aging, a complex process marked by molecular and cellular changes, inevitably influences tissue and organ homeostasis and leads to an increased onset or progression of many chronic diseases and conditions, one of which is age-related hearing loss (ARHL). ARHL, known as presbycusis, is characterized by the gradual and irreversible decline in auditory sensitivity, accompanied by the loss of auditory sensory cells and neurons, and the decline in auditory processing abilities associated with aging. The extended human lifespan achieved by modern medicine simultaneously exposes a rising prevalence of age-related conditions, with ARHL being one of the most significant. While our understanding of the molecular basis for aging has increased over the past three decades, a further understanding of the interrelationship between the key pathways controlling the aging process and the development of ARHL is needed to identify novel targets for the treatment of AHRL. The dysregulation of molecular pathways (AMPK, mTOR, insulin/IGF-1, and sirtuins) and cellular pathways (senescence, autophagy, and oxidative stress) have been shown to contribute to ARHL. However, the mechanistic basis for these pathways in the initiation and progression of ARHL needs to be clarified. Therefore, understanding how longevity pathways are associated with ARHL will directly influence the development of therapeutic strategies to treat or prevent ARHL. This review explores our current understanding of the molecular and cellular mechanisms of aging and hearing loss and their potential to provide new approaches for early diagnosis, prevention, and treatment of ARHL.

Effect of aging and exercise on hTERT expression in thymus tissue of hTERT transgenic bacterial artificial chromosome mice

Telomere shortening occurs with aging in immune cells and may be related to immunosenescence. Exercise can upregulate telomerase activity and attenuate telomere shortening in immune cells, but it is unknown if exercise impacts other immune tissues such as the thymus. This study aimed to examine human telomerase reverse transcriptase (hTERT) alternative splicing (AS) in response to aging and exercise in thymus tissue. Transgenic mice with a human TERT bacterial artificial chromosome integrated into its genome (hTERT-BAC) were utilized in two different exercise models. Mice of different ages were assigned to an exercise cage (running wheel) or not for 3 weeks prior to thymus tissue excision. Middle-aged mice (16 months) were exposed or not to treadmill running (30 min at 60% maximum speed) prior to thymus collection. hTERT transcript variants were measured by RT-PCR. hTERT transcripts decreased with aging (r =  - 0.7511, p < 0.0001) and 3 weeks of wheel running did not counteract this reduction. The ratio of exons 7/8 containing hTERT to total hTERT transcripts increased with aging (r = 0.3669, p = 0.0423) but 3 weeks of voluntary wheel running attenuated this aging-driven effect (r = 0.2013, p = 0.4719). Aging increased the expression of senescence marker p16 with no impact of wheel running. Thymus regeneration transcription factor, Foxn1, went down with age with no impact of wheel running exercise. Acute treadmill exercise did not induce any significant changes in thymus hTERT expression or AS variant ratio (p > 0.05). In summary, thymic hTERT expression is reduced with aging. Exercise counteracted a shift in hTERT AS ratio with age. Our data demonstrate that aging impacts telomerase expression and that exercise impacts dysregulated splicing that occurs with aging.

5-aza-2'-deoxycytidine induces telomere dysfunction in breast cancer cells

AIMS

Azacitidine, a drug that epigenetically modifies DNA, is widely used to treat haematological malignancies. However, at low doses, it demethylates DNA, and as a result, can alter gene expression. In our previous publication, we showed that low doses of azacitidine induce telomere length elongation in breast cancer cells. In this study, we aim to identify the mechanisms which lead to telomere length increases.

METHODS

Breast cancer cell lines representing different molecular sub-types were exposed to 5-aza-2'-deoxycytidine (5-aza) in 2 and 3D cultures, followed by DNA, RNA, and protein extractions. Samples were then analysed for telomere length, DNA damage, telomerase, and ALT activity.

RESULTS

We show that treatment of the cell lines with 5-aza for 72 h induced DNA damage at the telomeres and increased ALT activity 3-fold. We also identified a gene, POLD3, which may be involved in the ALT activity seen after treatment.

CONCLUSION

Our results indicate that while 5-aza is a useful drug for treating haematological cancers, surviving cancer cells that have been exposed to lower doses of the drug may activate mechanisms such as ALT. This could lead to cancer cell survival and possible resistance to 5-aza clinically.

The landscape of lncRNAs in cell granules: Insights into their significance in cancer

Cellular compartmentalization, achieved through membrane-based compartments, is a fundamental aspect of cell biology that contributes to the evolutionary success of cells. While organelles have traditionally been the focus of research, membrane-less organelles (MLOs) are emerging as critical players, exhibiting distinct morphological features and unique molecular compositions. Recent research highlights the pivotal role of long noncoding RNAs (lncRNAs) in MLOs and their involvement in various cellular processes across different organisms. In the context of cancer, dysregulation of MLO formation, influenced by altered lncRNA expression, impacts chromatin organization, oncogenic transcription, signaling pathways, and telomere lengthening. This review synthesizes the current understanding of lncRNA composition within MLOs, delineating their functions and exploring how their dysregulation contributes to human cancers. Environmental challenges in tumorigenesis, such as nutrient deprivation and hypoxia, induce stress granules, promoting cancer cell survival and progression. Advancements in biochemical techniques, particularly single RNA imaging methods, offer valuable tools for studying RNA functions within live cells. However, detecting low-abundance lncRNAs remains challenging due to their limited expression levels. The correlation between lncRNA expression and pathological conditions, particularly cancer, should be explored, emphasizing the importance of single-cell studies for precise biomarker identification and the development of personalized therapeutic strategies. This article is categorized under: RNA Export and Localization > RNA Localization RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.

Understanding, diagnosing, and treating pancreatic cancer from the perspective of telomeres and telomerase

Telomerase is associated with cellular aging, and its presence limits cellular lifespan. Telomerase by preventing telomere shortening can extend the number of cell divisions for cancer cells. In adult pancreatic cells, telomeres gradually shorten, while in precancerous lesions of cancer, telomeres in cells are usually significantly shortened. At this time, telomerase is still in an inactive state, and it is not until before and after the onset of cancer that telomerase is reactivated, causing cancer cells to proliferate. Methylation of the telomerase reverse transcriptase (TERT) promoter and regulation of telomerase by lactate dehydrogenase B (LDHB) is the mechanism of telomerase reactivation in pancreatic cancer. Understanding the role of telomeres and telomerase in pancreatic cancer will help to diagnose and initiate targeted therapy as early as possible. This article reviews the role of telomeres and telomerase as biomarkers in the development of pancreatic cancer and the progress of research on telomeres and telomerase as targets for therapeutic intervention.

Biomolecular condensates and disease pathogenesis

Biomolecular condensates or membraneless organelles (MLOs) formed by liquid-liquid phase separation (LLPS) divide intracellular spaces into discrete compartments for specific functions. Dysregulation of LLPS or aberrant phase transition that disturbs the formation or material states of MLOs is closely correlated with neurodegeneration, tumorigenesis, and many other pathological processes. Herein, we summarize the recent progress in development of methods to monitor phase separation and we discuss the biogenesis and function of MLOs formed through phase separation. We then present emerging proof-of-concept examples regarding the disruption of phase separation homeostasis in a diverse array of clinical conditions including neurodegenerative disorders, hearing loss, cancers, and immunological diseases. Finally, we describe the emerging discovery of chemical modulators of phase separation.

Discovery of telomerase inhibitors: existing strategies and emerging innovations

Telomerase, crucial for maintaining telomere length, is an attractive target for cancer therapy due to its role in cellular immortality. Despite three decades of research efforts, no small-molecule telomerase inhibitors have been clinically approved, highlighting the extensive challenges in developing effective telomerase-based therapeutics. This review examines conventional and emerging methods to measure telomerase activity and discusses existing inhibitors, including oligonucleotides and small molecules. Furthermore, this review highlights recent breakthroughs in structural studies of telomerase using cryo-electron microscopy, which can facilitate improved structure-based drug design. Altogether, advancements in structural methodologies and high-throughput screening offer promising prospects for telomerase-based cancer therapeutic development.

Telomeric DNA breaks in human induced pluripotent stem cells trigger ATR-mediated arrest and telomerase-independent telomere damage repair

Although mechanisms of telomere protection are well-defined in differentiated cells, how stem cells sense and respond to telomere dysfunction, in particular telomeric double-strand breaks (DSBs), is poorly characterized. Here, we report the DNA damage signaling, cell cycle, and transcriptome changes in human induced pluripotent stem cells (iPSCs) in response to telomere-internal DSBs. We engineer human iPSCs with an inducible TRF1-FokI fusion protein to acutely induce DSBs at telomeres. Using this model, we demonstrate that TRF1-FokI DSBs activate an ATR-dependent DNA damage response, which leads to p53-independent cell cycle arrest in G2. Using CRISPR-Cas9 to cripple the catalytic domain of telomerase reverse transcriptase, we show that telomerase is largely dispensable for survival and lengthening of TRF1-FokI-cleaved telomeres, which instead are effectively repaired by robust homologous recombination (HR). In contrast to HR-based telomere maintenance in mouse embryonic stem cells, where HR causes ZSCAN4-dependent extension of telomeres beyond their initial lengths, HR-based repair of telomeric breaks is sufficient to maintain iPSC telomeres at a normal length, which is compatible with sustained survival of the cells over several days of TRF1-FokI induction. Our findings suggest a previously unappreciated role for HR in telomere maintenance in telomerase-positive iPSCs and reveal distinct iPSC-specific responses to targeted telomeric DNA damage.

Association and causal impact of TERT genetic variants on peripheral blood leukocyte telomere length and cerebral small vessel disease risk in a Chinese Han population: a mendelian randomization analysis

BACKGROUND

Previous observational studies have highlighted potential relationships between the telomerase reverse transcriptase (TERT) gene, short leukocyte telomere length (LTL), and cerebrovascular disease. However, it remains to be established as to whether TERT gene variants are associated with an elevated risk of cerebral small vessel disease (CSVD), and whether there is a causal relationship between LTL and CSVD.

METHODS

Five TERT single nucleotide polymorphisms (SNPs) were analyzed in 307 CSVD patients and 320 healthy controls in whom LTL values were quantified. Allele models and four genetic models were used to explore the relationship between these SNP genotypes and CSVD risk. A Mendelian randomization analysis of CSVD risk was then performed using LTL-related SNPs and the polygenic risk score (PRS) constructed from these SNPs as genetic instrumental variables to predict the causal relationship between LTL and CSVD risk.

RESULTS

Model association analyses identified two SNPs that were significantly associated with CSVD risk. LTL was significantly correlated with age (P < 0.001), and the MR analysis revealed an association between short LTL and an elevated risk of CSVD. PRS-based genetic prediction of short LTLs was also significantly related to an elevated CSVD risk.

CONCLUSION

Multiple genetic models and MR results indicate that TERT gene SNPs may be related to an elevated risk of CSVD, and that shorter LTL may be causally linked to such CSVD risk.

RIOK2 transcriptionally regulates TRiC and dyskerin complexes to prevent telomere shortening

Telomere shortening is a prominent hallmark of aging and is emerging as a characteristic feature of Myelodysplastic Syndromes (MDS) and Idiopathic Pulmonary Fibrosis (IPF). Optimal telomerase activity prevents progressive shortening of telomeres that triggers DNA damage responses. However, the upstream regulation of telomerase holoenzyme components remains poorly defined. Here, we identify RIOK2, a master regulator of human blood cell development, as a critical transcription factor for telomere maintenance. Mechanistically, loss of RIOK2 or its DNA-binding/transactivation properties downregulates mRNA expression of both TRiC and dyskerin complex subunits that impairs telomerase activity, thereby causing telomere shortening. We further show that RIOK2 expression is diminished in aged individuals and IPF patients, and it strongly correlates with shortened telomeres in MDS patient-derived bone marrow cells. Importantly, ectopic expression of RIOK2 alleviates telomere shortening in IPF patient-derived primary lung fibroblasts. Hence, increasing RIOK2 levels prevents telomere shortening, thus offering therapeutic strategies for telomere biology disorders.

Association of Telomere Length in T Lymphocytes, B Lymphocytes, NK Cells and Monocytes with Different Forms of Age-Related Macular Degeneration

BACKGROUND

Age plays a primary role in the development of age-related macular degeneration (AMD). Telomere length (TL) is one of the most relevant biomarkers of aging. In our study, we aimed to determine the association of TL with T lymphocytes, B lymphocytes, NK cells or monocytes with different forms of AMD.

METHODS

Our study included 62 patients with AMD: geographic atrophy (GA), neovascular AMD (NVAMD) with and without macular atrophy and 22 healthy controls. Each leukocyte subtype was isolated from peripheral blood by immunomagnetic separation, and the DNA was purified. The TL in the genomic DNA was determined using qPCR by amplifying the telomere region with specific oligonucleotide primers and normalizing to the control gene. Statistical analysis was performed using R version 4.5.1.

RESULTS

We observed a statistically significant increase in TL in the T cells between the control and NVAMD groups but not for the GA group. The B cells and monocytes showed a significant decrease in TL in all AMD groups. The TL in the NK cells did not decrease in any of the AMD groups.

CONCLUSIONS

The TL in the monocytes had the strongest association with AMD. It reflects a person's "telomeric status" and may become a diagnostic hallmark of these degenerative processes.

Causal Relationship between Aging and Anorexia Nervosa: A White-Matter-Microstructure-Mediated Mendelian Randomization Analysis

This study employed a two-step Mendelian randomization analysis to explore the causal relationship between telomere length, as a marker of aging, and anorexia nervosa and to evaluate the mediating role of changes in the white matter microstructure across different brain regions. We selected genetic variants associated with 675 diffusion magnetic resonance imaging phenotypes representing changes in brain white matter. F-statistics confirmed the validity of the instruments, ensuring robust causal inference. Sensitivity analyses, including heterogeneity tests, horizontal pleiotropy tests, and leave-one-out tests, validated the results. The results show that telomere length is significantly negatively correlated with anorexia nervosa in a unidirectional manner (p = 0.017). Additionally, changes in specific white matter structures, such as the internal capsule, corona radiata, posterior thalamic radiation, left cingulate gyrus, left longitudinal fasciculus, and left forceps minor (p < 0.05), were identified as mediators. These findings enhance our understanding of the neural mechanisms, underlying the exacerbation of anorexia nervosa with aging; emphasize the role of brain functional networks in disease progression; and provide potential biological targets for future therapeutic interventions.

Small Molecules Blocking the Assembly of TCAB1 and Telomerase Complexes: Lead Discovery and Biological Activity

The vast majority of tumor cells maintain the length of the telomeres through a telomerase-dependent maintenance mechanism, allowing for unlimited proliferation. TCAB1 is indispensable for the correct assembly of telomerase complexes and the delivery of telomerase to the telomere. Therefore, this study aimed to explore small molecules capable of interfering with the assembly of TCAB1 and the telomerase complex as novel efficient telomerase inhibitors. Through virtual screening, biological evaluation, and the confirmation of target engagement, the potential ligands of TCAB1 effectively inhibiting telomerase activity were discovered. Among them, compound 9 exhibited telomerase inhibitory activity at a two-digit nanomolar level (IC50 = 0.03 μM), which was dramatically enhanced in comparison with the previously reported telomerase inhibitors. This research, based on the blockage of telomerase assembly through disturbing TCAB1, provides a novel strategy and a potential target for telomerase inhibitor discovery.

Telomeres and SIRT1 as Biomarkers of Gamete Oxidative Stress, Fertility, and Potential IVF Outcome

The number of infertile couples undergoing in vitro fertilisation (IVF) has increased significantly. The efficacy of this procedure is contingent upon a multitude of factors, including gamete quality. One factor influencing gamete quality is oxidative stress, which leads to telomere damage and accelerates cellular ageing. Identifying new biomarkers that can predict the success of assisted reproduction techniques is a current relevant area of research. In this review, we discuss the potential role of SIRT1, a protein known to protect against oxidative stress and telomeres, which are responsible for genome stability, as biomarkers of gamete quality and assisted reproduction technique outcomes.

Dynamic Expansions and Retinal Expression of Spectrally Distinct Short-Wavelength Opsin Genes in Sea Snakes

The photopigment-encoding visual opsin genes that mediate color perception show great variation in copy number and adaptive function across vertebrates. An open question is how this variation has been shaped by the interaction of lineage-specific structural genomic architecture and ecological selection pressures. We contribute to this issue by investigating the expansion dynamics and expression of the duplicated Short-Wavelength-Sensitive-1 opsin (SWS1) in sea snakes (Elapidae). We generated one new genome, 45 resequencing datasets, 10 retinal transcriptomes, and 81 SWS1 exon sequences for sea snakes, and analyzed these alongside 16 existing genomes for sea snakes and their terrestrial relatives. Our analyses revealed multiple independent transitions in SWS1 copy number in the marine Hydrophis clade, with at least three lineages having multiple intact SWS1 genes: the previously studied Hydrophis cyanocinctus and at least two close relatives of this species; Hydrophis atriceps and Hydrophis fasciatus; and an individual Hydrophis curtus. In each lineage, gene copy divergence at a key spectral tuning site resulted in distinct UV and Violet/Blue-sensitive SWS1 subtypes. Both spectral variants were simultaneously expressed in the retinae of H. cyanocinctus and H. atriceps, providing the first evidence that these SWS1 expansions confer novel phenotypes. Finally, chromosome annotation for nine species revealed shared structural features in proximity to SWS1 regardless of copy number. If these features are associated with SWS1 duplication, expanded opsin complements could be more common in snakes than is currently recognized. Alternatively, selection pressures specific to aquatic environments could favor improved chromatic distinction in just some lineages.

Functionalizing tetrahedral framework nucleic acids-based nanostructures for tumor in situ imaging and treatment

Timely in situ imaging and effective treatment are efficient strategies in improving the therapeutic effect and survival rate of tumor patients. In recent years, there has been rapid progress in the development of DNA nanomaterials for tumor in situ imaging and treatment, due to their unsurpassed structural stability, excellent material editability, excellent biocompatibility and individual endocytic pathway. Tetrahedral framework nucleic acids (tFNAs), are a typical example of DNA nanostructures demonstrating superior stability, biocompatibility, cell-entry performance, and flexible drug-loading ability. tFNAs have been shown to be effective in achieving timely tumor in situ imaging and precise treatment. Therefore, the progress in the fabrication, characterization, modification and cellular internalization pathway of tFNAs-based functional systems and their potential in tumor in situ imaging and treatment applications were systematically reviewed in this article. In addition, challenges and future prospects of tFNAs in tumor in situ imaging and treatment as well as potential clinical applications were discussed.

Deciphering the aging process through single-cell cytometric technologies

The advent of single-cell cytometric technologies, in conjunction with advances in single-cell biology, has significantly propelled forward the field of geroscience, enhancing our comprehension of the mechanisms underlying age-related diseases. Given that aging is a primary risk factor for numerous chronic health conditions, investigating the dynamic changes within the physiological landscape at the granularity of single cells is crucial for elucidating the molecular foundations of biological aging. Utilizing hallmarks of aging as a conceptual framework, we review current literature to delineate the progression of single-cell cytometric techniques and their pivotal applications in the exploration of molecular alterations associated with aging. We next discuss recent advancements in single-cell cytometry in terms of the development in instrument, software, and reagents, highlighting its promising and critical role in driving future breakthrough discoveries in aging research.

A Phenotypic Approach to the Discovery of Potent G-Quadruplex Targeted Drugs

G-quadruplex (G4) sequences, which can fold into higher-order G4 structures, are abundant in the human genome and are over-represented in the promoter regions of many genes involved in human cancer initiation, progression, and metastasis. They are plausible targets for G4-binding small molecules, which would, in the case of promoter G4s, result in the transcriptional downregulation of these genes. However, structural information is currently available on only a very small number of G4s and their ligand complexes. This limitation, coupled with the currently restricted information on the G4-containing genes involved in most complex human cancers, has led to the development of a phenotypic-led approach to G4 ligand drug discovery. This approach was illustrated by the discovery of several generations of tri- and tetra-substituted naphthalene diimide (ND) ligands that were found to show potent growth inhibition in pancreatic cancer cell lines and are active in in vivo models for this hard-to-treat disease. The cycles of discovery have culminated in a highly potent tetra-substituted ND derivative, QN-302, which is currently being evaluated in a Phase 1 clinical trial. The major genes whose expression has been down-regulated by QN-302 are presented here: all contain G4 propensity and have been found to be up-regulated in human pancreatic cancer. Some of these genes are also upregulated in other human cancers, supporting the hypothesis that QN-302 is a pan-G4 drug of potential utility beyond pancreatic cancer.

Establishment and Characterization of a Chicken Myoblast Cell Line

Skeletal muscle, which is predominantly constituted by multinucleated muscle fibers, plays a pivotal role in sustaining bodily movements and energy metabolism. Myoblasts, which serve as precursor cells for differentiation and fusion into muscle fibers, are of critical importance in the exploration of the functional genes associated with embryonic muscle development. However, the in vitro proliferation of primary myoblasts is inherently constrained. In this study, we achieved a significant breakthrough by successfully establishing a chicken myoblast cell line through the introduction of the exogenous chicken telomerase reverse transcriptase (chTERT) gene, followed by rigorous G418-mediated pressure screening. This newly developed cell line, which was designated as chTERT-myoblasts, closely resembled primary myoblasts in terms of morphology and exhibited remarkable stability in culture for at least 20 generations of population doublings without undergoing malignant transformation. In addition, we conducted an exhaustive analysis that encompassed cellular proliferation, differentiation, and transfection characteristics. Our findings revealed that the chTERT-myoblasts had the ability to proliferate, differentiate, and transfect after multiple rounds of population doublings. This achievement not only furnished a valuable source of homogeneous avian cell material for investigating embryonic muscle development, but also provided valuable insights and methodologies for establishing primary cell lines.

LKB1 inhibits telomerase activity resulting in cellular senescence through histone lactylation in lung adenocarcinoma

Despite the confirmed role of LKB1 in suppressing lung cancer progression, its precise effect on cellular senescence is unknown. The aim of this research was to clarify the role and mechanism of LKB1 in restraining telomerase activity in lung adenocarcinoma. The results showed that LKB1 induced cellular senescence and apoptosis either in vitro or in vivo. Overexpression of LKB1 in LKB1-deficient A549 cells led to the inhibition of telomerase activity and the induction of telomere dysfunction by regulating telomerase reverse transcriptase (TERT) expression in terms of transcription. As a transcription factor, Sp1 mediated TERT inhibition after LKB1 overexpression. LKB1 induced lactate production and inhibited histone H4 (Lys8) and H4 (Lys16) lactylation, which further altered Sp1-related transcriptional activity. The telomerase inhibitor BIBR1532 was beneficial for achieving the optimum curative effect of traditional chemotherapeutic drugs accompanied by the glycolysis inhibitor 2DG. These data reveal a new mechanism by which LKB1 regulates telomerase activity through lactylation-dependent transcriptional inhibition, and therefore, provide new insights into the effects of LKB1-mediated senescence in lung adenocarcinoma. Our research has opened up new possibilities for the creation of new cancer treatments.

TRF1 and TRF2: pioneering targets in telomere-based cancer therapy

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.

Impact of khat (Catha edulis) and oral contraceptive use on telomerase levels and tumor suppressor genes p53 and p21 in normal subjects and breast cancer patients

This study aimed to evaluate the effects of oral contraceptive (OC) use, khat chewing, and their combined effect on telomerase level and tumor suppressor genes, p53 and p21 in breast cancer (BC) patients and normal volunteers. 140 Yemeni women aged 25-40 years old enrolled, 60 newly diagnosed pretreated BC patients, and 80 control subjects. Venous blood (5 ml) was collected and the results showed BC patients to have significantly raised levels of telomerase, p53, and p21 compared to the control group. The use of OCs significantly raised telomerase in control group with no effect in BC patients; whereas p53 and p21 were significantly increased in BC patients. On the other hand, khat chewing significantly increased p53 in controls and BC patients, whereas p21 was significantly raised in BC patients. The combined use of OCs and khat chewing significantly increased telomerase and p53 in control group, and significantly increased p53 and p21 in BC patients. Telomerase was shown to be a risk factor (OR 4.4) for BC, and the use of OCs was a high-risk factor for increasing telomerase (OR 27.8) in normal subjects. In contrast, khat chewing was shown to be protective (OR 0.142), and the combined use of OCs and khat chewing decreased the risk factor of telomerase from OR 27.8 to 2.1.

LARP3, LARP7, and MePCE are involved in the early stage of human telomerase RNA biogenesis

Human telomerase assembly is a highly dynamic process. Using biochemical approaches, we find that LARP3 and LARP7/MePCE are involved in the early stage of human telomerase RNA (hTR) and that their binding to RNA is destabilized when the mature form is produced. LARP3 plays a negative role in preventing the processing of the 3'-extended long (exL) form and the binding of LARP7 and MePCE. Interestingly, the tertiary structure of the exL form prevents LARP3 binding and facilitates hTR biogenesis. Furthermore, low levels of LARP3 promote hTR maturation, increase telomerase activity, and elongate telomeres. LARP7 and MePCE depletion inhibits the conversion of the 3'-extended short (exS) form into mature hTR and the cytoplasmic accumulation of hTR, resulting in telomere shortening. Taken together our data suggest that LARP3 and LARP7/MePCE mediate the processing of hTR precursors and regulate the production of functional telomerase.