RESUMEN
Telomeres are nucleoprotein structures at the ends of linear chromosomes. In humans, they consist of TTAGGG repeats, which are bound by dedicated proteins such as the shelterin complex. This complex blocks unwanted DNA damage repair at telomeres, e.g. by suppressing nonhomologous end joining (NHEJ) through its subunit TRF2. Here, we describe ZNF524, a zinc finger protein that directly binds telomeric repeats with nanomolar affinity, and reveal base-specific sequence recognition by cocrystallization with telomeric DNA. ZNF524 localizes to telomeres and specifically maintains the presence of the TRF2/RAP1 subcomplex at telomeres without affecting other shelterin members. Loss of ZNF524 concomitantly results in an increase in DNA damage signaling and recombination events. Overall, ZNF524 is a direct telomere-binding protein involved in the maintenance of telomere integrity.
Asunto(s)
Telómero , Proteína 2 de Unión a Repeticiones Teloméricas , Humanos , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Telómero/genética , Telómero/metabolismo , Complejo Shelterina , Proteínas de Unión a Telómeros/metabolismo , ADN/genética , ADN/metabolismoRESUMEN
BACKGROUND: With an aging population, developing non-pharmacological interventions (NPIs) to delay dementia has become critical. Apart from cognitive decline, dementia is associated with multiple pathophysiology, including increased oxidative stress, dysregulated gene expressions, cytokine, neurotrophin, and stress markers, telomere shortening, and deteriorations in brain connectivity. Although mindfulness practices have been proposed to ameliorate these biological changes, no empirical studies were conducted. We thus aimed to investigate the effects of mindfulness awareness practice (MAP) to prevent cognitive decline and improve peripheral biomarkers in community-dwelling older adults diagnosed with mild cognitive impairment (MCI). METHODS/DESIGN: This was a single-blinded and parallel-group randomized controlled trial with two arms (intervention and active control arms), conducted over nine months. A total of 60 consenting community-dwelling older adults diagnosed with MCI were planned to be randomized in a 1:1 ratio to either the MAP or the Health Education Program (HEP). Interventions were performed weekly for the initial 12 weeks, and monthly for the subsequent six months. Outcome measures were assessed at baseline, 3-month, and 9-month post-intervention by blinded assessors. Primary outcomes were neurocognitive tests, comprehensive peripheral biomarkers, and brain imaging scans. Secondary outcomes included basic health screening measures, affective symptoms, and measures of physical functions. Linear-mixed models were used to examine the effects of MAP on these outcome measures. SIGNIFICANCE: This is the first randomized controlled trial to systematically investigate the effects of a mindfulness intervention in improving cognitive functions and various biomarkers in community-dwelling older adults diagnosed with MCI. Our findings have the potential to inform mindfulness intervention as a novel approach to delay dementia.
Asunto(s)
Disfunción Cognitiva , Demencia , Atención Plena , Anciano , Cognición , Disfunción Cognitiva/prevención & control , Demencia/prevención & control , Humanos , Pruebas de Estado Mental y Demencia , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
There is ample scientific and clinical evidence of the effects of gut microbiota on the brain but no definitive evidence that the brain can affect changes in gut microbiota under the bi-directional gut-brain axis concept. As there is no pharmacotherapeutic intervention for the early stages of cognitive decline, research has focused on cognitive stimulation in reversing or slowing the impairment. Elderly patients diagnosed with mild cognitive impairment underwent a randomized-control trial of mindful awareness practice. Neuropsychological assessments, inflammatory markers, and gut microbiota profiles were tested. Here, we report that their cognitive impairment was improved and associated with changes in gut bacterial profile. A cognition-score-dependent-abundance was observed in Ruminococcus vs Recognition Trials (RT), Digit Span Backward (DSB), Semantic Fluency Span (SFS) and Memory Domain (MD); Coprococcus vs DSB, Color Trails Test 2 (CTT2) and Block Design (BD); Parabacteroides vs DSB and SFS; Fusobacterium vs DSB and CTT2; Enterobacteriaceae vs BD and SFS; Ruminococcaceae vs DSB; Phascolarctobacterium vs MD. The study showed for the first-time, alteration in the cognitive capacity leading to the corresponding changes in microbiota profiles. This strongly suggests that signals from the different segments of brain could dictate directly or indirectly the abundances of specific gut microbes.
Asunto(s)
Encéfalo/fisiopatología , Cognición , Disfunción Cognitiva/terapia , Microbioma Gastrointestinal , Intestinos/microbiología , Atención Plena , Factores de Edad , Anciano , Anciano de 80 o más Años , Disfunción Cognitiva/microbiología , Disfunción Cognitiva/fisiopatología , Disfunción Cognitiva/psicología , Heces/microbiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Singapur , Factores de Tiempo , Resultado del TratamientoRESUMEN
Telomeres are nucleoprotein structures at the ends of linear chromosomes and present an essential feature for genome integrity. Vertebrate telomeres usually consist of hexameric TTAGGG repeats, however, in cells that use the alternative lengthening of telomeres (ALT) mechanism, variant repeat sequences are interspersed throughout telomeres. Previously, it was shown that NR2C/F transcription factors bind to TCAGGG variant repeats and contribute to telomere maintenance in ALT cells. While specific binders to other variant repeat sequences have been lacking to date, we here identify ZBTB10 as the first TTGGGG-binding protein and demonstrate direct binding via the two zinc fingers with affinity in the nanomolar range. Concomitantly, ZBTB10 co-localizes with a subset of telomeres in ALT-positive U2OS cells and interacts with TRF2/RAP1 via the N-terminal region of TRF2. Our data establishes ZBTB10 as a novel variant repeat binding protein at ALT telomeres.
Asunto(s)
Proteínas Represoras/genética , Homeostasis del Telómero/genética , Telómero/genética , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Sitios de Unión/genética , Cromosomas/genética , Proteínas de Unión al ADN/genética , Genoma/genética , Humanos , Unión Proteica/genética , Secuencias Repetitivas de Ácidos Nucleicos/genética , Complejo Shelterina , Proteínas de Unión a Telómeros/genéticaRESUMEN
Vitamin E family members: tocotrienols and tocopherols are widely known for their health benefits. Decades of research on tocotrienols have shown they have diverse biological activities such as antioxidant, anti-inflammatory, anticancer, neuroprotective and skin protection benefits, as well as improved cognition, bone health, longevity and reduction of cholesterol levels in plasma. Tocotrienols also modulate several intracellular molecular targets and, most importantly, have been shown to improve lipid profiles, reduce total cholesterol and reduce the volume of white matter lesions in human clinical trials. This review provides a comprehensive update on the little-known therapeutic potentials of tocotrienols, which tocopherols lack in a variety of inflammation-driven diseases.
Asunto(s)
Antioxidantes/uso terapéutico , Tocotrienoles/uso terapéutico , Animales , Antioxidantes/administración & dosificación , Antioxidantes/farmacología , Sistemas de Liberación de Medicamentos , Humanos , Mediadores de Inflamación/inmunología , Neoplasias/tratamiento farmacológico , Transducción de Señal/efectos de los fármacos , Tocoferoles/administración & dosificación , Tocoferoles/uso terapéutico , Tocotrienoles/administración & dosificación , Tocotrienoles/farmacologíaRESUMEN
Telomeres constitute the ends of linear chromosomes and together with the shelterin complex form a structure essential for genome maintenance and stability. In addition to the constitutive binding of the shelterin complex, other direct, yet more transient interactions are mediated by the CST complex and HOT1/HMBOX1, while subtelomeric variant repeats are recognized by NR2C/F transcription factors. Recently, the Kruppel-like zinc finger protein ZBTB48/HKR3/TZAP has been described as a novel telomere-associated factor in the vertebrate lineage. Here, we show that ZBTB48 binds directly both to telomeric and to subtelomeric variant repeat sequences. ZBTB48 is found at telomeres of human cancer cells regardless of the mode of telomere maintenance and it acts as a negative regulator of telomere length. In addition to its telomeric function, we demonstrate through a combination of RNAseq, ChIPseq and expression proteomics experiments that ZBTB48 acts as a transcriptional activator on a small set of target genes, including mitochondrial fission process 1 (MTFP1). This discovery places ZBTB48 at the interface of telomere length regulation, transcriptional control and mitochondrial metabolism.
Asunto(s)
Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica , Telómero/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Activación Transcripcional , Animales , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas de Homeodominio/metabolismo , Humanos , Mitocondrias/metabolismo , Proteómica , Secuencias Repetitivas de Ácidos Nucleicos , Complejo Shelterina , Homeostasis del Telómero/genética , Proteínas de Unión a Telómeros/genética , Proteínas de Unión a Telómeros/metabolismoRESUMEN
Cancer is one of the most studied areas of human biology over the past century. Despite having attracted much attention, hype, and investments, the search to find a cure for cancer remains an uphill battle. Recent discoveries that challenged the central dogma of molecular biology not only further increase the complexity but also demonstrate how various types of noncoding RNAs such as microRNA and long noncoding RNA, as well as their related processes such as RNA editing, are important in regulating gene expression. Parallel to this aspect, an increasing number of reports have focused on a family of proteins known as DEAD/H-box helicases involved in RNA metabolism, regulation of long and short noncoding RNAs, and novel roles as "editing helicases" and their association with cancers. This review summarizes recent findings on the roles of RNA helicases in various cancers, which are broadly classified into adult solid tumors, childhood solid tumors, leukemia, and cancer stem cells. The potential small molecule inhibitors of helicases and their therapeutic value are also discussed. In addition, analyzing next-generation sequencing data obtained from public portals and reviewing existing literature, we provide new insights on the potential of DEAD/H-box helicases to act as pharmacological drug targets in cancers.
Asunto(s)
ARN Helicasas DEAD-box/antagonistas & inhibidores , ARN Helicasas DEAD-box/metabolismo , Inhibidores Enzimáticos/uso terapéutico , Neoplasias/tratamiento farmacológico , Neoplasias/enzimología , ARN Helicasas DEAD-box/genética , Factor 4A Eucariótico de Iniciación/antagonistas & inhibidores , Humanos , Neoplasias/genéticaRESUMEN
Telomeres are the heterochromatic repeat regions at the ends of eukaryotic chromosomes, whose length is considered to be a determinant of biological ageing. Normal ageing itself is associated with telomere shortening. Here, critically short telomeres trigger senescence and eventually cell death. This shortening rate may be further increased by inflammation and oxidative stress and thus affect the ageing process. Apart from shortened or dysfunctional telomeres, cells undergoing senescence are also associated with hyperactivity of the transcription factor NF-κB and overexpression of inflammatory cytokines such as TNF-α, IL-6, and IFN-γ in circulating macrophages. Interestingly, telomerase, a reverse transcriptase that elongates telomeres, is involved in modulating NF-κB activity. Furthermore, inflammation and oxidative stress are implicated as pre-disease mechanisms for chronic diseases of ageing such as neurodegenerative diseases, cardiovascular disease, and cancer. To date, inflammation and telomere shortening have mostly been studied individually in terms of ageing and the associated disease phenotype. However, the interdependent nature of the two demands a more synergistic approach in understanding the ageing process itself and for developing new therapeutic approaches. In this review, we aim to summarize the intricate association between the various inflammatory molecules and telomeres that together contribute to the ageing process and related diseases.
Asunto(s)
Envejecimiento/genética , Envejecimiento/patología , Inflamación/genética , Inflamación/patología , Telómero/patología , Animales , Humanos , Telómero/metabolismoRESUMEN
Despite significant advances in treatment modalities over the last decade, neither the incidence of the disease nor the mortality due to cancer has altered in the last thirty years. Available anti-cancer drugs exhibit limited efficacy, associated with severe side effects, and are also expensive. Thus identification of pharmacological agents that do not have these disadvantages is required. Curcumin, a polyphenolic compound derived from turmeric (Curcumin longa), is one such agent that has been extensively studied over the last three to four decades for its potential anti-inflammatory and/or anti-cancer effects. Curcumin has been found to suppress initiation, progression, and metastasis of a variety of tumors. These anti-cancer effects are predominantly mediated through its negative regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other oncogenic molecules. It also abrogates proliferation of cancer cells by arresting them at different phases of the cell cycle and/or by inducing their apoptosis. The current review focuses on the diverse molecular targets modulated by curcumin that contribute to its efficacy against various human cancers.
Asunto(s)
Antiinflamatorios/uso terapéutico , Antineoplásicos Fitogénicos/uso terapéutico , Proliferación Celular/efectos de los fármacos , Curcumina/uso terapéutico , Neoplasias , Animales , Humanos , Metástasis de la Neoplasia , Neoplasias/metabolismo , Neoplasias/patología , Neoplasias/prevención & controlRESUMEN
RATIONALE: Leukocyte telomere length (LTL) and plasma homocysteine (HCY) have been independently associated with cardiovascular disease (CVD) morbidity and mortality. However, few studies have investigated the association between LTL and HCY levels. OBJECTIVE: This study investigated the association of LTL with CVD risk factors, including HCY, in an overt CVD-free Singapore Chinese population comprised of middle aged and elderly, the age group at risk of developing CVD. APPROACH: The association of plasma HCY and other CVD biomarkers with LTL were assessed in 100 samples drawn from the Singapore Chinese Health Study (SCHS). SCHS, a population-based cohort, recruited Chinese individuals, aged 45-74 years, between 1993 and 1998. Questionnaire data were collected via face-to-face interviews. Known CVD biomarkers were measured from the blood collected at the time of recruitment, and LTL was measured using the conventional Southern blot method. RESULTS: After adjustment for age, gender, smoking status, education, and dialect, LTL was found to be inversely associated with plasma HCY levels (p for trend=0.014). Serum urate showed a weak association (p for trend=0.056). Other CVD risk factors and nutrients, namely total cholesterol, low-density lipoprotein (LDL), triglycerides and creatinine, high-density lipoprotein (HDL), folate, and vitamin B6 showed the expected trend with LTL, but did not reach statistical significance. CONCLUSION: LTL displayed an inverse association with plasma HCY. This LTL-HCY inverse association in subjects lacking obvious cardiovascular events suggests that telomere length may be an intermediary in the biological mechanism by which elevated HCY leads to CVD.
Asunto(s)
Enfermedades Cardiovasculares/epidemiología , Homocisteína/sangre , Leucocitos/metabolismo , Homeostasis del Telómero/genética , Telómero/genética , Anciano , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/genética , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Pronóstico , Factores de Riesgo , Singapur/epidemiologíaRESUMEN
Rapid and accurate diagnosis of viral respiratory infections is crucial for patient management. Multiplex reverse transcriptase polymerase chain reaction (mRT-PCR) is used increasingly to diagnose respiratory infections and has shown to be more sensitive than viral culture and antigen detection. Objective of the present study was to develop a one-step mRT-PCR that could detect 18 respiratory viruses in three sets. The method was compared with real time RT-PCR (rRT-PCR) for its sensitivity and specificity. Clinical specimens from 843 pediatric patients with respiratory symptoms were used in the study. 503 (59.7%) samples were detected positive by mRT-PCR. Of these 462 (54.8%) exhibited presence of a single pathogen and 41 (4.9%) had multiple pathogens. rRT-PCR detected 439 (52.1%) positive samples, where 419 (49.7%) exhibited one virus and 20 (2.4%) showed co-infections. Concordance between mRT-PCR and rRT-PCR was 91.9% and kappa correlation 0.837. Sensitivity and specificity of mRT-PCR were 99.5% and 83.7% while that of rRT-PCR was 86.9% and 99.4% respectively. Rhinovirus (17.2%) was the most frequently detected virus followed by respiratory syncytial virus B (15.4%), H1N1pdm09 (8.54%), parainfluenza virus-3 (5.8%) and metapneumovirus (5.2%). In conclusion, mRT-PCR is a rapid, cost effective, specific and highly sensitive method for detection of respiratory viruses.