The circadian syndrome predicts cardiovascular disease better than metabolic syndrome in Chinese adults.

BACKGROUND: To compare the predictive value of the circadian syndrome (CircS) and Metabolic syndrome (MetS) for cardiovascular disease. METHOD: We used the data of 9360 Chinese adults aged ≥40 years from the 2011 China Health and Retirement Longitudinal Study (CHARLS). Of the participants, 8253 people were followed in the 2015 survey. MetS was defined using the harmonized criteria. CircS was based on the components of the International Diabetes Federation (IDF) MetS plus short sleep and depression. The cut-off for CircS was set as ≥4. Multivariable logistic regression analysis was used to examine the associations. RESULTS: The prevalence of CircS and MetS was 39.0% and 44.7%. Both MetS and CircS were directly associated with prevalent CVD. The odds ratios for prevalent CVD comparing CircS with MetS, respectively, were 2.83 (95%CI 2.33-3.43) and 2.34 (1.93-2.83) in men, and 2.33 (1.98-2.73) and 1.79 (1.53-2.10) in women. Similar associations were found for incident CVD. The five-year incidence of CVD was 15.1% in CircS and 14.0% in MetS. The number of CircS components has a better predictive power for both prevalent and incident CVD than those of Mets components as indicated by the area under the ROC (AUC). AUC values for CVD in 2011 were higher for CircS than MetS in both men (0.659 (95%CI 0.634-0.684) vs 0.635 (95%CI 0.610-0.661)) and women (0.652 (95%CI 0.632-0.672) vs 0.619 (95%CI 0.599-0.640)). CONCLUSION: The circadian syndrome is a strong and better predictor for CVD than the metabolic syndrome in Chinese adults.

The efficacy of microlearning in improving self-care capability: a systematic review of the literature.

OBJECTIVE: To determine the effectiveness of microlearning in improving an individual's capability for self-care. STUDY DESIGN: Systematic review of the literature. BACKGROUND: The routine adoption of health seeking self-care behaviours can prevent or delay the appearance of various lifestyle diseases including type 2 diabetes and cardiovascular disease. Microlearning delivers complex knowledge in fragments or bite-size 'nuggets' of information and has been applied as a novel intervention to improve individual's self-care capabilities. The aim of this research was to systematically review the literature to determine the effectiveness of microlearning in improving individual self-care capability. METHODS: A search was conducted on 15 July 2019 across five electronic bibliographic databases: EMBASE, MEDLINE, PsycINFO, CINAHL and Scopus. Randomised and non-randomised controlled trials, controlled before-after studies and interrupted time series studies, published between 1 January 1990 and 15 July 2019 and looking at individuals of all ages were included in the search. The search strategy included a keyword search and a string of "(modality) AND (learning) AND (micro)", which broadly described microlearning to cover all available articles that have used microformat learning interventions. The search was combined with keywords and Medical Subject Headings (MeSH) terms for self-care to identify studies of interests. Studies were screened by two reviewers independently and reported using a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart. Data from included articles were extracted using Cochran Data Collection Form. Risk of bias was assessed using Version 2 of the Cochrane Risk-of-bias or Risk Of Bias In Non-Randomised Studies of Interventions (ROBINS-I). RESULTS: 1310 articles were identified in the initial search. A total of 26 manuscripts were included in the narrative synthesis after title and abstract and full text screening was performed by two reviewers. Outcomes of studies were categorised. A total of 23 studies measured cognitive level self-care capabilities-related changes, and 91% showed statistically significant improvements. Only 11 studies measured actual self-care behaviour changes, from which only 36% showed statistically significant results. From the 26 manuscripts included, 25 articles were evaluated as having moderate-to-high risk of bias. CONCLUSION: Under certain conditions, or when combined with monitoring such as tracking daily medicine intake, microlearning can be effective in improving actual self-care behaviours. Microlearning can also positively influence individuals' cognitive self-care capabilities but was largely ineffective in triggering actual self-care behaviour change. More studies are needed to investigate the effectiveness of microlearning in improving self-care capabilities amongst the general population at scale.

The Circadian Syndrome: is the Metabolic Syndrome and much more!

The Metabolic Syndrome is a cluster of cardio-metabolic risk factors and comorbidities conveying high risk of both cardiovascular disease and type 2 diabetes. It is responsible for huge socio-economic costs with its resulting morbidity and mortality in most countries. The underlying aetiology of this clustering has been the subject of much debate. More recently, significant interest has focussed on the involvement of the circadian system, a major regulator of almost every aspect of human health and metabolism. The Circadian Syndrome has now been implicated in several chronic diseases including type 2 diabetes and cardiovascular disease. There is now increasing evidence connecting disturbances in circadian rhythm with not only the key components of the Metabolic Syndrome but also its main comorbidities including sleep disturbances, depression, steatohepatitis and cognitive dysfunction. Based on this, we now propose that circadian disruption may be an important underlying aetiological factor for the Metabolic Syndrome and we suggest that it be renamed the 'Circadian Syndrome'. With the increased recognition of the 'Circadian Syndrome', circadian medicine, through the timing of exercise, light exposure, food consumption, dispensing of medications and sleep, is likely to play a much greater role in the maintenance of both individual and population health in the future.

DNA methylation regulates hypothalamic gene expression linking parental diet during pregnancy to the offspring's risk of obesity in Psammomys obesus.

BACKGROUND/OBJECTIVE: The rising incidence of obesity is a major public health issue worldwide. Recent human and animal studies suggest that parental diet can influence fetal development and is implicated with risk of obesity and type 2 diabetes in offspring. The hypothalamus is central to body energy homoeostasis and appetite by controlling endocrine signals. We hypothesise that offspring susceptibility to obesity is programmed in the hypothalamus in utero and mediated by changes to DNA methylation, which persist to adulthood. We investigated hypothalamic genome-wide DNA methylation in Psammomys obesus diet during pregnancy to the offspring's risk of obesity. METHODS: Using methyl-CpG binding domain capture and deep sequencing (MBD-seq), we examined the hypothalamus of offspring exposed to a low-fat diet and standard chow diet during the gestation and lactation period. RESULTS: Offspring exposed to a low-fat parental diet were more obese and had increased circulating insulin and glucose levels. Methylome profiling identified 1447 genomic regions of differential methylation between offspring of parents fed a low-fat diet compared with parents on standard chow diet. Pathway analysis shows novel DNA methylation changes of hypothalamic genes associated with neurological function, nutrient sensing, appetite and energy balance. Differential DNA methylation corresponded to changes in hypothalamic gene expression of Tas1r1 and Abcc8 in the offspring exposed to low-fat parental diet. CONCLUSION: Subject to parental low-fat diet, we observe DNA methylation changes of genes associated with obesity in offspring.

Epigenetic changes in diabetes.

Diabetes is a multifactorial disease with numerous pathways influencing its progression and recent observations suggest that the complexity of the disease cannot be entirely accounted for by genetic predisposition. A compelling argument for an epigenetic component is rapidly emerging. Epigenetic processes at the chromatin template significantly sensitize transcriptional and phenotypic outcomes to environmental signaling information including metabolic state, nutritional requirements and history. Epigenetic mechanisms impact gene expression that could predispose individuals to the diabetic phenotype during intrauterine and early postnatal development, as well as throughout adult life. Furthermore, epigenetic changes could account for the accelerated rates of chronic and persistent microvascular and macrovascular complications associated with diabetes. Epidemiological and experimental animal studies identified poor glycemic control as a major contributor to the development of diabetic complications and highlight the requirement for early intervention. Early exposure to hyperglycemia can drive the development of complications that manifest late in the progression of the disease and persist despite improved glycemic control, indicating a memory of the metabolic insult. Understanding the molecular events that underlie these transcriptional changes will significantly contribute to novel therapeutic interventions to prevent, reverse or retard the deleterious effects of the diabetic milieu.

Yap regulates skeletal muscle fatty acid oxidation and adiposity in metabolic disease.

Obesity is a major risk factor underlying the development of metabolic disease and a growing public health concern globally. Strategies to promote skeletal muscle metabolism can be effective to limit the progression of metabolic disease. Here, we demonstrate that the levels of the Hippo pathway transcriptional co-activator YAP are decreased in muscle biopsies from obese, insulin-resistant humans and mice. Targeted disruption of Yap in adult skeletal muscle resulted in incomplete oxidation of fatty acids and lipotoxicity. Integrated 'omics analysis from isolated adult muscle nuclei revealed that Yap regulates a transcriptional profile associated with metabolic substrate utilisation. In line with these findings, increasing Yap abundance in the striated muscle of obese (db/db) mice enhanced energy expenditure and attenuated adiposity. Our results demonstrate a vital role for Yap as a mediator of skeletal muscle metabolism. Strategies to enhance Yap activity in skeletal muscle warrant consideration as part of comprehensive approaches to treat metabolic disease.

Disparity of histone deacetylase inhibition on repair of radiation-induced DNA damage on euchromatin and constitutive heterochromatin compartments.

Epigenetic regulation of chromatin structure is central to the process of DNA repair. A well-characterized epigenetic feature is the dynamic phosphorylation of the histone H2AX (gammaH2AX) and mobilization of double strand break (DSB) recognition and repair factors to the site. How chromatin structure is altered in response to DNA damage and how such alterations influence DSB repair mechanisms are currently relevant issues. Despite the clear link between histone deacetylases (HDACs) and radiosensitivity, how histone hyperacetylation influence DSB repair remains poorly understood. We have determined the structure of chromatin is a major factor determining radiosensitivity and repair in human cells. Trichostatin A (TSA) enhances radiosensitivity with dose modification factors of 1.2 and 1.9 at 0.2 and 1 microM, respectively. Cells treated with TSA causing hyperacetylation and remodelling on euchromatic alleles coexist with gammaH2AX accumulation in radiosensitized cells. Formation of gammaH2AX on heterochromatin was significantly reduced even when cells were treated with TSA, suggesting that chromatin structure and histone hyperacetylation are pronounced features of radiation sensitivity and repair in euchromatic regions.

Will broad-spectrum histone deacetylase inhibitors be superseded by more specific compounds?

Histone deacetylase (HDAC) inhibitors can induce differentiation, cell cycle and growth arrest or in certain cases apoptosis in cancer cells. In a remarkably short period of time, especially considering that their mechanism of action remains largely undefined, HDAC inhibitors have realized both success and failure as therapeutics for cancer in clinical trials. Notably, the pleiotropic HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA) and depsipeptide, have shown efficacy in a wide range of cancers, in particular for cutaneous T-cell lymphoma (CTCL), and are progressing in phase II clinical studies. However, evidence is accumulating that specific HDAC enzymes are important with respect to clinical efficacy, calling the usefulness of the classical inhibitors into question. Class I enzymes are being heralded as the most clinically relevant, however, this is still controversial and much of the information is in the private domain. Nevertheless, the potential to alter the expression of a more focused, disease-related subset of genes and to limit adverse effects has prompted the development of isoform-specific HDAC inhibitors. Here, we consider the growing view that broad-spectrum HDAC inhibitors may be superseded by more specific compounds.

Chromatin modifications and DNA double-strand breaks: the current state of play.

The packaging and compaction of DNA into chromatin is important for all DNA-metabolism processes such as transcription, replication and repair. The involvement of chromatin modifications in transcriptional regulation is relatively well characterized, and the distinct patterns of chromatin transitions that guide the process are thought to be the result of a code on the histone proteins (histone code). In contrast to transcription, the intricate link between chromatin and responses to DNA damage has been given attention only recently. It is now emerging that specific ATP-dependent chromatin remodeling complexes (including the Ino80, Swi/Snf and RSC remodelers) and certain constitutive (methylation of lysine 79 of histone H3) and DNA damage-induced covalent histone modifications (the most well characterized being the rapid phosphorylation of histone H2A) facilitate responses to double-strand breaks. Indeed, evidence is already accumulating for a DNA repair-specific histone code. In this review, the recent advances in our understanding of the relationship between chromatin modifications and double-strand break signaling and repair is discussed.

Modulation of cellular radiation responses by histone deacetylase inhibitors.

Histone deacetylase (HDAC) inhibitors are emerging as a new class of targeted cancer chemotherapeutics. Several HDAC inhibitors are currently in clinical trials and promising anticancer effects at well-tolerated doses have been observed for both hematologic and solid cancers. HDAC inhibitors have been shown to induce cell-cycle and growth arrest, differentiation and in certain cases apoptosis in cell cultures and in vivo. However, it is known that these compounds induce varying responses in different cells and biological settings, and identifying their precise mechanisms of action is an area of great interest. Important findings are continually expanding our understanding of the cellular effects of HDAC inhibitors and recent studies will be briefly outlined in this review. In addition to their intrinsic anticancer properties, numerous studies have demonstrated that HDAC inhibitors can modulate cellular responses to other cytotoxic modalities including ionizing radiation, ultraviolet radiation and chemotherapeutic drugs. Hence, there is a growing interest in potential clinical use of HDAC inhibitors in combination with conventional cancer therapies. In this review, the interaction of HDAC inhibitors with other anticancer agents is discussed. The focus of the article is on the different mechanisms by which HDAC inhibitors enhance the sensitivity of cells to the effects of ionizing radiation.

Altered methylation of the human MDR1 promoter is associated with acquired multidrug resistance.

One of the most important forms of drug resistance in acute myeloid leukemia is the multidrug resistance (MDR) phenotype, which is characterized by the expression of the MDR1 gene product, P-glycoprotein. Although a number of factors affect MDR1 gene expression, the genetic events that "switch on" the human MDR1 gene in tumor cells that were previously P-glycoprotein negative have remained elusive. Here, we report evidence that the methylation status of the human MDR1 promoter may serve as a basis for this "switch." Based on Southern analysis using methylation-sensitive and methylation-insensitive restriction enzymes, a tight correlation was found between MDR phenotype and demethylation of the 5' region of the MDR1 gene in a human T cell leukemia cell line. Similar results were obtained from the analysis of P-glycoprotein-positive and P-glycoprotein-negative samples of chronic lymphocytic leukemia. Treatment of the cell lines with the demethylating agent 5'-azadeoxycytidine altered the methylation pattern of the MDR1 promoter in P-glycoprotein-negative cells to resemble that of P-glycoprotein-positive cells and activated the promoter such that MDR1 mRNA was now detectable. Treatment also resulted in an increased resistance to epirubicin and decreased daunomycin accumulation, both of which were reversible by verapamil, a characteristic of the classical MDR phenotype in cells expressing P-glycoprotein. These results suggest that the MDR phenotype may be acquired as a result of changes in methylation of the MDR1 promoter.

Absolute quantitation of MDR1 transcripts using heterologous DNA standards--validation of the competitive RT-PCR (CRT-PCR) approach.

The multidrug resistance (MDR1) gene product, P-glycoprotein (Pgp), is a 170-kDa ATP-dependent pump that expels a variety of anticancer drugs out of malignant cells, reducing drug accumulation and thus antitumor activity. In recent years, considerable data has been presented that indicates the need to standardize detection methods for Pgp and MDR1. Reverse transcription (RT)-PCR is one of the most sensitive and specific techniques used to detect MDR1. Nevertheless, there is the need to address working criteria for quantitation by RT-PCR. In this study, we describe a flexible assay used to quantify MDR1 gene expression using heterologous (nonhomologous) standards for use in competitive RT-PCR (CRT-PCR). Our guidelines were to use a RT-PCR quantitation method that was independent of exponential phase kinetics, sensitive (detect low levels of gene measurement in clinical samples) and did not require radiolabel. Furthermore, the method would need to be flexible enough for the user to express quantitation as either the number of cells or amount of cDNA used in CRT-PCR. Using low-stringency amplification, heterologous DNA competitors were constructed for MDR1 and as an internal reference, the ubiquitously expressed human histone variant 3.3 (H3.3). The benefits of this approach are threefold: (i) amplification kinetics of target and competitor molecules are identical, (ii) low-stringency PCR is a simple way of constructing heterologous DNA competitors that do not require special storage conditions and (iii) heterologous competitors avoid the formation of heteroduplex molecules. We conclude that CRT-PCR is an extremely flexible and sensitive assay that can quantify MDR1 based on competitive amplification of a heterologous competitor. This might complement future efforts to standardize MDR1 detection methods using RT-PCR.

DNA methylation and histone deacetylation in the control of gene expression: basic biochemistry to human development and disease.

DNA methylation is a major determinant in the epigenetic silencing of genes. The mechanisms underlying the targeting of DNA methylation and the subsequent repression of transcription are relevant to human development and disease, as well as for attempts at somatic gene therapy. The success of transgenic technologies in plants and animals is also compromised by DNA methylation-dependent silencing pathways. Recent biochemical experiments provide a mechanistic foundation for understanding the influence of DNA methylation on transcription. The DNA methyltransferase Dnmt1, and several methyl-CpG binding proteins, MeCP2, MBD2, and MBD3, all associate with histone deacetylase. These observations firmly connect DNA methylation with chromatin modifications. They also provide new pathways for the potential targeting of DNA methylation to repressive chromatin as well as the assembly of repressive chromatin on methylated DNA. Here we discuss the implications of the methylation-acetylation connection for human cancers and the developmental syndromes Fragile X and Rett, which involve a mistargeting of DNA methylation-dependent repression.

Immunomodulatory effects of histone deacetylase inhibitors.

Histone deacetylase inhibitors (HDACi) have emerged as a new generation of anticancer therapeutics. The classical broad-spectrum HDACi typically alter the cell cycle distribution and induce cell death, apoptosis and differentiation in malignant and transformed cells. This provides the basis for the clinical potential of HDACi in cancer therapy. Currently two compounds, suberoylanilide hydroxamic acid (SAHA, Vorinostat, Zolinza™) and depsipeptide (Romidepsin, Istodax™) have been approved for by the US Food and Drug Administration for the treatment of refractory cutaneous T-cell lymphoma. Apart from clinical application in oncology, HDACi have also been investigated as potential therapeutics for various pathologies including those of the central nervous system (such as Huntington's disease and multiple sclerosis), cardiac conditions (particularly hypertrophy), arthritis and malaria. Further, evidence is accumulating for potent immunomodulatory effects of classical HDACi which is the focus of this review. We review the antiinflammatory effects of HDACi and in particular findings implicating regulation of the innate and adaptive immune systems by HDAC enzymes. The recent findings highlighting the immunomodulatory function of HDAC11 which relates to balancing immune activation versus tolerance are also discussed.

Epigenetic and genetic mechanisms of abnormal 11p15 genomic imprinting in Silver-Russell and Beckwith-Wiedemann syndromes.

Fetal growth is a complex process depending on the genetics of the fetus, the availability of nutrients to the fetus, maternal nutrition and various growth factors and hormones of maternal, fetal and placental origin. The IGF system, and more particularly IGF2, is one of the most important endocrine and paracrine growth systems regulating fetal and placental growth (reviewed in [1]). The IGF2 gene is regulated by genomic imprinting and is expressed only from the paternally-inherited allele in most tissues during fetal development and after birth. Imprinted genes are tightly regulated and are therefore particularly susceptible to changes, including environmental and nutritional changes. Dysregulation of a cluster of imprinted genes, including the IGF2 gene within the 11p15 region, results in two fetal growth disorders (Silver-Russell and Beckwith-Wiedemann syndromes) with opposite growth phenotypes. Those two syndromes are model imprinting disorders to decipher the regulation of genomic imprinting.

gammaH2AX: a sensitive molecular marker of DNA damage and repair.

Phosphorylation of the Ser-139 residue of the histone variant H2AX, forming gammaH2AX, is an early cellular response to the induction of DNA double-strand breaks. Detection of this phosphorylation event has emerged as a highly specific and sensitive molecular marker for monitoring DNA damage initiation and resolution. Further, analysis of gammaH2AX foci has numerous other applications including, but not limited to, cancer and aging research. Quantitation of gammaH2AX foci has also been applied as a useful tool for the evaluation of the efficacy of various developmental drugs, particularly, radiation modifying compounds. This review focuses on the current status of gammaH2AX as a marker of DNA damage and repair in the context of ionizing radiation. Although the emphasis is on gamma-radiation-induced gammaH2AX foci, the effects of other genotoxic insults including exposure to ultraviolet rays, oxidative stress and chemical agents are also discussed.

Coordination of epigenetic events.

During the course of DNA damage a complex repertoire of molecular signals, chromatin determinants and specific transcription factors are set in motion for repair. In many instances, the response pathway can be characterized by profound changes in molecular remodeling and is intimately linked with DNA replication and gene transcription. Our understanding of the molecular pathways has come from scientific developments that represent many disparate disciplines, such as cancer (epi)genetics, chromatin modifications during cellular development and the emerging prominence of epigenetic events in human disease. These multidisciplinary areas reveal a functional relationship and suggest that repair and transcription must coincide in the context of chromatin. We have come to appreciate the repair process and the role of transcriptional components in a sophisticated program of epigenetic regulation, and we have learnt much since the first description of the nucleosome as a spheroid disklike unit. The coordinated and ordered response to DNA damage can specify structures that mobilize and remodel nucleosomes. Investigators will undoubtedly continue to explore the structural and functional states of DNA damage repair and continue to profile the sequence of events and scrutinize the molecular signatures that specify these changes in chromatin dynamics, genomic stability and transcriptional performance. In this special issue, authors have contributed reviews that discuss hypotheses and results regarding DNA damage repair and transcription. The topics covered range from DNA repair in a chromatin environment to the deadly double-strand break, histone modifications to ATP-dependent chromatin remodeling, gene silencing in cancer to apoptosis and regulation of chromatin dynamics by DNA methylation. The scene is set for a new view of damage detection and repair by the coordination of epigenetic states.

Double-strand breaks: signaling pathways and repair mechanisms.

Double-strand breaks arise frequently in the course of endogenous - normal and pathological - cellular DNA metabolism or can result from exogenous agents such as ionizing radiation. It is generally accepted that these lesions represent one of the most severe types of DNA damage with respect to preservation of genomic integrity. Therefore, cells have evolved complex mechanisms that include cell-cycle arrest, activation of various genes, including those associated with DNA repair, and in certain cases induction of the apoptotic pathway to respond to double-strand breaks. In this review we discuss recent progress in our understanding of cellular responses to DNA double-strand breaks. In addition to an analysis of the current paradigms of detection, signaling and repair, insights into the significance of chromatin remodeling in the double-strand break-response pathways are provided.

Analysis of chromatin-immunopurified MeCP2-associated fragments.

As molecular biologists, we are continuing to unravel the interactions by which DNA binding proteins mediate the expression of genes. The chromatin immunoprecipitation (ChIP) technique provides us with an exquisite tool to investigate the interplay between chromatin structure and its role in regulating transcription, replication, and recombination in vivo. We describe a robust assay used to identify the molecular determinants associated with chromatin. In this article we illustrate the ChIP technique and use the transcriptionally silent-hypermethylated multidrug resistance (MDR1) gene as the platform for methyl-CpG binding protein 2 (MeCP2) localization on chromatin. Driven by the hypothesis that repression is strongly dependent on the methylation profile of the endogenous promoter, we demonstrate that MDR1 is targeted by MeCP2. Methylated MDR1 chromatin is highly enriched with MeCP2 and is in striking contrast to localization observed in cells in which MDR1 is transcriptionally active. In a distinct model system we discuss experimental methods used to immunopurify the MeCP2 repressor complex on chromatin and quantify protein-DNA association by competitive PCR approach.