'; ?> geneimprint : Hot off the Press http://www.geneimprint.com/site/hot-off-the-press Daily listing of the most recent articles in epigenetics and imprinting, collected from the PubMed database. en-us Fri, 03 Jul 2015 15:13:21 PDT Fri, 03 Jul 2015 15:13:21 PDT jirtle@radonc.duke.edu james001@jirtle.com The landscape of genomic imprinting across diverse adult human tissues. Baran Y, Subramaniam M, Biton A, Tukiainen T, Tsang EK, Rivas MA, Pirinen M, Gutierrez-Arcelus M, Smith KS, Kukurba KR, Zhang R, Eng C, Torgerson DG, Urbanek C,  , Li JB, Rodriguez-Santana JR, Burchard EG, Seibold MA, MacArthur DG, Montgomery SB, Zaitlen NA, Lappalainen T
Genome Res (Jul 2015)

Genomic imprinting is an important regulatory mechanism that silences one of the parental copies of a gene. To systematically characterize this phenomenon, we analyze tissue specificity of imprinting from allelic expression data in 1582 primary tissue samples from 178 individuals from the Genotype-Tissue Expression (GTEx) project. We characterize imprinting in 42 genes, including both novel and previously identified genes. Tissue specificity of imprinting is widespread, and gender-specific effects are revealed in a small number of genes in muscle with stronger imprinting in males. IGF2 shows maternal expression in the brain instead of the canonical paternal expression elsewhere. Imprinting appears to have only a subtle impact on tissue-specific expression levels, with genes lacking a systematic expression difference between tissues with imprinted and biallelic expression. In summary, our systematic characterization of imprinting in adult tissues highlights variation in imprinting between genes, individuals, and tissues.]]>
Thu, 02 Jul 2015 00:00:00 PDT
i-cisTarget 2015 update: generalized cis-regulatory enrichment analysis in human, mouse and fly. Imrichová H, Hulselmans G, Kalender Atak Z, Potier D, Aerts S
Nucleic Acids Res (Jul 2015)

i-cisTarget is a web tool to predict regulators of a set of genomic regions, such as ChIP-seq peaks or co-regulated/similar enhancers. i-cisTarget can also be used to identify upstream regulators and their target enhancers starting from a set of co-expressed genes. Whereas the original version of i-cisTarget was focused on Drosophila data, the 2015 update also provides support for human and mouse data. i-cisTarget detects transcription factor motifs (position weight matrices) and experimental data tracks (e.g. from ENCODE, Roadmap Epigenomics) that are enriched in the input set of regions. As experimental data tracks we include transcription factor ChIP-seq data, histone modification ChIP-seq data and open chromatin data. The underlying processing method is based on a ranking-and-recovery procedure, allowing accurate determination of enrichment across heterogeneous datasets, while also discriminating direct from indirect target regions through a 'leading edge' analysis. We illustrate i-cisTarget on various Ewing sarcoma datasets to identify EWS-FLI1 targets starting from ChIP-seq, differential ATAC-seq, differential H3K27ac and differential gene expression data. Use of i-cisTarget is free and open to all, and there is no login requirement. Address: http://gbiomed.kuleuven.be/apps/lcb/i-cisTarget.]]>
Thu, 02 Jul 2015 00:00:00 PDT
Living long and ageing well: is epigenomics the missing link between nature and nurture? Rea IM, Dellet M, Mills KI,  
Biogerontology (Jul 2015)

Human longevity is a complex trait and increasingly we understand that both genes and lifestyle interact in the longevity phenotype. Non-genetic factors, including diet, physical activity, health habits, and psychosocial factors contribute approximately 50 % of the variability in human lifespan with another 25 % explained by genetic differences. Family clusters of nonagenarian and centenarian siblings, who show both exceptional age-span and health-span, are likely to have inherited facilitatory gene groups, but also have nine decades of life experiences and behaviours which have interacted with their genetic profiles. Identification of their shared genes is just one small step in the link from genes to their physical and psychological profiles. Behavioural genomics is beginning to demonstrate links to biological mechanisms through regulation of gene expression, which directs the proteome and influences the personal phenotype. Epigenetics has been considered the missing link between nature and nurture. Although there is much that remains to be discovered, this article will discuss some of genetic and environmental factors which appear important in good quality longevity and link known epigenetic mechanisms to themes identified by nonagenarians themselves related to their longevity. Here we suggest that exceptional 90-year old siblings have adopted a range of behaviours and life-styles which have contributed to their ageing-well-phenotype and which link with important public health messages.]]>
Thu, 02 Jul 2015 00:00:00 PDT
Biomarkers in Neonatology: The New "Omics" Of Bronchopulmonary Dysplasia. Piersigilli F, Bhandari V
J Matern Fetal Neonatal Med (Jul 2015)

Bronchopulmonary dysplasia (BPD) is a complex disorder resulting from gene-environmental interactions. An improved understanding of the pathogenesis of this most common chronic lung disease in infants has been made by utilizing animal models and correlating with human data. Currently, while some (vitamin A, caffeine) pharmacotherapeutic options are being utilized to ameliorate this condition, there is still no specific or effective treatment for BPD. It would be helpful for prognostication and targeted potential novel therapeutic strategies to identify those babies accurately who are at risk for developing this disease. A reliable biomarker would have the capacity to be detected in the initial phase of the disease, to allow early interventions to avoid or minimize the detrimental effects of the disease. This review will focus on human studies performed with the "omic" techniques, specifically genomics, epigenomics, microbiomics, transciptomics, proteomics, and metabolomics, and summarize the information available in the literature, as it pertains to biomarker identification for BPD. Using "omics" technologies, investigators have reported markers that have the potential to be used as biomarkers of BPD: SPOCK2, VEGF -624C>G, VEGF -460T>C, mast cells specific markers, miR-219 pathway, miR-152, -30a-3p, -133b, -206, -7, lactate, taurine, trimethylamine-N-oxide, gluconate, myoinositol, and alterations in surfactant lipid profile.]]>
Thu, 02 Jul 2015 00:00:00 PDT
toxoMine: an integrated omics data warehouse for Toxoplasma gondii systems biology research. Rhee DB, Croken MM, Shieh KR, Sullivan J, Micklem G, Kim K, Golden A
Database (Oxford) (2015)

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that must monitor for changes in the host environment and respond accordingly; however, it is still not fully known which genetic or epigenetic factors are involved in regulating virulence traits of T. gondii. There are on-going efforts to elucidate the mechanisms regulating the stage transition process via the application of high-throughput epigenomics, genomics and proteomics techniques. Given the range of experimental conditions and the typical yield from such high-throughput techniques, a new challenge arises: how to effectively collect, organize and disseminate the generated data for subsequent data analysis. Here, we describe toxoMine, which provides a powerful interface to support sophisticated integrative exploration of high-throughput experimental data and metadata, providing researchers with a more tractable means toward understanding how genetic and/or epigenetic factors play a coordinated role in determining pathogenicity of T. gondii. As a data warehouse, toxoMine allows integration of high-throughput data sets with public T. gondii data. toxoMine is also able to execute complex queries involving multiple data sets with straightforward user interaction. Furthermore, toxoMine allows users to define their own parameters during the search process that gives users near-limitless search and query capabilities. The interoperability feature also allows users to query and examine data available in other InterMine systems, which would effectively augment the search scope beyond what is available to toxoMine. toxoMine complements the major community database ToxoDB by providing a data warehouse that enables more extensive integrative studies for T. gondii. Given all these factors, we believe it will become an indispensable resource to the greater infectious disease research community.Database URL: http://toxomine.org.]]>
Wed, 01 Jul 2015 00:00:00 PDT
Vitamin A induces inhibitory histone methylation modifications and down-regulates trained immunity in human monocytes. Arts RJ, Blok BA, van Crevel R, Joosten LA, Aaby P, Benn CS, Netea MG
J Leukoc Biol (Jul 2015)

Epidemiologic studies suggest that VAS has long-lasting immunomodulatory effects. We hypothesized that ATRA inhibits inflammatory cytokines in a model of trained immunity in monocytes by inducing epigenetic reprogramming through histone modifications. We used an previously described in vitro model of trained immunity, in which adherent monocytes of healthy volunteers were incubated for 24 h with BCG in the presence or absence of ATRA. After washing the cells, they were incubated for an additional 6 d in culture medium and restimulated with microbial ligands, and cytokine production was assessed. ATRA inhibited cytokine responses upon restimulation of monocytes, and this effect was exerted through increased expression of SUV39H2, a histone methyltransferase that induces the inhibitory mark H3K9me3. H3K9me3 at promoter sites of several cytokines was up-regulated by ATRA, and inhibition of SUV39H2 restored cytokine production. In addition to H3K9me3, the stimulatory histone mark H3K4me3 was down-regulated by ATRA at several promoter locations of cytokine genes. Therefore, we can conclude that ATRA inhibits cytokine production in models of direct stimulation or BCG-induced trained immunity and that these effects are mediated by histone modifications.]]>
Wed, 01 Jul 2015 00:00:00 PDT
Beckwith-Wiedemann syndrome prenatal diagnosis by methylation analysis in chorionic villi. Paganini L, Carlessi N, Fontana L, Silipigni R, Motta S, Fiori S, Guerneri S, Lalatta F, Cereda A, Sirchia S, Miozzo M, Tabano S
Epigenetics (Jul 2015)

Beckwith-Wiedemann syndrome (BWS) is an imprinting disorder that can be prenatally suspected or diagnosed based on established clinical guidelines. Molecular confirmation is commonly performed on amniocytes. The possibility to use fresh (CVF) and cultured (CVC) chorionic villi has never been investigated. To verify whether CVF and CVC are reliable sources of DNA to study fetal methylation, we used pyrosequencing to test the methylation level of a number of differentially methylated regions (DMRs) at several imprinted loci (ICR1, ICR2, H19, PWS/AS-ICR, GNASXL, GNAS1A, ZAC/PLAGL1, and MEST) and at non-imprinted MGMT and RASSF1A promoters. We analyzed these regions in 19 healthy pregnancies and highlighted stable methylation levels between CVF and CVC at ICR1, ICR2, GNASXL, PWS/AS-ICR, and MEST. Conversely, the methylation levels at H19 promoter, GNAS1A and ZAC/PLAGL1 were different in CVC compared to fresh CV. We also investigated ICR1 and ICR2 methylation level of CVF/CVC of 2 BWS-suspected fetuses (P1 and P2). P1 showed ICR2 hypomethylation, P2 showed normal methylation at both ICR1 and ICR2. Our findings, although limited to one case of BWS fetus with an imprinting defect, can suggest that ICR1 and ICR2, but not H19, could be reliable targets for prenatal BWS diagnosis by methylation test in CVF and CVC. In addition, PWS/AS-ICR, GNASXL, and MEST, but not GNAS1A and ZAC/PLAGL1, are steadily hemimethylated in CV from healthy pregnancies, independently from culture. Thus, prenatal investigation of genomic imprinting in CV needs to be validated in a locus-specific manner.]]>
Sat, 27 Jun 2015 00:00:00 PDT
Formalin-fixed, paraffin-embedded (FFPE) tissue epigenomics using Infinium HumanMethylation450 BeadChip assays. de Ruijter TC, de Hoon JP, Slaats J, de Vries B, Janssen MJ, van Wezel T, Aarts MJ, van Engeland M, Tjan-Heijnen VC, Van Neste L, Veeck J
Lab Invest (Jul 2015)

Current genome-wide methods to detect DNA-methylation in healthy and diseased tissue require high-quality DNA from fresh-frozen (FF) samples. However, well-annotated clinical samples are mostly available as formalin-fixed, paraffin-embedded (FFPE) tissues containing poor-quality DNA. To overcome this limitation, we here aimed to evaluate a DNA restoration protocol for usage with the genome-wide Infinium HumanMethylation450 BeadChip assay (HM-450K). Sixty-six DNA samples from normal colon (n=9) and breast cancer (n=11) were interrogated separately using HM-450K. Analyses included matched FF/FFPE samples and technical duplicates. FFPE DNA was processed with (FFPEr) or without a DNA restoration protocol (Illumina). Differentially methylated genes were finally validated in 24 additional FFPE tissues using nested methylation-specific PCR (MSP). In summary, β-values correlation between FFPEr duplicates was high (ρ=0.9927 (s.d. ±0.0015)). Matched FF/FFPEr correlation was also high (ρ=0.9590 (s.d. ±0.0184)) compared with matched FF/FFPE (ρ=0.8051 (s.d. ±0.1028). Probe detection rate in FFPEr samples (98.37%, s.d. ±0.66) was comparable to FF samples (99.98%, s.d. ±0.019) and substantially lower in FFPE samples (82.31%, s.d. ±18.65). Assay robustness was not decreased by sample archival age up to 10 years. We could also demonstrate no decrease in assay robustness when using 100 ng of DNA input only. Four out of the five selected differentially methylated genes could be validated by MSP. The gene failing validation by PCR showed high variation of CpG β-values in primer-binding sites. In conclusion, by using the FFPE DNA restoration protocol, HM-450K assays provide robust, accurate and reproducible results with FFPE tissue-derived DNA, which are comparable to those obtained with FF tissue. Most importantly, differentially methylated genes can be validated using more sensitive techniques, such as nested MSP, altogether providing an epigenomics platform for molecular pathological epidemiology research on archived samples with limited tissue amount.]]>
Fri, 26 Jun 2015 00:00:00 PDT
Chromatin Modifications Associated With Diabetes and Obesity. Schones DE, Leung A, Natarajan R
Arterioscler Thromb Vasc Biol (Jul 2015)

The incidence of obesity across the globe has doubled over the past several decades, leading to escalating rates of diabetes mellitus, cardiovascular disease, and other complications. Given this dramatic rise in disease incidence, understanding the cause of these diseases is therefore of paramount importance. Metabolic diseases, such as obesity and diabetes mellitus, result from a multitude of genetic and environmental factors. Although the genetic basis of these diseases has been extensively studied, the molecular pathways whereby environmental factors influence disease progression are only beginning to be understood. One manner by which environmental factors can contribute to disease progression is through modifications to chromatin. The highly structured packaging of the genome into the nucleus through chromatin has been shown to be fundamental to tissue-specific gene regulation. Modifications to chromatin can regulate gene expression and are involved in a myriad of biological functions, and hence, disruption of these modifications is central to many human diseases. These modifications can furthermore be epigenetic in nature, thereby contributing to prolonged disease risk. Recent work has demonstrated that modifications to chromatin are associated with the progression of both diabetes mellitus and obesity, which is the subject of this review.]]>
Thu, 25 Jun 2015 00:00:00 PDT
The potential for epigenetic analysis of paediatric CNS tumours to improve diagnosis, treatment and prognosis. Sexton-Oates A, MacGregor D, Dodgshun A, Saffery R
Ann Oncol (Jul 2015)

Tumours of central nervous system (CNS) origin are the second most prevalent group of cancers in children, yet account for the majority of childhood cancer-related deaths. Such tumours show diverse location, cell type of origin, disease course and long-term outcome, both across and within tumour types, making treatment problematic and contributing to the relatively modest progress in reducing mortality over recent decades. As technological advances begin to reveal the genetic landscape of all cancers, it is becoming increasingly clear that genetic disruption represents only one 'layer' of molecular disruption associated with disease aetiology. Obtaining a full understanding of tumour behaviour requires an understanding of the cellular and molecular pathways disrupted during tumourigenesis, particularly in relation to gene expression. The utility of such an approach has allowed stratification of cancers such as medulloblastoma into subgroups based on molecular features, with potential to refine risk prediction. Given that epigenetic disruption is a universal feature of all human cancers, it is logical to speculate that interrogating epigenetic marks may help to further define the molecular profile, and therefore the clinical trajectory, of tumours. An integrated approach to build a molecular 'signature' of individual tumours that incorporates traditional morphological and demographic information, genetic and transcriptome analysis, in addition to epigenomics (DNA methylation and non-coding RNA analysis), offers tremendous promise to (i) inform treatment approach, (ii) facilitate accurate early identification (preferably at diagnosis) of variable risk groups (both good and poor prognosis groups), and (iii) track disease progression in childhood CNS tumours.]]>
Thu, 25 Jun 2015 00:00:00 PDT
Chromatin Changes at the PPAR-γ2 Promoter During Bone Marrow-Derived Multipotent Stromal Cell Culture Correlate With Loss of Gene Activation Potential. Lynch PJ, Thompson EE, McGinnis K, Rovira Gonzalez YI, Lo Surdo J, Bauer SR, Hursh DA
Stem Cells (Jul 2015)

Bone marrow-derived multipotent stromal cells (BM-MSCs) display a broad range of therapeutically valuable properties, including the capacity to form skeletal tissues and dampen immune system responses. However, to use BM-MSCs in a clinical setting, amplification is required, which may introduce epigenetic changes that affect biological properties. Here we used chromatin immunoprecipitation to compare post-translationally modified histones at a subset of gene promoters associated with developmental and environmental plasticity in BM-MSCs from multiple donors following culture expansion. At many locations, we observed localization of both transcriptionally permissive (H3K4me3) and repressive (H3K27me3) histone modifications. These chromatin signatures were consistent among BM-MSCs from multiple donors. Since promoter activity depends on the relative levels of H3K4me3 and H3K27me3, we examined the ratio of H3K4me3 to H3K27me3 (K4/K27) at promoters during culture expansion. The H3K4me3 to H3K27me3 ratios were maintained at most assayed promoters over time. The exception was the adipose-tissue specific promoter for the PPAR-γ2 isoform of PPAR-γ, which is a critical positive regulator of adipogenesis. At PPAR-γ2, we observed a change in K4/K27 levels favoring the repressed chromatin state during culture. This change correlated with diminished promoter activity in late passage cells exposed to adipogenic stimuli. In contrast to BM-MSCs and osteoblasts, lineage-restricted preadipocytes exhibited levels of H3K4me3 and H3K27me3 that favored the permissive chromatin state at PPAR-γ2. These results demonstrate that locus-specific changes in H3K4me3 and H3K27me3 levels can occur during BM-MSC culture that may affect their properties. Stem Cells 2015;33:2169-2181.]]>
Tue, 23 Jun 2015 00:00:00 PDT
How did viviparity originate and evolve? Of conflict, co-option, and cryptic choice. Kalinka AT
Bioessays (Jul 2015)

I propose that the underlying adaptation enabling the reproductive strategy of birthing live young (viviparity) is retraction of the site of fertilization within the female reproductive tract, and that this evolved as a means of postcopulatory sexual selection. There are three conspicuous aspects associated with viviparity: (i) internal development is a complex trait often accompanied by a suite of secondary adaptations, yet it is unclear how the intermediate state of this trait - egg retention - could have evolved; (ii) viviparity often results in a reduction in fecundity; (iii) viviparity has evolved independently many times across a diverse array of animal groups. Focusing on the Diptera (true flies), I provide explanations for these observations. I further propose that fecundity is not traded-off to enable potential benefits of viviparity, but rather that loss of fecundity is directly selected and egg retention is an indirect consequence - a model that provides a unifying common basis for the ubiquity of viviparity.]]>
Tue, 23 Jun 2015 00:00:00 PDT
The Contributions of Nursing to Genetics, Epigenetics, Genomics, and Epigenomics: A Word From the Current President of ISONG. Alexander SA
Biol Res Nurs (Jul 2015)

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Thu, 18 Jun 2015 00:00:00 PDT
Proceedings of the second international molecular pathological epidemiology (MPE) meeting. Ogino S, Campbell PT, Nishihara R, Phipps AI, Beck AH, Sherman ME, Chan AT, Troester MA, Bass AJ, Fitzgerald KC, Irizarry RA, Kelsey KT, Nan H, Peters U, Poole EM, Qian ZR, Tamimi RM, Tchetgen Tchetgen EJ, Tworoger SS, Zhang X, Giovannucci EL, van den Brandt PA, Rosner BA, Wang M, Chatterjee N, Begg CB
Cancer Causes Control (Jul 2015)

Disease classification system increasingly incorporates information on pathogenic mechanisms to predict clinical outcomes and response to therapy and intervention. Technological advancements to interrogate omics (genomics, epigenomics, transcriptomics, proteomics, metabolomics, metagenomics, interactomics, etc.) provide widely open opportunities in population-based research. Molecular pathological epidemiology (MPE) represents integrative science of molecular pathology and epidemiology. This unified paradigm requires multidisciplinary collaboration between pathology, epidemiology, biostatistics, bioinformatics, and computational biology. Integration of these fields enables better understanding of etiologic heterogeneity, disease continuum, causal inference, and the impact of environment, diet, lifestyle, host factors (including genetics and immunity), and their interactions on disease evolution. Hence, the Second International MPE Meeting was held in Boston in December 2014, with aims to: (1) develop conceptual and practical frameworks; (2) cultivate and expand opportunities; (3) address challenges; and (4) initiate the effort of specifying guidelines for MPE. The meeting mainly consisted of presentations of method developments and recent data in various malignant neoplasms and tumors (breast, prostate, ovarian and colorectal cancers, renal cell carcinoma, lymphoma, and leukemia), followed by open discussion sessions on challenges and future plans. In particular, we recognized need for efforts to further develop statistical methodologies. This meeting provided an unprecedented opportunity for interdisciplinary collaboration, consistent with the purposes of the Big Data to Knowledge, Genetic Associations and Mechanisms in Oncology, and Precision Medicine Initiative of the US National Institute of Health. The MPE meeting series can help advance transdisciplinary population science and optimize training and education systems for twenty-first century medicine and public health.]]>
Sat, 13 Jun 2015 00:00:00 PDT
Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data. Kok-Sin T, Mokhtar NM, Ali Hassan NZ, Sagap I, Mohamed Rose I, Harun R, Jamal R
Oncol Rep (Jul 2015)

Apart from genetic mutations, epigenetic alteration is a common phenomenon that contributes to neoplastic transformation in colorectal cancer. Transcriptional silencing of tumor‑suppressor genes without changes in the DNA sequence is explained by the existence of promoter hypermethylation. To test this hypothesis, we integrated the epigenome and transcriptome data from a similar set of colorectal tissue samples. Methylation profiling was performed using the Illumina InfiniumHumanMethylation27 BeadChip on 55 paired cancer and adjacent normal epithelial cells. Fifteen of the 55 paired tissues were used for gene expression profiling using the Affymetrix GeneChip Human Gene 1.0 ST array. Validation was carried out on 150 colorectal tissues using the methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) technique. PCA and supervised hierarchical clustering in the two microarray datasets showed good separation between cancer and normal samples. Significant genes from the two analyses were obtained based on a ≥2‑fold change and a false discovery rate (FDR) p-value of <0.05. We identified 1,081 differentially hypermethylated CpG sites and 36 hypomethylated CpG sites. We also found 709 upregulated and 699 downregulated genes from the gene expression profiling. A comparison of the two datasets revealed 32 overlapping genes with 27 being hypermethylated with downregulated expression and 4 hypermethylated with upregulated expression. One gene was found to be hypomethylated and downregulated. The most enriched molecular pathway identified was cell adhesion molecules that involved 4 overlapped genes, JAM2, NCAM1, ITGA8 and CNTN1. In the present study, we successfully identified a group of genes that showed methylation and gene expression changes in well-defined colorectal cancer tissues with high purity. The integrated analysis gives additional insight regarding the regulation of colorectal cancer-associated genes and their underlying mechanisms that contribute to colorectal carcinogenesis.]]>
Thu, 11 Jun 2015 00:00:00 PDT
Maternal-fetal conflict, genomic imprinting and mammalian vulnerabilities to cancer. Haig D
Philos Trans R Soc Lond B Biol Sci (Jul 2015)

Antagonistic coevolution between maternal and fetal genes, and between maternally and paternally derived genes may have increased mammalian vulnerability to cancer. Placental trophoblast has evolved to invade maternal tissues and evade structural and immunological constraints on its invasion. These adaptations can be co-opted by cancer in intrasomatic selection. Imprinted genes of maternal and paternal origin favour different degrees of proliferation of particular cell types in which they reside. As a result, the set of genes favouring greater proliferation will be selected to evade controls on cell-cycle progression imposed by the set of genes favouring lesser proliferation. The dynamics of stem cell populations will be a particular focus of this intragenomic conflict. Gene networks that are battlegrounds of intragenomic conflict are expected to be less robust than networks that evolve in the absence of conflict. By these processes, maternal-fetal and intragenomic conflicts may undermine evolved defences against cancer.]]>
Tue, 09 Jun 2015 00:00:00 PDT
Ultrasensitive homogeneous electrochemical strategy for DNA methyltransferase activity assay based on autonomous exonuclease III-assisted isothermal cycling signal amplification. Li W, Liu X, Hou T, Li H, Li F
Biosens Bioelectron (Aug 2015)

DNA methylation catalyzed by methyltransferase (MTase) plays an important role in many biological processes, including gene transcription, genomic imprinting and cellular differentiation. Herein, a simple and novel homogeneous electrochemical strategy for ultrasensitive DNA MTase activity assay has been successfully developed, which is based on methylation-triggered exonuclease (Exo) III-assisted autonomous isothermal cycling signal amplification. A duplex DNA (P1-P2 hybrid) containing the methylation-responsive sequence is ingeniously designed. In the presence of DNA adenine methylation (Dam) methyltransferase (MTase), P1-P2 hybrid is methylated and subsequently recognized and cleaved by Dpn I endonuclease, which triggers the Exo III-catalyzed autonomous cycling cleavage processes. Therefore, a large amount of methylene blue-labeled mononucleotides are released, generating a significantly amplified electrochemical signal toward the Dam MTase activity assay. The directly measured detection limit down to 0.004U/mL is obtained, which is one or two orders magnitude lower than that of the approaches reported in literature. Since this assay is carried out in homogeneous solution phase under isothermal condition and sophisticated probe immobilization processes are avoided, it is very simple and easy to implement. Due to its advantages of ultrahigh sensitivity, excellent selectivity and simple operation, the as-proposed strategy has great potential in the applications in DNA methylation related clinical practices and biochemical researches.]]>
Sat, 30 May 2015 00:00:00 PDT
Aberrant methylation of imprinted genes is associated with negative hormone receptor status in invasive breast cancer. Barrow TM, Barault L, Ellsworth RE, Harris HR, Binder AM, Valente AL, Shriver CD, Michels KB
Int J Cancer (Aug 2015)

Epigenetic regulation of imprinted genes enables monoallelic expression according to parental origin, and its disruption is implicated in many cancers and developmental disorders. The expression of hormone receptors is significant in breast cancer because they are indicators of cancer cell growth rate and determine response to endocrine therapies. We investigated the frequency of aberrant events and variation in DNA methylation at nine imprinted sites in invasive breast cancer and examined the association with estrogen and progesterone receptor status. Breast tissue and blood from patients with invasive breast cancer (n = 38) and benign breast disease (n = 30) were compared with those from healthy individuals (n = 36), matched with the cancer patients by age at diagnosis, ethnicity, body mass index, menopausal status and familial history of cancer. DNA methylation and allele-specific expression were analyzed by pyrosequencing. Tumor-specific methylation changes at IGF2 DMR2 were observed in 59% of cancer patients, IGF2 DMR0 in 38%, DIRAS3 DMR in 36%, GRB10 ICR in 23%, PEG3 DMR in 21%, MEST ICR in 19%, H19 ICR in 18%, KvDMR in 8% and SNRPN/SNURF ICR in 4%. Variation in methylation was significantly greater in breast tissue from cancer patients compared with that in healthy individuals and benign breast disease. Aberrant methylation of three or more sites was significantly associated with negative estrogen-alpha (Fisher's exact test, p = 0.02) and progesterone-A (p = 0.02) receptor status. Aberrant events and increased variation in imprinted gene DNA methylation, therefore, seem to be frequent in invasive breast cancer and are associated with negative estrogen and progesterone receptor status, without loss of monoallelic expression.]]>
Mon, 18 May 2015 00:00:00 PDT
Pyrosequencing for accurate imprinted allele expression analysis. Yang B, Damaschke N, Yao T, McCormick J, Wagner J, Jarrard D
J Cell Biochem (Jul 2015)

Genomic imprinting is an epigenetic mechanism that restricts gene expression to one inherited allele. Improper maintenance of imprinting has been implicated in a number of human diseases and developmental syndromes. Assays are needed that can quantify the contribution of each paternal allele to a gene expression profile. We have developed a rapid, sensitive quantitative assay for the measurement of individual allelic ratios termed Pyrosequencing for Imprinted Expression (PIE). Advantages of PIE over other approaches include shorter experimental time, decreased labor, avoiding the need for restriction endonuclease enzymes at polymorphic sites, and prevent heteroduplex formation which is problematic in quantitative PCR-based methods. We demonstrate the improved sensitivity of PIE including the ability to detect differences in allelic expression down to 1%. The assay is capable of measuring genomic heterozygosity as well as imprinting in a single run. PIE is applied to determine the status of Insulin-like Growth Factor-2 (IGF2) imprinting in human and mouse tissues. J. Cell. Biochem. 116: 1165-1170, 2015. © 2015 Wiley Periodicals, Inc.]]>
Wed, 13 May 2015 00:00:00 PDT
Proteogenomics of the human hippocampus: The road ahead. Kang MG, Byun K, Kim JH, Park NH, Heinsen H, Ravid R, Steinbusch HW, Lee B, Park YM
Biochim Biophys Acta (Jul 2015)

The hippocampus is one of the most essential components of the human brain and plays an important role in learning and memory. The hippocampus has drawn great attention from scientists and clinicians due to its clinical importance in diseases such as Alzheimer's disease (AD), non-AD dementia, and epilepsy. Understanding the function of the hippocampus and related disease mechanisms requires comprehensive knowledge of the orchestration of the genome, epigenome, transcriptome, proteome, and post-translational modifications (PTMs) of proteins. The past decade has seen remarkable advances in the high-throughput sequencing techniques that are collectively called next generation sequencing (NGS). NGS enables the precise analysis of gene expression profiles in cells and tissues, allowing powerful and more feasible integration of expression data from the gene level to the protein level, even allowing "-omic" level assessment of PTMs. In addition, improved bioinformatics algorithms coupled with NGS technology are finally opening a new era for scientists to discover previously unidentified and elusive proteins. In the present review, we will focus mainly on the proteomics of the human hippocampus with an emphasis on the integrated analysis of genomics, epigenomics, transcriptomics, and proteomics. Finally, we will discuss our perspectives on the potential and future of proteomics in the field of hippocampal biology. This article is part of a Special Issue entitled: Neuroproteomics: Applications in Neuroscience and Neurology.]]>
Sat, 09 May 2015 00:00:00 PDT