H2A.Z Acidic Patch Couples Chromatin Dynamics to Regulation of Gene Expression Programs during ESC Differentiation

The histone H2A variant H2A.Z is essential for embryonic development and for proper control of developmental gene expression programs in embryonic stem cells (ESCs). Divergent regions of amino acid sequence of H2A.Z likely determine its functional specialization compared to core histone H2A. For example, H2A.Z contains three divergent residues in the essential C-terminal acidic patch that reside on the surface of the histone octamer as an uninterrupted acidic patch domain; however, we know little about how these residues contribute to chromatin structure and function. Here, we show that the divergent amino acids Gly92, Asp97, and Ser98 in the H2A.Z C-terminal acidic patch (H2A.Z[superscript AP3]) are critical for lineage commitment during ESC differentiation. H2A.Z is enriched at most H3K4me3 promoters in ESCs including poised, bivalent promoters that harbor both activating and repressive marks, H3K4me3 and H3K27me3 respectively. We found that while H2A.Z[superscript AP3] interacted with its deposition complex and displayed a highly similar distribution pattern compared to wild-type H2A.Z, its enrichment levels were reduced at target promoters. Further analysis revealed that H2A.Z[superscript AP3] was less tightly associated with chromatin, suggesting that the mutant is more dynamic. Notably, bivalent genes in H2A.Z[superscript AP3] ESCs displayed significant changes in expression compared to active genes. Moreover, bivalent genes in H2A.Z[superscript AP3] ESCs gained H3.3, a variant associated with higher nucleosome turnover, compared to wild-type H2A.Z. We next performed single cell imaging to measure H2A.Z dynamics. We found that H2A.Z[superscript AP3] displayed higher mobility in chromatin compared to wild-type H2A.Z by fluorescent recovery after photobleaching (FRAP). Moreover, ESCs treated with the transcriptional inhibitor flavopiridol resulted in a decrease in the H2A.Z[superscript AP3] mobile fraction and an increase in its occupancy at target genes indicating that the mutant can be properly incorporated into chromatin. Collectively, our work suggests that the divergent residues in the H2A.Z acidic patch comprise a unique domain that couples control of chromatin dynamics to the regulation of developmental gene expression patterns during lineage commitment.Massachusetts Life Sciences Center (David H. Koch Institute for Integrative Cancer Research at MIT Core Grant P30-CA14051)National Science Foundation (U.S.). Emergent Behaviors of Integrated Cellular Systems (Grant CBET-0939511)MIT Faculty Start-up FundMassachusetts Institute of Technology. Computational and Systems Biology Initiative (Merck & Co. Postdoctoral Fellowship

Lifetime physical activity and risk of breast cancer in pre-and post-menopausal women

© 2015 Springer Science+Business Media New York To investigate the association between different types of physical activity (PA) and breast cancer. A case–control study of breast cancer was conducted in Western Australia from 2009 to 2011, in which 1205 women with breast cancer and 1789 frequency age-matched breast cancer-free control women were recruited. A self-administered questionnaire was used to collect information about lifetime and age-period recreational, household, occupational and transport physical activities. Detailed questions about demographic characteristics, and relevant reproductive, medical and lifestyle factors were also included. Logistic regression and restrictive cubic spline analyses were applied to investigate the association and dose–response relationship between PA and breast cancer risk. Subgroup analysis was performed regarding menopausal status. We found non-linear dose–response associations between PA and risk of breast cancer. Overall, 95–130 MET-hours/week of total lifetime PA was associated with the lowest breast cancer risk. The effects were stronger among post-menopausal women. We also found that the medium amounts of recreational PA (up to 21 MET-hours/week) were associated with lower breast cancer risk among post-menopausal women. Further analysis on the intensity of recreational PA demonstrated different dose–response associations between moderate- and vigorous-intensity recreational PA and breast cancer risk. We found that PA was associated with a reduced risk of breast cancer among post-menopausal women, but not in a linear fashion. Recreational PA of different intensities may have different dose–response associations with risk of breast cancer

The 5-HTTLPR polymorphism of the serotonin transporter gene and short term behavioral response to methylphenidate in children with ADHD

<p>Abstract</p> <p>Background</p> <p>Animal models of ADHD suggest that the paradoxical calming effect of methylphenidate on motor activity could be mediated through its action on serotonin transmission. In this study, we have investigated the relationship between the 5-HTTLPR polymorphism in the serotonin transporter gene (<it>SLC6A4</it>) and the response of ADHD relevant behaviors with methylphenidate treatment.</p> <p>Methods</p> <p>Patients between ages 6-12 (n = 157) were assessed with regard to their behavioral response to methylphenidate (0.5 mg/kg/day) using a 2-week prospective within-subject, placebo-controlled (crossover) trial. The children were then genotyped with regard to the triallelic 5-HTTLPR polymorphism in the <it>SLC6A4 </it>gene. Main outcome measure: Conners' Global Index for parents (CGI-Parents) and teachers (CGI-Teachers) at baseline and at the end of each week of treatment with placebo and methylphenidate. For both outcome measurements, we used a mixed model analysis of variance to determine gene, treatment and gene × treatment interaction effects.</p> <p>Results</p> <p>Mixed model analysis of variance revealed a gene × treatment interaction for CGI-Parents but not for CGI-Teachers. Children homozygous for the lower expressing alleles (<it>s+l_G= s'</it>) responded well to placebo and did not derive additional improvement with methylphenidate compared to children carrying a higher expressing allele (<it>l_A</it>). No genotype main effects on either CGI-Parents or CGI-teachers were observed.</p> <p>Conclusions</p> <p>A double blind placebo-controlled design was used to assess the behavioral effects of methylphenidate in relation to the triallelic 5-HTTLPR polymorphism of the <it>SLC6A4 </it>gene in children with ADHD. This polymorphism appears to modulate the behavioral response to methylphenidate in children with ADHD as assessed in the home environment by parents. Further investigation is needed to assess the clinical implications of this finding.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT00483106</p

Exploitation of Herpesviral Transactivation Allows Quantitative Reporter Gene-Based Assessment of Virus Entry and Neutralization

Herpesviral entry is a highly elaborated process requiring many proteins to act in precise conjunction. Neutralizing antibodies interfere with this process to abrogate viral infection. Based on promoter transactivation of a reporter gene we established a novel method to quantify herpesvirus entry and neutralization by antibodies. Following infection with mouse and human cytomegalovirus and Herpes simplex virus 1 we observed promoter transactivation resulting in substantial luciferase expression (>1000-fold). No induction was elicited by UV-inactivated viruses. The response was MOI-dependent and immunoblots confirmed a correlation between luciferase induction and pp72-IE1 expression. Monoclonal antibodies, immune sera and purified immunoglobulin preparations decreased virus-dependent luciferase induction dose-dependently, qualifying this approach as surrogate virus neutralization test. Besides the reduced hands-on time, this assay allows analysis of herpesvirus entry in semi-permissive and non-adherent cells, which were previously non-assessable but play significant roles in herpesvirus pathology

Polymorphisms of TP53 codon 72 with breast carcinoma risk: evidence from 12226 cases and 10782 controls

<p>Abstract</p> <p>Background</p> <p>Previously, TP53 codon 72 polymorphisms have been implicated as risk factors for various cancers. A number of studies have conducted on the association of TP53 codon 72 polymorphisms with susceptibility to breast carcinoma and have yielded inconclusive results. The aim of the present study was to derive a more precise estimation of the relationship.</p> <p>Methods</p> <p>We conducted a search in the Medline, EMBASE, OVID, Sciencedirect, and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published up to Jan 2009. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications.</p> <p>Results</p> <p>A total of seventeen case-control studies, including 12226 cases and 10782 controls, met the included criteria and thus were selected. Ultimately, the relevant data were extracted and further analyzed using systematic meta-analyses. Overall, no associations of TP53 codon 72 polymorphisms with breast carcinoma were observed (for Arg/Arg vs Pro/Pro: OR = 1.20; 95%CI = 0.96–1.50; for dominant model: OR = 1.12; 95%CI = 0.96–1.32; for recessive model: OR = 1.13; 95%CI = 0.98–1.31). In the subgroup analysis by ethnicity, statistically similar results were obtained when the data were stratified as Asians, Caucasians and Africans.</p> <p>Conclusion</p> <p>Collectively, the results of the present study suggest that <it>TP53 codon 72 </it>polymorphisms might not be a low-penetrant risk factor for developing breast carcinoma.</p

Systematic review on quality control for drug management programs: Is quality reported in the literature?

<p>Abstract</p> <p>Background</p> <p>Maintaining quality of care while managing limited healthcare resources is an ongoing challenge in healthcare. The objective of this study was to evaluate how the impact of drug management programs is reported in the literature and to identify potentially existing quality standards.</p> <p>Methods</p> <p>This analysis relates to the published research on the impact of drug management on economic, clinical, or humanistic outcomes in managed care, indemnity insurance, VA, or Medicaid in the USA published between 1996 and 2007. Included articles were systematically analyzed for study objective, study endpoints, and drug management type. They were further categorized by drug management tool, primary objective, and study endpoints.</p> <p>Results</p> <p>None of the 76 included publications assessed the overall quality of drug management tools. The impact of 9 different drug management tools used alone or in combination was studied in pharmacy claims, medical claims, electronic medical records or survey data from either patient, plan or provider perspective using an average of 2.1 of 11 possible endpoints. A total of 68% of the studies reported the impact on plan focused endpoints, while the clinical, the patient or the provider perspective were studied to a much lower degree (45%, 42% and 12% of the studies). Health outcomes were only accounted for in 9.2% of the studies.</p> <p>Conclusion</p> <p>Comprehensive assessment of quality considering plan, patient and clinical outcomes is not yet applied. There is no defined quality standard. Benchmarks including health outcomes should be determined and used to improve the overall clinical and economic effectiveness of drug management programs.</p

Quantitative and Molecular Genetic Analyses of Mutations Increasing Drosophila Life Span

Understanding the genetic and environmental factors that affect variation in life span and senescence is of major interest for human health and evolutionary biology. Multiple mechanisms affect longevity, many of which are conserved across species, but the genetic networks underlying each mechanism and cross-talk between networks are unknown. We report the results of a screen for mutations affecting Drosophila life span. One third of the 1,332 homozygous P–element insertion lines assessed had quantitative effects on life span; mutations reducing life span were twice as common as mutations increasing life span. We confirmed 58 mutations with increased longevity, only one of which is in a gene previously associated with life span. The effects of the mutations increasing life span were highly sex-specific, with a trend towards opposite effects in males and females. Mutations in the same gene were associated with both increased and decreased life span, depending on the location and orientation of the P–element insertion, and genetic background. We observed substantial—and sex-specific—epistasis among a sample of ten mutations with increased life span. All mutations increasing life span had at least one deleterious pleiotropic effect on stress resistance or general health, with different patterns of pleiotropy for males and females. Whole-genome transcript profiles of seven of the mutant lines and the wild type revealed 4,488 differentially expressed transcripts, 553 of which were common to four or more of the mutant lines, which include genes previously associated with life span and novel genes implicated by this study. Therefore longevity has a large mutational target size; genes affecting life span have variable allelic effects; alleles affecting life span exhibit antagonistic pleiotropy and form epistatic networks; and sex-specific mutational effects are ubiquitous. Comparison of transcript profiles of long-lived mutations and the control line reveals a transcriptional signature of increased life span

The P2X1 receptor and platelet function

Extracellular nucleotides are ubiquitous signalling molecules, acting via the P2 class of surface receptors. Platelets express three P2 receptor subtypes, ADP-dependent P2Y1 and P2Y12 G-protein-coupled receptors and the ATP-gated P2X1 non-selective cation channel. Platelet P2X1 receptors can generate significant increases in intracellular Ca2+, leading to shape change, movement of secretory granules and low levels of αIIbβ3 integrin activation. P2X1 can also synergise with several other receptors to amplify signalling and functional events in the platelet. In particular, activation of P2X1 receptors by ATP released from dense granules amplifies the aggregation responses to low levels of the major agonists, collagen and thrombin. In vivo studies using transgenic murine models show that P2X1 receptors amplify localised thrombosis following damage of small arteries and arterioles and also contribute to thromboembolism induced by intravenous co-injection of collagen and adrenaline. In vitro, under flow conditions, P2X1 receptors contribute more to aggregate formation on collagen-coated surfaces as the shear rate is increased, which may explain their greater contribution to localised thrombosis in arterioles compared to venules within in vivo models. Since shear increases substantially near sites of stenosis, anti-P2X1 therapy represents a potential means of reducing thrombotic events at atherosclerotic plaques