Background: Although the association between cigarette smoking and risk of type 2 diabetes is well established, its mechanisms are yet to be clarified. This study examined the possible mediating effects of adiponectin, leptin, and C-reactive protein (CRP) concentrations on the smoking-diabetes association.Methods: Between 2002 and 2011, we followed 3338 Japanese workers, aged 35-66 years, who were enrolled in the second Aichi workers' cohort study. We used multivariable-adjusted Cox regression models to determine the hazard ratios and respective 95% confidence intervals (CIs) of the association between smoking status and risk of diabetes. A multiple mediation model with bootstrapping was used to estimate the magnitude and the respective bias-corrected (BC) 95% CIs of the indirect effects of smoking on diabetes through the three biomarkers.Results: Relative to never smokers, the risk of diabetes was significantly elevated in current (hazard ratio 1.75, 95% CI 1.25-2.46) and ex-smokers (hazard ratio 1.54, 95% CI 1.07-2.22). The indirect effects of smoking on diabetes through adiponectin levels were statistically significant among light (point estimate 0.033, BC 95% CI 0.005-0.082), moderate (point estimate 0.044, BC 95% CI 0.010-0.094), and heavy smokers (point estimate 0.054, BC 95% CI 0.013-0.113). In contrast, neither the indirect effects of smoking on diabetes through leptin nor CRP levels were significant, as the corresponding BC 95% CIs included zero.Conclusions: In our analysis, adiponectin concentration appeared to partially mediate the effect of smoking on diabetes, while leptin and CRP levels did not.
Although the global prevalence of both the overweight and obese is on the rise, there are variations among regions or countries, and sexes. Approximately half or more than half of the population are overweight/obese defined as body mass index ?25 kg/m(2)in the Americas (61.1%), Europe (54.8%), and Eastern Mediterranean (46.0%) according to the World Health Organization, while a much lower prevalence is observed in Africa (26.9%), South-East Asia (13.7%), and the Western Pacific (25.4%). Females are more likely to be overweight/obese in the Eastern Mediterranean, Africa, South-East Asia and the majority of countries in the Americas and Western Pacific but not in the most of the countries in Europe. These region-sex-ethnicity differences in prevalence may be a clue to the causes of the obesity epidemic. Epidemiological studies done in the USA, Europe, and Asia found that higher BMI was significantly associated with increased incidence of coronary artery disease (CAD) and ischemic stroke, but the association with hemorrhagic stroke incidence was not always consistent. The association of BMI with CAD and ischemic stroke was generally independent of known mediators, which would indicate the importance of controlling or preventing overweight/obesity for the prevention of cardiovascular disease.
Background: Findings regarding the association between milk consumption and all-cause mortality reported by studies carried out in Western populations have been inconsistent. However, no studies have been conducted in Japan on this issue. The present study aimed to investigate the association of milk drinking with all-cause, cardiovascular, and cancer mortality in Japan.Methods: The data were obtained from the Japan Collaborative Cohort (JACC) study. A total of 94 980 Japanese adults aged 40-79 years who had no history of cancer, stroke, or chronic cardiovascular diseases were followed between 1988 and 2009. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of mortalities were assessed using a Cox proportional hazard regression model and taking the lowest milk consumption group as the reference.Results: During a median of 19 years of follow-up, there were 21 775 deaths (28.8% and 35.3% from cardiovascular diseases and cancer, respectively). Drinking milk 1-2 times a month was associated with lower all-cause mortality in men compared to those who never drank milk (multivariable-adjusted HR 0.92; 95% CI, 0.85-0.99). In women, those who drank 3-4 times a week also had a lower mortality risk compared with those who never drank milk (HR 0.91; 95% CI 0.85-0.98). Inverse associations between drinking milk and mortality from cardiovascular diseases and cancer were found only in men.Conclusions: Drinking milk at least 1-2 times a month was associated with lower all-cause mortality in men compared to never drinking milk. An inverse association was also found between drinking milk and mortality from both cardiovascular diseases and cancer. However, lower all-cause mortality in women was found only in those who drank milk 3-4 times/week.
Viral infection triggers innate immune signaling, which in turn induces interferon-? (IFN-?) production to establish innate antiviral immunity. Previous studies showed that Gcn5 (Kat2a), a histone acetyltransferase (HAT) with partial functional redundancy with PCAF (Kat2b), and Gcn5/PCAF-mediated histone H3K9 acetylation (H3K9ac) are enriched on the active IFNB gene promoter. However, whether Gcn5/PCAF and H3K9ac regulate IFN-? production is unknown. Here, we show that Gcn5/PCAF-mediated H3K9ac correlates well with, but is surprisingly dispensable for, the expression of endogenous IFNB and the vast majority of active genes in fibroblasts. Instead, Gcn5/PCAF repress IFN-? production and innate antiviral immunity in several cell types in a HAT-independent and non-transcriptional manner: by inhibiting the innate immune signaling kinase TBK1 in the cytoplasm. Our results thus identify Gcn5 and PCAF as negative regulators of IFN-? production and innate immune signaling.
To examine the association of intrahepatic fat with homeostasis model assessment-insulin resistance (HOMA-IR), a marker of insulin resistance, in Japanese adults, and whether intrahepatic fat is associated with insulin resistance independent of waist circumference and other measures of obesity.
The acetyltransferase Gcn5 is critical for embryogenesis and shows partial functional redundancy with its homolog PCAF. However, the tissue- and cell lineage-specific functions of Gcn5 and PCAF are still not well defined. Here we probe the functions of Gcn5 and PCAF in adipogenesis. We found that the double knockout (DKO) of Gcn5/PCAF inhibits expression of the master adipogenic transcription factor gene PPAR?, thereby preventing adipocyte differentiation. The adipogenesis defects in Gcn5/PCAF DKO cells are rescued by ectopic expression of peroxisome proliferator-activated receptor ? (PPAR?), suggesting Gcn5/PCAF act upstream of PPAR? to facilitate adipogenesis. The requirement of Gcn5/PCAF for PPAR? expression was unexpectedly bypassed by prolonged treatment with an adipogenic inducer, 3-isobutyl-1-methylxanthine (IBMX). However, neither PPAR? ectopic expression nor prolonged IBMX treatment rescued defects in Prdm16 expression in DKO cells, indicating that Gcn5/PCAF are essential for normal Prdm16 expression. Gcn5/PCAF regulate PPAR? and Prdm16 expression at different steps in the transcription process, facilitating RNA polymerase II recruitment to Prdm16 and elongation of PPAR? transcripts. Overall, our study reveals that Gcn5/PCAF facilitate adipogenesis through regulation of PPAR? expression and regulate brown adipogenesis by influencing Prdm16 expression.
The Sonic hedgehog (Shh) signalling pathway plays important roles during development and in cancer. Here we report a Shh-induced epigenetic switch that cooperates with Gli to control transcription outcomes. Before induction, poised Shh target genes are marked by a bivalent chromatin domain containing a repressive histone H3K27me3 mark and an active H3K4me3 mark. Shh activation induces a local switch of epigenetic cofactors from the H3K27 methyltransferase polycomb repressive complex 2 (PRC2) to an H3K27me3 demethylase Jmjd3/Kdm6b-centred coactivator complex. We also find that non-enzymatic activities of Jmjd3 are important and that Jmjd3 recruits the Set1/MLL H3K4 methyltransferase complexes in a Shh-dependent manner to resolve the bivalent domain. In vivo, changes of the bivalent domain accompanied Shh-activated cerebellar progenitor proliferation. Overall, our results reveal a regulatory mechanism that underlies the activation of Shh target genes and provides insight into the causes of various diseases and cancers exhibiting altered Shh signalling.
Enhancers play a central role in cell-type-specific gene expression and are marked by H3K4me1/2. Active enhancers are further marked by H3K27ac. However, the methyltransferases responsible for H3K4me1/2 on enhancers remain elusive. Furthermore, how these enzymes function on enhancers to regulate cell-type-specific gene expression is unclear. In this study, we identify MLL4 (KMT2D) as a major mammalian H3K4 mono- and di-methyltransferase with partial functional redundancy with MLL3 (KMT2C). Using adipogenesis and myogenesis as model systems, we show that MLL4 exhibits cell-type- and differentiation-stage-specific genomic binding and is predominantly localized on enhancers. MLL4 co-localizes with lineage-determining transcription factors (TFs) on active enhancers during differentiation. Deletion of Mll4 markedly decreases H3K4me1/2, H3K27ac, Mediator and Polymerase II levels on enhancers and leads to severe defects in cell-type-specific gene expression and cell differentiation. Together, these findings identify MLL4 as a major mammalian H3K4 mono- and di-methyltransferase essential for enhancer activation during cell differentiation. DOI: http://dx.doi.org/10.7554/eLife.01503.001.
Elevated high-sensitivity C-reactive protein (hs-CRP), a marker of low-grade systemic inflammation, may be involved in the etiology of type 2 diabetes mellitus (T2DM). However, whether inflammation precedes development of T2DM independent of cigarette smoking and obesity remains to be confirmed.
Histone chaperones affect chromatin structure and gene expression through interaction with histones and RNA polymerase II (PolII). Here, we report that the histone chaperone Spt6 counteracts H3K27me3, an epigenetic mark deposited by the Polycomb Repressive Complex 2 (PRC2) and associated with transcriptional repression. By regulating proper engagement and function of the H3K27 demethylase KDM6A (UTX), Spt6 effectively promotes H3K27 demethylation, muscle gene expression, and cell differentiation. ChIP-Seq experiments reveal an extensive genome-wide overlap of Spt6, PolII, and KDM6A at transcribed regions that are devoid of H3K27me3. Mammalian cells and zebrafish embryos with reduced Spt6 display increased H3K27me3 and diminished expression of the master regulator MyoD, resulting in myogenic differentiation defects. As a confirmation for an antagonistic relationship between Spt6 and H3K27me3, inhibition of PRC2 permits MyoD re-expression in myogenic cells with reduced Spt6. Our data indicate that, through cooperation with PolII and KDM6A, Spt6 orchestrates removal of H3K27me3, thus controlling developmental gene expression and cell differentiation.
Histone acetyltransferases (HATs) GCN5 and PCAF (GCN5/PCAF) and CBP and p300 (CBP/p300) are transcription co-activators. However, how these two distinct families of HATs regulate gene activation remains unclear. Here, we show deletion of GCN5/PCAF in cells specifically and dramatically reduces acetylation on histone H3K9 (H3K9ac) while deletion of CBP/p300 specifically and dramatically reduces acetylations on H3K18 and H3K27 (H3K18/27ac). A ligand for nuclear receptor (NR) PPAR? induces sequential enrichment of H3K18/27ac, RNA polymerase II (Pol II) and H3K9ac on PPAR? target gene Angptl4 promoter, which correlates with a robust Angptl4 expression. Inhibiting transcription elongation blocks ligand-induced H3K9ac, but not H3K18/27ac, on the Angptl4 promoter. Finally, we show GCN5/PCAF and GCN5/PCAF-mediated H3K9ac correlate with, but are surprisingly dispensable for, NR target gene activation. In contrast, CBP/p300 and their HAT activities are essential for ligand-induced Pol II recruitment on, and activation of, NR target genes. These results highlight the substrate and site specificities of HATs in cells, demonstrate the distinct roles of GCN5/PCAF- and CBP/p300-mediated histone acetylations in gene activation, and suggest an important role of CBP/p300-mediated H3K18/27ac in NR-dependent transcription.
Heparan sulfate proteoglycans (HSPGs) are required for various signaling pathways, one of which is the bone morphogenetic protein (BMP) signaling pathway. N-deacetylase/N-sulfotransferase-1 (NDST1) participates in synthesizing heparan sulfate (HS) chains of HSPGs, and is involved in bone and lung development. Here, we report that in spite of the redundant expression of Ndst2, Ndst3 and Ndst4 genes, Ndst1(-/-) mice display defective differentiation of lung cells and increased cell proliferation. Loss of Ndst1 in the lung enhances downstream BMP signaling in vivo. Noggin, which is an antagonist of BMP, can rescue the Ndst1(-/-) lung morphogenetic defects in explant cultures. Further studies in vitro indicated that loss of Ndst1 significantly impairs BMP internalization by decreasing BMP binding to endogenous HS. Exogenous heparin can rescue both the BMP signaling and BMP internalization abnormalities in Ndst1(-/-) lung. Thus, we propose that HS regulates BMP signaling by controlling the balance between BMP binding to HS, and that BMP receptors and NDST1-dependent modification are essential for this process. The results suggest that NDST1-dependent HS is essential for proper functioning of BMP in embryonic lung development.
Chromatin modifications have been implicated in the self-renewal and differentiation of embryonic stem cells (ESCs). However, the function of histone variant H2A.Z in ESCs remains unclear. We show that H2A.Z is highly enriched at promoters and enhancers and is required for both efficient self-renewal and differentiation of murine ESCs. H2A.Z deposition leads to an abnormal nucleosome structure, decreased nucleosome occupancy, and increased chromatin accessibility. In self-renewing ESCs, knockdown of H2A.Z compromises OCT4 binding to its target genes and leads to decreased binding of MLL complexes to active genes and of PRC2 complex to repressed genes. During differentiation of ESCs, inhibition of H2A.Z also compromises RA-induced RAR? binding, activation of differentiation markers, and the repression of pluripotency genes. We propose that H2A.Z mediates such contrasting activities by acting as a general facilitator that generates access for a variety of complexes, both activating and repressive.
To investigate the role of histone H3K27 demethylase UTX in embryonic stem (ES) cell differentiation, we have generated UTX knockout (KO) and enzyme-dead knock-in male ES cells. Deletion of the X-chromosome-encoded UTX gene in male ES cells markedly decreases expression of the paralogous UTY gene encoded by Y chromosome, but has no effect on global H3K27me3 level, Hox gene expression, or ES cell self-renewal. However, UTX KO cells show severe defects in mesoderm differentiation and induction of Brachyury, a transcription factor essential for mesoderm development. Surprisingly, UTX regulates mesoderm differentiation and Brachyury expression independent of its enzymatic activity. UTY, which lacks detectable demethylase activity, compensates for the loss of UTX in regulating Brachyury expression. UTX and UTY bind directly to Brachyury promoter and are required for Wnt/?-catenin signaling-induced Brachyury expression in ES cells. Interestingly, male UTX KO embryos express normal levels of UTY and survive until birth. In contrast, female UTX KO mice, which lack the UTY gene, show embryonic lethality before embryonic day 11.5. Female UTX KO embryos show severe defects in both Brachyury expression and embryonic development of mesoderm-derived posterior notochord, cardiac, and hematopoietic tissues. These results indicate that UTX controls mesoderm differentiation and Brachyury expression independent of H3K27 demethylase activity, and suggest that UTX and UTY are functionally redundant in ES cell differentiation and early embryonic development.
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