1
|
STAT5 Regulation of Sex-Dependent Hepatic CpG Methylation at Distal Regulatory Elements Mapping to Sex-Biased Genes. Mol Cell Biol 2021; 41:MCB.00166-20. [PMID: 33199496 DOI: 10.1128/mcb.00166-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 11/05/2020] [Indexed: 12/19/2022] Open
Abstract
Growth hormone-activated STAT5b is an essential regulator of sex-differential gene expression in mouse liver; however, its impact on hepatic gene expression and epigenetic responses is poorly understood. Here, we found a substantial, albeit incomplete loss of liver sex bias in hepatocyte-specific STAT5a/STAT5b (collectively, STAT5)-deficient mouse liver. In male liver, many male-biased genes were downregulated in direct association with the loss of STAT5 binding; many female-biased genes, which show low STAT5 binding, were derepressed, indicating an indirect mechanism for repression by STAT5. Extensive changes in CpG methylation were seen in STAT5-deficient liver, where sex differences were abolished at 88% of ∼1,500 sex-differentially methylated regions, largely due to increased DNA methylation upon STAT5 loss. STAT5-dependent CpG hypomethylation was rarely found at proximal promoters of STAT5-dependent genes. Rather, STAT5 primarily regulated the methylation of distal enhancers, where STAT5 deficiency induced widespread hypermethylation at genomic regions enriched for accessible chromatin, enhancer histone marks (histone H3 lysine 4 monomethylation [H3K4me1] and histone H3 lysine 27 acetylation [H3K27ac]), STAT5 binding, and DNA motifs for STAT5 and other transcription factors implicated in liver sex differences. Thus, the sex-dependent binding of STAT5 to liver chromatin is closely linked to the sex-dependent demethylation of distal regulatory elements linked to STAT5-dependent genes important for liver sex bias.
Collapse
|
2
|
Lkhagvadorj K, Meyer KF, Verweij LP, Kooistra W, Reinders-Luinge M, Dijkhuizen HW, de Graaf IAM, Plösch T, Hylkema MN. Prenatal smoke exposure induces persistent Cyp2a5 methylation and increases nicotine metabolism in the liver of neonatal and adult male offspring. Epigenetics 2020; 15:1370-1385. [PMID: 32573327 PMCID: PMC7678918 DOI: 10.1080/15592294.2020.1782655] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/12/2020] [Accepted: 05/15/2020] [Indexed: 02/08/2023] Open
Abstract
Prenatal smoke exposure (PSE) is a risk factor for nicotine dependence. One susceptibility gene for nicotine dependence is Cytochrome P450 (CYP) 2A6, an enzyme responsible for the conversion of nicotine to cotinine and nicotine clearance in the liver. Higher activity of the CYP2A6 enzyme is associated with nicotine dependence, but no research has addressed the PSE effects on the CYP2A6 gene or its mouse homologue Cyp2a5. We hypothesized that PSE affects Cyp2a5 promoter methylation, Cyp2a5 mRNA levels, and nicotine metabolism in offspring. We used a smoke-exposed pregnant mouse model. RNA, DNA, and microsomal protein were isolated from liver tissue of foetal, neonatal, and adult offspring. Enzyme activity, Cyp2a5 mRNA levels, and Cyp2a5 methylation status of six CpG sites within the promoter region were analysed via HPLC, RT-PCR, and bisulphite pyrosequencing. Our data show that PSE induced higher cotinine levels in livers of male neonatal and adult offspring compared to controls. PSE-induced cotinine levels in neonates correlated with Cyp2a5 mRNA expression and promoter methylation at CpG-7 and CpG+45. PSE increased methylation in almost all CpG sites in foetal offspring, and this effect persisted at CpG-74 in male neonatal and adult offspring. Our results indicate that male offspring of mothers which were exposed to cigarette smoke during pregnancy have a higher hepatic nicotine metabolism, which could be regulated by DNA methylation. Given the detected persistence into adulthood, extrapolation to the human situation suggests that sons born from smoking mothers could be more susceptible to nicotine dependence later in life.
Collapse
Affiliation(s)
- Khosbayar Lkhagvadorj
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Pulmonology and Allergology, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
| | - Karolin F. Meyer
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Laura P. Verweij
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Wierd Kooistra
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marjan Reinders-Luinge
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Henk W. Dijkhuizen
- Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands
| | - Inge A. M. de Graaf
- Department of Pharmacokinetics, Toxicology, and Targeting, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Torsten Plösch
- Department of Obstetrics and Gynecology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Machteld N. Hylkema
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| |
Collapse
|
3
|
Meyer KF, Verkaik-Schakel RN, Timens W, Kobzik L, Plösch T, Hylkema MN. The fetal programming effect of prenatal smoking on Igf1r and Igf1 methylation is organ- and sex-specific. Epigenetics 2018; 12:1076-1091. [PMID: 29160127 PMCID: PMC5810788 DOI: 10.1080/15592294.2017.1403691] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The impact of prenatal smoke exposure (PSE) on DNA methylation has been demonstrated in blood samples from children of smoking mothers, but evidence for sex-dependent smoke-induced effects is limited. As the identified differentially methylated genes can be associated with developmental processes, and insulin-like growth factors (IGFs) play a critical role in prenatal tissue growth, we hypothesized that PSE induces fetal programming of Igf1r and Igf1. Using a mouse model of smoking during pregnancy, we show that PSE alters promoter methylation of Igf1r and Igf1 and deregulates their gene expression in lung and liver of fetal (E17.5) and neonatal (D3) mouse offspring. By further comparing female versus male, lung versus liver, or fetal versus neonatal time point, our results demonstrate that CpG site-specific aberrant methylation patterns sex-dependently vary per organ and time point. Moreover, PSE reduces gene expression of Igf1r and Igf1, dependent on organ, sex, and offspring's age. Our results indicate that PSE may be a source of organ-specific rather than general systemic fetal programming. This is exemplified here by gene promoter methylation and mRNA levels of Igf1r and Igf1, together with a sex- and organ-specific naturally established correlation of both parameters that is affected by prenatal smoke exposure. Moreover, the comparison of fetuses with neonates suggests a CpG site-dependent reversibility/persistence of PSE-induced differential methylation patterns.
Collapse
Affiliation(s)
- Karolin F Meyer
- a Department of Pathology and Medical Biology , University of Groningen, University Medical Center Groningen , Hanzeplein 1, EA10, 9713 GZ , Groningen , The Netherlands.,b University of Groningen , University Medical Center Groningen , GRIAC Research Institute , Hanzeplein 1, EA10, 9713 GZ , Groningen , The Netherlands
| | - Rikst Nynke Verkaik-Schakel
- c Department of Obstetrics and Gynaecology , University of Groningen , University Medical Center Groningen , Hanzeplein 1, 9713 GZ , Groningen , The Netherlands
| | - Wim Timens
- a Department of Pathology and Medical Biology , University of Groningen, University Medical Center Groningen , Hanzeplein 1, EA10, 9713 GZ , Groningen , The Netherlands.,b University of Groningen , University Medical Center Groningen , GRIAC Research Institute , Hanzeplein 1, EA10, 9713 GZ , Groningen , The Netherlands
| | - Lester Kobzik
- d Molecular and Integrative Physiological Sciences Program, Department of Environmental Health , Harvard T. H. Chan School of Public Health , Building II Room 221, 655 Huntington Avenue, Boston , MA 02115 , USA
| | - Torsten Plösch
- c Department of Obstetrics and Gynaecology , University of Groningen , University Medical Center Groningen , Hanzeplein 1, 9713 GZ , Groningen , The Netherlands
| | - Machteld N Hylkema
- a Department of Pathology and Medical Biology , University of Groningen, University Medical Center Groningen , Hanzeplein 1, EA10, 9713 GZ , Groningen , The Netherlands.,b University of Groningen , University Medical Center Groningen , GRIAC Research Institute , Hanzeplein 1, EA10, 9713 GZ , Groningen , The Netherlands
| |
Collapse
|
4
|
Fitzgerald E, Boardman JP, Drake AJ. Preterm Birth and the Risk of Neurodevelopmental Disorders - Is There a Role for Epigenetic Dysregulation? Curr Genomics 2018; 19:507-521. [PMID: 30386170 PMCID: PMC6158617 DOI: 10.2174/1389202919666171229144807] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 04/06/2017] [Accepted: 12/17/2017] [Indexed: 12/29/2022] Open
Abstract
Preterm Birth (PTB) accounts for approximately 11% of all births worldwide each year and is a profound physiological stressor in early life. The burden of neuropsychiatric and developmental impairment is high, with severity and prevalence correlated with gestational age at delivery. PTB is a major risk factor for the development of cerebral palsy, lower educational attainment and deficits in cognitive functioning, and individuals born preterm have higher rates of schizophrenia, autistic spectrum disorder and attention deficit/hyperactivity disorder. Factors such as gestational age at birth, systemic inflammation, respiratory morbidity, sub-optimal nutrition, and genetic vulnerability are associated with poor outcome after preterm birth, but the mechanisms linking these factors to adverse long term outcome are poorly understood. One potential mechanism linking PTB with neurodevelopmental effects is changes in the epigenome. Epigenetic processes can be defined as those leading to altered gene expression in the absence of a change in the underlying DNA sequence and include DNA methylation/hydroxymethylation and histone modifications. Such epigenetic modifications may be susceptible to environmental stimuli, and changes may persist long after the stimulus has ceased, providing a mechanism to explain the long-term consequences of acute exposures in early life. Many factors such as inflammation, fluctuating oxygenation and excitotoxicity which are known factors in PTB related brain injury, have also been implicated in epigenetic dysfunction. In this review, we will discuss the potential role of epigenetic dysregulation in mediating the effects of PTB on neurodevelopmental outcome, with specific emphasis on DNA methylation and the α-ketoglutarate dependent dioxygenase family of enzymes.
Collapse
Affiliation(s)
| | | | - Amanda J. Drake
- Address correspondence to this author at the University/BHF Centre for Cardiovascular Science, University of Edinburgh, The Queen’s Medical Research Institute, Edinburgh EH16 4TJ, UK; Tel: 44 131 2426748; Fax: 44 131 2426779; E-mail:
| |
Collapse
|
5
|
Sexually Dimorphic Expression of eGFP Transgene in the Akr1A1 Locus of Mouse Liver Regulated by Sex Hormone-Related Epigenetic Remodeling. Sci Rep 2016; 6:24023. [PMID: 27087367 PMCID: PMC4834580 DOI: 10.1038/srep24023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/14/2016] [Indexed: 12/19/2022] Open
Abstract
Sexually dimorphic gene expression is commonly found in the liver, and many of these genes are linked to different incidences of liver diseases between sexes. However, the mechanism of sexually dimorphic expression is still not fully understood. In this study, a pCAG-eGFP transgenic mouse strain with a specific transgene integration site in the Akr1A1 locus presented male-biased EGFP expression in the liver, and the expression was activated by testosterone during puberty. The integration of the pCAG-eGFP transgene altered the epigenetic regulation of the adjacent chromatin, including increased binding of STAT5b, a sexually dimorphic expression regulator, and the transformation of DNA methylation from hypermethylation into male-biased hypomethylation. Through this de novo sexually dimorphic expression of the transgene, the Akr1A1eGFP mouse provides a useful model to study the mechanisms and the dynamic changes of sexually dimorphic gene expression during either development or pathogenesis of the liver.
Collapse
|
6
|
Braun CMJ, Roberge C. Gender-related protection from or vulnerability to severe CNS diseases: gonado-structural and/or gonado-activational? A meta-analysis of relevant epidemiological studies. Int J Dev Neurosci 2014; 38:36-51. [PMID: 25109841 DOI: 10.1016/j.ijdevneu.2014.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 07/29/2014] [Accepted: 07/30/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND A vast scientific literature has dealt with gender-specific risk for brain disorder. That field is evolving toward a consensus to the effect that the estrogen hormone family is outstandingly and uniquely neuroprotective. However, the epidemiology relevant to this general outlook remains piecemeal. METHOD The present investigation strategically formats the relevant epidemiological findings around the world in order to quantitatively meta-analyze gender ratio of risk for a variety of relevant severe central nervous system (CNS) diseases at all three gonadal stages of the life cycle, pre pubertal, post adolescent/pre menopausal, and post menopausal. RESULTS The data quantitatively establish that (1) no single epidemiological study should be cited as evidence of gender-specific neuroprotection against the most common severe CNS diseases because the gender-specific risk ratios are contradictory from one study to the other; (2) risk for severe CNS disease is indeed significantly gender-specific, but either gender can be protected: it depends on the disease, not at all on the age bracket. CONCLUSION Our assay of gender-specific risk for severe brain disease around the world has not been able to support the idea according to which any one gender-prevalent gonadal steroid hormone dominates as a neuroprotective agent at natural concentrations.
Collapse
Affiliation(s)
- Claude M J Braun
- Department of Psychology, Université du Québec à Montréal, Canada.
| | - Carl Roberge
- Department of Psychology, Université du Québec à Montréal, Canada
| |
Collapse
|
7
|
Aberg KA, Xie LY, McClay JL, Nerella S, Vunck S, Snider S, Beardsley PM, van den Oord EJCG. Testing two models describing how methylome-wide studies in blood are informative for psychiatric conditions. Epigenomics 2013; 5:367-77. [PMID: 23895651 PMCID: PMC3904748 DOI: 10.2217/epi.13.36] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
AIM As the primary relevant tissue (brain) for psychiatric disorders is commonly not available, we aimed to investigate whether blood can be used as a proxy in methylation studies on the basis of two models. In the 'signature' model methylation-disease associations occur because a disease-causing factor affected methylation in the blood. In the 'mirror-site' model the methylation status in the blood is correlated with the corresponding disease-causing site in the brain. MATERIALS, METHODS & RESULTS: Methyl-binding domain enrichment and next-generation sequencing of the blood, cortex and hippocampus from four haloperidol-treated and ten untreated C57BL/6 mice revealed high levels of correlation in methylation across tissues. Despite the treatment inducing a large number of methylation changes, this correlation remains high. CONCLUSION Our results show that, consistent with the signature model, factors that affect brain processes (i.e., haloperidol) leave biomarker signatures in the blood and, consistent with the mirror-site model, the methylation status of many sites in the blood mirror those in the brain.
Collapse
Affiliation(s)
- Karolina A Aberg
- Center for Biomarker Research & Personalized Medicine, School of Pharmacy, Virginia Commonwealth University, 1112 East Clay Street, PO Box 980533, Richmond, VA 23298, USA.
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Takasugi M, Hayakawa K, Arai D, Shiota K. Age- and sex-dependent DNA hypomethylation controlled by growth hormone in mouse liver. Mech Ageing Dev 2013; 134:331-7. [PMID: 23707638 DOI: 10.1016/j.mad.2013.05.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/28/2013] [Accepted: 05/04/2013] [Indexed: 11/22/2022]
Abstract
In mammals, differences in liver function and aging have been observed between sexes; however, the epigenetic mechanisms underlying such differences remain largely unexplored. In this study, we investigated sex- and age-dependent DNA methylation status in the mouse liver. We analyzed 90 known sex-differentially expressed genes, and identified sex-dependent methylation in Zfp809, Hsd3b5, Treh, Cxcl11, Cyp17a1, and Nnmt genes. After 4 weeks of age, we noted the gradual establishment of sex-dependent hypomethylation in each of these genes in either males or females. The exposure of male mice to female-like growth hormone (GH) profile repressed male-predominant hypomethylation and promoted female-predominant hypomethylation. The occurrence of age-dependent hypomethylation, including at loci for which we also observed sex-dependent changes in DNA methylation, was accompanied by the downregulation of DNMT3A/B. In addition, we found that age-dependent hypomethylation was promoted through liver regeneration induced by partial hepatectomy, suggesting that DNMT activities were not enough to retain methylation levels. In conclusion, our results demonstrate that sex-dependent GH profiles influence the age-progressive hypomethylation under decreased DNMT3A/B levels in certain regions of the genome.
Collapse
Affiliation(s)
- Masaki Takasugi
- Laboratory of Cellular Biochemistry, Department of Animal Resource Science/Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | | | | | | |
Collapse
|
9
|
Aberg KA, McClay JL, Nerella S, Xie LY, Clark SL, Hudson AD, Bukszár J, Adkins D, Hultman CM, Sullivan PF, Magnusson PKE, van den Oord EJCG. MBD-seq as a cost-effective approach for methylome-wide association studies: demonstration in 1500 case--control samples. Epigenomics 2013; 4:605-21. [PMID: 23244307 DOI: 10.2217/epi.12.59] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
AIM We studied the use of methyl-CpG binding domain (MBD) protein-enriched genome sequencing (MBD-seq) as a cost-effective screening tool for methylome-wide association studies (MWAS). MATERIALS & METHODS Because MBD-seq has not yet been applied on a large scale, we first developed and tested a pipeline for data processing using 1500 schizophrenia cases and controls plus 75 technical replicates with an average of 68 million reads per sample. This involved the use of technical replicates to optimize quality control for multi- and duplicate-reads, an in silico experiment to identify CpGs in loci with alignment problems, CpG coverage calculations based on multiparametric estimates of the fragment size distribution, a two-stage adaptive algorithm to combine data from correlated adjacent CpG sites, principal component analyses to control for confounders and new software tailored to handle the large data set. RESULTS We replicated MWAS findings in independent samples using a different technology that provided single base resolution. In an MWAS of age-related methylation changes, one of our top findings was a previously reported robust association involving GRIA2. Our results also suggested that owing to the many confounding effects, a considerable challenge in MWAS is to identify those effects that are informative about disease processes. CONCLUSION This study showed the potential of MBD-seq as a cost-effective tool in large-scale disease studies.
Collapse
Affiliation(s)
- Karolina A Aberg
- Center for Biomarker Research & Personalized Medicine, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Aberg KA, Xie LY, Nerella S, Copeland WE, Costello EJ, van den Oord EJCG. High quality methylome-wide investigations through next-generation sequencing of DNA from a single archived dry blood spot. Epigenetics 2013; 8:542-7. [PMID: 23644822 PMCID: PMC3741224 DOI: 10.4161/epi.24508] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The potential importance of DNA methylation in the etiology of complex diseases has led to interest in the development of methylome-wide association studies (MWAS) aimed at interrogating all methylation sites in the human genome. When using blood as biomaterial for a MWAS the DNA is typically extracted directly from fresh or frozen whole blood that was collected via venous puncture. However, DNA extracted from dry blood spots may also be an alternative starting material. In the present study, we apply a methyl-CpG binding domain (MBD) protein enrichment-based technique in combination with next generation sequencing (MBD-seq) to assess the methylation status of the ~27 million CpGs in the human autosomal reference genome. We investigate eight methylomes using DNA from blood spots. This data are compared with 1,500 methylomes previously assayed with the same MBD-seq approach using DNA from whole blood. When investigating the sequence quality and the enrichment profile across biological features, we find that DNA extracted from blood spots gives comparable results with DNA extracted from whole blood. Only if the amount of starting material is ≤ 0.5µg DNA we observe a slight decrease in the assay performance. In conclusion, we show that high quality methylome-wide investigations using MBD-seq can be conducted in DNA extracted from archived dry blood spots without sacrificing quality and without bias in enrichment profile as long as the amount of starting material is sufficient. In general, the amount of DNA extracted from a single blood spot is sufficient for methylome-wide investigations with the MBD-seq approach.
Collapse
Affiliation(s)
- Karolina A Aberg
- Center for Biomarker Research and Personalized Medicine, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA.
| | | | | | | | | | | |
Collapse
|
11
|
Chen W, Gao G, Nerella S, Hultman CM, Magnusson PKE, Sullivan PF, Aberg KA, van den Oord EJCG. MethylPCA: a toolkit to control for confounders in methylome-wide association studies. BMC Bioinformatics 2013; 14:74. [PMID: 23452721 PMCID: PMC3599654 DOI: 10.1186/1471-2105-14-74] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 02/20/2013] [Indexed: 12/15/2022] Open
Abstract
Background In methylome-wide association studies (MWAS) there are many possible differences between cases and controls (e.g. related to life style, diet, and medication use) that may affect the methylome and produce false positive findings. An effective approach to control for these confounders is to first capture the major sources of variation in the methylation data and then regress out these components in the association analyses. This approach is, however, computationally very challenging due to the extremely large number of methylation sites in the human genome. Result We introduce MethylPCA that is specifically designed to control for potential confounders in studies where the number of methylation sites is extremely large. MethylPCA offers a complete and flexible data analysis including 1) an adaptive method that performs data reduction prior to PCA by empirically combining methylation data of neighboring sites, 2) an efficient algorithm that performs a principal component analysis (PCA) on the ultra high-dimensional data matrix, and 3) association tests. To accomplish this MethylPCA allows for parallel execution of tasks, uses C++ for CPU and I/O intensive calculations, and stores intermediate results to avoid computing the same statistics multiple times or keeping results in memory. Through simulations and an analysis of a real whole methylome MBD-seq study of 1,500 subjects we show that MethylPCA effectively controls for potential confounders. Conclusions MethylPCA provides users a convenient tool to perform MWAS. The software effectively handles the challenge in memory and speed to perform tasks that would be impossible to accomplish using existing software when millions of sites are interrogated with the sample sizes required for MWAS.
Collapse
Affiliation(s)
- Wenan Chen
- Department of Biostatistics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
van den Oord EJCG, Bukszar J, Rudolf G, Nerella S, McClay JL, Xie LY, Aberg KA. Estimation of CpG coverage in whole methylome next-generation sequencing studies. BMC Bioinformatics 2013; 14:50. [PMID: 23398781 PMCID: PMC3599116 DOI: 10.1186/1471-2105-14-50] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 02/08/2013] [Indexed: 01/28/2023] Open
Abstract
Background Methylation studies are a promising complement to genetic studies of DNA sequence. However, detailed prior biological knowledge is typically lacking, so methylome-wide association studies (MWAS) will be critical to detect disease relevant sites. A cost-effective approach involves the next-generation sequencing (NGS) of single-end libraries created from samples that are enriched for methylated DNA fragments. A limitation of single-end libraries is that the fragment size distribution is not observed. This hampers several aspects of the data analysis such as the calculation of enrichment measures that are based on the number of fragments covering the CpGs. Results We developed a non-parametric method that uses isolated CpGs to estimate sample-specific fragment size distributions from the empirical sequencing data. Through simulations we show that our method is highly accurate. While the traditional (extended) read count methods resulted in severely biased coverage estimates and introduces artificial inter-individual differences, through the use of the estimated fragment size distributions we could remove these biases almost entirely. Furthermore, we found correlations of 0.999 between coverage estimates obtained using fragment size distributions that were estimated with our method versus those that were “observed” in paired-end sequencing data. Conclusions We propose a non-parametric method for estimating fragment size distributions that is highly precise and can improve the analysis of cost-effective MWAS studies that sequence single-end libraries created from samples that are enriched for methylated DNA fragments.
Collapse
Affiliation(s)
- Edwin J C G van den Oord
- Center for Biomarker Research and Personalized Medicine, School of Pharmacy, Virginia Commonwealth University, 1112 East Clay Street, P.O. Box 980533, Richmond, VA 23298, USA.
| | | | | | | | | | | | | |
Collapse
|
13
|
The KRAB zinc finger protein RSL1 regulates sex- and tissue-specific promoter methylation and dynamic hormone-responsive chromatin configuration. Mol Cell Biol 2012; 32:3732-42. [PMID: 22801370 DOI: 10.1128/mcb.00615-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Over 400 Krüppel-associated box zinc finger proteins (KRAB-ZFPs) are encoded in mammalian genomes. While KRAB-ZFPs strongly repress transcription in vitro, little is known about their biological function or gene targets in vivo. Regulator of sex limitation 1 (Rsl1), one of the first KRAB-Zfp genes assigned a physiological role, accentuates sex-biased liver gene expression, most dramatically for mouse sex-limited protein (Slp), which provides an in vivo reporter of KRAB-ZFP function. Slp is induced in males in the liver and kidney by growth hormone (GH) and androgen, respectively. In the liver but not kidney, the Rsl1 genotype correlates with methylation of a CpG dinucleotide in the Slp promoter that is demethylated at puberty. RSL1 binds 2 kb upstream of the Slp promoter, both in vitro and in vivo, within an enhancer containing response elements for STAT5b. Chromatin immunoprecipitation (ChIP) assays demonstrate that RSL1 recruits KAP1/TRIM28, the corepressor for KRAB action in vitro, to this enhancer. Slp induction requires rapid cycling of STAT5b in chromatin. Remarkably, RSL1 simultaneously binds adjacent to STAT5b with a reciprocal binding pattern that limits hormonal response. These experiments demonstrate a surprisingly dynamic interplay between a hormonal activator, STAT5b, and a KRAB-ZFP repressor and provide unique insights into KRAB-ZFP epigenetic mechanisms.
Collapse
|
14
|
Campbell IC, Mill J, Uher R, Schmidt U. Eating disorders, gene-environment interactions and epigenetics. Neurosci Biobehav Rev 2010; 35:784-93. [PMID: 20888360 DOI: 10.1016/j.neubiorev.2010.09.012] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 08/06/2010] [Accepted: 09/22/2010] [Indexed: 12/15/2022]
Abstract
This review describes the various subtypes of eating disorders and examines factors associated with the risk of illness. It considers evidence that the development and maintenance of eating disorders is due to gene-environment interactions (GxE) that alter genetic expression via epigenetic processes. It describes how environmental factors such as those associated with nutrition and/or stress may cause epigenetic changes which have transcriptional and phenotypic effects, which, in turn, alter the long term risk of developing an eating disorder. It reviews theoretical and practical issues associated with epigenetic studies in psychiatry and how these are relevant to eating disorders. It examines the limited number of epigenetic studies which have been conducted in eating disorders and suggests directions for further research. Understanding the relationship between epigenetic processes and the risk of an eating disorder opens possibilities for preventive and/or therapeutic interventions. For example, epigenetic changes associated with diet and weight may be reversible and those associated with cognitive processes may be accessible to pharmacological interventions.
Collapse
Affiliation(s)
- Iain C Campbell
- Section of Eating Disorders, King's College London, Institute of Psychiatry, London SE5 8AF, UK.
| | | | | | | |
Collapse
|
15
|
Pidsley R, Dempster EL, Mill J. Brain weight in males is correlated with DNA methylation at IGF2. Mol Psychiatry 2010; 15:880-1. [PMID: 20010889 DOI: 10.1038/mp.2009.138] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
16
|
Leuenberger N, Pradervand S, Wahli W. Sumoylated PPARalpha mediates sex-specific gene repression and protects the liver from estrogen-induced toxicity in mice. J Clin Invest 2010; 119:3138-48. [PMID: 19729835 DOI: 10.1172/jci39019] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 07/01/2009] [Indexed: 12/28/2022] Open
Abstract
As most metabolic studies are conducted in male animals, understanding the sex specificity of the underlying molecular pathways has been broadly neglected; for example, whether PPARs elicit sex-dependent responses has not been determined. Here we show that in mice, PPARalpha has broad female-dependent repressive actions on hepatic genes involved in steroid metabolism and immunity. In male mice, this effect was reproduced by the administration of a synthetic PPARalpha ligand. Using the steroid oxysterol 7alpha-hydroxylase cytochrome P4507b1 (Cyp7b1) gene as a model, we elucidated the molecular mechanism of this sex-specific PPARalpha-dependent repression. Initial sumoylation of the ligand-binding domain of PPARalpha triggered the interaction of PPARalpha with GA-binding protein alpha (GABPalpha) bound to the target Cyp7b1 promoter. Histone deacetylase and DNA and histone methylases were then recruited, and the adjacent Sp1-binding site and histones were methylated. These events resulted in loss of Sp1-stimulated expression and thus downregulation of Cyp7b1. Physiologically, this repression conferred on female mice protection against estrogen-induced intrahepatic cholestasis, the most common hepatic disease during pregnancy, suggesting a therapeutic target for prevention of this disease.
Collapse
Affiliation(s)
- Nicolas Leuenberger
- Center for Integrative Genomics, National Research Center "Frontiers in Genetics," Switzerland
| | | | | |
Collapse
|
17
|
Sakai N, Sakamoto KQ, Fujita S, Ishizuka M. The importance of heterogeneous nuclear ribonucleoprotein K on cytochrome P450 2D2 gene regulation: its binding is reduced in Dark Agouti rats. Drug Metab Dispos 2009; 37:1703-10. [PMID: 19420131 DOI: 10.1124/dmd.109.027284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Cytochrome P450 (P450) 2D2 (CYP2D2) enzyme is known to metabolize the majority of typical substrates of the human CYP2D6 enzyme, which is the most extensively characterized polymorphic drug-metabolizing enzyme. Despite its impact on drug metabolism in rats, the transcriptional regulation of CYP2D2 remains to be elucidated. We clarified the molecular mechanism of CYP2D2 gene expression. The CYP2D2 gene was positively regulated by the poly(C)-binding protein heterogeneous nuclear ribonucleoprotein K (hnRNP K) through a transcriptional regulatory element located in the 5'-flanking region from -94 to -113. To date, nothing is known about the potential role of hnRNP K in P450 gene regulation. Thus, this is the first report that hnRNP K protein is involved in CYP2D2 gene regulation. Furthermore, we elucidated the genetic basis of the extremely low expression of CYP2D2 mRNA in Dark Agouti (DA) rats. Because of its relatively low abundance, DA rats have been frequently used for the study of CYP2D substrate metabolism as the animal model of the poor metabolizer phenotype for CYP2D6 compared with Sprague-Dawley rats as an extensive metabolizer phenotype. We found a single substitution within the transcriptional regulatory element of the CYP2D2 gene in DA rats. The mutation was detected in the polypyrimidine sequence that is the preferred binding site for hnRNP K protein. The mutation within the transcriptional regulatory element attenuated the binding of hnRNP K protein. In conclusion, decreased recruitment of hnRNP K protein to the mutated sequence causes the low expression of CYP2D2 mRNA in DA rats.
Collapse
Affiliation(s)
- Noriaki Sakai
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | | | | | | |
Collapse
|
18
|
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is among the most common childhood-onset psychiatric disorders. Although family, twin, and adoption studies demonstrate that ADHD is a highly heritable condition, studies also suggest that genetic architecture is complex, prompting the use of more advanced methodologies such as genome-wide linkage and association studies. Although such studies are theoretically compelling, replication of these results has been inconsistent. Meta-analyses have produced more reliable results, but the associations identified to date account for only a small percentage of the genetic component of ADHD. Approaches such as neuroimaging genetics and epigenetic studies are being explored to probe further the etiologic complexity of this disorder.
Collapse
|
19
|
Mill J, Petronis A. Pre- and peri-natal environmental risks for attention-deficit hyperactivity disorder (ADHD): the potential role of epigenetic processes in mediating susceptibility. J Child Psychol Psychiatry 2008; 49:1020-30. [PMID: 18492038 DOI: 10.1111/j.1469-7610.2008.01909.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is a common childhood neurobehavioural disorder defined by symptoms of developmentally inappropriate inattention, impulsivity and hyperactivity. As is the norm for most psychiatric phenotypes, traditional aetiological studies have focused primarily on the interplay between genetic and environmental factors. It is likely that epigenetic factors, i.e., heritable, but reversible changes to genomic function that are independent of DNA sequence, are also important. It is known that epigenetic processes can be induced following exposure to a range of external factors, and thus provide a mechanism by which the environment can lead to long-term alterations in phenotype. In this article we hypothesise that epigenetic dysregulation may mediate the association observed between early-development environmental insults and ADHD. We propose that understanding the epigenetic processes involved in linking specific environmental pathogens to an increased risk for ADHD may offer new possibilities for preventative and therapeutic intervention.
Collapse
Affiliation(s)
- Jonathan Mill
- Institute of Psychiatry, SGDP Research Centre, London, UK.
| | | |
Collapse
|
20
|
Abstract
There is accumulating evidence for nongenetic transgenerational inheritance with conspicuous marked sexual dimorphism for both the modes of transmission and the effects. Given the critical spatiotemporal windows, the role of the sex chromosomes, the regulatory pathways underlying sexual differentiation during gonad and brain development, and other developmental processes, as well as the lifelong impact of sex hormones, it is not surprising that most of the common diseases, which often take root in early development, display some degree of sex bias. The flexibility of epigenetic marks may make it possible for environmental and nutritional factors, or endocrine disruptors to alter-during a particular spatiotemporal window in a sex-specific manner-the sex-specific methylation or demethylation of specific CpGs and histone/chromatin modifications underlying sex-specific expression of a substantial proportion of genes. Thus, finely tuned developmental program aspects, specific to one sex, may be more sensitive to specific environmental challenges, particularly during developmental programming and gametogenesis, but also throughout the individual's life under the influence of sex steroid hormones. This review highlights the importance of studying both sexes in epidemiologic protocols or dietary interventions both in humans and in experimental models in animals.
Collapse
Affiliation(s)
- Alexandre Vigé
- Inserm U781 Genetics and Epigenetics of Metabolic Diseases, Neurosensorial Diseases and Development, Hôpital Necker-Enfants Malades, Université Paris Deseartes, Paris, France
| | | | | |
Collapse
|
21
|
Bromberg A, Levine J, Nemetz B, Belmaker RH, Agam G. No association between global leukocyte DNA methylation and homocysteine levels in schizophrenia patients. Schizophr Res 2008; 101:50-7. [PMID: 18276118 DOI: 10.1016/j.schres.2008.01.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 12/30/2007] [Accepted: 01/04/2008] [Indexed: 12/11/2022]
Abstract
Meta-analysis recently suggested that a 5 muM increase in homocysteine is associated with a 70% higher risk for schizophrenia. Elevated homocysteine is reported to alter macromolecule methylation. We studied whether elevated plasma homocysteine levels in schizophrenia are associated with altered leukocyte global DNA methylation. DNA was extracted from peripheral blood leukocytes of 28 schizophrenia patients vs. 26 matched healthy controls. Percent of global genome DNA methylation was measured using the cytosine-extension method. Homocysteine levels were higher in schizophrenia patients than in controls. No difference in global DNA methylation between schizophrenia patients and control subjects was found (74.0%+/-14.8 vs. 69.4+/-22.0, p=0.31). A significant interaction between diagnosis and smoking on DNA methylation was obtained (F=6.8, df=1,47, p=0.032). Although leukocytes may be a useful cell model to evaluate epigenetic changes such as global DNA methylation in brain, future studies should compare global DNA methylation in peripheral tissue vs. brain in laboratory animals.
Collapse
Affiliation(s)
- A Bromberg
- Faculty of Health Sciences, Stanley Research Center, Ben-Gurion University of the Negev & Beersheva Mental Health Center, Beersheva, Israel
| | | | | | | | | |
Collapse
|
22
|
Mill J, Tang T, Kaminsky Z, Khare T, Yazdanpanah S, Bouchard L, Jia P, Assadzadeh A, Flanagan J, Schumacher A, Wang SC, Petronis A. Epigenomic profiling reveals DNA-methylation changes associated with major psychosis. Am J Hum Genet 2008; 82:696-711. [PMID: 18319075 DOI: 10.1016/j.ajhg.2008.01.008] [Citation(s) in RCA: 553] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 11/12/2007] [Accepted: 01/04/2008] [Indexed: 10/22/2022] Open
Abstract
Epigenetic misregulation is consistent with various non-Mendelian features of schizophrenia and bipolar disorder. To date, however, few studies have investigated the role of DNA methylation in major psychosis, and none have taken a genome-wide epigenomic approach. In this study we used CpG-island microarrays to identify DNA-methylation changes in the frontal cortex and germline associated with schizophrenia and bipolar disorder. In the frontal cortex we find evidence for psychosis-associated DNA-methylation differences in numerous loci, including several involved in glutamatergic and GABAergic neurotransmission, brain development, and other processes functionally linked to disease etiology. DNA-methylation changes in a significant proportion of these loci correspond to reported changes of steady-state mRNA level associated with psychosis. Gene-ontology analysis highlighted epigenetic disruption to loci involved in mitochondrial function, brain development, and stress response. Methylome network analysis uncovered decreased epigenetic modularity in both the brain and the germline of affected individuals, suggesting that systemic epigenetic dysfunction may be associated with major psychosis. We also report evidence for a strong correlation between DNA methylation in the MEK1 gene promoter region and lifetime antipsychotic use in schizophrenia patients. Finally, we observe that frontal-cortex DNA methylation in the BDNF gene is correlated with genotype at a nearby nonsynonymous SNP that has been previously associated with major psychosis. Our data are consistent with the epigenetic theory of major psychosis and suggest that DNA-methylation changes are important to the etiology of schizophrenia and bipolar disorder.
Collapse
|
23
|
Abstract
The purpose of this paper was to selectively review the literature on the role of epigenetics in mental illnesses. Aberrant epigenetic regulation has been clearly implicated in the aetiology of some human illnesses. In recent years a growing body of evidence has highlighted the possibility that epigenetics may also play a key role in the origins and expression of mental disorders. Epigenetic phenomena may help explain some of the complexity of mental illnesses and provide a basis for discovering novel pharmacological targets to treat these disorders.
Collapse
|
24
|
Abstract
Major depressive disorder (MDD) is a common and highly heterogeneous psychiatric disorder encompassing a spectrum of symptoms involving deficits to a range of cognitive, psychomotor and emotional processes. As is the norm for aetiological studies into the majority of psychiatric phenotypes, particular focus has fallen on the interplay between genetic and environmental factors. There are, however, several epidemiological, clinical and molecular peculiarities associated with MDD that are hard to explain using traditional gene- and environment-based approaches. Our goal in this study is to demonstrate the benefits of looking beyond conventional 'DNA+environment' and 'DNA x environment' aetiological paradigms. Epigenetic factors - inherited and acquired modifications of DNA and histones that regulate various genomic functions occurring without a change in nuclear DNA sequence - offer new insights about many of the non-Mendelian features of major depression, and provide a direct mechanistic route via which the environment can interact with the genome. The study of epigenetics, especially in complex diseases, is a relatively new field of research, and optimal laboratory techniques and analysis methods are still being developed. Incorporating epigenetic research into aetiological studies of MDD thus presents a number of methodological and interpretive challenges that need to be addressed. Despite these difficulties, the study of DNA methylation and histone modifications has the potential to transform our understanding about the molecular aetiology of complex diseases.
Collapse
Affiliation(s)
- J Mill
- The Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | | |
Collapse
|
25
|
Schumacher A, Petronis A. Epigenetics of Complex Diseases: From General Theory to Laboratory Experiments. Curr Top Microbiol Immunol 2006; 310:81-115. [PMID: 16909908 DOI: 10.1007/3-540-31181-5_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Despite significant effort, understanding the causes and mechanisms of complex non-Mendelian diseases remains a key challenge. Although numerous molecular genetic linkage and association studies have been conducted in order to explain the heritable predisposition to complex diseases, the resulting data are quite often inconsistent and even controversial. In a similar way, identification of environmental factors causal to a disease is difficult. In this article, a new interpretation of the paradigm of "genes plus environment" is presented in which the emphasis is shifted to epigenetic misregulation as a major etiopathogenic factor. Epigenetic mechanisms are consistent with various non-Mendelian irregularities of complex diseases, such as the existence of clinically indistinguishable sporadic and familial cases, sexual dimorphism, relatively late age of onset and peaks of susceptibility to some diseases, discordance of monozygotic twins and major fluctuations on the course of disease severity. It is also suggested that a substantial portion of phenotypic variance that traditionally has been attributed to environmental effects may result from stochastic epigenetic events in the cell. It is argued that epigenetic strategies, when applied in parallel with the traditional genetic ones, may significantly advance the discovery of etiopathogenic mechanisms of complex diseases. The second part of this chapter is dedicated to a review of laboratory methods for DNA methylation analysis, which may be useful in the study of complex diseases. In this context, epigenetic microarray technologies are emphasized, as it is evident that such technologies will significantly advance epigenetic analyses in complex diseases.
Collapse
Affiliation(s)
- A Schumacher
- The Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, ON, Toronto, Canada
| | | |
Collapse
|
26
|
Abstract
The liver is a primary target for the action of GH, a pituitary protein hormone that regulates a broad range of physiological processes, including long bone growth, fatty acid oxidation, glucose uptake, and hepatic steroid and foreign compound metabolism. GH exerts sex-dependent effects on the liver in many species, with many hepatic genes, most notably genes coding for cytochrome P450 (CYP) enzymes, being transcribed in a sex-dependent manner. Sex differences in CYP expression are most striking in rats and mice (up to 500-fold male-female differences), but are also seen, albeit to a much smaller degree, in humans, where they are an important determinant of the sex dependence of hepatic drug and steroid metabolism. This article examines the mechanisms whereby GH, via its sex-dependent temporal patterns of pituitary release, activates intracellular signaling leading to the sexually dimorphic transcription of CYPs and other liver-expressed genes. Recent findings implicating the GH-regulated transcription factor STAT5b (signal transducer and activator of transcription 5b), hepatocyte nuclear factors 3beta, 4alpha and 6, and sex differences in DNA methylation and chromatin structure in the sex-dependent actions of GH are reviewed, and current mechanistic models are evaluated.
Collapse
Affiliation(s)
- David J Waxman
- Department of Biology, Boston University, 5 Cummington Street, Boston, Massachusetts 02215, USA.
| | | |
Collapse
|
27
|
Abstract
Gender differences in susceptibility to complex disease such as asthma, diabetes, lupus, autism and major depression, among numerous other disorders, represent one of the hallmarks of non-Mendelian biology. It has been generally accepted that endocrinological differences are involved in the sexual dimorphism of complex disease; however, specific molecular mechanisms of such hormonal effects have not been elucidated yet. This paper will review evidence that sex hormone action may be mediated via gene-specific epigenetic modifications of DNA and histones. The epigenetic modifications can explain sex effects at DNA sequence polymorphisms and haplotypes identified in gender-stratified genetic linkage and association studies. Hormone-induced DNA methylation and histone modification changes at specific gene regulatory regions may increase or reduce the risk of a disease. The epigenetic interpretation of sexual dimorphism fits well into the epigenetic theory of complex disease, which argues for the primary pathogenic role of inherited and/or acquired epigenetic misregulation rather than DNA sequence variation. The new experimental strategies, especially the high throughput microarray-based epigenetic profiling, can be used for testing the epigenetic hypothesis of gender effects in complex diseases.
Collapse
Affiliation(s)
- Zachary Kaminsky
- The Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, Toronto, Canada
| | | | | |
Collapse
|
28
|
Waxman DJ, Celenza JL. Sexual dimorphism of hepatic gene expression: novel biological role of KRAB zinc finger repressors revealed. Genes Dev 2003; 17:2607-13. [PMID: 14597659 DOI: 10.1101/gad.1154603] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- David J Waxman
- Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, Massachusetts 02215, USA
| | | |
Collapse
|
29
|
Nakamura A, Okazaki Y, Sugimoto J, Oda T, Jinno Y. Human endogenous retroviruses with transcriptional potential in the brain. J Hum Genet 2003; 48:575-81. [PMID: 14564540 DOI: 10.1007/s10038-003-0081-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2003] [Accepted: 09/05/2003] [Indexed: 12/23/2022]
Abstract
Genetic studies of neuropsychiatric disorders have often produced conflicting results, which might partly result from the involvement of epigenetic modifications. We intended to explore the possible implication of DNA methylation and human endogenous retroviruses (HERVs) in neuropsychiatric disorders. In the present study, we identified two HERV loci that are expected to retain the transcriptional activity in the brain. One was located on chromosome 1q21-q22 and the other on 22q12. Interestingly, these regions were overlapped with or included in those of schizophrenia-susceptible loci, SCZD9 and SCZD4, respectively. Particularly, the HERV on 22q12 was located in the opposite direction 4 kb downstream of the Synapsin III gene. These HERV loci could afford clear targets for methylation and expression analyses in postmortem brains of patients with psychiatric disorders such as schizophrenia. In addition, we confirmed our previous finding that only a few of particular HERV-K loci were activated among a number of highly homologous loci in teratocarcinoma cell lines. These activated loci included ones common to all teratocarcinoma cell lines analyzed and depending on their male or female origin.
Collapse
Affiliation(s)
- Akifumi Nakamura
- Department of Molecular Biology, Ryukyu University School of Medicine, 207 Nishihara, Okinawa 903-0215, Japan
| | | | | | | | | |
Collapse
|
30
|
Mizuno D, Takahashi Y, Hiroi T, Imaoka S, Kamataki T, Funae Y. A novel transcriptional element which regulates expression of the CYP2D4 gene by Oct-1 and YY-1 binding. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1627:121-8. [PMID: 12818430 DOI: 10.1016/s0167-4781(03)00085-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We first identified the transcriptional regulatory element of the CYP2D4 gene. CYP2D4 is of interest in brain pharmacology and physiology because this enzyme can be involved in the metabolism of endogenous and exogenous compounds, which act on the central nervous system. Transfection studies using a series of the CYP2D4 promoter luciferase constructs identified the transcriptional element of CYP2D4 in the sequence between nucleotides -116 and -90 (named the neural expression regulatory element, NERE). The nucleotide sequence of NERE was specific for the CYP2D4 gene. Within this region, two nuclear factor-binding sequences, Oct-1 and YY-1, were present. Oct-1 acts as the activator of the CYP2D4. The core sequence of the YY-1 binding motif partially overlapped that of the Oct-1 binding motif. YY-1 may act as the repressor of CYP2D4, which interferes with Oct-1 activation by its binding to NERE. We concluded that a novel transcriptional regulatory element NERE specifically regulates the expression of the CYP2D4. This regulation system may be involved in the unique distribution of this isoform, such as the expression in the brain.
Collapse
Affiliation(s)
- Dai Mizuno
- Department of Chemical Biology, Osaka City University Medical School, 1-4-3, Asahimachi, Abeno-ku, Osaka 545-8585, Japan
| | | | | | | | | | | |
Collapse
|
31
|
Tullis KM, Krebs CJ, Leung JYM, Robins DM. The regulator of sex-limitation gene, rsl, enforces male-specific liver gene expression by negative regulation. Endocrinology 2003; 144:1854-60. [PMID: 12697692 DOI: 10.1210/en.2002-0190] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Expression of a broad array of proteins is sexually dimorphic in rodent liver, dependent on sex-specific patterns of GH secretion. Mice carrying rsl (regulator of sex limitation) alleles, discovered as trans-acting loci affecting the mouse sex-limited protein (Slp) gene, reveal an additional axis in male-specific gene regulation. Slp expresses in adult males, but in rsl homozygous mice, Slp is also expressed in females. In this study, we examined congenic rsl strains to determine rsl's site of action, breadth of targets, and interaction with hormonal induction. We show that rsl affects Slp in liver, but not kidney, and that Rsl acts on a spectrum of male-specific liver genes, including mouse urinary proteins and a cytochrome P450 expressed predominantly by males, Cyp 2d-9, but does not act on the female-prominent P450, Cyp 2a-4. Slp expression in hypophysectomized or Tfm/Y rsl mice reveals that Rsl action is independent of GH or androgen signaling. Further, parabiosis of Rsl and rsl mice does not alter expression patterns, consistent with rsl action being liver intrinsic. Finally, Slp expression initiates earlier in rsl mice, suggesting that Rsl operates before, as well as independently of, hormonal induction. This characterization suggests Rsl functions to repress transcription of a set of genes that have in common their hormonal induction in male liver, and thus accentuates sexual dimorphism of liver gene expression.
Collapse
Affiliation(s)
- Kathryn M Tullis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan 48109-0618, USA
| | | | | | | |
Collapse
|
32
|
Kato C, Petronis A, Okazaki Y, Tochigi M, Umekage T, Sasaki T. Molecular genetic studies of schizophrenia: challenges and insights. Neurosci Res 2002; 43:295-304. [PMID: 12135773 DOI: 10.1016/s0168-0102(02)00064-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Schizophrenia (SCZ) is a mental disease that affects approximately 1% of the population with life-long devastating consequences. Based on evidence for a major contribution of genetic factors, a decade of extensive efforts has been dedicated to the search of DNA sequence variations that increase the risk to SCZ. Search for genes in rare multiplex SCZ families with a large number of affected individuals and quasi-Mendelian mode of inheritance using genetic linkage methodology has been one of the favorite strategies in psychiatric genetics. Although several genomic regions were suggested for linkage to SCZ, not a single gene causing or predisposing to SCZ has been identified thus far. Furthermore, it is not clear whether the genes of familial SCZ are also involved in sporadic cases that represent the overwhelming majority of SCZ patients. For sporadic cases, genetic association studies comparing the distribution of allelic frequencies of candidate genes in SCZ patients and controls have been performed but the outcome of such studies has also been quite modest. Several factors such as possible involvement of numerous interactive genes of minor effect, yet unknown environmental effects and diagnostic ambiguities of the disease have made genetic studies in SCZ quite unproductive. In terms of future studies, a genome-wide association search is a promising approach; however, this approach requires genotyping of thousands of genetic markers in large samples. In addition, a detailed analysis of the genes, expression of which changes under the influence of environmental factors, can indicate good candidates for genetic association studies. In this connection, investigations of the epigenetic regulation of genes and not only the DNA sequence variation, may be necessary for complete understanding of the etiopathogenic mechanisms of SCZ.
Collapse
Affiliation(s)
- Chieko Kato
- Department of Neuropsychiatry, University of Tokyo, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
33
|
Li S, Ma L, Chiang T, Burow M, Newbold RR, Negishi M, Barrett JC, McLachlan JA. Promoter CpG methylation of Hox-a10 and Hox-a11 in mouse uterus not altered upon neonatal diethylstilbestrol exposure. Mol Carcinog 2001; 32:213-9. [PMID: 11746833 DOI: 10.1002/mc.10015] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mouse abdominal B-like Hoxa genes are expressed and functionally required in the developing reproductive tracts. Mice lacking either Hoxa-10 or Hoxa-11, two of the AbdB Hoxa genes, exhibit abnormal uterine development similar to that induced by in utero diethylstilbestrol (DES) exposure. Indeed, uterine Hoxa-10 and Hoxa-11 expression is potently repressed by perinatal DES exposure, providing a potential molecular mechanism for DES-induced reproductive tract malformations. We have shown previously that DES can permanently alter uterine lactoferrin gene expression through modulation of the lactoferrin promoter methylation pattern. Here we ask whether a similar mechanism also functions to deregulate uterine Hoxa-10 or Hoxa-11 expression during neonatal DES exposure. We mapped the Hoxa-10 promoter by cloning a 1.485 kb DNA fragment 5' of the Hoxa-10 exon1a. A 5' rapid amplification of cDNA ends (RACE) experiment revealed a transcription start site for the a10-1 transcript. Functional analysis of the proximal 200-bp sequences demonstrated significant promoter activity, confirming the location of the Hoxa-10 promoter. Moreover, methylation assays performed on eight CpGs in Hoxa-10 and 19 CpGs in Hoxa-11 proximal promoters demonstrated that all these CpGs were highly unmethylated in both control and DES-dosed mice from postnatal day 5 to day 30. Significant methylation around Hoxa-10 and Hoxa-11 promoters was only observed in DES-induced uterine carcinomas in 18-mo-old mice. Our results suggest that DES-induced downregulations of Hoxa-10 or Hoxa-11 gene expression are not associated with methylation changes in their proximal promoters and that gene imprinting by developmental DES exposure may be a gene-specific phenomenon.
Collapse
Affiliation(s)
- S Li
- Laboratory of Biosystems and Cancer, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Abstract
The term "endocrine disrupting chemicals" is commonly used to describe environmental agents that alter the endocrine system. Laboratories working in this emerging field-environmental endocrine research-have looked at chemicals that mimic or block endogenous vertebrate steroid hormones by interacting with the hormone's receptor. Environmental chemicals known to do this do so most often with receptors derived from the steroid/thyroid/retinoid gene family. They include ubiquitous and persistent organochlorines, as well as plasticizers, pharmaceuticals, and natural hormones. These chemicals function as estrogens, antiestrogens, and antiandrogens but have few, if any, structural similarities. Therefore, receptor-based or functional assays have the best chance of detecting putative biological activity of environmental chemicals. Three nuclear estrogen receptor forms-alpha, beta, and gamma-as well as multiple membrane forms and a possible mitochondrial form have been reported, suggesting a previously unknown diversity of signaling pathways available to estrogenic chemicals. Examples of environmental or ambient estrogenization occur in laboratory experiments, zoo animals, domestic animals, wildlife, and humans. Environmentally estrogenized phenotypes may differ depending upon the time of exposure-i.e., whether the exposure occurred at a developmental (organizational and irreversible) or postdevelopmental (activational and reversible) stage. The term "estrogen" must be defined in each case, since steroidal estrogens differ among themselves and from synthetic or plant-derived chemicals. An "estrogen-like function" seems to be an evolutionarily ancient signal that has been retained in a number of chemicals, some of which are vertebrate hormones. Signaling, required for symbiosis between plants and bacteria, may be viewed, therefore, as an early example of hormone cross-talk. Developmental feminization at the structural or functional level is an emerging theme in species exposed, during embryonic or fetal life, to estrogenic compounds. Human experience as well as studies in experimental animals with the potent estrogen diethylstilbestrol provide informative models. Advances in the molecular genetics of sex differentiation in vertebrates facilitate mechanistic understanding. Experiments addressing the concept of gene imprinting or induction of epigenetic memory by estrogen or other hormones suggest a link to persistent, heritable phenotypic changes seen after developmental estrogenization, independent of mutagenesis. Environmental endocrine science provides a new context in which to examine the informational content of ecosystem-wide communication networks. As common features come to light, this research may allow us to predict environmentally induced alterations in internal signaling systems of vertebrates and some invertebrates and eventually to explicate environmental contributions to human reproductive and developmental health.
Collapse
Affiliation(s)
- J A McLachlan
- Department of Pharmacology, Tulane University Health Sciences Center, Environmental Endocrinology Laboratory, Center for Bioenvironmental Research, Tulane and Xavier Universities, New Orleans, Louisiana 70112-2699, USA.
| |
Collapse
|
35
|
McLachlan JA, Burow M, Chiang TC, Li SF. Gene imprinting in developmental toxicology: a possible interface between physiology and pathology. Toxicol Lett 2001; 120:161-4. [PMID: 11323173 DOI: 10.1016/s0378-4274(01)00295-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Gene imprinting is an epigenetic mechanism for accomplishing persistent change in gene expression. In this brief paper, we explore the mechanisms for imprinting genes and present data showing that the synthetic estrogen, diethylstilbestrol (DES) can developmentally imprint genes by changing the pattern of DNA methylation. We further discuss the implications of this and other findings for non-mutagenic aspects of developmental toxicology, and suggest ways to use this concept in modifying in vitro screening for developmental toxicants.
Collapse
Affiliation(s)
- J A McLachlan
- Environmental Endocrinology Laboratory, Center for Bioenvironmental Research, Tulane and Xavier Universities, 1340 Tulane Avenue, New Orleans, LA 70112, USA.
| | | | | | | |
Collapse
|
36
|
Abstract
Identification of genes predisposing their carrier to complex diseases is a much more complicated task than finding genes involved in simple mendelian diseases. The slow progress in the genetic research of complex diseases could be due to limitations in the basic research strategy, which is almost exclusively orientated to the detection of disease-related DNA mutations or polymorphisms. I argue in this article that epigenetic misregulation of genes is more consistent with the features of complex diseases than is DNA sequence variation, and therefore that epigenetic factors could be important in understanding the origins of complex diseases.
Collapse
Affiliation(s)
- A Petronis
- Neurogenetics Section Rm28, Centre for Addiction and Mental Health, 250 College Street, Ontario, Toronto, Canada M5T 1R8.
| |
Collapse
|
37
|
Yokomori N, Tawata M, Saito T, Shimura H, Onaya T. Regulation of the rat thyrotropin receptor gene by the methylation-sensitive transcription factor GA-binding protein. Mol Endocrinol 1998; 12:1241-9. [PMID: 9717849 DOI: 10.1210/mend.12.8.0142] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The GA-binding protein (GABP), a transcription factor with a widespread tissue distribution, consists of two subunits, a and beta1, and acts as a potent positive regulator of various genes. The effect of GABP on transcription of the TSH receptor (TSHR) gene in rat FRTL-5 thyroid cells has now been investigated. Both deoxyribonuclease I footprint analysis and gel mobility-shift assays indicated that bacterially expressed glutathione S-transferase fusion proteins of GABP subunits bind to a region spanning nucleotides (nt) -116 to -80 of the TSHR gene. In gel mobility-shift assays, nuclear extracts of FRTL-5 cells and FRT cells yielded several specific bands with a probe comprising nt -116 to -80. Supershift assays with antibodies to GABPalpha and to GABPbeta1 showed that GABP was a component of the probe complexes formed by the nuclear extracts. Immunoblot analysis confirmed the presence of both GABP subunits in the nuclear extracts. A reporter gene construct containing the TSHR gene promoter was activated, in a dose-dependent manner, in FRTL-5 cells by cotransfection with constructs encoding both GABPalpha and GABPbeta1. Both GABP binding to and activation of the TSHR gene promoter were prevented by methylation of CpG sites at nt -93 and -85. These CpG sites were highly methylated (>82%) in FRT cells and completely demethylated in FRTL-5 cells, consistent with expression of the TSHR gene in the latter, but not the former. These results suggest that GABP regulates transcription of the TSHR gene in a methylation-dependent manner and that methylation of specific CpG sites and the methylation sensitivity of GABP contribute to the failure of FRT cells to express the endogenous TSHR gene.
Collapse
Affiliation(s)
- N Yokomori
- Third Department of Internal Medicine, Yamanashi Medical University, Tamaho, Japan
| | | | | | | | | |
Collapse
|
38
|
Goto T, Monk M. Regulation of X-chromosome inactivation in development in mice and humans. Microbiol Mol Biol Rev 1998; 62:362-78. [PMID: 9618446 PMCID: PMC98919 DOI: 10.1128/mmbr.62.2.362-378.1998] [Citation(s) in RCA: 202] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Dosage compensation for X-linked genes in mammals is accomplished by inactivating one of the two X chromosomes in females. X-chromosome inactivation (XCI) occurs during development, coupled with cell differentiation. In somatic cells, XCI is random, whereas in extraembryonic tissues, XCI is imprinted in that the paternally inherited X chromosome is preferentially inactivated. Inactivation is initiated from an X-linked locus, the X-inactivation center (Xic), and inactivity spreads along the chromosome toward both ends. XCI is established by complex mechanisms, including DNA methylation, heterochromatinization, and late replication. Once established, inactivity is stably maintained in subsequent cell generations. The function of an X-linked regulatory gene, Xist, is critically involved in XCI. The Xist gene maps to the Xic, it is transcribed only from the inactive X chromosome, and the Xist RNA associates with the inactive X chromosome in the nucleus. Investigations with Xist-containing transgenes and with deletions of the Xist gene have shown that the Xist gene is required in cis for XCI. Regulation of XCI is therefore accomplished through regulation of Xist. Transcription of the Xist gene is itself regulated by DNA methylation. Hence, the differential methylation of the Xist gene observed in sperm and eggs and its recognition by protein binding constitute the most likely mechanism regulating imprinted preferential expression of the paternal allele in preimplantation embryos and imprinted paternal XCI in extraembryonic tissues. This article reviews the mechanisms underlying XCI and recent advances elucidating the functions of the Xist gene in mice and humans.
Collapse
Affiliation(s)
- T Goto
- Molecular Embryology Unit, Institute of Child Health, London WC1N 1EH, United Kingdom.
| | | |
Collapse
|
39
|
Jiang PP, Frederick K, Hansen TH, Miller RD. Localization of the mouse gene releasing sex-limited expression of Slp. Proc Natl Acad Sci U S A 1996; 93:913-7. [PMID: 8570659 PMCID: PMC40158 DOI: 10.1073/pnas.93.2.913] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
To probe genetic variation in the regulation of sexual dimorphism, we have characterized the mouse protein Slp, coded by the gene sex-limited protein (Slp). Slp expression in many strains is limited to males and is androgen-dependent. However, female expression is also observed in rare strains, due to nonlinked gene(s) termed regulator of sex-limitation (rsl). In this report we demonstrate that female expression of Slp results from homozygous recessive allele(s) at a single autosomal locus that maps to a 2.2-centimorgan interval on chromosome 13. This conclusion was supported by extensive genetic analyses including the use of polymorphic microsatellites to type numerous backcross progeny and a recombinant inbred series and to identify the congenic interval in three independently derived congenic strains. Four attractive candidate genes were identified by the localization of rsl. Interestingly, rsl was found not only to enable expression in females but to also increase expression in males. The findings suggest that the expression of Slp and perhaps other sexually dimorphic proteins is regulated by two pathways, one that is dependent upon rsl but not androgens and another that is rsl-independent but requires androgens.
Collapse
Affiliation(s)
- P P Jiang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | | | | |
Collapse
|
40
|
Yokomori N, Kobayashi R, Moore R, Sueyoshi T, Negishi M. A DNA methylation site in the male-specific P450 (Cyp 2d-9) promoter and binding of the heteromeric transcription factor GABP. Mol Cell Biol 1995; 15:5355-62. [PMID: 7565685 PMCID: PMC230784 DOI: 10.1128/mcb.15.10.5355] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Cyp 2d-9 gene encodes the male-specific steroid 16 alpha-hydroxylase in mouse liver and shares a conserved regulatory element (-100TTCCGGGC-93) with another male-specific Slp promoter. As shown with the Slp promoter (N. Yokomori, R. Moore, and M. Negishi, Proc. Natl. Acad. Sci. USA 92:1302-1306, 1995), the male-preferential demethylation also occurs at CpG/-97 in the Cyp 2d-9 promoter. The transcription factor which specifically binds to the demethylated element has been purified. The peptide sequences reveal that the factor consists of GABP alpha and GABP beta 1 with Ets and Notch motifs, respectively. Both DNase I footprinting and gel shift assays indicate that the bacterially expressed glutathione S-transferase-GABP fusion proteins bind to the regulatory element only when CpG/-97 is demethylated. Moreover, Cyp 2d-9 promoter is trans-activated by coexpression of GABP proteins in HepG2 cells. Given the additional results that CpG/-50 of the female-specific steroid 15 alpha-hydroxylase (Cyp 2a-4) promoter is preferentially demethylated in the females, the sex-specific expressions of the P450 genes correlate very well with DNA demethylation. We also conclude that GABP is a methylation-sensitive transcription factor and is a potential transcription activator of the male-specific Cyp 2d-9 promoter.
Collapse
Affiliation(s)
- N Yokomori
- Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | |
Collapse
|