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Hart DA. The Heterogeneity of Post-Menopausal Disease Risk: Could the Basis for Why Only Subsets of Females Are Affected Be Due to a Reversible Epigenetic Modification System Associated with Puberty, Menstrual Cycles, Pregnancy and Lactation, and, Ultimately, Menopause? Int J Mol Sci 2024; 25:3866. [PMID: 38612676 PMCID: PMC11011715 DOI: 10.3390/ijms25073866] [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: 02/24/2024] [Revised: 03/19/2024] [Accepted: 03/28/2024] [Indexed: 04/14/2024] Open
Abstract
For much of human evolution, the average lifespan was <40 years, due in part to disease, infant mortality, predators, food insecurity, and, for females, complications of childbirth. Thus, for much of evolution, many females did not reach the age of menopause (45-50 years of age) and it is mainly in the past several hundred years that the lifespan has been extended to >75 years, primarily due to public health advances, medical interventions, antibiotics, and nutrition. Therefore, the underlying biological mechanisms responsible for disease risk following menopause must have evolved during the complex processes leading to Homo sapiens to serve functions in the pre-menopausal state. Furthermore, as a primary function for the survival of the species is effective reproduction, it is likely that most of the advantages of having such post-menopausal risks relate to reproduction and the ability to address environmental stresses. This opinion/perspective will be discussed in the context of how such post-menopausal risks could enhance reproduction, with improved survival of offspring, and perhaps why such risks are preserved. Not all post-menopausal females exhibit risk for this set of diseases, and those who do develop such diseases do not have all of the conditions. The diseases of the post-menopausal state do not operate as a unified complex, but as independent variables, with the potential for some overlap. The how and why there would be such heterogeneity if the risk factors serve essential functions during the reproductive years is also discussed and the concept of sets of reversible epigenetic changes associated with puberty, pregnancy, and lactation is offered to explain the observations regarding the distribution of post-menopausal conditions and their potential roles in reproduction. While the involvement of an epigenetic system with a dynamic "modification-demodification-remodification" paradigm contributing to disease risk is a hypothesis at this point, validation of it could lead to a better understanding of post-menopausal disease risk in the context of reproduction with commonalities may also lead to future improved interventions to control such risk after menopause.
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Affiliation(s)
- David A Hart
- Department of Surgery, Faculty of Kinesiology, and McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB T2N 4N1, Canada
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2
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Krasic J, Fucic A, Sincic N, Sindicic Dessardo N, Starcevic M, Guszak V, Ceppi M, Bruzzone M, Kralik S. Comparison of Estradiol, Testostosterone, and CYP19 Methylation Levels between Full-Term and Preterm Newborns. Horm Res Paediatr 2022; 94:168-175. [PMID: 34348285 DOI: 10.1159/000518112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/24/2021] [Indexed: 11/19/2022] Open
Abstract
Estradiol (E), testosterone (T), and their ratio are crucial axis in life. Especially during intrauterine growth, they orchestrate the complex development of organs and their interaction, which have lifelong impact on health and an organism's capacity to respond to environmental stressors. The aim of this study was to compare for the first time E, T, and their ratio levels with aromatase (CYP19) gene methylation levels between preterm newborns (PN) and full-term newborns (FN) with respect to their mother's environmental exposure and diet. In this study, 56 FN of 37-42 weeks of gestation age (GA) and 46 PN at GA 27-36 weeks were analysed for E and T levels and CYP19A1 gene pI.3/II promoter region methylation. Results showed there was no difference in E levels between PN and FN, but there were significantly lower levels of T in PN than in FN (2.81 nmol vs. 3.76 nmol, respectively) and consequently a significantly higher E/T ratio in PN than in FN (5278.04 vs. 2891.23, respectively). CYP19A1 methylation was significantly lower in PN than in FN (86.04% vs. 90.04%, respectively). CYP19A1 methylation was significantly reduced in newborns whose mothers reported daily milk consumption. Our study is the first to provide referent values for CYP19A1 methylation levels in FN and PN and shows that PN and FN significantly differ in CYP19A1 methylation levels, T levels, and E/T ratio. Future research should further investigate the mechanisms involved in GA-dependent CYP19A1 methylation levels and mechanisms of sex hormone disturbances which may contribute to preterm birth.
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Affiliation(s)
- Jure Krasic
- Medical School, University of Zagreb, Zagreb, Croatia.,Scientific Center of Excellence for Reproductive and Regenerative Medicine (CERRM), Zagreb, Croatia
| | - Aleksandra Fucic
- Scientific Center of Excellence for Reproductive and Regenerative Medicine (CERRM), Zagreb, Croatia.,Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Nino Sincic
- Medical School, University of Zagreb, Zagreb, Croatia.,Scientific Center of Excellence for Reproductive and Regenerative Medicine (CERRM), Zagreb, Croatia
| | - Nada Sindicic Dessardo
- Scientific Center of Excellence for Reproductive and Regenerative Medicine (CERRM), Zagreb, Croatia.,University Hospital Center Zagreb, Zagreb, Croatia
| | - Mirta Starcevic
- Scientific Center of Excellence for Reproductive and Regenerative Medicine (CERRM), Zagreb, Croatia.,University Hospital Center Zagreb, Zagreb, Croatia
| | - Vedrana Guszak
- Scientific Center of Excellence for Reproductive and Regenerative Medicine (CERRM), Zagreb, Croatia.,University Hospital Center Zagreb, Zagreb, Croatia
| | - Marcello Ceppi
- Clinical Epidemiology Unit, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Marco Bruzzone
- Clinical Epidemiology Unit, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Sasa Kralik
- University Hospital Center Zagreb, Zagreb, Croatia
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Budd AM, Robins JB, Whybird O, Jerry DR. Epigenetics underpins phenotypic plasticity of protandrous sex change in fish. Ecol Evol 2022; 12:e8730. [PMID: 35342607 PMCID: PMC8931711 DOI: 10.1002/ece3.8730] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 02/22/2022] [Indexed: 11/06/2022] Open
Abstract
Phenotypic plasticity is an important driver of species resilience. Often mediated by epigenetic changes, phenotypic plasticity enables individual genotypes to express variable phenotypes in response to environmental change. Barramundi (Lates calcarifer) are a protandrous (male‐first) sequential hermaphrodite that exhibits plasticity in length‐at‐sex change between geographic regions. This plasticity is likely to be mediated by changes in DNA methylation (DNAm), a well‐studied epigenetic modification. To investigate the relationships between length, sex, and DNAm in a sequential hermaphrodite, here, we compare DNAm in four conserved vertebrate sex‐determining genes in male and female barramundi of differing lengths from three geographic regions of northern Australia. Barramundi first mature as male and later sex change to female upon the attainment of a larger body size; however, a general pattern of increasing female‐specific DNAm markers with increasing length was not observed. Significant differences in DNAm between males and females of similar lengths suggest that female‐specific DNAm arises rapidly during sex change, rather than gradually with fish growth. The findings also reveal that region‐specific differences in length‐at‐sex change are accompanied by differences in DNAm and are consistent with variability in remotely sensed sea temperature and salinity. Together, these findings provide the first in situ evidence for epigenetically and environmentally mediated sex change in a protandrous hermaphrodite and offer significant insight into the molecular and ecological processes governing the marked and unique plasticity of sex in fish.
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Affiliation(s)
- Alyssa M. Budd
- Centre for Sustainable Tropical Fisheries and Aquaculture James Cook University Townsville Qld Australia
- Centre for Tropical Bioinformatics and Molecular Biology James Cook University Townsville Qld Australia
| | - Julie B. Robins
- Ecosciences Precinct Department of Agriculture and Fisheries Brisbane Qld Australia
| | - Olivia Whybird
- Northern Fisheries Centre Department of Agriculture and Fisheries Cairns Qld Australia
| | - Dean R. Jerry
- Centre for Sustainable Tropical Fisheries and Aquaculture James Cook University Townsville Qld Australia
- Tropical Futures Institute James Cook University Singapore City Singapore
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4
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Nautiyal H, Imam SS, Alshehri S, Ghoneim MM, Afzal M, Alzarea SI, Güven E, Al-Abbasi FA, Kazmi I. Polycystic Ovarian Syndrome: A Complex Disease with a Genetics Approach. Biomedicines 2022; 10:biomedicines10030540. [PMID: 35327342 PMCID: PMC8945152 DOI: 10.3390/biomedicines10030540] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/13/2022] [Accepted: 02/16/2022] [Indexed: 01/27/2023] Open
Abstract
Polycystic ovarian syndrome (PCOS) is a complex endocrine disorder affecting females in their reproductive age. The early diagnosis of PCOS is complicated and complex due to overlapping symptoms of this disease. The most accepted diagnostic approach today is the Rotterdam Consensus (2003), which supports the positive diagnosis of PCOS when patients present two out of the following three symptoms: biochemical and clinical signs of hyperandrogenism, oligo, and anovulation, also polycystic ovarian morphology on sonography. Genetic variance, epigenetic changes, and disturbed lifestyle lead to the development of pathophysiological disturbances, which include hyperandrogenism, insulin resistance, and chronic inflammation in PCOS females. At the molecular level, different proteins and molecular and signaling pathways are involved in disease progression, which leads to the failure of a single genetic diagnostic approach. The genetic approach to elucidate the mechanism of pathogenesis of PCOS was recently developed, whereby four phenotypic variances of PCOS categorize PCOS patients into classic, ovulatory, and non-hyperandrogenic types. Genetic studies help to identify the root cause for the development of this PCOS. PCOS genetic inheritance is autosomal dominant but the latest investigations revealed it as a multigene origin disease. Different genetic loci and specific genes have been identified so far as being associated with this disease. Genome-wide association studies (GWAS) and related genetic studies have changed the scenario for the diagnosis and treatment of this reproductive and metabolic condition known as PCOS. This review article briefly discusses different genes associated directly or indirectly with disease development and progression.
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Affiliation(s)
- Himani Nautiyal
- Siddhartha Institute of Pharmacy, Near IT-Park, Sahastradhara Road, Dehradun 248001, India;
| | - Syed Sarim Imam
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia; (S.S.I.); (S.A.)
| | - Sultan Alshehri
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia; (S.S.I.); (S.A.)
| | - Mohammed M. Ghoneim
- Department of Pharmacy Practice, College of Pharmacy, AlMaarefa University, Ad Diriyah 13713, Saudi Arabia;
| | - Muhammad Afzal
- Department of Pharmacology, College of Pharmacy, Jouf University, Sakaka 72341, Saudi Arabia;
- Correspondence: (M.A.); (I.K.)
| | - Sami I. Alzarea
- Department of Pharmacology, College of Pharmacy, Jouf University, Sakaka 72341, Saudi Arabia;
| | - Emine Güven
- Biomedical Engineering Department, Faculty of Engineering, Düzce University, Düzce 81620, Turkey;
| | - Fahad A. Al-Abbasi
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Imran Kazmi
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
- Correspondence: (M.A.); (I.K.)
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5
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Polycystic Ovary Syndrome: A Brain Disorder Characterized by Eating Problems Originating during Puberty and Adolescence. Int J Mol Sci 2020; 21:ijms21218211. [PMID: 33153014 PMCID: PMC7663730 DOI: 10.3390/ijms21218211] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 02/07/2023] Open
Abstract
Polycystic ovary syndrome (PCOS) is an endocrine condition associated with reproductive and psychiatric disorders, and with obesity. Eating disorders, such as bulimia and recurrent dieting, are also linked to PCOS. They can lead to the epigenetic dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis, thereby impacting on ovarian folliculogenesis. We postulate that PCOS is induced by psychological distress and episodes of overeating and/or dieting during puberty and adolescence, when body dissatisfaction and emotional distress are often present. We propose that upregulated activation of the central HPG axis during this period can be epigenetically altered by psychological stressors and by bulimia/recurrent dieting, which are common during adolescence and which can lead to PCOS. This hypothesis is based on events that occur during a largely neglected stage of female reproductive development. To date, most research into the origins of PCOS has focused on the prenatal induction of this disorder, particularly in utero androgenization and the role of anti-Müllerian hormone. Establishing causality in our peripubertal model requires prospective cohort studies from infancy. Mechanistic studies should consider the role of the gut microbiota in addition to the epigenetic regulation of (neuro) hormones. Finally, clinicians should consider the importance of underlying chronic psychological distress and eating disorders in PCOS.
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6
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Fonseca PADS, Id-Lahoucine S, Reverter A, Medrano JF, Fortes MS, Casellas J, Miglior F, Brito L, Carvalho MRS, Schenkel FS, Nguyen LT, Porto-Neto LR, Thomas MG, Cánovas A. Combining multi-OMICs information to identify key-regulator genes for pleiotropic effect on fertility and production traits in beef cattle. PLoS One 2018; 13:e0205295. [PMID: 30335783 PMCID: PMC6193631 DOI: 10.1371/journal.pone.0205295] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/21/2018] [Indexed: 12/21/2022] Open
Abstract
The identification of biological processes related to the regulation of complex traits is a difficult task. Commonly, complex traits are regulated through a multitude of genes contributing each to a small part of the total genetic variance. Additionally, some loci can simultaneously regulate several complex traits, a phenomenon defined as pleiotropy. The lack of understanding on the biological processes responsible for the regulation of these traits results in the decrease of selection efficiency and the selection of undesirable hitchhiking effects. The identification of pleiotropic key-regulator genes can assist in developing important tools for investigating biological processes underlying complex traits. A multi-breed and multi-OMICs approach was applied to study the pleiotropic effects of key-regulator genes using three independent beef cattle populations evaluated for fertility traits. A pleiotropic map for 32 traits related to growth, feed efficiency, carcass and meat quality, and reproduction was used to identify genes shared among the different populations and breeds in pleiotropic regions. Furthermore, data-mining analyses were performed using the Cattle QTL database (CattleQTLdb) to identify the QTL category annotated in the regions around the genes shared among breeds. This approach allowed the identification of a main gene network (composed of 38 genes) shared among breeds. This gene network was significantly associated with thyroid activity, among other biological processes, and displayed a high regulatory potential. In addition, it was possible to identify genes with pleiotropic effects related to crucial biological processes that regulate economically relevant traits associated with fertility, production and health, such as MYC, PPARG, GSK3B, TG and IYD genes. These genes will be further investigated to better understand the biological processes involved in the expression of complex traits and assist in the identification of functional variants associated with undesirable phenotypes, such as decreased fertility, poor feed efficiency and negative energetic balance.
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Affiliation(s)
- Pablo Augusto de Souza Fonseca
- University of Guelph, Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, Guelph, Ontario, Canada
- Universidade Federal de Minas Gerais, Departamento de Biologia Geral, Belo Horizonte, Minas Gerais, Brazil
| | - Samir Id-Lahoucine
- University of Guelph, Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, Guelph, Ontario, Canada
| | - Antonio Reverter
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, Brisbane, Queensland, Australia
| | - Juan F. Medrano
- University of California-Davis, Department of Animal Science, Davis, California, United States of America
| | - Marina S. Fortes
- The University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, Queensland, Australia
| | - Joaquim Casellas
- Universitat Autònoma de Barcelona, Departament de Ciència Animal i dels Aliments, Barcelona, Bellaterra, Barcelona, Spain
| | - Filippo Miglior
- University of Guelph, Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, Guelph, Ontario, Canada
- Canadian Dairy Network, Guelph, Ontario, Canada
| | - Luiz Brito
- University of Guelph, Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, Guelph, Ontario, Canada
| | - Maria Raquel S. Carvalho
- Universidade Federal de Minas Gerais, Departamento de Biologia Geral, Belo Horizonte, Minas Gerais, Brazil
| | - Flávio S. Schenkel
- University of Guelph, Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, Guelph, Ontario, Canada
| | - Loan T. Nguyen
- The University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, Queensland, Australia
| | - Laercio R. Porto-Neto
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, Brisbane, Queensland, Australia
| | - Milton G. Thomas
- Colorado State University, Department of Animal Science, Fort-Colins, Colorado, United States of America
| | - Angela Cánovas
- University of Guelph, Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, Guelph, Ontario, Canada
- * E-mail:
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7
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Nishitani S, Parets SE, Haas BW, Smith AK. DNA methylation analysis from saliva samples for epidemiological studies. Epigenetics 2018; 13:352-362. [PMID: 29912612 DOI: 10.1080/15592294.2018.1461295] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
Abstract
Saliva is a non-invasive, easily accessible tissue, which is regularly collected in large epidemiological studies to examine genetic questions. Recently, it is becoming more common to use saliva to assess DNA methylation. However, DNA extracted from saliva is a mixture of both bacterial and human DNA derived from epithelial and immune cells in the mouth. Thus, there are unique challenges to using salivary DNA in methylation studies that can influence data quality. This study assesses: (1) quantification of human DNA after extraction; (2) delineation of human and bacterial DNA; (3) bisulfite conversion (BSC); (4) quantification of BSC DNA; (5) PCR amplification of BSC DNA from saliva and; (6) quantitation of DNA methylation with a targeted assay. The framework proposed will allow saliva samples to be more widely used in targeted epigenetic studies.
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Affiliation(s)
- Shota Nishitani
- a Department of Gynecology and Obstetrics , Emory University School of Medicine , Atlanta , GA , USA.,b Department of Psychiatry and Behavioral Sciences , Emory University School of Medicine , Atlanta , GA , USA
| | - Sasha E Parets
- b Department of Psychiatry and Behavioral Sciences , Emory University School of Medicine , Atlanta , GA , USA
| | - Brian W Haas
- c Department of Psychology , University of Georgia , Athens , GA , USA
| | - Alicia K Smith
- a Department of Gynecology and Obstetrics , Emory University School of Medicine , Atlanta , GA , USA.,b Department of Psychiatry and Behavioral Sciences , Emory University School of Medicine , Atlanta , GA , USA
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8
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Yang C, Gao X, Ye J, Ding J, Liu Y, Liu H, Li X, Zhang Y, Zhou J, Huang W, Fang F, Ling Y. The interaction between DNA methylation and long non-coding RNA during the onset of puberty in goats. Reprod Domest Anim 2018; 53:1287-1297. [PMID: 29981216 DOI: 10.1111/rda.13246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 05/29/2018] [Indexed: 01/17/2023]
Abstract
Epigenetics plays an important role in controlling female puberty. Both DNA methylation and long non-coding RNAs (lncRNA) regulate the initiation of puberty by affecting the expression of genes related to puberty. While recent studies have indicated that DNA methylation of lncRNA represses the expression of lncRNA, its role in regulating puberty remains unclear. To explore the mechanism between DNA methylation and lncRNAs during puberty onset, we performed whole-genome bisulphite sequencing (WGBS) and RNA-sequencing (RNA-seq). We found that DNA methylation was inversely correlated to gene expression levels during puberty. Methylation levels gradually decreased near the transcription initiation site and were present at high levels in the exon, intron and 3' untranslated regions. In the promoter, lncRNA expression was negatively related to DNA methylation. We reported hypermethylation in the gene body and downstream of the lncRNA compared with upstream regions. In GO and KEGG analyses, we found enriched target genes of lncRNA, XLOC_960044 and XLOC_767346. During puberty, methylation of these genes increased while expression decreased. Our study indicates that DNA methylation of the promoter is negatively correlated with lncRNA during puberty onset, and methylation regulates the initiation of puberty via lncRNA, which provides new insight into the epigenetic mechanism of puberty onset.
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Affiliation(s)
- Chen Yang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Xiaoxiao Gao
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Jing Ye
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Jianping Ding
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Ya Liu
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Hongyu Liu
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Xiumei Li
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Yunhai Zhang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Jie Zhou
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Weiping Huang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Fugui Fang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Yinghui Ling
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, Hefei, China.,Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
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9
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Avendaño MS, Vazquez MJ, Tena-Sempere M. Disentangling puberty: novel neuroendocrine pathways and mechanisms for the control of mammalian puberty. Hum Reprod Update 2018; 23:737-763. [PMID: 28961976 DOI: 10.1093/humupd/dmx025] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 08/01/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Puberty is a complex developmental event, controlled by sophisticated regulatory networks that integrate peripheral and internal cues and impinge at the brain centers driving the reproductive axis. The tempo of puberty is genetically determined but is also sensitive to numerous modifiers, from metabolic and sex steroid signals to environmental factors. Recent epidemiological evidence suggests that the onset of puberty is advancing in humans, through as yet unknown mechanisms. In fact, while much knowledge has been gleaned recently on the mechanisms responsible for the control of mammalian puberty, fundamental questions regarding the intimate molecular and neuroendocrine pathways responsible for the precise timing of puberty and its deviations remain unsolved. OBJECTIVE AND RATIONALE By combining data from suitable model species and humans, we aim to provide a comprehensive summary of our current understanding of the neuroendocrine mechanisms governing puberty, with particular focus on its central regulatory pathways, underlying molecular basis and mechanisms for metabolic control. SEARCH METHODS A comprehensive MEDLINE search of articles published mostly from 2003 to 2017 has been carried out. Data from cellular and animal models (including our own results) as well as clinical studies focusing on the pathophysiology of puberty in mammals were considered and cross-referenced with terms related with central neuroendocrine mechanisms, metabolic control and epigenetic/miRNA regulation. OUTCOMES Studies conducted during the last decade have revealed the essential role of novel central neuroendocrine pathways in the control of puberty, with a prominent role of kisspeptins in the precise regulation of the pubertal activation of GnRH neurosecretory activity. In addition, different transmitters, including neurokinin-B (NKB) and, possibly, melanocortins, have been shown to interplay with kisspeptins in tuning puberty onset. Alike, recent studies have documented the role of epigenetic mechanisms, involving mainly modulation of repressors that target kisspeptins and NKB pathways, as well as microRNAs and the related binding protein, Lin28B, in the central control of puberty. These novel pathways provide the molecular and neuroendocrine basis for the modulation of puberty by different endogenous and environmental cues, including nutritional and metabolic factors, such as leptin, ghrelin and insulin, which are known to play an important role in pubertal timing. WIDER IMPLICATIONS Despite recent advancements, our understanding of the basis of mammalian puberty remains incomplete. Complete elucidation of the novel neuropeptidergic and molecular mechanisms summarized in this review will not only expand our knowledge of the intimate mechanisms responsible for puberty onset in humans, but might also provide new tools and targets for better prevention and management of pubertal deviations in the clinical setting.
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Affiliation(s)
- M S Avendaño
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,Department of Cell Biology, Physiology and Immunology, Faculty of Medicine, University of Córdoba, Avda. Menéndez Pidal s/n. 14004 Córdoba, Spain.,Hospital Universitario Reina Sofia, Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain
| | - M J Vazquez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,Department of Cell Biology, Physiology and Immunology, Faculty of Medicine, University of Córdoba, Avda. Menéndez Pidal s/n. 14004 Córdoba, Spain.,Hospital Universitario Reina Sofia, Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain
| | - M Tena-Sempere
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,Department of Cell Biology, Physiology and Immunology, Faculty of Medicine, University of Córdoba, Avda. Menéndez Pidal s/n. 14004 Córdoba, Spain.,Hospital Universitario Reina Sofia, Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Avda. Menéndez Pidal, s/n, 14004 Córdoba, Spain.,FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland
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10
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Langie SAS, Moisse M, Declerck K, Koppen G, Godderis L, Vanden Berghe W, Drury S, De Boever P. Salivary DNA Methylation Profiling: Aspects to Consider for Biomarker Identification. Basic Clin Pharmacol Toxicol 2017; 121 Suppl 3:93-101. [PMID: 27901320 PMCID: PMC5644718 DOI: 10.1111/bcpt.12721] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/22/2016] [Indexed: 12/13/2022]
Abstract
Is it not more comfortable to spit saliva in a tube than to be pricked with a needle to draw blood to analyse your health and disease risk? Many patients, study participants and (parents of) young children undoubtedly prefer non-invasive and convenient procedures. Such procedures increase compliance rates especially for longitudinal prospective studies. Saliva is an attractive biofluid providing good quality DNA to study epigenetic mechanisms underlying disease across development. In this MiniReview, we will describe the different applications of saliva in the field of epigenetics, focusing on genomewide methylation analysis. Advantages of the use of saliva and its comparability with blood will be discussed, as will the challenges in data processing and interpretation. Knowledge gaps will be identified and suggestions given on how to improve the analysis, making saliva 'the' biofluid of choice for future biomarker initiatives in many different epidemiological and public health studies.
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Affiliation(s)
- Sabine A. S. Langie
- Environmental Risk and Health UnitFlemish Institute for Technological Research (VITO)MolBelgium
- Faculty of SciencesHasselt UniversityDiepenbeekBelgium
| | | | - Ken Declerck
- Laboratory of Protein Chemistry, Proteomics and Epigenetic SignalingDepartment of Biomedical SciencesUniversity of AntwerpWilrijkBelgium
| | - Gudrun Koppen
- Environmental Risk and Health UnitFlemish Institute for Technological Research (VITO)MolBelgium
| | - Lode Godderis
- Centre Environment & HealthDepartment of Public Health and Primary CareKU LeuvenLeuvenBelgium
- IDEWEExternal Service for Prevention and Protection at WorkHeverleeBelgium
| | - Wim Vanden Berghe
- Laboratory of Protein Chemistry, Proteomics and Epigenetic SignalingDepartment of Biomedical SciencesUniversity of AntwerpWilrijkBelgium
| | - Stacy Drury
- The Brain InstituteTulane UniversityNew OrleansLAUSA
- Department of Psychiatry and Behavioral ScienceTulane University School of MedicineNew OrleansLAUSA
| | - Patrick De Boever
- Environmental Risk and Health UnitFlemish Institute for Technological Research (VITO)MolBelgium
- Faculty of SciencesHasselt UniversityDiepenbeekBelgium
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11
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Rounge TB, Page CM, Lepistö M, Ellonen P, Andreassen BK, Weiderpass E. Genome-wide DNA methylation in saliva and body size of adolescent girls. Epigenomics 2016; 8:1495-1505. [DOI: 10.2217/epi-2016-0045] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Aim: We performed an epigenome-wide association study within the Finnish Health in Teens cohort to identify differential DNA methylation and its association with BMI in adolescents. Materials & methods: Differential DNA methylation analyses of 3.1 million CpG sites were performed in saliva samples from 50 lean and 50 heavy adolescent girls by genome-wide targeted bisulfite-sequencing. Results: We identified 100 CpG sites with p-values < 0.000524, seven regions by ‘bumphunting’ and five CpG islands that differed significantly between the two groups. The ten CpG sites and regions most strongly associated with BMI substantially overlapped with obesity- and insulin-related genes, including MC2R, IGFBPL1, IP6K1 and IGF2BP1. Conclusion: Our findings suggest an association between the saliva methylome and BMI in adolescence.
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Affiliation(s)
- Trine B Rounge
- Genetic Epidemiology Group, Folkhälsan Research Center, Helsinki, Finland
- Department of Research, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway
| | - Christian M Page
- Department of Neurology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Noncommunicable Diseases, Norwegian Institute of Public Health, Oslo, Norway
| | - Maija Lepistö
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Pekka Ellonen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Bettina K Andreassen
- Department of Research, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway
| | - Elisabete Weiderpass
- Genetic Epidemiology Group, Folkhälsan Research Center, Helsinki, Finland
- Department of Research, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway
- Department of Medical Epidemiology & Biostatistics, Karolinska Institutet, Stockholm, Sweden
- Department of Community Medicine, Faculty of Health Sciences, University of Tromsø, The Arctic University of Norway, Tromsø, Norway
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12
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Yang C, Ye J, Li X, Gao X, Zhang K, Luo L, Ding J, Zhang Y, Li Y, Cao H, Ling Y, Zhang X, Liu Y, Fang F. DNA Methylation Patterns in the Hypothalamus of Female Pubertal Goats. PLoS One 2016; 11:e0165327. [PMID: 27788248 PMCID: PMC5082945 DOI: 10.1371/journal.pone.0165327] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/10/2016] [Indexed: 11/19/2022] Open
Abstract
Female pubertal development is tightly controlled by complex mechanisms, including neuroendocrine and epigenetic regulatory pathways. Specific gene expression patterns can be influenced by DNA methylation changes in the hypothalamus, which can in turn regulate timing of puberty onset. In order to understand the relationship between DNA methylation changes and gene expression patterns in the hypothalamus of pubertal goats, whole-genome bisulfite sequencing and RNA-sequencing analyses were carried out. There was a decline in DNA methylation levels in the hypothalamus during puberty and 268 differentially methylated regions (DMR) in the genome, with differential patterns in different gene regions. There were 1049 genes identified with distinct expression patterns. High levels of DNA methylation were detected in promoters, introns and 3′-untranslated regions (UTRs). Levels of methylation decreased gradually from promoters to 5′-UTRs and increased from 5′-UTRs to introns. Methylation density analysis demonstrated that methylation level variation was consistent with the density in the promoter, exon, intron, 5′-UTRs and 3′-UTRs. Analyses of CpG island (CGI) sites showed that the enriched gene contents were gene bodies, intergenic regions and introns, and these CGI sites were hypermethylated. Our study demonstrated that DNA methylation changes may influence gene expression profiles in the hypothalamus of goats during the onset of puberty, which may provide new insights into the mechanisms involved in pubertal onset.
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Affiliation(s)
- Chen Yang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Jing Ye
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Xiumei Li
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Xiaoxiao Gao
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Kaifa Zhang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Lei Luo
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Jianping Ding
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Yunhai Zhang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Yunsheng Li
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Hongguo Cao
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Yinghui Ling
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Xiaorong Zhang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Ya Liu
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Fugui Fang
- Anhui Provincial Laboratory of Animal Genetic Resources Protection and Breeding, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Anhui Provincial Laboratory for Local Livestock and Poultry Genetic Resource Conservation and Bio-Breeding, 130 Changjiang West Road, Hefei, Anhui 230036, China
- Department of Animal Veterinary Science, College of Animal Science and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
- * E-mail:
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13
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DNA methylation of LINE-1 and Alu repetitive elements in relation to sex hormones and pubertal timing in Mexican-American children. Pediatr Res 2016; 79:855-62. [PMID: 26882368 PMCID: PMC4899098 DOI: 10.1038/pr.2016.31] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/09/2015] [Indexed: 12/21/2022]
Abstract
BACKGROUND The molecular mechanisms linking environmental exposures to earlier pubertal development are not well characterized. Epigenetics may play an important role, but data on the relationship between epigenetic marks and puberty, particularly in humans, is limited. METHODS We used pyrosequencing to measure Alu and long interspersed nucleotide elements (LINE-1) methylation in DNA isolated from whole blood samples collected from newborns and 9-y-old children (n = 266). Tanner staging was completed six times between ages 9 and 12 y to determine pubertal status, and hormone levels were measured in 12-y-old boys. RESULTS Among girls, we observed a suggestive trend of increased odds of breast and pubic hair development with higher Alu and LINE-1 methylation in 9-y-old blood, respectively. The strongest association identified was an inverse association of LINE-1 methylation in 9-y-old girls with odds of experiencing menarche by age 12 (OR (95% CI): 0.63 (0.46, 0.87); P = 0.005). We observed a consistent inverse relationship for Alu and LINE-1 methylation at 9 y with luteinizing hormone (LH), testosterone and follicle-stimulating hormone levels in boys but it was only significant between LINE-1 and LH. CONCLUSION DNA methylation of Alu and LINE-1 may be involved in puberty initiation and development. This relationship should be confirmed in future studies.
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