DNA Methylation Loci in Placenta Associated with Birthweight And
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Tekola-Ayele et al. Clinical Epigenetics (2020) 12:78 https://doi.org/10.1186/s13148-020-00873-x RESEARCH Open Access DNA methylation loci in placenta associated with birthweight and expression of genes relevant for early development and adult diseases Fasil Tekola-Ayele1* , Xuehuo Zeng2, Marion Ouidir1, Tsegaselassie Workalemahu1, Cuilin Zhang1, Fabien Delahaye3,4 and Ronald Wapner5 Abstract Background: Birthweight marks an important milestone of health across the lifespan, including cardiometabolic disease risk in later life. The placenta, a transient organ at the maternal-fetal interface, regulates fetal growth. Identifying genetic loci where DNA methylation in placenta is associated with birthweight can unravel genomic pathways that are dysregulated in aberrant fetal growth and cardiometabolic diseases in later life. Results: We performed placental epigenome-wide association study (EWAS) of birthweight in an ethnic diverse cohort of pregnant women (n = 301). Methylation at 15 cytosine-(phosphate)-guanine sites (CpGs) was associated with birthweight (false discovery rate (FDR) < 0.05). Methylation at four (26.7%) CpG sites was associated with placental transcript levels of 15 genes (FDR < 0.05), including genes known to be associated with adult lipid traits, inflammation and oxidative stress. Increased methylation at cg06155341 was associated with higher birthweight and lower FOSL1 expression, and lower FOSL1 expression was correlated with higher birthweight. Given the role of the FOSL1 transcription factor in regulating developmental processes at the maternal-fetal interface, epigenetic mechanisms at this locus may regulate fetal development. We demonstrated trans-tissue portability of methylation at four genes (MLLT1, PDE9A, ASAP2, and SLC20A2) implicated in birthweight by a previous study in cord blood. We also found that methylation changes known to be related to maternal underweight, preeclampsia and adult type 2 diabetes were associated with lower birthweight in placenta. Conclusion: We identified novel placental DNA methylation changes associated with birthweight. Placental epigenetic mechanisms may underlie dysregulated fetal development and early origins of adult cardiometabolic diseases. Clinical trial registration: ClinicalTrials.gov, NCT00912132 Keywords: Placenta, Birthweight, Fetal growth, DNA methylation, Transcriptomics, Expression quantitative trait methylation (eQTM), Developmental origins of health and disease (DOHaD) * Correspondence: [email protected] 1Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 6710B Rockledge Dr, room 3204, Bethesda, MD 20892, USA Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Tekola-Ayele et al. Clinical Epigenetics (2020) 12:78 Page 2 of 14 Background Eunice Kennedy Shriver National Institute of Child Birthweight is a complex multifactorial trait relevant for Health and Human Development (NICHD) Fetal health and disease in childhood and adulthood. Abnor- Growth Studies–Singletons cohort [28, 29]. For CpGs mal birthweight has been consistently associated with in- found to be significantly associated with birthweight in fant mortality and morbidity, childhood obesity, and our analysis, we investigated the associations between cardiometabolic diseases in adulthood [1–3]. Complex methylation levels at the CpGs and expression of the interplays between genetic and environmental influences proximal genes in placenta. We also tested for correla- play important roles in regulating fetal growth and de- tions between placental expression of those genes and velopment [4]. Epigenetic mechanisms such as DNA birthweight. Pathway analyses, functional annotations, methylation may represent the regulatory links between and genetic variants associated with DNA methylation genetic and environmental influences on birthweight [5]. were explored to understand the biological context that Identifying DNA methylation loci that are associated may explain the relationship between the differentially with birthweight can give clues to detect molecular bio- methylated CpGs and birthweight. The placenta may markers of aberrant fetal growth and cardiometabolic harbor the epigenetic links between maternal cardiomet- diseases in later life. The placenta is known for its prom- abolic status, fetal growth and risk of cardiometabolic inent relevance in fetal growth and development due to diseases in later life. Therefore, for CpGs in offspring tis- its roles in nutrient transport, immune regulation, and sues known to be related to maternal perinatal cardio- hormonal functions [6]. Compromised placental func- metabolic traits and CpGs in adult tissues known to be tion has often been associated with aberrant fetal growth related to cardiometabolic diseases, we tested whether [7] and risk of cardiometabolic diseases in later life [8]. methylation in placenta was associated with birthweight. DNA methylation in placenta is critical for placental Our findings of novel genomic loci associated with birth- development and regulation of trophoblast invasion, fac- weight and overlaps with adult cardiometabolic diseases tors important for fetal growth outcomes [9, 10]. The lend insights into the pathophysiology of fetal growth DNA methylation profile of the placenta undergoes dy- and potential molecular targets to prevent cardiometa- namic changes [11–13], potentially due to cumulative bolic diseases in later life. environmental exposures, adaptive changes in placental cell composition, and genetic regulation [13]. DNA methylation in placenta regulates gene expression and Results cellular function and may be one mechanism by which Data set environmental exposures and genetic variation influence We used DNA methylation data measured using Illumi- fetal growth. Therefore, DNA methylation loci associ- na’s Infinium Human Methylation450 Beadchip (Illu- ated with birthweight can point to molecular signatures mina Inc., San Diego, CA) on placentas obtained at of the intrauterine environment and may lend insights delivery from 301 pregnant women who participated in to understand the links between fetal growth and cardio- the NICHD Fetal Growth Studies–Singletons [28, 29]. metabolic diseases in later life. Epigenome-wide associ- The self-reported race/ethnic profiles of the 301 women ation studies (EWASs) have identified several cord blood were 102 Hispanics, 77 Whites, 72 Blacks, and 50 DNA methylation cytosine-phosphate-guanine sites Asians. None of the pregnant women smoked cigarettes (CpGs) associated with birthweight [14–18]. Although in the past 6 months prior to conception. The mean (± cord blood is a more accessible tissue for genomic stud- standard deviation (SD)) birthweight and gestational age ies, the placenta may be a more biologically relevant tis- at delivery were 3165 (± 451) g and 39.5 (± 1.1) weeks, sue for studying the epigenetic regulation of fetal growth respectively. Detailed characteristics of participants of and development. Previous studies in placenta reported the NICHD Fetal Growth Studies and the 301 women that birthweight status is significantly associated with and neonates included in the present study have been long interspersed nuclear elements (LINE)-1 methylation described previously [28, 29]. The major characteristics in placenta [19, 20], global placental DNA methylation of the 301 women were similar to those in the overall [21], and methylation levels at selected candidate gene NICHD Fetal Growth Studies cohort, except pre- regions [22–25] and at CpGs assayed using the Human- pregnancy body mass index (Additional Table 1). Gene Methylation27 BeadChip array [26, 27]. An EWAS of expression profile of a subset of the placental samples (n birthweight using placental samples profiled using more = 80) was obtained from RNA sequencing performed on recently developed dense DNA methylation arrays is the Illumina HiSeq2000 system. The self-reported race/ warranted to unravel novel genetic loci. ethnic profiles of the 80 women were 28 Hispanics, 24 In this study, we examined the association between Whites, 20 Blacks, and 8 Asians. Both DNA methylation birthweight and epigenome-wide DNA methylation in and gene expression profiles were available in a total of placental samples obtained from participants of the 75 placental samples [29]. Tekola-Ayele et al. Clinical Epigenetics (2020)