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Prenatal Pesticide Exposure Interacts with a Common Polymorphism in the PON1 Gene Leading to DNA Methylation Changes

ABSTRACT: Prenatal environmental conditions may influence disease risk in later life. We previously found a gene-environment interaction between the paraoxonase 1 (PON1) Q192R genotype and prenatal pesticide exposure leading to a cardio-metabolic risk profile at school age. However, the molecular mechanisms involved have not yet been resolved. It has been hypothesized that epigenetics might be involved. The aim of the present study was to investigate whether DNA methylation patterns in blood cells were related to prenatal pesticide exposure level, PON1 Q192R genotype, and associated metabolic effects observed in the children. Whole blood DNA methylation patterns in 48 children (6-11 years of age), whose mothers were occupationally unexposed or exposed to pesticides early in pregnancy, were determined by Illumina 450K methylation arrays. A specific methylation profile was observed in prenatally pesticide exposed children carrying the PON1 192R allele. Differentially methylated genes were enriched in several neuroendocrine signaling pathways including dopamine-DARPP32 feedback (appetite, reward pathways), corticotrophin releasing hormone signalling, nNOS, neuregulin signalling, mTOR signalling and type II diabetes mellitus signalling suggesting a possible link with the metabolic effects observed in these children. Furthermore, we were able to identify possible candidate genes which mediate the effect between pesticide exposure, leptin levels, delta BMI Z-score, and body fat percentage. In conclusion, DNA methylation may be an underlying mechanism explaining cardio-metabolic health outcomes in children that are prenatally exposed to pesticides and carrier of the PON1 192R allele.

ORGANISM(S): Homo sapiens

PROVIDER: GSE90117 | GEO | 2017/05/01

SECONDARY ACCESSION(S): PRJNA354431

REPOSITORIES: GEO

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Project description:Prenatal exposure to synthetic corticosteroids can significantly alter postnatal development through changes in neurotransmitters, peptides and their receptors, and thus having long-lasting behavioral effects. Some of these changes have been observed in animal experiments, others also in humans prenatally exposed to synthetic corticosteroids. Here, we focused on transcriptomic changes within the ARC of rats prenatally exposed to either betamethasone or saline. The expression of transcriptome has been assessed by novel computational tools to determine complex changes that may have life-long effects on phenotype, i.e., behavior. Total of 18,094 unigenes were quantified in the hypothalamic ARC of P14 male and female rats prenatally exposed to betametasone used in this experiment. Out of these genes, Kyoto Encyclopedia for Genes and Genomes (http://www.genome.jp) selected 112 for the dopaminergic synapse, 75 for the GABAergic and 97 for the glutamatergic synapse. We further analyzed composition, topology and modulatory networks of the genomic fabric of the dopaminergic, GABAergic, and glutamatergic synapse (the transcriptome of the most interconnected and stably expressed gene network responsible for specific transmission). Finally we investigated the M-bM-^@M-^\transcriptomic landscapeM-bM-^@M-^] of the GSF in the ARC of P14 males (M) and females (F) prenatally (G15) exposed to betamethasone (B) or saline (S). We combined in one measure (PWR = Pair-Wise Relevance) expression levels, controls and coordination of all pairs that can be formed by synapse genes with the other synapse genes, higher PWRs indicating larger influence of that gene pair to the fabric modulation. We found that prenatal exposure to betamethasone caused sex-dependent changes in the dopaminergic/GABA/glutamatergic synapse genes:. In males, 10 dopaminergic (9%), 4 GABAergic (5%) and 5 glutamatergic synapse genes (5%) were down-regulated. While in females, 9 dopaminergic (8%), 3 GABAergic (4%) and 6 glutamatergic (6%) synapse genes were downregulated. The data indicate that in both sexes the dopaminergic synapse was the most affected. In contrast, in control animals, no significant differences between male and female were present in these synapse genes. Since the most noticeable transcritpomic changes were found in the transcriptome of DA glutamatergic synapse, we investigated the expression of tyrosine-hydroxylase (TH) NMDA receptor subunits in the ARC. The western blot analyses and immunohistochemistry confirmed the sex-specific differences between prenatally betamethasone-exposed and saline-exposed P15 rats. Accordingly to the changes in gene expression, prenatal exposure to synthetic corticosteroids was associated with postnatal changes in behavior and susceptibility to certain types of seizures. While we did not find any significant impairements in normal behavioral patterns (open field activity), there was a sex-specific change in the novel object recognition test. We found that behavioral lateralization in females is lost after prenatal betamethasone exposure and both male and female prenatally betamethasone exposed rats were avoiding novelty. This trait is similar to children with autism and suggests that certain elements of autistic behaviors can be present after prenatal exposure to synthetic corticosteroids. Additionally, there were changes in the search patterns in the Morris water maze as well as in the Barnes maze. In conclusion, our work is consistent with findings of profound reprogramming changes in the brain after prenatal corticosteroid exposure associated with alterations cognitive functions and seizure susceptibility. Two-sexes (M, F) x two-condition (B = betamethasone prenataly exposed vs S = saline prenataly exposed) experiment. Biological replicates: 4 MS, 4 FS, 4 MB, 4 FB.

Project description:Background: How prenatal smoke exposure affects DNA methylation leading to atopic disorders remains to be addressed. Epigenetic biomarkers informative of prenatal smoke exposure and atopic disorders are wanting. Since most children suffering from atopic dermatitis (AD) continue to develop asthma later in life, we explored whether prenatal smoke exposure e induces DNA methylation and searched for predictive epigenetic biomarkers for smoke related atopic disorders. Methods: Methylation differences associated with smoke exposure were screened by Illumina methylation panel for children from the Taiwan birth panel study cohort initially. Information about development of atopic dermatitis (AD) and risk factors were collected. Cord blood cotinine levels were measured to represent prenatal smoke exposure. CpG loci that demonstrated a statistically significant difference in methylation were validated by methylation-dependent fragment separation (MDFS). Differential methylation in three genes (TSLP, GSTT1, and CYB5R3) was identified through the screen and their functions were investigated. Results: Among these, only thymic stromal lymphopoietin (TSLP) gene displayed significant difference in promoter methylation percentage after being validated by MDFS (p=0.029). TSLP gene was further investigated in a larger sample of 92 children from the cohort. Methylation status of the TSLP 5′-CpG island (CGI) was found to be significantly associated with prenatal smoke exposure (OR=3.59, 95%CI=1.49-8.64; cotinine level 0.10 ng/ml, sensitivity= 77%; specificity = 61%) and with AD (OR=4.77, 95%CI=1.47-15.53). The degree of TSLP 5′CGI methylation inversely correlated with TSLP protein expression levels (per unit: β=－6.69 ng/ml; 95% CIs, －12.80~－0.59; p=0.032). Conclusions: The effect of prenatal tobacco smoke exposure on the risk for AD may be mediated through DNA methylation. Cord blood methylated TSLP 5′CGI may be a potential epigenetic biomarker for environmentally-related atopic disorders. The buffy coat and plasma samples were separated and stored at −80°C. DNA (100 ng-500 ng) was extracted from cord white blood cells. Microarrays have been performed to investigate fourteen samples, which were classified as two groups according to cotinine exposure dosage (7 versus 7 : high exposure verses low exposure).

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Prenatal Pesticide Exposure Interacts with a Common Polymorphism in the PON1 Gene Leading to DNA Methylation Changes

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