title: PON1 as a model for integration of genetic, epigenetic, and expression data on candidate susceptibility genes.
abstract: Recent genome- and epigenome-wide studies demonstrate that the DNA methylation is controlled in part by genetics, highlighting the importance of integrating genetic and epigenetic data. To better understand molecular mechanisms affecting gene expression, we used the candidate susceptibility gene paraoxonase 1 (PON1) as a model to assess associations ofPON1genetic polymorphisms with DNA methylation and arylesterase activity, a marker ofPON1expression.PON1has been associated with susceptibility to obesity, cardiovascular disease, and pesticide exposure. In this study, we assessed DNA methylation in 18 CpG sites located alongPON1shores, shelves, and its CpG island in blood specimens collected from newborns and 9-year-old children participating (n= 449) in the CHAMACOS birth cohort study. The promoter polymorphism,PON1-108, was strongly associated with methylation, particularly for CpG sites located near the CpG island (P<< 0.0005). Among newborns, these relationships were even more pronounced after adjusting for blood cell composition. We also observed significant decreases in arylesterase activity with increased methylation at the same nine CpG sites at both ages. Using causal mediation analysis, we found statistically significant indirect effects of methylation (β(95% confidence interval): 6.9(1.5, 12.4)) providing evidence that DNA methylation mediates the relationship betweenPON1-108genotype andPON1expression. Our findings show that integration of genetic, epigenetic, and expression data can shed light on the functional mechanisms involving genetic and epigenetic regulation of candidate susceptibility genes likePON1.
authors.affiliation: School of Public Health, University of California, Berkeley, 50 University Hall #7360, Berkeley, CA 94720-7360, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Huen
authors.affiliation: School of Public Health, University of California, Berkeley, 50 University Hall #7360, Berkeley, CA 94720-7360, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Yousefi
authors.affiliation: School of Public Health, University of California, Berkeley, 50 University Hall #7360, Berkeley, CA 94720-7360, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Street
authors.affiliation: School of Public Health, University of California, Berkeley, 50 University Hall #7360, Berkeley, CA 94720-7360, USA.
authors.forename: Brenda
authors.initials: B
authors.lastname: Eskenazi
authors.affiliation: School of Public Health, University of California, Berkeley, 50 University Hall #7360, Berkeley, CA 94720-7360, USA.
authors.forename: Nina
authors.initials: N
authors.lastname: Holland
keywords: arylesterase; mediation; methylation; paraoxonase