title: In vitro lead exposure changes DNA methylation and expression of IGF2 and PEG1/MEST.
abstract: Epigenetic processes, such as changes in DNA methylation, likely mediate the link between environmental exposures in utero and altered gene expression. Differentially methylated regions (DMRs) that regulate imprinted genes may be especially vulnerable to environmental exposures since imprinting is established and maintained largely through DNA methylation, resulting in expression from only one parental chromosome. We used the human embryonic kidney cell line, HEK-293, to investigate the effects of exposure to physiologically relevant doses of lead acetate (Pb) on the methylation status of nine imprinted gene DMRs. We assessed mean methylation after seventy-two hours of Pb exposure (0-25 μg/dL) using bisulfite pyrosequencing. The PEG1/MEST and IGF2 DMRs had maximum methylation decreases of 9.6% (20 μg/dL; p<0.005) and 3.8% (25 μg/dL; p<0.005), respectively. Changes at the MEG3 DMRs had a maximum decrease in methylation of 2.9% (MEG3) and 1.8% (MEG3-IG) at 5 μg/dL Pb, but were not statistically significant. The H19, NNAT, PEG3, PLAGL1, and SGCE/PEG10 DMRs showed a less than 0.5% change in methylation, across the dose range used, and were deemed non-responsive to Pb in our model. Pb exposure below reportable/actionable levels increased expression of PEG1/MEST concomitant with decreased methylation. These results suggest that Pb exposure can stably alter the regulatory capacity of multiple imprinted DMRs.
authors.affiliation: Duke University Medical Center, Department of Obstetrics and Gynecology, B225 LSRC, Research Drive, Durham, NC 27708, USA; University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, 450 West Drive, Chapel Hill, NC 27599, USA. Electronic address: mnye@email.unc.edu.
authors.forename: Monica D
authors.initials: MD
authors.lastname: Nye
authors.affiliation: Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA. Electronic address: choyo@ncsu.edu.
authors.forename: Cathrine
authors.initials: C
authors.lastname: Hoyo
authors.affiliation: Duke University Medical Center, Department of Obstetrics and Gynecology, B225 LSRC, Research Drive, Durham, NC 27708, USA. Electronic address: susan.murphy@duke.edu.
authors.forename: Susan K
authors.initials: SK
authors.lastname: Murphy
mesh_terms: D019175:DNA Methylation / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis* / Q000235:genetics; D007854:Lead / Q000633:toxicity*; D009942:Organometallic Compounds / Q000633:toxicity; D011506:Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D009942:Organometallic Compounds; D011506:Proteins; C103637:mesoderm specific transcript protein; D007854:Lead; D007335:Insulin-Like Growth Factor II; C008261:lead acetate
keywords: Bisulfite pyrosequencing; DNA methylation; Epigenetics; Insulin-like growth factor 2 (IGF2); Lead acetate; Paternally expressed gene 1/mesoderm specific transcript (PEG1/MEST)