Analysis of genomic DNA methylation levels in human placenta using liquid chromatography-electrospray ionization tandem mass spectrometry.
BACKGROUND
DNA-methylation is a common epigenetic tool which plays a crucial role in gene regulation and is essential for cell differentiation and embryonic development. The placenta is an important organ where gene activity can be regulated by epigenetic DNA modifications, including DNA methylation. This is of interest as, the placenta is the interface between the fetus and its environment, the mother. Exposure to environmental toxins and nutrition during pregnancy may alter DNA methylation of the placenta and subsequently placental function and as a result the phenotype of the offspring. The aim of this study was to develop a reliable method to quantify DNA methylation in large clinical studies. This will be a tool to analyze the degree of DNA methylation in the human placenta in relationship to clinical readouts.


METHODS
Liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI/MS/MS) technique was used for the quantification of the 5dmC/dG ratio in placentas from 248 healthy pregnancies. We were able to demonstrate that this method is a reliable and stable way to determine global placental DNA methylation in large clinical trials.


CONCLUSIONS
The degree of placental DNA methylation seen in our pilot study varies substantially from 2% to 5%. The clinical implications of this variation need to be demonstrated in adequately powered large studies.
Institute of Nutritional Science, Department of Experimental Nutritional Medicine, University of Potsdam, Potsdam, Germany.
Sulistyo Emantoko
SE
Dwi Putra
Corinna
C
Neuber
Christoph
C
Reichetzeder
Berthold
B
Hocher
Burkhard
B
Kleuser
D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000592:standards; D015331:Cohort Studies; D004247:DNA / Q000032:analysis* / Q000592:standards; D019175:DNA Methylation; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000032:analysis / Q000592:standards; D003849:Deoxyguanosine / Q000032:analysis / Q000592:standards; D005260:Female; D015894:Genome, Human; D006801:Humans; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D021241:Spectrometry, Mass, Electrospray Ionization / Q000592:standards
D003841:Deoxycytidine; D004247:DNA; C016569:5-methyldeoxycytidine; D003849:Deoxyguanosine