The human placenta methylome

Diane I. Schroeder, John D. Blair, Paul Lott, Hung On Ken Yu, Danna Hong, Florence Crary, Paul Ashwood, Cheryl Walker, Ian F Korf, Wendy P. Robinson, Janine M LaSalle

Research output: Contribution to journalArticle

128 Citations (Scopus)

Abstract

Tissue-specific DNA methylation is found at promoters, enhancers, and CpG islands but also over larger genomic regions. In most human tissues, the vast majority of the genome is highly methylated (>70%). Recently, sequencing of bisulfite-treated DNA (MethylC-seq) has revealed large partially methylated domains (PMDs) in some human cell lines. PMDs cover up to 40% of the genome and are associated with gene repression and inactive chromatin marks. However, to date, only cultured cells and cancers have shown evidence for PMDs. Here, we performed MethylC-seq in full-term human placenta and demonstrate it is the first known normal tissue showing clear evidence of PMDs. We found that PMDs cover 37% of the placental genome, are stable throughout gestation and between individuals, and can be observed with lower sensitivity in Illumina 450K Infinium data. RNA-seq analysis confirmed that genes in PMDs are repressed in placenta. Using a hidden Markov model to map placental PMDs genome-wide and compare them to PMDs in other cell lines, we found that genes within placental PMDs have tissuespecific functions. For regulatory regions, methylation levels in promoter CpG islands are actually higher for genes within placental PMDs, despite the lower overall methylation of surrounding regions. Similar to PMDs, polycomb-regulated regions are hypomethylated but smaller and distinct from PMDs, with some being hypermethylated in placenta compared with other tissues. These results suggest that PMDs are a developmentally dynamic feature of the methylome that are relevant for understanding both normal development and cancer and may be of use as epigenetic biomarkers.

Original languageEnglish (US)
Pages (from-to)6037-6042
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Issue number15
DOIs
StatePublished - Apr 9 2013

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Placenta
Genome
CpG Islands
Methylation
Genes
Cell Line
Nucleic Acid Regulatory Sequences
DNA Methylation
Epigenomics
Chromatin
Cultured Cells
Neoplasms
Biomarkers
RNA
Pregnancy
DNA

Keywords

  • Epigenomics
  • Hypomethylation

ASJC Scopus subject areas

  • General

Cite this

The human placenta methylome. / Schroeder, Diane I.; Blair, John D.; Lott, Paul; Yu, Hung On Ken; Hong, Danna; Crary, Florence; Ashwood, Paul; Walker, Cheryl; Korf, Ian F; Robinson, Wendy P.; LaSalle, Janine M.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 110, No. 15, 09.04.2013, p. 6037-6042.

Research output: Contribution to journalArticle

Schroeder, DI, Blair, JD, Lott, P, Yu, HOK, Hong, D, Crary, F, Ashwood, P, Walker, C, Korf, IF, Robinson, WP & LaSalle, JM 2013, 'The human placenta methylome', Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 15, pp. 6037-6042. https://doi.org/10.1073/pnas.1215145110
Schroeder, Diane I. ; Blair, John D. ; Lott, Paul ; Yu, Hung On Ken ; Hong, Danna ; Crary, Florence ; Ashwood, Paul ; Walker, Cheryl ; Korf, Ian F ; Robinson, Wendy P. ; LaSalle, Janine M. / The human placenta methylome. In: Proceedings of the National Academy of Sciences of the United States of America. 2013 ; Vol. 110, No. 15. pp. 6037-6042.
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