Methylation Status of Imprinting Centers for H19/IGF2 and SNURF/SNRPN in Primate Embryonic Stem Cells

¹ Division of Reproductive Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon
² Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
³ Department of Obstetrics & Gynecology, Faculty of Medicine, University of Tokyo, Tokyo, Japan

^* To whom correspondence should be addressed. E-mail: mitalipo{at}ohsu.edu.

	Abstract

Embryonic stem cells (ESCs) hold promise for cell and tissue replacement approaches to treating human diseases based on their capacity to differentiate into a wide variety of somatic cells and tissues. However, long-term in vitro culture and manipulations of ESCs may adversely affect their epigenetic integrity including imprinting. We have recently reported aberrant biallelic expression of IGF2 and H19 in several rhesus monkey ESC lines while SNRPN and NDN were normally imprinted and expressed predominantly from the paternal allele. The disregulation of IGF2 and H19 that is associated with tumorigenesis in humans may result from improper maintenance of allele-specific methylation patterns at an imprinting center (IC) upstream of H19. To test this possibility, we performed methylation analysis of several monkey ESC lines by genomic bisulfite sequencing. We investigated methylation profiles of CpG islands within the IGF2/H19 IC harboring the CTCF-6 binding site. Additionally, the methylation status of the IC within the promoter/exon 1 of SNURF/SNRPN known as the Prader-Willi syndrome IC was examined. Our results demonstrate abnormal hypermethylation within the IGF2/H19 IC in all analyzed ESC lines, while the SNURF/SNRPN IC was differentially methylated consistent with monoallelic expression.