title: Conversion of genomic imprinting by reprogramming and redifferentiation.
abstract: Induced pluripotent stem cells (iPSCs), generated from somatic cells by overexpression of transcription factors Oct4, Sox2, Klf4 and c-Myc have the same characteristics as pluripotent embryonic stem cells (ESCs). iPSCs reprogrammed from differentiated cells undergo epigenetic modification during reprogramming, and ultimately acquire a similar epigenetic state to that of ESCs. In this study, these epigenetic changes were observed in reprogramming of uniparental parthenogenetic somatic cells. The parthenogenetic pattern of imprinted genes changes during the generation of parthenogenetic maternal iPSCs (miPSCs), a process referred to as pluripotent reprogramming. We determined whether altered imprinted genes are maintained or revert to the parthenogenetic state when the reprogrammed cells are redifferentiated into specialized cell types. To address this question, we redifferentiated miPSCs into neural stem cells (miPS-NSCs) and compared them with biparental female NSCs (fNSCs) and parthenogenetic NSCs (pNSCs). We found that pluripotent reprogramming of parthenogenetic somatic cells could reset parthenogenetic DNA methylation patterns in imprinted genes, and that alterations in DNA methylation were maintained even after miPSCs were redifferentiated into miPS-NSCs. Notably, maternally methylated imprinted genes (Peg1, Peg3, Igf2r, Snrpn and Ndn), whose differentially methylated regions were fully methylated in pNSCs, were demethylated and their expression levels were found to be close to the levels in normal biparental fNSCs after reprogramming and redifferentiation. Our findings suggest that pluripotent reprogramming of parthenogenetic somatic cells followed by redifferentiation leads to changes in DNA methylation of imprinted genes and the reestablishment of gene expression levels to those of normal biparental cells.
authors.affiliation: Department of Animal Biotechnology, College of Animal Bioscience and Technology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 133-702, Republic of Korea.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Hyun Woo
authors.initials: HW
authors.lastname: Choi
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Jang
authors.forename: Hyung Min
authors.initials: HM
authors.lastname: Chung
authors.forename: Marcos J
authors.initials: MJ
authors.lastname: Arauzo-Bravo
authors.forename: Hans R
authors.initials: HR
authors.lastname: Schöler
authors.forename: Jeong Tae
authors.initials: JT
authors.lastname: Do
mesh_terms: D000818:Animals; D054337:Cell Dedifferentiation; D019175:DNA Methylation; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D018392:Genomic Imprinting; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*; D000090062:Kruppel-Like Factor 4; D051379:Mice; D008817:Mice, Mutant Strains; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D014157:Transcription Factors
keywords: Imprinted genes; Induced pluripotent stem cells; Parthenogenetic cells; Reprogramming