title: Physiological oxygen prevents frequent silencing of the DLK1-DIO3 cluster during human embryonic stem cells culture.
abstract: Genetic and epigenetic alterations are observed in long-term culture (>30 passages) of human embryonic stem cells (hESCs); however, little information is available in early cultures. Through a large-scale gene expression analysis between initial-passage hESCs (ihESCs, <10 passages) and early-passage hESCs (ehESCs, 20-30 passages) of 12 hESC lines, we found that the DLK1-DIO3 gene cluster was normally expressed and showed normal methylation pattern in ihESC, but was frequently silenced after 20 passages. Both the DLK1-DIO3 active status in ihESCs and the inactive status in ehESCs were inheritable during differentiation. Silencing of the DLK1-DIO3 cluster did not seem to compromise the multilineage differentiation ability of hESCs, but was associated with reduced DNA damage-induced apoptosis in ehESCs and their differentiated hepatocyte-like cell derivatives, possibly through attenuation of the expression and phosphorylation of p53. Furthermore, we demonstrated that 5% oxygen, instead of the commonly used 20% oxygen, is required for preserving the expression of the DLK1-DIO3 cluster. Overall, the data suggest that active expression of the DLK1-DIO3 cluster represents a new biomarker for epigenetic stability of hESCs and indicates the importance of using a proper physiological oxygen level during the derivation and culture of hESCs.
authors.affiliation: Institute of Reproductive & Stem Cell Engineering, Central South University, Changsha, China; Key Laboratory of Stem Cells and Reproductive Engineering, Ministry of Health, Changsha, China.
authors.forename: Pingyuan
authors.initials: P
authors.lastname: Xie
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.forename: Qi
authors.initials: Q
authors.lastname: Ouyang
authors.forename: Liang
authors.initials: L
authors.lastname: Hu
authors.forename: Yueqiu
authors.initials: Y
authors.lastname: Tan
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zhou
authors.forename: Bo
authors.initials: B
authors.lastname: Xiong
authors.forename: Qianjun
authors.initials: Q
authors.lastname: Zhang
authors.forename: Ding
authors.initials: D
authors.lastname: Yuan
authors.forename: Yi
authors.initials: Y
authors.lastname: Pan
authors.forename: Tiancheng
authors.initials: T
authors.lastname: Liu
authors.forename: Ping
authors.initials: P
authors.lastname: Liang
authors.forename: Guangxiu
authors.initials: G
authors.lastname: Lu
authors.forename: Ge
authors.initials: G
authors.lastname: Lin
mesh_terms: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D019175:DNA Methylation / Q000235:genetics*; D053595:Embryonic Stem Cells / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D007453:Iodide Peroxidase / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism; D062085:RNA, Long Noncoding / Q000235:genetics
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; C512941:DLK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D062085:RNA, Long Noncoding; C117274:iodothyronine deiodinase type III; D007453:Iodide Peroxidase; D010100:Oxygen
keywords: Apoptosis; DLK1-DIO3; Epigenetics; Human embryonic stem cell; Physiological oxygen