title: Hyperglycemia impedes definitive endoderm differentiation of human embryonic stem cells by modulating histone methylation patterns.
abstract: Exposure to maternal diabetes during fetal growth is a risk factor for the development of type II diabetes (T2D) in later life. Discovery of the mechanisms involved in this association should provide valuable background for therapeutic treatments. Early embryogenesis involves epigenetic changes including histone modifications. The bivalent histone methylation marks H3K4me3 and H3K27me3 are important for regulating key developmental genes during early fetal pancreas specification. We hypothesized that maternal hyperglycemia disrupted early pancreas development through changes in histone bivalency. A human embryonic stem cell line (VAL3) was used as the cell model for studying the effects of hyperglycemia upon differentiation into definitive endoderm (DE), an early stage of the pancreatic lineage. Hyperglycemic conditions significantly down-regulated the expression levels of DE markers SOX17, FOXA2, CXCR4 and EOMES during differentiation. This was associated with retention of the repressive histone methylation mark H3K27me3 on their promoters under hyperglycemic conditions. The disruption of histone methylation patterns was observed as early as the mesendoderm stage, with Wnt/β-catenin signaling being suppressed during hyperglycemia. Treatment with Wnt/β-catenin signaling activator CHIR-99021 restored the expression levels and chromatin methylation status of DE markers, even in a hyperglycemic environment. The disruption of DE development was also found in mouse embryos at day 7.5 post coitum from diabetic mothers. Furthermore, disruption of DE differentiation in VAL3 cells led to subsequent impairment in pancreatic progenitor formation. Thus, early exposure to hyperglycemic conditions hinders DE development with a possible relationship to the later impairment of pancreas specification.
authors.affiliation: Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: A C H
authors.initials: ACH
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China. cherielee@hku.hk.|Shenzhen Key Laboratory of Fertility Regulation, The University of Hong Kong Shenzhen Hospital, The University of Hong Kong, Shenzhen, People's Republic of China. cherielee@hku.hk.|Center for Reproduction, Development and Growth, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China. cherielee@hku.hk.|Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Room 747, 21 Sassoon Road, Hong Kong, SAR, People's Republic of China. cherielee@hku.hk.
authors.forename: Y L
authors.initials: YL
authors.lastname: Lee
authors.affiliation: Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: S W
authors.initials: SW
authors.lastname: Fong
authors.affiliation: Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: C C Y
authors.initials: CCY
authors.lastname: Wong
authors.affiliation: Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.|Shenzhen Key Laboratory of Fertility Regulation, The University of Hong Kong Shenzhen Hospital, The University of Hong Kong, Shenzhen, People's Republic of China.|Center for Reproduction, Development and Growth, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: E H Y
authors.initials: EHY
authors.lastname: Ng
authors.affiliation: Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.|Shenzhen Key Laboratory of Fertility Regulation, The University of Hong Kong Shenzhen Hospital, The University of Hong Kong, Shenzhen, People's Republic of China.|Center for Reproduction, Development and Growth, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: W S B
authors.initials: WSB
authors.lastname: Yeung
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D001374:Azacitidine / Q000494:pharmacology; D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004707:Endoderm / Q000166:cytology* / Q000378:metabolism; D000071221:Enhancer of Zeste Homolog 2 Protein / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005947:Glucose / Q000494:pharmacology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000196:embryology* / Q000378:metabolism; D008297:Male; D008648:Mesoderm / Q000378:metabolism; D008745:Methylation; D051379:Mice; D008813:Mice, Inbred ICR; D010179:Pancreas / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
chemical_list: D000943:Antigens, Differentiation; D004791:Enzyme Inhibitors; D006657:Histones; D051153:Wnt Proteins; D051176:beta Catenin; D015254:DNA Modification Methylases; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D005947:Glucose; D001374:Azacitidine
keywords: Chromatin methylation; Definitive endoderm; Hyperglycemia; Wnt/β-catenin signaling pathway; hESCs