title: Regulation of glycan structures in murine embryonic stem cells: combined transcript profiling of glycan-related genes and glycan structural analysis.
abstract: The abundance and structural diversity of glycans on glycoproteins and glycolipids are highly regulated and play important roles during vertebrate development. Because of the challenges associated with studying glycan regulation in vertebrate embryos, we have chosen to study mouse embryonic stem (ES) cells as they differentiate into embryoid bodies (EBs) or into extraembryonic endodermal (ExE) cells as a model for cellular differentiation. We profiled N- and O-glycan structures isolated from these cell populations and examined transcripts encoding the corresponding enzymatic machinery for glycan biosynthesis in an effort to probe the mechanisms that drive the regulation of glycan diversity. During differentiation from mouse ES cells to either EBs or ExE cells, general trends were detected. The predominance of high mannose N-glycans in ES cells shifted to an equal abundance of complex and high mannose structures, increased sialylation, and increased α-Gal termination in the differentiated cell populations. Whereas core 1 O-glycan structures predominated in all three cell populations, increased sialylation and increased core diversity characterized the O-glycans of both differentiated cell types. Increased polysialylation was also found in both differentiated cell types. Differences between the two differentiated cell types included greater sialylation of N-glycans in EBs, whereas α-Gal-capped structures were more prevalent in ExE cells. Changes in glycan structures generally, but not uniformly, correlated with alterations in transcript abundance for the corresponding biosynthetic enzymes, suggesting that transcriptional regulation contributes significantly to the regulation of glycan expression. Knowledge of glycan structural diversity and transcript regulation should provide greater understanding of the roles of protein glycosylation in vertebrate development.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Alison V
authors.initials: AV
authors.lastname: Nairn
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Aoki
authors.forename: Mitche
authors.initials: M
authors.lastname: dela Rosa
authors.forename: Mindy
authors.initials: M
authors.lastname: Porterfield
authors.forename: Jae-Min
authors.initials: JM
authors.lastname: Lim
authors.forename: Michael
authors.initials: M
authors.lastname: Kulik
authors.forename: J Michael
authors.initials: JM
authors.lastname: Pierce
authors.forename: Lance
authors.initials: L
authors.lastname: Wells
authors.forename: Stephen
authors.initials: S
authors.lastname: Dalton
authors.forename: Michael
authors.initials: M
authors.lastname: Tiemeyer
authors.forename: Kelley W
authors.initials: KW
authors.lastname: Moremen
mesh_terms: D000818:Animals; D053898:Biosynthetic Pathways / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D016000:Cluster Analysis; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D058732:Embryoid Bodies / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000378:metabolism*; D004707:Endoderm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D018507:Gene Expression Regulation, Developmental; D054794:Glycomics / Q000379:methods; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D008856:Microscopy, Fluorescence; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059467:Transcriptome / Q000235:genetics*
chemical_list: D011134:Polysaccharides