title: ST8SIA4-Dependent Polysialylation is Part of a Developmental Program Required for Germ Layer Formation from Human Pluripotent Stem Cells.
abstract: Polysialic acid (PSA) is a carbohydrate polymer of repeating α-2,8 sialic acid residues that decorates multiple targets, including neural cell adhesion molecule (NCAM). PST and STX encode the two enzymes responsible for PSA modification of target proteins in mammalian cells, but despite widespread polysialylation in embryonic development, the majority of studies have focused strictly on the role of PSA in neurogenesis. Using human pluripotent stem cells (hPSCs), we have revisited the developmental role of PST and STX and show that early progenitors of the three embryonic germ layers are polysialylated on their cell surface. Changes in polysialylation can be attributed to lineage-specific expression of polysialyltransferase genes; PST is elevated in endoderm and mesoderm, while STX is elevated in ectoderm. In hPSCs, PST and STX genes are epigenetically marked by overlapping domains of H3K27 and H3K4 trimethylation, indicating that they are held in a "developmentally-primed" state. Activation of PST transcription during early mesendoderm differentiation is under control of the T-Goosecoid transcription factor network, a key regulatory axis required for early cell fate decisions in the vertebrate embryo. This establishes polysialyltransferase genes as part of a developmental program associated with germ layer establishment. Finally, we show by shRNA knockdown and CRISPR-Cas9 genome editing that PST-dependent cell surface polysialylation is essential for endoderm specification. This is the first report to demonstrate a role for a glycosyltransferase in hPSC lineage specification. Stem Cells 2016;34:1742-1752.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Georgia, Athens, Georgia, USA.|Center for Molecular Medicine, The University of Georgia, Athens, Georgia, USA.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Berger
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Georgia, Athens, Georgia, USA.|Center for Molecular Medicine, The University of Georgia, Athens, Georgia, USA.
authors.forename: Yu Hua
authors.initials: YH
authors.lastname: Sun
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Georgia, Athens, Georgia, USA.|Center for Molecular Medicine, The University of Georgia, Athens, Georgia, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Kulik
authors.affiliation: Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA.
authors.forename: Jin Kyu
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA.
authors.forename: Alison V
authors.initials: AV
authors.lastname: Nairn
authors.affiliation: Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA.
authors.forename: Kelley W
authors.initials: KW
authors.lastname: Moremen
authors.affiliation: Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Pierce
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Georgia, Athens, Georgia, USA.|Center for Molecular Medicine, The University of Georgia, Athens, Georgia, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Dalton
mesh_terms: D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D002462:Cell Membrane / Q000378:metabolism; D004707:Endoderm / Q000166:cytology / Q000378:metabolism; D005855:Germ Layers / Q000378:metabolism*; D006801:Humans; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism*; D012794:Sialic Acids / Q000378:metabolism*; D012799:Sialyltransferases / Q000378:metabolism*; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D012794:Sialic Acids; D014157:Transcription Factors; C021319:polysialic acid; D012799:Sialyltransferases; C515117:ST8SIA4 protein, human
keywords: Glycosylation; Neural cell adhesion molecule; Pluripotent stem cells; Polysialic acid