title: Cell surface labeling and mass spectrometry reveal diversity of cell surface markers and signaling molecules expressed in undifferentiated mouse embryonic stem cells.
abstract: Although interactions between cell surface proteins and extracellular ligands are key to initiating embryonic stem cell differentiation to specific cell lineages, the plasma membrane protein components of these cells are largely unknown. We describe here a group of proteins expressed on the surface of the undifferentiated mouse embryonic stem cell line D3. These proteins were identified using a combination of cell surface labeling with biotin, subcellular fractionation of plasma membranes, and mass spectrometry-based protein identification technology. From 965 unique peptides carrying biotin labels, we assigned 324 proteins including 235 proteins that have putative signal sequences and/or transmembrane segments. Receptors, transporters, and cell adhesion molecules were the major classes of proteins identified. Besides known cell surface markers of embryonic stem cells, such as alkaline phosphatase, the analysis identified 59 clusters of differentiation-related molecules and more than 80 components of multiple cell signaling pathways that are characteristic of a number of different cell lineages. We identified receptors for leukemia-inhibitory factor, interleukin 6, and bone morphogenetic protein, which play critical roles in the maintenance of undifferentiated mouse embryonic stem cells. We also identified receptors for growth factors/cytokines, such as fibroblast growth factor, platelet-derived growth factor, ephrin, Hedgehog, and Wnt, which transduce signals for cell differentiation and embryonic development. Finally we identified a variety of integrins, cell adhesion molecules, and matrix metalloproteases. These results suggest that D3 cells express diverse cell surface proteins that function to maintain pluripotency, enabling cells to respond to various external signals that initiate differentiation into a variety of cell types.
authors.affiliation: Division of Proteomics Research, Institute of Medical Science, Graduate School of Frontier Sciences, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nunomura
authors.forename: Kohji
authors.initials: K
authors.lastname: Nagano
authors.forename: Chiharu
authors.initials: C
authors.lastname: Itagaki
authors.forename: Masato
authors.initials: M
authors.lastname: Taoka
authors.forename: Nobuko
authors.initials: N
authors.lastname: Okamura
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamauchi
authors.forename: Sumio
authors.initials: S
authors.lastname: Sugano
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Takahashi
authors.forename: Tomonori
authors.initials: T
authors.lastname: Izumi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Isobe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001331:Automation; D001483:Base Sequence; D015415:Biomarkers / Q000032:analysis; D019921:Biotinylation; D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane / Q000648:ultrastructure*; D017931:DNA Primers; D004622:Embryo, Mammalian; D013058:Mass Spectrometry / Q000379:methods; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D051379:Mice; D010446:Peptide Fragments / Q000737:chemistry; D015398:Signal Transduction; D013234:Stem Cells / Q000502:physiology / Q000648:ultrastructure*
chemical_list: D015415:Biomarkers; D017931:DNA Primers; D008565:Membrane Proteins; D010446:Peptide Fragments