title: The amino acid transporter SNAT2 mediates L-proline-induced differentiation of ES cells.
abstract: There is an increasing appreciation that amino acids can act as signaling molecules in the regulation of cellular processes through modulation of intracellular cell signaling pathways. In culture, embryonic stem (ES) cells can be differentiated to a second, pluripotent cell population, early primitive ectoderm-like cells in response to biological activities within the conditioned medium MEDII. The amino acid l-proline has been identified as a component of MEDII required for ES cell differentiation. Here, we define the primary l-proline transporter on ES and early primitive ectoderm-like cells as sodium-coupled neutral amino acid transporter 2 (SNAT2). SNAT2 uptake of l-proline can be inhibited by the addition of millimolar concentrations of other substrates. The addition of excess amino acids was used to regulate the uptake of l-proline by ES cells, and the effect on differentiation was analyzed. The ability of SNAT2 substrates, but not other amino acids, to prevent changes in morphology, gene expression, and differentiation kinetics suggested that l-proline uptake through SNAT2 was required for ES cell differentiation. These data reveal an unexpected role for amino acid uptake and the amino acid transporter SNAT2 in regulation of pluripotent cells in culture and provides a number of specific, inexpensive, and nontoxic culture additives with the potential to improve the quality of ES cell culture.
authors.affiliation: Dept. of Zoology, University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Boon Siang Nicholas
authors.initials: BS
authors.lastname: Tan
authors.forename: Ana
authors.initials: A
authors.lastname: Lonic
authors.forename: Michael B
authors.initials: MB
authors.lastname: Morris
authors.forename: Peter D
authors.initials: PD
authors.lastname: Rathjen
authors.forename: Joy
authors.initials: J
authors.lastname: Rathjen
mesh_terms: D026924:Amino Acid Transport System A / Q000235:genetics / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D004622:Embryo, Mammalian / Q000502:physiology; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D051379:Mice; D011392:Proline / Q000378:metabolism*
chemical_list: D026924:Amino Acid Transport System A; D000596:Amino Acids; D017077:Culture Media, Conditioned; C498798:Slc38a2 protein, mouse; D011392:Proline