title: Expression patterns of glycine transporters (xGlyT1, xGlyT2, and xVIAAT) in Xenopus laevis during early development.
abstract: Glycine, a major inhibitory neurotransmitter in the vertebrate nervous system, not only functions in synaptic signaling, but has also been implicated in regulating neuronal differentiation, neuronal proliferation, synaptic modeling, and neural network stability. Elements of the glycinergic phenotype include the membrane-bound glycine transporters (GLYT1 and GLYT2), which remove glycine from the synaptic cleft, and the vesicular inhibitory amino acid transporter (VIAAT or VGAT), which sequesters both glycine and GABA into synaptic vesicles. Here, we describe the spatial and temporal expression patterns of xGlyT1, xGlyT2, and xVIAAT during early developmental stages of Xenopus laevis. In situ hybridization reveals that xGlyT1 is first expressed in early tailbud stages in the midbrain, hindbrain, and anterior spinal cord; it extends posteriorly through the spinal cord and appears in the forebrain, retina, between the somites, and in the blood islands by swimming tadpole stages. xGlyT2 and xVIAAT initially appear in late neurula stages in the anterior spinal cord. By swimming tadpole stages, the expression of these genes appears in the forebrain, midbrain, and hindbrain and extends posteriorly through the spinal cord; xVIAAT is also expressed in the retina. Confocal analysis of multiplex fluorescent in situ hybridization signal in the spinal cord reveals that xGlyT1 and xGlyT2 share little cellular colocalization. While there is significant coexpression between xVIAAT and xGlyT2, xVIAAT and the GABAergic marker glutamic acid decarboxylase (xGAD67), and xGlyT2 and xGAD67, each gene also appears to have discrete, non-colocalized areas of expression.
authors.affiliation: Department of Biology, The College of William and Mary, Millington Hall, Landrum Drive, Williamsburg, VA 23185, United States.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Wester
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Teasley
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Byers
authors.forename: Margaret S
authors.initials: MS
authors.lastname: Saha
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D015870:Gene Expression; D050487:Glycine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020539:Sequence Analysis, Protein; D050495:Vesicular Inhibitory Amino Acid Transport Proteins / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: C529164:GlyT1 protein, Xenopus; D050487:Glycine Plasma Membrane Transport Proteins; D012333:RNA, Messenger; C529165:SLC6A5 protein, Xenopus; C529166:VIAAT protein, Xenopus; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D029867:Xenopus Proteins