title: Sodium-dependent vitamin C transporter-2 mediates vitamin C transport at the cortical nerve terminal.
abstract: It has been shown that vitamin C (VC) is transported at synaptic boutons, but how this occurs has not been elucidated. This study investigates the role of the sodium-dependent vitamin C transporter-2 (SVCT2) in transporting VC at the cortical nerve terminal. Immunostaining of cultured mouse superior cervical ganglion cells showed the SVCT2 to be expressed in presynaptic boutons, colocalizing with the vesicular monoamine transporter-2 and the norepinephrine transporter. Immunoblotting of enriched cortical synaptosomes demonstrated that the SVCT2 was enriched in presynaptic fractions, confirming a predominantly presynaptic location. In crude synaptosomes, known inhibitors of SVCT2 inhibited uptake of VC. Furthermore, the kinetic features of VC uptake were consistent with SVCT2-mediated function. VC was also found to efflux from synaptosomes by a mechanism not involving the SVCT2. Indeed, VC efflux was substantially offset by reuptake of VC on the SVCT2. The presence and function of the SVCT2 at the presynaptic nerve terminal suggest that it is the transporter responsible for recovery of VC released into the synaptic cleft.
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.
authors.forename: Marquicia R
authors.initials: MR
authors.lastname: Pierce
authors.affiliation: Department of Neuroscience, Vanderbilt University, Nashville, Tennessee.
authors.forename: Amita
authors.initials: A
authors.lastname: Raj
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Betke
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee.
authors.forename: L Nora
authors.initials: LN
authors.lastname: Zeidan
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.
authors.forename: Heinrich J G
authors.initials: HJ
authors.lastname: Matthies
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee.
authors.forename: James M
authors.initials: JM
authors.lastname: May
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001205:Ascorbic Acid / Q000378:metabolism*; D001572:Benzofurans / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D000076122:Disks Large Homolog 4 Protein; D051528:Guanylate Kinases / Q000378:metabolism; D007093:Imidazoles / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D060347:Sodium-Coupled Vitamin C Transporters / Q000378:metabolism*; D017783:Superior Cervical Ganglion / Q000166:cytology; D013574:Synaptosomes / Q000378:metabolism; D050493:Vesicular Monoamine Transport Proteins / Q000378:metabolism
chemical_list: D001572:Benzofurans; D002247:Carbon Isotopes; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D007093:Imidazoles; D008565:Membrane Proteins; D050484:Norepinephrine Plasma Membrane Transport Proteins; C493453:Slc18a2 protein, mouse; C555165:Slc23a2 protein, mouse; D060347:Sodium-Coupled Vitamin C Transporters; D050493:Vesicular Monoamine Transport Proteins; C082877:fura red; D012964:Sodium; D051528:Guanylate Kinases; D001205:Ascorbic Acid
keywords: antioxidant; cortical neurons; ganglia; membrane transport; synaptosome