title: Expression Profiling of Ascorbic Acid-Related Transporters in Human and Mouse Eyes.
abstract: OBJECTIVE
  Ascorbic acid (AsA) is an important antioxidant in the eye. Ascorbic acid is usually transported by sodium-dependent AsA transporters (SVCTs), and dehydroascorbic acid (DHA) by glucose transporters (GLUTs). This study investigates these AsA-related transporters in human compared with mouse eyes.
  
  
  METHODS
  Five pairs of human donor eyes and 15 pairs of mouse eyes were collected. Immunofluorescence and in situ hybridization were performed to detect SVCTs and GLUTs expression in the ciliary epithelium, retina, and lens epithelial cells (LECs). These tissues were isolated with laser microdissection followed by extraction of total RNA. Quantitative PCR (qPCR) was performed to examine the mRNA level of SVCTs and GLUTs in human and mouse ocular tissues.
  
  
  RESULTS
  Immunofluorescence and in situ hybridization showed SVCT2 and GLUT1 expression in human ciliary epithelium with varied distributions. Sodium-dependent AsA transporter 2 is expressed only in the pigmented epithelium (PE), and GLUT1 is predominately expressed in the nonpigmented epithelium (NPE). However, SVCT2 was not identified in mouse ciliary epithelium, whereas GLUT1 expressed in both PE and NPE. Laser microdissection and qPCR revealed high levels of SVCT2 mRNA in human RPE cells and murine neural retina. Sodium-dependent AsA transporter 1 mRNA could be detected only in human and murine LECs. Glucose transporter 3 and GLUT4 mRNA could not be detected in either the human or mouse ciliary processes or in the lens epithelium.
  
  
  CONCLUSIONS
  These fundamental findings indicate AsA transporter expression in eyes of humans is significantly different compared with mice. This may explain why human aqueous and vitreous humors contain higher AsA levels compared with other animals.
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States 2Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Ma
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Carla
authors.initials: C
authors.lastname: Siegfried
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States 3Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kubota
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Margaret
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Belinda
authors.initials: B
authors.lastname: Dana
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Andrew
authors.initials: A
authors.lastname: Huang
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: David
authors.initials: D
authors.lastname: Beebe
authors.affiliation: Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yan
authors.affiliation: Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States.
authors.forename: Ying-Bo
authors.initials: YB
authors.lastname: Shui
mesh_terms: D000818:Animals; D001205:Ascorbic Acid; D001692:Biological Transport; D002924:Ciliary Body / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D051272:Glucose Transporter Type 1 / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D007908:Lens, Crystalline / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000378:metabolism; D060347:Sodium-Coupled Vitamin C Transporters / Q000378:metabolism*
chemical_list: D051272:Glucose Transporter Type 1; D012333:RNA, Messenger; C555163:SLC23A2 protein, human; D060347:Sodium-Coupled Vitamin C Transporters; D001205:Ascorbic Acid