title: Developmental regulation of trigeminal TRPA1 by the cornea.
abstract: OBJECTIVE
  The cornea is densely innervated with nociceptive nerves that detect deleterious stimuli at the ocular surface and transduce these stimuli as sensations of pain. Thus, nociception is a major factor involved in preventing damage to corneal tissues. One class of molecules that is thought to be involved in detecting such stimuli is the transient receptor potential (TRP) family of ion channels. However, little is known about the acquisition of these channels during corneal development. Therefore, the present study examined the developmental acquisition of these receptors and elucidated certain parameters involved in this acquisition.
  
  
  METHODS
  Quantitative RT-PCR was used to measure the expression of genes including TRPA and Ret in vivo. In vitro cocultures between cornea and the ophthalmic lobe of the trigeminal ganglion were used to test interactions between nerves and corneas along with recombinant proteins.
  
  
  RESULTS
  TRPA1 mRNA showed a progressive temporal increase in the ophthalmic lobe of the trigeminal ganglion in vivo during embryonic development. In vitro, TRPA1 expression was significantly increased in the ganglion when cocultured with cornea, compared to ganglia cultured alone. Similarly, the addition of exogenous neurotrophin-3 (NT3) protein to cultured ganglia increased the expression of TRPA1 more than 100-fold. Addition of NT3 and neurturin synergistically increased TRPA1 expression in embryonic day (E)8 ganglia, but this effect was lost at E12. At E8, Ret+ nonpeptidergic neurons are specified in the trigeminal ganglion.
  
  
  CONCLUSIONS
  Corneal-derived factors increase TRPA1 expression in trigeminal nonpeptidergic neurons during their embryonic specification.
authors.affiliation: Program in Cell, Molecular and Developmental Biology, Sackler School of Graduate Biomedical Sciences, Department of Integrated Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts, United States Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States.
authors.forename: James P
authors.initials: JP
authors.lastname: Canner
authors.affiliation: Program in Cell, Molecular and Developmental Biology, Sackler School of Graduate Biomedical Sciences, Department of Integrated Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts, United States.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Linsenmayer
authors.affiliation: Program in Cell, Molecular and Developmental Biology, Sackler School of Graduate Biomedical Sciences, Department of Integrated Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts, United States.
authors.forename: James K
authors.initials: JK
authors.lastname: Kubilus
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000096:biosynthesis / Q000235:genetics*; D002642:Chick Embryo; D003315:Cornea / Q000196:embryology / Q000294:innervation*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels / Q000096:biosynthesis / Q000235:genetics*; D012668:Trigeminal Ganglion / Q000196:embryology / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050051:Transient Receptor Potential Channels
keywords: TRPA1; corneal innervation; neurotrophin-3; nociception