title: Down-Regulation of RNA 3'-Terminal Phosphate Cyclase Attenuates Toll-Like Receptor 3-Mediated Axonal Loss in the Retina and Optic Nerve.
abstract: OBJECTIVE
  To investigate the role of RNA 3'-terminal phosphate cyclase (Rtca) in Toll-like receptor 3 (TLR3)-mediated loss of retinal ganglion cells (RGCs) and their axons.
  
  
  METHODS
  Polyinosinic-polycytidylic acid (Poly[I:C]) or PBS was injected into the vitreous humor of C57BL/6J and Tlr3 knockout mice. C57BL/6J mouse eyes were treated with Rtca silencing RNA or control RNA, with or without PBS or Poly(I:C). At 24, 48, and 72 hours after treatments, RGC loss was determined with the brain-specific homeobox/POU domain protein 3a antibody, and axonal loss was assessed by using the neuronal class III beta-tubulin (Tuj1) antibody. Axonal loss in the optic nerves was determined by anterograde-labeling of Cholera Toxin B. Western blot assays were performed to determine TLR3, Rtca, c-jun N-terminal kinase 3 (JNK3), and phospho-JNK3 (pJNK3) levels, and immunohistochemistry assays were performed to determine the cells that synthesize Rtca.
  
  
  RESULTS
  Poly(I:C) significantly up-regulated the protein levels of TLR3, Rtca, JNK3, and pJNK3 in the retina. Rtca levels were increased in RGCs, and an increase in Rtca levels promoted significant loss of RGCs and their axons. In Tlr3 knockout mouse retinas, Poly(I:C) failed to elevate Rtca, JNK3, and pJNK3 protein levels and did not promote significant axonal loss. Also, Rtca silencing RNA down-regulated Rtca, JNK3, and pJNK3 in C57BL/6J mouse retinas, and down-regulation of Rtca attenuated Poly(I:C)-mediated loss of RGCs and their axons.
  
  
  CONCLUSIONS
  The results presented in this study show that the activation of TLR3 promotes the loss of RGCs and their axons by elevating Rtca levels in the retina. Also, the results presented in this study show that Rtca regulates JNK3 expression in the retina.
authors.affiliation: Laboratory of Ophthalmic Neurobiology, Eye Research Institute of Oakland University, Rochester, Michigan, United States.
authors.forename: Shravan K
authors.initials: SK
authors.lastname: Chintala
authors.affiliation: Laboratory of Ophthalmic Neurobiology, Eye Research Institute of Oakland University, Rochester, Michigan, United States.
authors.forename: Naveena
authors.initials: N
authors.lastname: Daram
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000473:pathology; D015153:Blotting, Western; D004195:Disease Models, Animal; D015536:Down-Regulation; D007150:Immunohistochemistry; D008025:Ligases / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009900:Optic Nerve / Q000000981:diagnostic imaging / Q000378:metabolism*; D012313:RNA / Q000235:genetics*; D012162:Retinal Degeneration / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology*; D051196:Toll-Like Receptor 3 / Q000096:biosynthesis / Q000235:genetics*
chemical_list: C519703:TLR3 protein, mouse; D051196:Toll-Like Receptor 3; D012313:RNA; D008025:Ligases; C037451:RNA 3'-terminal phosphate cyclase