Retinal G-substrate, potential downstream component of NO/cGMP/PKG pathway, is located in subtype of retinal ganglion cells and amacrine cells with protein phosphatases

Brain Res Mol Brain Res. 2005 Apr 27;135(1-2):58-68. doi: 10.1016/j.molbrainres.2004.12.006.

Abstract

The aim of this study was to determine the distribution and function of G-substrate, a specific substrate of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-cGMP-dependent protein kinase (PKG) signaling pathway, in normal rat retina and in G-substrate knockout mice. The retinas of adult wild-type rats and mice and G-substrate knockout mice were studied immunohistologically to characterize the upstream and downstream components of the NO-cGMP-PKG pathway. Immunoblot analysis showed that the molecular weight of retinal G-substrate was similar to that of cerebellar G-substrate. In adult rats and mice, retinal G-substrate was located in a subpopulation of amacrine cells and in C38-positive retinal ganglion cells (RGCs) but not in alpha RGCs. In addition, retinal G-substrate was co-expressed with other upstream and downstream signaling components of the NO-cGMP-PKG-G-substrate-phosphatase pathway in the adult retina. Electroretinographic (ERG) analysis demonstrated that there was no significant difference between the ERGs of wild-type and G-substrate knockout mice. These results suggest that retinal G-substrate plays a role as a downstream component of the NO-cGMP-PKG pathway. The co-localization of retinal G-substrate with protein Ser/Thr phosphatases suggests that it acts as an endogenous protein phosphatase inhibitor as in the cerebellum.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amacrine Cells / metabolism*
  • Animals
  • Blotting, Western
  • Cyclic GMP / metabolism
  • Cyclic GMP-Dependent Protein Kinases / metabolism
  • Electroretinography / methods
  • Guanylate Cyclase / metabolism
  • Immunohistochemistry / methods
  • Indoles
  • Light
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout / physiology
  • Microfilament Proteins / metabolism
  • Nerve Tissue Proteins / deficiency
  • Nerve Tissue Proteins / metabolism*
  • Nitric Oxide / metabolism
  • Phosphoprotein Phosphatases / metabolism*
  • Qa-SNARE Proteins
  • RNA, Messenger / biosynthesis
  • Rats
  • Rats, Sprague-Dawley
  • Retina / cytology*
  • Retina / physiology
  • Retina / radiation effects
  • Retinal Ganglion Cells / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Signal Transduction / physiology*

Substances

  • G-substrate
  • Indoles
  • Membrane Proteins
  • Microfilament Proteins
  • Nerve Tissue Proteins
  • Qa-SNARE Proteins
  • RNA, Messenger
  • Nitric Oxide
  • DAPI
  • Cyclic GMP-Dependent Protein Kinases
  • Phosphoprotein Phosphatases
  • Guanylate Cyclase
  • Cyclic GMP