Fra-1 substitutes for c-Fos in AP-1-mediated signal transduction in retinal apoptosis

J Neurochem. 2002 Mar;80(6):1089-94. doi: 10.1046/j.0022-3042.2002.00807.x.

Abstract

Lack of the AP-1 member c-Fos protects photoreceptors against light-induced apoptosis, a model for retinal degeneration. In mice, light damage increases the activity of the transcription factor AP-1, while pharmacological suppression of AP-1 prevents apoptosis, suggesting the involvement of pro-apoptotic AP-1 target genes. Recently, however, it was shown that photoreceptors expressing Fra-1 in place of c-Fos (Fos (Fosl1/Fosl1) ) are apoptosis competent despite the lack of transactivation domains in Fra-1. Here, we show that morphological features of light-induced apoptosis were indistinguishable in Fos (Fosl1/Fosl1) and wild-type mice. Furthermore, light exposure comparably increased AP-1 activity in both genotypes. Opposite to wild-type mice, Fra-1, but not c-Fos, was detectable in AP-1 complexes of Fos (Fosl1/Fosl1) mice. Importantly, AP-1 responsiveness for glucocorticoid receptor-mediated inhibition was preserved in Fos (Fosl1/Fosl1) mice. Thus, Fra-1 takes over for c-Fos in pro- and anti-apoptotic signal transduction. As Fra-1 lacks transactivation domains, AP-1 may not induce, but rather suppress genes in retinal light damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Dexamethasone / pharmacology
  • Disease Models, Animal
  • Glucocorticoids / pharmacology
  • In Situ Nick-End Labeling
  • Light / adverse effects
  • Mice
  • Mice, Knockout
  • Proto-Oncogene Proteins c-fos / deficiency*
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism*
  • Receptors, Glucocorticoid / metabolism
  • Retina / drug effects
  • Retina / pathology
  • Retina / physiopathology*
  • Retina / radiation effects
  • Retinal Degeneration / pathology
  • Retinal Degeneration / physiopathology*
  • Retinal Degeneration / prevention & control
  • Signal Transduction*
  • Transcription Factor AP-1 / metabolism*
  • Transcriptional Activation

Substances

  • Glucocorticoids
  • Proto-Oncogene Proteins c-fos
  • Receptors, Glucocorticoid
  • Transcription Factor AP-1
  • fos-related antigen 1
  • Dexamethasone