Activation of c-Jun and ATF-2 in primate motor cranial nerve nuclei is not associated with apoptosis following axotomy

Exp Neurol. 2005 Jul;194(1):57-65. doi: 10.1016/j.expneurol.2005.01.024.

Abstract

Nerve transection induces complex changes in gene regulation and expression that can have profound phenotypic effects on the fate of axotomized neurons. The transcription factors c-Jun and ATF-2 (activating transcription factor-2) are components of a regulatory network that mediates survival, regeneration, and apoptosis following axotomy in rodents. The activation and function of c-Jun and ATF-2 after nerve injury have not been examined in primates. Using a novel model of cranial nerve injury in baboons, we have examined the temporality of c-Jun activation (phosphorylation) in cranial nerve (CN) III and CN VI neurons and ATF-2 activation in CN VI neurons at 2, 4, and 9 days post-injury by immunohistochemistry. Furthermore, we have addressed whether the activation of these factors is associated with apoptosis by the TUNEL assay. We report that activated c-Jun is present in CN III and CN VI neurons ipsilateral to axotomy at 2, 4, and 9 days post-injury, but not in neurons contralateral to injury. Additionally, CN VI neurons ipsilateral to injury at 4 and 9 days contain activated ATF-2. Furthermore, no evidence of TUNEL reactivity was observed in either nucleus, regardless of laterality, at any of the examined time points. These findings suggest that activation of both c-Jun and ATF-2 does not mediate apoptosis in axotomized primate CN III and CN VI neurons at time points up to 9 days. This report serves as a basic inquiry into the neuronal response to cranial nerve injury in primates.

MeSH terms

  • Abducens Nerve / cytology
  • Abducens Nerve / metabolism
  • Abducens Nerve Injury / metabolism
  • Abducens Nerve Injury / physiopathology
  • Activating Transcription Factor 2
  • Animals
  • Apoptosis / physiology*
  • Axotomy
  • Brain Stem / metabolism
  • Brain Stem / pathology
  • Cranial Nerve Injuries / metabolism*
  • Cranial Nerve Injuries / pathology
  • Cranial Nerve Injuries / physiopathology
  • Cyclic AMP Response Element-Binding Protein / metabolism*
  • Disease Models, Animal
  • Disease Progression
  • Functional Laterality / physiology
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Male
  • Motor Neurons / metabolism*
  • Motor Neurons / pathology
  • Oculomotor Nerve / cytology
  • Oculomotor Nerve / metabolism
  • Oculomotor Nerve Injuries
  • Papio anubis
  • Phosphorylation
  • Proto-Oncogene Proteins c-jun / metabolism*
  • Retrograde Degeneration / metabolism*
  • Retrograde Degeneration / pathology
  • Retrograde Degeneration / physiopathology
  • Time Factors
  • Transcription Factors / metabolism*
  • Transcriptional Activation / physiology

Substances

  • Activating Transcription Factor 2
  • Cyclic AMP Response Element-Binding Protein
  • Proto-Oncogene Proteins c-jun
  • Transcription Factors