Naturally occurring (programmed) and radiation-induced apoptosis are associated with selective c-Jun expression in...

Area of Science:

• Neuroscience
• Molecular Biology
• Developmental Biology

Background:

• Transcription factors Fos and Jun regulate gene expression.
• Their roles in the developing brain, particularly during cell death, require further investigation.

Purpose of the Study:

• To investigate the expression patterns of Fos and Jun family members in the developing rat brain.
• To determine the specific role of c-Jun during programmed cell death and in response to ionizing radiation.

Main Methods:

• Immunohistochemistry to detect Fos and Jun proteins.
• In situ hybridization to detect c-jun mRNA.
• In situ labeling of nuclear DNA fragmentation to identify apoptotic cells.
• Cycloheximide treatment to assess protein synthesis dependence.

Main Results:

• Constitutive expression of c-Fos, Fos-related antigens, Jun B, and Jun D is higher in the developing brain than in adults.
• Selective and strong c-Jun expression is observed in apoptotic cells during programmed cell death.
• Ionizing radiation induces rapid c-jun mRNA and c-Jun protein expression in the developing rat brain.
• c-Jun expression is linked to endonuclease activation and DNA fragmentation in apoptotic cells.
• c-Jun expression following irradiation depends on de novo protein synthesis.

Conclusions:

• c-Jun is selectively expressed in apoptotic cells in the developing rat brain, both during normal programmed cell death and in response to ionizing radiation.
• These findings highlight a specific role for c-Jun in regulating cell death processes in the developing nervous system.