Epigenetic mechanisms in stress and adaptation

Area of Science:

• Neuroscience
• Epigenetics
• Endocrinology

Background:

• Epigenetic mechanisms control gene expression but their role in neuro-immuno-endocrine communication is unclear.
• Environmental factors without DNA sequence changes profoundly influence physiology and behavior via epigenetics.

Purpose of the Study:

• To review epigenetic modifications induced by stressors.
• To examine how these epigenetic variations affect cellular biological activity.
• To explore the role of epigenetic mechanisms in neuro-immuno-endocrine communication.

Main Methods:

• Focus on epigenetic modifications induced by physical and psychological stressors.
• Identification of a hippocampal signaling pathway (MEK-ERK1/2, MSK1, Elk-1) affecting histone H3 and gene expression.
• Investigation of glucocorticoid (GC) hormone and receptor (GR) involvement in stress response pathways.

Main Results:

• Stressors like forced swimming and fear conditioning activate the ERK1/2/MSK1-Elk-1 pathway in the hippocampus.
• This pathway leads to histone H3 phospho-acetylation and altered gene expression, including immediate early genes (e.g., c-Fos).
• Glucocorticoid hormones enhance this pathway, amplifying epigenetic and gene expression changes.

Conclusions:

• Epigenetic modifications are critical mediators of environmental influences on physiology and behavior.
• The identified signaling pathway plays a key role in adaptive responses to stress and learning.
• Synergistic interactions between stress pathways and glucocorticoids impact gene expression and potentially immune function.