cJun and CREB2 in the postsynaptic neuron contribute to persistent long-term facilitation at a behaviorally relevant...

Area of Science:

• Neuroscience
• Molecular Biology
• Synaptic Plasticity

Background:

• Basic region leucine zipper (bZIP) transcription factors regulate gene expression vital for neuronal functions.
• CREB1 and CREB2 in sensory neurons are known to be essential for long-term synaptic plasticity in Aplysia.
• The role of bZIP factors in postsynaptic motor neurons during long-term plasticity remains largely unexplored.

Purpose of the Study:

• To investigate whether stimulus-induced changes in bZIP transcription factors in postsynaptic motor neurons contribute to persistent long-term facilitation (P-LTF).
• To examine the specific roles of CREB1, CREB2, and cJun in motor neuron L7 in P-LTF.

Main Methods:

• Overexpression of CREB1, CREB2, and cJun variants in the postsynaptic motor neuron L7 of Aplysia in cell culture.
• Induction of P-LTF using two consecutive days of 5-HT applications, contrasted with transient LTF from one day.
• Analysis of changes in mRNA expression, basal synapse strength, and P-LTF following bZIP factor manipulation.

Main Results:

• Significant increases in cJun and CREB2 mRNA expression in L7 motor neurons were observed during P-LTF.
• Co-overexpression of cJun and CREB2 in L7 motor neurons led to persistent increases in basal synapse strength.
• Overexpression of cJun or CREB2 in L7 could substitute for the second 5-HT application to induce P-LTF, while reducing cJun activity blocked P-LTF.

Conclusions:

• Both expression and activation of distinct bZIP factors in presynaptic and postsynaptic neurons are critical for persistent synaptic changes.
• cJun and CREB2 in the postsynaptic motor neuron play a significant role in mediating stimulus-dependent long-term synaptic plasticity.
• These findings highlight the complex molecular mechanisms underlying learning and memory at the synaptic level.