DREAM (downstream regulatory element antagonist modulator) contributes to synaptic depression and contextual fear...

Area of Science:

• Neuroscience
• Molecular Biology
• Calcium Signaling

Background:

• Downstream regulatory element antagonist modulator (DREAM) is a Ca2+-binding protein involved in gene expression and cellular excitability.
• DREAM is highly expressed in the central nervous system, particularly the hippocampus and cortex.
• The specific functions of DREAM in hippocampal synaptic transmission and plasticity remain largely unexplored.

Purpose of the Study:

• To investigate the role of DREAM in synaptic transmission, long-term plasticity, and fear memory in the hippocampal CA1 region.
• To elucidate the molecular mechanisms underlying DREAM's function in the hippocampus.
• To assess the impact of a Ca2+-insensitive DREAM mutant on neuronal function and behavior.

Main Methods:

• Utilized transgenic mice overexpressing a Ca2+-insensitive DREAM mutant (TgDREAM).
• Employed electrophysiology to measure NMDA and AMPA receptor-mediated currents.
• Conducted biochemical assays (e.g., interaction studies with PSD-95), immunostaining, and behavioral tests (fear memory, sensory responses).

Main Results:

• TgDREAM mice exhibited decreased NMDA receptor currents but normal AMPA receptor currents.
• Long-term depression (LTD) was impaired in TgDREAM mice, while long-term potentiation (LTP) remained unaffected.
• DREAM was found to interact with PSD-95, potentially inhibiting NMDA receptor function.
• Contextual fear memory was significantly impaired in TgDREAM mice, whereas sensory responses were normal.

Conclusions:

• DREAM plays a novel role in the postsynaptic modulation of NMDA receptors.
• DREAM is crucial for regulating synaptic plasticity, specifically LTD, in the hippocampus.
• DREAM significantly contributes to the formation and consolidation of behavioral fear memory.