Ras and Rap Signal Bidirectional Synaptic Plasticity via Distinct Subcellular Microdomains

Area of Science:

• Cell Biology
• Neuroscience
• Molecular Biology

Background:

• Understanding signal diversity and specificity in cellular communication is crucial.
• Ras-family small GTPases play key roles in cellular signaling pathways.
• The precise localization of signaling molecules dictates their function.

Purpose of the Study:

• To develop a method for targeted delivery of homologous Ras-family small GTPases (Ras, Rap2, Rap1) to specific subcellular microdomains.
• To investigate the role of microdomain-specific signaling in controlling synaptic plasticity.
• To elucidate the mechanisms underlying signal diversity and specificity of Ras and Rap proteins.

Main Methods:

• Development of a targeted delivery system for expressing Ras-family GTPases in specific subcellular locations (endoplasmic reticulum, lipid rafts, bulk membrane, lysosomes, Golgi complex) in rodent hippocampal CA1 neurons.
• Utilized multicolor fluorescence protein tagging for visualization.
• Employed high-resolution dual-quintuple simultaneous patch-clamp recordings for functional analysis.

Main Results:

• Ras signaling mediates long-term potentiation through endoplasmic reticulum PI3K and lipid raft ERK.
• Rap2 signaling is involved in depotentiation via bulk membrane JNK.
• Rap1 signaling contributes to long-term depression through lysosome p38MAPK.

Conclusions:

• Established an effective method for subcellular microdomain-specific targeted delivery of signaling proteins.
• Demonstrated that subcellular microdomain-specific signaling is the mechanism by which homologous Ras and Rap proteins achieve signal diversity and specificity.
• Unveiled the distinct roles of Ras, Rap2, and Rap1 in controlling different forms of synaptic plasticity through their localization-specific signaling pathways.