DGKι regulates presynaptic release during mGluR-dependent LTD.

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Biology

Background:

• Diacylglycerol (DAG) acts as a crucial lipid second messenger in cellular signaling.
• Diacylglycerol kinases (DGKs) terminate DAG signaling by converting DAG to phosphatidic acid (PA).
• The neuronal synapse is a key location for DAG production and function, but DGK targeting mechanisms remain unclear.

Purpose of the Study:

• To investigate the synaptic localization mechanisms of DGKι.
• To elucidate the presynaptic role of DGKι in neurotransmitter release and synaptic plasticity.
• To understand the regulation of DGKι function in metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD).

Main Methods:

• Co-immunoprecipitation assays to study protein interactions.
• Confocal microscopy for subcellular localization studies.
• Electrophysiological recordings in DGKι-deficient mice to assess synaptic function.
• Pharmacological inhibition of protein kinase C.

Main Results:

• Postsynaptic density (PSD)-95 family proteins interact with and facilitate the synaptic localization of DGKι.
• DGKι functions presynaptically, unlike its postsynaptic relative DGKζ.
• DGKι deficiency in mice results in increased presynaptic release probability and impaired mGluR-LTD at neonatal stages.
• Inhibition of protein kinase C rescues presynaptic release probability and mGluR-LTD in DGKι-deficient synapses.

Conclusions:

• DGKι synaptic localization is mediated by PSD-95 family proteins.
• DGKι plays a critical role in regulating presynaptic DAG signaling and neurotransmitter release during mGluR-LTD.
• These findings reveal a novel presynaptic function for DGKι in synaptic plasticity.