Activity drives local CaMKII synthesis and subcellular localization via autophosphorylation-dependent pathways.

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Biology

Background:

• Neurons adjust protein levels locally for rapid response to stimulation.
• Calcium/calmodulin-dependent protein kinase II (CaMKII) is crucial for synaptic plasticity.
• Presynaptic CaMKII synthesis and its regulation remain poorly understood.

Purpose of the Study:

• Investigate the molecular mechanisms of activity-dependent presynaptic CaMKII synthesis.
• Determine the role of CaMKII mRNA localization and signaling pathways in this process.
• Examine how local synthesis and protein translocation contribute to distinct CaMKII pools.

Main Methods:

• Utilized the Drosophila larval neuromuscular junction (NMJ) model.
• Employed presynaptic-specific tagging of endogenous CaMKII.
• Analyzed CaMKII mRNA 3'UTR requirements and PI3K/Akt/mTor pathway activation.
• Conducted pulse-chase experiments with phosphomimetic CaMKII mutants.

Main Results:

• Spaced stimulation increases presynaptic CaMKII via local translation of existing mRNA.
• Activity-dependent synthesis requires the distal 3'UTR of CaMKII mRNA.
• CaMKII T287 autophosphorylation activates the PI3K/Akt/mTor pathway for synthesis.
• Newly synthesized CaMKII localizes differently from pre-existing CaMKII.

Conclusions:

• Neuronal activity drives local presynaptic CaMKII synthesis through specific mRNA elements and signaling pathways.
• Activity-dependent synthesis and translocation generate distinct CaMKII populations at synapses.
• These distinct CaMKII pools likely contribute to long-lasting synaptic plasticity.