Dense core vesicle release: controlling the where as well as the when

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Calcium/calmodulin-dependent Kinase II (CaMKII) is a calcium-regulated kinase involved in synaptic activity regulation.
• While its postsynaptic roles are established, its presynaptic functions, particularly in neurotransmitter release from synaptic vesicles (SVs), remain less clear.
• Dense-core vesicles (DCVs) release neuropeptides and neuromodulators, critical for brain function, but their regulation is poorly understood compared to SVs.

Purpose of the Study:

• To investigate the role of CaMKII in presynaptic cells beyond SV regulation.
• To explore CaMKII's function in the trafficking and release of dense-core vesicles (DCVs).
• To elucidate the mechanisms controlling DCV release, particularly preventing premature secretion.

Main Methods:

• The study by Hoover et al. (2014) investigated the role of active CaMKII in presynaptic cells.
• Experiments focused on the regulation of dense-core vesicle (DCV) release.
• The study examined the requirement for CaMKII kinase activity and calcium signaling from internal ER stores via ryanodine receptors.

Main Results:

• Active CaMKII is required cell-autonomously to prevent premature release of DCVs after budding from the Golgi.
• This CaMKII function necessitates its kinase activity and calcium signaling originating from internal ER stores.
• The findings reveal a novel presynaptic role for CaMKII in regulating DCV trafficking and release, distinct from its known roles in SVs.

Conclusions:

• CaMKII plays a critical role in preventing premature DCV release in presynaptic neurons.
• This function highlights a novel mechanism for regulating neuropeptide and neuromodulator secretion.
• The study provides a foundation for understanding DCV trafficking, docking, and release, crucial for brain function and mental health.