Polo-like kinases in the nervous system

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Polo-like kinases (Plks) are crucial for cell cycle regulation.
• Their functions in postmitotic neurons, like those in the brain, remain largely unexplored.
• Neuronal Plk2 and Plk3 are modulated by synaptic activity at both mRNA and protein levels.

Purpose of the Study:

• To investigate the role of Plk2 and Plk3 in neuronal function.
• To understand how Plks affect synaptic structure and molecular composition.
• To explore the potential involvement of Plks in activity-dependent synaptic plasticity.

Main Methods:

• Investigated Plk2 and Plk3 interactions with SPAR (spine-associated Rap GTPase-activating protein) in COS cells.
• Utilized induction of Plk2 in hippocampal neurons.
• Assessed changes in SPAR protein, PSD-95 levels, dendritic spine morphology, and synapse number.

Main Results:

• Plk2 and Plk3 interact with SPAR, promoting its degradation via the ubiquitin-proteasome system.
• Induction of Plk2 in hippocampal neurons led to SPAR elimination, PSD-95 depletion, and loss of mature dendritic spines and synapses.
• These findings highlight Plks' role in modifying synaptic molecular composition and morphology.

Conclusions:

• Neuronal Plks are implicated as mediators of activity-dependent changes in synaptic structure and function.
• Induced Plks may contribute to synaptic scaling, a homeostatic mechanism for dampening synaptic strength after high activity.
• Specific synapse targeting of Plks is possible through interactions with primed substrates, suggesting localized regulatory roles.