Dendritic spine morphology and memory formation depend on postsynaptic Caskin proteins

Area of Science:

• Neuroscience
• Molecular Biology
• Cognitive Science

Background:

• Caskin1 and Caskin2 are neuronal scaffold proteins interacting with CASK.
• Previous studies suggested a minor role for Caskin1 in anxiety and pain perception.

Purpose of the Study:

• To investigate the role of Caskin1 and Caskin2 in cognitive functions.
• To elucidate the molecular mechanisms underlying Caskin proteins' function in the brain.

Main Methods:

• Generation of double knockout mice lacking Caskin1 and Caskin2.
• Behavioral tests for novelty recognition and spatial memory.
• Electrophysiological recordings (LTP, mEPSCs) in hippocampal slices and cultured neurons.
• Ultrastructural analysis of dendritic spines.
• Immunocytochemistry and immunoprecipitation to study protein interactions.

Main Results:

• Double knockout mice exhibited severe deficits in novelty recognition and spatial memory.
• Ultrastructural analysis showed reduced synaptic profiles and dendritic spine areas in CA1 hippocampal neurons.
• LTP induction was impaired in knockout mice, while mEPSCs were unaffected.
• Caskin1 overexpression increased mushroom-shaped dendritic spines in cultured neurons.
• Caskin proteins co-localized with Shank2, a postsynaptic density scaffold.
• AMPA receptor phosphorylation was altered by Caskin deficiency.

Conclusions:

• Caskin scaffold proteins play a significant postsynaptic role in regulating learning and memory.
• Caskins influence cognitive abilities by modulating dendritic spine morphology and AMPA receptor localization.
• The findings reveal a novel function of Caskin proteins in synaptic plasticity and neuronal function.