CD44: a novel synaptic cell adhesion molecule regulating structural and functional plasticity of dendritic spines

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Synaptic cell adhesion molecules are vital for neuronal communication and plasticity.
• The interaction between neurons and the extracellular matrix (ECM), particularly through receptors like CD44, is not fully understood in synaptic function.

Purpose of the Study:

• To investigate the role of CD44, a hyaluronan receptor, in modulating synaptic plasticity and neuronal structure.
• To elucidate the molecular mechanisms by which CD44 influences dendritic spine morphology and function.

Main Methods:

• High-resolution ultrastructural analysis of synapses in the adult brain.
• Electrophysiological recordings of primary hippocampal neurons with reduced CD44 expression.
• Assessment of synaptic protein levels (e.g., Bassoon, PSD-95) and actin cytoskeleton regulator activity (Rho GTPases).

Main Results:

• CD44 is localized at mature synapses.
• Reduced CD44 expression impaired excitatory synaptic transmission and altered dendritic spine shape (elongation, thinning).
• CD44 deficiency decreased presynaptic Bassoon puncta and postsynaptic PSD-95, indicating fewer functional synapses and abrogated spine enlargement upon stimulation.
• CD44 modulates Rho GTPase activity, affecting actin cytoskeleton regulation.

Conclusions:

• CD44 plays a significant role in regulating synaptic plasticity.
• CD44 is essential for maintaining dendritic spine structure and function.
• CD44 acts as a novel molecular regulator of synaptic plasticity through modulation of the actin cytoskeleton.