ProSAP/Shank postsynaptic density proteins interact with insulin receptor tyrosine kinase substrate IRSp53

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Biology

Background:

• The postsynaptic density (PSD) is crucial for synaptic function, containing scaffolding proteins like ProSAP/Shank that link receptors to the cytoskeleton.
• ProSAP/Shank proteins interact with glutamate receptors and the actin cytoskeleton, playing a role in synaptic structure and plasticity.

Purpose of the Study:

• To identify proteins interacting with the ProSAP/Shank family.
• To investigate the functional role of IRSp53 in the postsynaptic density and neuronal morphology.

Main Methods:

• Yeast two-hybrid screening to identify ProSAP/Shank interacting partners.
• Co-immunoprecipitation in transfected cells and rat brain tissue to confirm in vivo interactions.
• Mutational analysis to define the interaction domains and sequences.
• Studies in neuronal cell lines to assess the effects of IRSp53 on actin dynamics.

Main Results:

• IRSp53 was identified as a binding partner for ProSAP/Shank proteins through its SH3 domain interacting with a novel proline-rich motif.
• The interaction between IRSp53 and ProSAP/Shank was confirmed in vivo in rat brain membranes.
• IRSp53, a substrate for the insulin receptor, acts downstream of Rho family GTPases.
• Cdc42Hs binding to IRSp53 promotes actin assembly, reorganization, and filopodia formation in neuronal cells.

Conclusions:

• IRSp53 can be recruited to the PSD via ProSAP/Shank, linking insulin receptor and Cdc42Hs signaling to synaptic structure.
• This interaction suggests a mechanism for morphological reorganization of dendritic spines and synapses.