Wnt-5a is a synaptogenic factor with neuroprotective properties against Aβ toxicity

Background: We have recently found that Wnt-5a regulates the synaptic structure and function in hippocampal neurons. This ligand is expressed in the hippocampus, stimulates dendritic spine morphogenesis and increases glutamatergic neurotransmission. Moreover, we have also shown that Wnt-5a induces the clustering of PSD-95. Objective: To explore the role of Wnt-5a in the formation of synaptic contacts. Methods: Primary rat hippocampal neurons were exposed to a formylated hexapeptide (Foxy-5) derived from the sequence of Wnt-5a to study synapse formation and function. Results: In short-term experiments, Wnt-5a only induced the clustering of PSD-95 but had no effect on the density of presynaptic puncta, while in long-term experiments, it induced both pre- and postsynaptic protein clustering and the number of synaptic contacts, in agreement with electrophysiological studies. In long-term experiments, Foxy-5 increased miniature excitatory postsynaptic current amplitude and frequency. Conclusion: Our findings indicate that Wnt-5a induces synapse formation in hippocampal neurons. In addition, we discuss recent findings indicating a neuroprotective action of Wnt-5a against Aβ neurotoxicity.