A critical role of the amyloid precursor protein (APP) in Alzheimer's disease (AD) pathogenesis has been well established. However, the physiological function of APP remains elusive and much debated. We reported previously that the APP family of proteins is essential in mediating the developing neuromuscular synapse. In the current study, we created a conditional allele of APP and deleted APP in presynaptic motor neuron or postsynaptic muscle. Crossing these alleles onto the APP-like protein 2-null background reveals that, unexpectedly, inactivating APP in either compartment results in neuromuscular synapse defects similar to the germline deletion and that postsynaptic APP is obligatory for presynaptic targeting of the high-affinity choline transporter and synaptic transmission. Using a HEK293 and primary hippocampus mixed-culture assay, we report that expression of APP in HEK293 cells potently promotes synaptogenesis in contacting axons. This activity is dependent on neuronal APP and requires both the extracellular and intracellular domains; the latter forms a complex with Mint1 and Cask and is replaceable by the corresponding SynCAM (synaptic cell adhesion molecule) sequences. These in vitro and in vivo studies identify APP as a novel synaptic adhesion molecule. We postulate that transsynaptic APP interaction modulates its synaptic function and that perturbed APP synaptic adhesion activity may contribute to synaptic dysfunction and AD pathogenesis.
We have not found any resources mentioned in this publication.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to SciCrunch, however this is not currently a free service.