Splicing up synaptic strength

Neurexins, which are presynaptic cell adhesion molecules, have multiple alternatively spliced forms, but why this splicing is needed is unclear. Aoto et al. created mice that constitutively expressed a variant of neurexin 3 that includes alternatively spliced sequence 4 (NRX3^SS4+) and in which SS4 could be excised by Cre recombination. NRX3^SS4+ expression decreased postsynaptic AMPA receptor levels in neurons and impaired long-term potentiation in hippocampal slices. SS4 excision rescued these effects, suggesting that NRX3 alternative splicing may trans-synaptically regulate AMPA receptor trafficking and synaptic strength.