Hippocampal synaptic transmission and plasticity are preserved in myosin Va mutant mice

Recent studies have identified myosin Va as an organelle motor that may hav e important functions in neurons. Abundantly expressed at the hippocampal p ostsynaptic density, it interacts with protein complexes involved in synapt ic plasticity. It is also located in presynaptic terminals and may function to recruit vesicles in the reserve pool to the active zone. Dilute-lethal mice are spontaneous myosin Va mutants and have severe neurological symptom s. We studied hippocampal physiology at CA3-CA1 excitatory synapses in dilu te-lethal mutant mice to test the hypothesis that myosin Va plays a role in pre- or postsynaptic elements of synaptic transmission. In all assays perf ormed, the mutant synapses appeared to be functioning normally, both pre- a nd postsynaptically. These data suggest that myosin Va is not essential for the synaptic release machinery, postsynaptic receptor composition, or plas ticity at this synapse, but does not exclude significant roles for myosin V a in other cell types nor potential compensation by other myosin V isoforms .