Glutamatergic neurons induce expression of functional glutamatergic synapses in primary myotubes

Background: The functioning of the nervous system depends upon the specificity of its synaptic contacts. The mechanismstriggering the expression of the appropriate receptors on postsynaptic membrane and the role of the presynaptic partner inthe differentiation of postsynaptic structures are little known.Methods and Findings: To address these questions we cocultured murine primary muscle cells with several glutamatergic neurons, either cortical, cerebellar or hippocampal. Immunofluorescence and electrophysiology analyses revealed that functional excitatory synaptic contacts were formed between glutamatergic neurons and muscle cells. Moreover,immunoprecipitation and immunofluorescence experiments showed that typical anchoring proteins of central excitatorysynapses coimmunoprecipitate and colocalize with rapsyn, the acetylcholine receptor anchoring protein at the neuromuscular junction.Conclusions: These results support an important role of the presynaptic partner in the induction and differentiation of thepostsynaptic structures.