Communication between a motor neuron and a skeletal muscle fiber takes place at a synapse, the neuromuscular junction. Here both the neuron and muscle fiber are specialized in molecular and structural composition to form the "machinery" required for successful synaptic transmission. Our laboratory is interested in determining the factors involved in the formation and maintenance of the neuromuscular junction.
Our current aim is to determine the contribution of glial Schwann cells and extracellular matrix molecules to nerve terminal stability at the frog neuromuscular junction. The frog neuromuscular junction is a powerful system in which to study synapse stability since nerve terminals studied in the absence of target muscle can reveal nonmuscle stabilization interactions normally masked in the presence of muscle. Further, the stability of target-deprived nerve terminals can be manipulated to test for stabilization factors using either mature nerve terminals that are stabilized at synaptic sites or regenerated terminals that are unstable in the absence of muscle. Using in vivo repeated imaging of living frog nerve terminals, fluorescent probes, activity dependent dyes, and confocal microscopy, we are testing the contribution of the Schwann cells and matrix molecules in stability of nerve terminals. These experiments will provide needed insight into the nerve-target interactions governing the differentiation, growth, and maintenance of synapses.