@article {46416, title = {Clathrin dependence of synaptic-vesicle formation at the Drosophila neuromuscular junction.}, journal = {Current Biology}, volume = {18}, year = {2008}, month = {2008 Mar 25}, pages = {401-9}, abstract = {

BACKGROUND: Among the most prominent molecular constituents of a recycling synaptic vesicle is the clathrin triskelion, composed of clathrin light chain (Clc) and clathrin heavy chain (Chc). Remarkably, it remains unknown whether clathrin is strictly necessary for the stimulus-dependent re-formation of a synaptic vesicle and, conversely, whether clathrin-independent vesicle endocytosis exists at the neuronal synapse.

RESULTS: We employ FlAsH-FALI-mediated protein photoinactivation to rapidly (3 min) and specifically disrupt Clc function at the Drosophila neuromuscular junction. We first demonstrate that Clc photoinactivation does not impair synaptic-vesicle fusion. We then provide electrophysiological and ultrastructural evidence that synaptic vesicles, once fused with the plasma membrane, cannot be re-formed after Clc photoinactivation. Finally, we demonstrate that stimulus-dependent membrane internalization occurs after Clc photoinactivation. However, newly internalized membrane fails to resolve into synaptic vesicles. Rather, newly internalized membrane forms large and extensive internal-membrane compartments that are never observed at a wild-type synapse.

CONCLUSIONS: We make three major conclusions. (1) FlAsH-FALI-mediated protein photoinactivation rapidly and specifically disrupts Clc function with no effect on synaptic-vesicle fusion. (2) Synaptic-vesicle re-formation does not occur after Clc photoinactivation. By extension, clathrin-independent "kiss-and-run" endocytosis does not sustain synaptic transmission during a stimulus train at this synapse. (3) Stimulus-dependent, clathrin-independent membrane internalization exists at this synapse, but it is unable to generate fusion-competent, small-diameter synaptic vesicles.

}, keywords = {Animals, Clathrin Light Chains, Drosophila, Electrophysiology, Endocytosis, Fluoresceins, Larva, Neuromuscular Junction, Organometallic Compounds, Synaptic Membranes, Synaptic Transmission, Synaptic Vesicles}, issn = {0960-9822}, doi = {10.1016/j.cub.2008.02.055}, author = {Heerssen, Heather and Fetter, Richard D and Davis, Graeme W} }