Neurotransmitter receptor dynamics studied in vivo by reversible photo-unbinding of fluorescent ligands.
We show that fluorescently tagged ligands with high affinity for their targets can be reversibly unbound by focused laser excitation. By sequential unbinding and relabeling with different colors of alpha-bungarotoxin, we selectively labeled adjacent pools of acetylcholine receptors (AChRs) at neuromuscular junctions of adult mice. Timelapse imaging in vivo revealed that synaptic AChRs completely intermingle over approximately 4 days and many extrasynaptic AChRs are incorporated into the synapse each day. In mice that lacked alpha-dystrobrevin, a component of the dystrophin-glycoprotein complex, rates of AChR turnover, and intermingling were increased approximately 4- to 5-fold. These results demonstrate remarkable molecular dynamism underlying macroscopic stability of the postsynaptic membrane, and establish alpha-dystrobrevin as a key control point for regulation of mobility and turnover.
Akaaboune
Mohammed
M
Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
Grady
R Mark
RM
Turney
Steve
S
Sanes
Joshua R
JR
Lichtman
Jeff W
JW
D000818:Animals; D001667:Binding, Competitive / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000172:deficiency / Q000235:genetics; D049029:Dystrophin-Associated Proteins; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism*; D008024:Ligands; D008027:Light; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics; D051379:Mice; D008856:Microscopy, Fluorescence; D009469:Neuromuscular Junction / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism / Q000502:physiology; D017981:Receptors, Neurotransmitter / Q000378:metabolism* / Q000502:physiology
D003598:Cytoskeletal Proteins; D049029:Dystrophin-Associated Proteins; D005456:Fluorescent Dyes; D008024:Ligands; D008565:Membrane Proteins; D011950:Receptors, Cholinergic; D017981:Receptors, Neurotransmitter; C098885:dystrobrevin