Innervation regulates synaptic ribbons in lateral line mechanosensory hair cells.
Failure to form proper synapses in mechanosensory hair cells, the sensory cells responsible for hearing and balance, leads to deafness and balance disorders. Ribbons are electron-dense structures that tether synaptic vesicles to the presynaptic zone of mechanosensory hair cells where they are juxtaposed with the post-synaptic endings of afferent fibers. They are initially formed throughout the cytoplasm, and, as cells mature, ribbons translocate to the basolateral membrane of hair cells to form functional synapses. We have examined the effect of post-synaptic elements on ribbon formation and maintenance in the zebrafish lateral line system by observing mutants that lack hair cell innervation, wild-type larvae whose nerves have been transected and ribbons in regenerating hair cells. Our results demonstrate that innervation is not required for initial ribbon formation but suggest that it is crucial for regulating the number, size and localization of ribbons in maturing hair cells, and for ribbon maintenance at the mature synapse.
Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA Department of Biological Structure, University of Washington, Seattle, WA 98195, USA asuli@byu.edu.
Arminda
0000-0003-2690-8407
A
Suli
V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA INSERM-Unit 1051, Université Montpellier, France.
Remy
R
Pujol
V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA.
Dale E
DE
Cunningham
Department of Biological Structure, University of Washington, Seattle, WA 98195, USA V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA.
Dale W
DW
Hailey
Department of Biological Structure, University of Washington, Seattle, WA 98195, USA Institut du Cerveau et de la Moelle Épinère 47, Boulevard de l'Hôpital, 75013 Paris, France.
Andrew
A
Prendergast
V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA.
Edwin W
EW
Rubel
Department of Biological Structure, University of Washington, Seattle, WA 98195, USA.
David W
DW
Raible
D000818:Animals; D006199:Hair Cells, Auditory, Inner / Q000378:metabolism* / Q000648:ultrastructure; D053403:Lateral Line System / Q000294:innervation* / Q000378:metabolism* / Q000648:ultrastructure; D040542:Mechanotransduction, Cellular; D008566:Membranes / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000378:metabolism / Q000648:ultrastructure; D015027:Zebrafish
Innervation; Mechanosensory hair cells; Neurogenin 1; Ribbon synapse; Sputnik; Zebrafish