Synaptic Ribbons Require Ribeye for Electron Density, Proper Synaptic Localization, and Recruitment of Calcium Channels.
Synaptic ribbons are structures made largely of the protein Ribeye that hold synaptic vesicles near release sites in non-spiking cells in some sensory systems. Here, we introduce frameshift mutations in the two zebrafish genes encoding for Ribeye and thus remove Ribeye protein from neuromast hair cells. Despite Ribeye depletion, vesicles collect around ribbon-like structures that lack electron density, which we term "ghost ribbons." Ghost ribbons are smaller in size but possess a similar number of smaller vesicles and are poorly localized to synapses and calcium channels. These hair cells exhibit enhanced exocytosis, as measured by capacitance, and recordings from afferent neurons post-synaptic to hair cells show no significant difference in spike rates. Our results suggest that Ribeye makes up most of the synaptic ribbon density in neuromast hair cells and is necessary for proper localization of calcium channels and synaptic ribbons.
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8066, USA.
Caixia
C
Lv
The Whitney Laboratory for Marine Bioscience and Department of Biology, University of Florida, St. Augustine, FL 32080, USA.
William J
WJ
Stewart
The Whitney Laboratory for Marine Bioscience and Department of Biology, University of Florida, St. Augustine, FL 32080, USA.
Otar
O
Akanyeti
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8066, USA.
Courtney
C
Frederick
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8066, USA.
Jie
J
Zhu
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8066, USA; Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, CT 06520-8066, USA; Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520-8066, USA.
Joseph
J
Santos-Sacchi
Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA 02114, USA.
Lavinia
L
Sheets
The Whitney Laboratory for Marine Bioscience and Department of Biology, University of Florida, St. Augustine, FL 32080, USA.
James C
JC
Liao
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8066, USA; Department of Opthalmology and Visual Sciences, Yale University School of Medicine, New Haven, CT 06520-8066, USA. Electronic address: david.zenisek@yale.edu.
David
D
Zenisek
D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D025802:Electric Capacitance; D004583:Electrons; D005089:Exocytosis; D005136:Eye Proteins / Q000378:metabolism*; D006198:Hair Cells, Auditory / Q000378:metabolism; D006720:Homozygote; D015640:Ion Channel Gating; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009475:Neurons, Afferent / Q000378:metabolism; D018408:Patch-Clamp Techniques; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000648:ultrastructure; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism*
D015220:Calcium Channels; D005136:Eye Proteins; D009419:Nerve Tissue Proteins; D029961:Zebrafish Proteins; C577847:ctbp2a protein, zebrafish; C000623202:ctbp2l protein, zebrafish
exocytosis; hair cell; hearing; retina; synaptic ribbon; vestibular system