Rabconnectin3alpha promotes stable activity of the H+ pump on synaptic vesicles in hair cells

Einhorn, Z., Trapani, J.G., Liu, Q., and Nicolson, T.
The Journal of neuroscience : the official journal of the Society for Neuroscience   32(32): 11144-11156 (Journal)
Registered Authors
Einhorn, Zev, Liu, Qianyong, Nicolson, Teresa, Trapani, Josef
MeSH Terms
  • Acoustic Stimulation/adverse effects
  • Action Potentials/genetics
  • Adaptor Proteins, Signal Transducing/genetics
  • Adaptor Proteins, Signal Transducing/metabolism*
  • Analysis of Variance
  • Animals
  • Animals, Genetically Modified
  • Enzyme Inhibitors/pharmacology
  • Escape Reaction/drug effects
  • Escape Reaction/physiology
  • Green Fluorescent Proteins/genetics
  • Green Fluorescent Proteins/metabolism
  • Hair Cells, Auditory/cytology*
  • Larva
  • Lateral Line System/metabolism
  • Macrolides/pharmacology
  • Membrane Transport Proteins/genetics
  • Membrane Transport Proteins/metabolism
  • Microscopy, Confocal
  • Molecular Biology
  • Mutation/genetics
  • Physical Stimulation
  • Proton Pumps/metabolism*
  • RNA, Messenger/metabolism
  • Sensation Disorders/genetics
  • Synaptic Vesicles/drug effects
  • Synaptic Vesicles/metabolism*
  • Vacuolar Proton-Translocating ATPases/metabolism
  • Video Recording
  • Vision Disorders/genetics
  • Zebrafish
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism
22875945 Full text @ J. Neurosci.

Acidification of synaptic vesicles relies on the vacuolar-type ATPase (V-ATPase) and provides the electrochemical driving force for neurotransmitter exchange. The regulatory mechanisms that ensure assembly of the V-ATPase holoenzyme on synaptic vesicles are unknown. Rabconnectin3α (Rbc3α) is a potential candidate for regulation of V-ATPase activity because of its association with synaptic vesicles and its requirement for acidification of intracellular compartments. Here, we provide the first evidence for a role of Rbc3α in synaptic vesicle acidification and neurotransmission. In this study, we characterized mutant alleles of rbc3α isolated from a large-scale screen for zebrafish with auditory/vestibular defects. We show that Rbc3α is localized to basal regions of hair cells in which synaptic vesicles are present. To determine whether Rbc3α regulates V-ATPase activity, we examined the acidification of synaptic vesicles and localization of the V-ATPase in hair cells. In contrast to wild-type hair cells, we observed that synaptic vesicles had elevated pH, and a cytosolic subunit of the V-ATPase was no longer enriched in synaptic regions of mutant hair cells. As a consequence of defective acidification of synaptic vesicles, afferent neurons in rbc3α mutants had reduced firing rates and reduced accuracy of phase-locked action potentials in response to mechanical stimulation of hair cells. Collectively, our data suggest that Rbc3α modulates synaptic transmission in hair cells by promoting V-ATPase activity in synaptic vesicles.

Genes / Markers
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Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Engineered Foreign Genes
Errata and Notes