scn1bb, a Zebrafish Ortholog of SCN1B Expressed in Excitable and Nonexcitable Cells, Affects Motor Neuron Axon Morphology and Touch Sensitivity

Fein, A.J., Wright, M.A., Slat, E.A., Ribera, A.B., and Isom, L.L.
The Journal of neuroscience : the official journal of the Society for Neuroscience   28(47): 12510-12522 (Journal)
Registered Authors
Ribera, Angie, Wright, Melissa
Na+ channel, auxiliary subunit, cell adhesion, electrophysiology, zebrafish, touch sensitivity
MeSH Terms
  • Analysis of Variance
  • Animals
  • Animals, Genetically Modified
  • Antibodies, Monoclonal/pharmacology
  • Axons/drug effects
  • Axons/physiology*
  • Body Patterning/genetics
  • Body Patterning/physiology
  • Central Nervous System/cytology
  • Central Nervous System/metabolism
  • Embryo, Nonmammalian
  • Epithelial Cells/metabolism
  • Gene Expression Regulation, Developmental/drug effects
  • Gene Expression Regulation, Developmental/genetics
  • Green Fluorescent Proteins/biosynthesis
  • Green Fluorescent Proteins/genetics
  • Kidney/cytology
  • Kidney/embryology
  • Kidney/metabolism
  • Motor Neurons/classification
  • Motor Neurons/cytology*
  • Motor Neurons/drug effects
  • Motor Neurons/physiology*
  • Neuroglia/physiology*
  • Sequence Alignment/methods
  • Sodium Channels/immunology
  • Sodium Channels/metabolism*
  • Spinal Cord/cytology
  • Touch/physiology*
  • Tubulin/metabolism
  • Voltage-Gated Sodium Channel beta-1 Subunit
  • Zebrafish
  • Zebrafish Proteins/immunology
  • Zebrafish Proteins/metabolism*
19020043 Full text @ J. Neurosci.
Voltage-gated Na(+) channels initiate and propagate action potentials in excitable cells. Mammalian Na(+) channels are composed of one pore-forming alpha-subunit and two beta-subunits. SCN1B encodes the Na(+) channel beta1-subunit that modulates channel gating and voltage dependence, regulates channel cell surface expression, and functions as a cell adhesion molecule (CAM). We recently identified scn1ba, a zebrafish ortholog of SCN1B. Here we report that zebrafish express a second beta1-like paralog, scn1bb. In contrast to the restricted expression of scn1ba mRNA in excitable cells, we detected scn1bb transcripts and protein in several ectodermal derivatives including neurons, glia, the lateral line, peripheral sensory structures, and tissues derived from other germ layers such as the pronephros. As expected for beta1-subunits, elimination of Scn1bb protein in vivo by morpholino knock-down reduced Na(+) current amplitudes in Rohon-Beard neurons of zebrafish embryos, consistent with effects observed in heterologous systems. Further, after Scn1bb knock-down, zebrafish embryos displayed defects in Rohon-Beard mediated touch sensitivity, demonstrating the significance of Scn1bb modulation of Na(+) current to organismal behavior. In addition to effects associated with Na(+) current modulation, Scn1bb knockdown produced phenotypes consistent with CAM functions. In particular, morpholino knock-down led to abnormal development of ventrally projecting spinal neuron axons, defasciculation of the olfactory nerve, and increased hair cell number in the inner ear. We propose that, in addition to modulation of electrical excitability, Scn1bb plays critical developmental roles by functioning as a CAM in the zebrafish embryonic nervous system.
Genes / Markers
Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Engineered Foreign Genes
Errata and Notes