PUBLICATION
Coordinated Expression of Two Types of Low-Threshold K+ Channels Establishes Unique Single Spiking of Mauthner Cells among Segmentally Homologous Neurons in the Zebrafish Hindbrain.
- Authors
- Watanabe, T., Shimazaki, T., Oda, Y.
- ID
- ZDB-PUB-171101-5
- Date
- 2017
- Source
- eNeuro 4(5): (Journal)
- Registered Authors
- Oda, Yoichi
- Keywords
- Kv1.1, Kv7.4, KvĪ²2, Mauthner cell, phasic firing, simulation
- MeSH Terms
-
- Cations, Monovalent/metabolism
- Computer Simulation
- Xenopus laevis
- Patch-Clamp Techniques
- Potassium Channels/metabolism*
- Potassium/metabolism
- Animals, Genetically Modified
- Action Potentials/drug effects
- Action Potentials/physiology*
- Models, Neurological
- Neurons/cytology*
- Neurons/drug effects
- Neurons/metabolism*
- Animals
- Oocytes
- Zebrafish
- In Situ Hybridization
- Cochlea/cytology
- Cochlea/metabolism
- Rhombencephalon/cytology*
- Rhombencephalon/drug effects
- Rhombencephalon/metabolism*
- Larva
- Sodium/metabolism
- Potassium Channel Blockers/pharmacology
- PubMed
- 29085904 Full text @ eNeuro
Citation
Watanabe, T., Shimazaki, T., Oda, Y. (2017) Coordinated Expression of Two Types of Low-Threshold K+ Channels Establishes Unique Single Spiking of Mauthner Cells among Segmentally Homologous Neurons in the Zebrafish Hindbrain.. eNeuro. 4(5).
Abstract
Expression of different ion channels permits homologously-generated neurons to acquire different types of excitability and thus code various kinds of input information. Mauthner (M) series neurons in the teleost hindbrain consist of M cells and their morphological homologs, which are repeated in adjacent segments and share auditory inputs. When excited, M cells generate a single spike at the onset of abrupt stimuli, while their homologs encode input intensity with firing frequency. Our previous study in zebrafish showed that immature M cells burst phasically at 2 d postfertilization (dpf) and acquire single spiking at 4 dpf by specific expression of auxiliary Kvβ2 subunits in M cells in association with common expression of Kv1.1 channels in the M series. Here, we further reveal the ionic mechanisms underlying this functional differentiation. Pharmacological blocking of Kv7/KCNQ in addition to Kv1 altered mature M cells to fire tonically, similar to the homologs. In contrast, blocking either channel alone caused M cells to burst phasically. M cells at 2 dpf fired tonically after blocking Kv7. In situ hybridization revealed specific Kv7.4/KCNQ4 expression in M cells at 2 dpf. Kv7.4 and Kv1.1 channels expressed in Xenopus oocytes exhibited low-threshold outward currents with slow and fast rise times, while coexpression of Kvβ2 accelerated and increased Kv1.1 currents, respectively. Computational models, modified from a mouse cochlear neuron model, demonstrated that Kv7.4 channels suppress repetitive firing to produce spike-frequency adaptation, while Kvβ2-associated Kv1.1 channels increase firing threshold and decrease the onset latency of spiking. Altogether, coordinated expression of these low-threshold K+ channels with Kvβ2 functionally differentiates M cells among homologous neurons.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping