Journal article
Auxiliary Hyperkinetic β Subunit of K+Channels: Regulation of Firing Properties and K+ Currents in Drosophila Neurons
Journal of neurophysiology, Vol.81(5), pp.2472-2484
05/01/1999
DOI: 10.1152/jn.1999.81.5.2472
PMID: 10322082
Abstract
Auxiliary Hyperkinetic β subunit of K+channels: regulation of firing properties and K+ currents in Drosophila neurons. Molecular analysis and heterologous expression have shown that K+ channel β subunits regulate the properties of the pore-forming α subunits, although how they influence neuronal K+ currents and excitability remains to be explored. We studied cultured Drosophila “giant” neurons derived from mutants of the Hyperkinetic ( Hk) gene, which codes for a K+ channel β subunit. Whole cell patch-clamp recording revealed broadened action potentials and, more strikingly, persistent rhythmic spontaneous activities in a portion of mutant neurons. Voltage-clamp analysis demonstrated extensive alterations in the kinetics and voltage dependence of K+ current activation and inactivation, especially at subthreshold membrane potentials, suggesting a role in regulating the quiescent state of neurons that are capable of tonic firing. Altered sensitivity of Hk currents to classical K+ channel blockers (4-aminopyridine, α-dendrotoxin, and TEA) indicated that Hk mutations modify interactions between voltage-activated K+ channels and these pharmacological probes, apparently by changing both the intra- and extracellular regions of the channel pore. Correlation of voltage- and current-clamp data from the same cells indicated that Hkmutations affect not only the persistently active neurons, but also other neuronal categories. Shaker ( Sh) mutations, which alter K+ channel α subunits, increased neuronal excitability but did not cause the robust spontaneous activity characteristic of some Hk neurons. Significantly, Hk Sh double mutants were indistinguishable from Sh single mutants, implying that the rhythmic Hk firing pattern is conferred by intact Shα subunits in a distinct neuronal subpopulation. Our results suggest that alterations in β subunit regulation, rather than elimination or addition of α subunits, may cause striking modifications in the excitability state of neurons, which may be important for complex neuronal function and plasticity.
Details
- Title: Subtitle
- Auxiliary Hyperkinetic β Subunit of K+Channels: Regulation of Firing Properties and K+ Currents in Drosophila Neurons
- Creators
- Wei-Dong Yao - Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242Chun-Fang Wu - Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
- Resource Type
- Journal article
- Publication Details
- Journal of neurophysiology, Vol.81(5), pp.2472-2484
- DOI
- 10.1152/jn.1999.81.5.2472
- PMID
- 10322082
- ISSN
- 0022-3077
- eISSN
- 1522-1598
- Language
- English
- Date published
- 05/01/1999
- Academic Unit
- Iowa Neuroscience Institute; Biology
- Record Identifier
- 9984070948902771
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