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Regulation of neuronal excitability by interaction of fragile X mental retardation protein with slack potassium channels
- Source :
- The Journal of neuroscience : the official journal of the Society for Neuroscience. 32(44)
- Publication Year :
- 2012
-
Abstract
- Loss of the RNA-binding protein fragile X mental retardation protein (FMRP) represents the most common form of inherited intellectual disability. Studies with heterologous expression systems indicate that FMRP interacts directly with Slack Na+-activated K+channels (KNa), producing an enhancement of channel activity. We have now usedAplysiabag cell (BC) neurons, which regulate reproductive behaviors, to examine the effects of Slack and FMRP on excitability. FMRP and Slack immunoreactivity were colocalized at the periphery of isolated BC neurons, and the two proteins could be reciprocally coimmunoprecipitated. Intracellular injection of FMRP lacking its mRNA binding domain rapidly induced a biphasic outward current, with an early transient tetrodotoxin-sensitive component followed by a slowly activating sustained component. The properties of this current matched that of the native Slack potassium current, which was identified using an siRNA approach. Addition of FMRP to inside-out patches containing nativeAplysiaSlack channels increased channel opening and, in current-clamp recordings, produced narrowing of action potentials. Suppression of Slack expression did not alter the ability of BC neurons to undergo a characteristic prolonged discharge in response to synaptic stimulation, but prevented recovery from a prolonged inhibitory period that normally follows the discharge. Recovery from the inhibited period was also inhibited by the protein synthesis inhibitor anisomycin. Our studies indicate that, in BC neurons, Slack channels are required for prolonged changes in neuronal excitability that require new protein synthesis, and raise the possibility that channel–FMRP interactions may link changes in neuronal firing to changes in protein translation.
- Subjects :
- Patch-Clamp Techniques
Potassium Channels
Immunoprecipitation
Stimulation
CHO Cells
Biology
Inhibitory postsynaptic potential
Article
chemistry.chemical_compound
Fragile X Mental Retardation Protein
Cricetulus
Cricetinae
Aplysia
Animals
Patch clamp
Cloning, Molecular
RNA, Small Interfering
Anisomycin
Neurons
Protein Synthesis Inhibitors
General Neuroscience
Sodium
biology.organism_classification
Immunohistochemistry
Potassium channel
Cell biology
Electrophysiological Phenomena
chemistry
Synapses
RNA Interference
Neuroscience
Intracellular
Subjects
Details
- ISSN :
- 15292401
- Volume :
- 32
- Issue :
- 44
- Database :
- OpenAIRE
- Journal :
- The Journal of neuroscience : the official journal of the Society for Neuroscience
- Accession number :
- edsair.doi.dedup.....038db293ff66e73abfa8a17c75e3342d