GABAB receptors are the G-protein coupled receptors for the main inhibitory neurotransmitter in the brain, GABA. GABAB receptors were shown to associate with homo-oligomers of auxiliary KCTD8, KCTD12, KCTD12b, and KCTD16 subunits (named after their T1 K(+)-channel tetramerization domain) that regulate G-protein signaling of the receptor. Here we provide evidence that GABAB receptors also associate with hetero-oligomers of KCTD subunits. Coimmunoprecipitation experiments indicate that two-thirds of the KCTD16 proteins in the hippocampus of adult mice associate with KCTD12. We show that the KCTD proteins hetero-oligomerize through self-interacting T1 and H1 homology domains. Bioluminescence resonance energy transfer measurements in live cells reveal that KCTD12/KCTD16 hetero-oligomers associate with both the receptor and the G-protein. Electrophysiological experiments demonstrate that KCTD12/KCTD16 hetero-oligomers impart unique kinetic properties on G-protein-activated Kir3 currents. During prolonged receptor activation (one min) KCTD12/KCTD16 hetero-oligomers produce moderately desensitizing fast deactivating K(+) currents, whereas KCTD12 and KCTD16 homo-oligomers produce strongly desensitizing fast deactivating currents and nondesensitizing slowly deactivating currents, respectively. During short activation (2 s) KCTD12/KCTD16 hetero-oligomers produce nondesensitizing slowly deactivating currents. Electrophysiological recordings from hippocampal neurons of KCTD knock-out mice are consistent with these findings and indicate that KCTD12/KCTD16 hetero-oligomers increase the duration of slow IPSCs. In summary, our data demonstrate that simultaneous assembly of distinct KCTDs at the receptor increases the molecular and functional repertoire of native GABAB receptors and modulates physiologically induced K(+) current responses in the hippocampus. SIGNIFICANCE STATEMENT: The KCTD proteins 8, 12, and 16 are auxiliary subunits of GABAB receptors that differentially regulate G-protein signaling of the receptor. The KCTD proteins are generally assumed to function as homo-oligomers. Here we show that the KCTD proteins also assemble hetero-oligomers in all possible dual combinations. Experiments in live cells demonstrate that KCTD hetero-oligomers form at least tetramers and that these tetramers directly interact with the receptor and the G-protein. KCTD12/KCTD16 hetero-oligomers impart unique kinetic properties to GABAB receptor-induced Kir3 currents in heterologous cells. KCTD12/KCTD16 hetero-oligomers are abundant in the hippocampus, where they prolong the duration of slow IPSCs in pyramidal cells. Our data therefore support that KCTD hetero-oligomers modulate physiologically induced K(+) current responses in the brain.
- MeSH
- CHO buňky MeSH
- Cricetulus MeSH
- draslíkové kanály genetika metabolismus MeSH
- elektrofyziologické jevy genetika MeSH
- excitační postsynaptické potenciály genetika MeSH
- kinetika MeSH
- křečci praví MeSH
- metoda terčíkového zámku MeSH
- mozek - chemie genetika MeSH
- myši knockoutované MeSH
- myši MeSH
- receptory GABA-B genetika metabolismus MeSH
- receptory KIR metabolismus MeSH
- receptory spřažené s G-proteiny metabolismus MeSH
- zvířata MeSH
- Check Tag
- křečci praví MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Production of superoxide anions in the incubation medium of hippocampal slices can induce long-term potentiation (LTP). Other reactive oxygen species (ROS) such as hydrogen peroxide are able to modulate LTP and are likely to be involved in aging mechanisms. The present study explored whether intracerebro-ventricular (ICV) injection of oxidant or antioxidant molecules could affect LTP in vivo. With this aim in mind, field excitatory post-synaptic potentials (fEPSPs) elicited by stimulation of the perforant pathway were recorded in the dentate gyrus of the hippocampal formation in urethane-anesthetized rats. N-acetyl-L-cysteine, hydrogen peroxide (H2O2) or hypoxanthine/xanthine-oxidase solution (a superoxide producing system) were administrated by ICV injection. The control was represented by a group injected with saline ICV. Ten minutes after the injection, LTP was induced in the granule cells of the dentate gyrus by high frequency stimulation of the perforant pathway. Neither the H(2)O(2) injection or the N-acetyl-L-cysteine injection caused any variation in the fEPSP at the 10-min post-injection time point, whereas the superoxide generating system caused a significant increase in the fEPSP. Moreover, at 60 min after tetanic stimulation, all treatments attenuated LTP compared with the control group. These results show that ICV administration of oxidant or antioxidant molecules can modulate LTP in vivo in the dentate gyrus. Particularly, a superoxide producing system can induce potentiation of the synaptic response. Interestingly, ICV injection of oxidants or antioxidants prevented a full expression of LTP compared to the saline injection.
- MeSH
- acetylcystein aplikace a dávkování metabolismus MeSH
- analýza rozptylu MeSH
- anestetika intravenózní farmakologie MeSH
- dlouhodobá potenciace fyziologie účinky léků MeSH
- elektrická stimulace MeSH
- ethyl-karbamát farmakologie MeSH
- excitační postsynaptické potenciály genetika účinky záření MeSH
- gyrus dentatus fyziologie účinky léků MeSH
- hypoxanthin aplikace a dávkování MeSH
- injekce intraventrikulární MeSH
- krysa rodu rattus MeSH
- oxidace-redukce účinky léků MeSH
- oxidancia aplikace a dávkování metabolismus MeSH
- perforující nervová dráha fyziologie MeSH
- peroxid vodíku aplikace a dávkování metabolismus MeSH
- potkani Sprague-Dawley MeSH
- scavengery volných radikálů aplikace a dávkování metabolismus MeSH
- xanthinoxidasa aplikace a dávkování MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
The miniature excitatory postsynaptic currents (MEPCs) of the muscle cells of the earthworm Lumbricus terrestris were recorded by glass microelectrodes. In a single synaptic zone, three types of MEPC were recorded: a fast singleexponential type that decayed with ? =0.9 ms, a slow single-exponential with ? = 9.2 ms and a two-exponential MEPC with ? = 1.3 and 8.5 ms, respectively. The muscle cells of earthworms contain populations of yet-unidentified ionic channels that might be different from the common nicotinic and muscarinic groups of acetylcholine receptors, since these MEPCs are not sensitive to d-tubocurarine, atropine, benzohexonium or proserine. Alternatively, besides ACh receptors, the membrane may contain receptors for another yet-unidentified excitatory transmitter.
- MeSH
- acetylcholin metabolismus MeSH
- bránice cytologie metabolismus MeSH
- excitační postsynaptické potenciály genetika MeSH
- hibernace MeSH
- křečci praví MeSH
- membránové potenciály fyziologie účinky léků MeSH
- motorické neurony fyziologie MeSH
- nedepolarizující myorelaxancia farmakologie MeSH
- zvířata MeSH
- Check Tag
- křečci praví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
