Anti-KCTD12 (aa 125-175) polyclonal antibody

Following the discovery of GABA(B) receptors by Norman Bowery and colleagues, cloning and biochemical efforts revealed that GABA(IB) receptors assemble multi-subunit complexes composed of principal and auxiliary subunits. The principal receptor subunits GABA(B1a), GABA(B1b) and GABA(B2) form two heterodimeric GABA(B(1a,2)) and GABA(B(1b,2)) receptors that can associate with tetramers of auxiliary KCTD (K+ channel tetramerization domain) subunits. Experiments with subunit knock-out mice revealed that GABA(B(1b,2)) receptors activate slow inhibitory postsynaptic currents (sIPSCs) while GABA(B(1a,2)) receptors function as heteroreceptors and inhibit glutamate release. Both GABA(B(1a,2)) and GABA(B(1b,2)) receptors can serve as autoreceptors and inhibit GABA release. Auxiliary KCTD subunits regulate the duration of sIPSCs and scaffold effector channels at the receptor. GABA(B) receptors are well known to contribute to thalamic spindle oscillations. Spindles are generated through alternating burst-firing in reciprocally connected glutamatergic thalamocortical relay (TCR) and GABAergic thalamic reticular nucleus (TRN) neurons. The available data implicate postsynaptic GABA(B) receptors in TCR cells in the regulation of spindle frequency. We now used electrical or optogenetic activation of thalamic spindles and pharmacological experiments in acute slices of knock-out mice to study the impact of GABA(B(1a,2)) and GABA(B(1b,2)) receptors on spindle oscillations. We found that selectively GABA(B(1a,2)) heteroreceptors at TCR to TRN cell synapses regulate oscillation strength, while GABA(B(1b,2) )receptors control oscillation frequency. The auxiliary subunit KCTD16 influences both oscillation strength and frequency, supporting that KCTD16 regulates network activity through GABA(B(1a,2)) and GABA(B(1b,2)) receptors. This article is part of the "Special Issue Dedicated to Norman G. Bowery". (C) 2017 Elsevier Ltd. All rights reserved.

The molecular composition and functional diversity of native GABA(B) receptors (GABA(B)R) are still poorly understood, thus hindering development of selective GABA(B)R ligands. Potassium channel tetramerization domain-containing protein (KCTD) 12 is a GABA(B)R auxiliary subunit and mouse KCTD12 can alter GABA(B)R function. In this study, we sought to characterize the effects of human KCTD12 on GABA(B)R kinetics and pharmacology, using an automated electrophysiological assay. Seizure susceptibility and ethanol consumption were also investigated in a KCTD12 knockout mouse model. Human KCTD12 co-expression altered the kinetics of GABA(B)R-mediated GIRK channels, speeding rates of both activation and desensitization. Analysis of concentration-response curves showed that KCTD12 coexpression did not alter effects of the agonists GABA or baclofen on GABA(B)R. KCTD12 coexpression enhanced the potentiating effects of the positive allosteric modulator CGP7930, and its effects on GABA(B)R activation and desensitization. The function of KCTD12 invivo was examined, using the KCTD12 knockout mouse model. The knockout mice were more resistant to a pentylenetetrazole proconvulsant challenge suggesting reduced seizure susceptibility. In the two bottle preference test, KCTD12 knockout mice demonstrated a reduced consumption at high ethanol concentrations. In summary, human KCTD12 accelerated the kinetics of GABA(B)R invitro, in a manner possibly sensitive to allosteric pharmacological modulation. This study also provides novel invivo evidence that the interaction between KCTD12 and GABA(B)R is of physiological significance, and may be a mechanism to more selectively modulate GABA(B)R.