KCNK

K2P (KCNK) potassium channels generate "leak" potassium currents that strongly influence cellular excitability and contribute to pain, somatosensation, anesthesia, and mood. Despite their physiological importance, K2Ps lack specific pharmacology. Addressing this issue has been complicated by the challenges that the leak nature of K2P currents poses for electrophysiology-based high-throughput screening strategies. Here, we present a yeast-based high-throughput screening assay that avoids this problem. Using a simple growth-based functional readout, we screened a library of 106,281 small molecules and identified two new inhibitors and three new activators of the mammalian K2P channel K2P2...

Two-pore domain K(+) (KCNK, K2P) channels underlie the "leak" (background) potassium conductance in many types of excitable cells. They oppose membrane depolarization and cell excitability. These channels have been reported to be modulated by several physical and chemical stimuli. The compound 2-aminoethoxydiphenyl borate (2-APB) was originally described as an inhibitor of IP3-induced Ca(2+) release but has been shown to act as either a blocker or an activator for several ion channels. Here, we report the effects of this compound on members of the TREK (TWIK related K(+) channels) subfamily of human KCNK channels...

The human endometrial epithelium is pivotal to menstrual cycle progression, implantation and early pregnancy. Endometrial function is directly regulated by local factors that include pH, oxygen tension and ion concentrations to generate an environment conducive to fertilization. A superfamily of potassium channels characterized by two-pore domains (K2P) and encoded by KCNK genes is implicated in the control of the cell resting membrane potential through the generation of leak currents and modulation by various physicochemical stimuli...

Development of the cerebral cortex depends partly on neural activity, but the identity of the ion channels that might contribute to the activity-dependent cortical development is unknown. KCNK channels are critical determinants of neuronal excitability in the mature cerebral cortex, and a member of the KCNK family, KCNK9, is responsible for a maternally transmitted mental retardation syndrome. Here, we have investigated the roles of KCNK family potassium channels in cortical development. Knockdown of KCNK2, 9, or 10 by RNAi using in utero electroporation impaired the migration of late-born cortical excitatory neurons destined to become Layer II/III neurons...

A cDNA encoding a potassium channel of the two-pore domain family (K(2P), KCNK) of leak channels was cloned from the marine sponge Amphimedon queenslandica. Phylogenetic analysis indicated that AquK(2P) cannot be placed into any of the established functional groups of mammalian K(2P) channels. We used the Xenopus oocyte expression system, a two-electrode voltage clamp and inside-out patch clamp electrophysiology to determine the physiological properties of AquK(2P). In whole cells, non-inactivating, voltage-independent, outwardly rectifying K(+) currents were generated by external application of micromolar concentrations of arachidonic acid (AA; EC(50) ∼30 μmol l(-1)), when applied in an alkaline solution (≥pH 8...

CONTEXT: Aldosterone production in the adrenal zona glomerulosa is mainly regulated by angiotensin II, [K(+)], and ACTH. Genetic deletion of subunits of K(+)-selective leak (KCNK) channels TWIK-related acid sensitive K(+)-1 and/or TWIK-related acid sensitive K(+)-3 in mice results in primary hyperaldosteronism, whereas mutations in the KCNJ5 (potassium inwardly rectifying channel, subfamily J, member 5) gene are implicated in primary hyperaldosteronism and, in certain cases, in autonomous glomerulosa cell proliferation in humans...

The major function of epithelial tissues is to maintain proper ion, solute, and water homeostasis. The tubule of the renal nephron has an amazingly simple structure, lined by epithelial cells, yet the segments (i.e., proximal tubule vs. collecting duct) of the nephron have unique transport functions. The functional differences are because epithelial cells are polarized and thus possess different patterns (distributions) of membrane transport proteins in the apical and basolateral membranes of the cell. K(+) channels play critical roles in normal physiology...

Two pore domain potassium (K2P) channels (KCNKx.x) cause K⁺ leak currents and are major contributors to resting membrane potential. Their roles in dorsal root ganglion (DRG) neurons normally, and in pathological pain models, are poorly understood. Therefore, we examined mRNA levels for 10 K2P channels in L4 and L5 rat DRGs normally, and 1 day and 4 days after unilateral cutaneous inflammation, induced by intradermal complete Freund's adjuvant (CFA) injections. Spontaneous foot lifting (SFL) duration (spontaneous pain behaviour) was measured in 1 day and 4 day rats <1h before DRG harvest...

Fast axonal conduction of action potentials in mammals relies on myelin insulation. Demyelination can cause slowed, blocked, desynchronized, or paradoxically excessive spiking that underlies the symptoms observed in demyelination diseases. The diversity and timing of such symptoms are poorly understood, often intermittent, and uncorrelated with disease progress. We modeled the effects of demyelination (and secondary remodeling) on intrinsic axonal excitability using Hodgkin-Huxley and reduced Morris-Lecar models...

Previous studies investigated the neural and molecular underpinnings of the tingle sensation evoked by sanshool and other natural or synthetic alkylamides. Currently, we sought to characterize the psychophysical properties associated with administration of these compounds. Like other chemesthetic stimuli, the synthetic tingle analog isobutylalkylamide (IBA) evoked a sensation that was temporally dynamic. Repeated IBA application at short (30 sec) interstimulus intervals (ISI) resulted in a tingle sensation that increased across trials...

We examined the possible protective effect of TASK-1 (TWIK-related acid-sensitive potassium channel-1, kcnk3) and -3 potassium channels during stroke. TASK-1 and TASK-3, members of the two pore domain (K2P or kcnk) potassium channel family, form hetero or homodimers and help set the resting membrane potential. We used male TASK-1 and TASK-3 knockout mice in a model of focal cerebral ischemia, permanent middle cerebral artery occlusion (pMCAO). Infarct volume was measured 48 h after pMCAO. The TASK-1 knockout brains had larger infarct volumes (P=0...

OBJECTIVES: Aldosterone production in the adrenal glomerulosa is mainly regulated by angiotensin II and K+. Adrenal glomerulosa cells are uniquely sensitive to extracellular K+. Genetic deletion of subunits of K+-selective leak-channels (KCNK), TASK1 and/or TASK3, in mice generates animals with hyperaldosteronism and histological changes in the adrenal cortex. Herein, we studied the expression of TASK1 in human adrenocortical cells, as well as its role in aldosterone production in H295R cells...

Sensing of sugar by specialized 'glucose-inhibited' cells helps organisms to counteract swings in their internal energy levels. Evidence from several cell types in both vertebrates and invertebrates suggests that this process involves sugar-induced stimulation of plasma membrane K(+) currents. However, the molecular composition and the mechanism of activation of the underlying channel(s) remain controversial. In mouse hypothalamic neurones and neurosecretory cells of the crab Cancer borealis, glucose stimulates K(+) currents displaying leak-like properties...

OBJECTIVE: Breastfeeding by human immunodeficiency virus (HIV)-positive mothers is an unavoidable practice in some very poor countries. It has been suggested that long-chain polyunsaturated fatty acids (LC-PUFAs) in breast milk, such as arachidonic acid, act as natural, protective ingredients against HIV transmission. The objective of this study was to identify the protective mechanism of LC-PUFAs in cells susceptible to HIV infection (e.g. human CD4+ T cells, HeLa cells). RESULTS: LC-PUFAs are bioactive molecules capable of activating the cellular protective machinery via modulation of endogenous background K+ or KCNK channels...

Constitutively active background or "leak" two-pore-domain potassium (K(+)) channels (Kcnk family), as defined by lack of voltage and time dependency are central to electrical excitability of cells by controlling resting membrane potential and membrane resistance. Inhibition of these channels by several neurotransmitters, e.g. glutamate, or acetylcholine, induces membrane depolarization and subsequent action potential firing as well as increases membrane resistance amplifying responses to synaptic inputs. In contrast, their opening contributes to hyperpolarization...

Two P loop domain potassium (K2P or KCNK) channels produce transmitter-modulated K+ currents that could influence brain development. We mapped by in situ hybridization the expression of the K2P gene family in the developing mouse brain. All the K2P genes had different expression patterns, and it is likely that many neuronal types change their K2P channel subunit composition during development. Fitting with a possible role in the control of cell division, three K2P genes (tandem of P domains in a weak inwardly-rectifying K+ channel-related K+ channel (TREK) -1, TREK-2 and weak inwardly-rectifying K+ channel-related acid-sensitive K+ channel (TASK) -2) had high expression in the embryonic subventricular and ventricular zones, and the tandem of P domains in a weak inwardly-rectifying K+ channel (TWIK) -1, TREK-1, TREK-2 and TASK-3 genes were significantly expressed in the external cerebellar granule cell layer...

Potassium (K+) channels are the most heterogeneous and widely distributed class of ion channels. K(+) channels are dynamic pore-forming transmembrane proteins known to play important roles in all cell types underlying both normal and pathophysiological functions. Essential for such diverse physiological processes as nerve impulse propagation, muscle contraction, cellular activation and the secretion of biologically active molecules, various K(+) channels are recognized as potential therapeutic targets in the treatment of multiple sclerosis, Alzheimer's disease, Parkinson's disease, epilepsy, stroke, brain tumors, brain/spinal cord ischemia, pain and schizophrenia, migraine, as well as cardiac arrhythmias, pulmonary hypertension, diabetes, cervical cancer, urological diseases and sepsis...

The mammalian family of two-pore domain K+ (K2P) channel proteins are encoded by 15 KCNK genes and subdivided into six subfamilies on the basis of sequence similarities: TWIK, TREK, TASK, TALK, THIK, and TRESK. K2P channels are expressed in cells throughout the body and have been implicated in diverse cellular functions including maintenance of the resting potential and regulation of excitability, sensory transduction, ion transport, and cell volume regulation, as well as metabolic regulation and apoptosis...

By analysis of whole cell membrane currents in Na(+)-absorbing H441 human airway epithelial cells, we have identified a K(+) conductance (G(K)) resistant to Ba(2+) but sensitive to bupivacaine or extracellular acidification. In polarized H441 monolayers, we have demonstrated that bupivacaine, lidocaine, and quinidine inhibit basolateral membrane K(+) current (I(Bl)) whereas Ba(2+) has only a weak inhibitory effect. I(Bl) was also inhibited by basolateral acidification, and, although subsequent addition of bupivacaine caused a further fall in I(Bl), acidification had no effect after bupivacaine, demonstrating that cells grown under these conditions express at least two different bupivacaine-sensitive K(+) channels, only one of which is acid sensitive...

Potassium channels share a common selectivity filter that determines the conduction characteristics of the pore. Diversity in K+ channels is given by how they are gated open. TASK-2, TALK-1, and TALK-2 are two-pore region (2P) KCNK K+ channels gated open by extracellular alkalinization. We have explored the mechanism for this alkalinization-dependent gating using molecular simulation and site-directed mutagenesis followed by functional assay. We show that the side chain of a single arginine residue (R224) near the pore senses pH in TASK-2 with an unusual pKa of 8...