Two-Pore Domain Potassium Channels as Drug Targets: Anesthesia and Beyond.

Two-pore domain potassium (K2P) channels stabilize the resting membrane potential of both excitable and nonexcitable cells and, as such, are important regulators of cell activity. There are many conditions where pharmacological regulation of K2P channel activity would be of therapeutic benefit, including, but not limited to, atrial fibrillation, respiratory depression, pulmonary hypertension, neuropathic pain, migraine, depression, and some forms of cancer. Up until now, few if any selective pharmacological regulators of K2P channels have been available. However, recent publications of solved structures with small-molecule activators and inhibitors bound to TREK-1, TREK-2, and TASK-1 K2P channels have given insight into the pharmacophore requirements for compound binding to these sites. Together with the increasing availability of a number of novel, active, small-molecule compounds from K2P channel screening programs, these advances have opened up the possibility of rational activator and inhibitor design to selectively target K2P channels.

Pharmacological Approaches to Studying Potassium Channels.

In this review, we consider the pharmacology of potassium channels from the perspective of these channels as therapeutic targets. Firstly, we describe the three main families of potassium channels in humans and disease states where they are implicated. Secondly, we describe the existing therapeutic agents which act on potassium channels and outline why these channels represent an under-exploited therapeutic target with potential for future drug development. Thirdly, we consider the evidence desired in order to embark on a drug discovery programme targeting a particular potassium channel. We have chosen two "case studies": activators of the two-pore domain potassium (K2P) channel TREK-2 (K2P10.1), for the treatment of pain and inhibitors of the voltage-gated potassium channel KV1.3, for use in autoimmune diseases such as multiple sclerosis. We describe the evidence base to suggest why these are viable therapeutic targets. Finally, we detail the main technical approaches available to characterise the pharmacology of potassium channels and identify novel regulatory compounds. We draw particular attention to the Comprehensive in vitro Proarrhythmia Assay initiative (CiPA, https://cipaproject.org ) project for cardiac safety, as an example of what might be both desirable and possible in the future, for ion channel regulator discovery projects.

Opportunistic screening for atrial fibrillation by clinical pharmacists in UK general practice during the influenza vaccination season: A cross-sectional feasibility study.

BACKGROUND: Growing prevalence of atrial fibrillation (AF) in the ageing population and its associated life-changing health and resource implications have led to a need to improve its early detection. Primary care is an ideal place to screen for AF; however, this is limited by shortages in general practitioner (GP) resources. Recent increases in the number of clinical pharmacists within primary care makes them ideally placed to conduct AF screening. This study aimed to determine the feasibility of GP practice-based clinical pharmacists to screen the over-65s for AF, using digital technology and pulse palpation during the influenza vaccination season. METHODS AND FINDINGS: Screening was conducted over two influenza vaccination seasons, 2017-2018 and 2018-2019, in four GP practices in Kent, United Kingdom. Pharmacists were trained by a cardiologist to pulse palpate, record, and interpret a single-lead ECG (SLECG). Eligible persons aged ≥65 years (y) attending an influenza vaccination clinic were offered a free heart rhythm check. Six hundred four participants were screened (median age 73 y, 42.7% male). Total prevalence of AF was 4.3%. All participants with AF qualified for anticoagulation and were more likely to be male (57.7%); be older; have an increased body mass index (BMI); and have a CHA2DS2-VASc (Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes, previous Stroke, Vascular disease, Age 65-74 years, Sex category) score ≥ 3. The sensitivity and specificity of clinical pharmacists diagnosing AF using pulse palpation was 76.9% (95% confidence interval [CI] 56.4-91.0) and 92.2% (95% CI 89.7-94.3), respectively. This rose to 88.5% (95% CI 69.9-97.6) and 97.2% (95% CI 95.5-98.4) with an SLECG. At follow-up, four participants (0.7%) were diagnosed with new AF and three (0.5%) were initiated on anticoagulation. Screening with SLECG also helped identify new non-AF cardiovascular diagnoses, such as left ventricular hypertrophy, in 28 participants (4.6%). The screening strategy was cost-effective in 71.8% and 64.3% of the estimates for SLECG or pulse palpation, respectively. Feedback from participants (422/604) was generally positive. Key limitations of the study were that the intervention did not reach individuals who did not attend the practice for an influenza vaccination and there was a limited representation of UK ethnic minority groups in the study cohort. CONCLUSIONS: This study demonstrates that AF screening performed by GP practice-based pharmacists was feasible, economically viable, and positively endorsed by participants. Furthermore, diagnosis of AF by the clinical pharmacist using an SLECG was more sensitive and more specific than the use of pulse palpation alone. Future research should explore the key barriers preventing the adoption of national screening programmes.

Characterization and regulation of wild-type and mutant TASK-1 two pore domain potassium channels indicated in pulmonary arterial hypertension.

KEY POINTS: The TASK-1 channel gene (KCNK3) has been identified as a possible disease-causing gene in heritable pulmonary arterial hypertension (PAH). In the present study, we show that novel mutated TASK-1 channels, seen in PAH patients, have a substantially reduced current compared to wild-type TASK-1 channels. These mutated TASK-1 channels are located at the plasma membrane to the same degree as wild-type TASK-1 channels. ONO-RS-082 and alkaline pH 8.4 both activate TASK-1 channels but do not recover current through mutant TASK-1 channels. We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK-1 channels but does not recover current through mutant TASK-1 channels. ABSTRACT: Pulmonary arterial hypertension (PAH) affects ∼15-50 people per million. KCNK3, the gene that encodes the two pore domain potassium channel TASK-1 (K2P3.1), has been identified as a possible disease-causing gene in heritable PAH. Recently, two new mutations have been identified in KCNK3 in PAH patients: G106R and L214R. The present study aimed to characterize the functional properties and regulation of wild-type (WT) and mutated TASK-1 channels and determine how these might contribute to PAH and its treatment. Currents through WT and mutated human TASK-1 channels transiently expressed in tsA201 cells were measured using whole-cell patch clamp electrophysiology. Localization of fluorescence-tagged channels was visualized using confocal microscopy and quantified with in-cell and on-cell westerns. G106R or L214R mutated channels were located at the plasma membrane to the same degree as WT channels; however, their current was markedly reduced compared to WT TASK-1 channels. Functional current through these mutated channels could not be restored using activators of WT TASK-1 channels (pH 8.4, ONO-RS-082). The guanylate cyclase activator, riociguat, enhanced current through WT TASK-1 channels; however, similar to the other activators investigated, riociguat did not have any effect on current through mutated TASK-1 channels. Thus, novel mutations in TASK-1 seen in PAH substantially alter the functional properties of these channels. Current through these channels could not be restored by activators of TASK-1 channels. Riociguat enhancement of current through TASK-1 channels could contribute to its therapeutic benefit in the treatment of PAH.

Pranlukast is a novel small molecule activator of the two-pore domain potassium channel TREK2.

TREK2 (KCNK10, K2P10.1) is a two-pore domain potassium (K2P) channel and a potential target for the treatment of pain. Like the majority of the K2P superfamily, there is currently a lack of useful pharmacological tools to study TREK2. Here we present a strategy for identifying novel TREK2 activators. A cell-based thallium flux assay was developed and used to screen a library of drug-like molecules, from which we identified the CysLT1 antagonist Pranlukast as a novel activator of TREK2. This compound was selective for TREK2 versus TREK1 and showed no activity at TRAAK. Pranlukast was also screened against other members of the K2P superfamily. Several close analogues of Pranlukast and other CysLT1 antagonists were also tested for their ability to activate K2P channels. Consistent with previous work, structure activity relationships showed that subtle structural changes to these analogues completely attenuated the activation of TREK2, whereas for TREK1, analogues moved from activators to inhibitors. Pranlukast's activity was also confirmed using whole-cell patch clamp electrophysiology. Studies using mutant forms of TREK2 suggest Pranlukast does not bind in the K2P modulator pocket or the BL-1249 binding site. Pranlukast therefore represents a novel tool by which to study the mechanism of TREK2 activation.

Terbinafine is a novel and selective activator of the two-pore domain potassium channel TASK3.

Two-pore domain potassium channels (K2Ps) are characterized by their four transmembrane domain and two-pore topology. They carry background (or leak) potassium current in a variety of cell types. Despite a number of important roles there is currently a lack of pharmacological tools with which to further probe K2P function. We have developed a cell-based thallium flux assay, using baculovirus delivered TASK3 (TWIK-related acid-sensitive K+ channel 3, KCNK9, K2P9.1) with the aim of identifying novel, selective TASK3 activators. After screening a library of 1000 compounds, including drug-like and FDA approved molecules, we identified Terbinafine as an activator of TASK3. In a thallium flux assay a pEC50 of 6.2 ( ±0.12) was observed. When Terbinafine was screened against TASK2, TREK2, THIK1, TWIK1 and TRESK no activation was observed in thallium flux assays. Several analogues of Terbinafine were also purchased and structure activity relationships examined. To confirm Terbinafine's activation of TASK3 whole cell patch clamp electrophysiology was carried out and clear potentiation observed in both the wild type channel and the pathophysiological, Birk-Barel syndrome associated, G236R TASK3 mutant. No activity at TASK1 was observed in electrophysiology studies. In conclusion, we have identified the first selective activator of the two-pore domain potassium channel TASK3.

TASK-1 (KCNK3) channels in the lung: from cell biology to clinical implications.

TWIK-related acid-sensitive potassium channel 1 (TASK-1 encoded by KCNK3) belongs to the family of two-pore domain potassium channels. This gene subfamily is constitutively active at physiological resting membrane potentials in excitable cells, including smooth muscle cells, and has been particularly linked to the human pulmonary circulation. TASK-1 channels are sensitive to a wide array of physiological and pharmacological mediators that affect their activity such as unsaturated fatty acids, extracellular pH, hypoxia, anaesthetics and intracellular signalling pathways. Recent studies show that modulation of TASK-1 channels, either directly or indirectly by targeting their regulatory mechanisms, has the potential to control pulmonary arterial tone in humans. Furthermore, mutations in KCNK3 have been identified as a rare cause of both familial and idiopathic pulmonary arterial hypertension. This review summarises our current state of knowledge of the functional role of TASK-1 channels in the pulmonary circulation in health and disease, with special emphasis on current advancements in the field.

Enhancement of TWIK-related acid-sensitive potassium channel 3 (TASK3) two-pore domain potassium channel activity by tumor necrosis factor α.

TASK3 two-pore domain potassium (K2P) channels are responsible for native leak K channels in many cell types which regulate cell resting membrane potential and excitability. In addition, TASK3 channels contribute to the regulation of cellular potassium homeostasis. Because TASK3 channels are important for cell viability, having putative roles in both neuronal apoptosis and oncogenesis, we sought to determine their behavior under inflammatory conditions by investigating the effect of TNFα on TASK3 channel current. TASK3 channels were expressed in tsA-201 cells, and the current through them was measured using whole cell voltage clamp recordings. We show that THP-1 human myeloid leukemia monocytes, co-cultured with hTASK3-transfected tsA-201 cells, can be activated by the specific Toll-like receptor 7/8 activator, R848, to release TNFα that subsequently enhances hTASK3 current. Both hTASK3 and mTASK3 channel activity is increased by incubation with recombinant TNFα (10 ng/ml for 2-15 h), but other K2P channels (hTASK1, hTASK2, hTREK1, and hTRESK) are unaffected. This enhancement by TNFα is not due to alterations in levels of channel expression at the membrane but rather to an alteration in channel gating. The enhancement by TNFα can be blocked by extracellular acidification but persists for mutated TASK3 (H98A) channels that are no longer acid-sensitive even in an acidic extracellular environment. TNFα action on TASK3 channels is mediated through the intracellular C terminus of the channel. Furthermore, it occurs through the ASK1 pathway and is JNK- and p38-dependent. In combination, TNFα activation and TASK3 channel activity can promote cellular apoptosis.

Two-pore domain potassium channels: potential therapeutic targets for the treatment of pain.

Recent evidence points to a pivotal contribution of a variety of different potassium channels, including two-pore domain potassium (K2P) channels, in chronic pain processing. Expression of several different K2P channel subunits has been detected in nociceptive dorsal root ganglion neurons and trigeminal ganglion neurons, in particular, TREK1, TREK2, TRESK, TRAAK, TASK3 and TWIK1 channels. Of these, the strongest body of evidence from functional studies highlights the importance of TREK1, TRESK and, recently, TREK2 channels. For example, TREK1 knockout mice are more sensitive than wild-type mice to a number of painful stimuli but less sensitive to morphine-induced analgesia. TRESK knockdown mice show behavioural evidence of increased pain and increased sensitivity to painful pressure. Importantly, familial migraine with aura is associated with a dominant-negative mutation in human TRESK channels. Thus, the functional up-regulation of K2P channel activity may be a useful strategy in the development of new therapies for the treatment of pain. Whilst there are few currently available compounds that selectively and directly enhance the activity of TRESK and TREK2 channels, recent advances have been made in terms of identifying compounds that activate TREK1 channels and in understanding how they might act on the channel. Large-scale bio-informatic approaches and the further development of databases of putative ligands, channel structures and putative ligand binding sites on these structures may form the basis for future experimental strategies to detect novel molecules acting to enhance K2P channel activity that would be useful in the treatment of pain.

Recovery of current through mutated TASK3 potassium channels underlying Birk Barel syndrome.

TASK3 (TWIK-related acid-sensitive K(+) channel 3) potassium channels are members of the two-pore-domain potassium channel family. They are responsible for background leak potassium currents found in many cell types. TASK3 channels are genetically imprinted, and a mutation in TASK3 (G236R) is responsible for Birk Barel mental retardation dysmorphism syndrome, a maternally transmitted developmental disorder. This syndrome may arise from a neuronal migration defect during development caused by dysfunctional TASK3 channels. Through the use of whole-cell electrophysiologic recordings, we have found that, although G236R mutated TASK3 channels give rise to a functional current, this current is significantly smaller in an outward direction when compared with wild-type (WT) TASK3 channels. In contrast to WT TASK3 channels, the current is inwardly rectifying. Furthermore, the current through mutated channels is differentially sensitive to a number of regulators, such as extracellular acidification, extracellular zinc, and activation of Gαq-coupled muscarinic (M3) receptors, compared with WT TASK3 channels. The reduced outward current through mutated TASK3_G236R channels can be overcome, at least in part, by both a gain-of-function additional mutation of TASK3 channels (A237T) or by application of the nonsteroidal anti-inflammatory drug flufenamic acid (FFA; 2-{[3-(trifluoromethyl)phenyl]amino}benzoic acid). FFA produces a significantly greater enhancement of current through mutated channels than through WT TASK3 channels. We propose that pharmacologic enhancement of mutated TASK3 channel current during development may, therefore, provide a potentially useful therapeutic strategy in the treatment of Birk Barel syndrome.

Influence of the N terminus on the biophysical properties and pharmacology of TREK1 potassium channels.

TWIK-related K(+) 1 (TREK1) potassium channels are members of the two-pore domain potassium channel family and contribute to background potassium conductances in many cell types, where their activity can be regulated by a variety of physiologic and pharmacologic mediators. Fenamates such as FFA (flufenamic acid; 2-{[3-(trifluoromethyl)phenyl]amino}benzoic acid), MFA [mefenamic acid; 2-(2,3-dimethylphenyl)aminobenzoic acid], NFA [niflumic acid; 2-{[3-(trifluoromethyl)phenyl]amino}nicotinic acid], and diclofenac [2-(2-(2,6-dichlorophenylamino)phenyl)acetic acid] and the related experimental drug BL-1249 [(5,6,7,8-tetrahydro-naphthalen-1-yl)-[2-(1H-tetrazol-5-yl)-phenyl]-amine] enhance the activity of TREK1 currents, and we show that BL-1249 is the most potent of these compounds. Alternative translation initiation produces a shorter, N terminus truncated form of TREK1 with a much reduced open probability and a proposed increased permeability to sodium compared with the longer form. We show that both forms of TREK1 can be activated by fenamates and that a number of mutations that affect TREK1 channel gating occlude the action of fenamates but only in the longer form of TREK1. Furthermore, fenamates produce a marked enhancement of current through the shorter, truncated form of TREK1 and reveal a K(+)-selective channel, like the long form. These results provide insight into the mechanism of TREK1 channel activation by fenamates, and, given the role of TREK1 channels in pain, they suggest a novel analgesic mechanism for these compounds.

The Concise Guide to PHARMACOLOGY 2023/24: Nuclear hormone receptors.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and nearly 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16179. Nuclear hormone receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

The Concise Guide to PHARMACOLOGY 2023/24: Enzymes.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and about 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16176. In addition to this overview, in which are identified 'Other protein targets' which fall outside of the subsequent categorisation, there are six areas of focus: G protein-coupled receptors, ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

The Concise Guide to PHARMACOLOGY 2023/24: Transporters.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16182. Transporters are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, ion channels, nuclear hormone receptors, catalytic receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

The Concise Guide to PHARMACOLOGY 2023/24: Catalytic receptors.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and nearly 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16180. Catalytic receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, ion channels, nuclear hormone receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

The Concise Guide to PHARMACOLOGY 2023/24: Ion channels.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16178. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

The Concise Guide to PHARMACOLOGY 2023/24: Introduction and Other Protein Targets.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and about 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16176. In addition to this overview, in which are identified 'Other protein targets' which fall outside of the subsequent categorisation, there are six areas of focus: G protein-coupled receptors, ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

The Concise Guide to PHARMACOLOGY 2023/24: G protein-coupled receptors.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and about 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.16177. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

A KCNB1 gain of function variant causes developmental delay and speech apraxia but not seizures.

Objective: Numerous pathogenic variants in KCNB1, which encodes the voltage-gated potassium channel, KV2.1, are linked to developmental and epileptic encephalopathies and associated with loss-of-function, -regulation, and -expression of the channel. Here we describe a novel de novo variant (P17T) occurring in the KV2.1 channel that is associated with a gain-of-function (GoF), with altered steady-state inactivation and reduced sensitivity to the selective toxin, guanxitoxin-1E and is clinically associated with neurodevelopmental disorders, without seizures. Methods: The autosomal dominant variant was identified using whole exome sequencing (WES). The functional effects of the KCNB1 variant on the encoded KV2.1 channel were investigated using whole-cell patch-clamp recordings. Results: We identified a de novo missense variant in the coding region of the KCNB1 gene, c.49C>A which encodes a p.P17T mutation in the N-terminus of the voltage-gated, KV2.1 potassium channel. Electrophysiological studies measuring the impact of the variant on the functional properties of the channel, identified a gain of current, rightward shifts in the steady-state inactivation curve and reduced sensitivity to the blocker, guanxitoxin-1E. Interpretation: The clinical evaluation of this KCNB1 mutation describes a novel variant that is associated with global developmental delays, mild hypotonia and joint laxity, but without seizures. Most of the phenotypic features described are reported for other variants of the KCNB1 gene. However, the absence of early-onset epileptic disorders is a much less common occurrence. This lack of seizure activity may be because other variants reported have resulted in loss-of-function of the encoded KV2.1 potassium channel, whereas this variant causes a gain-of-function.

Gain and loss of TASK3 channel function and its regulation by novel variation cause KCNK9 imprinting syndrome.

BACKGROUND: Genomics enables individualized diagnosis and treatment, but large challenges remain to functionally interpret rare variants. To date, only one causative variant has been described for KCNK9 imprinting syndrome (KIS). The genotypic and phenotypic spectrum of KIS has yet to be described and the precise mechanism of disease fully understood. METHODS: This study discovers mechanisms underlying KCNK9 imprinting syndrome (KIS) by describing 15 novel KCNK9 alterations from 47 KIS-affected individuals. We use clinical genetics and computer-assisted facial phenotyping to describe the phenotypic spectrum of KIS. We then interrogate the functional effects of the variants in the encoded TASK3 channel using sequence-based analysis, 3D molecular mechanic and dynamic protein modeling, and in vitro electrophysiological and functional methodologies. RESULTS: We describe the broader genetic and phenotypic variability for KIS in a cohort of individuals identifying an additional mutational hotspot at p.Arg131 and demonstrating the common features of this neurodevelopmental disorder to include motor and speech delay, intellectual disability, early feeding difficulties, muscular hypotonia, behavioral abnormalities, and dysmorphic features. The computational protein modeling and in vitro electrophysiological studies discover variability of the impact of KCNK9 variants on TASK3 channel function identifying variants causing gain and others causing loss of conductance. The most consistent functional impact of KCNK9 genetic variants, however, was altered channel regulation. CONCLUSIONS: This study extends our understanding of KIS mechanisms demonstrating its complex etiology including gain and loss of channel function and consistent loss of channel regulation. These data are rapidly applicable to diagnostic strategies, as KIS is not identifiable from clinical features alone and thus should be molecularly diagnosed. Furthermore, our data suggests unique therapeutic strategies may be needed to address the specific functional consequences of KCNK9 variation on channel function and regulation.