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Fahima Syeda, Andrew P Holmes, Ting Y Yu, Samantha Tull, Stefan Michael Kuhlmann, Davor Pavlovic, Daniel Betney, Genna Riley, Jan P Kucera, Florian Jousset, Joris R de Groot, Stephan Rohr, Nigel A Brown, Larissa Fabritz, Paulus Kirchhof
BACKGROUND: Antiarrhythmic drugs are widely used to treat patients with atrial fibrillation (AF), but the mechanisms conveying their variable effectiveness are not known. Recent data suggested that paired like homeodomain-2 transcription factor (PITX2) might play an important role in regulating gene expression and electrical function of the adult left atrium (LA). OBJECTIVES: After determining LA PITX2 expression in AF patients requiring rhythm control therapy, the authors assessed the effects of Pitx2c on LA electrophysiology and the effect of antiarrhythmic drugs...
October 25, 2016: Journal of the American College of Cardiology
Ursula Ravens, Katja E Odening
Despite the epidemiological scale of atrial fibrillation, current treatment strategies are of limited efficacy and safety. Ideally, novel drugs should specifically correct the pathophysiological mechanisms responsible for atrial fibrillation with no other cardiac or extracardiac actions. Atrial-selective drugs are directed toward cellular targets with sufficiently different characteristics in atria and ventricles to modify only atrial function. Several potassium (K(+)) channels with either predominant expression in atria or distinct electrophysiological properties in atria and ventricles can serve as atrial-selective drug targets...
October 12, 2016: Pharmacology & Therapeutics
Luis Marenco, Rixin Wang, Robert McDougal, Tsviya Olender, Michal Twik, Elspeth Bruford, Xinyi Liu, Jian Zhang, Doron Lancet, Gordon Shepherd, Chiquito Crasto
We present here an exploration of the evolution of three well-established, web-based resources dedicated to the dissemination of information related to olfactory receptors (ORs) and their functional ligands, odorants. These resources are: the Olfactory Receptor Database (ORDB), the Human Olfactory Data Explorer (HORDE) and ODORactor. ORDB is a repository of genomic and proteomic information related to ORs and other chemosensory receptors, such as taste and pheromone receptors. Three companion databases closely integrated with ORDB are OdorDB, ORModelDB and OdorMapDB; these resources are part of the SenseLab suite of databases (http://senselab...
2016: Database: the Journal of Biological Databases and Curation
Aymeric Monteillier, Alexandre Loucif, Kiyoyuki Omoto, Edward B Stevens, Sergio L Vicente, Pierre-Philippe Saintot, Lishuang Cao, David C Pryde
TRESK (Twik RElated Spinal cord K(+) channel) is a member of the Twin Pore Domain potassium channel (K2P) family responsible for regulating neuronal excitability in dorsal root ganglion (DRG) and trigeminal (TG) neurons, peripheral neurons involved in pain transmission. As channel opening causes an outward K(+) current responsible for cell hyperpolarisation, TRESK represents a potentially interesting target for pain treatment. However, as no crystal structure exists for this protein, the mechanisms involved in the opening action of its ligands are still poorly understood, making the development of new potent and selective openers challenging...
October 15, 2016: Bioorganic & Medicinal Chemistry Letters
Pyung Sun Cho, Han Kyu Lee, Sang Hoon Lee, Jay Zoon Im, Sung Jun Jung
The analgesic mechanism of opioids is known to decrease the excitability of substantia gelatinosa (SG) neurons receiving the synaptic inputs from primary nociceptive afferent fiber by increasing inwardly rectifying K(+) current. In this study, we examined whether a µ-opioid agonist, [D-Ala2,N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO), affects the two-pore domain K(+) channel (K2P) current in rat SG neurons using a slice whole-cell patch clamp technique. Also we confirmed which subtypes of K2P channels were associated with DAMGO-induced currents, measuring the expression of K2P channel in whole spinal cord and SG region...
September 2016: Korean Journal of Physiology & Pharmacology
Hyun Jong Kim, Joohan Woo, Yuran Nam, Joo Hyun Nam, Woo Kyung Kim
Pyrazole derivatives were originally suggested as selective blockers of the transient receptor potential cation 3 (TRPC3) and channel. In particular, pyr3 and 10 selectively inhibit TRPC3, whereas pyr2 (BTP2) and 6 inhibit ORAI1. However, their effects on background K(+) channel activity have not been elucidated. In this study, the effects of BTP2, pyr3, pyr6, and pyr10 were studied on cloned human TWIK-related K(+) channels (TREKs) and TWIK-related acid-sensitive K(+) channel 2 (TASK-2) channels, which modulate Ca(2+) signaling by controlling membrane potential, in HEK293T-overexpressing cells by using a whole-cell patch clamp technique...
August 26, 2016: European Journal of Pharmacology
Victoria Oakes, Simone Furini, David Pryde, Carmen Domene
Potassium channels in the two-pore domain family (K2P) have various structural attributes that differ from those of other K(+) channels, including a dimeric assembly constituted of nonidentical domains and an expansive extracellular cap. Crystallization of the prototypical K2P channel, TWIK-1, finally revealed the structure of these characteristics in atomic detail, allowing computational studies to be undertaken. In this study, we performed molecular-dynamics simulations for a cumulative time of ∼1 μs to discern the mechanism of ion transport throughout TWIK-1...
August 23, 2016: Biophysical Journal
Kun Wang, Xiangang Kong
This study aimed to explore the neuroprotection and mechanism of isoflurane on rats with spinal cord ischemic injury. Total 40 adult male Sprague-Dawley rats were divided into the four groups (n=10). Group A was sham-operation group; group B was ischemia group; group C was isoflurane preconditioning group; group D was isoflurane preconditioning followed by ischemia treatment group. Then the expressions of TWIK-related K⁺ channel 1 (TREK1) in the four groups were detected by immunofluorescent assay, real time-polymerase chain reactions (RT-PCR) and western blot...
September 1, 2016: Biomolecules & Therapeutics
Hyun Park, Eun-Jin Kim, Jaehee Han, Jongwoo Han, Dawon Kang
TWIK-related K(+) channel-2 (TREK-2) and TWIK-related spinal cord K(+) (TRESK) channel are members of two-pore domain K(+) channel family. They are well expressed and help to set the resting membrane potential in sensory neurons. Modulation of TREK-2 and TRESK channels are involved in the pathogenesis of pain, and specifi c activators of TREK-2 and TRESK may be benefi cial for the treatment of pain symptoms. However, the effect of commonly used analgesics on TREK-2 and TRESK channels are not known. Here, we investigated the effect of analgesics on TREK-2 and TRESK channels...
July 2016: Korean Journal of Physiology & Pharmacology
Gil Stelzer, Inbar Plaschkes, Danit Oz-Levi, Anna Alkelai, Tsviya Olender, Shahar Zimmerman, Michal Twik, Frida Belinky, Simon Fishilevich, Ron Nudel, Yaron Guan-Golan, David Warshawsky, Dvir Dahary, Asher Kohn, Yaron Mazor, Sergey Kaplan, Tsippi Iny Stein, Hagit N Baris, Noa Rappaport, Marilyn Safran, Doron Lancet
BACKGROUND: Next generation sequencing (NGS) provides a key technology for deciphering the genetic underpinnings of human diseases. Typical NGS analyses of a patient depict tens of thousands non-reference coding variants, but only one or very few are expected to be significant for the relevant disorder. In a filtering stage, one employs family segregation, rarity in the population, predicted protein impact and evolutionary conservation as a means for shortening the variation list. However, narrowing down further towards culprit disease genes usually entails laborious seeking of gene-phenotype relationships, consulting numerous separate databases...
2016: BMC Genomics
Ambily Nath Indu Viswanath, Seo Yun Jung, Eun Mi Hwang, Ki Duk Park, Sang Min Lim, Sun-Joon Min, Yong Seo Cho, Ae Nim Pae
TREK1 (Twik-RElated Potassium (K(+) ) channel 1), though a well characterized target for several neuropsychiatric disorders, underwent very few explorations for prototypic inhibitors. This study aimed to find diverse chemotypes by an in silico means. Homology-built TREK1 on docking with high affinity quaternary ammonium compounds (QAs) corroborated the previous findings by recreating the binding mode with proximally positioned key residues: Thr157, Thr266, Ile182, Leu189, and Leu304. Physical interactions between TREK1 and known antagonists were modeled to compensate the lack of ligand-bound protein crystal structures...
June 26, 2016: Chemical Biology & Drug Design
Gil Stelzer, Naomi Rosen, Inbar Plaschkes, Shahar Zimmerman, Michal Twik, Simon Fishilevich, Tsippi Iny Stein, Ron Nudel, Iris Lieder, Yaron Mazor, Sergey Kaplan, Dvir Dahary, David Warshawsky, Yaron Guan-Golan, Asher Kohn, Noa Rappaport, Marilyn Safran, Doron Lancet
GeneCards, the human gene compendium, enables researchers to effectively navigate and inter-relate the wide universe of human genes, diseases, variants, proteins, cells, and biological pathways. Our recently launched Version 4 has a revamped infrastructure facilitating faster data updates, better-targeted data queries, and friendlier user experience. It also provides a stronger foundation for the GeneCards suite of companion databases and analysis tools. Improved data unification includes gene-disease links via MalaCards and merged biological pathways via PathCards, as well as drug information and proteome expression...
2016: Current Protocols in Bioinformatics
Joohan Woo, Dong Hoon Shin, Hyun Jong Kim, Hae Young Yoo, Yin-Hua Zhang, Joo Hyun Nam, Woo Kyung Kim, Sung Joon Kim
TWIK-related two-pore domain K(+) channels 1 and 2 (TREKs) are activated under various physicochemical conditions. However, the directions in which they are regulated by PI(4,5)P2 and intracellular ATP are not clearly presented yet. In this study, we investigated the effects of ATP and PI(4,5)P2 on overexpressed TREKs (HEK293T and COS-7) and endogenously expressed TREK-2 (mouse astrocytes and WEHI-231 B cells). In all of these cells, both TREK-1 and TREK-2 currents were spontaneously increased by dialysis with ATP-free pipette solution for whole-cell recording (ITREK-1,w-c and ITREK-2w-c) or by membrane excision for inside-out patch clamping without ATP (ITREK-1,i-o and ITREK-2,i-o)...
August 2016: Pflügers Archiv: European Journal of Physiology
Christian Jorgensen, Leonardo Darré, Victoria Oakes, Rubben Torella, David Pryde, Carmen Domene
Potassium channels are of paramount physiological and pathological importance and therefore constitute significant drug targets. One of the keys to rationalize the way drugs modulate ion channels is to understand the ability of such small molecules to access their respective binding sites, from which they can exert an activating or inhibitory effect. Many computational studies have probed the energetics of ion permeation, and the mechanisms of voltage gating, but little is known about the role of fenestrations as possible mediators of drug entry in potassium channels...
July 5, 2016: Molecular Pharmaceutics
Miklós Lengyel, Gábor Czirják, Péter Enyedi
Two-pore domain (K2P) potassium channels are the major molecular correlates of the background (leak) K(+) current in a wide variety of cell types. They generally play a key role in setting the resting membrane potential and regulate the response of excitable cells to various stimuli. K2P channels usually function as homodimers, and only a few examples of heteromerization have been previously reported. Expression of the TREK (TWIK-related K(+) channel) subfamily members of K2P channels often overlaps in neurons and in other excitable cells...
June 24, 2016: Journal of Biological Chemistry
Alex Hørby Christensen, Franck C Chatelain, Inken G Huttner, Morten Salling Olesen, Magdalena Soka, Sylvain Feliciangeli, Claire Horvat, Celine F Santiago, Jamie I Vandenberg, Nicole Schmitt, Søren-Peter Olesen, Florian Lesage, Diane Fatkin
The two-pore domain potassium (K(+)) channel TWIK-1 (or K2P1.1) contributes to background K(+) conductance in diverse cell types. TWIK-1, encoded by the KCNK1 gene, is present in the human heart with robust expression in the atria, however its physiological significance is unknown. To evaluate the cardiac effects of TWIK-1 deficiency, we studied zebrafish embryos after knockdown of the two KCNK1 orthologues, kcnk1a and kcnk1b. Knockdown of kcnk1a or kcnk1b individually caused bradycardia and atrial dilation (p<0...
August 2016: Journal of Molecular and Cellular Cardiology
Sandy Blin, Ismail Ben Soussia, Eun-Jin Kim, Frédéric Brau, Dawon Kang, Florian Lesage, Delphine Bichet
The tandem of pore domain in a weak inwardly rectifying K(+) channel (Twik)-related acid-arachidonic activated K(+) channel (TRAAK) and Twik-related K(+) channels (TREK) 1 and TREK2 are active as homodimers gated by stretch, fatty acids, pH, and G protein-coupled receptors. These two-pore domain potassium (K2P) channels are broadly expressed in the nervous system where they control excitability. TREK/TRAAK KO mice display altered phenotypes related to nociception, neuroprotection afforded by polyunsaturated fatty acids, learning and memory, mood control, and sensitivity to general anesthetics...
April 12, 2016: Proceedings of the National Academy of Sciences of the United States of America
Joshua Levitz, Perrine Royal, Yannick Comoglio, Brigitte Wdziekonski, Sébastien Schaub, Daniel M Clemens, Ehud Y Isacoff, Guillaume Sandoz
Twik-related K(+) channel 1 (TREK1), TREK2, and Twik-related arachidonic-acid stimulated K(+) channel (TRAAK) form the TREK subfamily of two-pore-domain K(+) (K2P) channels. Despite sharing up to 78% sequence homology and overlapping expression profiles in the nervous system, these channels show major differences in their regulation by physiological stimuli. For instance, TREK1 is inhibited by external acidification, whereas TREK2 is activated. Here, we investigated the ability of the members of the TREK subfamily to assemble to form functional heteromeric channels with novel properties...
April 12, 2016: Proceedings of the National Academy of Sciences of the United States of America
Felix Wiedmann, Constanze Schmidt, Patrick Lugenbiel, Ingo Staudacher, Ann-Kathrin Rahm, Claudia Seyler, Patrick A Schweizer, Hugo A Katus, Dierk Thomas
The improvement of treatment strategies in cardiovascular medicine is an ongoing process that requires constant optimization. The ability of a therapeutic intervention to prevent cardiovascular pathology largely depends on its capacity to suppress the underlying mechanisms. Attenuation or reversal of disease-specific pathways has emerged as a promising paradigm, providing a mechanistic rationale for patient-tailored therapy. Two-pore-domain K(+) (K(2P)) channels conduct outward K(+) currents that stabilize the resting membrane potential and facilitate action potential repolarization...
May 2016: Clinical Science (1979-)
Yixing Du, Conrad M Kiyoshi, Qi Wang, Wei Wang, Baofeng Ma, Catherine C Alford, Shiying Zhong, Qi Wan, Haijun Chen, Eric E Lloyd, Robert M Bryan, Min Zhou
We have recently shown that a linear current-to-voltage (I-V) relationship of membrane conductance (passive conductance) reflects the intrinsic property of K(+) channels in mature astrocytes. While passive conductance is known to underpin a highly negative and stable membrane potential (V M) essential for the basic homeostatic function of astrocytes, a complete repertoire of the involved K(+) channels remains elusive. TREK-1 two-pore domain K(+) channel (K2P) is highly expressed in astrocytes, and covalent association of TREK-1 with TWIK-1, another highly expressed astrocytic K2P, has been reported as a mechanism underlying the trafficking of heterodimer TWIK-1/TREK-1 channel to the membrane and contributing to astrocyte passive conductance...
2016: Frontiers in Cellular Neuroscience
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