Ms Emma Veale
Medway School of Pharmacy
- +44 (0)1634 20 2960
The research focus of Professor Alistair Mathie’s laboratory has been the study of neuronal potassium channels, understanding their function and regulation and determining their roles in controlling the excitability and firing of mammalian cells, particularly neurons. In particular, the focus of the past 10 years has been the investigation of two-pore domain potassium (K2P) channels and their modulation by various pharmacological agents, physiological mediators and neurotransmitter substances.
The laboratory utilises a variety of different techniques to study the properties of ion channels, including whole-cell patch clamp electrophysiology, molecular biology (PCR, site-directed mutagenesis, sub-cloning), fluorescent imagining, tissue culture and computer modelling.
As well as studying the structural, functional and expression properties of these K2P channels, they have a major interest in investigating the role of K2P’s in a range of diverse physiological and pathophysiological conditions, including depression, pain, KCNK9 imprinting syndrome – Birk Barel and Balkan Endemic Nephropathy, which has led to publications in high impact journals (see publication list for more details). As a direct result of this work, one activator has been adopted in a trial in the USA for use in the treatment of “KCNK9 imprinting syndrome”, a disease resulting from the mutation of the potassium channel, TASK3.
A number of Emma’s research projects are also carried out in collaboration with the pharmaceutical industry (MRC Technology, Pfizer, Takeda, Galleon) and academic laboratories in the UK, Germany, USA and Australia.
Emma and Professor Mathie have recently presented (BPS) and published work (British Journal of Pharmacology) related to the plant extract Aristolochic acid and its regulation of K2P channels and associated link to Balkan Endemic Nephropathy (BEN).
Aristolochic Acid is a potent regulator of K2P Channels
Aristolochic acid (AristA) is found in the plants of Aristolochiaceae and used in traditional herbal medicines for the treatment of pain including child birth, headache, back pain, joint pain and anxiety (Scarborough J, 2011, Pharmacy in History, 53, 3-21). Low-level exposure to AristA through the contamination of wheat flour from seeds of Aristolochia clematitis is thought to cause the renal disease restricted to rural areas of the Balkans, known as Balkan Endemic Nephropathy (BEN) (Grollman, 2007, PNAS, 104, 12129-12134). A number of patients predisposed to BEN have been shown to carry a mutation of the physiological important renal K2P channel, TASK2 (Toncheva et al., 2014, Biomed Res Int., 920723).
Figure 1: Adapted from front cover image by Gebhart, K (2012). Kidnet Int., 81 (6).
Emma’s research looked at the effect of AristA on TASK2 and mutant TASK2 (T108P) channels. She found that the mutated channel was non-functional and like wild type TASK2 was unaffected by high concentrations of AristA (see Figure 2 and Veale & Mathie, 2016, Br. J. Pharm).
Figure 2: AristA (300 μM) had a limited effect on TASK2_T108P mutated channels.
However, screening of other K2P channels, showed that AristA modestly enhanced TREK1 and TREK2 channels, but more interestingly was a potent inhibitor of TRESK channels (see Figure 3).
Figure 3: AristA (100 μM) is a potent inhibitor of TRESK channels, with a 50% effective concentration of 13 μM (95% confidence intervals 11-18μM) and a Hill slope of 0.56 (95% confidence intervals 0.43 – 0.65).
Emma has shown that AristA involvement in BEN is unlikely due to a direct effect on the TASK2 channels. Rather that loss of functional TASK2 channels in BEN may increase susceptibility to AristA toxicity. However, AristA is a potent inhibitor of an unrelated K2P channel, TRESK. What function this has is not yet known, but will become the focus of future research in the lab.
Emma and Professor Mathie have also been awarded a Kent 50th Scholarship to investigate the role of potassium channels in pulmonary hypertension following HIV infection. This work is being carried out by Kevin Cunningham.
Potassium Channels in Pulmonary Hypertension
Pulmonary arterial hypertension (PAH) is a rare disease, characterised by high blood pressure in the lungs and with high mortality rates. Recently genetic mutations of the two-pore domain potassium channel, TASK1, have been identified by whole-exome sequencing and linked to PAH (Ma et al., 2013, NEJM 369, 351-361). The first channelopathy to be identified in PAH (see Figure 1).
Figure 1: Topologic analysis of the human TASK1 (KCNK3) channel, indicating the positions of the mutations that were identified in this study (Ma et al., 2013, NEJM 369, 351-361).
HIV infected patients have a >10 fold higher incidence of pulmonary hypertension compared to the general population (Syed & Sani, 2013, Heart, 99, 1146-1153), however the reason(s) underlying this is not clear. It has been shown that there is significant structural homology between the HIV-1 accessory protein Vpu and the N-terminus of TASK1 and that the two proteins interact to disrupt each other’s function (Hsu et al., 2004, Mol. Cell, 23, 259-267; Veale and Mathie unpublished observations). In this project, we aim to determine the importance of this interaction in altering the functional properties of pulmonary arterial smooth muscle cells (PASMCs). This work is part of a larger international collaborative initiative to understand the mechanisms underlying the increased risk of PAH, following HIV infection.
Emma and Alistair have been awarded, in collaboration with academics at the University of Greenwich, a prestigious Vice Chancellor’s Research Scholarship to develop the use of amphipathic styrene maleic acid copolymers (SMAs) technology, to extract K2P channels directly from biological membranes in the form of polymer-bounded “nanodiscs” and to characterise them in association with putative therapeutic agents.
Development of nanodisc technology
The characterization of the biochemical and biophysical properties of membrane proteins (MPs) is hampered by their requirement to reside in the lipid bilayer for their correct function. Maintaining the protein’s natural conformation on extraction from the bilayer, during purification, is extremely challenging. The high cost, low success rate and lack of information on the large extracellular and intracellular loops of the K2P channels, missing from existing crystal structures, means that an alternative method of purifying MPs is imperative. Recently a detergent-free approach has been described using amphipathic styrene maleic acid copolymers (SMAs) to solubilize MPs directly from biological membranes in the form of polymer-bounded nanodiscs (see Figure 1).
Figure 1: Extraction of membrane proteins with native lipid environment by SMA. SMA additions leads to the formation of native nanodiscs containing different membrane spanning proteins. Subsequent affinity purification allows for the isolation of native nanodiscs with the protein of interest (Dörr et al., 2016, Eur. Biophys. J., 45, 3-21).
Emma is also currently investigating the role of Kozak consensus sequences and the impact of Alternative Translation Initiation (ATI) on K2P channel expression and their regulation by known therapeutic agents.
Role of Kozak Consensus Sequences and Alternative Translation Initiation of K2P Channel expression and regulation
The process of alternative translational initiation (ATI) of “leaky” scanning occurs when the ribosome skips the first translation initiation start codon (TIC) and begins translating the protein from the next available TIC, reducing translational efficiency. The reason this occurs is thought to correspond with the initial TIC being embedded within a non-suitable recognition sequence, also known as the Kozak consensus sequence (see Figure 1). From a study of over 10,000 human genes, 50% of the human mRNA’s were found to carry a purine (A or G) at position -3 of the Kozak consensus sequence, whilst 40% have a G at position +4 (see Figure 1). The greater the distance between a TIC and the next downstream in-frame ATG codon, increases the likelihood of that gene harbouring a TIC mutation, and having clinical relevance (Wolf et al., 2011, Hum Mut., 32, 1137-1143). More than 400 unique base-pair substitutions, located within the TICs of 255 different genes, and reported to cause genetic disease have been reported in the Human Gene Mutation Database (HGMD).
TASK1 which is increasingly being associated with particular disease states including pulmonary arterial hypertension and atrial arrhythmias (Ma et al., 2013, NEJM 369, 351-361; Liang et al., 2014, J. Mol. Cell. Cardiol., 67, 69-76). Until recently ATI has been restricted to the TREK family of K2P channels (Thomas et al., 2008, Neuron, 58, 859-870; Simkin et al., 2008, J. Phys., 23, 5651-5663), however recently (Liang et al., 2014), found genetic variants in the 5’UTR region of TASK1 in a small number of patients with familial atrial fibrillation (see Figure 1). These variants occur within the Kozak consensus sequence of the channel at -4 and -3 and conferred a “weak” consensus and poor translational efficiency.
Figure 1: Sequence logo plot of Kozak consensus sequence around AUG start codons in human mRNA. Relative abundance and extent of conservation are indicated by the height of each nucleotide. Shown below is the corresponding region of TASK-1 mRNA and identified sequence variants (Liang et al., 2014, J. Mol. Cell. Cardiol., 67, 69-76).
- Veale EL, Mathie A (2016). Aristolochic acid, a plant extract used in the treatment of pain and linked to Balkan Endemic Nephropathy, is a regulator of K2P channels. Br J Pharmacol. DOI:10.111/bph.13465.
- Mathie A, Veale EL (2015). Two-pore domain potassium channels: Potential therapeutic targets for the treatment of pain. Pflug Arch Eur J Physiol. 467, 5, 931-943
- Veale EL, Al Moubarak E, Bajaria N, Omoto K, Cao L, Tucker SJ, Stevens EB, Mathie A (2014). Influence of the N-terminus on the Biophysical Properties and Pharmacology of TREK1 Potassium Channels. Mol Pharmacol doi:10.1124/mol.113.091199.
- Veale EL, Hassan M, Walsh Y, Al Moubarak E, Mathie A (2014). Recovery of current through mutated TASK3 potassium channels underlying Birk Barel syndrome. Mol Pharmacol 85: 397-407.
- El Hachmane MF, Rees KA, Veale EL, Sumbayev VV, Mathie A (2014). Enhancement of TWIK-related acid sensitive potassium channel 3 (TASK3) two pore domain potassium channel activity by TNFa. J Biol Chem 289: 1388-1401.
- Veale EL, Rees KA, Mathie A, Trapp S (2010). Dominant negative effects of a non-functional TREK1 splice variant expressed in brain. J Biol Chem 285: 29295-29304.
- Mathie A, Al Moubarak E, Veale EL (2010). Gating of two pore domain potassium channels. J Physiol 588: 3149-3156.
- Mathie A, Rees KA, El Hachmane MF, Veale EL (2010). Trafficking of neuronal two pore domain potassium channels. Curr Neuropharmacol 8: 276-286.
- Cao L, Veale EL, Mathie A, Stevens E (2010). Differential modulation of TREK-1, TASK-3 and TRESK K2P ion channels by BL-1249. Program No. 174.6/KK13. 2010 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2010. Online.
- Rees KA, Veale EL, Mathie A (2010). Stimulation of heteromeric TASK channel trafficking by 14-3-3(beta) protein. Basic and Clinical Pharmacology & Toxicology 107 (Suppl. 1), 119.
Full List of Refereed Papers
- Clarke CE, Veale EL*, Wyse K, Vandenberg JI, Mathie A (2008). The M1P1 loop of TASK3 K2P channels apposes the selectivity filter and influences channel function. J Biol Chem 283: 16985-16992. * joint first author.
- Mathie A, Veale EL (2008). Neuronal Potassium Channels. In Encyclopedia of Neuroscience: 2792-2797. eds. Binder M, Hirokawa N, Windhorst U, Hirsch MC, Springer-Verlag (Berlin).
- Veale EL, Aller MI, Mathie A (2008). Functional characteristics and regulation of mouse THIK1 two-pore-domain potassium channels. Acta Physiol Sinica 60 S1: 229.
- Veale EL, Buswell R, Clarke CE, Mathie A (2007). Identification of a region in the TASK3 two pore domain potassium channel that is critical for its blockade by methanandamide. Br J Pharmacol 152: 778-786.
- Brickley SG, Aller MI, Sandu C, Veale EL, Alder FG, Sambi H, Mathie A, Wisden W (2007). TASK-3 two-pore domain potassium channels enable sustained high-frequency firing in cerebellar granule neurons. J Neurosci 27: 9329-9340.
- Mathie A, Veale EL (2007). Therapeutic potential of neuronal two pore domain potassium channel modulators. Curr Opin Invest Drugs 8: 555-562.
- Veale EL, Kennard LE, Sutton GL, MacKenzie G, Sandu C, Mathie A (2007). G(alpha)q mediated regulation of TASK3 two pore domain potassium channels: the role of protein kinase C. Mol Pharmacol 71: 1666-1675.
- Veale EL, Buswell R, Clarke CE, Mathie A (2007). Identification of a region in the TASK3 two pore domain potassium channel that is critical for its blockade by methanandamide. Brit J Pharmacol advanced online publication doi:10.1038/sj.bjp.0707436.
- Brickley SG, Aller MI, Sandu C, Veale EL, Alder FG, Sambi H, Mathie A, Wisden W (2007). TASK-3 two-pore domain potassium channels enable sustained high-frequency firing in cerebellar granule neurons. J Neurosci 27:9329-9340.
- Mathie A, Veale EL (2007). Therapeutic potential of neuronal two-pore domain potassium-channel modulators. Curr Opin Investig Drugs 8:555-562.
- Veale EL, Kennard LE, Sutton GL, MacKenzie G, Sandu C, Mathie A (2007). G(alpha)q-mediated regulation of TASK3 two-pore domain potassium channels: the role of protein kinase C. Mol Pharmacol 71:1666-1675.
- Mathie A, Sutton GL, Clarke CE, Veale EL (2006). Zinc and copper: pharmacological probes and endogenous modulators of neuronal excitability. Pharmacol Ther 111:567-583.
- Linden AM, Aller MI, Leppa E, Vekovischeva O, Aitta-Aho T, Veale EL, Mathie A, Rosenberg P, Wisden W, Korpi ER (2006). The contributions of TASK-1-containing channels to the actions of inhalation anesthetics, the alpha(2) adrenergic sedative dexmedetomidine, and cannabinoid agonists. J Pharmacol Exp Ther 317:615-626.
- Aller MI, Veale EL, Linden AM, Sandu C, Schwaninger M, Evans LJ, Korpi ER, Mathie A, Wisden W, Brickley SG (2005). Modifying the subunit composition of TASK channels alters the modulation of a leak conductance in cerebellar granule neurons. J Neurosci 25:11455-11467.
- Kennard LE, Chumbley JR, Ranatunga KM, Armstrong SJ, Veale EL, Mathie A (2005). Inhibition of the human two-pore domain potassium channel, TREK-1, by fluoxetine and its metabolite norfluoxetine. Br J Pharmacol 144:821-829.
- Clarke CE, Veale EL, Green PJ, Meadows HJ, Mathie A (2004). Selective block of the human 2-P domain potassium channel, TASK-3, and the native leak potassium current, IKSO, by zinc. J Physiol 560:51-62.
- Mathie A, Clarke CE, Ranatunga KM, Veale EL (2003). What are the roles of the many different types of potassium channel expressed in cerebellar granule cells? Cerebellum 2:11-25.
Refereed Conference Contributions
- Veale EL, Mathie A (2015) Aristolochic acid, a plant extract used in the treatment of pain, is a potent regulator of K2P channels. Proceedings of the British Pharmacological Society, www.pA2online.org/abstracts/vol13 in press.
- Mathie A, Veale EL (2015) A mutation of TASK2 K2P channels (T108P), found in certain patients predisposed to Balkan Endemic Nephropathy, reduces TASK2 current density and alters ion selectivity. Proceedings of the British Pharmacological Society, www.pA2online.org/abstracts/vol13 in press.
- Loucif AJ, Saintot P-P, Liu J, Antonio BM, Zellmer SG, Veale EL, Mathie A, Cao L, Castle NA, Stevens EB (2015). A newly identified selective mechano-sensitive K2P opener reduces rat dorsal root ganglion (DRG) neurone excitability. Society for Neuroscience (USA) annual meeting, Chicago.
- Mathie A, Veale EL (2014). Pharmacological and genetic recovery of current through truncated and mutated K2P channels. Acta Physiologica 211 (S697): 39P.
- Hassan M, Walsh Y, Al-Moubarak E, Frimpong S, Golledge R, Kehoe B, Prestwich S, Rothou D, Sutcliffe D, Mathie A, Veale EL (2014). Inward Rectification of Birk Barel mutated human and mouse TASK3 potassium channels. Physiology 2014, PCB053.
- Al Moubarak E, Veale, EL, Mathie A (2013). Regulation of TREK1 two pore domain potassium channels by amitriptyline. IUPS 2013 PCD131.
- Al Moubarak E, Veale, EL, Mathie A (2013). Regulation of TREK1 two pore domain potassium channels by citalopram. FASEB J 27: 913.31.
- Rees KA, Veale EL, Mathie A (2011). Modulation of surface expression of two pore domain potassium channels by N-linked glycosylation. NCMLS 5th New Frontiers Symposium: Ion channels in health and disease. P25.
- Cao L, Veale EL, Mathie A, Stevens E (2010). Differential modulation of TREK-1, TASK-3 and TRESK K2P ion channels by BL-1249. Program No. 174.6/KK13. 2010 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience Online.
- Rees KA, Veale EL, Mathie A (2010). Stimulation of heteromeric TASK channel trafficking by 14-3-3β protein. Basic and Clinical Pharmacology & Toxicology 107 (Suppl. 1), 119.
Full List of Refereed Conference Contributions
- Veale EL, Aller MI, Mathie A (2008). Functional characteristics and regulation of mouse THIK1 two-pore-domain potassium channels. Beijing Joint Conference of Physiological Sciences 2008, Acta Physiol Sinica 60 S1: 229.
- Clarke CE, Veale EL, Mathie A, Wyse, K, Torres A, Pages G, Kuchel PW, Vandenberg JI (2007). A link to two-pore domain potassium channel regulation. AuPS Proceedings 38: 36P
- Veale EL, Clarke CE, Mathie A (2007). Identification of a region of TASK3 two pore domain K channels critical for their modulation by methanandamide. Life Sci Conference (Glasgow): PC187.
- Brickley SG, Aller MI, Veale EL, Sandu C, Alder FG, Sambi H, Mathie A, Wisden W (2007). Two-pore domain potassium channels enable sustained high-frequence firing. Brit Neurosci Assoc Abstr 19: P87.
- Aller MI, Brickley SG, Mathie A, Sandu C, Veale EL, Wisden W (2006). Two-pore potassium channel expression enables sustained high-frequency firing. FENS Abstr 3: A189.1.
- Veale EL, Sutton GL, Mathie A (2006). Inhibition of TASK3 two pore domain potassium channels following activation of protein kinase C. Proc Physiol Soc 3: PC28.
- Evans LJ, Veale EL, Mathie A (2006). Differential inhibition of TASK K2P channels by copper. Acta Physiologica 186 (S1): 189P.
- Brickley SG, Veale EL, Aller MI, Linden A-M, Sandu C, Schwaninger M, Evans L, Korpi E, Wisden, W, Mathie A (2005). Modifying the subunit composition of TASK channels alters the modulation of a leak conductance in adult cerebellar granule neurons. Program No. 609.11. 2005 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience Online.
- Veale EL, Clarke CE, Mathie A (2005). A key glutamate residue (E30), conserved in many K channels, regulates the gating of TASK3 two pore domain potassium channels. J Physiol 567: PC196.
- Kennard LE, Veale EL, Mathie A (2005). Muscarinic inhibition of TASK-3 two-pore domain potassium channels. Biophys J 88: 2281-Pos.
- Veale EL, Clarke CE, Mathie A (2005). Block of TASK1 and TASK3 K2P channels by zinc: interactions with pHo and [K]o. J Physiol Biochem 61: 109-110.
- Kennard LE, Veale EL, Mathie A (2004). Inhibition of the human two-pore domain potassium channel, TREK1, by fluoxetine and its metabolite norfluoxetine. FENS Abstr 2: A082.9.
- Clarke CE, Green PJ, Veale EL, Meadows HJ, Mathie A (2003). The involvement of residues H98 and E70 in the block of the human two pore domain potassium channel, TASK-3, by zinc. J Physiol 547P: C46.
- Mathie A, Veale EL (2003). Voltage-gated ion channels. ICNIRP/WHO International Workshop on ELF Weak Electric Field Effects on the Body (National Radiological Protection Board, Oxford): 7-8.
- Mathie A, Clarke CE, Ranatunga KM, Veale EL (2003).Two-pore domain potassium channels in mammalian neurons. J Physiol 547P: SA7.
- Mathie A, Clarke CE, Kennard LE, Ranatunga KM, Veale EL (2003). Two-pore domain potassium channels and their role in the regulation of neuronal excitability. 3rd Federation of European Physiological Societies meeting (Nice): S23-1.
- Morris NP, Veale, E, Heintz N, Rudy B. & Robertson B (2003).Cerebellar Purkinje cell voltage-gated potassium currents are significantly reduced in Kv3.3 knockout mice. 16th Meeting of the British Neuroscience Association. 20.01.
- Morris NP, Veale E, Chiu SY & Robertson B (2002). Effects of subunit selective dendrotoxins on spontaneous inhibitory postsynaptic currents in cerebellar Purkinje cells of Kv1.1 null mutant mice. J.Physiol. 544 73P.
- Coombs ID, Veale EL & Robertson B (2001). External cations influence deactivation rates of the HCN-1 channel expressed in tSA cells. Biophys J. 82 578a.
- Veale E, Morris N, Fyffe R & Robertson B (2001). Electrophysiological and molecular characteristics of the hyperpolarization-activated cation current in the medial septum/diagonal band complex in the mouse. 34th International Union of Physiological Sciences Congress (Christchurch) 699.
- Whittle AJ, Coombs ID, Martin HGS, Veale EL & Robertson B (2000). Properties of the murine hyperpolarization-activated channel mHCN1 expressed in xenopus laevis oocytes. J.Physiol. 528 55-56P.
- Warren G, McKown R, Teutonico R, Kuroki G, Veale E & Sagen K (1997). Arabidposis mutants impaired in freezing tolerance after cold acclimation. in Plant Cold Hardiness. pp 45-56, Springer, New York
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