Publications by authors named "Alan D Wickenden"

40 Publications

Selective Targeting of Nav1.7 with Engineered Spider Venom-Based Peptides.

Channels (Austin) 2021 Dec;15(1):179-193

Molecular and Cellular Pharmacology, Janssen Research and Development, LLC , San Diego, CA, USA.

A fundamental mechanism that drives the propagation of electrical signals in the nervous system is the activation of voltage-gated sodium channels. The sodium channel subtype Nav1.7 is critical for the transmission of pain-related signaling, with gain-of-function mutations in Nav1.7 resulting in various painful pathologies. Loss-of-function mutations cause complete insensitivity to pain and anosmia in humans that otherwise have normal nervous system function, rendering Nav1.7 an attractive target for the treatment of pain. Despite this, no Nav1.7 selective therapeutic has been approved for use as an analgesic to date. Here we present a summary of research that has focused on engineering peptides found in spider venoms to produce Nav1.7 selective antagonists. We discuss the progress that has been made on various scaffolds from different venom families and highlight the challenges that remain in the effort to produce a Nav1.7 selective, venom-based analgesic.
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http://dx.doi.org/10.1080/19336950.2020.1860382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7808416PMC
December 2021

Functional α6β4 acetylcholine receptor expression enables pharmacological testing of nicotinic agonists with analgesic properties.

J Clin Invest 2020 11;130(11):6158-6170

The α6β4 nicotinic acetylcholine receptor (nAChR) is enriched in dorsal root ganglia neurons and is an attractive non-opioid therapeutic target for pain. However, difficulty expressing human α6β4 receptors in recombinant systems has precluded drug discovery. Here, genome-wide screening identified accessory proteins that enable reconstitution of human α6β4 nAChRs. BARP, an auxiliary subunit of voltage-dependent calcium channels, promoted α6β4 surface expression while IRE1α, an unfolded protein response sensor, enhanced α6β4 receptor assembly. Effects on α6β4 involve BARP's N-terminal region and IRE1α's splicing of XBP1 mRNA. Furthermore, clinical efficacy of nicotinic agents in relieving neuropathic pain best correlated with their activity on α6β4. Finally, BARP-knockout, but not NACHO-knockout mice lacked nicotine-induced antiallodynia, highlighting the functional importance of α6β4 in pain. These results identify roles for IRE1α and BARP in neurotransmitter receptor assembly and unlock drug discovery for the previously elusive α6β4 receptor.
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http://dx.doi.org/10.1172/JCI140311DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7598046PMC
November 2020

A computational approach yields selective inhibitors of human excitatory amino acid transporter 2 (EAAT2).

J Biol Chem 2020 03 20;295(13):4359-4366. Epub 2020 Feb 20.

Discovery Sciences, Janssen Research and Development, San Diego, California 92121.

Excitatory amino acid transporters (EAATs) represent a protein family that is an emerging drug target with great therapeutic potential for managing central nervous system disorders characterized by dysregulation of glutamatergic neurotransmission. As such, it is of significant interest to discover selective modulators of EAAT2 function. Here, we applied computational methods to identify specific EAAT2 inhibitors. Utilizing a homology model of human EAAT2, we identified a binding pocket at the interface of the transport and trimerization domain. We next conducted a high-throughput virtual screen against this site and identified a selective class of EAAT2 inhibitors that were tested in glutamate uptake and whole-cell electrophysiology assays. These compounds represent potentially useful pharmacological tools suitable for further exploration of the therapeutic potential of EAAT2 and may provide molecular insights into mechanisms of allosteric modulation for glutamate transporters.
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http://dx.doi.org/10.1074/jbc.AC119.011190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7105306PMC
March 2020

Comprehensive engineering of the tarantula venom peptide huwentoxin-IV to inhibit the human voltage-gated sodium channel hNa1.7.

J Biol Chem 2020 01 23;295(5):1315-1327. Epub 2019 Dec 23.

Molecular and Cellular Pharmacology, Janssen Research and Development, LLC, San Diego, California 92121.

Pain is a significant public health burden in the United States, and current treatment approaches rely heavily on opioids, which often have limited efficacy and can lead to addiction. In humans, functional loss of the voltage-gated sodium channel Na1.7 leads to pain insensitivity without deficits in the central nervous system. Accordingly, discovery of a selective Na1.7 antagonist should provide an analgesic without abuse liability and an improved side-effect profile. Huwentoxin-IV, a component of tarantula venom, potently blocks sodium channels and is an attractive scaffold for engineering a Na1.7-selective molecule. To define the functional impact of alterations in huwentoxin-IV sequence, we produced a library of 373 point mutants and tested them for Na1.7 and Na1.2 activity. We then combined favorable individual changes to produce combinatorial mutants that showed further improvements in Na1.7 potency (E1N, E4D, Y33W, Q34S-Na1.7 pIC = 8.1 ± 0.08) and increased selectivity over other Na isoforms (E1N, R26K, Q34S, G36I, Na1.7 pIC = 7.2 ± 0.1, Na1.2 pIC = 6.1 ± 0.18, Na1.3 pIC = 6.4 ± 1.0), Na1.4 is inactive at 3 μm, and Na1.5 is inactive at 10 μm We also substituted noncoded amino acids at select positions in huwentoxin-IV. Based on these results, we identify key determinants of huwentoxin's Na1.7 inhibition and propose a model for huwentoxin-IV's interaction with Na1.7. These findings uncover fundamental features of huwentoxin involved in Na1.7 blockade, provide a foundation for additional optimization of this molecule, and offer a basis for the development of a safe and effective analgesic.
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http://dx.doi.org/10.1074/jbc.RA119.011318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6996889PMC
January 2020

4-Methyl-6,7-dihydro-4H-triazolo[4,5-c]pyridine-Based P2X7 Receptor Antagonists: Optimization of Pharmacokinetic Properties Leading to the Identification of a Clinical Candidate.

J Med Chem 2017 06 25;60(11):4559-4572. Epub 2017 May 25.

Janssen Research & Development, LLC , 3210 Merryfield Row, San Diego, California 92121, United States.

The synthesis and preclinical characterization of novel 4-(R)-methyl-6,7-dihydro-4H-triazolo[4,5-c]pyridines that are potent and selective brain penetrant P2X7 antagonists are described. Optimization efforts based on previously disclosed unsubstituted 6,7-dihydro-4H-triazolo[4,5-c]pyridines, methyl substituted 5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazines, and several other series lead to the identification of a series of 4-(R)-methyl-6,7-dihydro-4H-triazolo[4,5-c]pyridines that are selective P2X7 antagonists with potency at the rodent and human P2X7 ion channels. These novel P2X7 antagonists have suitable physicochemical properties, and several analogs have an excellent pharmacokinetic profile, good partitioning into the CNS and show robust in vivo target engagement after oral dosing. Improvements in metabolic stability led to the identification of JNJ-54175446 (14) as a candidate for clinical development. The drug discovery efforts and strategies that resulted in the identification of the clinical candidate are described herein.
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http://dx.doi.org/10.1021/acs.jmedchem.7b00408DOI Listing
June 2017

Potentiating SLC transporter activity: Emerging drug discovery opportunities.

Biochem Pharmacol 2017 07 16;135:1-11. Epub 2017 Feb 16.

Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, San Diego, CA 92121, United States. Electronic address:

Maintaining the integrity of cellular membranes is critical to protecting metabolic activities and genetic information from the environment. Regulation of transport across membranes of essential chemicals, including water, nutrients, hormones and many drugs, is therefore key to cellular homeostasis and physiological processes. The two main transporter superfamilies are ATP-binding cassette (ABC) transporters that primarily function as efflux transporters, and the solute carrier (SLC) transporters. SLC transporters encompass 52 gene families with almost 400 different human transporter genes. Although long under-explored, SLC transporters are an emerging drug target class and the molecular target of several approved inhibitor drugs, such as selective serotonin reuptake inhibitors (SSRIs) for depression and sodium/glucose co-transporter (SGLT2) inhibitors for diabetes. Interestingly though, although loss-of-function mutations in numerous human SLC transporters are linked to Mendelian diseases, few reports of SLC transporter activators have appeared, and only inhibitors have been advanced to clinical studies. In this commentary, we discuss several strategies for potentiating SLC transporter function, from direct acting potentiators to modulators of transcription, translation or trafficking. We review the progress made in recent years toward the understanding of the structural and molecular basis of SLC transporter function and the pathways and mechanisms that regulate SLC expression, and describe the opportunities these new insights present for discovery of SLC transporter potentiators. Finally, we highlight the challenges associated with the various approaches and provide some thoughts on future directions that might facilitate the search for SLC potentiators with therapeutic potential.
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http://dx.doi.org/10.1016/j.bcp.2017.02.010DOI Listing
July 2017

T Cell Subset and Stimulation Strength-Dependent Modulation of T Cell Activation by Kv1.3 Blockers.

PLoS One 2017 20;12(1):e0170102. Epub 2017 Jan 20.

Janssen Research & Development, L.L.C., San Diego, California, United States of America.

Kv1.3 is a voltage-gated potassium channel expressed on T cells that plays an important role in T cell activation. Previous studies have shown that blocking Kv1.3 channels in human T cells during activation results in reduced calcium entry, cytokine production, and proliferation. The aim of the present study was to further explore the effects of Kv1.3 blockers on the response of different human T cell subsets under various stimulation conditions. Our studies show that, unlike the immune suppressor cyclosporine A, the inhibitory effect of Kv1.3 blockers was partial and stimulation strength dependent, with reduced inhibitory efficacy on T cells under strengthened anti-CD3/CD28 stimulations. T cell responses to allergens including house dust mites and ragweed were partially reduced by Kv1.3 blockers. The effect of Kv1.3 inhibition was dependent on T cell subsets, with stronger effects on CCR7- effector memory compared to CCR7+ central memory CD4 T cells. Calcium entry studies also revealed a population of CD4 T cells resistant to Kv1.3 blockade. Activation of CD4 T cells was accompanied with an increase in Kv1.3 currents but Kv1.3 transcripts were found to be reduced, suggesting a posttranscriptional mechanism in the regulation of Kv1.3 activities. In summary, Kv1.3 blockers inhibit T cell activation in a manner that is highly dependent on the T cell identity and stimulation strength, These findings suggest that Kv1.3 blockers inhibit T cells in a unique, conditional manner, further refining our understanding of the therapeutic potential of Kv1.3 blockers.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0170102PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5249144PMC
August 2017

State-Dependent Allosteric Inhibition of the Human SLC13A5 Citrate Transporter by Hydroxysuccinic Acids, PF-06649298 and PF-06761281.

Mol Pharmacol 2016 Dec 17;90(6):766-774. Epub 2016 Oct 17.

Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, LLC., San Diego, California (M.-L.R., M.S., A.D.W.) and Cardiovascular and Metabolism Discovery, Janssen R&D, LLC., Springhouse, Pennsylvania, (B.Z., S.A.H.)

In the liver, citrate is a key metabolic intermediate involved in the regulation of glycolysis and lipid synthesis and reduced expression of the hepatic citrate SLC13A5 transporter has been shown to improve metabolic outcomes in various animal models. Although inhibition of hepatic extracellular citrate uptake through SLC13A5 has been suggested as a potential therapeutic approach for Type-2 diabetes and/or fatty liver disease, so far, only a few SLC13A5 inhibitors have been identified. Moreover, their mechanism of action still remains unclear, potentially limiting their utility for in vivo proof-of-concept studies. In this study, we characterized the pharmacology of the recently identified hydroxysuccinic acid SLC13A5 inhibitors, PF-06649298 and PF-06761281, using a combination of C-citrate uptake, a membrane potential assay and electrophysiology. In contrast to their previously proposed mechanism of action, our data suggest that both PF-06649298 and PF-06761281 are allosteric, state-dependent SLC13A5 inhibitors, with low-affinity substrate activity in the absence of citrate. As allosteric state-dependent modulators, the inhibitory potency of both compounds is highly dependent on the ambient citrate concentration and our detailed mechanism of action studies therefore, may be of value in interpreting the in vivo effects of these compounds.
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http://dx.doi.org/10.1124/mol.116.106575DOI Listing
December 2016

The discovery and preclinical characterization of 6-chloro-N-(2-(4,4-difluoropiperidin-1-yl)-2-(2-(trifluoromethyl)pyrimidin-5-yl)ethyl)quinoline-5-carboxamide based P2X7 antagonists.

Bioorg Med Chem Lett 2016 10 20;26(19):4781-4784. Epub 2016 Aug 20.

Janssen Pharmaceutical Research & Development L.L.C., 3210 Merryfield Row, San Diego, CA 92121, United States.

The synthesis, SAR and preclinical characterization of a series of 6-chloro-N-(2-(4,4-difluoropiperidin-1-yl)-2-(2-(trifluoromethyl)pyrimidin-5-yl)ethyl)quinoline-5-carboxamide based P2X7 antagonists is described herein. The lead compounds are potent inhibitors in Ca(2+) flux and whole blood IL-1β P2X7 release assays at both human and mouse isoforms. Compound 1e showed a robust reduction of IL-1β release in a mouse ex vivo model with a 50mg/kg oral dose. Evaluation of compound 1e in the mouse SNI tactile allodynia, carrageenan-induced paw edema or CIA models resulted in no analgesic or anti-inflammatory effects.
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http://dx.doi.org/10.1016/j.bmcl.2016.08.029DOI Listing
October 2016

Discovery and Characterization of AMPA Receptor Modulators Selective for TARP-γ8.

J Pharmacol Exp Ther 2016 May 17;357(2):394-414. Epub 2016 Mar 17.

Janssen Research and Development, LLC, Neuroscience Therapeutic Area, San Diego, California (M.P.M., N.W., S.R., M.K.A., B.M.S., C.L., B.L., R.M.W., J.A.M., C.D., S.Y., A.D.W., N.I.C., T.W.L.); and Janssen Research and Development, a Division of Janssen Pharmaceutica NV, Neuroscience Therapeutic Area, Beerse, Belgium (L.V.D., T.S.).

Members of the α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid (AMPA) subtype of ionotropic glutamate receptors mediate the majority of fast synaptic transmission within the mammalian brain and spinal cord, representing attractive targets for therapeutic intervention. Here, we describe novel AMPA receptor modulators that require the presence of the accessory protein CACNG8, also known as transmembrane AMPA receptor regulatory protein γ8 (TARP-γ8). Using calcium flux, radioligand binding, and electrophysiological assays of wild-type and mutant forms of TARP-γ8, we demonstrate that these compounds possess a novel mechanism of action consistent with a partial disruption of the interaction between the TARP and the pore-forming subunit of the channel. One of the molecules, 5-[2-chloro-6-(trifluoromethoxy)phenyl]-1,3-dihydrobenzimidazol-2-one (JNJ-55511118), had excellent pharmacokinetic properties and achieved high receptor occupancy following oral administration. This molecule showed strong, dose-dependent inhibition of neurotransmission within the hippocampus, and a strong anticonvulsant effect. At high levels of receptor occupancy in rodent in vivo models, JNJ-55511118 showed a strong reduction in certain bands on electroencephalogram, transient hyperlocomotion, no motor impairment on rotarod, and a mild impairment in learning and memory. JNJ-55511118 is a novel tool for reversible AMPA receptor inhibition, particularly within the hippocampus, with potential therapeutic utility as an anticonvulsant or neuroprotectant. The existence of a molecule with this mechanism of action demonstrates the possibility of pharmacological targeting of accessory proteins, increasing the potential number of druggable targets.
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http://dx.doi.org/10.1124/jpet.115.231712DOI Listing
May 2016

Targeting the ion channel Kv1.3 with scorpion venom peptides engineered for potency, selectivity, and half-life.

J Biol Chem 2014 Aug 17;289(33):22704-22714. Epub 2014 Jun 17.

Janssen Research and Development, LLC, San Diego, California 92121.

Ion channels are an attractive class of drug targets, but progress in developing inhibitors for therapeutic use has been limited largely due to challenges in identifying subtype selective small molecules. Animal venoms provide an alternative source of ion channel modulators, and the venoms of several species, such as scorpions, spiders and snails, are known to be rich sources of ion channel modulating peptides. Importantly, these peptides often bind to hyper-variable extracellular loops, creating the potential for subtype selectivity rarely achieved with small molecules. We have engineered scorpion venom peptides and incorporated them in fusion proteins to generate highly potent and selective Kv1.3 inhibitors with long in vivo half-lives. Kv1.3 has been reported to play a role in human T cell activation, and therefore, these Kv1.3 inhibitor fusion proteins may have potential for the treatment of autoimmune diseases. Our results support an emerging approach to generating subtype selective therapeutic ion channel inhibitors.
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http://dx.doi.org/10.1074/jbc.M114.568642DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132777PMC
August 2014

A disulfide tether stabilizes the block of sodium channels by the conotoxin μO§-GVIIJ.

Proc Natl Acad Sci U S A 2014 Feb 4;111(7):2758-63. Epub 2014 Feb 4.

Department of Biology and Department of Medicinal Chemistry, L. S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, UT 84112.

A cone snail venom peptide, μO§-conotoxin GVIIJ from Conus geographus, has a unique posttranslational modification, S-cysteinylated cysteine, which makes possible formation of a covalent tether of peptide to its target Na channels at a distinct ligand-binding site. μO§-conotoxin GVIIJ is a 35-aa peptide, with 7 cysteine residues; six of the cysteines form 3 disulfide cross-links, and one (Cys24) is S-cysteinylated. Due to limited availability of native GVIIJ, we primarily used a synthetic analog whose Cys24 was S-glutathionylated (abbreviated GVIIJSSG). The peptide-channel complex is stabilized by a disulfide tether between Cys24 of the peptide and Cys910 of rat (r) NaV1.2. A mutant channel of rNaV1.2 lacking a cysteine near the pore loop of domain II (C910L), was >10(3)-fold less sensitive to GVIIJSSG than was wild-type rNaV1.2. In contrast, although rNaV1.5 was >10(4)-fold less sensitive to GVIIJSSG than NaV1.2, an rNaV1.5 mutant with a cysteine in the homologous location, rNaV1.5[L869C], was >10(3)-fold more sensitive than wild-type rNaV1.5. The susceptibility of rNaV1.2 to GVIIJSSG was significantly altered by treating the channels with thiol-oxidizing or disulfide-reducing agents. Furthermore, coexpression of rNaVβ2 or rNaVβ4, but not that of rNaVβ1 or rNaVβ3, protected rNaV1.1 to -1.7 (excluding NaV1.5) against block by GVIIJSSG. Thus, GVIIJ-related peptides may serve as probes for both the redox state of extracellular cysteines and for assessing which NaVβ- and NaVα-subunits are present in native neurons.
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http://dx.doi.org/10.1073/pnas.1324189111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932919PMC
February 2014

Overview of Electrophysiological Techniques.

Authors:
Alan D Wickenden

Curr Protoc Pharmacol 2014 Mar 3;64:11.1.1-17. Epub 2014 Mar 3.

Janssen R&D, San Diego, California.

This unit provides an overview of the principal electrophysiological techniques commonly used for the study of ionic currents and the ion channels that mediate them. These techniques include electroencephalograms (EEGs), electrocardiograms (ECGs), single- and multiunit extracellular recording, multielectrode arrays, transepithelial recording, impedance measurements, and current-clamp, voltage-clamp, patch-clamp, and lipid bilayer recording. The unit also discusses recent advances in high-throughput, automated electrophysiological techniques for drug discovery and the use of stem cells as a tissue source.
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http://dx.doi.org/10.1002/0471141755.ph1101s64DOI Listing
March 2014

Pharmacological characterization of a novel centrally permeable P2X7 receptor antagonist: JNJ-47965567.

Br J Pharmacol 2013 Oct;170(3):624-40

Neuroscience Therapeutic Area, Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, CA, USA.

Background And Purpose: An increasing body of evidence suggests that the purinergic receptor P2X, ligand-gated ion channel, 7 (P2X7) in the CNS may play a key role in neuropsychiatry, neurodegeneration and chronic pain. In this study, we characterized JNJ-47965567, a centrally permeable, high-affinity, selective P2X7 antagonist.

Experimental Approach: We have used a combination of in vitro assays (calcium flux, radioligand binding, electrophysiology, IL-1β release) in both recombinant and native systems. Target engagement of JNJ-47965567 was demonstrated by ex vivo receptor binding autoradiography and in vivo blockade of Bz-ATP induced IL-1β release in the rat brain. Finally, the efficacy of JNJ-47965567 was tested in standard models of depression, mania and neuropathic pain.

Key Results: JNJ-47965567 is potent high affinity (pKi 7.9 ± 0.07), selective human P2X7 antagonist, with no significant observed speciation. In native systems, the potency of the compound to attenuate IL-1β release was 6.7 ± 0.07 (human blood), 7.5 ± 0.07 (human monocytes) and 7.1 ± 0.1 (rat microglia). JNJ-47965567 exhibited target engagement in rat brain, with a brain EC50 of 78 ± 19 ng·mL(-1) (P2X7 receptor autoradiography) and functional block of Bz-ATP induced IL-1β release. JNJ-47965567 (30 mg·kg(-1) ) attenuated amphetamine-induced hyperactivity and exhibited modest, yet significant efficacy in the rat model of neuropathic pain. No efficacy was observed in forced swim test.

Conclusion And Implications: JNJ-47965567 is centrally permeable, high affinity P2X7 antagonist that can be used to probe the role of central P2X7 in rodent models of CNS pathophysiology.
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http://dx.doi.org/10.1111/bph.12314DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3792000PMC
October 2013

Analysis of the structural and molecular basis of voltage-sensitive sodium channel inhibition by the spider toxin huwentoxin-IV (μ-TRTX-Hh2a).

J Biol Chem 2013 Aug 12;288(31):22707-20. Epub 2013 Jun 12.

Department of Neuroscience Discovery, Janssen Research & Development, LLC, San Diego, California 92121, USA.

Voltage-gated sodium channels (VGSCs) are essential to the normal function of the vertebrate nervous system. Aberrant function of VGSCs underlies a variety of disorders, including epilepsy, arrhythmia, and pain. A large number of animal toxins target these ion channels and may have significant therapeutic potential. Most of these toxins, however, have not been characterized in detail. Here, by combining patch clamp electrophysiology and radioligand binding studies with peptide mutagenesis, NMR structure determination, and molecular modeling, we have revealed key molecular determinants of the interaction between the tarantula toxin huwentoxin-IV and two VGSC isoforms, Nav1.7 and Nav1.2. Nine huwentoxin-IV residues (F6A, P11A, D14A, L22A, S25A, W30A, K32A, Y33A, and I35A) were important for block of Nav1.7 and Nav1.2. Importantly, molecular dynamics simulations and NMR studies indicated that folding was normal for several key mutants, suggesting that these amino acids probably make specific interactions with sodium channel residues. Additionally, we identified several amino acids (F6A, K18A, R26A, and K27A) that are involved in isoform-specific VGSC interactions. Our structural and functional data were used to model the docking of huwentoxin-IV into the domain II voltage sensor of Nav1.7. The model predicts that a hydrophobic patch composed of Trp-30 and Phe-6, along with the basic Lys-32 residue, docks into a groove formed by the Nav1.7 S1-S2 and S3-S4 loops. These results provide new insight into the structural and molecular basis of sodium channel block by huwentoxin-IV and may provide a basis for the rational design of toxin-based peptides with improved VGSC potency and/or selectivity.
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http://dx.doi.org/10.1074/jbc.M113.461392DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3829356PMC
August 2013

Synthesis and Pharmacological Characterization of Two Novel, Brain Penetrating P2X7 Antagonists.

ACS Med Chem Lett 2013 Apr 12;4(4):419-22. Epub 2013 Mar 12.

Janssen Research and Development, LLC , 3210 Merryfield Row, San Diego, California 92121-1126, United States.

The synthesis and preclinical characterization of two novel, brain penetrating P2X7 compounds will be described. Both compounds are shown to be high potency P2X7 antagonists in human, rat, and mouse cell lines and both were shown to have high brain concentrations and robust receptor occupancy in rat. Compound 7 is of particular interest as a probe compound for the preclinical assessment of P2X7 blockade in animal models of neuro-inflammation.
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http://dx.doi.org/10.1021/ml400040vDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027403PMC
April 2013

Discovery of a novel series of selective HCN1 blockers.

Bioorg Med Chem Lett 2011 Sep 23;21(18):5197-201. Epub 2011 Jul 23.

Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, United States.

The discovery of a series of novel, potent, and selective blockers of the cyclic nucleotide-modulated channel HCN1 is disclosed. Here we report an SAR study around a series of selective blockers of the HCN1 channel. Utilization of a high-throughput VIPR assay led to the identification of a novel series of 2,2-disubstituted indane derivatives, which had moderate selectivity and potency at HCN1. Optimization of this hit led to the identification of the potent, 1,1-disubstituted cyclohexane HCN1 blocker, 2-ethoxy-N-((1-(4-isopropylpiperazin-1-yl)cyclohexyl)methyl)benzamide. The work leading to the discovery of this compound is described herein.
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http://dx.doi.org/10.1016/j.bmcl.2011.07.051DOI Listing
September 2011

N-Pyridyl and Pyrimidine Benzamides as KCNQ2/Q3 Potassium Channel Openers for the Treatment of Epilepsy.

ACS Med Chem Lett 2011 Jun 31;2(6):481-4. Epub 2011 Mar 31.

Departments of Chemistry, Pharmacology, and Biology, Icagen Inc. , 4222 Emperor Boulevard, Durham, North Carolina 27702, United States.

A series of N-pyridyl benzamide KCNQ2/Q3 potassium channel openers were identified and found to be active in animal models of epilepsy and pain. The best compound 12 [ICA-027243, N-(6-chloro-pyridin-3-yl)-3,4-difluoro-benzamide] has an EC50 of 0.38 μM and is selective for KCNQ2/Q3 channels. This compound was active in several rodent models of epilepsy and pain but upon repeated dosing had a number of unacceptable toxicities that prevented further development. On the basis of the structure-activity relationships developed around 12, a second compound, 51, [N-(2-chloro-pyrimidin-5-yl)-3,4-difluoro-benzamide, ICA-069673], was prepared and advanced into a phase 1 clinical study. Herein, we describe the structure-activity relationships that led to the identification of compound 12 and to the corresponding pyrimidine 51.
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http://dx.doi.org/10.1021/ml200053xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018159PMC
June 2011

Characterization of 2-(2,6-dichloro-benzyl)-thiazolo[5,4-d]pyrimidin-7-yl]-(4-trifluoromethyl-phenyl)-amine (JNJ-39729209) as a novel TRPV1 antagonist.

Eur J Pharmacol 2011 Aug 10;663(1-3):40-50. Epub 2011 May 10.

Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA.

As an integrator of multiple nociceptive and/or inflammatory stimuli, TRPV1 is an attractive therapeutic target for the treatment of various painful disorders. Several TRPV1 antagonists have been advanced into clinical trials and the initial observations suggest that TRPV1 antagonism may be associated with mild hyperthermia and thermal insensitivity in man. However, no clinical efficacy studies have been described to date, making an assessment of risk:benefit impossible. Furthermore, it is not clear whether these early observations are representative of all TRPV1 antagonists and whether additional clinical studies with novel TRPV1 antagonists are required in order to understand optimal compound characteristics. In the present study we describe 2-(2,6-dichloro-benzyl)-thiazolo[5,4-d]pyrimidin-7-yl]-(4-trifluoromethyl-phenyl)-amine (JNJ-39729309) as a novel, TRPV1 antagonist. JNJ-39729209 displaced tritiated resiniferotoxin binding to TRPV1 and prevented TRPV1 activation by capsaicin, protons and heat. In-vivo, JNJ-39729209 blocked capsaicin-induced hypotension, induced a mild hyperthermia and inhibited capsaicin-induced hypothermia in a dose dependent manner. JNJ-39729209 showed significant efficacy against carrageenan- and CFA-evoked thermal hyperalgesia and exhibited significant anti-tussive activity in a guinea-pig model of capsaicin-induced cough. In pharmacokinetic studies, JNJ-39729209 was found to have low clearance, a moderate volume of distribution, good oral bioavailability and was brain penetrant. On the basis of these findings, JNJ-39729209 represents a structurally novel TRPV1 antagonist with potential for clinical development. The advancement of JNJ-39729209 into human clinical trials could be useful in further understanding the analgesic potential of TRPV1 antagonists.
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http://dx.doi.org/10.1016/j.ejphar.2011.05.001DOI Listing
August 2011

The physiology, pharmacology and future of P2X7 as an analgesic drug target: hype or promise?

Curr Pharm Biotechnol 2011 Oct;12(10):1698-706

Neuroscience, Johnson & Johnson Pharmaceutical Research & Development LLC., San Diego, CA 92121, USA.

P2X7 is an ATP-gated non-selective cation channel expressed primarily on cells of hematopoietic origin, such as macrophages and microglia. Since the initial cloning of this channel, enormous progress has been made in the understanding of the physiology, pharmacology and therapeutic utility of P2X7. This article attempts to review the biology of P2X7 with a focus on the complex pharmacology of this channel. Finally, the authors discuss the role of P2X7 as an analgesic drug target and raise some of the challenges and issues that face the P2X7 research community.
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http://dx.doi.org/10.2174/138920111798357429DOI Listing
October 2011

Recent advances in the biology and medicinal chemistry of TRPA1.

Future Med Chem 2010 May;2(5):843-58

Johnson & Johnson Pharmaceutical Research & Development, LLC, San Diego, CA 92121, USA.

The transient receptor potential cation channel, subfamily A, member 1 (TRPA1) is a nonselective cation channel that is highly expressed in small-diameter sensory neurons, where it functions as a polymodal receptor, responsible for detecting potentially harmful chemicals, mechanical forces and temperatures. TRPA1 is also activated and/or sensitized by multiple endogenous inflammatory mediators. As such, TRPA1 likely mediates the pain and neurogenic inflammation caused by exposure to reactive chemicals. In addition, it is also possible that this channel may mediate some of the symptoms of chronic inflammatory conditions such as asthma. We review recent advances in the biology of TRPA1 and summarize the evidence for TRPA1 as a therapeutic drug target. In addition, we provide an update on TRPA1 medicinal chemistry and the progress in the search for novel TRPA1 antagonists.
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http://dx.doi.org/10.4155/fmc.10.29DOI Listing
May 2010

Discovery and synthesis of 6,7,8,9-tetrahydro-5H-pyrimido-[4,5-d]azepines as novel TRPV1 antagonists.

Bioorg Med Chem Lett 2010 Dec 17;20(23):7137-41. Epub 2010 Sep 17.

Johnson & Johnson Pharmaceutical Research and Development LLC, San Diego, CA 92121, USA.

Utilization of a tetrahydro-pyrimdoazepine core as a bioisosteric replacement for a piperazine-urea resulted in the discovery a novel series of potent antagonists of TRPV1. The tetrahydro-pyrimdoazepines have been identified as having good in vitro and in vivo potency and acceptable physical properties.
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http://dx.doi.org/10.1016/j.bmcl.2010.09.023DOI Listing
December 2010

1,2-diamino-ethane-substituted-6,7,8,9-tetrahydro-5H-pyrimido[4,5-d]azepines as TRPV1 antagonists with improved properties.

Bioorg Med Chem Lett 2010 Dec 7;20(23):7142-6. Epub 2010 Sep 7.

Johnson & Johnson Pharmaceutical Research and Development LLC, San Diego, CA 92121, USA.

Based upon a previously reported lead compound 1, a series of 1,2-diamino-ethane-substituted-6,7,8,9-tetrahydro-5H-pyrimido[4,5-d]azepines were synthesized and evaluated for improved physiochemical and pharmacokinetic properties while maintaining TRPV1 antagonist activity. Structure-activity relationship studies directed toward improving the aqueous solubility (pH 2 and fasted-state simulated intestinal fluid (SIF)) and rat pharmacokinetics led to the discovery of compound 13. Aqueous solubility of compound 13 (pH 2 ≥237 μg/mL and SIF=11 μg/mL) was significantly improved over compound 1 (pH 2=5 μg/mL and SIF=0.5 μg/mL). In addition, compound 13 afforded improved rat pharmacokinetics (CL=0.7 L/kg/h) compared to compound 1 (CL=3.1 L/kg/h). Compound 13 was orally bioavailable and afforded a significant reversal of carrageenan-induced thermal hyperalgesia at 5 and 30 mg/kg in rats.
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http://dx.doi.org/10.1016/j.bmcl.2010.09.006DOI Listing
December 2010

Novel KCNQ2/Q3 agonists as potential therapeutics for epilepsy and neuropathic pain.

J Med Chem 2010 Jan;53(2):887-96

Icagen, Inc., Suite 390, 4222 Emperor Boulevard, Durham, North Carolina 27703, USA.

Current drugs for the treatment of seizure disorders, although effective in many patients, still suffer from a number of failures and are not effective in some forms of resistant epilepsies. Historically, many of these drugs have multiple mechanisms of action including calcium and sodium channel blockade as well as GABAergic activity and thus a number of associated side effects. Modulation of the M-current through opening of KCNQ channels has been proposed as a way to attenuate neuroexcitability and have a therapeutic benefit for the treatment of seizure disorders. Therefore, as part of our program to identify new treatments for epilepsy, we set out to identify agonists of KCNQ channels. High throughput screening of our corporate collection led to the identification of 1, adamantane-1-carboxylic acid (3-methyl-3H-benzothiazol-2-ylidine) hydrazide, a potent KCNQ2/Q3 agonist. Herein, we describe the syntheses and structure-activity relationships of analogues of 1 as well as their in vivo activity in animal models of epilepsy and neuropathic pain.
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http://dx.doi.org/10.1021/jm901497bDOI Listing
January 2010

Sodium channel blockers for the treatment of neuropathic pain.

Neurotherapeutics 2009 Oct;6(4):663-78

Pain & Related Disorders Team, Johnson & Johnson Pharmaceutical Research & Development, LLC, San Diego, California 92121, USA.

Drugs that block voltage-gated sodium channels are efficacious in the management of neuropathic pain. Accordingly, this class of ion channels has been a major focus of analgesic research both in academia and in the pharmaceutical/biotechnology industry. In this article, we review the history of the use of sodium channel blockers, describe the current status of sodium channel drug discovery, highlight the challenges and hurdles to attain sodium channel subtype selectivity, and review the potential usefulness of selective sodium channel blockers in neuropathic pain.
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http://dx.doi.org/10.1016/j.nurt.2009.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5084288PMC
October 2009

The KCNQ2/3 selective channel opener ICA-27243 binds to a novel voltage-sensor domain site.

Neurosci Lett 2009 Nov 3;465(2):138-42. Epub 2009 Sep 3.

Icagen, 4222 Emperor Boulevard, Suite 460, Durham, NC 27703, United States.

The mammalian KCNQ (Kv7) gene family is composed of five members (KCNQ1-5). KCNQ2, Q4 and Q5 (KCNQ2-5) channels co-express with KCNQ3 to form heterotetrameric voltage-gated K(+) (KCNQ2-5/3) channels that underlie the endogenous M-current and regulate neuronal excitability in CNS and PNS neurons. Openers of one or a mixture of these channels may be an attractive therapeutic agent for epilepsy and pain. Non-selective KCNQ2-5/3 activators have shown efficacy in pre-clinical and clinical studies. However, more selective pharmacological profiles, including greater KCNQ sub-type-selective activation, could provide efficacy with fewer side effects. One such compound, ICA-27243, sub-type selectively enhances the activation of KCNQ2/3 channels and also exhibits efficacy in pre-clinical anticonvulsant models; Roeloffs et al. (2008) [15]; Wickenden et al. (2008) [27]. The binding site of non-selective KCNQ2-5/3 openers maps to the S5-S6 pore domain and is altered by mutation of a tryptophan residue (Trp236 in KCNQ2, Trp265 in KCNQ3) conserved among KCNQ2-5 channels; Schenzer et al. (2005) [19]; Wuttke et al. (2005) [30]. Here we report that the activity of the KCNQ2/3 selective opener ICA-27243 is not affected by these Trp mutations and does not map to the S5-S6 domain. Rather, the selective activity of ICA-27243 is determined by a novel site within the S1-S4 voltage-sensor domain (VSD) of KCNQ channels. The sub-type-selective activity of ICA-27243 may arise from greater sequence diversity of KCNQ family members within the ICA-27243 binding pocket, allowing for more selective small molecule-protein interactions.
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http://dx.doi.org/10.1016/j.neulet.2009.08.071DOI Listing
November 2009

Aryl sulfonamido tetralin inhibitors of the Kv1.5 ion channel.

Bioorg Med Chem Lett 2009 Jun 8;19(11):3063-6. Epub 2009 Apr 8.

Icagen Inc, NC 27709, United States.

Aryl sulfonamido tetralins based on lead compound 2a were synthesized and evaluated for Kv1.5 inhibitory activity. Several compounds having IC(50) values less then 0.1 microM were identified. Kv1.5 inhibitors have the potential to be atrium-selective agents for the treatment of atrial fibrillation.
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http://dx.doi.org/10.1016/j.bmcl.2009.04.002DOI Listing
June 2009

Intracellular zinc irritates TRPA1.

Nat Chem Biol 2009 Mar;5(3):141-2

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http://dx.doi.org/10.1038/nchembio0309-141DOI Listing
March 2009

HCN channels as targets for drug discovery.

Comb Chem High Throughput Screen 2009 Jan;12(1):64-72

Johnson & Johnson Pharmaceutical Research and Development, L.L.C., San Diego, CA 92121, USA.

Hyperpolarization- and Cyclic Nucleotide-gated (HCN) channels are a family of six transmembrane domain, single pore-loop, hyperpolarization activated, non-selective cation channels. The HCN family consists of four members (HCN1-4). HCN channels represent the molecular correlates of I(h) (also known as 'funny' I(f) and 'queer' I(q)), a hyperpolarization-activated current best known for its role in controlling heart rate and in the regulation of neuronal resting membrane potential and excitability. A significant body of molecular and pharmacological evidence is now emerging to support a role for these channels in the function of sensory neurons and pain sensation, particularly pain associated with nerve or tissue injury. As such, HCN channels may represent valid targets for novel analgesic agents. This evidence will be reviewed in this article. We will then summarize our efforts to develop and validate methods for screening for novel HCN channel blockers.
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http://dx.doi.org/10.2174/138620709787048028DOI Listing
January 2009

Identification and synthesis of 2,7-diamino-thiazolo[5,4-d]pyrimidine derivatives as TRPV1 antagonists.

Bioorg Med Chem Lett 2009 Jan 13;19(1):40-6. Epub 2008 Nov 13.

Johnson & Johnson Pharmaceutical Research and Development LLC, San Diego, CA 92121, USA.

We have identified and synthesized a series of 2,7-diamino-thiazolo[5,4-d]pyrimidines as TRPV1 antagonists. An exploration of the structure-activity relationships at the 2-, 5-, and 7-positions of the thiazolo[5,4-d]pyrimidine led to the identification of several potent TRPV1 antagonists, including 3, 29, 51, and 57. Compound 3 was orally bioavailable and afforded a significant reversal of carrageenan-induced thermal hyperalgesia with an ED(50)=0.5mg/kg in rats.
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http://dx.doi.org/10.1016/j.bmcl.2008.11.024DOI Listing
January 2009