title: Potent KCNQ2/3-specific channel activator suppresses in vivo epileptic activity and prevents the development of tinnitus.
abstract: Voltage-gated Kv7 (KCNQ) channels are voltage-dependent potassium channels that are activated at resting membrane potentials and therefore provide a powerful brake on neuronal excitability. Genetic or experience-dependent reduction of KCNQ2/3 channel activity is linked with disorders that are characterized by neuronal hyperexcitability, such as epilepsy and tinnitus. Retigabine, a small molecule that activates KCNQ2-5 channels by shifting their voltage-dependent opening to more negative voltages, is an US Food and Drug Administration (FDA) approved anti-epileptic drug. However, recently identified side effects have limited its clinical use. As a result, the development of improved KCNQ2/3 channel activators is crucial for the treatment of hyperexcitability-related disorders. By incorporating a fluorine substituent in the 3-position of the tri-aminophenyl ring of retigabine, we synthesized a small-molecule activator (SF0034) with novel properties. Heterologous expression of KCNQ2/3 channels in HEK293T cells showed that SF0034 was five times more potent than retigabine at shifting the voltage dependence of KCNQ2/3 channels to more negative voltages. Moreover, unlike retigabine, SF0034 did not shift the voltage dependence of either KCNQ4 or KCNQ5 homomeric channels. Conditional deletion of Kcnq2 from cerebral cortical pyramidal neurons showed that SF0034 requires the expression of KCNQ2/3 channels for reducing the excitability of CA1 hippocampal neurons. Behavioral studies demonstrated that SF0034 was a more potent and less toxic anticonvulsant than retigabine in rodents. Furthermore, SF0034 prevented the development of tinnitus in mice. We propose that SF0034 provides, not only a powerful tool for investigating ion channel properties, but, most importantly, it provides a clinical candidate for treating epilepsy and preventing tinnitus.
authors.affiliation: Department of Otolaryngology and Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.
authors.forename: Bopanna I
authors.initials: BI
authors.lastname: Kalappa
authors.affiliation: Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269, and.
authors.forename: Heun
authors.initials: H
authors.lastname: Soh
authors.affiliation: Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269, and.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Duignan
authors.affiliation: SciFluor Life Sciences, Inc., Cambridge, Massachusetts 02139.
authors.forename: Takeru
authors.initials: T
authors.lastname: Furuya
authors.affiliation: SciFluor Life Sciences, Inc., Cambridge, Massachusetts 02139.
authors.forename: Scott
authors.initials: S
authors.lastname: Edwards
authors.affiliation: Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269, and thanos@pitt.edu anastasios.tzingounis@uconn.edu.
authors.forename: Anastasios V
authors.initials: AV
authors.lastname: Tzingounis
authors.affiliation: Department of Otolaryngology and Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, thanos@pitt.edu anastasios.tzingounis@uconn.edu.
authors.forename: Thanos
authors.initials: T
authors.lastname: Tzounopoulos
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000927:Anticonvulsants / Q000737:chemistry / Q000627:therapeutic use*; D002219:Carbamates / Q000737:chemistry / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004827:Epilepsy / Q000188:drug therapy* / Q000209:etiology / Q000235:genetics; D016057:Evoked Potentials, Auditory, Brain Stem / Q000235:genetics; D005260:Female; D057809:HEK293 Cells; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D051656:KCNQ Potassium Channels / Q000235:genetics; D051658:KCNQ2 Potassium Channel / Q000819:agonists* / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008813:Mice, Inbred ICR; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D010655:Phenylenediamines / Q000737:chemistry / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014012:Tinnitus / Q000209:etiology / Q000517:prevention & control*; D014157:Transcription Factors / Q000235:genetics; D000099260:Empty Spiracles Homeobox Proteins
chemical_list: D000927:Anticonvulsants; D002219:Carbamates; D018398:Homeodomain Proteins; D051656:KCNQ Potassium Channels; D051658:KCNQ2 Potassium Channel; D010655:Phenylenediamines; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins; C117367:KCNQ4 protein, human; C412231:KCNQ5 protein, human; C101866:ezogabine
keywords: KCNQ channels; epilepsy; tinnitus