Kidney CLC-K chloride channels inhibitors

Liantonio, Antonella; Imbrici, Paola; Camerino, Giulia Maria; Fracchiolla, Giuseppe; Carbonara, Giuseppe; Giannico, Donato; Gradogna, Antonella; Mangiatordi, Giuseppe Felice; Nicolotti, Orazio; Tricarico, Domenico; Pusch, Michael; Camerino, Diana Conte

doi:10.1097/hjh.0000000000000876

Cited by 19 publications

(14 citation statements)

References 58 publications

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“…Given that the stria vascularis is not protected from systemic circulation by the blood-cochlear-barrier (Jahnke, 1975) this implies that great care has to be taken when considering CLC-K blockers as potential diuretic drugs in the treatment of hypertension (Imbrici et al, 2014; Liantonio et al, 2016). On the other hand, this peculiarity makes the systemic application of activators of CLC-K/barttin (Zifarelli et al, 2010) or drugs enhancing folding and trafficking of barttin (Nomura et al, 2013) for treating sensorineural deafness possible.…”

Section: Discussionmentioning

confidence: 99%

Reduced Membrane Insertion of CLC-K by V33L Barttin Results in Loss of Hearing, but Leaves Kidney Function Intact

et al. 2017

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In the mammalian ear, transduction of sound stimuli is initiated by K+ entry through mechano-sensitive channels into inner hair cells. K+ entry is driven by a positive endocochlear potential that is maintained by the marginal cell layer of the stria vascularis. This process requires basolateral K+ import by NKCC1 Na+−2Cl−−K+ co-transporters as well as Cl− efflux through ClC-Ka/barttin or ClC-Kb/barttin channels. Multiple mutations in the gene encoding the obligatory CLC-K subunit barttin, BSND, have been identified in patients with Bartter syndrome type IV. These mutations reduce the endocochlear potential and cause deafness. As CLC-K/barttin channels are also expressed in the kidney, patients with Bartter syndrome IV typically also suffer from salt-wasting hyperuria and electrolyte imbalances. However, there was a single report on a BSND mutation that resulted only in deafness, but not kidney disease. We herein studied the functional consequences of another recently discovered BSND mutation that predicts exchange of valine at position 33 by leucine. We combined whole-cell patch clamp, confocal microscopy and protein biochemistry to analyze how V33L affects distinct functions of barttin. We found that V33L reduced membrane insertion of CLC-K/barttin complexes without altering unitary CLC-K channel function. Our findings support the hypothesis of a common pathophysiology for the selective loss of hearing due to an attenuation of the total chloride conductance in the stria vascularis while providing enough residual function to maintain normal kidney function.

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Section: Discussionmentioning

confidence: 99%

Reduced Membrane Insertion of CLC-K by V33L Barttin Results in Loss of Hearing, but Leaves Kidney Function Intact

et al. 2017

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“…Based on the kinetics and reversibility of inhibition (Extended Data Figures 3, 4), we reasoned that AK-42 is likely binding to the extracellular side of channel pore. Docking of AK-42 to the extracellular side of the CLC-2 model preferentially places this ligand near the outer vestibule of the ionpermeation pathway, in a similar site to that targeted by anionic inhibitors in CLC-Ka 35,36 . Notably, we found that AK-42 does not dock to the cryo-EM structure of CLC-1 (6COY) 45 , in line with our functional studies on selectivity ( Figure 2C).…”

Section: Ak-42 Selectivity Specificity and Binding Sitementioning

confidence: 99%

“…Commercially available Cl --channel inhibitors 29 lack potency, with mid-µM to mM concentrations required to achieve inhibition of Clcurrent 9,30-32 .These molecules also generally lack selectivity against the different types of Clchannels, which strictly limits the usefulness of these compounds for cellular and organismal studies. For the CLC channels, the most potent and selective small-molecule inhibitors are those targeting CLC-Ka, one of two CLC homologs expressed in the kidney [33][34][35][36] . For CLC-2, the only reported small-molecule (non-peptide) inhibitors require application of high concentrations (~1 mM) 9,10,24,37 .…”

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confidence: 99%

Development and validation of a potent and specific inhibitor for the CLC-2 chloride channel

Bois

Maduke

Huguenard

2020

Preprint

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CLC-2 is a voltage-gated chloride channel expressed ubiquitously in mammalian tissue. Studies to define how CLC-2 contributes to normal and pathophysiological brain function have produced controversial results, in part due to the absence of precise pharmacological tools for modulating CLC-2 function. Herein, we describe the development and optimization of a new small-molecule inhibitor of CLC-2, AK-42, that exhibits unprecedented potency and specificity. Computational docking, validated by mutagenesis and kinetic studies, indicates that AK-42 binds to an extracellular vestibule above the channel pore. AK-42 acutely and specifically inhibits CLC-2 currents in CA1 hippocampal pyramidal neurons. Use of AK-42 in an established thalamic-slice model for studying epilepsy suggests a role for CLC-2 in modulating electrical excitability and implicates CLC-2 as a possible anti-epileptic target. These results establish AK-42 as a powerful new tool for investigating CLC-2 physiology in the central nervous system.The CLC-2 channel belongs to the "CLC" family of Cl --selective ion channels and transporters, of which there are nine mammalian homologs 9 . CLC-2 is activated by hyperpolarization of the plasma membrane and is expressed in nearly every tissue-type, including brain, heart, intestines, and lungs 10 . Interest in CLC-2 physiology in the CNS was sparked by CLC-2 knockout mouse phenotypes, which display severe deficiencies, including retinal degeneration/blindness and vacuolization of myelin in brain tissue [11][12][13] . In addition, human patient data suggest a link between CLC-2 malfunction and certain forms of generalized epilepsies [14][15][16][17][18][19][20][21] . Although a causative role for CLC-2 underlying genetic disease remains controversial 22,23 , the available research, together with the widespread expression of CLC-2 in the CNS 10,11,24-28 , motivate further examination of this channel.Understanding CLC-2 physiology has proven difficult in the absence of selective and specific chemical reagents for labeling and modulating the activity of this ion channel. Commercially available Cl --channel inhibitors 29 lack potency, with mid-µM to mM concentrations required to achieve inhibition of Clcurrent 9,30-32 .These molecules also generally lack selectivity against the different types of Clchannels, which strictly limits the usefulness of these compounds for cellular and organismal studies. For the CLC channels, the most potent and selective small-molecule inhibitors are those targeting CLC-Ka, one of two CLC homologs expressed in the kidney [33][34][35][36] . For CLC-2, the only reported small-molecule (non-peptide) inhibitors require application of high concentrations (~1 mM) 9,10,24,37 . CLC-2 is also inhibited by low µM concentrations of the divalent cations, Cd 2+ and Zn 2+ 38,39 ; however, these ions are toxic and lack subtype specificity. A peptide toxin, GaTx2, has been reported to selectively inhibit CLC-2 at concentrations of ~20 pM 40 ; however, current inhibition saturates at ~50% with the applicat...

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“…However, due to expression of ClC-K/barttin channels in both the kidney and inner ear, it will be difficult to develop specific drugs without undesirable side effects. Recently, while testing new benzofuran derivatives designed to block ClC-K function, Liantonio et al (2016) described the most potent and selective ClC-K blocker discovered to date (SRA-36). This compound is able to inhibit not only wild-type channels, but also the Cl - currents of polymorphic ClC-K channels associated with hypertension (Liantonio et al, 2016).…”

Section: Mammalian Clcs and Human Disordersmentioning

confidence: 99%

“…Recently, while testing new benzofuran derivatives designed to block ClC-K function, Liantonio et al (2016) described the most potent and selective ClC-K blocker discovered to date (SRA-36). This compound is able to inhibit not only wild-type channels, but also the Cl - currents of polymorphic ClC-K channels associated with hypertension (Liantonio et al, 2016). Although several studies have made significant progress on the identification of compounds modulating ClC-K channel function (Liantonio et al, 2004, 2006, 2016; Picollo et al, 2004), there are not yet therapeutic drugs available.…”

Section: Mammalian Clcs and Human Disordersmentioning

confidence: 99%

ClC Channels and Transporters: Structure, Physiological Functions, and Implications in Human Chloride Channelopathies

2017

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The discovery of ClC proteins at the beginning of the 1990s was important for the development of the Cl- transport research field. ClCs form a large family of proteins that mediate voltage-dependent transport of Cl- ions across cell membranes. They are expressed in both plasma and intracellular membranes of cells from almost all living organisms. ClC proteins form transmembrane dimers, in which each monomer displays independent ion conductance. Eukaryotic members also possess a large cytoplasmic domain containing two CBS domains, which are involved in transport modulation. ClC proteins function as either Cl- channels or Cl-/H+ exchangers, although all ClC proteins share the same basic architecture. ClC channels have two gating mechanisms: a relatively well-studied fast gating mechanism, and a slow gating mechanism, which is poorly defined. ClCs are involved in a wide range of physiological processes, including regulation of resting membrane potential in skeletal muscle, facilitation of transepithelial Cl- reabsorption in kidneys, and control of pH and Cl- concentration in intracellular compartments through coupled Cl-/H+ exchange mechanisms. Several inherited diseases result from C1C gene mutations, including myotonia congenita, Bartter’s syndrome (types 3 and 4), Dent’s disease, osteopetrosis, retinal degeneration, and lysosomal storage diseases. This review summarizes general features, known or suspected, of ClC structure, gating and physiological functions. We also discuss biophysical properties of mammalian ClCs that are directly involved in the pathophysiology of several human inherited disorders, or that induce interesting phenotypes in animal models.

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Kidney CLC-K chloride channels inhibitors

Abstract: The SRA-36 molecule represents a new potential therapeutic option for hypertension.

Cited by 19 publications

References 58 publications

Reduced Membrane Insertion of CLC-K by V33L Barttin Results in Loss of Hearing, but Leaves Kidney Function Intact

Reduced Membrane Insertion of CLC-K by V33L Barttin Results in Loss of Hearing, but Leaves Kidney Function Intact

Development and validation of a potent and specific inhibitor for the CLC-2 chloride channel

ClC Channels and Transporters: Structure, Physiological Functions, and Implications in Human Chloride Channelopathies

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