Review Article | Published:

Chloride channels as drug targets

Nature Reviews Drug Discovery volume 8, pages 153171 (2009) | Download Citation

Subjects

Abstract

Chloride channels represent a relatively under-explored target class for drug discovery as elucidation of their identity and physiological roles has lagged behind that of many other drug targets. Chloride channels are involved in a wide range of biological functions, including epithelial fluid secretion, cell-volume regulation, neuroexcitation, smooth-muscle contraction and acidification of intracellular organelles. Mutations in several chloride channels cause human diseases, including cystic fibrosis, macular degeneration, myotonia, kidney stones, renal salt wasting and hyperekplexia. Chloride-channel modulators have potential applications in the treatment of some of these disorders, as well as in secretory diarrhoeas, polycystic kidney disease, osteoporosis and hypertension. Modulators of GABAA (γ-aminobutyric acid A) receptor chloride channels are in clinical use and several small-molecule chloride-channel modulators are in preclinical development and clinical trials. Here, we discuss the broad opportunities that remain in chloride-channel-based drug discovery.

Key points

  • There are five main classes of chloride channels: cystic fibrosis transmembrane conductance regulator (CFTR), calcium-activated, voltage-dependent, ligand-gated and volume-sensitive. Chloride channels are attractive targets for drug development for a wide range of human disorders.

  • Fluorescence and electrophysiological high-throughput assays are now available for the discovery of chloride-channel modulators. Cell-based assays utilizing halide-sensing yellow fluorescent proteins are particularly useful for rapid, cost-effective screening.

  • Mutations in CFTR chloride channels cause the hereditary disease cystic fibrosis, and overactivation of CFTR causes secretory diarrhoeas. Small-molecule inhibitors of normal CFTR are in development, as are potentiators and correctors of cystic fibrosis-causing mutant CFTRs.

  • Calcium-activated chloride channels are involved in a wide range of physiological functions, including transepithelial fluid secretion, oocyte fertilization, olfactory and sensory signal transduction, smooth-muscle contraction, and neuronal and cardiac excitation. Recent advances have been made in the molecular identification of these channels and in the identification of channel activators and inhibitors.

  • Chloride channels activated by GABA (γ-aminobutyric acid) and glycine (ionotropic receptors) modulate important physiological functions in the central and peripheral nervous system. The large diversity of ionotropic GABA and glycine receptors provide an opportunity to develop drugs to treat various neurological disorders.

  • Volume-sensitive chloride channels remain to be identified at the molecular level. These channels may be important pharmacological targets in treating cancer and degenerative disorders.

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References

  1. 1.

    & Conotoxins down under. Toxicon 48, 780–798 (2006).

  2. 2.

    et al. Voltage-gated ion channels and gating modifier toxins. Toxicon 49, 124–141 (2007).

  3. 3.

    , , , & Structural basis of spectral shifts in the yellow-emission variants of green fluorescent protein. Structure 6, 1267–1277 (1998).

  4. 4.

    , , , & Mechanism and cellular applications of a green fluorescent protein-based halide sensor. J. Biol. Chem. 275, 6047–6050 (2000).

  5. 5.

    , & Green fluorescent protein-based halide indicators with improved chloride and iodide affinities. FEBS Lett. 499, 220–224 (2001).

  6. 6.

    et al. Thiazolidinone CFTR inhibitor identified by high-throughput screening blocks cholera toxin-induced intestinal fluid secretion. J. Clin. Invest. 110, 1651–1658 (2002). Identification of the first chloride-channel inhibitor with nanomolar potency and high selectivity. Proof of concept that CFTR inhibitors are useful for diarrhoea treatment.

  7. 7.

    , & Cell-based assay for high-throughput quantitative screening of CFTR chloride transport agonists. Am. J. Physiol. 281, C1734–C1742 (2001).

  8. 8.

    , , & Small-molecule screen identifies inhibitors of a human intestinal calcium-activated chloride channel. Mol. Pharmacol. 73, 758–768 (2008).

  9. 9.

    , , & Molecular structure and physiological function of chloride channels. Physiol. Rev. 82, 503–568 (2002).

  10. 10.

    & Molecular targeting of CFTR as a therapeutic approach to cystic fibrosis. Trends Pharmacol. Sci. 28, 334–341 (2007).

  11. 11.

    & Structure and function of the CFTR chloride channel. Physiol. Rev. 79, S23–S45 (1999).

  12. 12.

    , & The ABC protein turned chloride channel whose failure causes cystic fibrosis. Nature 440, 477–483 (2006).

  13. 13.

    et al. Identification of the cystic fibrosis gene: chromosome walking and jumping. Science 245, 1059–1065 (1989).

  14. 14.

    & Patterns of GI disease in adulthood associated with mutations in the CFTR gene. Gut 56, 1153–1163 (2007).

  15. 15.

    & CFTR pharmacology and its role in intestinal fluid secretion. Curr. Opin. Pharmacol. 3, 594–599 (2003).

  16. 16.

    Antisecretory drugs for diarrheal disease. Dig. Dis. 24, 47–58 (2006).

  17. 17.

    , , & The relationship between cell proliferation, Cl secretion, and renal cyst growth: a study using CFTR inhibitors. Kidney Int. 66, 1926–1938 (2004).

  18. 18.

    , , , & The cystic fibrosis transmembrane conductance regulator mediates transepithelial fluid secretion by human autosomal dominant polycystic kidney disease epithelium in vitro. Kidney Int. 50, 208–218 (1996).

  19. 19.

    , , & Pharmacology of CFTR chloride channel activity. Physiol. Rev. 79, S109–S144 (1999).

  20. 20.

    et al. Altered channel gating mechanism for CFTR inhibition by a high-affinity thiazolidinone blocker. FEBS Lett. 558, 52–56 (2004).

  21. 21.

    et al. Evidence for direct CFTR inhibition by CFTRinh-172 based on arginine 347 mutagenesis. Biochem. J. 413, 135–142 (2008).

  22. 22.

    , , , & In vivo pharmacology and antidiarrheal efficacy of a thiazolidinone CFTR inhibitor in rodents. J. Pharm. Sci. 94, 134–143 (2005).

  23. 23.

    & Thiazolidinone CFTR inhibitors with improved water solubility identified by structure-activity analysis. Bioorg. Med. Chem. 16, 8187–8195 (2008).

  24. 24.

    et al. Discovery of glycine hydrazide pore-occluding CFTR inhibitors: mechanism, structure-activity analysis, and in vivo efficacy. J. Gen. Physiol. 124, 125–137 (2004).

  25. 25.

    , , & Luminally-active, nonabsorbable CFTR inhibitors as potential therapy to reduce intestinal fluid losses in cholera. FASEB J. 20, 130–132 (2006).

  26. 26.

    , , , & Lectin conjugates as potent, nonabsorbable CFTR inhibitors for reducing intestinal fluid secretion in cholera. Gastroenterology 132, 1234–1244 (2007).

  27. 27.

    , , , & Nanomolar CFTR inhibition by pore-occluding divalent polyethylene glycol-malonic acid hydrazides. Chem. Biol. 15, 718–728 (2008).

  28. 28.

    , , & Prevention of toxin-induced intestinal ion and fluid secretion by a small-molecule CFTR inhibitor. Gastroenterology 126, 511–519 (2004).

  29. 29.

    , , , & Molecular pathogenesis of autosomal dominant polycystic kidney disease. Expert. Rev. Mol. Med. 8, 1–22 (2006).

  30. 30.

    , & Volume progression in autosomal dominant polycystic kidney disease: the major factor determining clinical outcomes. Clin. J. Am. Soc. Nephrol. 1, 148–157 (2006).

  31. 31.

    , , , & Small-molecule CFTR inhibitors slow cyst growth in polycystic kidney disease. J. Am. Soc. Nephrol. 19, 1300–1310 (2008).

  32. 32.

    & CFTR-regulated chloride transport at the ocular surface in living mice measured by potential differences. Invest. Opthalmol. Vis. Sci. 46, 1428–1434 (2005).

  33. 33.

    et al. High-affinity activators of cystic fibrosis transmembrane conductance regulator (CFTR) chloride conductance identified by high-throughput screening. J. Biol. Chem. 277, 37235–37241 (2002).

  34. 34.

    et al. Novel CFTR chloride channel activators identified by screening of combinatorial libraries based on flavone and benzoquinolizinium lead compounds. J. Biol. Chem. 276, 19723–19728 (2001).

  35. 35.

    et al. Processing of mutant cystic fibrosis transmembrane conductance regulator is temperature-sensitive. Nature 358, 761–764 (1992).

  36. 36.

    , & The DF508 cystic fibrosis mutation impairs domain-domain interactions and arrests post-translational folding of CFTR. Nature Struct. Mol. Biol. 12, 17–25 (2005).

  37. 37.

    et al. Altered chloride ion channel kinetics associated with the ΔF508 cystic fibrosis mutation. Nature 354, 526–528 (1991).

  38. 38.

    et al. Delta F508-CFTR channels: kinetics, activation by forskolin, and potentiation by xanthines. Am. J. Physiol. 270, C1544–C1555 (1996).

  39. 39.

    et al. Maturation and function of cystic fibrosis transmembrane conductance regulator variants bearing mutations in putative nucleotide-binding domains 1 and 2. Mol. Cell. Biol. 11, 3886–3893 (1991).

  40. 40.

    , , & Cystic fibrosis: a worldwide analysis of CFTR mutations — correlation with incidence data and application to screening. Hum. Mutat. 19, 575–606 (2002).

  41. 41.

    & Role of CFTR in airway disease. Physiol. Rev. 79, S215–S255 (1999).

  42. 42.

    , & Role of airway surface liquid and submucosal glands in cystic fibrosis lung disease. Am. J. Physiol. 284, C2–C15 (2005).

  43. 43.

    Evidence for airway surface dehydration as the initiating event in CF airway disease. J. Intern. Med. 261, 5–16 (2007).

  44. 44.

    et al. Nanomolar affinity small molecule correctors of defective ΔF508-CFTR chloride channel gating. J. Biol. Chem. 278, 35079–35085 (2003).

  45. 45.

    et al. Phenylglycine and sulfonamide correctors of defective ΔF508 and G551D cystic fibrosis transmembrane conductance regulator chloride-channel gating. Mol. Pharmacol. 67, 1797–1807 (2005).

  46. 46.

    et al. Rescue of ΔF508-CFTR trafficking and gating in human cystic fibrosis airway primary cultures by small molecules. Am. J. Physiol. 290, L1117–L1130 (2006).

  47. 47.

    et al. Curcumin, a major constituent of turmeric, corrects cystic fibrosis defects. Science 304, 600–602 (2004).

  48. 48.

    et al. Rescue of functional ΔF508-CFTR channels in cystic fibrosis epithelial cells by the α-glucosidase inhibitor miglustat. FEBS Lett. 580, 2081–2086 (2006).

  49. 49.

    et al. Sildenafil (Viagra) corrects ΔF508-CFTR location in nasal epithelial cells from patients with cystic fibrosis. Thorax 60, 55–59 (2005).

  50. 50.

    et al. Preclinical evidence that sildenafil and vardenafil activate chloride transport in cystic fibrosis. Am. J. Respir. Crit. Care Med. 177, 506–515 (2008).

  51. 51.

    et al. Curcumin stimulates cystic fibrosis transmembrane conductance regulator Cl channel activity. J. Biol. Chem. 280, 5221–5226 (2005).

  52. 52.

    et al. Evidence against the rescue of defective ΔF508-CFTR cellular processing by curcumin in cell culture and mouse models. J. Biol. Chem. 279, 40629–40633 (2004).

  53. 53.

    , & Thapsigargin or curcumin does not promote maturation of processing mutants of the ABC transporters, CFTR, and P-glycoprotein. Biochem. Biophys. Res. Commun. 325, 580–585 (2004).

  54. 54.

    et al. SERCA pump inhibitors do not correct biosynthetic arrest of ΔF508 CFTR in cystic fibrosis. Am. J. Respir. Cell Mol. Biol. 34, 355–363 (2006).

  55. 55.

    , & In vitro pharmacologic restoration of CFTR-mediated chloride transport with sodium 4-phenylbutyrate in cystic fibrosis epithelial cells containing deltaF508-CFTR. J. Clin. Invest. 100, 2457–2465 (1997).

  56. 56.

    et al. Evidence of CFTR function in cystic fibrosis after systemic administration of 4-phenylbutyrate. Mol. Ther. 6, 119–126 (2002).

  57. 57.

    et al. Small molecule correctors of defective ΔF508-CFTR cellular processing identified by high-throughput screening. J. Clin. Invest. 115, 2564–2571 (2005). Identification of the first small-molecule pharmacological chaperones to correct mutant CFTR misfolding.

  58. 58.

    et al. Potent s-cis-locked bithiazole correctors of ΔF508-CFTR cellular processing for cystic fibrosis therapy. J. Med. Chem. 51, 6044–6054 (2008).

  59. 59.

    Processing of CFTR: traversing the cellular maze — how much CFTR needs to go through to avoid cystic fibrosis? Pediatr. Pulmonol. 39, 479–491 (2005).

  60. 60.

    et al. Gentamicin-induced correction of CFTR function in patients with cystic fibrosis and CFTR stop mutations. N. Engl. J. Med. 349, 1433–1441 (2003).

  61. 61.

    et al. PTC124 targets genetic disorders caused by nonsense mutations. Nature 447, 87–91 (2007).

  62. 62.

    et al. Effectiveness of PTC124 treatment of cystic fibrosis caused by nonsense mutations: a prospective phase II trial. Lancet 372, 719–727 (2008). Describes Phase II data supporting possible efficacy of a read-through therapy for cystic fibrosis.

  63. 63.

    , & Calcium-activated chloride channels. Annu. Rev. Physiol. 67, 719–758 (2005). An excellent review of CaCCs.

  64. 64.

    et al. Regulation of calcium-activated chloride channels in smooth muscle cells: a complex picture is emerging. Can. J. Physiol. Pharmacol. 83, 541–556 (2005).

  65. 65.

    , & Neuronal Ca2+-activated Cl channels — homing in on an elusive channel species. Prog. Neurobiol. 60, 247–289 (2000).

  66. 66.

    , , & The vitelliform macular dystrophy protein defines a new family of chloride channels. Proc. Natl Acad. Sci. USA 99, 4008–4013 (2002).

  67. 67.

    , , & Two bestrophins cloned from Xenopus laevis oocytes express Ca2+-activated Cl currents. J. Biol. Chem. 278, 49563–49572 (2003).

  68. 68.

    et al. Cloning of an epithelial chloride channel from bovine trachea. J. Biol. Chem. 270, 31016–31026 (1995).

  69. 69.

    et al. Regulation of human CLC-3 channels by multifunctional Ca2+/calmodulin-dependent protein kinase. J. Biol. Chem. 276, 20093–20100 (2001).

  70. 70.

    Calcium-activated chloride channels: (un)known, (un)loved? Proc. Am. Thorac. Soc. 1, 22–27 (2004).

  71. 71.

    , , , & Calcium-dependent chloride conductance in epithelia: is there a contribution by Bestrophin? Pflugers Arch. 454, 879–889 (2007).

  72. 72.

    et al. Structure-function analysis of the bestrophin family of anion channels. J. Biol. Chem. 278, 41114–41125 (2003).

  73. 73.

    , & Mouse bestrophin-2 is a bona fide Cl channel: identification of a residue important in anion binding and conduction. J. Gen. Physiol. 123, 327–340 (2004).

  74. 74.

    , , , & The best disease-linked Cl channel hBest1 regulates CaV1 (L-type) Ca2+ channels via src-homology-binding domains. J. Neurosci. 28, 5660–5670 (2008).

  75. 75.

    et al. TMEM16A confers receptor-activated calcium-dependent chloride conductance. Nature 455, 1210–1215 (2008).

  76. 76.

    et al. TMEM16A, a membrane protein associated with calcium-dependent chloride channel activity. Science 322, 590–594 (2008).

  77. 77.

    , , & Expression cloning of TMEM16A as a calcium-activated chloride channel subunit. Cell 134, 1019–1029 (2008).

  78. 78.

    & Chloride secretion by the intestinal epithelium: molecular basis and regulatory aspects. Annu. Rev. Physiol. 62, 535–572 (2000).

  79. 79.

    et al. Diarrhea-associated HIV-1 APIs potentiate muscarinic activation of Cl secretion by T84 cells via prolongation of cytosolic Ca2+ signaling. Am. J. Physiol. 264, C998–C1008 (2004).

  80. 80.

    , & Muscarinic receptor stimulation activates a Ca2+-dependent Cl conductance in rat distal colon. J. Membr. Biol. 204, 117–127 (2005).

  81. 81.

    et al. Niflumic acid and AG-1478 reduce cigarette smoke-induced mucin synthesis: the role of hCLCA1. Chest 131, 1149–1156 (2007).

  82. 82.

    et al. Phase 2 randomized safety and efficacy trial of nebulized denufosol tetrasodium in cystic fibrosis. Am. J. Respir. Crit. Care Med. 176, 362–369 (2007).

  83. 83.

    et al. Inhalation of Moli1901 in patients with cystic fibrosis. Chest 131, 1461–1466 (2007).

  84. 84.

    , & Primary structure of Torpedo marmorata chloride channel isolated by expression cloning in Xenopus oocytes. Nature 348, 510–514 (1990). Describes the original cloning of a ClC-type chloride channel.

  85. 85.

    & Secondary active transport mediated by a prokaryotic homologue of ClC Cl channels. Nature 427, 803–807 (2004). Demonstration that a ClC-type protein functions as an electrogenic Cl/H+ antiporter. This mechanism of transport was later found in eukaryotic intracellular ClCs.

  86. 86.

    , , & Voltage-dependent electrogenic chloride/proton exchange by endosomal CLC proteins. Nature 436, 424–427 (2005).

  87. 87.

    & Chloride/proton antiporter activity of mammalian CLC proteins ClC-4 and ClC-5. Nature 436, 420–423 (2005).

  88. 88.

    , , & The Cl/H+ antiporter ClC-7 is the primary chloride permeation pathway in lysosomes. Nature 453, 788–792 (2008).

  89. 89.

    , , , & X-ray structure of a ClC chloride channel at 3.0 Å reveals the molecular basis of anion selectivity. Nature 415, 287–294 (2002).

  90. 90.

    ClC chloride channels viewed through a transporter lens. Nature 440, 484–489 (2006).

  91. 91.

    & Dimeric structure of single chloride channels from Torpedo electroplax. Proc. Natl Acad. Sci. USA 81, 2772–2775 (1984).

  92. 92.

    , & Two physically distinct pores in the dimeric ClC-0 chloride channel. Nature 383, 340–343 (1996).

  93. 93.

    , & The muscle chloride channel ClC-1 has a double-barreled appearance that is differentially affected in dominant and recessive myotonia. J. Gen. Physiol. 113, 457–468 (1999).

  94. 94.

    & Pores formed by single subunits in mixed dimers of different CLC chloride channels. J. Biol. Chem. 276, 2347–2353 (2001).

  95. 95.

    , , , & Functional and structural conservation of CBS domains from CLC chloride channels. J. Physiol. 557, 363–378 (2004).

  96. 96.

    Chloride and the endosomal-lysosomal pathway: emerging roles of CLC chloride transporters. J. Physiol. 578, 633–640 (2007).

  97. 97.

    et al. Concentration and pH dependence of skeletal muscle chloride channel ClC-1. J. Physiol. 497, 423–435 (1996).

  98. 98.

    , , & Gating of the voltage-dependent chloride channel CIC-0 by the permeant anion. Nature 373, 527–531 (1995).

  99. 99.

    , , & Role of innervation, excitability, and myogenic factors in the expression of the muscular chloride channel ClC-1. A study on normal and myotonic muscle. J. Biol. Chem. 269, 27635–27639 (1994).

  100. 100.

    Myotonia caused by mutations in the muscle chloride channel gene CLCN1. Hum. Mutat. 19, 423–434 (2002).

  101. 101.

    et al. Loss of the muscle-specific chloride channel in type 1 myotonic dystrophy due to misregulated alternative splicing. Mol. Cell 10, 45–53 (2002).

  102. 102.

    et al. Expanded CUG repeats trigger aberrant splicing of ClC-1 chloride channel pre-mRNA and hyperexcitability of skeletal muscle in myotonic dystrophy. Mol. Cell 10, 35–44 (2002).

  103. 103.

    , , & A chloride channel widely expressed in epithelial and non-epithelial cells. Nature 356, 57–60 (1992).

  104. 104.

    , , & Regions involved in the opening of CIC-2 chloride channel by voltage and cell volume. Nature 360, 759–762 (1992).

  105. 105.

    , , , & Alteration of GABAA receptor function following gene transfer of the CLC-2 chloride channel. Neuron 17, 543–551 (1996).

  106. 106.

    et al. Male germ cells and photoreceptors, both dependent on close cell-cell interactions, degenerate upon ClC-2 Cl channel disruption. EMBO J. 20, 1289–1299 (2001).

  107. 107.

    et al. Leukoencephalopathy upon disruption of the chloride channel ClC-2. J. Neurosci. 27, 6581–6589 (2007).

  108. 108.

    et al. Mutations in CLCN2 encoding a voltage-gated chloride channel are associated with idiopathic generalized epilepsies. Nature Genet. 33, 527–532 (2003).

  109. 109.

    et al. Functional evaluation of human ClC-2 chloride channel mutations associated with idiopathic generalized epilepsies. Physiol. Genomics 19, 74–83 (2004).

  110. 110.

    , , & Mechanisms of disease: the kidney-specific chloride channels ClCKA and ClCKB, the Barttin subunit, and their clinical relevance. Nature Clin. Pract. Nephrol. 4, 38–46 (2008).

  111. 111.

    et al. Mutations in the chloride channel gene, CLCNKB, cause Bartter's syndrome type III. Nature Genet. 17, 171–178 (1997).

  112. 112.

    et al. Overt nephrogenic diabetes insipidus in mice lacking the CLC-K1 chloride channel. Nature Genet. 21, 95–98 (1999).

  113. 113.

    et al. Barttin is a Cl channel beta-subunit crucial for renal Cl reabsorption and inner ear K+ secretion. Nature 414, 558–561 (2001).

  114. 114.

    et al. Mutation of BSND causes Bartter syndrome with sensorineural deafness and kidney failure. Nature Genet. 29, 310–314 (2001).

  115. 115.

    et al. Activating mutation of the renal epithelial chloride channel ClC-Kb predisposing to hypertension. Hypertension 43, 1175–1181 (2004).

  116. 116.

    , , , & A common sequence variation of the CLCNKB gene strongly activates ClC-Kb chloride channel activity. Kidney Int. 65, 190–197 (2004).

  117. 117.

    et al. Common genetic variants and haplotypes in renal CLCNKA gene are associated to salt-sensitive hypertension. Hum. Mol. Genet. 16, 1630–1638 (2007).

  118. 118.

    et al. A common molecular basis for three inherited kidney stone diseases. Nature 379, 445–449 (1996).

  119. 119.

    , & The ClC-5 chloride channel knock-out mouse — an animal model for Dent's disease. Pflugers Arch. 445, 456–462 (2003). .

  120. 120.

    , , , & ClC-5 Cl channel disruption impairs endocytosis in a mouse model for Dent's disease. Nature 408, 369–373 (2000).

  121. 121.

    et al. Loss of the ClC-7 chloride channel leads to osteopetrosis in mice and man. Cell 104, 205–215 (2001).

  122. 122.

    et al. Pharmacological characterization of chloride channels belonging to the ClC family by the use of chiral clofibric acid derivatives. Mol. Pharmacol. 58, 498–507 (2000).

  123. 123.

    , , , & Conservation of chloride channel structure revealed by an inhibitor binding site in ClC-1. Neuron 38, 47–59 (2003).

  124. 124.

    , , & Characteristics of rabbit ClC-2 current expressed in Xenopus oocytes and its contribution to volume regulation. Am. J. Physiol. 274, C500–C512 (1998).

  125. 125.

    , , & Characterization of the hyperpolarization-activated chloride current in dissociated rat sympathetic neurons. J. Physiol. 506, 665–678 (1998).

  126. 126.

    et al. Molecular determinants of differential pore blocking of kidney CLC-K chloride channels. EMBO Rep. 5, 584–589 (2004).

  127. 127.

    et al. Molecular switch for CLC-K Cl channel block/activation: optimal pharmacophoric requirements towards high-affinity ligands. Proc. Natl Acad. Sci. USA 105, 1369–1373 (2008).

  128. 128.

    et al. Activation and inhibition of kidney CLC-K chloride channels by fenamates. Mol. Pharmacol. 69, 165–173 (2006).

  129. 129.

    , , & The role of chloride channels in osteoclasts: ClC-7 as a target for osteoporosis treatment. Drug News Perspect. 18, 489–495 (2005).

  130. 130.

    et al. The chloride channel inhibitor NS3736 prevents bone resorption in ovariectomized rats without changing bone formation. J. Bone Miner. Res. 19, 1144–1153 (2004).

  131. 131.

    et al. SPI-0211 activates T84 cell chloride transport and recombinant human ClC-2 chloride currents. Am. J. Physiol. 287, C1173–C1183 (2004).

  132. 132.

    et al. Basolateral localization of native ClC-2 chloride channels in absorptive intestinal epithelial cells and basolateral sorting encoded by a CBS-2 domain di-leucine motif. J. Cell Sci. 118, 4243–4252 (2005).

  133. 133.

    , , , & Expression of the chloride channel ClC-2 in the murine small intestine epithelium. Am. J. Physiol. 279, C1787–C1794 (2000).

  134. 134.

    , , , & Additional disruption of the ClC-2 Cl channel does not exacerbate the cystic fibrosis phenotype of cystic fibrosis transmembrane conductance regulator mouse models. J. Biol. Chem. 279, 22276–22283 (2004).

  135. 135.

    & Lubiprostone, a locally acting chloride channel activator, in adult patients with chronic constipation: a double-blind, placebo-controlled, dose-ranging study to evaluate efficacy and safety. Aliment. Pharmacol. Ther. 25, 1351–1361 (2007).

  136. 136.

    et al. A synthetic prostone activates apical chloride channels in A6 epithelial cells. Am. J. Physiol. 295, G234–G251 (2008).

  137. 137.

    Molecular structure and function of the glycine receptor chloride channel. Physiol. Rev. 84, 1051–1095, (2004).

  138. 138.

    Modulating inhibitory ligand-gated ion channels. AAPS J. 8, E353–E361 (2006).

  139. 139.

    & GABA and glycine as neurotransmitters: a brief history. Br. J. Pharmacol. 147, S109–S119 (2006).

  140. 140.

    & Molecular pharmacology of the glycine receptor chloride channel. Curr. Pharm. Des. 13, 2350–2367 (2007).

  141. 141.

    , & Structural elements involved in activation of the γ-aminobutyric acid type A (GABAA) receptor. Biochem. Soc. Trans. 32, 540–546 (2004).

  142. 142.

    , , & Potassium-coupled chloride cotransport controls intracellular chloride in rat neocortical pyramidal neurons. J. Neurosci. 20, 8069–8076 (2000).

  143. 143.

    et al. Disruption of KCC2 reveals an essential role of K-Cl cotransport already in early synaptic inhibition. Neuron 30, 515–524 (2001).

  144. 144.

    et al. Point mutations in the gene encoding the α-1 subunit of the inhibitory glycine receptor cause the dominant neurologic disorder, hyperekplexia. Nature Genet. 5, 351–357 (1993).

  145. 145.

    et al. First genetic evidence of GABAA receptor dysfunction in epilepsy: a mutation in the γ-2-subunit gene. Nature Genet. 28, 46–48 (2001).

  146. 146.

    et al. Mutation of GABRA1 in an autosomal dominant form of juvenile myoclonic epilepsy. Nature Genet. 31, 184–189 (2002).

  147. 147.

    et al. A mutation in the GABAA receptor α1-subunit is associated with absence epilepsy. Ann. Neurol. 59, 983–987 (2006).

  148. 148.

    , & GABA, gamma-hydroxybutyric acid, and neurological disease. Ann. Neurol. 54, S3–S12 (2003).

  149. 149.

    et al. Selective, orally active γ-aminobutyric acidA α-5 receptor inverse agonists as cognition enhancers. J. Med. Chem. 47, 2176–2179 (2004).

  150. 150.

    & Gaboxadol — a new awakening in sleep. Curr. Opin. Pharmacol. 6, 30–36 (2006).

  151. 151.

    GABAC receptor ion channels. Clin. Exp. Pharmacol. Physiol. 31, 800–804 (2004).

  152. 152.

    , , & GABAC receptors as drug targets. Curr. Drug Targets CNS Neurol. Disord. 2, 260–268 (2003).

  153. 153.

    et al. GlyR α3: an essential target for spinal PGE2-mediated inflammatory pain sensitization. Science 304, 884–887 (2004).

  154. 154.

    et al. Ethanol potentiation of glycine-induced responses in dissociated neurons of rat ventral tegmental area. J. Pharmacol. Exp. Ther. 296, 77–83 (2001).

  155. 155.

    , , , & Glycine and γ-aminobutyric acidA receptor function is enhanced by inhaled drugs of abuse. Mol. Pharmacol. 57, 1199–1205 (2000).

  156. 156.

    & Inhibition of glycine receptor function of native neurons by aliphatic n-alcohols. Br. J. Pharmacol. 136, 629–635 (2002).

  157. 157.

    & Swelling-activated ion channels: functional regulation in cell-swelling, proliferation and apoptosis. Acta Physiol. (Oxf) 187, 27–42 (2006).

  158. 158.

    & Volume-regulatory Cl channel currents in cultured human epithelial cells. J. Physiol. 456, 351–371 (1992).

  159. 159.

    & Characterization of the voltage-dependent properties of a volume-sensitive anion conductance. J. Gen. Physiol. 105, 661–676 (1995).

  160. 160.

    Volume expansion-sensing outward-rectifier Cl channel: fresh start to the molecular identity and volume sensor. Am. J. Physiol. 273, C755–C789 (1997).

  161. 161.

    & Volume-sensitive anion channels mediate swelling-activated inositol and taurine efflux. Am. J. Physiol. 265, C1489–C1500 (1993).

  162. 162.

    , , & Cl channel blockers inhibit the volume-activated efflux of Cl and taurine in cultured neurons. Am. J. Physiol. 270, C1703–C1708 (1996).

  163. 163.

    Swelling-induced taurine transport: relationship with chloride channels, anion-exchangers and other swelling-activated transport pathways. Cell Physiol. Biochem. 21, 15–28 (2008).

  164. 164.

    et al. Volume-regulated chloride channels associated with the human multidrug-resistance P-glycoprotein. Nature 355, 830–833 (1992).

  165. 165.

    et al. New mammalian chloride channel identified by expression cloning. Nature 356, 238–241 (1992).

  166. 166.

    et al. Antisense oligonucleotides suppress cell-volume-induced activation of chloride channels. Pflugers Arch. 430, 464–470 (1995).

  167. 167.

    et al. Cell swelling stimulates cytosol to membrane transposition of ICln. J. Biol. Chem. 278, 50163–50174 (2003).

  168. 168.

    et al. Is there a link between protein pICln and volume-regulated anion channels? Biochem. J. 331, 347–349 (1998).

  169. 169.

    , , , & Molecular characterization of a swelling-induced chloride conductance regulatory protein, pICln. Cell 76, 439–448 (1994).

  170. 170.

    et al. Expression of human pICln and ClC-6 in Xenopus oocytes induces an identical endogenous chloride conductance. J. Biol. Chem. 272, 3615–3621 (1997).

  171. 171.

    , , & pICln inhibits snRNP biogenesis by binding core spliceosomal proteins. Mol. Cell. Biol. 19, 4113–4120 (1999).

  172. 172.

    , , , & Horowitz B. Molecular identification of a volume-regulated chloride channel. Nature 390, 417–421 (1997).

  173. 173.

    et al. Disruption of ClC-3, a chloride channel expressed on synaptic vesicles, leads to a loss of the hippocampus. Neuron 29, 185–196 (2001).

  174. 174.

    et al. Human ClC-3 is not the swelling-activated chloride channel involved in cell volume regulation. J. Biol. Chem. 276, 17461–17467 (2001).

  175. 175.

    et al. ClC-3 chloride channels facilitate endosomal acidification and chloride accumulation. J. Biol. Chem. 280, 1241–1247 (2005).

  176. 176.

    et al. Properties of volume-regulated anion channels in mammalian cells. Prog. Biophys. Mol. Biol. 68, 69–119 (1997).

  177. 177.

    et al. DCPIB is a novel selective blocker of I(Cl, swell) and prevents swelling-induced shortening of guinea-pig atrial action potential duration. Br. J. Pharmacol. 134, 1467–1479 (2001).

  178. 178.

    et al. Volume-sensitive chloride channels involved in apoptotic volume decrease and cell death. J. Membr. Biol. 209, 21–29 (2006).

  179. 179.

    , , , & Normotonic cell shrinkage because of disordered volume regulation is an early prerequisite to apoptosis. Proc. Natl Acad. Sci. USA 97, 9487–9492 (2000).

  180. 180.

    & Expression of TMEM16 paralogs during murine embryogenesis. Dev. Dyn. 237, 2566–2574 (2008).

  181. 181.

    , , & Fluorescent chloride indicators to assess the efficacy of CFTR cDNA delivery. Hum. Gene Ther. 10, 861–875 (1999).

  182. 182.

    in Physiology and Pathology of Chloride Transporters and Channels in the Nervous System: From Molecules to Disease (eds Alvarez-Leefmans, F. J. & Delpire, E.) (Elsevier, in the press).

  183. 183.

    & Bright future of optical assays for ion channel drug discovery. Drug Discov. Today 13, 14–22 (2008).

  184. 184.

    et al. Genetically encoded fluorescent sensors of membrane potential. Brain Cell. Biol. 36, 53–67 (2008).

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Affiliations

  1. Departments of Medicine and Physiology, University of California, San Francisco, California 94143-0521, USA.

    • Alan S. Verkman
  2. Molecular Genetics Laboratory, Giannina Gaslini Institute, 16148 Genova, Italy.

    • Luis J. V. Galietta

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  1. Search for Alan S. Verkman in:

  2. Search for Luis J. V. Galietta in:

Corresponding author

Correspondence to Alan S. Verkman.

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https://doi.org/10.1038/nrd2780

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