title: Depolarization causes the formation of a ternary complex between GlialCAM, MLC1 and ClC-2 in astrocytes: implications in megalencephalic leukoencephalopathy.
abstract: Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of leukodystrophy caused by mutations in either MLC1 or GLIALCAM. GlialCAM is necessary for the correct targeting of MLC1, but also for the targeting of the Cl- channel ClC-2. Furthermore, GlialCAM modifies ClC-2 functional properties in vitro. However, in vivo studies in GlialCAM-/- mice have shown that the modification of ClC-2 activity only occurs in oligodendrocytes, despite GlialCAM and ClC-2 being expressed in astrocytes. Thus, the relationship between GlialCAM, MLC1 and ClC-2 in astrocytes is unknown. Here, we show that GlialCAM, ClC-2 and MLC1 can form a ternary complex in cultured astrocytes, but only under depolarizing conditions. We also provide biochemical evidences that this ternary complex exists in vivo. The formation of this complex changes ClC-2 localization in the membrane and its functional properties. ClC-2 association with GlialCAM/MLC1 depends on calcium flux through L-type calcium channels and activation of calcium-dependent calpain proteases. Based on these studies, we propose that the chloride influx mediated by GlialCAM/MLC1/ClC-2 in astrocytes may be needed to compensate an excess of potassium, as occurs in conditions of high neuronal activity. We suggest that a defect in this compensation may contribute to the pathogenesis of MLC disease.
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.|Unitat de Genètica, Departament de Ciències Fisiològiques, Laboratori de Genètica Molecular, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.
authors.forename: Sònia
authors.initials: S
authors.lastname: Sirisi
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.|Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII.
authors.forename: Xabier
authors.initials: X
authors.lastname: Elorza-Vidal
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.|Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII.
authors.forename: Tanit
authors.initials: T
authors.lastname: Arnedo
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Armand-Ugón
authors.affiliation: Neurophysiology Laboratory, Physiology Unit, Departament of Biomedicine, Medical School, Institute of Neurosciences, Universitat de Barcelona, IDIBAPS, Barcelona, Spain.
authors.forename: Gerard
authors.initials: G
authors.lastname: Callejo
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Capdevila-Nortes
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.
authors.forename: Tania
authors.initials: T
authors.lastname: López-Hernández
authors.affiliation: Logopharm GmbH, Freiburg, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schulte
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.|Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Barrallo-Gimeno
authors.affiliation: Unitat de Genètica, Departament de Ciències Fisiològiques, Laboratori de Genètica Molecular, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.|Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII.
authors.forename: Virginia
authors.initials: V
authors.lastname: Nunes
authors.affiliation: Neurophysiology Laboratory, Physiology Unit, Departament of Biomedicine, Medical School, Institute of Neurosciences, Universitat de Barcelona, IDIBAPS, Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Gasull
authors.affiliation: Unitat de Fisiologia, Departament de Ciències Fisiològiques, IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.|Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII.
authors.forename: Raúl
authors.initials: R
authors.lastname: Estévez
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D001927:Brain Diseases / Q000473:pathology; D000090007:CLC-2 Chloride Channels; D020746:Calcium Channels, L-Type / Q000235:genetics; D019062:Cell Adhesion Molecules, Neuron-Glia / Q000378:metabolism*; D018118:Chloride Channels; D003560:Cysts / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D020279:Hereditary Central Nervous System Demyelinating Diseases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics
chemical_list: D000090007:CLC-2 Chloride Channels; D020746:Calcium Channels, L-Type; D019062:Cell Adhesion Molecules, Neuron-Glia; D018118:Chloride Channels; C000593181:GlialCAM protein, mouse; C425069:MLC1 protein, human; D008565:Membrane Proteins; C498927:Mlc1 protein, mouse; D009419:Nerve Tissue Proteins