title: Immunomodulation of voltage-dependent K+ channels in macrophages: molecular and biophysical consequences.
abstract: Voltage-dependent potassium (K(v)) channels play a pivotal role in the modulation of macrophage physiology. Macrophages are professional antigen-presenting cells and produce inflammatory and immunoactive substances that modulate the immune response. Blockage of K(v) channels by specific antagonists decreases macrophage cytokine production and inhibits proliferation. Numerous pharmacological agents exert their effects on specific target cells by modifying the activity of their plasma membrane ion channels. Investigation of the mechanisms involved in the regulation of potassium ion conduction is, therefore, essential to the understanding of potassium channel functions in the immune response to infection and inflammation. Here, we demonstrate that the biophysical properties of voltage-dependent K(+) currents are modified upon activation or immunosuppression in macrophages. This regulation is in accordance with changes in the molecular characteristics of the heterotetrameric K(v)1.3/K(v)1.5 channels, which generate the main K(v) in macrophages. An increase in K(+) current amplitude in lipopolysaccharide-activated macrophages is characterized by a faster C-type inactivation, a greater percentage of cumulative inactivation, and a more effective margatoxin (MgTx) inhibition than control cells. These biophysical parameters are related to an increase in K(v)1.3 subunits in the K(v)1.3/K(v)1.5 hybrid channel. In contrast, dexamethasone decreased the C-type inactivation, the cumulative inactivation, and the sensitivity to MgTx concomitantly with a decrease in K(v)1.3 expression. Neither of these treatments apparently altered the expression of K(v)1.5. Our results demonstrate that the immunomodulation of macrophages triggers molecular and biophysical consequences in K(v)1.3/K(v)1.5 hybrid channels by altering the subunit stoichiometry.
authors.affiliation: Molecular Physiology Laboratory, Departament de Bioquímica i Biología Molecular, Institut de Biomedicina, Universitat de Barcelona, E-08028 Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Villalonga
authors.forename: Miren
authors.initials: M
authors.lastname: David
authors.forename: Joanna
authors.initials: J
authors.lastname: Bielanska
authors.forename: Rubén
authors.initials: R
authors.lastname: Vicente
authors.forename: Núria
authors.initials: N
authors.lastname: Comes
authors.forename: Carmen
authors.initials: C
authors.lastname: Valenzuela
authors.forename: Antonio
authors.initials: A
authors.lastname: Felipe
mesh_terms: D000818:Animals; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology; D006801:Humans; D056747:Immunomodulation; D051664:Kv1.3 Potassium Channel / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051666:Kv1.5 Potassium Channel / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D008564:Membrane Potentials; D051379:Mice; D051381:Rats; D012604:Scorpion Venoms / Q000494:pharmacology
chemical_list: D051664:Kv1.3 Potassium Channel; D051666:Kv1.5 Potassium Channel; D008070:Lipopolysaccharides; D012604:Scorpion Venoms; C077910:margatoxin; D003907:Dexamethasone