title: Chloride influx provokes lamellipodium formation in microglial cells.
abstract: Lamellipodium extension and retraction is the driving force for cell migration. Although several studies document that activation of chloride channels are essential in cell migration, little is known about their contribution in lamellipodium formation. To address this question, we characterized chloride channels and transporters by whole cell recording and RT-PCR, respectively, as well as quantified lamellipodium formation in murine primary microglial cells as well as the microglial cell-line, BV-2, using time-lapse microscopy. The repertoire of chloride conducting pathways in BV-2 cells included, swelling-activated chloride channels as well as the KCl cotransporters, KCC1, KCC2, KCC3, and KCC4. Swelling-activated chloride channels were either activated by a hypoosmotic solution or by a high KCl saline, which promotes K(+) and Cl(-) influx instead of efflux by KCCs. Conductance through swelling-activated chloride channels was completely blocked by flufenamic acid (200 microM), SITS (1 mM) and DIOA (10 microM). By exposing primary microglial cells or BV-2 cells to a high KCl saline, we observed a local swelling, which developed into a prominent lamellipodium. Blockade of chloride influx by flufenamic acid (200 microM) or DIOA (10 microM) as well as incubation of cells in a chloride-free high K(+) saline suppressed formation of a lamellipodium. We assume that local swellings, established by an increase in chloride influx, are a general principle in formation of lamellipodia in eukaryotic cells.
authors.affiliation: Department of Cell Biology, Paris-Lodron- University of Salzburg, Salzburg, Austria.
authors.forename: Susanna
authors.initials: S
authors.lastname: Zierler
authors.forename: Eva
authors.initials: E
authors.lastname: Frei
authors.forename: Stephan
authors.initials: S
authors.lastname: Grissmer
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Kerschbaum
mesh_terms: D000818:Animals; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects; D018118:Chloride Channels / Q000378:metabolism*; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D049990:Membrane Transport Modulators / Q000494:pharmacology; D051379:Mice; D017628:Microglia / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D018118:Chloride Channels; D049990:Membrane Transport Modulators; D012965:Sodium Chloride; D011188:Potassium