Expression and Functional Significance of the Ca2+-Activated Cl- Channel ANO6 in Dendritic Cells

摘要

biBackground/Aims /i/bMigration of dendritic cells (DCs), antigen presenting cells that link innate and adaptive immunity, is critical for initiation of immune responses. DC migration is controlled by the activity of different ion channels, which mediate Casup2+/sup flux or set the membrane potential. Moreover, cell migration requires local volume changes at the leading and rear end of travelling cells, which might be mediated by the fluxes of osmotically active solutes, including Clsup-/sup. The present study explored the functional expression, regulation and role of Clsup-/sup channels in mouse bone marrow-derived DCs. biMethods/Results /i/bIn whole-cell patch clamp experiments we detected outwardly rectifying Clsup-/sup currents which were activated by elevation of cytosolic Casup2+/sup, triggered either by ionomycin in the presence of extracellular Casup2+/sup or mobilization of Casup2+/sup by IPsub3/sub Most importantly, Casup2+/sup-activated Clsup-/sup channels (CaCCs) were activated by CCL21 (75 ng/ml), an agonist of the chemokine receptor CCR7. The currents showed sensitivity to Clsup-/sup channel blockers such as tannic acid (10 µM), digallic acid (100 µM) and more specific CaCC blockers niflumic acid (300 µM) and AO1 (20 µM). According to RT-PCR and Western blot data, Anoctamin 6 (ANO6) is expressed in DCs. Knock-down of ANO6 with siRNA led to inhibition of CaCC currents in DCs. Moreover, chemokine-induced migration of both immature and LPS-matured DCs was reduced upon ANO6 knock-down. biConclusion /i/bOur data identify ANO6 as a Casup2+/sup-activated Clsup-/sup channel in mouse DCs, show its activation upon chemokine receptor ligation and establish an important role of ANO6 in chemokine-induced DC migration.