Kv1.3 potassium channels are localized in the immunological synapse formed between cytotoxic and target cells

Abstract

Membrane proteins of cytotoxic T cells specifically reorganize to form an immunological synapse (IS) on interaction with their specific target. In this paper, we investigated the redistribution of Kv1.3 channels, which are the dominant voltage-gated potassium channels, in the plasma membrane of allogen-activated human cytotoxic T lymphocytes (CTLs) on interacting with their specific target cells. Kv1.3 channels bearing a FLAG epitope were expressed in the CTLs and the cell-surface distribution of fluorescently labeled ion channels was determined from confocal laser-scanning microscopy images. FLAG epitope-tagged Kv1.3 channels showed a patchy distribution in CTLs not engaged with target cells, whereas the channels were accumulated in the IS formed between CTLs and specific target lymphocytes. Localization of Kv1.3 channels in the IS might open an unrevealed possibility in the regulation of ion channel activity by signaling molecules accumulated in the IS.

Kv1.5 Association Modifies Kv1.3 Traffic and Membrane Localization

“…Kv control rest- ing membrane potential and are involved in activation and proliferation. Kv1.3 localizes in the immunological synapse and targets to different raft domains upon activation and apoptosis in T-cells (16,28). In addition to Kv1.3, Kv1.5 is also expressed in the myeloid lineage (19 -21) and exerts important physiological and pharmacological consequences in macrophages (13,20,22).…”

“…For instance, Kv1.3 targets to different rafts upon activation and apoptosis in lymphocytes (16,28). Disruption of these domains alters channel activity, and raft association seems to be dynamic (15,17,18,29,38).…”

“…Changes in this distribution, such as different lipid raft populations, determine different spatial regulations affecting the function (17,18). Although Kv1.3 targets to lipid rafts, Kv1.5 localization is uncertain (16,23,29,30). Therefore we wanted to study whether Kv1.3 and Kv1.3/Kv1.5 heteromers target to these domains.…”

“…Multiple Kv channels have affinity for lipid rafts, and different isoforms target to distinct lipid microdomains (15). In this context, Kv1.3 targets to raft domains involved in immunological synapses in T-cells (16). Furthermore, channel activity is regulated by the composition of the lipid raft (17,18).…”

Computer program for analyzing donor photobleaching FRET image series

“…One of these possibilities is the acceptor-depletion FRET technique (13,(40)(41)(42), which is a useful pixel-by-pixel based fluor- escence method. Using conventional fluorescence farfield image microscopic technique, a whole energy transfer map can be generated for cell surface receptors.…”