Key result
Transfection of NSC-34 motoneuron-like cells with EGFP-tagged Kir4.1 increased inward rectifying K+ currents and hyperpolarized the cell membrane without toxic effects.
Why the study?
Does transfection with Kir4.1 modulate electrophysiological properties in NSC-34 cells?
Does transfection with Kir4.1 modulate electrophysiological properties in NSC-34 cells?
In vitro overexpression of the Kir4.1 channel in NSC-34 cells successfully shifts their electrophysiological properties to a more glial-like phenotype without toxicity, offering a potential tool to dampen neuronal excitability.
Heterologous expression of Kir channels offers a tool to modulate excitability of neurons which provide insight into Kir channel functions in general. Inwardly-rectifying K+ channels (Kir channels) are potential candidate proteins to hyperpolarize neuronal cell membranes. However, heterologous expression of inwardly-rectifying K+ channels has previously proven to be difficult. This was mainly due to a high toxicity of the respective Kir channel expression. We investigated the putative role of a predominantly glial-expressed, weakly rectifying Kir channel (Kir4.1 channel subunit; KCNJ10) in modulating electrophysiological properties of a motoneuron-like cell culture (NSC-34). Transfection procedures using an EGFP-tagged Kir4.1 protein in this study proved to have no toxic effects on NSC-34 cells. Using whole cell-voltage clamp, a substantial increase of inward rectifying K+ currents as well as hyperpolarization of the cell membrane was observed in Kir4.1-transfected cells. Na+ inward currents, observed in NSC-34 controls, were absent in Kir4.1/EGFP motoneuronal cells. The Kir4.1-transfection did not influence the NaV1.6 sodium channel expression. This study demonstrates the general feasibility of a heterologous expression of a weakly inward-rectifying K+ channel (Kir4.1 subunit) and shows that in vitro overexpression of Kir4.1 shifts electrophysiological properties of neuronal cells to a more glial-like phenotype and may therefore be a candidate tool to dampen excitability of neurons in experimental paradigms.
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Zschüntzsch et al. (2013) studied motoneuron-like cell culture (NSC-34). EGFP-tagged Kir4.1 protein transfection vs. NSC-34 controls was evaluated on electrophysiological properties (inward rectifying K+ currents, cell membrane hyperpolarization, Na+ inward currents). Transfection of NSC-34 motoneuron-like cells with EGFP-tagged Kir4.1 increased inward rectifying K+ currents and hyperpolarized the cell membrane without toxic effects.
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