Dominant-negative subunits reveal potassium channel families that contribute to M-like potassium currents

被引:32
作者
Selyanko, AA
Delmas, P
Hadley, JK
Tatulian, L
Wood, IC
Mistry, M
London, B
Brown, DA
机构
[1] UCL, Dept Pharmacol, London WC1E 6BT, England
[2] Univ Pittsburgh, Med Ctr, Cardiovasc Inst, Pittsburgh, PA 15213 USA
关键词
M-current; KCNQ channels; erg channels; dominant negative; NG108-15; cells; sympathetic neurons;
D O I
10.1523/JNEUROSCI.22-05-j0001.2002
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
M-currents are K(+) currents generated by members of the KCNQ family of K(+) channels (Wang et al., 1998). However, in some cells, M-like currents may be contaminated by members of other K(+) channel gene families, such as the erg family (Meves et al., 1999; Selyanko et al., 1999). In the present experiments, we have used the acute expression of pore-defective mutants of KCNQ3 (DN-KCNQ3) and Merg1a (DN-Merg1a) as dominant negatives to separate the contributions of these two families to M-like currents in NG108-15 neuroblastoma hybrid cells and rat sympathetic neurons. Two kinetically and pharmacologically separable components of M-like current could be recorded from NG108-15 cells that were individually suppressed by DN-Merg1a and DN-KCNQ3, respectively. In contrast, only DN-KCNQ3, and not DN-Merg1a, reduced currents recorded from sympathetic neurons. Pharmacological tests suggested that the residual current in DN-KCNQ3-treated sympathetic neurons was carried by residual KCNQ channels. Ineffectiveness of DN-Merg1a in sympathetic neurons was not caused by lack of expression, as judged by confocal microscopy of Flag-tagged DN-Merg1a. These results accord with previous inferences regarding the roles of erg and KCNQ channels in generating M-like currents. This experimental approach should therefore be useful in delineating the contributions of members of these two gene families to K(+) currents in other cells.
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