Dominant-negative subunits reveal potassium channel families that contribute to M-like potassium currents.
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.
Selyanko
A A
AA
Department of Pharmacology, University College London, London WC1E 6BT, United Kingdom.
Delmas
P
P
Hadley
J K
JK
Tatulian
L
L
Wood
I C
IC
Mistry
M
M
London
B
B
Brown
D A
DA
D000818:Animals; D002478:Cells, Cultured; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D015870:Gene Expression; D005799:Genes, Dominant; D006822:Hybrid Cells / Q000378:metabolism; D051659:KCNQ3 Potassium Channel; D051379:Mice; D005810:Multigene Family; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits; D051381:Rats; D017207:Rats, Sprague-Dawley; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000378:metabolism; D014162:Transfection
D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D051659:KCNQ3 Potassium Channel; C000606915:Kcnh2 protein, mouse; C496917:Kcnq3 protein, mouse; C496918:Kcnq3 protein, rat; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits; D011188:Potassium