Submitted on February 26, 2009
Revised on April 6, 2009
Accepted on April 6, 2009
Kv2.1 and silent Kv subunits underlie the delayed rectifier K+ current in cultured small mouse DRG neurons
Elke Bocksteins1, Adam L Raes1, Gerda Van de Vijver1, Tine Bruyns1, Pierre-Paul Van Bogaert1, and Dirk J. Snyders1*
1 University of Antwerp
* To whom correspondence should be addressed. E-mail: dirk.snyders{at}ua.ac.be.
Silent voltage-gated potassium (Kv) subunits interact with Kv2 subunits and primarily modulate the voltage dependence of inactivation of these heterotetrameric channels. Both Kv2 and silent Kv subunits are expressed in the mammalian nervous system but little is known about their expression and function in sensory neurons. This study reports the presence of Kv2.1, Kv2.2 and the silent subunits Kv6.1, Kv8.1, Kv9.1, Kv9.2 and Kv9.3 mRNA in mouse dorsal root ganglia (DRG). Immunocytochemistry confirmed the protein expression of the Kv2.x and Kv9.x subunits in cultured small DRG neurons. To investigate if Kv2 and silent Kv subunits are underlying the delayed rectifier K+ current (IK) in these neurons, Kv2 mediated currents were isolated by extracellular application of rStromatoxin-1 (ScTx) or by intracellular application of Kv2 antibodies. Both the ScTx- and the anti-Kv2.1-sensitive currents displayed two components in their voltage dependence of inactivation. Together both components accounted for approximately 2/3 of the IK current. Comparison with results obtained in heterologous expression systems suggests that one component reflects homotetrameric Kv2.1 channels while the other component represents heterotetrameric Kv2.1/silent Kv channels. This observations support a physiological role for silent Kv subunits in small DRG neurons.
