RT Journal Article
SR Electronic
T1 Interdependent Roles for Accessory KChIP2, KChIP3, and KChIP4 Subunits in the Generation of Kv4-Encoded <em>I</em><sub>A</sub> Channels in Cortical Pyramidal Neurons
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 13644
OP 13655
DO 10.1523/JNEUROSCI.2487-10.2010
VO 30
IS 41
A1 Aaron J. Norris
A1 Nicholas C. Foeger
A1 Jeanne M. Nerbonne
YR 2010
UL http://www.jneurosci.org/content/30/41/13644.abstract
AB The rapidly activating and inactivating voltage-dependent outward K+ (Kv) current, IA, is widely expressed in central and peripheral neurons. IA has long been recognized to play important roles in determining neuronal firing properties and regulating neuronal excitability. Previous work demonstrated that Kv4.2 and Kv4.3 α-subunits are the primary determinants of IA in mouse cortical pyramidal neurons. Accumulating evidence indicates that native neuronal Kv4 channels function in macromolecular protein complexes that contain accessory subunits and other regulatory molecules. The K+ channel interacting proteins (KChIPs) are among the identified Kv4 channel accessory subunits and are thought to be important for the formation and functioning of neuronal Kv4 channel complexes. Molecular genetic, biochemical, and electrophysiological approaches were exploited in the experiments described here to examine directly the roles of KChIPs in the generation of functional Kv4-encoded IA channels. These combined experiments revealed that KChIP2, KChIP3, and KChIP4 are robustly expressed in adult mouse posterior (visual) cortex and that all three proteins coimmunoprecipitate with Kv4.2. In addition, in cortical pyramidal neurons from mice lacking KChIP3 (KChIP3−/−), mean IA densities were reduced modestly, whereas in mean IA densities in KChIP2−/− and WT neurons were not significantly different. Interestingly, in both KChIP3−/− and KChIP2−/− cortices, the expression levels of the other KChIPs (KChIP2 and 4 or KChIP3 and 4, respectively) were increased. In neurons expressing constructs to mediate simultaneous RNA interference-induced reductions in the expression of KChIP2, 3, and 4, IA densities were markedly reduced and Kv current remodeling was evident.