[Abstract Title]. - Society for Neuroscience

Disclosures: W.C. de Groat, None; A. Sculptoreanu , None.
Poster
234. A-Type Potassium Channels
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 234.18/C42
Topic: B.04.f. Channel trafficking
Support: NIH/NIGMS R01 GM83335
Title: Dendritic localization of Shal (Kv4) K+ channels is mediated by the novel interactor SIDL
Authors: J. C. CHAUFTY, F. DIAO, G. WARO, *S. L. TSUNODA;
Boston Univ., Boston, MA
Abstract: Shal K + (Kv4) channels are localized exclusively to somato-dendritic regions of
neurons, where they function as key determinants of dendritic excitability. Kv4 channels have
been shown to influence the integration of post-synaptic potentials, the shape of mEPSCs, the
inhibition backpropagating action potentials into dendrites, as well as the induction of long-term
potentiation. Although the function of Shal channels is clearly dependent on their somatodendritic
localization, little is known about the mechanisms and proteins involved in achieving
this polarized distribution. Dendritic localization of Shal channels, however, has been shown to
be dependent on an evolutionarily conserved di-leucine motif (LL-motif) found in all Kv4
channels. Here, we identify the novel Drosophila protein, SIDL, as the first target protein of this
conserved LL-motif. We show that SIDL is a nervous system specific protein, which interacts
specifically with the LL-motif of Drosophila and mouse Shal channels and co-localizes with
GFP-Shal channels. To test the role of SIDL in Shal channel localization, we use the projection
neurons (PNs) of the adult Drosophila brain as a model for polarized targeting. We first show
that GFP-Shal is restricted to the cell bodies and dendrites of PNs, confirming that the somatodendritic
localization of Shal channels is conserved in Drosophila. Next, we show that deletion
of the LL-motif on Shal channels leads to a loss of polarized targeting in vivo. To examine the
role of SIDL in the dendritic localization of Shal channels, we obtained a transgenic strain
expressing an hpRNA predicted to knock-down expression of SIDL. We show that SIDL is
indeed knocked-down, and as a consequence, these flies display a severe loss of GFP-Shal
channels in PN dendrites. We further explore the role of SIDL in Shal channel localization by
generating a transgenic line expressing the C-terminus of SIDL (SIDLC), which contains the
Shal binding site. We predict that over-expression of SIDLC will compete with endogenous
SIDL protein for binding Shal channels. With the disruption of the SIDL-Shal interaction, we
again observe an absence of GFP-Shal signal in dendrites of PNs. Together, our data