Neuroscience 2005 Abstract
| Presentation Number: | 655.15 |
|---|---|
| Abstract Title: | Calmodulin as the putative Ca<sup>2+</sup> sensor of a nonselective cation channel from <i>Aplysia</i> bag cell neurons. |
| Authors: |
Lupinsky, D. A.*1
; Magoski, N. S.1
1Physiology, Queen's Univ., Kingston, Canada |
| Primary Theme and Topics |
Cognition and Behavior - Animal Cognition and Behavior -- Learning and memory: Invertebrates |
| Secondary Theme and Topics | Neural Excitability, Synapses, and Glia: Cellular Mechanisms<br />- Ion Channels<br />-- HCN and non-selective cation channels |
| Session: |
655. Invertebrate Learning and Memory: Molecular Mechanisms II Poster |
| Presentation Time: | Tuesday, November 15, 2005 10:00 AM-11:00 AM |
| Location: | Washington Convention Center - Hall A-C, Board # MM19 |
| Keywords: | Calmodulin, Ca2+-regulation, Mollusc, modulation |
In the bag cell neurons of Aplysia californica, activation of a non-selective cation channel initiates an afterdischarge that results in neuropeptide secretion and egg-laying behaviour. This channel is voltage-dependent and regulated by various kinases and phosphatases. We have reported (SFN abstract 86.3, 2004) that the channel is activated by Ca2+ in excised, inside-out patches. In general, Ca2+-activation of non-selective cation channels features prominently in the regulation of excitability, yet the underlying mechanism of how Ca2+ activates these conductances is unknown. For the bag cell neuron cation channel, we observed that increasing Ca2+ shifts its voltage-dependence to more hyperpolarized potentials. Moreover, the channel was not sensitive to Ba2+, pointing to calmodulin as a putative Ca2+ sensor. Calmidazolium (10µM), a calmodulin antagonist, significantly reduced channel activity at low (1µM), medium (10µM), and high (300µM) Ca2+ compared to controls. Calmodulin binding domain (50µM) also significantly decreased channel activity in low, medium, and high Ca2+ versus controls. In both cases, the effectiveness of the blocker was enhanced as Ca2+ levels were increased. Furthermore, when purified bovine calmodulin (3µM) was applied to the cytoplasmic face in 10µM Ca2+, a modest increase in channel activity was observed compared to boiled-calmodulin controls. This is not surprising, as added calmodulin may have to compete with endogenous calmodulin that has already associated with the channel during assembly. These findings suggest that calmodulin may underlie the Ca2+-activation of non-selective cation channels. In the bag cell neurons, calmodulin-mediated Ca2+-activation of the cation channel will contribute significantly to immediate and long-term neuromodulation.
Supported by CIHR, CFI, OIT
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
Copyright © 2005-2025 Society for Neuroscience; all rights reserved. Permission to republish any abstract or part of any abstract in any form must be obtained in writing by SfN office prior to publication.
