Abstract
CaV1.3 channels comprise a vital subdivision of L-type Ca 2+ channels: CaV1.3 channels mediate neurotransmitter release from auditory inner hair cells (IHCs), pancreatic insulin secretion, and cardiac pacemaking. Fitting with these diverse roles, CaV1.3 channels exhibit striking variability in their inactivation by intracellular Ca2+. IHCs show generally weak-to-absent Ca2+-dependent inactivation (CDI), potentially permitting audition of sustained sounds. In contrast, the strong CDI seen elsewhere likely provides critical negative feedback. Here, we explore this mysterious CDI malleability, particularly its comparative weakness in hair cells. At baseline, heterologously expressed CaV1.3 channels exhibit intense CDI, wherein each lobe of calmodulin (CaM) contributes a distinct inactivation component. Because CaM-like molecules (bearing four recognizable but not necessarily functional Ca2+- binding EF hands) can perturb the Ca2+ response of molecules regulated by CaM, we asked whether such CaM-like entities could influence CDI. We find that CaM-like calcium-binding protein (CaBP) molecules are clearly expressed within the organ of Corti. In particular, the rare subtype CaBP4 is specific to IHCs, and CaBP4 proves capable of eliminating even the potent baseline CDI of CaV1.3. CaBP4 thereby represents a plausible candidate for moderating CDI within IHCs.
Original language | English (US) |
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Pages (from-to) | 10677-10689 |
Number of pages | 13 |
Journal | Journal of Neuroscience |
Volume | 26 |
Issue number | 42 |
DOIs | |
State | Published - Oct 18 2006 |
Keywords
- Auditory
- Ca signaling
- Calmodulin
- Fret two-hybrid
- Hair cell
- Ion-channel modulation
ASJC Scopus subject areas
- General Neuroscience