Alternative splicing of the Ca(v)1.3 channel IQ domain, a molecular switch for Ca2+-dependent inactivation within auditory hair cells

J Neurosci. 2006 Oct 18;26(42):10690-9. doi: 10.1523/JNEUROSCI.2093-06.2006.

Abstract

Native Ca(V)1.3 channels within cochlear hair cells exhibit a surprising lack of Ca2+-dependent inactivation (CDI), given that heterologously expressed Ca(V)1.3 channels show marked CDI. To determine whether alternative splicing at the C terminus of the Ca(V)1.3 gene may produce a hair cell splice variant with weak CDI, we transcript-scanned mRNA obtained from rat cochlea. We found that the alternate use of exon 41 acceptor sites generated a splice variant that lost the calmodulin-binding IQ motif of the C terminus. These Ca(V)1.3(IQdelta) ("IQ deleted") channels exhibited a lack of CDI, which was independent of the type of coexpressed beta-subunits. Ca(V)1.3(IQdelta) channel immunoreactivity was preferentially localized to cochlear outer hair cells (OHCs), whereas that of Ca(V)1.3(IQfull) channels (IQ-possessing) labeled inner hair cells (IHCs). The preferential expression of Ca(V)1.3(IQdelta) within OHCs suggests that these channels may play a role in processes such as electromotility or activity-dependent gene transcription rather than neurotransmitter release, which is performed predominantly by IHCs in the cochlea.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / physiology*
  • Amino Acid Sequence
  • Animals
  • Calcium / antagonists & inhibitors*
  • Calcium / metabolism*
  • Calcium Channels / biosynthesis*
  • Calcium Channels / genetics*
  • Cochlea / metabolism
  • Hair Cells, Auditory, Inner / metabolism*
  • In Vitro Techniques
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Rats

Substances

  • Calcium Channels
  • Cacna1d protein, rat
  • Calcium