Genetic, cellular, and functional evidence for ca2+ inflow through cav1.2 and cav1.3 channels in murine spiral ganglion neurons

Ping Lv, Hyo Jeong Kim, Jeong Han Lee, Choong Ryoul Sihn, Somayeh Fathabad Gharaie, Atefeh Mousavi-Nik, Wenying Wang, Hong Gang Wang, Michael Anne Gratton, Karen J. Doyle, Xiao Dong Zhang, Nipavan Chiamvimonvat, Ebenezer N. Yamoah

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Spiral ganglion neurons (SGNs) of the eighth nerve serve as the bridge between hair cells and the cochlear nucleus. Hair cells use Cav1.3 as the primary channel for Ca 2+ inflow to mediate transmitter release. In contrast, SGNs are equipped with multiple Ca 2+ channels to mediate Ca 2+-dependent functions. We examined directly the role of Cav1.3 channels in SGNs using Cav1.3-deficient mice (Cav1.3-/-). We revealed a surprising finding that SGNs functionally express the cardiac-specific Cav1.2, as well as neuronal Cav1.3 channels. We show that evoked action potentials recorded from SGNs show a significant decrease in the frequency of firing in Cav1.3 -/- mice compared with wild-type (Cav1.3+/+) littermates. Although Cav1.3 is the designated L-type channel in neurons, whole-cell currents recorded in isolated SGNs from Cav1.3 -/- mice showed a surprising remnant current with sensitivity toward the dihydropyridine (DHP) agonist and antagonist, and a depolarization shift in the voltage-dependent activation compared with that in the Cav1.3 +/+ mice. Indeed, direct measurement of the elementary properties of Ca 2 channels, in Cav1.3 +/+ neurons, confirmed the existence of two DHP-sensitive single-channel currents, with distinct open probabilities and conductances. We demonstrate that the DHP-sensitive current in Cav1.3 -/- mice is derived from Cav1.2 channel activity, providing for the first time, to our knowledge, functional data for the expression of Cav1.2 currents in neurons. Finally, using shRNA gene knockdown methodology, and histological analyses of SGNs from Cav1.2 +/- and Cav1.3 +/- mice, we were able to establish the differential roles of Cav1.2 and Cav1.3 in SGNs.

Original languageEnglish (US)
Pages (from-to)7383-7393
Number of pages11
JournalJournal of Neuroscience
Volume34
Issue number21
DOIs
StatePublished - 2014

Keywords

  • Action potentials
  • Calcium channels
  • Deafness
  • Hearing
  • Neuronal degeneration
  • Neuronal survival

ASJC Scopus subject areas

  • Neuroscience(all)

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    Lv, P., Kim, H. J., Lee, J. H., Sihn, C. R., Gharaie, S. F., Mousavi-Nik, A., Wang, W., Wang, H. G., Gratton, M. A., Doyle, K. J., Zhang, X. D., Chiamvimonvat, N., & Yamoah, E. N. (2014). Genetic, cellular, and functional evidence for ca2+ inflow through cav1.2 and cav1.3 channels in murine spiral ganglion neurons. Journal of Neuroscience, 34(21), 7383-7393. https://doi.org/10.1523/JNEUROSCI.5416-13.2014