In cochlear inner hair cells (IHCs), Cav1.3 L-type voltage-gated Ca2+ channels mediate Ca2+ signals that trigger exocytosis of neurotransmitter from IHCs onto auditory nerve afferents. This function of Cav1.3 is crucial for hearing: loss-of-function alterations in Cav1.3 cause deafness in humans and animal models. Cav1.3 channels exhibit distinct properties in IHCs compared to other cell-types, but little is known about what underlies these differences or their relevance for sound encoding by the IHCs. Filling this gap in knowledge is expected to reveal fundamental processes that are required for the unique role of Cav1.3 channels at this first synapse in the auditory pathway. The long-term goal of our research is to define the mechanisms that regulate voltage- gated Cav Ca2+ channels in order to discover what causes, and how to cure, human disease. To this end, we have identified new forms of Cav1.3 modulation in IHCs. First, we found that the cell-surface density of Cav1.3 channels in IHCs is controlled by interactions with harmonin, a protein implicated in the pathogenesis of Usher syndrome. Harmonin enhances degradation of Cav1.3 by the ubiquitin-proteosome (UPS) system, and this process is disrupted in a mouse model of Usher syndrome. Second, we discovered that CaBP2, a Ca2+ binding related to calmodulin (CaM), inhibits Ca2+-dependent inactivation of Cav1.3;this effect is impaired by a human mutation in the CaBP2 gene that causes autosomal-recessive hearing loss. Third, we found that Cav1.3 associates with RIBEYE, the major component of """"""""ribbon"""""""" synapses in IHCs and other sensory cell-types. This interaction may regulate not only the localization, but also the function of Cav1.3 at the IHC active zone. Based on our findings, we hypothesize that the macromolecular assembly of Cav1.3 with proteins such as harmonin, CaBP2, and RIBEYE, dictate the strength and localization of Ca2+ signals in IHCs, and is therefore crucial for auditory transmission. The objective of this proposal is to test this hypothesis using molecular, genetic, and electrophysiological techniques. The rationale is that the proposed research will reveal essential signaling complexes that shape the synaptic function of IHCs, and how dysregulation of such complexes may contribute to the pathophysiology of inherited or acquired forms of hearing loss.

Public Health Relevance

The proposed research will characterize the mechanisms and physiological significance of factors that modulate voltage-gated Ca2+ channels in auditory hair cells. We will elucidate new cellular and molecular mechanisms, which may be altered in inherited forms of human hearing loss.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-MDCN-J (04))
Program Officer
Freeman, Nancy
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Iowa
Schools of Medicine
Iowa City
United States
Zip Code
Zhu, Lu; Almaça, Joana; Dadi, Prasanna K et al. (2017) ?-arrestin-2 is an essential regulator of pancreatic ?-cell function under physiological and pathophysiological conditions. Nat Commun 8:14295
Wang, Xiaohan; Marks, Christian R; Perfitt, Tyler L et al. (2017) A novel mechanism for Ca2+/calmodulin-dependent protein kinase II targeting to L-type Ca2+ channels that initiates long-range signaling to the nucleus. J Biol Chem 292:17324-17336
Wang, Shiyi; Stanika, Ruslan I; Wang, Xiaohan et al. (2017) Densin-180 Controls the Trafficking and Signaling of L-Type Voltage-Gated Cav1.2 Ca2+ Channels at Excitatory Synapses. J Neurosci 37:4679-4691
Krueger, Jamie N; Moore, Shannon J; Parent, Rachel et al. (2017) A novel mouse model of the aged brain: Over-expression of the L-type voltage-gated calcium channel CaV1.3. Behav Brain Res 322:241-249
Yang, Tian; Scholl, Elizabeth S; Pan, Ning et al. (2016) Expression and Localization of CaBP Ca2+ Binding Proteins in the Mouse Cochlea. PLoS One 11:e0147495
Hardie, Jason; Lee, Amy (2016) Decalmodulation of Cav1 channels by CaBPs. Channels (Austin) 10:33-7
Haeseleer, Françoise; Williams, Brittany; Lee, Amy (2016) Characterization of C-terminal Splice Variants of Cav1.4 Ca2+ Channels in Human Retina. J Biol Chem 291:15663-73
Thomas, Jessica R; Lee, Amy (2016) Measuring Ca2+-Dependent Modulation of Voltage-Gated Ca2+ Channels in HEK-293T Cells. Cold Spring Harb Protoc 2016:pdb.prot087213
Stanika, Ruslan; Campiglio, Marta; Pinggera, Alexandra et al. (2016) Splice variants of the CaV1.3 L-type calcium channel regulate dendritic spine morphology. Sci Rep 6:34528
Scharinger, Anja; Eckrich, Stephanie; Vandael, David H et al. (2015) Cell-type-specific tuning of Cav1.3 Ca(2+)-channels by a C-terminal automodulatory domain. Front Cell Neurosci 9:309

Showing the most recent 10 out of 35 publications