The studies proposed here focus on the function of KCNQ potassium channels in the sensory hair cells of the auditory and vestibular systems. Mutations in four of the five members of this newly discovered class of voltage-gated ion channels cause inherited human diseases. At least three of these proteins are expressed in the auditory and vestibular periphery: KCNQ1, 3 and 4. Mutations in two of them, KCNQ1 and 4, cause severe auditory dysfunction. Although the etiologies of these inherited conditions are not well understood, the profound sensory deficits imply an important role for KNCQ proteins in normal auditory function. This project has two main goals. This first goal is to correlate expression of KCNQ potassium channels with the normal physiology of auditory and vestibular hair cells. This will provide new insight into how mutations in the KCNQ gene family lead to pathological states. The second goal is to investigate the role of KCNQ channels in synaptic transmission in the vestibular periphery. Specifically, we will test the hypothesis that the type I hair cell afferent synapse utilizes a novel form of K+-dependent neurotransmission. To address these questions we have devised a common strategy. A mutation within the pore-forming region of these potassium channels acts in a dominant manner to block conduction. Using virus-mediated gene transfer we will express mutant KCNQ genes in cells of organotypic cultures from the mouse auditory and vestibular organs. Expression of mutant KCNQ genes in normal cells will suppress the activity of wildtype KCNQ subunits. To assay for disrupted function we will characterize the electrophysiological properties of infected cells, identified by coexpression of green fluorescent protein, and neighboring uninfected control cells. Thus, in a specific and controlled manner we will link a molecular identity with its physiologic correlate.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC005439-03
Application #
6618076
Study Section
Special Emphasis Panel (ZRG1-IFCN-6 (01))
Program Officer
Freeman, Nancy
Project Start
2001-09-01
Project End
2006-07-31
Budget Start
2003-08-01
Budget End
2004-07-31
Support Year
3
Fiscal Year
2003
Total Cost
$296,000
Indirect Cost
Name
University of Virginia
Department
Neurosciences
Type
Schools of Medicine
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
Akyuz, Nurunisa; Holt, Jeffrey R (2016) Plug-N-Play: Mechanotransduction Goes Modular. Neuron 89:1128-1130
Géléoc, Gwenaëlle S G; Holt, Jeffrey R (2014) Sound strategies for hearing restoration. Science 344:1241062
Horwitz, Geoffrey C; Risner-Janiczek, Jessica R; Holt, Jeffrey R (2014) Mechanotransduction and hyperpolarization-activated currents contribute to spontaneous activity in mouse vestibular ganglion neurons. J Gen Physiol 143:481-97
Zou, Junhuang; Zheng, Tihua; Ren, Chongyu et al. (2014) Deletion of PDZD7 disrupts the Usher syndrome type 2 protein complex in cochlear hair cells and causes hearing loss in mice. Hum Mol Genet 23:2374-90
Pan, Bifeng; Géléoc, Gwenaelle S; Asai, Yukako et al. (2013) TMC1 and TMC2 are components of the mechanotransduction channel in hair cells of the mammalian inner ear. Neuron 79:504-15
Yu, Wei-Ming; Appler, Jessica M; Kim, Ye-Hyun et al. (2013) A Gata3-Mafb transcriptional network directs post-synaptic differentiation in synapses specialized for hearing. Elife 2:e01341
Kim, Ye-Hyun; Holt, Jeffrey R (2013) Functional contributions of HCN channels in the primary auditory neurons of the mouse inner ear. J Gen Physiol 142:207-23
Geng, Ruishuang; Melki, Sami; Chen, Daniel H-C et al. (2012) The mechanosensory structure of the hair cell requires clarin-1, a protein encoded by Usher syndrome III causative gene. J Neurosci 32:9485-98
Levin, Michaela E; Holt, Jeffrey R (2012) The function and molecular identity of inward rectifier channels in vestibular hair cells of the mouse inner ear. J Neurophysiol 108:175-86
Holt, Jeffrey R; Vandenberghe, Luk H (2012) Gene therapy for deaf mice goes viral. Mol Ther 20:1836-7

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