Corticotropin releasing hormone (CRH) receptors, and urocortin, a member of the CRH family of peptides, has recently been discovered expressed in outer hair cells and olivocochlear terminals, respectively. While analysis of the role played by urocorUn, the only known ligand expressed in the inner ear capable of activating the CRH receptors, has been analyzed using urocortin deficient mice, nothing is known of the developmental expression pattern or role of the CRH receptors in the inner ear. The CRH receptors are G protein coupled receptors, and stimulate the cAMP second messenger-signaling cascade. We hypothesize that activation of the CRH receptors may represent one phenomenon underlying protection from noise induced hearing loss. The mechanisms of action may include phosphorylation and inactivation of the sK2 calcium-activated apamin-sensitive potassium channel. In order to further analyze the morphological aspects of the CRH system in the cochlea, its functional role in hearing and protection from noise induced hearing loss, and finally, to assess the cellular mechanisms of action associated with activation of the CRH receptors, three specific aims are proposed. First, we will establish the developmental and adult expression pattern of the CRH receptors in the inner ear. Successful completion of the experiments of this specific aim will establish the precise identity of the cells within the inner ear that express the CRH receptors, and identify the postsynaptic elements of the urocortin immunopositive fibers at the ultra structural level. Second, we will establish the functional roles CRH plays in hearing, and whether they participate in protection of the inner ear from noise induced hearing loss.
This aim will be accomplished using mice that lack the gene for either the type 1 or the type 2 CRH receptor, or that lack both. Finally, we will use these mice to establish whether there are alterations in cAMP induced phosphorylation of targets in the outer hair cells following CRH receptors gene ablation. Success in this aim will allow us to identify individual proteins phosphorylated due to activation of the CRH receptors, as well as their role in modulating normal olivocochlear synaptic activity. This will functionally link the urocortin hormone/CRH receptor and classical ACh neurotransmitter systems together in a unified model explaining inner ear based protection from noise induced hearing loss. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC006258-02
Application #
6865643
Study Section
Auditory System Study Section (AUD)
Program Officer
Freeman, Nancy
Project Start
2004-04-01
Project End
2009-02-28
Budget Start
2005-03-01
Budget End
2006-02-28
Support Year
2
Fiscal Year
2005
Total Cost
$396,250
Indirect Cost
Name
Tufts University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
039318308
City
Boston
State
MA
Country
United States
Zip Code
02111
Vetter, Douglas E; Basappa, Johnvesly (2016) Multiplexed Isobaric Tagging Protocols for Quantitative Mass Spectrometry Approaches to Auditory Research. Methods Mol Biol 1427:109-33
Vetter, Douglas E (2015) The mammalian olivocochlear system--a legacy of non-cerebellar research in the Mugnaini lab. Cerebellum 14:557-69
Vetter, Douglas E (2015) Cellular signaling protective against noise-induced hearing loss – A role for novel intrinsic cochlear signaling involving corticotropin-releasing factor? Biochem Pharmacol 97:1-15
Maison, Stéphane F; Usubuchi, Hajime; Vetter, Douglas E et al. (2012) Contralateral-noise effects on cochlear responses in anesthetized mice are dominated by feedback from an unknown pathway. J Neurophysiol 108:491-500
Basappa, Johnvesly; Graham, Christine E; Turcan, Sevin et al. (2012) The cochlea as an independent neuroendocrine organ: expression and possible roles of a local hypothalamic-pituitary-adrenal axis-equivalent signaling system. Hear Res 288:3-18
Graham, Christine E; Basappa, Johnvesly; Turcan, Sevin et al. (2011) The cochlear CRF signaling systems and their mechanisms of action in modulating cochlear sensitivity and protection against trauma. Mol Neurobiol 44:383-406
Graham, Christine E; Vetter, Douglas E (2011) The mouse cochlea expresses a local hypothalamic-pituitary-adrenal equivalent signaling system and requires corticotropin-releasing factor receptor 1 to establish normal hair cell innervation and cochlear sensitivity. J Neurosci 31:1267-78
Turcan, Sevin; Vetter, Douglas E; Maron, Jill L et al. (2011) Mining functionally relevant gene sets for analyzing physiologically novel clinical expression data. Pac Symp Biocomput :50-61
Basappa, Johnvesly; Turcan, Sevin; Vetter, Douglas E (2010) Corticotropin-releasing factor-2 activation prevents gentamicin-induced oxidative stress in cells derived from the inner ear. J Neurosci Res 88:2976-90
Turcan, Sevin; Slonim, Donna K; Vetter, Douglas E (2010) Lack of nAChR activity depresses cochlear maturation and up-regulates GABA system components: temporal profiling of gene expression in alpha9 null mice. PLoS One 5:e9058

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