Ionized calcium (Ca2+) acts as an intracellular signal which is essential to hearing. To manage this signal, Ca2+ channels and pumps are necessary. Recent studies have shown that the plasma membrane Ca2+ pump (PMCA), which is highly concentrated in the tips of the stereocilia, is the sole Ca2+ extrusion system in hair cells. Knockout mice lacking isoform 2 of the PMCA are deaf and show severe balance deficits. Mice of strains named """"""""deafwaddler"""""""" and """"""""wriggle,"""""""" which have similar deficits, have recently been found to be homozygous for a mutation in the same PMCA2 gene. Based on these findings, the proposal will explore the functional properties and specific interacting proteins of the major PMCA isoform(s) of the inner ear.
The specific aims are (1) to determine which PMCA ioforms and alternative splice variants are expressed in rodent cochlea and vestibular hair cells; (2) to determine the functional properties of the major """"""""deafwaddler"""""""" and """"""""wriggle"""""""" PMCA mutants and of additional single amino acid mutants; and (3) to identify and characterize the proteins that interact with the major PMCA ioform of the hair cells, which may be responsible for its unique localization to the stereocilia tips. These experiments will establish a new area of investigation into the role of the plasma membrane Ca2+ pump as the controller of local Ca2+ regulation in the inner ear and should lead to a better appreciation of its contribution to the process of hearing.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC004200-02
Application #
6379511
Study Section
Special Emphasis Panel (ZRG1-IFCN-6 (01))
Program Officer
Donahue, Amy
Project Start
2000-09-01
Project End
2003-08-31
Budget Start
2001-09-01
Budget End
2002-08-31
Support Year
2
Fiscal Year
2001
Total Cost
$252,386
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905
Schultz, Julie M; Yang, Yandan; Caride, Ariel J et al. (2005) Modification of human hearing loss by plasma-membrane calcium pump PMCA2. N Engl J Med 352:1557-64
Strehler, Emanuel E; Treiman, Marek (2004) Calcium pumps of plasma membrane and cell interior. Curr Mol Med 4:323-35
Wood, J David; Muchinsky, Sara J; Filoteo, Adelaida G et al. (2004) Low endolymph calcium concentrations in deafwaddler2J mice suggest that PMCA2 contributes to endolymph calcium maintenance. J Assoc Res Otolaryngol 5:99-110
Penheiter, Alan R; Caride, Ariel J; Enyedi, Agnes et al. (2002) Tryptophan 1093 is largely responsible for the slow off rate of calmodulin from plasma membrane Ca2+ pump 4b. J Biol Chem 277:17728-32
Usachev, Yuriy M; DeMarco, Steven J; Campbell, Colin et al. (2002) Bradykinin and ATP accelerate Ca(2+) efflux from rat sensory neurons via protein kinase C and the plasma membrane Ca(2+) pump isoform 4. Neuron 33:113-22
Dumont, R A; Lins, U; Filoteo, A G et al. (2001) Plasma membrane Ca2+-ATPase isoform 2a is the PMCA of hair bundles. J Neurosci 21:5066-78
Garcia, M L; Usachev, Y M; Thayer, S A et al. (2001) Plasma membrane calcium ATPase plays a role in reducing Ca(2+)-mediated cytotoxicity in PC12 cells. J Neurosci Res 64:661-9
Penheiter, A R; Filoteo, A G; Croy, C L et al. (2001) Characterization of the deafwaddler mutant of the rat plasma membrane calcium-ATPase 2. Hear Res 162:19-28