Skip to main content
NCBI home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1996 Mar 5;93(5):2203–2207. doi: 10.1073/pnas.93.5.2203

Calmodulin controls adaptation of mechanoelectrical transduction by hair cells of the bullfrog's sacculus.

R G Walker 1, A J Hudspeth 1
PMCID: PMC39935  PMID: 8700909

Abstract

Deflection of the mechanically sensitive hair bundle atop a hair cell opens transduction channels, some of which subsequently reclose during a Ca2+-dependent adaptation process. Myosin I in the hair bundle is thought to mediate this adaptation; in the bullfrog's hair cell, the relevant isozyme may be the 119-kDa amphibian myosin I beta. Because this molecule resembles other forms of myosin I, we hypothesized that calmodulin, a cytoplasmic receptor for Ca2+, regulates the ATPase activity of myosin. We identified an approximately 120-kDa calmodulin-binding protein that shares with hair-bundle myosin I the properties of being photolabeled by vanadate-trapped uridine nucleotides and immunoreactive with a monoclonal antibody raised against mammalian myosin I beta. To investigate the possibility that calmodulin mediates Ca2+-dependent adaptation, we inhibited calmodulin action and measured the results with two distinct assays. Calmodulin antagonists increased photolabeling of hair-bundle myosin I by nucleotides. In addition, when introduced into hair cells through recording electrodes, calmodulin antagonists abolished adaptation to sustained mechanical stimuli. Our evidence indicates that calmodulin binds to and controls the activity of hair-bundle myosin I, the putative adaptation motor.

Full text

PDF
2203

Images in this article

2205Fig. 1
on p.2205
2205Fig. 2
on p.2205

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Assad J. A., Corey D. P. An active motor model for adaptation by vertebrate hair cells. J Neurosci. 1992 Sep;12(9):3291–3309. doi: 10.1523/JNEUROSCI.12-09-03291.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Avraham K. B., Hasson T., Steel K. P., Kingsley D. M., Russell L. B., Mooseker M. S., Copeland N. G., Jenkins N. A. The mouse Snell's waltzer deafness gene encodes an unconventional myosin required for structural integrity of inner ear hair cells. Nat Genet. 1995 Dec;11(4):369–375. doi: 10.1038/ng1295-369. [DOI] [PubMed] [Google Scholar]
  3. Cheney R. E., Riley M. A., Mooseker M. S. Phylogenetic analysis of the myosin superfamily. Cell Motil Cytoskeleton. 1993;24(4):215–223. doi: 10.1002/cm.970240402. [DOI] [PubMed] [Google Scholar]
  4. Collins K., Sellers J. R., Matsudaira P. Calmodulin dissociation regulates brush border myosin I (110-kD-calmodulin) mechanochemical activity in vitro. J Cell Biol. 1990 Apr;110(4):1137–1147. doi: 10.1083/jcb.110.4.1137. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. DeGrado W. F., Prendergast F. G., Wolfe H. R., Jr, Cox J. A. The design, synthesis, and characterization of tight-binding inhibitors of calmodulin. J Cell Biochem. 1985;29(2):83–93. doi: 10.1002/jcb.240290204. [DOI] [PubMed] [Google Scholar]
  6. Eatock R. A., Corey D. P., Hudspeth A. J. Adaptation of mechanoelectrical transduction in hair cells of the bullfrog's sacculus. J Neurosci. 1987 Sep;7(9):2821–2836. doi: 10.1523/JNEUROSCI.07-09-02821.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Gillespie P. G., Hudspeth A. J. Adenine nucleoside diphosphates block adaptation of mechanoelectrical transduction in hair cells. Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):2710–2714. doi: 10.1073/pnas.90.7.2710. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Gillespie P. G., Hudspeth A. J. High-purity isolation of bullfrog hair bundles and subcellular and topological localization of constituent proteins. J Cell Biol. 1991 Feb;112(4):625–640. doi: 10.1083/jcb.112.4.625. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Gillespie P. G., Wagner M. C., Hudspeth A. J. Identification of a 120 kd hair-bundle myosin located near stereociliary tips. Neuron. 1993 Oct;11(4):581–594. doi: 10.1016/0896-6273(93)90071-x. [DOI] [PubMed] [Google Scholar]
  10. Hacohen N., Assad J. A., Smith W. J., Corey D. P. Regulation of tension on hair-cell transduction channels: displacement and calcium dependence. J Neurosci. 1989 Nov;9(11):3988–3997. doi: 10.1523/JNEUROSCI.09-11-03988.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Hasson T., Heintzelman M. B., Santos-Sacchi J., Corey D. P., Mooseker M. S. Expression in cochlea and retina of myosin VIIa, the gene product defective in Usher syndrome type 1B. Proc Natl Acad Sci U S A. 1995 Oct 10;92(21):9815–9819. doi: 10.1073/pnas.92.21.9815. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Howard J., Hudspeth A. J. Mechanical relaxation of the hair bundle mediates adaptation in mechanoelectrical transduction by the bullfrog's saccular hair cell. Proc Natl Acad Sci U S A. 1987 May;84(9):3064–3068. doi: 10.1073/pnas.84.9.3064. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hudspeth A. J., Gillespie P. G. Pulling springs to tune transduction: adaptation by hair cells. Neuron. 1994 Jan;12(1):1–9. doi: 10.1016/0896-6273(94)90147-3. [DOI] [PubMed] [Google Scholar]
  14. Hudspeth A. J. How the ear's works work. Nature. 1989 Oct 5;341(6241):397–404. doi: 10.1038/341397a0. [DOI] [PubMed] [Google Scholar]
  15. Lumpkin E. A., Hudspeth A. J. Detection of Ca2+ entry through mechanosensitive channels localizes the site of mechanoelectrical transduction in hair cells. Proc Natl Acad Sci U S A. 1995 Oct 24;92(22):10297–10301. doi: 10.1073/pnas.92.22.10297. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Metcalf A. B., Chelliah Y., Hudspeth A. J. Molecular cloning of a myosin I beta isozyme that may mediate adaptation by hair cells of the bullfrog's internal ear. Proc Natl Acad Sci U S A. 1994 Dec 6;91(25):11821–11825. doi: 10.1073/pnas.91.25.11821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Pollard T. D., Doberstein S. K., Zot H. G. Myosin-I. Annu Rev Physiol. 1991;53:653–681. doi: 10.1146/annurev.ph.53.030191.003253. [DOI] [PubMed] [Google Scholar]
  18. Shepherd G. M., Barres B. A., Corey D. P. "Bundle blot" purification and initial protein characterization of hair cell stereocilia. Proc Natl Acad Sci U S A. 1989 Jul;86(13):4973–4977. doi: 10.1073/pnas.86.13.4973. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Swanljung-Collins H., Collins J. H. Ca2+ stimulates the Mg2(+)-ATPase activity of brush border myosin I with three or four calmodulin light chains but inhibits with less than two bound. J Biol Chem. 1991 Jan 15;266(2):1312–1319. [PubMed] [Google Scholar]
  20. Wagner M. C., Barylko B., Albanesi J. P. Tissue distribution and subcellular localization of mammalian myosin I. J Cell Biol. 1992 Oct;119(1):163–170. doi: 10.1083/jcb.119.1.163. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Walker R. G., Hudspeth A. J., Gillespie P. G. Calmodulin and calmodulin-binding proteins in hair bundles. Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):2807–2811. doi: 10.1073/pnas.90.7.2807. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES