Differential distribution of beta- and gamma-actin in guinea-pig cochlear sensory and supporting cells

Hear Res. 2005 Sep;207(1-2):22-34. doi: 10.1016/j.heares.2005.05.006.


Sensory and supporting cells of the mammalian organ of Corti have cytoskeletons containing beta- and gamma-actin isoforms which have been described as having differing intracellular distributions in chick cochlear hair cells. Here, we have used post-embedding immunogold labelling for beta- and gamma-actin to investigate semiquantitatively how they are distributed in the guinea-pig cochlea and to compare different frequency locations. Amounts of beta-actin decrease and gamma-actin increase in the order, outer pillar cells, inner pillar cells, Deiters' cells and hair cells. There is also more beta-actin and less gamma-actin in outer pillar cells in higher than lower frequency regions. In hair cells, beta-actin is present in the cuticular plate but is more concentrated in the stereocilia, especially in the rootlets and towards the periphery of their shafts; labelling densities for gamma-actin differ less between these locations and it is the predominant isoform of the hair-cell lateral wall. Alignments of immunogold particles suggest beta-actin and gamma-actin form homomeric filaments. These data confirm differential distribution of these actin isoforms in the mammalian cochlea and reveal systematic differences between sensory and supporting cells. Increased expression of beta-actin in outer pillar cells towards the cochlear base may contribute to the greater stiffness of this region.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Animals
  • Cochlea / cytology
  • Cochlea / innervation
  • Cochlea / metabolism*
  • Guinea Pigs
  • Hair Cells, Auditory / metabolism
  • Hair Cells, Auditory / ultrastructure
  • Immunohistochemistry
  • Microscopy, Confocal
  • Microscopy, Electron
  • Protein Isoforms / metabolism
  • Tissue Distribution


  • Actins
  • Protein Isoforms