From Piezosystem Jena, Inc.
Inner ear hair cells detect sound through deflection
of mechanosensory stereocilia. Each stereocilium
is supported by a paracrystalline array of parallel
actin filaments that are packed more densely
at the base, forming a rootlet extending into the
cell body. The function of rootlets and the molecules
responsible for their formation are unknown.
We found that TRIOBP, a cytoskeleton-associated
protein mutated in human hereditary deafness
DFNB28, is localized to rootlets. In vitro, purified
TRIOBP isoform 4 protein organizes actin filaments
into uniquely dense bundles reminiscent of rootlets
but distinct from bundles formed by espin, an actin
crosslinker in stereocilia. We generated mutant
Triobp mice (TriobpDex8/Dex8) that are profoundly
deaf. Stereocilia of TriobpDex8/Dex8 mice develop
normally but fail to form rootlets and are easier
to deflect and damage. Thus, F-actin bundling
by TRIOBP provides durability and rigidity for normal
mechanosensitivity of stereocilia and may
contribute to resilient cytoskeletal structures el
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Conclusion This chapter on cell dynamics and the role of the actin cytoskeleton should be considered as a snapshot of a rapidly evolving field of research. In the last three years, PubMed lists 4,000...
References Abraham, V.C., V. Krishnamurthi, D.L. Taylor, and F. Lanni. 1999. The actin-based nanomachine at the leading edge of migrating cells. Biophys. J., 77:1721 32. Amann, K.J., and T.D.
James L. McGrath and C. Forbes Dewey, Jr. ABSTRACT: This chapter focuses on the mechanical structure of the cell and how it is affected by the dynamic events that shape the cytoskeleton. We pay...
F.C. MacKintosh ABSTRACT: Most plant and animal cells possess a complex structure of filamentous proteins and associated proteins and enzymes for bundling, cross-linking, and active force generation.
Actin Dynamics Abundant, essential, and discovered more than a half-century ago, actin is one of the most studied of all the proteins. Many investigations have focused on the dynamic character of...