Rac/Rho pathway regulates actin depolymerization induced by aminoglycoside antibiotics

Authors

  • Hongyan Jiang,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan
    Current affiliation:
    1. Otorhinolaryngology Hospital, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, People's Republic of China
    Search for more papers by this author
    • This first two authors contributed equally to this work.

  • Su-Hua Sha,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan
    Search for more papers by this author
    • This first two authors contributed equally to this work.

  • Jochen Schacht

    Corresponding author
    1. Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan
    • Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109-0506
    Search for more papers by this author

Abstract

Stress stimuli can lead to remodeling of the actin cytoskeleton and subsequent alteration of cell adhesion and permeation as well as cell functions and cell fate. We investigated redox-dependent Rho GTPase-linked pathways controlling the actin cytoskeleton in the inner ear of the CBA mouse, by using aminoglycoside antibiotics as a noxious stimulus that causes loss of sensory cells via the formation of reactive oxygen species. Kanamycin treatment in vivo interfered with the formation of F-actin, disturbed the arrangement of β-actin in the stereocilia of outer hair cells, and altered the intermittent adherens junction/tight junction complexes between outer hair cells and supporting cells. The drug treatment also activated Rac1 and promoted the formation of the complex of Rac1 and p67phox while decreasing the activity of RhoA and reducing the formation of the RhoA/p140mDia complex. In inner-ear-derived cell lines, expression of mutated Rac1 changed the structural arrangement of F-actin and diminished the immunoreactivity of p140mDia. These findings suggest that actin depolymerization induced by kanamycin is mediated by Rac1 activation, followed by the formation of superoxide by NADPH oxidase. These changes will ultimately contribute to aminoglycoside-induced loss of hair cells. © 2006 Wiley-Liss, Inc.

Ancillary