THURSDAY, Oct. 21 (HealthDay News) -- The development of hair cell stereocilia needed for hearing can proceed normally in the absence of either β-actin or γ-actin proteins, but the lack of either protein results in progressive hearing loss with aging, according to a study in mice published Oct. 14 in PLoS Genetics.
Benjamin J. Perrin, Ph.D., of the University of Minnesota in Minneapolis, and colleagues used gene ablation to alternately knock out the genes Actb or Actg1 encoding the similar proteins β-actin or γ-actin in mouse auditory hair cell stereocilia. The researchers used auditory brainstem response to sounds to assess the hearing of the mice with the genetic deficiencies during their development stage and as they aged compared to normal mice.
The investigators found that mice without either β-actin or γ-actin had normal hair cell stereocilia development and hearing at young ages, but then developed specific types of progressive hearing loss and stereocilia degradation that differed depending on which protein was missing. With aging, the loss of β-actin most affected high frequency hearing, while the loss of γ-actin affected all frequencies more uniformly and progressed more rapidly. These results shed light on progressive hearing loss in humans believed linked to mutations affecting production of the β-actin and γ-actin proteins.
"These separate maintenance pathways are likely important for maintaining auditory function during aging and may contribute to future understanding of common forms of age-related hearing loss in humans," the authors write.
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