Oregon Health & Science University
Actin crosslinkers are essential for the highly specified structure of hair cell stereocilia. Crosslinkers are known to influence the length, diameter and stiffness of actin-based cell protrusions, all qualities that are integral to stereocilia function. Using mass spectrometry, our lab has identified several abundant actin crosslinkers, including fascin-1, fascin-2, plastin-1, plastin-2 and plastin-3. The expression patterns and functions of these crosslinkers during hair cell development have been studied very little. Because of preliminary evidence that one of these crosslinkers, fascin-2, is developmentally regulated, I analyzed fascin-2 during stereocilia development in chicken basilar papilla. Fascin-2 mRNA and protein levels increase at each time point examined, with the largest increases during periods of stereocilia elongation. In mature bundles, fascin-2 is concentrated in the distal portion of the tallest stereocilia. At early stages of stereocilia development, fascin-2 is present in cell bodies and in stereocilia. As bundles mature, fascin-2 is exclusively localized to the distal regions of stereocilia. mRNA levels of the complement of fascin and plastin genes showed a complex developmental expression pattern: fascin-1 decreased, fascin-2 increased, plastin-1 increased, plastin-2 increased then decreased, and plastin-3 stayed constant. These findings suggest that different crosslinkers may be involved in distinct phases of stereocilia elongation and widening, as well as in the long-term structural integrity of the bundle.
Neuroscience Graduate Program
School of Medicine
Saylor, Katherine W., "Developmental regulation of fascin and plastin actin crosslinkers in the chicken basilar papilla." (2010). Scholar Archive. 568.