ZFIN ID: ZDB-PUB-151110-7
The Stereociliary Paracrystal Is a Dynamic Cytoskeletal Scaffold In Vivo
Hwang, P., Chou, S.W., Chen, Z., McDermott, B.M.
Date: 2015
Source: Cell Reports   13(7): 1287-94 (Journal)
Registered Authors: Chou, Shih-wei, Hwang, Philsang, McDermott Jr., Brian M.
Keywords: none
MeSH Terms:
  • Animals
  • Cytoskeleton/metabolism*
  • Cytoskeleton/ultrastructure
  • Eye Proteins/metabolism
  • Hair Cells, Auditory/metabolism
  • Hair Cells, Auditory/ultrastructure
  • Microfilament Proteins/metabolism
  • Myosins/metabolism
  • Protein Transport
  • Stereocilia/metabolism*
  • Stereocilia/ultrastructure
  • Zebrafish
  • Zebrafish Proteins/metabolism
PubMed: 26549442 Full text @ Cell Rep.
Permanency of mechanosensory stereocilia may be the consequence of low protein turnover or rapid protein renewal. Here, we devise a system, using optical techniques in live zebrafish, to distinguish between these mechanisms. We demonstrate that the stereocilium's abundant actin cross-linker fascin 2b exchanges, without bias or a phosphointermediate, orders of magnitude faster (t1/2 of 76.3 s) than any other known hair bundle protein. To establish the logic of fascin 2b's exchange, we examine whether filamentous actin is dynamic and detect substantial β-actin exchange within the stereocilium's paracrystal (t1/2 of 4.08 hr). We propose that fascin 2b's behavior may enable cross-linking at fast timescales of stereocilia vibration while noninstructively facilitating the slower process of actin exchange. Furthermore, tip protein myosin XVa fully exchanges in hours (t1/2 of 11.6 hr), indicating that delivery of myosin-associated cargo occurs in mature stereocilia. These findings suggest that stereocilia permanency is underpinned by vibrant protein exchange.