Actin cross-linkers and the shape of stereocilia.
Stereocilia are actin-based cellular protrusions essential for hearing. We propose that they are shaped by the detachment dynamics of actin cross-linkers, in particular espin. We account for experimentally observed stereocilium shapes, treadmilling velocity to length relationship, espin 1 localization profile, and microvillus length to espin level relationship. If the cross-linkers are allowed to reattach, our model yields a dynamical phase transition toward unbounded growth. Considering the simplified case of a noninteracting, one-filament system, we calculate the length probability distribution in the growing phase and its stationary form in a continuum approximation of the finite-length phase. Numerical simulations of interacting filaments suggest an anomalous power-law divergence of the protrusion length at the growth transition, which could be a universal feature of cross-linked depolymerizing systems.
Institut Curie, Centre de Recherche, Paris, France. martinlenz@uchicago.edu
Martin
M
Lenz
Jacques
J
Prost
Jean-François
JF
Joanny
D000199:Actins / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D022081:Cell Surface Extensions / Q000378:metabolism*; D006168:Guinea Pigs; D008954:Models, Biological; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary
D000199:Actins