Nucleation geometry governs ordered actin networks structures.
Actin filaments constitute one of the main components of cell cytoskeleton. Assembled into bundles in filopodia or in stress fibres, they play a pivotal role in eukaryotes during cell morphogenesis, adhesion and motility. The bundle emergence has been extensively related to specific actin regulators in vivo. Such dynamic modulation was also highlighted by biochemical reconstitution of the actin-network assembly, in bulk solution or with biomimetic devices. However, the question of how geometrical boundaries, such as those encountered in cells, affect the dynamic formation of highly ordered actin structures remains poorly studied. Here we demonstrate that the nucleation geometry in itself can be the principal determinant of actin-network architecture. We developed a micropatterning method that enables the spatial control of actin nucleation sites for in vitro assays. Shape, orientation and distance between nucleation regions control filament orientation and length, filament-filament interactions and filopodium-like bundle formation. Modelling of filament growth and interactions demonstrates that basic mechanical and probabilistic laws govern actin assembly in higher-order structures.
Reymann
Anne-Cécile
AC
Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, 38054, France.
Martiel
Jean-Louis
JL
Cambier
Théo
T
Blanchoin
Laurent
L
Boujemaa-Paterski
Rajaa
R
Théry
Manuel
M
D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000648:ultrastructure*; D000199:Actins / Q000737:chemistry / Q000378:metabolism; D002465:Cell Movement; D008958:Models, Molecular
D000199:Actins