CHARACTERIZATION OF NODAL ACTIN NETWORK: FUNCTIONS OF MYOSIN II, FILAMIN A AND FORMIN DAAM1

Abstract

Actin filaments, with the aid of multiple accessory proteins, self-assemble into a variety of network patterns. In the studies done by this thesis, the organization and dynamics of actin networks in adherent cells were investigated using pharmaceutical perturbation, live cell imaging, super-resolution imaging together with molecular and biochemistry analysis. A model of nodal organization of actin network was proposed. This cytoplasmic actin nodal network is formed by actin asters cross-linked and moved by non-muscle myosin II (NMII). The crosslinker filamin A (FlnA) and the formin DAAM1 were found to co-localize with the actin asters. Based on the experimental results, a computational model was developed. The model showed the dynamic formin-filamin-actin asters that can self-organize into a contractile actomyosin network. This cytoplasmic actin network maintains the coherence and the integrity of the cell, which is the basis for cell survival, migration and many physiological functions.