Branching Nucleation Meets Active Cross-Linking in Cytoskeletal Networks

For subcellular structures, being the right size is crucial. Meiotic and mitotic spindles, interphase asters, and the cell cortex need to self regulate their dimensions to function correctly in the cellular environment. However, the mechanisms by which filamentous cytoskeleton networks, formed through autocatalytic nucleation processes, determine their size remains unclear. To address this theoretically, we developed a coarse-grained model that integrates autocatalytic branching nucleation with steric interactions, crosslinking, and mechanical activity from molecular motors. By analyzing its one-dimensional version, we elucidate key concepts of length and size regulation in cytoskeletal assemblies.