Ondrej Maxian

Our group uses mathematical modeling and simulation to uncover the principles of self-organization in the actin cytoskeleton. Composed of actin filaments, cross linkers, and myosin motors, the cytoskeleton generates and sustains mechanical forces capable of dividing, polarizing, and moving the cell, thus shaping embryonic development, cancer cell metastasis, and wound healing. Regulation of the cytoskeleton is often viewed in a “linear” manner, where steps in a signaling cascade yield a network with the organization necessary for the task at hand. Recent evidence, however, has demonstrated that cytoskeletal organization actually emerges from a complex microscopic interplay between actin assembly, myosin-induced contractility, and activator-inhibitor coupling of actin with its regulators. A fundamental question is how the cell manipulates these molecular-scale interactions to turn the cytoskeleton into a semi-autonomous machine, able to sense and correct mistakes, adapt to new surroundings, and process information from its environment.

The challenge in studying cytoskeletal self-organization is fundamentally one of scale. The quantities of interest, such as patterns of actin and myosin, are read out on the cell scale, but are controlled by biochemical and mechanical processes that occur on the much smaller molecular scale. Because there is a host of intermediate complexity in between the two scales, mathematical models and simulations, where the ingredients and physics are known a priori based on user input, are an important tool to understand how organization can emerge from a set of well-defined components and physical processes. Our group is developing tools for modeling and simulation of the actin cytoskeleton, then using these tools to bridge the gaps between molecular-scale and cell-scale imaging data, inferring how mechanical and biochemical processes happening on the smallest scales shape what happens on the largest ones.

Publications

1. "Actin network heterogeneity tunes activator-inhibitor dynamics at the cell cortex" (Under review). Maxian O., Dinner A., and Munro E. (2025).
2. "A simulation platform for slender, semiflexible, and inextensible fibers with Brownian hydrodynamics and steric repulsion" Maxian, O., & Donev, A. Physics of Fluids 2024, 36(12).
3. "Simulations of dynamically cross-linked actin networks: morphology, rheology, and hydrodynamic interactions" Maxian, O., Peláez, R. P., Mogilner, A., & Donev, A. PLoS computational biology. 2021, 17(12), e1009240