Research
overview:
|
 presenting at SIAM LS22 |
| A
size-dependent transition from steady
contraction to contractile waves and spirals
in actomyosin networks with turnover We first collaborated with Prof. Kinneret Keren’s lab at Technion, who study the periodic contractile dynamics of actomyosin networks immersed in water-in-oil droplets. Alex and I designed a theoretical model of the actomyosin network as a viscous fluid with viscosity and contractile parameters that are determined by whether the network is percolated, allowing the coexistence of different local density-dependent mechanical states. Through analysis and simulation, we showed how simple changes in system geometry, particularly system size, can generate varied contractile patterns (Krishna et al. 2022, “Size-dependent transition from steady contraction to waves in actomyosin networks with turnover,” bioRxiv). Friction patterns guide actin network contraction in reconstituted actomyosin networks Most recently, Alex and I collaborated with the Cytomorpho Lab of Profs. Laurent Blanchoin and Manuel Théry to demonstrate the critical role of friction in patterning actomyosin network contraction (Colin et al. 2022, “Friction patterns guide actin network contraction,” bioRxiv). In the lab, they observe that reconstituted actomyosin networks on micropatterned surfaces self-organize such that myosin, condensed in a few spots, rapidly compacts the whole actin network. The compaction point is the center of homogeneous domains and biased to more adhesive regions of heterogeneous patterns. Experiments indicate the contraction pattern is largely insensitive to the randomized myosin distribution. We modeled the actomyosin network as a 2D deformable viscoelastic cable-network material with active contractile stresses generated by myosin spots advected by the deforming network. Analysis and simulation illuminated the reason why the adhesion, not myosin, pattern determines the compaction point. In summer '23, I traveled to the Cytomorpho Lab in Paris, France to get some hands-on practical biology lab experience; this fantastic visit gave me insight into the experimental perspective on a variety of biomechanical problems in cellular biology. A model for contractile stress fibers embedded in bulk actomyosin networks While there have been many studies on the rheology and assembly of individual stress fibers, few mathematical models have explicitly modeled the bulk actomyosin network in which stress fibers are embedded, particularly not in the case of high actin turnover. Moreover, the extent of the interplay between embedded stress fibers and contractile bulk networks is still not well understood. To address this gap, we designed a model of stress fibers embedded in bulk actomyosin networks which utilizes the immersed boundary method, allowing one to consider various stress fiber rheologies in the context of an approximately viscous, compressible, contractile bulk network. This model demonstrated how bulk actomyosin networks mediate long-range interactions between stress fibers, as well as how perturbations of stress fibers can result in symmetry breaking of the bulk network. We are currently working on extending this work to 3D and utilizing it to explain experimental phenomena in collaboration with experimental labs. Tumor cluster coattraction is driven by the extracellular matrix This project is ongoing -- come see my talk at Cell Bio 2024 to learn more! |
