Guided mechanochemical self-organization
Event details
| Date | 02.02.2017 |
| Hour | 10:30 › 11:30 |
| Speaker | Dr. Peter Gross, TU Dresden |
| Location | |
| Category | Conferences - Seminars |
Abstract:
Biological systems have the fascinating ability to form very intricate spatial structures. Non-linear, out-of-equilibrium processes have long been recognized for their ability to generate complex patterns, like e.g. the prominent Turing patterns. These self-organized reaction-diffusion mechanisms are thought to be at the heart of many biological patterning process, however, the impact of forces and flows on pattern formation are largely unexplored.
Here, we uncovered a new class of biological pattern-formation mechanism that is based on guided mechanochemical self-organization, in the PAR polarity establishment in the C. elegans embryo. During this stage, the C. elegans egg generates two membrane-domains. These are populated with either the anterior or the posterior PAR proteins, which coordinate the first asymmetric cell division. In this process, we identified mechanochemical feedback as a crucial network motif that couples flows in the actomyosin cytoskeleton and membrane-bound PAR proteins. Essential for this was a combination of quantitative fluorescence microscopy, cell biological perturbations and theoretical modeling. We measured the cellular and subcellular concentration dynamics of posterior and anterior PAR proteins and non-muscle myosin (NMY-2) as the mechanical force generator, along with the cortical flow field. We uncovered that the PAR domains differentially alter the binding / unbinding kinetics of NMY-2 to establish a contractility gradient and thus drive flow of the actomyosin cytoskeleton. Finally, we developed a novel physical theory for PAR polarity patterning, incorporating mechanical forces via active gel theory. We find that mechanochemical feedback between the PAR domains and the actomyosin cortex is strong enough to overcome a system-intrinsic velocity threshold of PAR polarity establishment, but not so strong that the mechanochemical system becomes unstable to spontaneous fluctuations. This study aims to provide new insight into the role of active mechanics in the biological pattern formation process.
Biological systems have the fascinating ability to form very intricate spatial structures. Non-linear, out-of-equilibrium processes have long been recognized for their ability to generate complex patterns, like e.g. the prominent Turing patterns. These self-organized reaction-diffusion mechanisms are thought to be at the heart of many biological patterning process, however, the impact of forces and flows on pattern formation are largely unexplored.
Here, we uncovered a new class of biological pattern-formation mechanism that is based on guided mechanochemical self-organization, in the PAR polarity establishment in the C. elegans embryo. During this stage, the C. elegans egg generates two membrane-domains. These are populated with either the anterior or the posterior PAR proteins, which coordinate the first asymmetric cell division. In this process, we identified mechanochemical feedback as a crucial network motif that couples flows in the actomyosin cytoskeleton and membrane-bound PAR proteins. Essential for this was a combination of quantitative fluorescence microscopy, cell biological perturbations and theoretical modeling. We measured the cellular and subcellular concentration dynamics of posterior and anterior PAR proteins and non-muscle myosin (NMY-2) as the mechanical force generator, along with the cortical flow field. We uncovered that the PAR domains differentially alter the binding / unbinding kinetics of NMY-2 to establish a contractility gradient and thus drive flow of the actomyosin cytoskeleton. Finally, we developed a novel physical theory for PAR polarity patterning, incorporating mechanical forces via active gel theory. We find that mechanochemical feedback between the PAR domains and the actomyosin cortex is strong enough to overcome a system-intrinsic velocity threshold of PAR polarity establishment, but not so strong that the mechanochemical system becomes unstable to spontaneous fluctuations. This study aims to provide new insight into the role of active mechanics in the biological pattern formation process.
Practical information
- Expert
- Free
- This event is internal
Organizer
- Prof. Benoit Deveaud, Institute of Physics
Contact
- Blandine Jérôme