Membrane proximal F-actin as a master regulator of cell polarity, signaling dynamics, and protrusion during migration
Abstract/Contents
- Abstract
- Balanced regulation of cell migration is critical for all stages of the human life cycle. Furthermore, aberrant or inhibited motility can cause dire consequences ranging from embryonic lethality to metastasis. Despite the diversity and plasticity of cell migration, almost all forms of motility depend on dynamic regulation of F-actin cytoskeleton. While there has been a lot of effort to understand the underlying signaling of prominent F-actin pools such as lamellipodia, filopodia, and stress fibers, much less is known about the role of membrane proximal actin (MPA) and membrane adhesion has on cell migration and polarization. We currently lack the tools to resolve MPA from other F-actin pools in the cell with high spatio temporal resolution. In this thesis we first develop a fluorescent biosensor to measure the density of membrane proximal F-actin, here termed MPAct. MPAct can be used to investigate the absolute differences between conditions using FRAP and lateral diffusion measurements, or as ratiometric reporters of relative MPA distribution within the same cell. Using the MPAct sensor we then made the unexpected observation that MPA was higher in the rear of cells migrating in 1D, 2D, and 3D, unlike global F-actin concentration under these same conditions. We further demonstrated this observed gradient was due to the underlying F-actin architecture and that MPA gradients strengthened existing polarity by biasing nascent protrusions to areas with low MPA. Finally, we found that increased Cofilin-mediated F-actin turnover at the front contributed to the observed gradients. These results provide a framework to understand directional persistence from a biomechanical point of view: cells will continue protruding from the existing cell front thereby creating directional "inertia." Based on the results from this study we further investigated if MPA gradients could create other types of signaling and biomechanical polarity during migrations. We found that EGFR dynamics, ERM localization, Focal adhesion turnover, and Cdc42 activity showed distinct behavior based on local MPA. These follow-up studies demonstrate how MPAct and MPA gradients can be used to clarify signaling dynamics at the plasma membrane. This work provides a new tool, the MPAct sensor, for probing the role of membrane adhesion in a variety of contexts. We further uncovered a novel role for MPA in unifying migration polarity signaling and a global and local level
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Bisaria, Anjali |
|---|---|
| Degree supervisor | Meyer, Tobias |
| Thesis advisor | Meyer, Tobias |
| Thesis advisor | Dunn, Alexander Robert |
| Thesis advisor | Ferrell, James Ellsworth |
| Thesis advisor | O'Brien, Lucy Erin, 1970- |
| Degree committee member | Dunn, Alexander Robert |
| Degree committee member | Ferrell, James Ellsworth |
| Degree committee member | O'Brien, Lucy Erin, 1970- |
| Associated with | Stanford University, Department of Chemical and Systems Biology. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Anjali Bisaria |
|---|---|
| Note | Submitted to the Department of Chemical and Systems Biology |
| Thesis | Thesis Ph.D. Stanford University 2020 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Anjali Bisaria
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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