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Studies of the Interaction between Actins Flow and Cell Adhesion Nucleation in Macro-and Micro-scale

Ghasemi Varnamkhasti, Amir | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 50471 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firouzabadi, Bahar; Saeedi, Mohammad Saeed
  7. Abstract:
  8. The network of actin filaments is one of the three elements of the Cytoskeleton and plays a role in cell shape and migration. The actin network is dynamic; it (de)polymerizes, and in migrating and spreading cells, it is in a retrograde motion from the cell periphery toward cell nucleus. Adhesion points, which link the cytoskeleton to the extracellular matrix, interact with the actin retrograde flow. Actin filaments can be identified in two distinct regions in which their structure, flow velocity, driving force and size of the adhesions are different; the outer region is called Lamellipodium and the inner one Lamellum. In macro scale and regarding spreading cells, considering adhesions friction, we have developed models to reproduce experimentally observed flows in both regions. We could have reproduced the measurements and making predictions about the driving forces, which coincide the current understanding from experimental studies. In addition, regarding the mechanical behavior of actin network as well as the mechanical link between the regions, which both are of open questions of the literature, we could have discussed some answers. Regarding migrating cells, the common explanation for membrane protrusion is that nucleation of adhesion points reduce the actin retrograde flow, and thus harnessing the filament polymerization for membrane protrusion. We have developed a model to quantify such description and learned that the proposed mechanical mechanism is not adequate to reproduce the observed phenomenon, and probably other biochemical links which are suggested in the literature should be accounted
  9. Keywords:
  10. Lamellum ; Lamellipodium ; Actin Network ; Cytoskeleton ; Actin Retroyrade Flow ; Adhesion Points ; Membrane Protusion

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