PhD Exit Seminar for Medha Sharma (Harris Lab)

Emergence of a smooth interface between cytoskeleton materials explained by mathematical modeling

 Abstract

Structures and machines require smoothening of raw materials. Self-organized smoothening guides cell and tissue morphogenesis and is relevant to advanced manufacturing. Across the syncytial Drosophila embryo surface, smooth interfaces form between expanding Arp2/ 3-based actin caps and surrounding actomyosin networks, demarcating the circumferences of nascent dome-like compartments used for forming pseudocleavage furrows between dividing nuclei. We found that forming a smooth and circular boundary of the surrounding actomyosin domain requires Arp2/3 in vivo. To dissect the physical basis of this requirement, we reconstituted the interacting networks using node-based models. In simulations of actomyosin networks with local clearances in place of Arp2/3 domains, rough boundaries persisted when myosin contractility was low. With addition of expanding Arp2/3 network domains, myosin domain boundaries failed to smoothen, but accumulated myosin nodes and tension. After incorporating actomyosin mechanosensitivity, Arp2/3 network growth locally induced a surrounding contractile actomyosin ring that smoothened the interface between the cytoskeletal domains, an effect also evident in vivo. In this way, a smooth structure can emerge from the lateral interaction of irregular active materials.

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Join Zoom Meeting

Thursday, December 2nd, 2021 at 9:30 am

https://utoronto.zoom.us/j/82340299213

Meeting ID: 823 4029 9213

Host: Tony Harris (tony.harris@utoronto.ca)

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