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Design principles of actin lamellipodial treadmill: lessons from the fragment

Presented by: 
Alex Mogilner
Tuesday 14th July 2015 - 09:00 to 10:00
INI Seminar Room 1
Co-authors: N Ofer (Technion), D Ben Aroush (Technion), J Allard (UC Irvine), E Abu Shah (Technion), K Keren (Technion)
Actin turnover/treadmill is the central driver of cell migration. Though biochemical players enabling actin treadmill are known, its quantitative understanding is lacking. We focused on lamellipodial fragments form fish keratocytes lacking cell body but retaining the ability to migrate. The geometric simplicity of fragments and the absence of organelles and complex actin structures allowed us to characterize quantitatively the spatial actin organization in motile fragments. We used fluorescent microscopy to measure distributions of actin filaments and monomers, as well as the distributions of barbed ends and pointed ends. We then combined the actin mapping with mathematical modeling and FRAP to understand the organization of the actin turnover and treadmill. We found that more than half of actin is not part of the rapidly turning over F-actin network but is a diffusing fraction of oligomers and monomers, most of which is not available for polymerization. Modeling suggests that such organization of the actin treadmill enables diffusion to recycle actin effectively and makes cell migration steady, yet prepared for rapid focused acceleration.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons