Platform: Membrane Protein Structure, Dynamics, and Interactions

UTSouthwesterm Medical School, Dallas, TX, USA.We adopted high-resolution imaging, computer vision, and mathematicalmorphologytoquantifybranchingmorphogenesisinprimaryaorticendothelialcells migrating in 3D collagen matrices. We find that myosin-II activity regu-lates both global branchcomplexity and local cell surface curvature. Myosin-IIpreferentially assembles onto cortical regions of minimal membrane curvaturewhile also acting to minimize local curvature. Analysis of temporal relation-shipsbetweenmorphometricparametersdemonstratethatcyclesofexploratorybranching,followedbybranchpruningandcellbodyadvancearedrivenbycy-clesofmyosinIIdissociationfromthecortexthatallowplasmamembranepro-trusion, followed by myosin II cortical recruitment to drive curvatureminimization. Differential association of myosin to the inner high-curvatureand outer low-curvature surfaces of branch bases control branch orientation,linking local curvature control to directional control of migration. Thus, mem-brane curvature minimization by myosin II is a critical mechanism of dynamiccell shape control for guiding migration in 3D.82-SympContractility Driven Self-Organization of the Actin CytoskeletonAlexander D. Bershadsky