May 14, 2012

Transformers may have been the hot toy in the 80s and I definitely remember coveting my big brother’s collection, but they have nothing on the cool ability of cells to completely transform themselves. During epithelial remodeling, a polarized epithelial cell transforms itself into a migratory cell….they truly are “more than meets the eye” (“robots in disguise!” ptchoo ptchoo!). Today’s stunning images are from a paper describing the cytoskeletal changes that drive this transformation.

Epithelial remodeling is the transformation of an epithelial cell into a migratory cell, a process that occurs throughout development. Although it is known that dramatic cytoskeletal changes drive epithelial remodeling, it wasn’t previously understood how these changes occur in a three-dimensional tissue. Gierke and Wittmann recently used high resolution imaging of cultured 3D epithelial cysts to track cytoskeletal changes during morphogenesis. After triggering an epithelial-to-mesenchymal (migratory) transition in the cysts, Gierke and Wittmann found that the growth rate of microtubules increased prior to any visible changes in cell shape, and that microtubules reorganize and grow into cell extensions during epithelial remodeling. In addition, this microtubule reorganization requires the function of EB1, a protein that binds to the plus-end of growing microtubules and can regulate the interaction of microtubules with the cortex of the cell. The images above show cell extensions in cysts triggered to undergo an epithelial-to-mesenchymal transition (actin filaments are labeled). Control extensions (top row) continuously grow over time, with actin-rich lamellipodia at the tip. Without EB1 (bottom row), extensions lack a single actin-rich tip and instead have multiple protrusions that do not grow.
Gierke, S., & Wittmann, T. (2012). EB1-Recruited Microtubule +TIP Complexes Coordinate Protrusion Dynamics during 3D Epithelial Remodeling Current Biology, 22 (9), 753-762 DOI: 10.1016/j.cub.2012.02.069
 Copyright ©2012 Elsevier Ltd. All rights reserved

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