One might think that once you’ve won your first Nobel Prize, it’s time to kick back and watch the youngsters do the dirty work of solving all of biology’s riddles. No so. Apparently, Nobel-ers don’t like to kick back at all, but continue to push the limits of our knowledge. I think they’re all wearing superhero capes underneath their biologist uniforms (plaid shirts and old jeans?). Today’s image is from the lab of Eric Wieschaus, in a paper that provides a fascinating alternative mechanism to the prevailing model of epithelial folding.
During development, groups of cells are shaped into tissues and organs in a process called morphogenesis. One of the earliest morphogenesis events is gastrulation, during which the embryo is organized into the three germ layers that will each develop into different tissues and organs. During gastrulation in the fruit fly, the dorsal side of the embryo undergoes two epithelial folds, the anterior and posterior dorsal transverse folds, at precise locations on the embryo. The current model of epithelial folding involves actin-myosin contractions that trigger the initial cell shape changes. Wang and colleagues recently found an alternative mechanism that underlies epithelial folding during fruit fly gastrulation. Specifically, Wang and colleagues found that the adherens junctions that form between epithelial cells relocate to more basal locations in the cells that initiate epithelial folding. The movement of adherens junctions, and in turn dorsal fold initiation, depends on the activity of the polarity proteins Bazooka and Par-1. In the images above, the initiation of anterior (pink arrow) and posterior (blue arrow) folds are visualized by high resolution live imaging. The localization of E-cadherin (white), a key adherens junction protein, drops from the apical surface (top of the cells) to a more basal location in the cells undergoing shape changes.
Wang, Y., Khan, Z., Kaschube, M., & Wieschaus, E. (2012). Differential positioning of adherens junctions is associated with initiation of epithelial folding Nature, 484 (7394), 390-393 DOI: 10.1038/nature10938
Adapted by permission from Macmillan Publishers Ltd, copyright ©2012