Cell shape and polarity

Shapes in biology are the result of chemical and mechanical processes within cells, tissues, and organisms. While individual cells can develop whole-cell shape and directionality through signaling cascades, mechanical events in the cellular cytoskeleton generate and respond to shape cues at subcellular length scales. Cell protrusion, for example, yields convex curves at the front of the migrating cell. I hypothesized that cell motility and polarity processes could be modulated by shape cues in the extracellular environment.;When cells spread onto a surface patterned with adhesive and nonadhesive self assembled monolayers (SAMs), they took on the shape of the adhesive islands. By varying local and global features of the shapes, we were able to record cell behavior in terms of both cytoskeletal architecture and Golgi-to-nucleus polarity in response to shape cues. Cells responded to local features by cytoskeletal rearrangement. Lamellipodia formed at regions of convex curvature, while stress fibers formed at regions of concave curvature. Both cell polarity and cytoskeletal architecture were modulated by adhesive islands with global shape cues. Increased aspect ratio resulted in an increased percentage of cells developing polarity along the long axis of the shape. Testing cells with a combination of drugs and different shape cues established that the cytoskeleton plays a significant role in determining cell response to shape cues. Local and global shape cues were additionally able to control cytoskeletal organization in multi-cellular tissues. From this, we conclude that the cytoskeletal architecture of cells and tissues are subject to modulation by local curvature and global aspect ratio.