Cellular basis of mechanotransduction.

Physical forces, such as those due to gravity, are fundamental regulators of tissue development. To influence morphogenesis, mechanical forces must alter growth and function. Yet little is known about how cells convert mechanical signals into a chemical response. This presentation attempts to place the potential molecular mediators of mechanotransduction within the context of the structural complexity of living cells. Our experimental approach is based on the hypothesis that cells use tensegrity architecture to structure themselves (Ingber, 1993, 1998; Ingber and Jamieson, 1985). Most man-made structures gain their stability through continuous compression; one element weighs down on the element below due to the force of gravity. In contrast, tensegrity structures stabilize themselves through continuous tension that is distributed across all of the structural elements and balanced by a subset of these elements that resist compression locally. These internal struts generate an internal tension or “prestress” that mechanically stabilizes the entire structure. Tensegrity cell models composed of sticks and elastic string (Fig. 1) predict many complex cell behaviors, including how cells change shape when they adhere to rigid or flexible extracellular matrices (Ingber, 1993, 1998; Ingber and Jamieson, 1985). Tensegrity models also predict that cells and nuclei are hardwired to respond immediately to mechanical stresses transmitted over cell surface receptors that physically couple the cytoskeleton to the extracellular matrix and to other cells. We recently developed a technique to apply controlled