Mechanical behavior in living cells consistent with the tensegrity model

Alternative models of cell mechanics depict the living cell as a simple mec hanical continuum, porous filament gel, tensed cortical membrane, or tenseg rity network that maintains a stabilizing prestress through incorporation o f discrete structural elements that bear compression. Real-time microscopic analysis of cells containing GFP-labeled microtubules and associated mitoc hondria revealed that living cells behave like discrete structures composed of an interconnected network of actin microfilaments and microtubules when mechanical stresses are applied to cell surface integrin receptors, Quanti tation of cell tractional forces and cellular prestress by using traction f orce microscopy confirmed that microtubules bear compression and are respon sible for a significant portion of the cytoskeletal prestress that determin es cell shape stability under conditions in which myosin light chain phosph orylation and intracellular calcium remained unchanged. Quantitative measur ements of both static and dynamic mechanical behaviors in cells also were c onsistent with specific a priori predictions of the tensegrity model. These findings suggest that tensegrity represents a unified model of cell mechan ics that may help to explain how mechanical behaviors emerge through collec tive interactions among different cytoskeletal filaments and extracellular adhesions in living cells.