Quantitative analysis of subcellular biomechanics and mechanotransduction
Author(s)Lammerding, Jan, 1974-
Massachusetts Institute of Technology. Biological Engineering Division.
Roger Kamm and Richard Lee.
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Biological cells such as endothelial or muscle cells respond to mechanical stimulation with activation of specific intracellular and extracellular signaling pathways and cytoskeletal remodeling, a process termed mechanotransduction. Intracellular mechanosensors are thought to be activated by conformational changes induced by local cellular deformations. Since these mechanosensors have been speculated to be located in several cellular domains including the cell membrane, the cytoskeleton, and the nucleus, it is necessary to achieve a detailed understanding of subcellular mechanics. In this work, we present novel methods to independently quantify cytoskeletal displacements, mechanical coupling between the cytoskeleton and the extracellular matrix, and nuclear mechanics based on high resolution tracking of cellular structures and receptor bound magnetic beads in response to applied strain or microscopic forces. These methods were applied to study the effects of several human disease associated mutations on subcellular mechanics and to examine the interaction between known protein function and specific changes in cellular mechanical properties and mechanotransduction pathways. Initial experiments were targeted to the role of membrane adhesion receptors. Experiments with cells expressing a mutant form of the integrin-associated molecule tetraspanin CD151 revealed that CD151 plays a key role in selectively strengthening α6βl integrin-mediated adhesion to laminin-1. We then studied cytoplasmic behavior using cells from mice with an αB-Crystallin mutation (R120G) that causes desmin-related myopathy. These studies showed impaired passive cytoskeletal mechanics in adult mouse cardiac myocytes. Finally, we studied cells deficient in the nuclear envelope(cont.) protein lamin A/C and showed that lamin A/C deficient cells have increased nuclear deformation, defective mechanotransduction, and impaired viability under mechanical strain, suggesting that the tissue specific effects observed in laminopathies such as Emery-Dreifuss muscular dystrophy or Hutchinson-Gilford progeria may arise from varying degrees of impaired nuclear mechanics and transcriptional regulation. In conclusion, our methods provide new and valuable tools to examine the role of subcellular biomechanics on mechanotransduction in normal and mutant cells, leading to improved understanding of disease mechanisms associated with altered cell mechanics.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2004.Includes bibliographical references.
DepartmentMassachusetts Institute of Technology. Biological Engineering Division.
Massachusetts Institute of Technology
Biological Engineering Division.