| Summary: | 碩士 === 國立成功大學 === 生理學研究所 === 96 === Substrate mechanical properties play important role for the regulation of cellular function in vitro and in vivo. Previous study in our lab demonstrated that soft collagen gel induced apoptosis in epithelial cell but not in fibroblast and transformed cells. We hypothesized that the force orientation and distribution in response to substratum stiffness played important role for cell spreading and survival. In order to test the hypothesis, we cultured different cells on polyacrylamide gel with different rigidity modulus. We found that LLC-PKI (epithelia), HeLa (transformed cell) and NIH-3T3 (fibroblast) showed cell type-specific spreading ability and adaption to substratum stiffness. Immunofluorescent studies that myosin light chain phosphorylation (MLCp) was located in the center of cortical actin in LLC-PK1 cells, whereas MLCp was evenly located on stress fibers in NIH-3T3 and HeLa cells. To measure intracellular traction force in nano-Newton scale, we established micro-fabricated post array detector (mPAD). NIH-3T3 and HeLa demonstrated bi-directional force distribution with lower average force, whereas LLC-PK1 displayed higher average force without particular direction. In addition, TGF-�� induced elongated LLC-PK1 cells rearranged their traction forces similarly to that of NIH-3T3 cells. These findings indicate that epithelial cells orientate intracellular force in isotropy and generate higher intracellular tension than fibroblast or transformed cells. The isotropic cytoskeleton distribution in epithelial cells could be disadvantageous for maintaining mechanical force on soft substrate.
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