2003 Fiscal Year Final Research Report Summary
in vivo Dynamics of filamin A-crosslinked actin-based cytoskeletons and function of their mechanical responses
| Project/Area Number |
14580695
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
ITO Tadanao Kyoto Univ., School of Science, Associate Professor, 大学院・理学研究科, 助教授 (90093187)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAZAKI Masahito Shizuoka Univ., Science, Associate Professor, 理学部, 助教授 (70200665)
OHASHI Kazuyo Chiba Univ., Science, Professor, 理学部, 教授 (90114248)
KAWABATA Kazushige Hokkaido Univ., School of Science, Professor, 大学院・理学研究科, 教授 (20261274)
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| Project Period (FY) |
2002 – 2003
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| Keywords | actin-based cytoskeleton / filamin A / filamin A-deficient cell / cell motility / cellular stiffness / cell division / osmotic response / Le Chatelier principle |
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| Research Abstract |
(1) Filamin A (FLNa) organizes actin filaments into 3-D orthogonal networks in cell cortex. In this study, to clarify the role of FLNa in cell movement, we directed our attention to the cell mobility and the cell stiffness by comparing FLNa-deficient human melanoma cells (M2) and MZ sub-line expressing FLNa (A7). The cellular movement was observed for several days by using phase contrast microscopy equipped with an incubational system. Based on the statistical analysis, we found that A7 cells had much higher mobility compared with M2 cells. The cellular stiffness was measured by using Mechanical Scanning Probe Microscopy (M-SPM), which can provide us spatial distribution of elasticity in a sub-micrometer resolution. The cellular stiffness of A7 cells was about 5.5 kPa, which was more than twice that of M2 cells (2.2 kPa). In according to our previous study, the degree of stiffness imaged by the M-SPM corresponds to the intracellular tension acting along the stress fibers. Therefore, the intracellular tension in A7 cells produces larger traction force to the substrate, and causes higher mobility compared with M2 cells. Furthermore, immunofluorescent observation revealed that A7 cells formed the stress fibers while M2 cells did not, indicating M2 cells were not able to form the distinct stress fibers. Our results suggest that FLNa not only forms actin gels but also stabilizes the stress fibers, and increases the cell mobility and stiffness.
(2) Actin-based cytoskeleton responds to osmotic stress across a cell membrane so as to keep the cell volume constant. No conventional theory could account for this phenomenon. We have analyzed it with formulating the entropy of the system under the osmotic stress, and showed for the first time that the Le Chatelier principle governs such response of actin-based cytoskeleton to osmotic stress.
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Research Products
(2 results)
