This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.061267v1 90/6/2199    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Coughlin, M. F. Articles by Fredberg, J. J. Search for Related Content PubMed PubMed Citation Articles by Coughlin, M. F. Articles by Fredberg, J. J.

Filamin-A and Rheological Properties of Cultured Melanoma Cells

Physiology Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts

Correspondence: Address reprint requests to Dr. Mark F. Coughlin, Tel.: 617-432-2610; E-mail: mcoughli{at}hsph.harvard.edu.

Here we report the rheological properties of cultured hsFLNa (filamin-A)-expressing (FIL+) and hsFLNa-deficient (FIL–) melanoma cells. Using magnetic twisting cytometry over a wide range of probing frequencies, and targeting either cortical or deeper cytoskeletal structures, we found that differences in stiffness of FIL+ versus FIL– cells were remarkably small. When probed through deep cytoskeletal structures, FIL+ cells were, at most, 30% stiffer than FIL– cells, whereas when probed through more peripheral cytoskeletal structures FIL– cells were not different except at very high frequencies. The loss tangent, expressed as an effective cytoskeletal temperature, was systematically greater in FIL– than FIL+ cells, but these differences were small and showed that the FIL+ cells were only slightly closer to a solidlike state. To quantify cytoskeletal remodeling, we measured spontaneous motions of beads bound to cortical cytoskeletal structures and found no difference in FIL+ versus FIL– cells. Although mechanical differences between FIL+ and FIL– cells were evident both in cortical and deeper structures, these differences were far smaller than expected based on measurements of the rheology of purified actin-filamin solutions. These findings do not rule out an important contribution of filamin to the mechanical properties of the cortical cytoskeleton, but suggest that effects of filamin in the cortex are not exerted on the length scale of the probe used here. These findings would appear to rule out any important contribution of filamin to the bulk mechanical properties of the cytoplasm, however. Although filamin is present in the cytoplasm, it may be inactive, its mechanical effects may be small compared with other crosslinkers, or mechanical properties of the matrix may be dominated by an overriding role of cytoskeletal prestress.

This article has been cited by other articles:

				G. T. Charras, M. Coughlin, T. J. Mitchison, and L. Mahadevan Life and Times of a Cellular Bleb Biophys. J., March 1, 2008; 94(5): 1836 - 1853. [Abstract] [Full Text] [PDF]

				K. S. Kolahi and M. R. K. Mofrad Molecular Mechanics of Filamin's Rod Domain Biophys. J., February 1, 2008; 94(3): 1075 - 1083. [Abstract] [Full Text] [PDF]