Title :
Distribution of traction forces associated with shape changes during amoeboid cell migration
Author :
Alonso-Latorre, B. ; Meili, Ruedi ; Bastounis, E. ; Del Álamo, J.C. ; Firtel, R. ; Lasheras, J.C.
Author_Institution :
Depts. of Mech. & Aerosp. Eng. & Bioeng., Univ. of California, La Jolla, CA, USA
Abstract :
Amoeboid motility results from the cyclic repetition of shape changes leading to periodic oscillations of the cell length (motility cycle). We analyze the dominant modes of shape change and their association to the traction forces exerted on the substrate using Principal Component Analysis (PCA) of time-lapse measurements of cell shape and traction forces in migrating Dictyostelium cells. Using wild-type cells (wt) as reference, we investigated myosin II activity by studying myosin II heavy chain null cells (mhcA-) and myosin II essential light chain null cells (mlcE-). We found that wt, mlcE-and mhcA- cells utilize similar modes of shape changes during their motility cycle, although these shape changes are implemented at a slower pace in myosin II null mutants. The number of dominant modes of shape changes is surprisingly few with only four modes accounting for 75% of the variance in all cases. The three principal shape modes are dilation/elongation, bending, and bulging of the front/back. The second mode, resulting from sideways protrusion/retraction, is associated to lateral asymmetries in the cell traction forces, and is significantly less important in mhcA-cells. These results indicate that the mechanical cycle of traction stresses and cell shape changes remains remarkably similar for all cell lines but is slowed down when myosin function is lost, probably due to a reduced control on the spatial organization of the traction stresses.
Keywords :
biomechanics; cell motility; microorganisms; molecular biophysics; principal component analysis; proteins; traction; Dictyostelium cells; PCA; amoeboid cell migration; amoeboid motility; cell length; lateral asymmetry; myosin II activity; periodic oscillations; principal component analysis; shape change modes; shape changes; time-lapse measurement; traction force distribution; traction stress; Cell Motility; actin polymerization; cell migration; dictyostelium; principal component analysis; traction stresses; Actins; Animals; Biophysics; Cell Adhesion; Cell Movement; Cell Shape; Dictyostelium; Leukocytes; Myosin Type II; Principal Component Analysis; Signal Processing, Computer-Assisted; Stress, Mechanical; Time Factors;
Conference_Titel :
Engineering in Medicine and Biology Society, 2009. EMBC 2009. Annual International Conference of the IEEE
Conference_Location :
Minneapolis, MN
Print_ISBN :
978-1-4244-3296-7
Electronic_ISBN :
1557-170X
DOI :
10.1109/IEMBS.2009.5333191