Traction forces generated by locomoting keratocytes.

TLDR

Traction forces in fibroblasts have been observed as substrate distortions, were thought to drive forward movement, but were not detected in faster cells such as leukocytes and growth cones. The study develops a bead‑based assay to detect traction forces of rapidly moving fish keratocytes on elastic substrata. The assay uses small beads embedded in an elastic substratum to record two‑dimensional displacements caused by keratocyte traction forces. Keratoctye traction forces were absent at the front edge, peaked at the lateral margins, reaching ~2×10⁻⁸ N, and reflect lamellar contractility and contact area. Published in Nature (London) 1981, 290:249–251.

Abstract

Traction forces produced by moving fibroblasts have been observed as distortions in flexible substrata including wrinkling of thin, silicone rubber films. Traction forces generated by fibroblast lamellae were thought to represent the forces required to move the cell forwards. However, traction forces could not be detected with faster moving cell types such as leukocytes and growth cones (Harris, A. K., D. Stopak, and P. Wild. 1981. Nature (Lond.). 290:249-251). We have developed a new assay in which traction forces produced by rapidly locomoting fish keratocytes can be detected by the two-dimensional displacements of small beads embedded in the plane of an elastic substratum. Traction forces were not detected at the rapidly extending front edge of the cell. Instead the largest traction forces were exerted perpendicular to the left and right cell margins. The maximum traction forces exerted by keratocytes were estimated to be approximately 2 x 10(-8) N. The pattern of traction forces can be related to the locomotion of a single keratocyte in terms of lamellar contractility and area of close cell-substratum contact.