Distinct Roles of Frontal and Rear Adhesions in Traction Force Generation

Munevar et al., Mol. Biol. Cell.12:3947-3954 (2001)

Strong, inward traction forces appear at both the frontal and rear ends of migrating fibroblasts. They have the opposite effects of propelling versus resisting cell migration. To test if active contractions are similarly involved in both regions, migrating 3T3 fibroblasts were treated locally with an RGD peptide to induce detachment. The response of traction forces was monitored simultaneously. Local traction forces resulting from the transmission of contractions elsewhere should be sensitive to detachment at the origin.

Detachment of the Frontal Region Causes Global Silencing of Traction Forces

Detachment of one of the protruding regions inhibits local traction forces only, as expected. Detachment of both protruding regions causes global inhibition of traction forces while the tail region remains attached to the substrate. Thus tail traction forces likely come from the transmission of contractile forces at the front. Strong traction stress is represented by warm colors. Recording time, 30 min.

Detachment of the Tail Region Does not Affect Traction Forces at the Front

Detachment of the tail has either no effect or a stimulatory effect on traction forces at the front. The strong tail forces become relocated to the new rear end. Thus the tail region functions primarily as a passive anchorage site resisting active forces at the front. Recording time, 30 min.