Role of Myosin in Cell Migration

Cells migrate by extending membrane protrusions at the leading edge of the cell and retracting the membrane at the trailing edge of the cell, thus, pushing the cell forward.

These protrusion and retraction forces are generated mainly by the motor protein myosin-II.

Its globular head regions bind filamentous actin and use energy from ATP hydrolysis to pull and contract the actin bundles.

For example, at the lamellipodial front, a type of membrane protrusion, the myosin contracts the actin filaments anchored to cell-matrix junctions.

This increased mechanical stress strengthens the junction, thus forming mature focal adhesions.

These anchorage points produce traction forces on the substratum, pushing the cell forward.

At the rear end of lamellipodia, the bipolar myosin binds actin and bridges the branched filaments.

Then, the myosin heads pull the actin filaments and reorient them parallel to the lamellipodial front, retracting the sides of the cell.

This retraction directs the rear of the cell to follow the lamellipodial front, resulting in directed cell migration.