Responses of the Actin Cytoskeleton to ATP Depletion and Replenishment

Wang, Exp. Cell Res. 167:16-28 (1986)

To study how energy depletion affects actin organization, 3T3 fibroblasts were microinjected with fluorescently labeled alpha-actinin, which incorporates into actin filament bundles, lamellipodia, and focal adhesions. Cells were then treated with a combination of sodium azide and deoxyglucose to deplete ATP.

Collapse of Stress Fibers upon ATP Depletion

ATP depletion causes an immediately retraction of all the lamellipodia. Actin filament bundles (stress fibers) collapse into tight aggregates over 1-2 hours. Recording time, 120 min.

Recovery of Stress Fibers upon Drug Removal

Upon the removal of sodium azide and deoxyglucose, lamellipodia reappear transiently in the same region where they retracted. Aggregates of collapsed stress fibers extend back into long bundles. Recording time, 90 min.

Recovery of Stress Fibers at A High Magnification

At high magnifications, the recovery of stress fibers appears to involve telescoping of filaments to form long bundles. Recording time, 90 min.