Related Experiment Video
Updated: Aug 7, 2026

Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos
Published on: April 14, 2023
FilGAP, a Rho- and ROCK-regulated GAP for Rac binds filamin A to control actin remodelling
Yasutaka Ohta1, John H Hartwig, Thomas P Stossel
1Hematology Division, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA. yohta@rics.bwh.harvard.edu
Abstract:
FilGAP is a newly recognized filamin A (FLNa)-binding RhoGTPase-activating protein. The GTPase-activating protein (GAP) activity of FilGAP is specific for Rac and FLNa binding targets FilGAP to sites of membrane protrusion, where it antagonizes Rac in vivo. Dominant-negative FilGAP constructs lacking GAP activity or knockdown of endogenous FilGAP by small interference RNA (siRNA) induce spontaneous lamellae formation and stimulate cell spreading on fibronectin. Knockdown of endogenous FilGAP abrogates ROCK-dependent suppression of lamellae. Conversely, forced expression of FilGAP induces numerous blebs around the cell periphery and a ROCK-specific inhibitor suppresses bleb formation. ROCK phosphorylates FilGAP, and this phosphorylation stimulates its RacGAP activity and is a requirement for FilGAP-mediated bleb formation. FilGAP is, therefore, a mediator of the well-established antagonism of Rac by RhoA that suppresses leading edge protrusion and promotes cell retraction to achieve cellular polarity.
Related Concept Videos
Mechanism of Filopodia Formation
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Generation of Straight or Branched Actin Filaments
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Actin Filament Depolymerization
In F-actin, the ADF/cofilin proteins...
Mechanism of Lamellipodia Formation
Formation of Higher-order Actin Filaments
The high-order actin networks...

