An Optogenetic Tool for the Activation of Endogenous Diaphanous-related Formins Induces Thickening of Stress Fibers Without An Increase in Contractility. Cytoskeleton, May 2013

By Megha Vaman Rao,1 Pei-Hsuan Chu,2 Klaus Michael Hahn,2,3 and Ronen Zaidel-Bar1,4*

Cytoskeleton, May 2013 00:00–00 (doi: 10.1002/cm.21115)


Rao et al RZB May2013(a)We have developed an optogenetic technique for the activation of diaphanous-related formins. Our approach is based on fusion of the light-oxygen-voltage 2 domain of Avena sativa Phototrophin1 to an isolated Diaphanous Autoregulatory Domain from mDia1. This “caged” diaphanous auto-regulatory domain was inactive in the dark but in the presence of blue light rapidly activated endogenous diaphanous-related formins.

Using an Factin reporter, we observed filopodia and lamellipodia formation as well as a steady increase in F-actin along existing stress fibers, starting within minutes of photoactivation. Interestingly, we did not observe the formation of new stress fibers.

Remarkably, a 1.9-fold increase in F-actin was not paralleled by an increase in myosin II along stress fibers and the amount of tension generated by the fibers, as judged by focal adhesion size, appeared unchanged. Our results suggest a decoupling between Factin accumulation and contractility in stress fibers and demonstrate the utility of photoactivatable diaphanous autoregulatory domain for the study of diaphanousrelated formin function in cells.

Read further about the research interests of the Zaidel-Bar group here.


1Graduate Program in Mechanobiology, Mechanobiology Institute, NUS, Singapore
2Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina
3Lineberger Comprehensive Cancer Center, UNC, Chapel Hill, North Carolina
4Department of Bioengineering, NUS, Singapore