1.
Focal adhesions are controlled by microtubules through local contractility regulation.
Abstract:
Microtubules regulate cell polarity and migration by local activation of focal adhesion turnover, but the mechanism of this process is insufficiently understood. Molecular complexes containing KANK family proteins connect microtubules with the major component of focal adhesions, talin. Local optogenetic activation of KANK1-mediated links which promoted microtubule targeting to individual focal adhesion resulting in its centripetal sliding and rapid disassembly. The sliding is preceded by a local increase of traction force due to accumulation of myosin-II and actin in the proximity of the focal adhesion. Knockdown of Rho activator GEF-H1 prevented development of traction force and abolished sliding and disassembly of focal adhesion upon KANK activation. Other players participating in microtubule-driven KANK-dependent focal adhesion disassembly include kinases ROCK and PAK, as well as microtubules/focal adhesions associated proteins Kinesin-1, APC and αTAT. Finally, we propose a physical model of a microtubule-driven focal adhesion disruption involving local GEF-H1/RhoA/ROCK dependent activation of contractility which is consistent with experimental data.
2.
Implementing Optogenetic Modulation in Mechanotransduction.
Abstract:
Molecular optogenetic switch systems are extensively employed as a powerful tool to spatially and temporally modulate a variety of signal transduction processes in cells. However, the applications of such systems in mechanotransduction processes where the mechanosensing proteins are subject to mechanical forces of several piconewtons are poorly explored. In order to apply molecular optogenetic switch systems to mechanobiological studies, it is crucial to understand their mechanical stabilities which have yet to be quantified. In this work, we quantify a frequently used molecular optogenetic switch, iLID-nano, which is an improved light-induced dimerization between LOV2-SsrA and SspB. Our results show that the iLID-nano system can withstand forces up to 10 pN for seconds to tens of seconds that decrease as the force increases. The mechanical stability of the system suggests that it can be employed to modulate mechanotransduction processes that involve similar force ranges. We demonstrate the use of this system to control talin-mediated cell spreading and migration. Together, we establish the physical basis for utilizing the iLID-nano system in the direct control of intramolecular force transmission in cells during mechanotransduction processes.
