SINGLE-MOLECULE STUDY OF THE FORCE-INDUCED ACTIN POLYMERIZATION MEDIATED BY FORMIN

Abstract

MECHANICAL FORCES CAN REGULATE A LARGE NUMBER OF CELLULAR FUNCTIONS VIA ACTIN CYTOSKELETON. TENSILE FORCES HAVE BEEN PREDICTED TO PROMOTE ACTIN POLYMERIZATION VIA BARBED-END FORMIN PROTEINS AS A NOVEL MECHANISM OF MECHANOTRANSDUCTION. HOWEVER, THIS HYPOTHESIS HAS NOT BEEN WELL CONCLUDED DUE TO THE LACK OF SENSITIVE APPROACH. MY PHD STUDIES, THEREFORE, AIMS TO ESTABLISH EFFECTIVE METHODS BASED ON THREE SINGLE MOLECULE MANIPULATION TOOLS: HYDRODYNAMIC FLOW, OPTICAL TWEEZERS AND MAGNETIC TWEEZERS. USING HYDRODYNAMIC FLOW, SINGLE ACTIN FILAMENTS CAN BE STRETCHED IN HIGH-THROUGHPUT. HOWEVER, THOUGH THERE MAY BE SOME WEAK DECREASE OF CRITICAL CONCENTRATION BY FORCE, ITS LOW SENSITIVITY LIMITED THE DRAWING OF CONCLUSION. OPTICAL TWEEZERS ENCOUNTERED A PROBLEM OF MULTIPLE TETHERS AND LOW STABILITY. MAGNETIC TWEEZERS, IN CONTRAST, WAS ABLE TO PULL SINGLE ACTIN FILAMENTS WITH DEFINITE FORCES AND HIGH RELIABILITY. IT ENABLES US TO MEASURE POLYMERIZATION RATES IN HIGH RESOLUTION AND INVESTIGATE PO