Migration component dynamics in epithelial cell motility
|Titel||Migration component dynamics in epithelial cell motility|
|Ort||MMCM2018 - International Symposium Mechanobiology: Measuring and Modelling Cell Migration, Aachen, Germany, September 27-25, 2018.|
Cell migration is a fundamental process in development and maintenance of multicellular organisms. A coordinated assembly and release of focal adhesions has been reported to be crucial for harmonious cellular movement. Actin and myosin IIA are pivotal components of the cytoskeletal network, that work in accord with each other to facilitate directed cellular movement. In order to characterize the continuous flow of molecules as well as protein exchange behavior in distinct structures during migration, we have used photoconvertable Dendra2 fusion proteins of actin, myosin IIA and vinculin in motility stimulated primary human epithelial keratinocytes. Following the photoconverted protein incorporation into non-converted structures, we have identified cytosolic diffusion of actin monomers and their subsequent exchange into different types of stress fibers, with very low exchange rates for transversal arcs but high incorporation rates for the rear-end stress fiber. In contrast, myosin IIA mobility was rarely measureable on the cytoplasmic level. Instead, myosin signal propagation took place exclusively along the existing actin stress fiber network. This myosin propagation speed was observed to correlate with the cell’s mobility. For focal adhesions, our data confirm a faster exchange kinetics for nascent compared to mature complexes. Interestingly, the mature rear end focal adhesions were observed to switch their vinculin exchange kinetics to those of nascent ones shortly before disassembly. Furthermore, high resolution analysis indicate different distal-proximal exchange kinetics for disassembling focal adhesions at the cell rear with higher dynamics at their peripheral tips.