Welcome to the Kovar Lab

Cells simultaneously assemble and maintain different actin cytoskeleton networks of distinct organizations and dynamics for fundamental processes such as polarization, endocytosis, motility and division. How does a shared pool of actin monomer building blocks self-organize into functionally distinct actin filament networks of specific densities and sizes within a common cellular cytoplasm? Our research group is investigating the molecular mechanisms that govern how diverse actin cytoskeleton networks self-organize through (1) competition for a limited supply of actin monomers, (2) network-specific sorting of actin binding proteins, and (3) the effects of different combinations of actin binding proteins on actin filament network organization and dynamics. We take advantage of complementary experiments in live cells and with purified components. These interdisciplinary techniques include genetics, time-lapse fluorescence microscopy of cells (movie 1, left), biochemistry, biophysics and multi-color single molecule TIRF microscopy imaging (movie 2, right).

Movie 1 (left): Effects of addition and washout of the Arp2/3 complex inhibitor CK-666 on fission yeast cells expressing the general F-actin marker Lifeact-GFP.

Movie 2 (right): First series - TIRF microscopy imaging of actin filament networks assembled from beads coated with either formin (upper left) or Arp2/3 complex activator (lower right). Second series - TIRF microscopy imaging of red-labeled Ena molecules processively elongating the barbed end of actin filaments bundled by fascin.