Naomi Courtemanche

To grow, divide, signal, move and withstand pressure, eukaryotic cells dynamically rearrange their actin cytoskeleton. The formin family of proteins nucleates and directs the elongation of unbranched actin filaments that are incorporated into cytokinetic contractile rings, filopodia and stress fibers. Most eukaryotes express multiple formin isoforms, which possess specific activities that make them uniquely suited to fulfill a particular role in the cell. Although the three formin isoforms in fission yeast each have a distinct biological function (cytokinesis, interphase cable assembly, mating), the functions of the 15 mammalian formins are far from clear. Because we lack many of the details required to understand how formins function in cells, it is not known how these proteins promote normal cellular proliferation. The Courtemanche lab aims to understand formin-mediated actin assembly using single-molecule fluorescence microscopy, spectroscopy and thermodynamic modeling. Current projects in the lab focus on addressing several questions: How do formins nucleate filaments? How do formin-bound filaments interact with other actin-binding proteins? How do sequence variations confer unique properties to formin orthologs? How do formins cooperate to polymerize bundled filaments? How do formins respond to force?