Dennis Breitsprecher

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Vasodilator-stimulated phosphoprotein (VASP) is a key regulator of dynamic actin structures like filopodia and lamellipodia, but its precise function in their formation is controversial. Using in vitro TIRF microscopy, we show for the first time that both human and Dictyostelium VASP are directly involved in accelerating filament elongation by delivering(More)
Filopodia are prominent cell surface projections filled with bundles of linear actin filaments that drive their protrusion. These structures are considered important sensory organelles, for instance in neuronal growth cones or during the fusion of sheets of epithelial tissues. In addition, they can serve a precursor function in adhesion site or stress fibre(More)
Cell migration is initiated by lamellipodia-membrane-enclosed sheets of cytoplasm containing densely packed actin filament networks. Although the molecular details of network turnover remain obscure, recent work points towards key roles in filament nucleation for Arp2/3 complex and its activator WAVE complex. Here, we combine fluorescence recovery after(More)
Cell migration entails protrusion of lamellipodia, densely packed networks of actin filaments at the cell front. Filaments are generated by nucleation, likely mediated by Arp2/3 complex and its activator Scar/WAVE. It is unclear whether formins contribute to lamellipodial actin filament nucleation or serve as elongators of filaments nucleated by Arp2/3(More)
Nuclear actin and actin-related proteins (Arps) are integral components of various chromatin-remodelling complexes. Actin in such nuclear assemblies does not form filaments but associates in defined complexes, for instance with Arp4 and Arp8 in the INO80 remodeller. To understand the relationship between nuclear actin and its associated Arps and to test the(More)
Actin filament severing is critical for the dynamic turnover of cellular actin networks. Cofilin severs filaments, but additional factors may be required to increase severing efficiency in vivo. Srv2/cyclase-associated protein (CAP) is a widely expressed protein with a role in binding and recycling actin monomers ascribed to domains in its C-terminus(More)
Interacting sets of actin assembly factors work together in cells, but the underlying mechanisms have remained obscure. We used triple-color single-molecule fluorescence microscopy to image the tumor suppressor adenomatous polyposis coli (APC) and the formin mDia1 during filament assembly. Complexes consisting of APC, mDia1, and actin monomers initiated(More)
Formins are a conserved family of actin assembly-promoting factors with diverse biological roles, but how their activities are regulated in vivo is not well understood. In Saccharomyces cerevisiae, the formins Bni1 and Bnr1 are required for the assembly of actin cables and polarized cell growth. Proper cable assembly further requires Bud6. Previously it was(More)
Ena/VASP proteins are implicated in a variety of fundamental cellular processes including axon guidance and cell migration. In vitro, they enhance elongation of actin filaments, but at rates differing in nearly an order of magnitude according to species, raising questions about the molecular determinants of rate control. Chimeras from fast and slow(More)
Cells use a large repertoire of proteins to remodel the actin cytoskeleton. Depending on the proteins involved, F-actin is organized in specialized protrusions such as lamellipodia or filopodia, which serve diverse functions in cell migration and sensing. Although factors responsible for directed filament assembly in filopodia have been extensively(More)