Christoph Ballestrem

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Cellular locomotion is driven by repeated cycles of protrusion of the leading edge, formation of new matrix adhesions and retraction of the trailing edge. In this study we addressed the molecular composition and dynamics of focal complexes, formed under the leading lamellae of motile cells, and their maturation into focal adhesions. We combined(More)
The actin cytoskeleton maintains the cellular architecture and mediates cell movements. To explore actin cytoskeletal dynamics, the enhanced green fluorescent protein (EGFP) was fused to human &bgr ;-actin. The fusion protein was incorporated into actin fibers which became depolymerized upon cytochalasin B treatment. This functional EGFP-actin construct(More)
Cell-cell contacts are essential for morphogenesis and tissue function and play a vital role in mediating endothelial cohesion within the vascular system during vessel growth and organization. We identified a novel junctional adhesion molecule, named JAM-2, by a selective RNA display method, which allowed identification of transcripts encoding(More)
Focal adhesions (FAs) regulate cell migration. Vinculin, with its many potential binding partners, can interconnect signals in FAs. Despite the well-characterized structure of vinculin, the molecular mechanisms underlying its action have remained unclear. Here, using vinculin mutants, we separate the vinculin head and tail regions into distinct functional(More)
Integrins are cell-substrate adhesion molecules that provide the essential link between the actin cytoskeleton and the extracellular matrix during cell migration. We have analyzed alphaVbeta3-integrin dynamics in migrating cells using a green fluorescent protein-tagged beta3-integrin chain. At the cell front, adhesion sites containing alphaVbeta3-integrin(More)
Cell migration in wound healing and disease is critically dependent on integration with the extracellular matrix, but the receptors that couple matrix topography to migratory behavior remain obscure. Using nano-engineered fibronectin surfaces and cell-derived matrices, we identify syndecan-4 as a key signaling receptor determining directional migration. In(More)
The formin-homology protein Dia1 is a target of RhoA and a potent activator of nucleation and elongation of actin filaments. Here, we demonstrate that short-hairpin (sh) RNA-mediated downregulation of Dia1 in human MCF7 epithelial cells disrupts adherens junctions, as manifested by the significantly decreased localization of E-cadherin and associated(More)
Initial integrin-mediated cell-matrix adhesions (focal complexes) appear underneath the lamellipodia, in the regions of the "fast" centripetal flow driven by actin polymerization. Once formed, these adhesions convert the flow behind them into a "slow", myosin II-driven mode. Some focal complexes then turn into elongated focal adhesions (FAs) associated with(More)
Microscopy-based fluorescence resonance energy transfer (FRET) provides an opportunity to monitor molecular processes in the natural environment in live cells. Here we studied molecular interactions and tyrosine phosphorylation of paxillin, Crk-associated substrate (CAS), and focal adhesion kinase (FAK) in focal adhesions. For that purpose, these focal(More)
The correct outgrowth of axons is essential for the development and regeneration of nervous systems. Axon growth is primarily driven by microtubules. Key regulators of microtubules in this context are the spectraplakins, a family of evolutionarily conserved actin-microtubule linkers. Loss of function of the mouse spectraplakin ACF7 or of its close(More)