Torsten Wittmann

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TPX2, the targeting protein for Xenopus kinesin-like protein 2 (Xklp2), was identified as a microtubule-associated protein that mediates the binding of the COOH-terminal domain of Xklp2 to microtubules (Wittmann, T., H. Boleti, C. Antony, E. Karsenti, and I. Vernos. 1998. J. Cell Biol. 143:673-685). Here, we report the cloning and functional(More)
Polarity of the microtubule (MT) cytoskeleton is essential for many cell functions. Cytoplasmic linker-associated proteins (CLASPs) are MT-associated proteins thought to organize intracellular MTs and display a unique spatiotemporal regulation. In migrating epithelial cells, CLASPs track MT plus ends in the cell body but bind along MTs in the lamella. In(More)
TPX2 has multiple functions during mitosis, including microtubule nucleation around the chromosomes and the targeting of Xklp2 and Aurora A to the spindle. We have performed a detailed domain functional analysis of TPX2 and found that a large N-terminal domain containing the Aurora A binding peptide interacts directly with and nucleates microtubules in pure(More)
It has long been known that microtubule depletion causes axons to retract in a microfilament-dependent manner, although it was not known whether these effects are the result of motor-generated forces on these cytoskeletal elements. Here we show that inhibition of the motor activity of cytoplasmic dynein causes the axon to retract in the presence of(More)
Xklp2 is a plus end-directed Xenopus kinesin-like protein localized at spindle poles and required for centrosome separation during spindle assembly in Xenopus egg extracts. A glutathione-S-transferase fusion protein containing the COOH-terminal domain of Xklp2 (GST-Xklp2-Tail) was previously found to localize to spindle poles (Boleti, H., E. Karsenti, and(More)
Actin in migrating cells is regulated by Rho GTPases. However, Rho proteins might also affect microtubules (MTs). Here, we used time-lapse microscopy of PtK1 cells to examine MT regulation downstream of Rac1. In these cells, "pioneer" MTs growing into leading-edge protrusions exhibited a decreased catastrophe frequency and an increased time in growth as(More)
In all eukaryotes, a microtubule-based structure known as the spindle is responsible for accurate chromosome segregation during cell division. Spindle assembly and function require localized regulation of microtubule dynamics and the activity of a variety of microtubule-based motor proteins. Recent work has begun to uncover the molecular mechanisms that(More)
In the leading edge of migrating cells, a subset of microtubules exhibits net growth in a Rac1- and p21-activated kinase-dependent manner. Here, we explore the possibility of whether phosphorylation and inactivation of the microtubule-destabilizing protein Op18/stathmin could be a mechanism regulating microtubule dynamics downstream of Rac1 and(More)
Remodeling of actin filaments is necessary for epithelial-mesenchymal transition (EMT); however, understanding of how this is regulated in real time is limited. We used an actin filament reporter and high-resolution live-cell imaging to analyze the regulated dynamics of actin filaments during transforming growth factor-β-induced EMT of mammary epithelial(More)
Proteins that in cells specifically bind to growing microtubule plus ends (+TIPs) are thought to play important roles in polarization of the cytoskeleton. However, most +TIPs do not show a bias of their microtubule-binding behavior toward different subcellular regions. Here, we examine the dynamics of the +TIP CLASP in migrating PtK1 epithelial cells. We(More)