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He L.,Harvard University | Montell D.,Center for Cell Dynamics
Nature Cell Biology | Year: 2012

How cells sense and respond to physical forces is an area of intense investigation, which poses significant challenges for in vitro experiments and even greater obstacles for in vivo studies. Analyses of integrin complex dynamics in Drosophila melanogaster now provide evidence that altering mechanical force modulates the stability of integrin adhesion in vivo. © 2012 Macmillan Publishers Limited. All rights reserved.

Rankin K.E.,University of Washington | Rankin K.E.,Bernhard Nocht Institute for Tropical Medicine | Wordeman L.,University of Washington | Wordeman L.,Center for Cell Dynamics
Journal of Cell Biology | Year: 2010

Astral microtubules (MTs) are known to be important for cleavage furrow induction and spindle positioning, and loss of astral MTs has been reported to increase cortical contractility. To investigate the effect of excess astral MT activity, we depleted the MT depolymerizer mitotic centromere-associated kinesin (MCAK) from HeLa cells to produce ultra-long, astral MTs during mitosis. MCAK depletion promoted dramatic spindle rocking in early anaphase, wherein the entire mitotic spindle oscillated along the spindle axis from one proto-daughter cell to the other, driven by oscillations of cortical nonmuscle myosin II. The effect was phenocopied by taxol treatment. Live imaging revealed that cortical actin partially vacates the polar cortex in favor of the equatorial cortex during anaphase. We propose that this renders the polar actin cortex vulnerable to rupture during normal contractile activity and that long astral MTs enlarge the blebs. Excessively large blebs displace mitotic spindle position by cytoplasmic flow, triggering the oscillations as the blebs resolve. © 2010 Rankin and Wordeman.

Komatsu T.,Center for Cell Dynamics | Kukelyansky I.,Center for Cell Dynamics | McCaffery J.M.,Johns Hopkins University | Ueno T.,Center for Cell Dynamics | And 2 more authors.
Nature Methods | Year: 2010

Using new chemically inducible dimerization probes, we generated a system to rapidly target proteins to individual intracellular organelles. Using this system, we activated Ras GTPase at distinct intracellular locations and induced tethering of membranes from two organelles, endoplasmic reticulum and mitochondria. Innovative techniques to rapidly perturb molecular activities and organelle-organelle communications at precise locations and timing will provide powerful strategies to dissect spatiotemporally complex biological processes. © 2010 Nature America, Inc. All rights reserved.

Guo Q.,Wilmer Eye Institute | Wang X.,Center for Cell Dynamics | Tibbitt M.W.,Howard Hughes Medical Institute | Anseth K.S.,Howard Hughes Medical Institute | And 2 more authors.
Biomaterials | Year: 2012

Synthetic extracellular matrices provide a framework in which cells can be exposed to defined physical and biological cues. However no method exists to manipulate single cells within these matrices. It is desirable to develop such methods in order to understand fundamental principles of cell migration and define conditions that support or inhibit cell movement within these matrices. Here, we present a strategy for manipulating individual mammalian stem cells in defined synthetic hydrogels through selective optical activation of Rac, which is an intracellular signaling protein that plays a key role in cell migration. Photoactivated cell migration in synthetic hydrogels depended on mechanical and biological cues in the biomaterial. Real-time hydrogel photodegradation was employed to create geometrically defined channels and spaces in which cells could be photoactivated to migrate. Cell migration speed was significantly higher in the photo-etched channels and cells could easily change direction of movement compared to the bulk hydrogels. © 2012 Elsevier Ltd.

Montell D.J.,Center for Cell Dynamics | Yoon W.H.,Center for Cell Dynamics | Yoon W.H.,Howard Hughes Medical Institute | Starz-Gaiano M.,University of Maryland Baltimore County
Nature Reviews Molecular Cell Biology | Year: 2012

Cell movements are essential for animal development and homeostasis but also contribute to disease. Moving cells typically extend protrusions towards a chemoattractant, adhere to the substrate, contract and detach at the rear. It is less clear how cells that migrate in interconnected groups in vivo coordinate their behaviour and navigate through natural environments. The border cells of the Drosophila melanogaster ovary have emerged as an excellent model for the study of collective cell movement, aided by innovative genetic, live imaging, and photomanipulation techniques. Here we provide an overview of the molecular choreography of border cells and its more general implications. © 2012 Macmillan Publishers Limited. All rights reserved.

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