biosights

Rok keeps its finger on the pulse of apical constriction

Early in Drosophila embryogenesis, contractile pulses of myosin assembly and disassembly constrict the apical domains of a group of epithelial cells to drive their invagination into a ventral furrow. Vasquez et al. reveal that Rho kinase and myosin phosphatase dynamically regulate these myosin pulses and that the stepwise constriction resulting from this helps maintain tissue integrity during epithelial invagination. This biosights episode presents the paper by Vasquez et al. from the August 4, 2014, issue of The Journal of Cell Biology and includes an interview with two of the paper's authors, Claudia Vasquez and Adam Martin (Massachusetts Institute of Technology, Cambridge, MA). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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The fluid dynamics of collective cell migration

During development and tumor metastasis, cells prepare to migrate by undergoing an epithelial-to-mesenchymal transition that loosens their connections to neighboring cells. But some cell types then migrate en masse to their final destinations, indicating that their intercellular adhesions aren't disrupted completely. Kuriyama et al. reveal that the phospholipid lysophosphatidic acid promotes the collective migration of Xenopus neural crest cells by downregulating the surface expression of N-cadherin, granting the cells fluid-like properties that enhance their movement through embryonic tissues. This biosights episode presents the paper by Kuriyama et al. from the July 7, 2014, issue of The Journal of Cell Biology and includes an interview with senior author Roberto Mayor (University College London, UK). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Rab18 tilts the balance of ER structure

The endoplasmic reticulum consists of peripheral tubular networks connected to sheet-like domains surrounding the nucleus. Gerondopoulos et al. reveal that the Rab3GAP complex, which is mutated in the neurodevelopmental disorder Warburg Micro Syndrome, is a guanine nucleotide exchange factor that activates the small GTPase Rab18 (also mutated in Warburg Micro Syndrome) to control the balance between ER tubules and sheets. This biosights episode presents the paper by Gerondopoulos et al. from the June 9, 2014, issue of The Journal of Cell Biology and includes an interview with senior author Francis Barr (University of Oxford, UK). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Phosphoinositides get cells in shape

Early Drosophila embryos undergo 13 rounds of rapid nuclear division before enclosing each nucleus into an individual, membrane-bound cell. Reversi et al. describe how the phosphoinositides PI(4,5)P2 and PI(3,4,5)P3 control the resulting cell shapes by coordinating actomyosin contractility with plasma membrane expansion. This biosights episode presents the paper by Reversi et al. from the May 12, 2014, issue of The Journal of Cell Biology and includes an interview with senior author Stefano De Renzis (EMBL, Heidelberg, Germany). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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An actin lever flattens out the cell

The lamella is a broad, flat region that forms at the front of migrating cells and adheres to the underlying substrate. Burnette et al. reveal that cells flatten out the lamella by mechanically coupling a contractile actomyosin network at the dorsal surface to ventral cell adhesions. This biosights episode presents the paper by Burnette et al. from the April 14, 2014, issue of The Journal of Cell Biology and includes an interview with authors Dylan Burnette (Vanderbilt University School of Medicine, Nashville, TN) and Jennifer Lippincott-Schwartz (NICHD, Bethesda, MD). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Blebs lead the way in Dictyostelium chemotaxis

Membrane blebs can help the leading edge of migrating cells protrude forwards, but the contribution of blebs to the motility of Dictyostelium cells is unclear. Zatulovskiy et al. reveal that blebs form at the front of chemotaxing Dictyostelium cells, particularly when the cells are faced with a mechanically resistant environment, and that this process is guided by a PI3-kinase-dependent signaling pathway. This biosights episode presents the paper by Zatulovskiy et al. from the March 17, 2014, issue of The Journal of Cell Biology and includes an interview with senior author Robert Kay (MRC Laboratory of Molecular Biology, Cambridge, UK). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Shroom takes embryos to new dimensions

During development, the planar polarized distribution of Rho kinase and Myosin II helps Drosophila germ-band cells intercalate so that the embryo extends along its anterior-posterior axis. Simões et al. reveal how Rho GTPase and the actin-binding protein Shroom combine to regulate the localization of Rho kinase and actomyosin contractility during axis elongation. This biosights episode presents the paper by Simões et al. from the February 17, 2014, issue of The Journal of Cell Biology and includes an interview with first author Sérgio de Matos Simões (formerly at Memorial Sloan Kettering Cancer Center, New York and currently at the University of Toronto). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Motors give a new twist to platelet activation

The discoid shape of resting platelets is maintained by a peripheral ring of bundled microtubules called the marginal band. Diagouraga et al. reveal that, upon platelet activation, the motor protein dynein slides microtubules apart, inducing marginal band coiling and the conversion of platelets to a spherical shape. This biosights episode presents the paper by Diagouraga et al. from the January 20, 2014, issue of The Journal of Cell Biology and includes an interview with senior author Karin Sadoul (Institut Albert Bonniot, Grenoble, France). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Tumor cells invade through extracellular matrices by forming actin-rich structures called invadopodia, which contain the transmembrane matrix metalloproteinase MT1-MMP. Monteiro et al. reveal that the Arp2/3 activating protein WASH works with the exocyst complex to deliver MT1-MMP from late endosomes to the invadopodial plasma membrane. This biosights episode presents the paper by Monteiro et al. from the December 23, 2013, issue of The Journal of Cell Biology and includes an interview with senior author Philippe Chavrier (Institut Curie, Paris, France). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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Caspases work as branch managers

When a growing axon nears its target, it arborizes, or branches, to form numerous synaptic connections. Campbell and Okamoto reveal that localized caspase activation downstream of Slit-Robo signaling promotes arbor dynamics and restricts arbor growth. This biosights episode presents the paper by Campbell and Okamoto from the November 25, 2013, issue of The Journal of Cell Biology and includes an interview with lead author Douglas Campbell (formerly at the RIKEN Brain Science Institute, Japan, and currently at the Max Planck Institute for Brain Research, Germany). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research.

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The Rockefeller University Press [email protected]