biosights

Retinal ganglion cells have a backup plan

Retinal ganglion cells (RGCs) are born at the apical side of the retinal neuroepithelium before they translocate to the basal side and send out axons to form the optic nerve. Icha et al. reveal that, in the zebrafish retina, RGC translocation is expedited by basal process attachment and a population of stable microtubules. If necessary, however, RGCs can switch to a backup, multipolar migratory mode to ensure that they reach the basal lamina in time to support the later stages of retinal development. This biosights episode presents the paper by Icha et al. from the October 24th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper’s senior author, Caren Norden (Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 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 iron hand controls endosome-mitochondria contacts

In erythroid cells, endocytosed iron is directly transferred into mitochondria at dynamic endosome-mitochondria contacts. Das et al. reveal that this process also occurs in epithelial cells, and that the motility of endosomes, and the duration of their interactions with mitochondria, is modulated by intra-endosomal iron release from transferrin. This biosights episode presents the paper by Das et al. from the September 26th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper’s senior author, Margarida Barroso (Albany Medical College, Albany, NY). 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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After they are formed by the closure of membrane ruffles, macropinosomes mature by fusing with each other and with endosomes, before eventually delivering their fluid phase cargo to lysosomes. Dolat and Spiliotis reveal that septin filaments promote macropinosome maturation and lysosomal delivery by facilitating macropinosome/endosome fusion. This biosights episode presents the paper by Dolat and Spiliotis from the August 29th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Elias Spiliotis (Drexel University, Philadelphia, PA). 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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Fibroblasts initiate ciliogenesis inside the cell, but polarized epithelial cells form a primary cilium at the apical cell surface through a mechanism that is largely uncharacterized. Bernabé-Rubio et al. reveal that, in polarized MDCK cells, a remnant of the cytokinetic midbody moves to the center of the apical surface, where it encounters the centrosome and enables cilium formation. This biosights episode presents the paper by Bernabé-Rubio et al. from the August 1, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Miguel Alonso (Universidad Autónoma de Madrid, Spain). 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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In mature neurons, the axonal transport of mitochondria is suppressed by the expression of the mitochondrial anchoring protein syntaphilin. Zhou et al. reveal that enhancing mitochondrial transport in mature neurons rescues energy deficits and facilitates axon regeneration after injury. This biosights episode presents the paper by Zhou et al. from the July 4th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Zu-Hang Sheng (National Institute of Neurological Disorders and Stroke, 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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Spatial confinement enhances collective cell migration in vitro, but whether it promotes collective migration in vivo is unclear. Szabó et al. reveal that the extracellular matrix protein versican confines neural crest cells to enhance their collective migration during Xenopus laevis embryogenesis. This biosights episode presents the paper by Szabó et al. from the June 6th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Roberto Mayor (University College London, London, England, 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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Exosomes are small, extracellular vesicles that transfer lipid, protein, and RNA cargoes between cells, but relatively little is known about how they are taken up and processed by their target cells. Heusermann et al. reveal that exosomes "surf" along recipient cell filopodia before being efficiently endocytosed and targeted to the endoplasmic reticulum. This biosights episode presents the paper by Heusermann et al. from the April 25, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Nicole Meisner-Kober (Novartis Institutes for Biomedical Research, Basel, Switzerland). 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 plasma membrane phosphoinositide PI(4,5)P₂ is derived from PI(4)P, whose levels are controlled by the essential lipid phosphatase Sac1. Sac1 is an integral ER membrane protein, but Dickson et al. reveal that it localizes to dynamic ER–plasma membrane contact sites to regulate plasma membrane PI(4)P and PI(4,5)P₂ levels. This biosights episode presents the paper by Dickson et al. from the April 11th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's corresponding author, Eamonn Dickson (University of Washington School of Medicine, Seattle, WA). 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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During Drosophila oogenesis, the collective migration of egg chamber follicle cells drives the chambers' rotation and elongation. Squarr et al. reveal that the atypical cadherin Fat2 recruits the WAVE regulatory complex to tricellular junctions to induce the formation of whip-like actin protrusions that control collective migration and tissue rotation. This biosights episode presents the paper by Squarr et al. from the February 29th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Sven Bogdan (University of Münster, Münster, 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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Though stem cells transplanted into heart attack patients can develop into cardiomyocytes and integrate with undamaged host tissue, preclinical studies and clinical trials have only shown limited improvements in cardiac function. Using a simplified, in vitro, "muscle on-a-chip" system, Aratyn-Schaus et al. reveal that mechanical forces aren't transmitted efficiently between weaker, stem cell–derived cardiomyocytes and stronger, more mature host cells. This biosights episode presents the paper by Aratyn-Schaus et al. from the February 15th, 2016, issue of The Journal of Cell Biology and includes an interview with one of the paper's co-first authors, Francesco Pasqualini (Harvard University, 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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P-cadherin provides the driving force for collective cell migration

Collective cell migration is an important process in normal development, wound repair, and tumor metastasis. Plutoni et al. reveal that the cell adhesion molecule P-cadherin promotes collective cell migration via the small GTPase Cdc42, inducing cell polarization and increasing the strength and orientation of mechanical forces. This biosights episode presents the paper by Plutoni et al. from the January 18th, 2016, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Cécile Gauthier-Rouvière (Centre de Recherche de Biochimie Macromoléculaire, Centre National de la Recherche Scientifique, Montpellier, 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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How catastrophes help oocytes avoid disaster

During meiosis, oocytes must attach homologous chromosomes to opposite spindle poles, but the cells take several hours to assemble a bipolar spindle. Gluszek et al. reveal that, in Drosophila oocytes, the microtubule catastrophe–promoting protein Sentin delays the formation of stable kinetochore–microtubule attachments until spindle assembly is complete, thereby preventing homologous chromosomes from incorrectly attaching to the same spindle pole. This biosights episode presents the paper by Głuszek et al. from the December 21st, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Hiroyuki Ohkura (University of Edinburgh, Edinburgh, Scotland, 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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Cells migrate on the crest of a wave

Cells move through complex 3D environments in vivo, but studying 3D modes of migration in vitro remains a major challenge. Guetta-Terrier et al. examine the movement of cells along suspended nanofibers that mimic 3D fibrillar matrices and find that their migration is guided by fin-like protrusions that propagate away from the cell body to extend the leading edge. This biosights episode presents the paper by Guetta-Terrier et al. from the November 9th, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's corresponding authors, Benoit Ladoux (National University of Singapore and Institut Jacques Monod, Paris, France) and Nils Gauthier (National University of Singapore). 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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CLIP-170 tips its hand in viral transport

After entering a cell, many viruses move toward the nucleus by binding to the microtubule-based motor protein dynein. Jovasevic et al. reveal, however, that herpes simplex virus must first associate with the plus ends of microtubules in a process that requires the dynein accessory factor dynactin and the plus end tracking proteins EB1 and CLIP-170. This biosights episode presents the paper by Jovasevic et al. from the October 26th, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's corresponding author, Derek Walsh (Northwestern University, Chicago, IL). 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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Maintaining the link between spindle and furrow position

The cytokinetic cleavage furrow must be carefully aligned with the spindle midzone during asymmetric cell division. Pacquelet et al. discover a pathway that maintains the connection between spindle and furrow position in one-cell C. elegans embryos by inhibiting the accumulation of myosin at the anterior cortex during cytokinesis. This biosights episode presents the paper by Pacquelet et al. from the September 28, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's corresponding author, Anne Pacquelet (Centre National de la Recherche Scientifique and Institut de Génétique et Développement de Rennes, 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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Pushing the envelope on spindle assembly

During mitosis, numerous proteins accumulate around the mitotic spindle to help it assemble and segregate sister chromatids correctly. Schweizer et al. reveal that a membranous spindle envelope facilitates the accumulation of these proteins by excluding large organelles from the spindle region. This biosights episode presents the paper by Schweizer et al. from the August 31st, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Helder Maiato (University of Porto, Porto, Portugal). 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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Endocytosis brings closure to epithelial wounds

Epithelial cells bordering a wound respond by forming two types of actin-based structure: dynamic membrane protrusions that help the cells crawl into the wound and/or seal it and an actomyosin cable that encircles the wound and closes it like a purse string. Matsubayashi et al. reveal that the endocytic remodeling of intercellular adherens junctions promotes Drosophila epidermal wound healing by coordinating the activity of multiple actin regulators at the wound edge. This biosights episode presents the paper by Matsubayashi et al. from the August 3rd, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Tom Millard (University of Manchester, Manchester, 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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Interphase centrosomes flare up

Centrosomes undergo dramatic changes in size and structure during the rapid cell cycles of early Drosophila embryos. Lerit et al. reveal that a scaffold formed by the proteins centrosomin and PLP is required to maintain the activity of interphase centrosomes, which is essential for nuclear spacing and proper chromosome segregation. This biosights episode presents the paper by Lerit et al. from the July 6th, 2015, issue of The Journal of Cell Biology and includes an interview with two of the paper's authors, Dorothy Lerit and Nasser Rusan (National Heart, Lung, and Blood Institute, 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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Melanosomal cargoes BLOC'd off from alternate routes

The BLOC-2 complex contains three subunits encoded by genes mutated in Hermansky-Pudlak syndrome, a disease caused by defects in the trafficking pathways that form melanosomes and other lysosome-related organelles. Dennis et al. reveal that the BLOC-2 complex promotes the delivery of melanosomal cargo by targeting recycling endosomal tubules to maturing melanosomes. This biosights episode presents the paper by Dennis et al. from the May 25, 2015, issue of The Journal of Cell Biology and includes an interview with one of the paper's senior authors, Michael Marks (University of Pennsylvania, Philadelphia, PA). 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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Formin' actin at adherens junctions

Actin assembly promotes the formation of intercellular adherens junctions, but the role of actin-nucleating formin proteins in this process remains unclear. Grikscheit et al. reveal that, in breast epithelial cells cultured in 3D, the formin FMNL2 stimulates junctional actin assembly downstream of the small GTPase Rac1. This biosights episode presents the paper by Grikscheit et al. from the May 11, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Robert Grosse (University of Marburg, Marburg, 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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