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 ...
Jan 18, 2016•8 min
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. Thi...
Dec 21, 2015•7 min
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, i...
Nov 23, 2015•8 min
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 Jou...
Oct 26, 2015•7 min
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 Journa...
Sep 28, 2015•8 min
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 p...
Aug 31, 2015•6 min
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 regulator...
Aug 03, 2015•8 min
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 a...
Jul 06, 2015•9 min
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, 20...
Jun 08, 2015•6 min
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 int...
May 11, 2015•7 min
A motif that helps myosin II-B lead from behind Myosin II-A and myosin II-B play distinct roles in establishing the front–back polarity of migrating mesenchymal cells. Juanes-Garcia et al. identify a short, serine-rich motif in the non-helical tail domain of myosin II-B that enables this isoform to form stable actomyosin bundles that define the cell rear. This biosights episode presents the paper by Juanes-Garcia et al. from the April 13, 2015, issue of The Journal of Cell Biology and includes a...
Apr 13, 2015•6 min
PAPC separates tissues at a Snail's pace Brachet's cleft separates the ectoderm and mesoderm of early Xenopus and zebrafish embryos. Luu et al. reveal that, in conjunction with the transcription factor Snail1, the protocadherin PAPC promotes tissue separation by down-regulating planar cell polarity proteins at the ectoderm-mesoderm boundary. This biosights episode presents the paper by Luu et al. from the March 16, 2015, issue of The Journal of Cell Biology and includes an interview with one of ...
Mar 16, 2015•8 min
Filopodia point the way for haptotaxis Migrating fibroblasts maintain or change their direction by branching off new lamellipodia from existing protrusions at the cell's leading edge. Johnson et al. reveal that filopodial protrusions initiate and orient these lamellipodia, helping fibroblasts navigate gradients of immobilized guidance cues. This biosights episode presents the paper by Johnson et al. from the February 16, 2015, issue of The Journal of Cell Biology and includes an interview with t...
Feb 16, 2015•7 min
Tubulin transport pumps up cilia The assembly of cilia and flagella requires the delivery of large amounts of tubulin to the growing ends of the organelles' microtubules. Craft et al. reveal that tubulin loading onto intraflagellar transport particles is specifically upregulated in growing cilia. This biosights episode presents the paper by Craft et al. from the January 19, 2015, issue of The Journal of Cell Biology and includes an interview with the paper's senior author, Karl Lechtreck (Univer...
Jan 19, 2015•7 min
Osmotic gradient is just the tonic for wounded epithelia Rapid wound repair is generally thought to be initiated by intrinsic cues, such as changes in the structure or mechanics of damaged tissues. Gault et al. reveal that an extrinsic signal — the osmolarity of the external environment — can stimulate wound closure in zebrafish by inducing epithelial cell migration. This biosights episode presents the paper by Gault et al. from the December 22, 2014, issue of The Journal of Cell Biology and inc...
Dec 22, 2014•7 min
Dynein helps centrioles stick together Dynein has numerous functions in mitosis, but the function of the motor complex's light intermediate chains is poorly understood. Jones et al. reveal that dynein's light intermediate chains are required to maintain centrosome integrity during mitosis, preventing the premature separation of mother-daughter centrioles and the formation of multipolar spindles. This biosights episode presents the paper by Jones et al. from the November 24, 2014, issue of The Jo...
Nov 24, 2014•9 min
Cdc42 prompts a change of heart The apical surfaces of polarized epithelia are covered by short, actin-rich protrusions called microvilli, but what happens to these structures when cells detach from a monolayer during development or disease is unclear. Klingner et al. reveal that non-confluent epithelial cells form longer, more dynamic microvilli on their apical surface that connect to a cortical actomyosin network. This biosights episode presents the paper by Klingner et al. from the October 13...
Oct 27, 2014•7 min
Cdc42 prompts a change of heart The Drosophila heart is a simple tubular structure with a central lumen. Vogler et al. reveal that the small GTPase Cdc42 and actin-nucleating formin proteins promote lumen formation by regulating the dynamics of non-muscle myosin in cardioblasts during heart morphogenesis. This biosights episode presents the paper by Vogler et al. from the September 29, 2014, issue of The Journal of Cell Biology and includes an interview with two of the paper's authors, Georg Vog...
Sep 29, 2014•8 min
Deploying exosomes in a battle of the sexes The paired accessory glands of male Drosophila secrete multiple signaling factors into the seminal fluid that promote reproductive success by altering the recipient female's physiology and behavior. This biosights episode presents the paper by Corrigan et al. from the September 1, 2014, issue of The Journal of Cell Biology and includes an interview with corresponding author Alexander Bershadsky (Weizmann Institute, Israel, and Mechanobiology Institute,...
Sep 01, 2014•9 min
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...
Aug 04, 2014•8 min
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...
Jul 07, 2014•8 min
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 th...
Jun 09, 2014•7 min
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 inte...
May 12, 2014•9 min
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 (...
Apr 14, 2014•8 min
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...
Mar 17, 2014•9 min
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...
Feb 17, 2014•10 min
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 incl...
Jan 20, 2014•8 min
Tumor cells WASH away the extracellular matrix 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 C...
Dec 23, 2013•8 min
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 B...
Nov 25, 2013•8 min
A framework for understanding muscle microtubules The microtubules of skeletal muscle fibers are arranged into an orthogonal grid, but how this network is formed is unknown. Oddoux et al. reveal that the network is built by dynamic microtubules nucleated from Golgi elements. This biosights episode presents the paper by Oddoux et al. from the October 28, 2013, issue of The Journal of Cell Biology and includes an interview with senior author Evelyn Ralston (NIH, Bethesda, MD). Produced by Caitlin ...
Oct 28, 2013•7 min
