A new way forward for fibroblasts

submitted by: JCB
Fibroblasts moving across two-dimensional surfaces form lamellipodial protrusions at their leading edge, but how cells move through three-dimensional environments is less well understood. Petrie et al. reveal that, depending on the strength of intracellular RhoA signaling and on the elastic properties of the extracellular matrix, fibroblasts can migrate through 3D environments using either lamellipodia or blunt, cylindrical protrusions called lobopodia. This biosights episode presents the...

PI3K's Pivotal Role in Cell Migration

submitted by: JCB
Phosphoinositide 3-kinase (PI3K) and its phospholipid products are polarized toward the front of migrating fibroblasts, but their exact function in persistent motility remains unclear. Welf et al. reveal that PI3K signaling helps reorient migrating fibroblasts by stabilizing branched protrusions at the leading edge, allowing the cell to pivot and move in a different direction. This biosights episode presents the paper by Welf et al. from the April 2, 2012, issue of The Journal of Cell...

Vinculin minds the endothelial gap

submitted by: JCB
The adhesions between endothelial cells transiently remodel in response to angiogenic growth factors and inflammatory cytokines. Huveneers et al. reveal that remodeling takes place at a subset of adhesions called focal adherens junctions, which recruit the mechanosensory protein Vinculin to resist tension from the actomyosin cytoskeleton and avoid excessive disruption during the remodeling process. This biosights episode presents the paper by Huveneers et al. from the March 5, 2012, issue of...

Neuronal autophagosomes mature on the move

submitted by: JCB
Autophagy is a cellular degradation pathway essential for neuronal survival, but little is known about the dynamics of autophagic organelles in neurons. Maday et al. reveal that autophagosomes form and engulf cargo at the distal tips of neurites and then mature into degradative autolysosomes as they move toward the cell body. This biosights episode presents the paper by Maday et al. from the February 20, 2012, issue of The Journal of Cell Biology and includes an interview with authors Sandra...

Septins rein in the membrane

submitted by: JCB
T cells require the septin family of GTP-binding proteins to maintain the integrity of their plasma membranes as they invade through tissues. Gilden et al. reveal that septins function by assembling on membrane blebs to retract them back into shape. This biosights episode presents the paper by Gilden et al. from the January 9, 2012, issue of The Journal of Cell Biology and includes an interview with senior author Max Krummel (University of California, San Francisco). Produced by Caitlin...

A Twin-Track Approach to Building Desmosomes

submitted by: JCB
Desmosomes are intercellular adhesions whose adhesive core is formed by two distinct classes of cadherin molecules -- desmogleins and desmocollins. Nekrasova et al. reveal that these two cadherins are independently transported to the cell surface by two different kinesin motors. This biosights episode presents the paper by Nekrasova et al. from the December 26, 2011, issue of The Journal of Cell Biology and includes an interview with senior author Kathleen Green (Northwestern University...

CKIδ Decentralizes the Centrosome

submitted by: JCB
When a T cell encounters a target antigen-presenting cell, the lymphocyte's centrosome relocalizes to a specialized contact between the two cells called the immunological synapse. Zyss et al. reveal that casein kinase Iδ helps to reposition the centrosome in activated T cells, perhaps by working with the microtubule plus-end binding protein EB1 to regulate microtubule growth. This biosights episode presents the paper by Zyss et al. from the November 28, 2011, issue of The Journal of Cell...

Cofilin severs the ties between cytokinetic nodes

submitted by: JCB
Cytokinetic nodes are precursor structures that assemble into the actomyosin contractile ring that separates daughter cells in cytokinesis. Chen and Pollard describe how the actin-severing protein cofilin promotes the rapid formation of a complete contractile ring by limiting the actin-based connections between individual nodes. This biosights episode presents the paper by Chen and Pollard from the October 31, 2011, issue of The Journal of Cell Biology, and includes an interview with authors...

Moesin keeps mitotic cells in shape

submitted by: JCB
The ERM protein Moesin helps mitotic cells undergo a series of dramatic shape changes by linking the actin cytoskeleton to the plasma membrane. Roubinet et al. describe how Moesin's localization and activity is regulated over the course of the cell cycle by two different pathways that control Moesin phosphorylation and phosphoinositide synthesis. This biosights episode presents the paper by Roubinet et al. from the October 3, 2011, issue of The Journal of Cell Biology, and includes an...

Actin puts the squeeze on Weibel-Palade bodies

submitted by: JCB
The actin cytoskeleton has been proposed to regulate exocytosis in many different ways. Nightingale et al. use a two-color, live-cell imaging assay to reveal two contrasting functions of actin in distinct stages of Weibel-Palade body secretion: actin-based anchors inhibit the fusion of these secretory granules with the plasma membrane but, post-fusion, a contractile actin ring squeezes granule content out of the cell. This biosights episode presents the paper by Nightingale et al. from the...