biosights: January 21, 2013 - How cell shape changes unfold

submitted by: JCB
Under certain conditions, cells form protrusions that oscillate rapidly around the cell periphery. Kapustina et al. reveal that these oscillatory protrusions, which may be related to processes involved in amoeboid cell migration, are driven by the cyclic folding and unfolding of the plasma membrane and its underlying actin cortex. This biosights episode presents the paper by Kapustina et al. from the January 7, 2013, issue of The Journal of Cell Biology and includes an interview with lead...

biosights: Decemeber 24, 2012 - Global sourcing for cytokinetic ring assembly

submitted by: JCB
At the end of cytokinesis, the microtubule-rich midbody connecting the daughter cells is either shed into the extracellular space or retained by one of the daughters. Chai et al. find that the midbodies released from C. elegans Q neuroblasts are cleared via a pathway that closely mimics the removal of apoptotic cell corpses. This biosights episode presents the paper by Chai et al. from the December 24, 2012 issue of The Journal of Cell Biology and includes an interview with senior author...

biosights: November 26, 2012 - Global sourcing for cytokinetic ring assembly

submitted by: JCB
Fission yeast are thought to assemble their cytokinetic actomyosin rings from actin filaments nucleated at myosin-containing nodes around the cell equator. Using an improved actin-binding probe, Huang et al. find that actin cables are nucleated all over the cortex of mitotic fission yeast and are transported to the division site for incorporation into the contractile ring. This biosights episode presents the paper by Huang et al. from the November 26, 2012, issue of The Journal of Cell...

biosights: October 29, 2012 - A stiff test for collectively migrating cells

submitted by: JCB
The mechanical properties of the extracellular matrix are known to regulate the migration of single cells, but whether substrate stiffness also affects collective cell migration is unclear. Ng et al. reveal that epithelial sheets move faster on stiffer matrices due to increased myosin contractility and mechanical coupling through cell-cell adhesions. This biosights episode presents the paper by Ng et al. from the October 29, 2012, issue of The Journal of Cell Biology and includes an...

biosights: October 1, 2012 - Cortical dynein puts the spindle in its place

submitted by: JCB
The position of the mitotic spindle is controlled by the microtubule-based motor dynein and a ternary complex of the proteins NuMA, LGN, and Ga. Kotak et al. demonstrate that the ternary complex's primary function is to localize dynein to the cell cortex and that cortical dynein is sufficient to position the mitotic spindle in HeLa cells. This biosights episode presents the paper by Kotak et al. from the October 1, 2012, issue of The Journal of Cell Biology and includes an interview with...

biosights: August 6, 2012 - Redistribution aids the pore

submitted by: JCB
In animal cells, the nuclear lamina keeps nuclear pore complexes evenly distributed throughout the nuclear envelope. Steinberg et al. reveal that fungi, which lack nuclear laminae, prevent their nuclear pores from clustering by moving them around on cytoskeletal tracks, a process that also helps to organize fungal chromosomes and optimize nucleocytoplasmic transport. This biosights episode presents the paper by Steinberg et al. from the August 6, 2012, issue of The Journal of Cell Biology...

Asters help embryonic nuclei find their own space

submitted by: JCB
In early Drosophila embryos, nuclei undergo rapid, synchronous divisions without being separated into individual cells by cytokinesis. Telley et al. develop a cell-free assay to reveal that microtubule asters help disperse the nuclei throughout the embryonic cytoplasm, moving them to the right position for development to continue. This biosights episode presents the paper by Telley et al. from the June 25, 2012, issue of The Journal of Cell Biology and includes an interview with lead author...

T cell signaling goes with the flow

submitted by: JCB
Activated T cell receptors stimulate actin polymerization at the periphery of the immunological synapses that form between lymphocytes and antigen-presenting cells. Babich et al. reveal that the retrograde flow of actin, largely driven by continuous polymerization, is required to sustain downstream signaling events and T cell activation. This biosights episode presents the paper by Babich et al. from the June 11, 2012 issue of The Journal of Cell Biology and includes an interview with senior...

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...