biosights: May 13, 2013 - Ventral lamellipodia plug the gaps

submitted by: JCB
When leukocytes enter or exit the blood stream, they leave small wounds both in and between the vascular endothelial cells, which must be quickly repaired so that the endothelium can maintain its barrier function. Martinelli et al. reveal that wounding causes a loss of tension in endothelial cells, inducing the formation of ventral lamellipodia that close the holes left by transmigrating leukocytes. This biosights episode presents the paper by Martinelli et al. from the April 29, 2013, issue...

biosights: April 15, 2013 - Frog oocytes evade the checkpoint

submitted by: JCB
Most dividing cells possess a spindle assembly checkpoint that prevents them from entering anaphase until all their chromosomes are correctly attached to the metaphase spindle. Shao et al. reveal that Xenopus eggs lack this checkpoint, allowing them to undergo meiosis in the absence of microtubules or in the presence of monopolar spindles. This biosights episode presents the paper by Shao et al. from the April 15, 2013 issue of The Journal of Cell Biology and includes an interview with...

biosights: March 18, 2013 - Breaking egg symmetry

submitted by: JCB
During the first meiotic division of mammalian oocytes, the meiotic spindle and chromosomes move from the interior to the periphery of the cell. Yi et al. reveal that chromosome migration occurs in two sequential phases driven by the actin nucleators Fmn2 and the Arp2/3 complex. This biosights episode presents the paper by Yi et al. from the March 4, 2013, issue of The Journal of Cell Biology and includes an interview with senior author Rong Li (Stowers Institute for Medical Research, Kansas...

biosights: February 18, 2013 - Erecting a myosin scaffold for cytokinesis

submitted by: JCB
Cell division requires the coordinated action of proteins that promote actomyosin contraction, membrane trafficking, and extracellular matrix remodeling. Wloka et al. reveal that, in budding yeast, the type II myosin Myo1 acts as an immobile scaffold at the bud neck to organize proteins involved in forming the primary septum during cytokinesis. This biosights episode presents the paper by Wloka et al. from the February 4, 2013, issue of The Journal of Cell Biology and includes an interview...

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...