biosights: September 29, 2014 - Cdc42 prompts a change of heart

submitted by: JCB
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 Vogler and Rolf Bodmer...

biosights: September 1, 2014 - Deploying exosomes in a battle of the sexes

submitted by: JCB
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. Corrigan et al. reveal that the secondary cells of accessory glands secrete membrane-bound exosomes in a BMP-dependent manner that, after being transferred into the female reproductive tract, inhibit the female's inclination to re-mate with other male flies. This biosights episode presents the...

biosights: August 4, 2014 - Rok keeps its finger on the pulse of apical constriction

submitted by: JCB
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 presents the paper by Vasquez et al. from the August...

biosights: July 7, 2014 - The fluid dynamics of collective cell migration

submitted by: JCB
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 downregulating the surface expression of...

biosights: June 9, 2014 - Rab18 tilts the balance of ER structure

submitted by: JCB
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 the paper by Gerondopoulos et al. from...

biosights: May 12, 2014 - Phosphoinositides get cells in shape

submitted by: JCB
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 interview with senior author Stefano...

biosights: April 14, 2014 - An actin lever flattens out the cell

submitted by: JCB
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 (Vanderbilt University School of...

biosights: March 17, 2014 - Blebs lead the way in Dictyostelium chemotaxis

submitted by: JCB
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 Zatulovskiy et al. from the March 17,...

biosights: February 17, 2014 - Shroom takes embryos to new dimensions

submitted by: JCB
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. Simoes 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 Simoes et al. from the February 17, 2014, issue of The Journal of Cell Biology and...

biosights: January 20, 2014 - Motors give a new twist to platelet activation

submitted by: JCB
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 includes an interview with senior author Karin...