Issues

G protein–coupled receptor recycling pathways allow cells to modulate downstream signaling.

Spector’s work focuses on the spatial organization and regulation of gene expression.

GPCRs can activate different programs of gene expression from the plasma membrane and the endosome. Bowman et al. show that signaling by endosomal β-2 adrenergic receptors occurs at the microdomains that GPCRs use for sequence-dependent recycling.

Mutations of the endothelial BMP9/10 receptors Alk1 and endoglin are associated with vascular malformations in hereditary hemorrhagic telangiectasia (HHT). Baeyens et al. report that fluid flow potentiates BMP activation of Alk1 signaling to stabilize blood vessels. HHT lesions thus result from a defect in a synergistic mechanical/biochemical signaling pathway.

Paraspeckles are nuclear bodies built on the long noncoding RNA Neat1. Using structural illumination microscopy, West et al. analyze the organization of paraspeckles at the submicron scale and show that paraspeckle proteins are arranged around bundles of Neat1, forming core-shell spheroidal structures dependent on the RNA binding protein Fus.

Using superresolution and quantitative fluorescence microscopy, Das et al. have revealed that iron-transferrin–containing endosomes directly interact with mitochondria, facilitating iron transfer in epithelial cells. Their findings further enrich the repertoire of organelle–organelle direct interactions to accomplish a functional significance.

Kasula et al. use single-molecule imaging to reveal the diffusional signature for the SNARE proteins Munc18-1 and syntaxin-1A during secretory vesicle priming. The authors show that a conformational change in the Munc18-1 domain 3a hinge-loop regulates engagement of syntaxin-1A in the SNARE complex.

p190RhoGAP (p190A) is a negative regulator of RhoA and localizes to membrane protrusions, where its GAP activity is required for directional migration. Here, Binamé et al. identify the protrusion-localization sequence in p190A and show that cancer-associated mutations in this region affect p190A localization and function as well as tumor cell migration.

Ciliary transition zone (TZ) assembly is complex and incompletely understood. Vieillard et al. show that Drosophila Cby and Dila cooperate to assemble the TZ and membrane cap, which, together with microtubule remodeling by kinesin-13, is required for axoneme formation in male germ cells.