- Plastin regulates cortical contractility
Ding et al. characterize the function of the F-actin bundling protein plastin in the Caenorhabditis elegans zygote. They demonstrate that plastin is important for optimal connectivity in the cortical actomyosin network that drives large-scale contractile processes such as polarization and cytokinesis.
- Neuralized regulates Crumbs via Stardust
The E3 ubiquitin ligase Neuralized is shown to interact with a subset of the Stardust isoforms to regulate the endocytosis of the apical protein Crumbs and thereby promote epithelial remodeling during Drosophila development.
- Linking ER–endosome contacts to lysosome function
Hereditary spastic paraplegia (HSP) is a genetically heterogeneous disease caused by mutations in many genes, including those encoding spastin, strumpellin, or REEP1. Allison et al. show that similar lysosomal phenotypes are associated with mutations in different classes of HSP proteins and suggest that defective ER–endosome contacts and endosome tubule fission may be a common cause of axon degeneration in the disease.
- Role of the daughter centriole in ciliogenesis
During ciliogenesis, the daughter centriole is found next to the mother, but its role in this process is not known. Loukil et al. show that a daughter centriole is necessary for primary cilia formation by promoting Neurl-4–dependent removal of the negative ciliogenesis regulator CP110 from the mother.
- Photoreceptor discs form via ectosome retention
Visual signal transduction occurs on the surface of membrane discs stacked inside the ciliary outer segment of photoreceptor cells. Salinas et al. show that discs are formed from ciliary ectosomes whose release is blocked by the protein peripherin/RDS. This explains how photoreceptors transform their primary cilia into the light-sensing outer segment organelle.
- Cell number plasticity by DNTs and Tolls
A three-tier mechanism involving distinct neurotrophin family ligand forms, different Toll receptors, and different adaptors regulates both cell survival and death. This rich mechanism confers cell number plasticity and could underlie structural plasticity in the nervous system and structural integrity, homeostasis, and regeneration in wider contexts.
- Myosin II function in neuroblast ingression
Drosophila neural stem cells, or neuroblasts, ingress from the neuroepithelium in an EMT-like process, during which the apical cell domain is lost. Apical constriction of neuroblasts and the serial loss of cell–cell contacts require periodic pulses of actomyosin that cause progressively stronger ratcheted contractions of the neuroblast apical cortex.
- Actin nucleation by bacterial virulence factors
How the bacterial virulence factors VopL/F from Vibrio catalyze actin nucleation is unclear. Using multicolor TIRF microscopy imaging, Burke et al. find that VopL and VopF stimulate actin assembly via identical pointed-end nucleation mechanisms.
- Hh signaling specifies precursors of GSC niches
The mechanisms of stem cell niche formation are largely unknown. Lai et al. show that proper formation of the Drosophila melanogaster adult ovarian germline stem cell niche requires a Hedgehog gradient, signaling through a Ci–Traffic Jam–E-cadherin regulatory axis, to direct segregation of intermingled cells by differential cell affinity.