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Trans-endocytosis of ephrin receptor Eph into ephrin+ cells induces cell contact–mediated repulsion. Donor cells expressing EphB2-GFP/Flag (green; surface EphB2 in blue) contact responder cells expressing ephrinB (red). EphB2-ephrinB clusters form at contact sites and are internalized as vesicles (yellow). Nuclei appear in gray. EphB2 trans-endocytosis is regulated by a Rac/Tiam pathway that coordinates actin dynamics.Image © 2016 Gaitanos et al.
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People & Ideas
Lee et al. show that the ER in the C. elegans embryo is continuous, but its membrane is compartmentalized, as found in budding yeast and mouse NSCs. This compartmentalization plays a potential role in the polarity of the early embryo.
Sargent et al. identify the E3 ubiquitin ligase PEX2 as the causative agent of mammalian pexophagy. During amino acid starvation, PEX2 expression increases to ubiquitinate peroxisomal membrane proteins and signal peroxisome degradation by autophagy.
The GTPase Sec4p is a critical regulator of polarized membrane traffic. Lepore et al. show that the polo-like kinase Cdc5p phosphorylates Sec4p, which promotes coordinated membrane deposition during cytokinesis.
Munc18-1 heterozygous mutations are associated with developmental diseases, including early infantile epileptic encephalopathy (EIEE). Chai et al. report that Munc18-1 acts as a chaperone for α-synuclein and controls its aggregative propensity. Munc18-1 EIEE-associated mutations promote the aggregation of endogenous α-synuclein in neurons, leading to a neurodegenerative phenotype.
Invadopodia are membrane protrusions used by cancer cells to remodel and invade the extracellular matrix. Here, Rajadurai et al. show that the lipid phosphatase SHIP2 recruits the Ena/VASP-family actin regulatory protein Mena to stabilize invadopodia membrane protrusions and promote cell invasion.
Tiam–Rac signaling mediates trans-endocytosis of ephrin receptor EphB2 and is important for cell repulsion
Cell repulsion requires trans-endocytosis of ephrin receptors at cell–cell contact sites, but the mechanisms underlying this process are unclear. Here, Gaitanos et al. show that Tiam–Rac signaling mediates trans-endocytosis of EphB2 and is necessary for cell repulsion.
Organogenesis is regulated by specialized clusters of cells, the signaling centers. Their molecular regulation is well known, but the cellular behaviors involved remain ill defined. Here, Ahtiainen et al. use live imaging of embryonic mouse teeth to unveil cellular mechanisms driving epithelial invagination.
Visualization of single endogenous polysomes reveals the dynamics of translation in live human cells
Pichon et al. describe a method to visualize translation of single endogenous mRNPs in live cells and provide evidence for specialized translation factories, as well as measurements of translation elongation rate, ribosome loading, and movements of single polysomes.