Drosophila border cells are an established in vivo model for collective cell migration. Miao et al. show that a spliceosome C complex component, Cactin, is essential to coordinate apicobasal polarity among collectively migrating cells and that migrating cells are more sensitive to perturbed polarity than stationary epithelial cells.

UPR^mt increases mitochondrial quality control proteins and induces longevity. But how do the rescuing proteins enter mitochondria, as UPR^mt is initiated with dampened mitochondrial import? The study by Xin et al. shows that enhanced mitochondrial import mediates UPR^mt-induced lifespan extension upon UPR^mt activation.

Zhang et al. reconstitute branching microtubule nucleation using native and recombinant human augmin–γ-TuRC complex and highlight the importance of the adaptor protein NEDD1 and CDK1/PLK1-mediated phosphorylation in this process. This study also unravels a novel augmin’s oligomerization-dependent mechanism for γ-TuRC activation.

Unconventional protein secretion (UPS) mediates protein exocytosis without entering the ER-Golgi secretory route. Here, Wang et al. report SMGL-1 acts as a guanine nucleotide exchange factor for RAB-8 to facilitate apical UPS of integral proteins in Caenorhabditiselegans intestinal epithelia.

Most forms of cancer involve a step where cells move out of an epithelial layer, a step that requires the loss of the apical domain of epithelial cells. We show how this loss of polarity is regulated at multiple levels by key polarity proteins.

Farkas et al. identify monotopic hairpin proteins as novel clients of the guided entry of tail-anchored proteins (GET) pathway. They demonstrate that high efficiency GET pathway–mediated ER targeting of the budding yeast hairpin protein Erg1, a key enzyme of sterol synthesis, becomes essential under conditions requiring increased Erg1 biogenetic flux.

Ahmad and colleagues report that presynaptic accumulation of NRG3 involves multiple processes that include release of the EGF-containing domain from the TGN following BACE1 cleavage, transcytosis from somatodendritic to axonal plasma membranes, and selective retention at glutamatergic terminals through trans-synaptic interactions with postsynaptic ErbB4 receptors.