ER-mitochondria contacts respond to cellular stress. Chai et al. reveal that in response to hypoxia, USP19, an ER-resident deubiquitinase, accumulates at ER-mitochondria contact sites where USP19 deubiquitinates and stabilizes FUNDC1, thereby promoting Drp1 oligomerization and subsequent hypoxia-induced mitochondria division.

Yang et al. develop a proteomics-based approach to systematically isolate asymmetrically localized proteins in Dictyostelium, through which they identify an LRR domain–containing protein named Leep1. Their results reveal that the spatiotemporal coordination of PIP3 signaling, Leep1, and Scar/WAVE complex modulates protrusion morphogenesis at the leading edge of cells.

Deliz-Aguirre et al. examine the molecular dynamics of interleukin 1 receptor signaling. Receptor sensing of IL-1 triggers the oligomerization of MyD88 and formation of the Myddosome signaling complex. The formation of a MyD88 oligomer of a requisite size serves as a threshold to active downstream signaling.

Ali-Murthy et al. show that during Drosophila oogenesis, several nurse cell nuclei move into the oocyte through a channel that opens when nurse cells and oocyte transiently fuse, and that nuclear transfer/elimination is essential for oocyte maturation and embryonic viability.

The Golgi matrix protein giantin is essential for normal skeletal formation. Here, Stevenson et al. show that it also has a role in fracture repair and is required for intracellular processing of the N-terminal propeptide of type I procollagen.

Herrera et al. discover that Dbnl and β-catenin cooperate to promote pro-N-cadherin processing. This study shows that β-catenin and Dbnl interact with phosphorylated pro-N-cadherin in the Golgi apparatus, promoting propeptide excision and the final maturation of N-cadherin, which is critical for adherens junction (AJ) formation and for apico-basal polarity maintenance. AJs concentrate at the subapical region of neural stem cells and are critical to maintaining apico-basal polarity as these cells differentiate. Here, we show that Dbnl and β-catenin cooperate to promote pro-N-cadherin processing, facilitating AJ assembly during neural tube development.

VMP1 and TMEM41B, integral membrane proteins of the ER, regulate the formation of autophagosomes, lipid droplets, and lipoproteins. Here, Li, Wang, et al. show that they have phospholipid scramblase activity, which is essential to the normal distribution of cholesterol and phosphatidylserine in mammalian cells.