Schormann et al. provide a reference library of confocal micrographs of key organelles in live epithelial cells as landmarks and a derived feature set that can be used to assign protein localization throughout the secretory pathway and to key organelles via a quantitative unbiased image-based classifier.
The authors show the dual regulation of phagosomal degradation and migration of Drosophila macrophages by Trpml, a lysosomal calcium channel. Trpml promotes cell migration by activating actomyosin contractility but supports phagosomal degradation through a myosin-independent mechanism.
The spindle assembly checkpoint requires recruitment of Mad1-C-Mad2 to unattached kinetochores but also Mad1 binding to Megator/Tpr at nuclear pore complexes during interphase. Cunha-Silva et al. provide evidence that this spatiotemporal redistribution is due to Mps1-mediated dissociation of Mad1 from Megator/Tpr during prophase, which is critical for Mad1-C-Mad2 accumulation at unattached kinetochores and for the accuracy of chromosome segregation in vivo.
Coat disassembly, driven by the Hsc70 “uncoating ATPase” and mediated by auxilin, occurs within seconds after vesicle release. Using single-molecule imaging, He et al. find that auxilins are absent from assembling pits. Therefore, Hsc70 is not responsible for the clathrin exchange during pit formation.
Nucleus centering in mouse oocytes depends on a gradient of actin-positive vesicle persistence. Modeling coupled to 3D simulations and experimental testing of predictions coming from the simulations demonstrate that this gradient nonspecifically centers large objects during prophase I and meiosis I in oocytes.