Huang and Kanchanawong highlight a pair of studies from Fujiwara et al. that describe the development of an ultra high-speed single-molecule fluorescence imaging platform that helps elucidate the long-sought dynamic architecture of plasma membrane.
Oiling the wheels of nuclear division: SUMOylation regulates the expansion of the mitotic nuclear membrane
Symeon Siniossoglou discusses work from the Wozniak lab, which shows that transient SUMOylation of inner nuclear membrane proteins drives expansion of the nuclear membrane during mitosis.
Rapaport and Herrmann preview work from Pleiner et al., which examines the mechanism underlying the selectivity filter in the ER membrane protein complex (EMC) and maintains the integrity of the ER proteome.
Ivanovska and Tobin plus coworkers show that fat-filled lipid droplets have a high interfacial tension which helps to maintain the sphericity of small droplets—even when interacting with the cytoskeleton and nucleus that can be deformed and sometimes disrupted by small droplets.
Meng et al. report that upon plasma membrane damage in a cell, the Golgi apparatus accumulates at the wound site and facilitates membrane repair by converting PtdIns4P to PtdIns(4,5)P2 in C. elegans. This finding advances our understanding of cellular survival mechanisms under mechanical stress.
During mitosis, duplicated chromosomes are segregated to daughter cells. The cell detaches improperly attached chromosomes from their associated microtubules to prevent errors in chromosome segregation. In this work, it is found that the mechanical forces produced via the dynamic growth and shortening of microtubules act to efficiently facilitate these detachment events.
The mechanism of how mitotic kinetochores accomplish robust, long-distance coupling with spindle microtubule plus-ends during metaphase and anaphase is unknown. This work demonstrates that the replication licensing protein Cdt1 synergizes with kinetochore Ndc80 and the Ska1 complexes to form a tripartite Ndc80-Cdt1-Ska1 complex that processively tracks the plus-ends of dynamic microtubules.
Nuclear envelope (NE) budding is a nuclear export pathway for large macromolecular machineries. Davidson et al. show that the Centralspindlin proteins Pav and Tum work in two different nuclear WASH complexes to regulate the physical machineries of NE budding.
Saik et al. show that multiple yeast inner nuclear membrane (INM) proteins are SUMOylated during mitosis. These INM-specific SUMOylation events support mitotic nuclear membrane expansion by increasing INM phosphatidic acid levels, temporally coupling membrane expansion with the re-establishment of INM–chromatin interactions during mitosis.
Okafor et al. conducted single-cell chromatin accessibility analysis. They identified Betaglycan protein as a marker of self-renewing muscle satellite cells that can be purified and efficiently contribute to muscle regeneration after transplantation. Mechanistically, SMAD4 is genetically required for self-renewal in vivo by restricting differentiation.
Pleiner, Hazu, Pinton Tomaleri et al. identify a selectivity filter in the ER membrane protein complex (EMC) and show that the EMC protects the integrity of the ER proteome by limiting the misinsertion of mitochondrial tail-anchored proteins and enforcing the correct topology of multipass membrane proteins.
Fátima Martín-Sánchez et al. show that the structure of the inflammasome oligomer formed by the apoptosis-associated speck-like protein with a caspase recruitment domain (ASC) could change in conditions of low intracellular K+, allowing the CARD domain of ASC to be more accessible for the recruitment of pro-caspase-1 CARD domain.
Wang et al. demonstrate that ULK phosphorylates STX17 at residue Ser289, promoting its specific localization on autophagosomes. The interaction between ATG8 family proteins and STX17, mediated by FLNA, is facilitated by ULK phosphorylation of STX17 at Ser289, promoting recruitment to autophagosomes and enhancing autophagosome–lysosome fusion.
Hitomi et al. reveal that phosphatidylinositol 3-kinase complex I, essential for autophagosome biogenesis, is recruited to the autophagosome precursor via the interactions with the vacuolar membrane anchor Vac8, the PAS scaffold Atg1 complex, and the pre-autophagosomal vesicle component Atg9.
Membrane shapers from two distinct superfamilies cooperate in the development of neuronal morphology
Establishing proper dendritic arbors is indispensable for neuronal network formation and brain functions. Izadi et al. unveil physical interactions and cooperative functions of members of two fundamentally different superfamilies of membrane shapers and thereby reveal a previously unknown pivotal principle in neuronal shape development.
Hakanpää et al. show that reticular adhesions are assembled at flat clathrin lattices, a process inhibited by fibronectin and its receptor, integrin α5β1. This novel adhesion assembly mechanism is coupled to cell migration and reveals a unique crosstalk between cell-matrix adhesions.
The ultrafast camera with single fluorescent-molecule sensitivities developed by Fujiwara et al. has greatly improved the time resolution of single-molecule localization microscopy, revealing the focal adhesion’s dynamic nano-architecture and leading to the model of compartmentalized archipelago of focal-adhesion protein islands.
Illukkumbura et al. reveal that cluster-dependent tuning of membrane binding rather than size-dependent coupling to the actomyosin cortex enables differential transport of PAR proteins by cortical flows in the C. elegans zygote.
Minckley et al. identify a Zn2+-dependent mechanism that regulates microtubule-based processes, in which microtubule decoration by Zn2+ disturbs axonal transport via directly inhibiting movement of motor proteins and regulating microtubule binding of doublecortin (DCX), tau, and MAP2C, without disrupting other MAPs.
An ultrafast camera developed by Fujiwara et al. allows single fluorescent-molecule imaging every 33 µs with a localization precision of 34 nm (every 100 µs; 20 nm) and enables ultrafast PALM imaging of whole live cells.