Susan A. Gerbi, Robert E. Palazzo, William C. Earnshaw, and William T. Schrader discuss the life and achievements of William R. Brinkley, who passed away on November 10, 2020.
People & Ideas
Verlhac previews work from Mori et al. that describes mechanisms by which the paternal chromosomes are segregated until the completion of egg meiosis.
Cozmescu and Gissen highlight work from Belicova et al., which shows that the hepatocyte apical membrane produces Rab35-dependent extensions important for bile canaliculi formation.
Lee and Ding highlight work from Hao et al. describing that membrane-bound stem cell factor synergizes with VCAM-1 to induce polarized protrusions that regulate adhesion in hematopoietic stem cells.
Knorr and colleagues discuss the interaction mechanism of phase-separated and membrane-bound compartments and propose that this interplay can be understood as intracellular wetting phenomenon.
Siu et al. review the cell biology of fertilization with a focus on the factors involved in gamete attachment and fusion.
Wu et al. find that in mouse oocytes, minor satellite transcripts play a protective role in preventing pericentromeric heterochromatin from breaking during meiosis I. Such breaks, when present, reduce rates of oocyte maturation through spindle assembly checkpoint activation and lead to chromosomal segregation defects.
Molenaar et al. show that seipin does not play a role in the biogenesis of lipid droplets composed mostly or only of the neutral lipid retinyl ester, even in cells that produce triacylglycerols.
This work identifies endoplasmic reticulum subdomains, where the sterol synthesis and export machineries are coupled to sustain endocytosis in yeast mother cells, but not in daughters, where endocytosis and plasma membrane loading with accessible sterols are linked to secretion.
Gilles et al. reveal that the phospholipase NOT-LIKE-DAD localizes on the endo-plasma membrane that surrounds the sperm cells in a pollen grain. This endo-PM has a PI(4,5)P2 lipid signature, and NOT-LIKE-DAD is addressed by lipid anchoring and electrostatic interactions. After pollen tube burst, the endo-PM locates within the embryo sac and helps to deliver the sperm cells.
Fast-growing microtubules are associated with large protective GTP-caps, raising the question of how cells achieve simultaneously fast and highly dynamic microtubule growth. Farmer et al. show that polymerase XMAP215 perturbs the growing microtubule end to promote microtubule catastrophe, despite simultaneously accelerating the microtubule growth rate.
Mori et al. report that zygotes have active mechanisms that regulate the localization of paternal chromosomes during fertilization. These mechanisms guarantee that paternal chromosomes are kept in the zygote, and their disruption causes the elimination of paternal chromosomes into a polar body.
In this study, Gao et al. demonstrate that the global loss of TDP-43 liquid–liquid phase separation perturbs brain function by modulating interactions of TDP-43 with PABPC4, RPS6, RPL7, and other translational factors to orchestrate protein synthesis.
Basu et al. elucidate a mechanism for anchoring mitochondria to the actin cytoskeleton. The actin-associated protein FHL2 provides the necessary and sufficient anchor. They demonstrate that FHL2 is recruited to mitochondria by O-GlcNAcylated TRAK in response to glucose sensing. Anchored mitochondria are remobilized upon F-actin disruption or FHL2 knockdown.
COPI vesicles recycle Golgi resident proteins within the Golgi stack. Welch et al. combine two orthogonal proteomic analyses to identify clients for the COPI adaptors GOLPH3 and GOLPH3L, and show that these adaptors interact with the cytoplasmic tails of enzymes from diverse glycosylation pathways by binding membrane-proximal positively charged residues.
Larocque et al. describe how tumor protein D52-like proteins associate with intracellular nanovesicles. These small transport vesicles are shown to be involved in recycling α5β1 integrins during cell migration and invasion.
Belicova et al. report previously unrecognized apical membrane extensions, forming a pattern reminiscent of the bulkheads of boats, that determine the anisotropic expansion of hepatocyte lumina. Loss of the bulkheads caused by Rab35 silencing leads to re-engineering of epithelial polarity and liver tissue architecture.
Frazer et al. use 4D imaging to reveal that while the intracellular pathways orchestrating killing within CTL are conserved, the rate of initiation along these pathways varies with TCR signal strength.
Membrane contact sites (MCSs) between the ER and other organelles, such as lipid droplets and peroxisomes, are essential for lipid homeostasis. This study shows that members of the Pex30 family of ER proteins function as organelle-specific adaptors for Pex30, enabling it to function at multiple MCSs.
Isensee et al. describe a peripheral mechanism by which excitation of nociceptive sensory neurons leads to pain hypersensitivity. Depolarization of nociceptors results in cAMP-independent activation of type II protein kinase A (PKA-II) by calcium influx through CaV1.2 channels, which in turn modulates calcium channel activity.
This work dissects the role of different KIF1A tail domains in motor activity and cargo binding. Based on the results, the authors propose a mechanism for the regulation of KIF1A cargo transport in hippocampal neurons.
Hematopoietic stem cells form a polarized morphology with enhanced adhesion and improved nuclear FOXO3a on membrane-bound SCF and VCAM-1 on a lipid bilayer. The work reveals a unique role of the niche membrane-bound factors in stem cell anchorage and maintenance.
Muriel et al. present a large correlative light and electron microscopy dataset of 3D tomograms of the fission yeast cell–cell fusion site. The work reveals that these isogametes present morphological asymmetries in plasma membrane tension and curvature.