Issues

Linton M. Traub and Frances M. Brodsky discuss the life and achievements of Ernst Ungewickell, who passed away on August 19th.

Dey and Baum preview work from Velle and Fritz-Laylin, which shows that Naegleria expresses conserved actin nucleators and generates Arp2/3-dependent lamellar protrusions.

Teves previews work from the Blower laboratory describing the importance of RNA exclusion from chromosomes for cells to divide.

Ambrosini and Röper preview work from Shard et al., which reveals Neuralized coordinates epithelial-to-neural stem cell transition in the Drosophila optic lobe.

Gliech and Holland discuss the guiding design principles of biological clocks across a variety of model systems.

Killackey et al. review recent advances and major questions in the field of mitophagy, as well as implications for mitophagy in disease.

Tirrell et al. determine that subcomplexes of the cristae-organizing MICOS complex assemble independently of one another on the mitochondrial inner membrane in proximity to contact sites between mitochondria and the endoplasmic reticulum.

Naegleria diverged from the “yeast-to-human” lineage >1 billion years ago. Velle and Fritz-Laylin found that Naegleria, which lacks interphase microtubules, has a robust actin cytoskeletal repertoire and uses conserved, Arp2/3–derived actin networks to drive cell crawling and enhance phagocytosis. These findings support an evolutionarily ancient origin for these phenotypes.

Polycomb group proteins play important roles in developmental and cell proliferation processes. Baumann et al. demonstrate that the PRC1 protein CBX2 is critical for heterochromatin homeostasis, chromosome stability, and the prevention of premature cellular senescence.

Molinuevo et al. show a novel control of epidermoid differentiation by the DNA damage response signals and propose a model for automatic cleansing of stratified self-renewal epithelia facing genotoxic agents.

Sharp et al. investigate cell cycle control of chromatin-associated RNP complexes. They find that Aurora-B and SAF-A control the redistribution of RNAs away from chromosomes in mitosis. This early mitotic chromosomal remodeling process is required for the fidelity of chromosome segregation.

Brandt et al. establish mechanisms that target Polo-like kinase during meiotic prophase in C. elegans. CDK-1 phosphorylates a synaptonemal complex component, SYP-1, to generate docking sites for PLK-2, whose association is prevented until crossover formation to ensure homologue pairing, synapsis, and chromosome remodeling.

Huang et al. show that formation of 80S-like ribosomes during small subunit maturation is a quality control step that tests head assembly to ensure the fidelity of start-codon selection.

This study investigates the role of septins in the cytolytic activity of natural killer (NK) cells. The findings reveal regulation of exocytosis of lytic granules by septins through their interaction with proteins involved in the fusion of lytic granules with the plasma membrane.

The polyproline-rich domain of Tau, the core constituent of neurofibrillary tangles, can undergo liquid–liquid phase separation in living cells. Tau PRD condensation drives clustering of Tau on microtubules under the control of phosphorylation and can form a co-condensate with EB1, a regulator of plus-end microtubule dynamic instability.

Using in vitro reconstitution assays and in vivo cellular phenotypes, Stancheva and colleagues dissect the protein interaction network that drives COPII coat assembly during vesicle formation from the endoplasmic reticulum, revealing the importance of multivalent interactions that mutually reinforce each other.

Allen et al. identify a conserved role for dMtmr6/CG3530 and MTMR8 in regulating autophagic flux. Decreased dMtmr6 function results in autophagic vesicle accumulation, influences endolysosomal homeostasis, and is required for Drosophila development.

Pedersen et al. investigate steps of the clathrin-mediated endocytosis pathway that are subject to regulation. They report position-dependent differences in endocytic site maturation rates in polarized cells and suggest that cargo controls endocytic internalization through tuning site maturation rather than site initiation.

Using oncogene-expressing cells to interrogate p53 function under physiological oxygen conditions, Valente et al. show that p53 deficiency drives concurrent dysregulation of a range of cellular processes. These findings highlight the pleiotropic effects of p53 inactivation.

Shard et al. show that the emergence of neural stem cells from the Drosophila optic lobe neuroepithelium is an EMT-like process involving tissue-wide coordination. Neuralized acts downstream of NSC fate acquisition to downregulate the Crumbs complex to facilitate epithelium remodeling.

Yang et al. find that in a single-celled tube, intermediate filaments act as a scaffold at the central lumen, which recruits proteins to regulate the addition of other structural elements to maintain cell integrity. These findings present a general mechanism for regulation of lumen diameter in biological tubes.

Cell and tissue morphogenesis are fundamental during development. The authors previously characterized Slik kinase and its effector, moesin, as regulators of mitotic morphogenesis and epithelial integrity. Here, they identify dSTRIPAK as a new regulator of Slik localization to promote moesin activation and functions.

Baumert et al. identify a novel “phospho-switch” within the neuronal protein delta-catenin. This phospho-switch, located at delta-catenin’s C-terminus, is sensitive to upstream glutamate signaling and instructs dendrites to branch versus extend during development by determining delta-catenin’s neuronal binding partners and subsequent modulation of actin-associated proteins.

Secretion and deposition of non-collagen ECM components is an elusive topic. Albacete-Albacete et al. identify exosome biogenesis and exosomal cargo sorting as novel mechanisms by which the stromal remodeling regulator caveolin-1 modulates ECM deposition, through the control of multivesicular body cholesterol content and plasticity.