Issues

We are pleased to introduce the newest members of the JCB editorial board.

JCB asks early career researchers to share their experience interviewing for academic faculty positions and becoming independent PIs during the COVID-19 pandemic.

Gardner highlights work from Ayukawa et al. that reveals that microtubule oligomer curvature, rather than length, is the limiting factor that slows the microtubule nucleation rate.

Seaman previews work from the Jia laboratory describing how MAPK signaling regulates endosomal protein sorting during stress.

Haddix and Rasband discuss work from Wang et al. describing how neuromuscular synapse elimination influences myelination.

Romet-Lemonne and Jégou discuss recent evidence that actin filaments can both grow and shrink in elongation-promoting conditions.

Panicker et al. summarize the functions of monogenic Parkinson’s disease genes and the major cell biological pathways that contribute to neurodegeneration.

Assembly of the destruction complex is critical for Wnt/β-catenin signaling. Nong et al. find that Axin undergoes liquid–liquid phase separation, which is promoted by APC. Phase-separated Axin provides a scaffold for recruitment of GSK3β, CK1α, and β-catenin and facilitates GSK3β-mediated β-catenin phosphorylation and thus degradation.

Balmer et al. identify a new player in the complex network of epigenetic modifiers safeguarding stem and progenitor cell pools in stratified epithelia. SUV39H2, an enzyme introducing repressive methyl marks on chromatin, governs the master switch of stem and progenitor cells during epithelial fate conversion.

Restricting the localization of CENP-A to centromeres is essential to prevent chromosomal instability (CIN). CENP-A is overexpressed and mislocalized in several cancers. Shrestha et al. show that overexpression of CENP-A leads to its mislocalization, CIN, and aneuploidy with karyotypic heterogeneity.

Structured illumination microscopy, cryo-ET, and computational analyses reveal that nuclear pore complexes (NPCs) and specific lamins spatially distribute in a codependent manner. Knocking out certain lamin genes or knocking down particular nucleoporins perturbs how both lamins and NPCs distribute in the nuclear envelope.

This research identifies the interactors of TORC1 by genome-wide BiFC screens and reveals that a spatially distinct portion of TORC1 interacts with RNA-binding proteins. As a component of mRNP complexes, TORC1 phosphorylates Scd6 to negatively regulate Scd6 activity in translational repression and P-body accumulation.

Proteins within the core region of the centriole remain challenging to be resolved in vivo. Tian et al. present a spatiotemporal map of the centriole core and implications of how the proteins might interact to build the ninefold symmetrical centriole.

Ayukawa, Iwata, Imai, et al. visualize the early intermediates in the pathway of spontaneous nucleation of microtubules by using rapid flush negative stain electron microscopy. This study demonstrates that the formation of straight tubulin oligomers of critical size is essential for nucleation.

Kinesin-3 motors are fast and superprocessive, but their force generation properties remain unclear. The authors show that KIF1A detaches under low opposing forces but rapidly reattaches to continue motility. Rapid reattachment depends on the class-specific K-loop, whereas mutations linked to neurodevelopmental disorders impair force generation and motility.

How protein endocytic recycling changes in response to environmental cues is poorly understood. Mao et al. demonstrated that multiple stresses inhibited endocytic recycling via MAPK11/14-mediated phosphorylation of SNX27 at Ser51. Phosphorylation of SNX27 decreases its binding to cargo proteins and suppresses protein endocytic recycling.

Chen et al. have studied how Caenorhabditis elegans copes with an acute heat stress that alters its development and induces the fragmentation of mitochondria. A DRP-1–dependent autophagy process takes place as part of the worm’s adaptive mechanism in response to heat stress. DRP-1 participates in the coordination between mitochondrial fission and autophagosome biogenesis.

Dobramysl et al. find that protein complexes at filopodial tips are strongly heterogeneous. Using a combination of in vivo imaging in Drosophila, a cell-free system, and mathematical modeling, they propose that pairs of proteins form distinct subcomplexes that integrate diverse regulatory pathways to drive constrained filopodial dynamics.

Dendritic cell (DC) actin dynamics at the immunological synapse with T cells is partially regulated by the WAVE regulatory complex. Absence of DC WAVE leads to reduced actin dynamics, prolonged cell–cell contacts, and impaired T cell priming.

Fic et al. identify Drosophila RhoGAP19D as a novel epithelial polarity factor that excludes active Cdc42 from the lateral domain. Loss of RhoGAP19D causes apical domain expansion, lateral contractility, and invasion of adjacent tissues, a phenotype resembling that of precancerous breast lesions.

Li et al. identify SNT-1 and SNT-3 as the primary and secondary Ca²⁺ sensors that trigger Ca²⁺-dependent exocytosis of synaptic vesicles at the Caenorhabditis elegans neuromuscular junction. These two Ca²⁺ sensors display differential domain structure and axonal distribution, and mediate synaptic vesicle release with different synaptic properties.

Postnatal motor neurons undergo extensive competitive remodeling and synchronously myelinate. Wang et al. now reveal that axon remodeling and myelination intersect. While myelination does not predetermine competition outcome, completing remodeling allows myelination to accelerate. This involves cytoskeletal maturation, which enables increased delivery of promyelinating signals.

Junyent et al. describe how the cell communication through cytonemes that leads to synthetic embryogenesis is altered upon pluripotency state transition in stem cells. They show that in more developmentally advanced stem cells, Wnt-iGluR crosstalk in the cytonemes is impaired, resulting in reduced formation of synthetic embryo structures.

Ubiquitin conjugation to histone lysines regulates diverse processes such as gene silencing, transcriptional elongation, and DNA repair. Combining an avidity-based design strategy with molecular dynamics simulations, dos Santos Passos et al. develop genetically encoded sensors for H2AK13/15 or H2BK120 ubiquitinated nucleosomes and use them in live cells to monitor ubiquitin-dependent signaling.