Journal: Journal of Cell Biology

Abbreviation

J. Cell Biol.

Publisher

Rockefeller University Press

Journal Volumes

ISSN

0021-9525
1540-8140

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Filters

2022 - 20256
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Publications 1 - 6 of 6
  • uPA-mediated remodeling of CCL21 gradients regulates lymphatic migration of dendritic cells
    Item type: Journal Article
    Collado-Diaz, Victor; Christakopoulou, Maria-Nefeli; Schineis, Philipp; et al. (2025)
    Journal of Cell Biology
  • A nucleotide binding–independent role for γ-tubulin in microtubule capping and cell division
    Item type: Journal Article
    Berman, Adi Y.; Wieczorek, Michal; Aher, Amol; et al. (2023)
    Journal of Cell Biology
    The γ-tubulin ring complex (γ-TuRC) has essential roles in centrosomal and non-centrosomal microtubule organization during vertebrate mitosis. While there have been important advances in understanding γ-TuRC-dependent microtubule nucleation, γ-TuRC capping of microtubule minus-ends remains poorly characterized. Here, we utilized biochemical reconstitutions and cellular assays to characterize the human γ-TuRC’s capping activity. Single filament assays showed that the γ-TuRC remained associated with a nucleated microtubule for tens of minutes. In contrast, caps at dynamic microtubule minus-ends displayed lifetimes of ∼1 min. Reconstituted γ-TuRCs with nucleotide-binding deficient γ-tubulin (γ-tubulinΔGTP) formed ring-shaped complexes that did not nucleate microtubules but capped microtubule minus-ends with lifetimes similar to those measured for wild-type complexes. In dividing cells, microtubule regrowth assays revealed that while knockdown of γ-tubulin suppressed non-centrosomal microtubule formation, add-back of γ-tubulinΔGTP could substantially restore this process. Our results suggest that γ-TuRC capping is a nucleotide-binding-independent activity that plays a role in non-centrosomal microtubule organization during cell division.
  • Identification of coilin interactors reveals coordinated control of Cajal body number and structure
    Item type: Journal Article
    Arias Escayola, Dahyana; Zhang, Chuyue; Nischwitz, Emily; et al. (2025)
    Journal of Cell Biology
    The cell nucleus contains distinct biomolecular condensates that form at specific genetic loci, organize chromosomes in 3D space, and regulate RNA processing. Among these, Cajal bodies (CBs) require key "scaffolding" proteins for their assembly, which is not fully understood. Here, we employ proximity biotinylation, mass spectrometry, and functional screening to comprehensively identify and test the functions of CB components. We document 144 protein interactors of coilin, of which 70 were newly detected, and establish 25 players needed for CB assembly and/or maintenance. Surprisingly, the depletion of nine coilin interactors-mostly constituents of the 60S ribosome (RPLs)-increased CB number and caused subdomains defined by coilin and the survival motor neuron protein (SMN) to merge. These phenotypes were traceable to altered nuclear levels of dimethylarginine. Our data implicate RPL24 and other players in the regulation of CBs by modulating posttranslational modifications. Moreover, the prevalence of transcription factors among the identified components highlights roles for gene activity in CB assembly and nuclear positioning.
  • Clathrin coats partially preassemble and subsequently bend during endocytosis
    Item type: Journal Article
    Mund, Markus; Tschanz, Aline; Wu, Yu-Le; et al. (2023)
    Journal of Cell Biology
    Eukaryotic cells use clathrin-mediated endocytosis to take up a large range of extracellular cargo. During endocytosis, a clathrin coat forms on the plasma membrane, but it remains controversial when and how it is remodeled into a spherical vesicle. Here, we use 3D superresolution microscopy to determine the precise geometry of the clathrin coat at large numbers of endocytic sites. Through pseudo-temporal sorting, we determine the average trajectory of clathrin remodeling during endocytosis. We find that clathrin coats assemble first on flat membranes to 50% of the coat area before they become rapidly and continuously bent, and this mechanism is confirmed in three cell lines. We introduce the cooperative curvature model, which is based on positive feedback for curvature generation. It accurately describes the measured shapes and dynamics of the clathrin coat and could represent a general mechanism for clathrin coat remodeling on the plasma membrane.
  • Structure of the microtubule-anchoring factor NEDD1 bound to the γ-tubulin ring complex
    Item type: Journal Article
    Muñoz-Hernández, Hugo; Xu, Yixin; Pellicer Camardiel, Aitor; et al. (2025)
    Journal of Cell Biology
    The γ-tubulin ring complex (γ-TuRC) is an essential multiprotein assembly that provides a template for microtubule nucleation. The γ-TuRC is recruited to microtubule-organizing centers (MTOCs) by the evolutionarily conserved attachment factor NEDD1. However, the structural basis of the NEDD1-γ-TuRC interaction is not known. Here, we report cryo-EM structures of NEDD1 bound to the human γ-TuRC in the absence or presence of the activating factor CDK5RAP2. We found that the C-terminus of NEDD1 forms a tetrameric α-helical assembly that contacts the lumen of the γ-TuRC cone and orients its microtubule-binding domain away from the complex. The structure of the γ-TuRC simultaneously bound to NEDD1 and CDK5RAP2 reveals that both factors can associate with the "open" conformation of the complex. Our results show that NEDD1 does not induce substantial conformational changes in the γ-TuRC but suggest that anchoring of γ-TuRC-capped microtubules by NEDD1 would be structurally compatible with the significant conformational changes experienced by the γ-TuRC during microtubule nucleation.
  • Meiotic nuclear pore complex remodeling provides key insights into nuclear basket organization
    Item type: Journal Article
    King, Grant A.; Wettstein, Rahel; Varberg, Joseph M.; et al. (2022)
    Journal of Cell Biology
    Nuclear pore complexes (NPCs) are large proteinaceous assemblies that mediate nuclear compartmentalization. NPCs undergo large-scale structural rearrangements during mitosis in metazoans and some fungi. However, our understanding of NPC remodeling beyond mitosis remains limited. Using time-lapse fluorescence microscopy, we discovered that NPCs undergo two mechanistically separable remodeling events during budding yeast meiosis in which parts or all of the nuclear basket transiently dissociate from the NPC core during meiosis I and II, respectively. Meiosis I detachment, observed for Nup60 and Nup2, is driven by Polo kinase-mediated phosphorylation of Nup60 at its interface with the Y-complex. Subsequent reattachment of Nup60-Nup2 to the NPC core is facilitated by a lipid-binding amphipathic helix in Nup60. Preventing Nup60-Nup2 reattachment causes misorganization of the entire nuclear basket in gametes. Strikingly, meiotic nuclear basket remodeling also occurs in the distantly related fission yeast, Schizosaccharomyces pombe. Our study reveals a conserved and developmentally programmed aspect of NPC plasticity, providing key mechanistic insights into the nuclear basket organization.
Publications 1 - 6 of 6