Journal Club – June 2019

Spindle-F-Actin, Molecular Gearshifts, and Cytoplasmic Softening

Must Read

Spindle-F-Actin Interactions in Mitotic Spindles in an Intact Vertebrate Epithelium

Kita et al. | Molecular Biology of the Cell A compelling subject for striking microscopy images, microtubules have long been considered the major mechanical component of the mitotic spindle. But a long-standing question has been whether a second cytoskeletal system lurks beneath the surface. In this study, the Bement lab develops improved methods for preserving F-actin in embryonic epithelia and successfully visualizes F-actin associated with the mitotic spindle. The authors demonstrate that, like spindle microtubules, multiple populations of spindle-F-actin exist and reorganize as a function of the cell cycle. By providing some of the first evidence that F-actin is a component of the mitotic spindle in animal cells, this study challenges the view that F-actin is restricted to the cell periphery during cell division.

Discussion Point – The authors note that a significant pool of cytoplasmic F-actin is present during interphase as well as mitosis, and argue that non-cortical actin has been historically overlooked because of its lability in fixed samples.


In Vitro BioID: Mapping the CENP-A Microenvironment with High Temporal and Spatial Resolution

Enhancements to a proximity-based labeling approach allow mapping of cell-cycle-dependent structural proteins.
Remnant et al.  |  Molecular Biology of the Cell

Reviews and Perspectives

Spindle Assembly and Chromosome Dynamics During Oocyte Meiosis

A specialized form of cell division in the female egg provides insights into macromolecular assemblies and human health.
Mullen, Davis-Roca, and Wignall  |  Current Opinion in Cell Biology

Tools and Resources

Allen Institute for Cell Science Integrated Mitotic Stem Cell

The Allen Institute For Cell Science presents the Integrated Mitotic Stem Cell, a holistic view of the dividing cell assembled from a vast database of microscopy images.

Journal Club Picks

  • Actin and myosin self-organize into active liquid droplets reminiscent of the mitotic spindle.
    Weirich et al. |  Gardel Lab |  Proceedings of the National Academy of Sciences
  • The microtubule seam is as strong as other regions of the lattice.
    Szatkowski et al. |  Dima Lab |  The Journal of Physical Chemistry
  • A dynein mutant uncouples ATPase activity and directed movement.
    Niekamp et al. |  Bhabha Lab |  The EMBO Journal
  • The kinesin-1 neck linker acts as a molecular gearshift, toggling between force and speed.
    Budaitis et al. |  Verhey Lab |  eLife
  • The biased sidestepping of kinesin-3 KIF1A causes microtubule rotation in gliding assays.
    Mitra et al. |  Casademunt Lab |  Biophysical Journal
  • Bacterial cells accumulate FtsZ to a fixed threshold to control cell-size homeostasis.
    Si et al. |  Jun Lab |  Current Biology
  • Microtubules can organize into spindle-like arrays in the absence of motor proteins.
    Edozie et al. |  Ross Lab |  Soft Matter
  • Actin filaments block the elongation of new microtubules at the centrosome.
    Inoue et al. |  Théry Lab |  The EMBO Journal
  • Actin and keratin disassembly near the spindle midzone causes local cytoplasmic softening.
    Field et al. |  Mitchison Lab |  Current Biology
  • The Ndc80 complex undergoes auto-inhibition by conformational folding.
    Scarborough et al. |  Davis and Asbury Labs |  eLife
  • Cleared Xenopus extracts are active in peroxisome protein transport.
    Romano et al. |  Rapoport Lab |  Journal of Cell Biology

Our opinions are our own and do not represent the views or endorsement of the authors cited.

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