March 2016 | Volume 212, No. 7
In This Issue
People & Ideas
- Laser microsurgery reveals conserved viscoelastic behavior of the kinetochore
This study establishes merotelic kinetochores as a new experimental model for studying the mechanical response of the kinetochore. Laser microsurgery and live-cell imaging in yeast and mammalian cells show a conserved viscoelastic response of the kinetochore.
- Shape–motion relationships of centering microtubule asters
To faithfully target the center of large eggs, microtubule asters translate their shape into directed motion through length-dependent microtubule forces mediated by dynein in the cytoplasm. Their speed is independent of aster shape but determined by their growth rate.
- The proteasome controls presynaptic differentiation through modulation of an on-site pool of polyubiquitinated conjugates
The intra-axonal events governing formation of presynaptic terminals are still poorly understood. Pinto et al. reveal a mechanism by which a localized decrease in proteasome degradation and resultant accumulation of polyubiquitinated proteins at nascent sites signal assembly of presynaptic terminals.
- Ca2+/H+ exchange by acidic organelles regulates cell migration in vivo
A vertebrate Ca2+/H+ exchanger (CAX), which is part of a widespread conserved family in animals, localizes to acidic organelles, tempers evoked Ca2+ signals, and regulates cell-matrix adhesion during neural crest cell migration.
- Distinct mechanisms eliminate mother and daughter centrioles in meiosis of starfish oocytes
Centriole elimination is essential for sexual reproduction. Borrego-Pinto et al. show that in starfish oocytes elimination proceeds by extrusion of mother centrioles to polar bodies, whereas the single remaining daughter centriole is eliminated in the cytoplasm, preparing the egg for fertilization.
- MLL5 maintains spindle bipolarity by preventing aberrant cytosolic aggregation of PLK1
Zhao et al. show that MLL5 and PLK interact in the cytosol and propose a model wherein MLL5 maintains spindle bipolarity by preventing cytosolic PLK1 aggregation during mitosis.
- G3BP–Caprin1–USP10 complexes mediate stress granule condensation and associate with 40S subunits
Stress granule condensation (SGC) of translationally arrested mRNAs requires G3BP, and G3BP-mediated SGC is inhibited by serine 149 phosphorylation, regulated by mutually exclusive binding of Caprin1 and USP10, and requires its RGG region for SGC and for interactions with 40S ribosomal subunits.
- Smoothened determines β-arrestin–mediated removal of the G protein–coupled receptor Gpr161 from the primary cilium
Pal et al. describe a two-step process determining removal of the cilia-localized GPCR, Gpr161, upon sonic hedgehog signaling. First, β-arrestins are recruited by the signaling-competent receptor in a smoothened-dependent manner. Second, clathrin-mediated endocytosis outside of the ciliary compartment coordinates removal.