People & Ideas
Guerrero and Gil discuss the recent discovery of the role of HMGB2 in establishing one of the hallmarks of senescence.
Martin discusses work by Xue and Sokac defining the motor requirements for ring closure during cellularization in Drosophila.
Moriwaki and Goshima identify the five molecular components that are necessary for recapitulation of all three phases of microtubule dynamics in vitro and show that Plk1 acts to shift microtubules to the mitotic mode.
Panas et al. review the mechanisms that control the dynamic formation and disassembly of RNA stress granules.
In senescence, specific genes encoding secreted factors are excluded from senescence-associated heterochromatin foci, but the mechanisms underlying this senescence-associated secretory phenotype (SASP) are unclear. Aird et al. show that the chromatin-bound protein HMGB2 orchestrates the SASP by preventing heterochromatin spreading to these specific loci.
The mechanisms mediating actomyosin ring contraction during Drosophila cellularization, a developmental division that resembles cytokinesis, are unclear. Xue and Sokac delineate the contribution of cytoskeletal motors and actin-binding proteins to actomyosin ring constriction as Drosophila embryos undergo cleavage.
Increased intracellular pH is necessary for adult epithelial and embryonic stem cell differentiation
Ulmschneider et al. demonstrate that intracellular pH increases during differentiation of Drosophila ovarian epithelial stem cells and mouse embryonic stem cells, that blocking this increase impairs differentiation, and that intracellular pH may regulate the strength of Hedgehog signaling in epithelial stem cells.
The mechanisms by which microtubule dynamics are regulated are not fully understood. In this study, the authors show that five proteins are sufficient to reproduce all three phases of microtubule plus end dynamics in vitro, and, furthermore, a mitotic kinase can modulate the dynamicity.
The temperature-sensitive TRP channel, TRPA1, is known to mediate Na+ and Ca2+ influx at the plasma membrane of sensory neurons. In this study, the authors show that TRPA1 is also present on the lysosomal membrane and mediates lysosome Ca2+ release in dorsal root ganglion neurons.
Murugesan et al. report that actomyosin arcs at the T cell synapse are formin-generated structures that directly propel T cell receptor cluster movement. The authors reveal the origin, organization, and functions of a major cytoskeletal network during synapse maturation.
This work demonstrates that Msi RNA-binding proteins are required for the exit of reserve intestinal stem cells from quiescence and further illustrates the importance of maintaining a quiescent pool of stem cells for regeneration of the intestinal epithelium after injury.
Semaphorins regulate guidance during cell migration. In addition to repelling endothelial cells, Hamm et al. identify a novel mechanism by which Semaphorin3d/Neuropilin1 regulates collective endothelial cell migration through activating a kinase cascade, which regulates Actin network organization and cell–cell contacts.