Microtubules control nuclear shape and gene expression during early stages of hematopoietic differentiation.

Hematopoietic stem and progenitor cells (HSPC) can differentiate into all hematopoietic lineages to support hematopoiesis. Cells from the myeloid and lymphoid lineages fulfill distinct functions with specific shapes and intra-cellular architectures. The role of cytokines in the regulation of HSPC differentiation has been intensively studied but our understanding of the potential contribution of inner cell architecture is relatively poor.

Beyond Equilibrium Phase Diagrams: Enzymatic Activity Shakes Up Bacterial Condensates.

Phase separation is a thermodynamic process, but cells are inherently out of equilibrium. Guilhas et al. (2020) identify an active process through which an ATP-dependent motor controls the number and position of biomolecular condensates in bacteria.

Clusters of bacterial RNA polymerase are biomolecular condensates that assemble through liquid-liquid phase separation.

Once described as mere "bags of enzymes," bacterial cells are in fact highly organized, with many macromolecules exhibiting nonuniform localization patterns. Yet the physical and biochemical mechanisms that govern this spatial heterogeneity remain largely unknown. Here, we identify liquid-liquid phase separation (LLPS) as a mechanism for organizing clusters of RNA polymerase (RNAP) in Using fluorescence imaging, we show that RNAP quickly transitions from a dispersed to clustered localization pattern as cells enter log phase in nutrient-rich media.

Polarized cellular patterns of endocannabinoid production and detection shape cannabinoid signaling in neurons.

Neurons display important differences in plasma membrane composition between somatodendritic and axonal compartments, potentially leading to currently unexplored consequences in G-protein-coupled-receptor signaling. Here, by using highly-resolved biosensor imaging to measure local changes in basal levels of key signaling components, we explored features of type-1 cannabinoid receptor (CB1R) signaling in individual axons and dendrites of cultured rat hippocampal neurons. Activation of endogenous CB1Rs led to rapid, Gi/o-protein- and cAMP-mediated decrease of cyclic-AMP-dependent protein kinase (PKA) activity in the somatodendritic compartment.