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Biomolecular condensates are non-membrane-encapsulated compartments that control various biological processes. Recent studies have revealed that condensates change in response to stimuli and over time. This Review discusses the heterogeneity and composition changes of nuclear and cytoplasmic condensates, their regulation and how the changes affect cellular biochemical reactions.

Different environmental stressors induce different subtypes of stress granules (SGs), and each of them presumably have distinct functions. Here the authors provide a framework for understanding the compositional and functional heterogeneity of SGs, and see that TRIM25 mainly associates with anti-viral SGs.

Here, the authors unveil the evolutionary conservation of lysine-rich IDRs of snoRNPs that mediate both efficient rRNA modification during active ribosome production and nucleolar compaction when ribosome synthesis declines and snoRNPs accumulate in latent state.

The cell interior is organized by diverse membrane-less condensates. Here, the authors reveal that the densities of certain condensates are surprisingly low, similar to the surrounding protoplasm and driven by cellular RNA as well as the crowded milieu.

ZO-1, a cell junction protein, is essential for angiogenesis. Here the authors identify in endothelial cells unexpected associations of ZO-1 with stress granule proteins, such as YB-1, that are crucial for cytoprotection, implicating the ZO-1-YB-1 interaction in angiogenesis.

Stress granules are non-membranous organelles connected to stress responses and age-related disease. Here, the authors identify a conserved yeast protein, Lsm7, that facilitates stress granule formation through dynamic liquid-liquid phase separation condensates upon 2-deoxy-D-glucose-induced stress.

Cells must respond to environmental changes. In three fungal species adapted to different temperatures, cellular responses are conserved yet tuned to each organism’s thermal niche, including the formation of adaptive biomolecular condensates.

The factors regulating stress granule dissolution are not fully understood. Here, the authors identify Sky1 as a stress granule component in yeast, and show that Sky1 kinase activity is required for timely stress granule disassembly during stress recovery.

Low complexity (LC) domains can drive the formation of both amyloid fibrils and protein droplets. Here, the authors identify reversible amyloid cores from the LC of hnRNPA1, based on which they elucidate the structural basis of reversible fibrillation and its interplay with hnRNPA1 droplet formation.

Cereghetti et al. report that the glycolytic metabolite fructose-1,6-bisphosphate initiates the disassembly of amyloids formed by the yeast pyruvate kinase Cdc19 to resume ATP production during stress recovery.

Stress granules that form in response to stress contain translationally stalled mRNPs and play important roles in cellular homeostasis. Here the authors implicate SRSF3 neddylation as an important factor in the formation of stress granules in response to arsenite exposure.

Rbfox1, a pro-survival RNA-binding protein, is expressed in a complex manner and mediates diverse developmental processes. Here, the authors observe alternative splicing of Rbfox1 and stress-dependent regulation by miR-980 in Drosophila ovaries and Rbfox1 localisation in ribonucleoprotein granules in human cells.

Gaglia et al. show, using single-cell imaging and analysis in human tumours, that phase transition of heat-shock factor 1 (HSF1) to form intranuclear stress bodies mediates cell-fate decisions underlying cell survival or death.

By using multicolour single-molecule live imaging, Moon et al. show that the dynamics of the interaction between mRNAs and ribonucleoprotein granules are affected by translational status, mRNA length and granule size.

Membraneless organelles (MLOs) contribute to intracellular compartmentalization and to various cellular processes. This Review provides a guide to MLOs involved in gene regulation in eukaryotes, discussing their assembly, structure, roles in transcription, RNA processing and translation — particularly in stress conditions — and their disease relevance.

Recent studies have highlighted the contribution of RNA to cellular liquid–liquid phase separation and condensate formation. RNA features modulate the composition and biophysical properties of RNA–protein condensates, which have various cellular functions, including RNA transport and localization, supporting catalytic processes and responding to stress.

RNA-binding proteins regulate the use of mRNA during periods of stress, in part through the formation of transient membraneless organelles known as stress granules. In this Review, Wolozin and Ivanov examine the biology of such granules in neurons and their potential roles in a number of neurodegenerative diseases.

In addition to membrane-bound organelles, eukaryotic cells feature various membraneless compartments, including the centrosome, the nucleolus and various granules. Many of these compartments form through liquid–liquid phase separation, and the principles, mechanisms and regulation of their assembly as well as their cellular functions are now beginning to emerge.

Alborz Mazloomian et al. use small molecule inhibitors to disrupt EIF4A3’s ATPase and helicase function which affects alternative splicing and nonsense mediated decay of transcripts. They define a genome-wide pattern of motifs of RNA-binding proteins associated with EIF4A3 and find that stress granules are downregulated upon EIF4A3 inhibition.