Cells recognize osmotic stress through liquid-liquid phase separation lubricated with poly(ADP-ribose)

Nat Commun. 2021 Mar 1;12(1):1353. doi: 10.1038/s41467-021-21614-5.


Cells are under threat of osmotic perturbation; cell volume maintenance is critical in cerebral edema, inflammation and aging, in which prominent changes in intracellular or extracellular osmolality emerge. After osmotic stress-enforced cell swelling or shrinkage, the cells regulate intracellular osmolality to recover their volume. However, the mechanisms recognizing osmotic stress remain obscured. We previously clarified that apoptosis signal-regulating kinase 3 (ASK3) bidirectionally responds to osmotic stress and regulates cell volume recovery. Here, we show that macromolecular crowding induces liquid-demixing condensates of ASK3 under hyperosmotic stress, which transduce osmosensing signal into ASK3 inactivation. A genome-wide small interfering RNA (siRNA) screen identifies an ASK3 inactivation regulator, nicotinamide phosphoribosyltransferase (NAMPT), related to poly(ADP-ribose) signaling. Furthermore, we clarify that poly(ADP-ribose) keeps ASK3 condensates in the liquid phase and enables ASK3 to become inactivated under hyperosmotic stress. Our findings demonstrate that cells rationally incorporate physicochemical phase separation into their osmosensing systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Cytokines / metabolism
  • HEK293 Cells
  • Humans
  • Lubrication*
  • MAP Kinase Kinase Kinases / chemistry
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism
  • MAP Kinase Kinase Kinases / ultrastructure
  • Models, Molecular
  • Mutation / genetics
  • NAD / metabolism
  • Nicotinamide Phosphoribosyltransferase / metabolism
  • Osmotic Pressure*
  • Phosphoprotein Phosphatases / metabolism
  • Poly Adenosine Diphosphate Ribose / metabolism*
  • Protein Domains


  • Cytokines
  • NAD
  • Poly Adenosine Diphosphate Ribose
  • Nicotinamide Phosphoribosyltransferase
  • nicotinamide phosphoribosyltransferase, human
  • MAP Kinase Kinase Kinases
  • MAP3K15 protein, human
  • Phosphoprotein Phosphatases
  • protein phosphatase 6