Small-molecule modulators of INAVA cytosolic condensate and cell-cell junction assemblies

J Cell Biol. 2021 Sep 6;220(9):e202007177. doi: 10.1083/jcb.202007177. Epub 2021 Jul 12.

Abstract

Epithelial cells lining mucosal surfaces distinctively express the inflammatory bowel disease risk gene INAVA. We previously found that INAVA has dual and competing functions: one at lateral membranes where it affects mucosal barrier function and the other in the cytosol where INAVA enhances IL-1β signal transduction and protein ubiquitination and forms puncta. We now find that IL-1β-induced INAVA puncta are biomolecular condensates that rapidly assemble and physiologically resolve. The condensates contain ubiquitin and the E3 ligase βTrCP2, and their formation correlates with amplified ubiquitination, suggesting function in regulation of cellular proteostasis. Accordingly, a small-molecule screen identified ROS inducers, proteasome inhibitors, and inhibitors of the protein folding chaperone HSP90 as potent agonists for INAVA condensate formation. Notably, inhibitors of the p38α and mTOR pathways enhanced resolution of the condensates, and inhibitors of the Rho-ROCK pathway induced INAVA's competing function by recruiting INAVA to newly assembled intercellular junctions in cells where none existed before.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Caco-2 Cells
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cell Line, Tumor
  • GTPase-Activating Proteins / genetics*
  • GTPase-Activating Proteins / metabolism
  • Gene Expression Regulation / drug effects*
  • HEK293 Cells
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism
  • HeLa Cells
  • Humans
  • Intercellular Junctions / drug effects*
  • Intercellular Junctions / metabolism
  • Intercellular Junctions / ultrastructure
  • Interleukin-1beta / genetics
  • Interleukin-1beta / metabolism
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Mitogen-Activated Protein Kinase 14 / genetics
  • Mitogen-Activated Protein Kinase 14 / metabolism
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Nod2 Signaling Adaptor Protein / genetics
  • Nod2 Signaling Adaptor Protein / metabolism
  • Proteostasis / drug effects
  • Proteostasis / genetics
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / classification
  • Small Molecule Libraries / pharmacology*
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism
  • beta-Transducin Repeat-Containing Proteins / genetics*
  • beta-Transducin Repeat-Containing Proteins / metabolism

Substances

  • BTRC protein, human
  • Carrier Proteins
  • GTPase-Activating Proteins
  • HSP90 Heat-Shock Proteins
  • IL1B protein, human
  • INAVA protein, human
  • Interleukin-1beta
  • Intracellular Signaling Peptides and Proteins
  • NF-kappa B
  • NOD2 protein, human
  • Nod2 Signaling Adaptor Protein
  • Recombinant Fusion Proteins
  • Small Molecule Libraries
  • Tifab protein, human
  • beta-Transducin Repeat-Containing Proteins
  • cytohesin-2
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinase 14