Intracellular MLCK1 diversion reverses barrier loss to restore mucosal homeostasis

Nat Med. 2019 Apr;25(4):690-700. doi: 10.1038/s41591-019-0393-7. Epub 2019 Apr 1.


Epithelial barrier loss is a driver of intestinal and systemic diseases. Myosin light chain kinase (MLCK) is a key effector of barrier dysfunction and a potential therapeutic target, but enzymatic inhibition has unacceptable toxicity. Here, we show that a unique domain within the MLCK splice variant MLCK1 directs perijunctional actomyosin ring (PAMR) recruitment. Using the domain structure and multiple screens, we identify a domain-binding small molecule (divertin) that blocks MLCK1 recruitment without inhibiting enzymatic function. Divertin blocks acute, tumor necrosis factor (TNF)-induced MLCK1 recruitment as well as downstream myosin light chain (MLC) phosphorylation, barrier loss, and diarrhea in vitro and in vivo. Divertin corrects barrier dysfunction and prevents disease development and progression in experimental inflammatory bowel disease. Beyond applications of divertin in gastrointestinal disease, this general approach to enzymatic inhibition by preventing access to specific subcellular sites provides a new paradigm for safely and precisely targeting individual properties of enzymes with multiple functions.

Publication types

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

MeSH terms

  • Actomyosin / metabolism
  • Animals
  • Caco-2 Cells
  • Chronic Disease
  • Homeostasis* / drug effects
  • Humans
  • Inflammation / pathology
  • Inflammatory Bowel Diseases / pathology
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / metabolism*
  • Intracellular Space / enzymology*
  • Jejunum / drug effects
  • Jejunum / metabolism
  • Jejunum / pathology
  • Mice
  • Myosin Light Chains / metabolism
  • Myosin-Light-Chain Kinase / chemistry
  • Myosin-Light-Chain Kinase / metabolism*
  • Phosphorylation / drug effects
  • Protein Domains
  • Small Molecule Libraries / pharmacology
  • Tight Junctions / drug effects
  • Tight Junctions / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology


  • Myosin Light Chains
  • Small Molecule Libraries
  • Tumor Necrosis Factor-alpha
  • Actomyosin
  • Myosin-Light-Chain Kinase