Hepatocyte Stress Increases Expression of Yes-Associated Protein and Transcriptional Coactivator With PDZ-Binding Motif in Hepatocytes to Promote Parenchymal Inflammation and Fibrosis

Hepatology. 2020 May;71(5):1813-1830. doi: 10.1002/hep.30928. Epub 2020 Jan 3.


Background and aims: Activated hepatocytes are hypothesized to be a major source of signals that drive cirrhosis, but the biochemical pathways that convert hepatocytes into such a state are unclear. We examined the role of the Hippo pathway transcriptional coactivators Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) in hepatocytes to facilitate cell-cell interactions that stimulate liver inflammation and fibrosis.

Approach and results: Using a variety of genetic, metabolic, and liver injury models in mice, we manipulated Hippo signaling in hepatocytes and examined its effects in nonparenchymal cells to promote liver inflammation and fibrosis. YAP-expressing hepatocytes rapidly and potently activate the expression of proteins that promote fibrosis (collagen type I alpha 1 chain, tissue inhibitor of metalloproteinase 1, platelet-derived growth factor c, transforming growth factor β2) and inflammation (tumor necrosis factor, interleukin 1β). They stimulate expansion of myofibroblasts and immune cells, followed by aggressive liver fibrosis. In contrast, hepatocyte-specific YAP and YAP/TAZ knockouts exhibit limited myofibroblast expansion, less inflammation, and decreased fibrosis after CCl4 injury despite a similar degree of necrosis as controls. We identified cellular communication network factor 1 (CYR61) as a chemokine that is up-regulated by hepatocytes during liver injury but is expressed at significantly lower levels in mice with hepatocyte-specific deletion of YAP or TAZ. Gain-of-function and loss-of-function experiments with CYR61 in vivo point to it being a key chemokine controlling liver fibrosis and inflammation in the context of YAP/TAZ. There is a direct correlation between levels of YAP/TAZ and CYR61 in liver tissues of patients with high-grade nonalcoholic steatohepatitis.

Conclusions: Liver injury in mice and humans increases levels of YAP/TAZ/CYR61 in hepatocytes, thus attracting macrophages to the liver to promote inflammation and fibrosis.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Collagen Type I, alpha 1 Chain
  • Cysteine-Rich Protein 61 / genetics
  • Cysteine-Rich Protein 61 / metabolism
  • Disease Models, Animal
  • Gain of Function Mutation
  • Hepatocytes / metabolism*
  • Humans
  • Liver Cirrhosis / genetics
  • Liver Cirrhosis / metabolism*
  • Loss of Function Mutation
  • Mice
  • Non-alcoholic Fatty Liver Disease / genetics
  • Non-alcoholic Fatty Liver Disease / metabolism*
  • Stress, Physiological*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcriptional Coactivator with PDZ-Binding Motif Proteins
  • YAP-Signaling Proteins


  • Adaptor Proteins, Signal Transducing
  • COL1A1 protein, human
  • Cell Cycle Proteins
  • Collagen Type I, alpha 1 Chain
  • Cysteine-Rich Protein 61
  • Trans-Activators
  • Transcription Factors
  • Transcriptional Coactivator with PDZ-Binding Motif Proteins
  • WWTR1 protein, human
  • Wwtr1 protein, mouse
  • YAP-Signaling Proteins
  • YY1AP1 protein, human
  • Yap1 protein, mouse