Liver disease-associated keratin 8 and 18 mutations modulate keratin acetylation and methylation

FASEB J. 2019 Aug;33(8):9030-9043. doi: 10.1096/fj.201800263RR. Epub 2019 Jun 14.


Keratin 8 (K8) and keratin 18 (K18) are the intermediate filament proteins whose phosphorylation/transamidation associate with their aggregation in Mallory-Denk bodies found in patients with various liver diseases. However, the functions of other post-translational modifications in keratins related to liver diseases have not been fully elucidated. Here, using a site-specific mutation assay combined with nano-liquid chromatography-tandem mass spectrometry, we identified K8-Lys108 and K18-Lys187/426 as acetylation sites, and K8-Arg47 and K18-Arg55 as methylation sites. Keratin mutation (Arg-to-Lys/Ala) at the methylation sites, but not the acetylation sites, led to decreased stability of the keratin protein. We compared keratin acetylation/methylation in liver disease-associated keratin variants. The acetylation of K8 variants increased or decreased to various extents, whereas the methylation of K18-del65-72 and K18-I150V variants increased. Notably, the highly acetylated/methylated K18-I150V variant was less soluble and exhibited unusually prolonged protein stability, which suggests that additional acetylation of highly methylated keratins has a synergistic effect on prolonged stability. Therefore, the different levels of acetylation/methylation of the liver disease-associated variants regulate keratin protein stability. These findings extend our understanding of how disease-associated mutations in keratins modulate keratin acetylation and methylation, which may contribute to disease pathogenesis.-Jang, K.-H., Yoon, H.-N., Lee, J., Yi, H., Park, S.-Y., Lee, S.-Y., Lim, Y., Lee, H.-J., Cho, J.-W., Paik, Y.-K., Hancock, W. S., Ku, N.-O. Liver disease-associated keratin 8 and 18 mutations modulate keratin acetylation and methylation.

Keywords: MDB; intermediate filament; post-translational modification; protein stability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Binding Sites / genetics
  • Cell Line
  • Cricetinae
  • HT29 Cells
  • Humans
  • Keratin-18 / chemistry
  • Keratin-18 / genetics*
  • Keratin-18 / metabolism*
  • Keratin-8 / chemistry
  • Keratin-8 / genetics*
  • Keratin-8 / metabolism*
  • Liver Diseases / genetics*
  • Liver Diseases / metabolism*
  • Mallory Bodies / metabolism
  • Methylation
  • Mutant Proteins / chemistry
  • Mutant Proteins / genetics*
  • Mutant Proteins / metabolism*
  • Mutation, Missense
  • Protein Processing, Post-Translational
  • Protein Stability
  • Tandem Mass Spectrometry


  • KRT18 protein, human
  • KRT8 protein, human
  • Keratin-18
  • Keratin-8
  • Mutant Proteins