Sqstm1-GFP knock-in mice reveal dynamic actions of Sqstm1 during autophagy and under stress conditions in living cells

J Cell Sci. 2015 Dec 1;128(23):4453-61. doi: 10.1242/jcs.180174. Epub 2015 Oct 19.


Sqstm1 serves as a signaling hub and receptor for selective autophagy. Consequently, dysregulation of Sqstm1 causes imbalances in signaling pathways and disrupts proteostasis, thereby contributing to the development of human diseases. Environmental stresses influence the level of Sqstm1 by altering its expression and/or autophagic degradation, and also changes the localization of Sqstm1, making it difficult to elucidate the actions and roles of this protein. In this study, we developed knock-in mice expressing Sqstm1 fused to GFP (Sqstm1-GFP(KI/+)). Using these Sqstm1-GFP(KI/+) mice, we revealed for the first time the dynamics of endogenous Sqstm1 in living cells. Sqstm1-GFP was translocated to a restricted area of LC3-positive structures, which primarily correspond to the inside of autophagosomes, and then degraded. Moreover, exposure to arsenite induced expression of Sqstm1-GFP, followed by accumulation of the fusion protein in large aggregates that were degraded by autophagy. Furthermore, suppression of autophagy in Sqstm1-GFP(KI/+) mouse livers caused accumulation of Sqstm1-GFP and formation of GFP-positive aggregate structures, leading to severe hepatic failure. These results indicate that Sqstm1-GFP(KI/+) mice are a useful tool for analyzing Sqstm1 in living cells and intact animals.

Keywords: Autophagy; Knock-in mice; Nrf2; Selective autophagy; Sqstm1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / biosynthesis*
  • Adaptor Proteins, Signal Transducing / genetics
  • Animals
  • Autophagy*
  • Gene Expression Regulation*
  • Gene Knock-In Techniques
  • Green Fluorescent Proteins / biosynthesis
  • Green Fluorescent Proteins / genetics
  • Heat-Shock Proteins / biosynthesis*
  • Heat-Shock Proteins / genetics
  • Humans
  • Liver Failure / genetics
  • Liver Failure / metabolism
  • Mice
  • Mice, Transgenic
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Phagosomes / genetics
  • Phagosomes / metabolism*
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / genetics
  • Sequestosome-1 Protein
  • Stress, Physiological*


  • Adaptor Proteins, Signal Transducing
  • Heat-Shock Proteins
  • Map1lc3b protein, mouse
  • Microtubule-Associated Proteins
  • Recombinant Fusion Proteins
  • Sequestosome-1 Protein
  • Sqstm1 protein, mouse
  • Green Fluorescent Proteins