Lysosomotropic agents including azithromycin, chloroquine and hydroxychloroquine activate the integrated stress response

Cell Death Dis. 2021 Jan 6;12(1):6. doi: 10.1038/s41419-020-03324-w.


The integrated stress response manifests with the phosphorylation of eukaryotic initiation factor 2α (eIF2α) on serine residue 51 and plays a major role in the adaptation of cells to endoplasmic reticulum stress in the initiation of autophagy and in the ignition of immune responses. Here, we report that lysosomotropic agents, including azithromycin, chloroquine, and hydroxychloroquine, can trigger eIF2α phosphorylation in vitro (in cultured human cells) and, as validated for hydroxychloroquine, in vivo (in mice). Cells bearing a non-phosphorylatable eIF2α mutant (S51A) failed to accumulate autophagic puncta in response to azithromycin, chloroquine, and hydroxychloroquine. Conversely, two inhibitors of eIF2α dephosphorylation, nelfinavir and salubrinal, enhanced the induction of such autophagic puncta. Altogether, these results point to the unexpected capacity of azithromycin, chloroquine, and hydroxychloroquine to elicit the integrated stress response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use*
  • Azithromycin / pharmacology
  • Azithromycin / therapeutic use*
  • Chloroquine / pharmacology
  • Chloroquine / therapeutic use*
  • Humans
  • Hydroxychloroquine / pharmacology
  • Hydroxychloroquine / therapeutic use*
  • Mice


  • Anti-Bacterial Agents
  • Hydroxychloroquine
  • Azithromycin
  • Chloroquine