Estrogen receptor mediates a distinct mitochondrial unfolded protein response

Luena Papa, Doris Germain

Research output: Contribution to journalArticlepeer-review

161 Scopus citations


Unfolded protein responses (UPRs) of the endoplasmic reticulum and mitochondrial matrix have been described. Here, we show that the accumulation of proteins in the inter-membrane space (IMS) of mitochondria in the breast cancer cell line MCF-7 activates a distinct UPR. Upon IMS stress, overproduction of reactive oxygen species (ROS) and phosphorylation of AKT triggers estrogen receptor (ER) activity, which further upregulates the transcription of the mitochondrial regulator NRF1 and the IMS protease OMI (officially known as HTRA2). Moreover, we demonstrate that the IMS stress-induced UPR culminates in increased proteasome activity. Given our previous report on a proteasome- and OMI-dependent checkpoint that limits the import of IMS proteins, the findings presented in this study suggest that this newly discovered UPR acts as a cytoprotective response to overcome IMS stress.

Original languageEnglish
Pages (from-to)1396-1402
Number of pages7
JournalJournal of Cell Science
Issue number9
StatePublished - 1 May 2011


  • Estrogen receptor
  • Mitochondria
  • Proteasome
  • Protein quality control
  • Unfolded protein response


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