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Updated: Mar 22, 2026

Author Spotlight: Decoding Mitochondrial Aging
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Mitochondrial Precursor Overaccumulation Stress

Liam P Coyne1, Xin Jie Chen2

  • 1Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.

Annual Review of Biochemistry
|March 20, 2026
PubMed

Insights

Mitochondrial precursor overaccumulation stress (mPOS) arises from impaired protein import, causing toxic cytosolic protein buildup. This stress impacts cell signaling, survival, and disease, independent of energy production deficits.

Area of Science:

  • Cellular Biology
  • Mitochondrial Biology
  • Stress Response

Background:

  • Mitochondrial damage causes cellular stress beyond energy deficits.
  • Mitochondrial precursor overaccumulation stress (mPOS) is a newly identified stress.
  • mPOS results from impaired mitochondrial protein import, leading to toxic precursor accumulation in the cytosol.

Purpose of the Study:

  • To review the discovery and significance of mPOS.
  • To discuss mPOS's role in mitochondria-induced stress signaling pathways.
  • To explore mPOS's impact on cell demise, human disease, and survival.

Main Methods:

  • Literature review of mPOS discovery and research.
  • Analysis of mPOS's connection to cellular signaling pathways.
  • Examination of mPOS's role in cell death and disease pathogenesis.

Main Results:

  • mPOS is characterized by the cytosolic accumulation of unimported mitochondrial proteins.
  • mPOS imposes a significant proteostatic burden, analogous to ER stress.
  • mPOS influences major mitochondria-induced stress signaling pathways.

Conclusions:

  • mPOS affects cell fitness and survival independently of bioenergetic deficits.
  • mPOS may represent a pathogenic mechanism in mitochondriopathies and aging-related diseases.
  • Understanding mPOS offers new insights into mitochondrial stress and disease.
Keywords:
diseasemPOSmitochondriamitochondrial precursor overaccumulation stressprotein importproteostasisstress signaling

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