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A ULK1-MTFR1L feedback loop links mitochondrial fission, mitophagy and apoptosis

Riccardo Babic1,2, Leon Lucya1, Christoph Reiter1

  • 1Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.

Journal of Cell Science
|April 13, 2026
PubMed

Insights

Researchers discovered MTFR1L, a protein crucial for mitophagy, linking mitochondrial fission to autophagy initiation. This finding is vital for understanding cell survival and mitochondrial quality control.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitophagy preserves mitochondrial quality by degrading damaged mitochondria.
  • The coordination between mitochondrial fission and autophagy initiation is not well understood.

Purpose of the Study:

  • To identify key components linking mitochondrial fission to mitophagy initiation.
  • To elucidate the role of MTFR1L in the mitophagy pathway.

Main Methods:

  • Utilized a synthetic FKBP-FRB system to tether ULK1 kinase to mitochondria.
  • Investigated MTFR1L enrichment at ULK1 foci and its impact on mitochondrial morphology.
  • Assessed the effects of MTFR1L depletion on cellular respiration, apoptosis, and mitophagy flux.

Main Results:

  • Identified MTFR1L as a key component of mitophagy initiation hubs.
  • Demonstrated that MTFR1L enrichment promotes mitochondrial fragmentation.
  • Showed MTFR1L phosphorylation by ULK1 creates a feedback loop, stabilizing ATG13.

Conclusions:

  • MTFR1L acts as a critical link between mitochondrial fission and the autophagy machinery.
  • MTFR1L coordinates mitophagy initiation, impacting cellular respiration, apoptosis, and cell survival.
Keywords:
ATG13AutophagyMTFR1LMitophagyULK1

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